Water heater

Abstract

To suppress increase in exhaust resistance of a water heater including a secondary heat exchanger discharging a combustion exhaust gas introduced from the rear side.SOLUTION: A water heater includes a primary heat exchanger and a secondary heat exchanger 20, and the secondary heat exchanger 20 includes a plurality of heat transfer pipes 21 and a casing 22 having the pipes arranged therein. The plurality of heat transfer pipes 21 includes a plurality of straight pipe parts 21A and U-shaped pipe parts for coupling ends of the pipe parts to each other. The straight pipe parts 21A are aligned to separate from each other in a vertical direction and a forward / backward direction. The casing 22 has a rear part with a gas inlet 28 and an upper part with a gas outlet 41, and includes a partition part 25 that partitions an internal space S1 of the casing 22 into an arrangement region S2 where the heat transfer pipes 21 are arranged and an upper side region S3 disposed on an upper side of the arrangement region and communicated with the gas outlet 41. An opening 46 disposed on a front side of the plurality of heat transfer pipes 21 and connecting the arrangement region S2 and the upper side region S3 is formed. The partition part 25 includes a plurality of through holes 43A each penetrating through the partition part 25 vertically and communicating the arrangement region S2 and the upper side region S3.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to a water heater.

Background Art

[0002] Conventionally, as a water heater that discharges combustion exhaust gas upward after heat exchange in a secondary heat exchanger, a water heating device described in Japanese Patent Application Laid-Open No. 2018-31496 (Patent Document 1 below) is known. The secondary heat exchanger described in Patent Document 1 includes a plurality of heat transfer tubes and a case in which the plurality of heat transfer tubes are disposed inside. An air supply port is provided in the rear wall portion of the case, and the combustion exhaust gas discharged from the primary heat exchanger is introduced into the case from the air supply port through an auxiliary can body. An inclined wall portion that slopes downward toward the front is provided in the upper wall portion of the case, and an opening portion is provided in a region between the front portion of the upper wall portion and the front end portion of the inclined wall portion. A flat box-shaped exhaust top that covers the inclined wall portion and the opening portion from above is fixed to the upper wall portion of the secondary heat exchanger, and an exhaust port that protrudes upward is provided in the exhaust top. The combustion exhaust gas introduced into the case from the air supply port flows forward in the region below the inclined wall portion, and after the heat quantity of the combustion exhaust gas is recovered by the heat transfer tubes, it rises along the front wall portion of the case and flows into the space between the inclined wall portion of the case and the exhaust top through the opening portion. Thereafter, the combustion exhaust gas flows backward along the inclined wall portion and is discharged to the outside through the exhaust port.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described secondary heat exchanger, compared with the secondary heat exchanger provided with an exhaust port at the front, since the flow path of the combustion exhaust gas becomes longer, there is a risk that the exhaust resistance increases and adversely affects the combustion performance of the water heater.

[0005] The present disclosure has been completed based on the above circumstances, and an object thereof is to suppress an increase in exhaust resistance of a water heater including a secondary heat exchanger that exhausts combustion exhaust gas introduced from the rear upward.

Means for Solving the Problems

[0006] The water heater of the present disclosure includes a primary heat exchanger for recovering sensible heat, and a secondary heat exchanger disposed above the primary heat exchanger. The secondary heat exchanger includes a plurality of heat transfer tubes and a housing in which the plurality of heat transfer tubes are disposed inside. Each of the plurality of heat transfer tubes includes a plurality of straight tube portions extending in the left-right direction and a plurality of U-shaped tube portions connecting ends of two adjacent straight tube portions. In a state where the plurality of heat transfer tubes are disposed inside the housing, the plurality of straight tube portions are arranged at intervals in the vertical direction and the front-rear direction. The housing has a gas inlet at the rear and a gas outlet at the upper part. The housing includes a partition portion that partitions an internal space of the housing into a disposition region in which the plurality of heat transfer tubes are disposed and an upper region disposed above the disposition region and communicating with the gas outlet. An opening is formed in the housing in front of the plurality of heat transfer tubes and connecting the disposition region and the upper region. The water heater guides the combustion exhaust gas introduced into the disposition region through the gas inlet forward and then guides it into the upper region through the opening and discharges it to the outside through the gas outlet, and the partition portion has a plurality of through holes penetrating the partition portion in the vertical direction and communicating the disposition region and the upper region.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to suppress an increase in exhaust resistance of a water heater including a secondary heat exchanger that exhausts combustion exhaust gas introduced from the rear upward.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be listed and exemplified. (1) The water heater of the present disclosure includes a primary heat exchanger for recovering sensible heat, and a secondary heat exchanger disposed above the primary heat exchanger. The secondary heat exchanger includes a plurality of heat transfer tubes and a housing in which the plurality of heat transfer tubes are disposed inside. Each of the plurality of heat transfer tubes includes a plurality of straight tube portions extending in the left-right direction, and a plurality of U-shaped tube portions connecting the ends of two adjacent straight tube portions. In a state where the plurality of heat transfer tubes are disposed inside the housing, the plurality of straight tube portions are arranged at intervals in the vertical direction and the front-rear direction. The housing has a gas inlet at the rear and a gas outlet at the upper part. The housing includes a partition portion that partitions the internal space of the housing into a disposition region where the plurality of heat transfer tubes are disposed and an upper region disposed above the disposition region and communicating with the gas outlet. An opening is formed in the housing in front of the plurality of heat transfer tubes to connect the disposition region and the upper region. The combustion exhaust gas introduced into the disposition region through the gas inlet is guided forward and then guided into the upper region through the opening and discharged to the outside through the gas outlet. The water heater is characterized in that the partition portion has a plurality of through holes penetrating the partition portion in the vertical direction and communicating the disposition region and the upper region.

[0010] According to such a configuration, by providing through holes in the partition portion, a part of the combustion exhaust gas flowing through the disposition region can be guided to the upper region, so that an excessive increase in exhaust resistance can be suppressed and the combustion performance of the water heater can be ensured.

[0011] (2) It is preferable that the gas outlet is located near the center in the left-right direction of the housing, and the through holes are disposed near the center in the left-right direction of the partition portion.

[0012] With such a configuration, since the combustion exhaust gas flowing through both left and right ends in the lateral direction of the installation region can be deflected toward the central portion in the lateral direction, the combustion exhaust gas easily flows near the straight pipe portion that is arranged closer to the central portion in the lateral direction of the installation region and has better heat transfer efficiency than the U-shaped pipe portion. Further, since the flow of the combustion exhaust gas through both left and right ends of the installation region can be suppressed, the flow of the combustion exhaust gas near the U-shaped pipe portion that is arranged at both left and right ends in the lateral direction of the installation region and has inferior heat transfer efficiency compared to the straight pipe portion can be suppressed. Therefore, heat can be efficiently recovered from the combustion exhaust gas in the secondary heat exchanger.

[0013] (3) Preferably, the through hole is arranged on the opening side of the partition portion.

[0014] With such a configuration, the combustion exhaust gas can be guided from the installation region to the upper region at the opening side of the housing by the through hole. Since the combustion exhaust gas that has passed from the gas inlet to the opening side of the housing has had a certain amount of heat recovered by the plurality of heat transfer tubes, a reduction in heat transfer efficiency associated with the formation of the through hole can be suppressed. In other words, it is possible to prevent the combustion exhaust gas passing through the gas inlet side of the housing, where sufficient heat has not been recovered by the plurality of heat transfer tubes, from being excessively guided to the upper region, and a reduction in heat transfer efficiency can be suppressed.

[0015] (4) A plurality of protrusion portions are formed on the partition portion so as to protrude downward from the lower surface of the partition portion and extend in a direction intersecting the extending direction of the plurality of straight pipe portions, and preferably, the protrusion portions are in contact with the straight pipe portion arranged at the uppermost stage from above.

[0016] With such a configuration, the straight pipe portion can be held by the protrusion portion, and the posture of the heat transfer tubes in the housing can be stabilized. In addition, since a gap can be secured between the heat transfer tube located at the uppermost stage and the partition portion, the combustion exhaust gas can pass through this gap, and the combustion exhaust gas near the heat transfer tube at the uppermost stage can be smoothly circulated.

[0017] <Embodiment 1> Hereinafter, Embodiment 1 will be described with reference to FIGS. 1 to 16. Note that, for a plurality of identical members, only some of the members may be assigned reference numerals, and the reference numerals of other members may be omitted.

[0018] [Overall Structure of Water Heater] FIG. 1 is a front view of the water heater 1 as seen from the front, showing a state where the front cover on the front side is removed. FIGS. 2 and 3 are views showing the inner cylinder 3 which is a main component arranged inside the outer casing 2 of the water heater 1. As shown in FIGS. 1 to 3, the water heater 1 includes a burner device 4, a primary heat exchanger 10, a secondary heat exchanger 20, a path member 50, a water inlet pipe 13, a hot water outlet pipe 14, a relay pipe 15, etc., and has a function of heating the tap water supplied from the outside and discharging hot water. The burner device 4 burns combustion gas to generate combustion exhaust gas. The combustion exhaust gas generated by the burner device 4 passes through the primary heat exchanger 10, then through the path member 50, and is sent to the secondary heat exchanger 20 and discharged to the outside of the water heater 1. In the primary heat exchanger 10, the sensible heat of the combustion exhaust gas is recovered, and in the secondary heat exchanger 20, the latent heat of the combustion exhaust gas is recovered.

[0019] The water inlet pipe 13 is configured as a path through which water is supplied, and as shown in FIG. 3, it is connected to the first header 37 of the secondary heat exchanger 20. As shown in FIGS. 9 and 10, the first header 37 is connected to a plurality of heat transfer pipes 21 housed in the housing 22. The ends of the plurality of heat transfer pipes 21 on the side opposite to the first header 37 are connected to the second header 38. As shown in FIG. 3, the second header 38 is connected to the primary heat transfer pipe 12 arranged inside the primary heat exchanger 10 via the relay pipe 15. As shown in FIGS. 1 and 2, the end of the primary heat transfer pipe 12 of the primary heat exchanger 10 on the side opposite to the relay pipe 15 is connected to the hot water outlet pipe 14. The hot water outlet pipe 14 is configured as a path for sending out hot water. That is, in the water heater 1, the water flowing in from the water inlet pipe 13 flows in the order of the plurality of heat transfer pipes 21 of the secondary heat exchanger 20, the relay pipe 15, and the primary heat transfer pipe 12 of the primary heat exchanger 10. Then, the water flowing through the plurality of heat transfer pipes 21 of the secondary heat exchanger 20 and the primary heat transfer pipe 12 of the primary heat exchanger 10 receives the heat of the combustion exhaust gas and is heated, and flows out as hot water from the hot water outlet pipe 14.

[0020] As shown in FIG. 1, the water heater 1 is provided with a drain hose 5. The upstream side of the drain hose 5 is connected to a drain outlet 26 (see FIG. 2) of the secondary heat exchanger 20 described later, and the downstream side is connected to a neutralizer. The drain generated by the recovery of the latent heat of the combustion exhaust gas in the secondary heat exchanger 20 is discharged to the outside of the secondary heat exchanger 20 through the drain outlet 26 and sent to the neutralizer through the drain hose 5.

[0021] As shown in FIG. 1, the water heater 1 is provided with a controller 6 as a control device. The controller 6 is configured as, for example, a known microcomputer or the like, and is configured to be able to acquire signals from various sensors provided in the water heater 1, and to be able to control various actuators provided in the water heater 1. For example, when the water heater 1 detects the water flow in the water inlet pipe 13 by a water flow sensor (not shown), it operates the burner device 4 to generate hot water.

[0022] [Primary Heat Exchanger] As shown in FIGS. 2 and 3, the primary heat exchanger 10 includes a can body 11 and primary heat transfer tubes 12. The can body 11 has a substantially rectangular shape in plan view that is long in the left-right direction and is formed in a cylindrical shape that penetrates vertically. The primary heat transfer tubes 12 of the primary heat exchanger 10 are arranged inside the can body 11 and include a plurality of straight tubes extending in the front-rear direction and connecting tubes that connect the front end portions or the rear end portions of two straight tubes adjacent to each other in the left-right direction outside the can body 11. The plurality of straight tubes are connected in series via the connecting tubes. That is, the primary heat transfer tubes 12 of the primary heat exchanger 10 are formed in a meandering shape as a whole. The can body 11 and the primary heat transfer tubes 12 can be made of copper with excellent thermal conductivity.

[0023] The primary heat exchanger 10 is fixed to the upper end portion of the burner device 4 and is arranged such that the combustion exhaust gas generated by the burner device 4 passes through the inside of the can body 11 of the primary heat exchanger 10 from below to above. Further, a path member 50, which will be described later, is fixed to the upper end portion of the primary heat exchanger 10, and the combustion exhaust gas from which sensible heat has been recovered by the primary heat exchanger 10 is sent to the path member 50.

[0024] As shown in FIG. 3, a relay pipe 15 is connected to the opening at the rear and right end of the primary heat transfer tube 12 so that water from the secondary heat exchanger 20 flows in. As shown in FIG. 2, a hot water outlet pipe 14 is connected to the opening at the front and left side of the primary heat transfer tube 12 so that the heated water flows out. That is, in the primary heat exchanger 10, the water that has flowed in from the rear surface side on the right side of the can body 11 through the relay pipe 15 exchanges heat with the combustion exhaust gas passing through the inside of the can body 11 while meandering inside the primary heat transfer tube 12 and is heated. Then, the heated hot water flows into the hot water outlet pipe 14 from the front surface side on the left side of the can body 11.

[0025] [Secondary heat exchanger] Next, the configuration of the secondary heat exchanger 20 will be described in detail. As shown in FIGS. 1 to 3, the secondary heat exchanger 20 is disposed above the primary heat exchanger 10. The secondary heat exchanger 20 and the primary heat exchanger 10 are connected by a path member 50 for introducing the combustion exhaust gas that has passed through the primary heat exchanger 10 into the secondary heat exchanger 20.

[0026] As shown in FIG. 5, the secondary heat exchanger 20 includes a plurality (seven in this embodiment) of heat transfer tubes 21 and a housing 22 in which the plurality of heat transfer tubes 21 are disposed inside. The plurality of heat transfer tubes 21 and the housing 22 can be made of stainless steel with excellent corrosion resistance.

[0027] [Housing] As shown in FIG. 12, the housing 22 includes a bottomed box-shaped housing main body portion 23 that is open at the top, a lid body 24 that closes the housing main body portion 23 from above, and a partition portion 25 disposed inside the housing 22. The central positions of the housing 22, the lid body 24, the housing main body portion 23, and the partition portion 25 in the left-right direction are substantially coincident. As shown in FIG. 15, the housing main body portion 23 includes a bottom wall portion 23A, a front wall portion 23B that rises from the front edge of the bottom wall portion 23A, a rear wall portion 23C that rises from the rear edge of the bottom wall portion 23A, a right wall portion 23D that rises from the right edge of the bottom wall portion 23A, and a left wall portion 23E that rises from the left edge of the bottom wall portion 23A. The front wall portion 23B, the right wall portion 23D, the rear wall portion 23C, and the left wall portion 23E constitute the peripheral wall portion of the housing main body portion 23. A drain discharge port 26 that penetrates the bottom wall portion 23A in the vertical direction is provided in the front side portion of the bottom wall portion 23A. As shown in FIG. 5, in the water heater 1, the bottom wall portion 23A is arranged to incline downward as it goes forward, so that the drain generated due to the latent heat recovery in the secondary heat exchanger 20 is easily discharged to the drain discharge port 26.

[0028] As shown in Fig. 12, a fixing portion 27 for clamping and fixing the lid body 24 to the housing main body portion 23 is provided at the upper end portion of the peripheral wall portion of the housing main body portion 23. As shown in Fig. 15, the fixing portion 27 has a flange portion 27A that extends outward in a flange shape from the upper end peripheral edge portion of the peripheral wall portion, and a clamping portion 27B that extends upward from the outer edge portion of the flange portion 27A. As shown in Fig. 6, the clamping portion 27B is a portion that deforms when the lid body 24 is clamped to the housing main body portion 23. In a state where the lid body 24 is clamped to the housing main body portion 23, the clamping portion 27B deforms so as to sandwich the fixed portion 24A provided at the outer peripheral edge portion of the lid body 24 together with the flange portion 27A in the vertical direction. Further, an annular packing 27C is interposed between the fixed portion 24A and the clamping portion 27B, preventing the passage of gas between the lid body 24 and the housing main body portion 23.

[0029] [Gas inlet] As shown in Fig. 15, a gas inlet 28 penetrating in the front-rear direction is formed in the rear wall portion 23C of the housing main body portion 23. The gas inlet 28 is an opening for introducing combustion exhaust gas into the interior of the housing 22. A plurality of connected portions 29 are formed at the peripheral edge portion of the gas inlet 28 in the rear wall portion 23C. The connected portions 29 have a female screw shape, and as shown in Figs. 6 and 8, the path member 50 is to be attached. That is, combustion exhaust gas is introduced into the interior of the housing 22 from the path member 50 through the gas inlet 28.

[0030] As shown in Fig. 9, a right opening 33 penetrating in the left-right direction is formed in the right wall portion 23D of the housing main body portion 23. The right opening 33 is an opening for housing a plurality of heat transfer tubes 21 assembled to an assembly 35 described later. A plurality of connected portions 34 are formed around the right opening 33 in the right wall portion 23D. The connected portions 34 have a female screw shape and are used for attaching the assembly 35.

[0031] [A plurality of heat transfer tubes] As shown in Fig. 9, the assembly 35 includes a plurality of heat transfer tubes 21, a plate-shaped closing member 36, a first header 37, and a second header 38. As shown in Fig. 11, the heat transfer tubes 21 extend in a meandering manner along a predetermined planar direction. Each of the heat transfer tubes 21 has a common shape. The heat transfer tube 21 has a plurality (six in this embodiment) of straight tube portions 21A, at least one (five in this embodiment) of U-shaped tube portions 21B, a first connection portion 21C, and a second connection portion 21D.

[0032] [Straight tube portion, U-shaped tube portion] Each of the plurality of straight tube portions 21A is arranged in parallel in a direction (front-rear direction) orthogonal to the direction (left-right direction) in which the plurality of straight tube portions 21A extend. The end portions of two adjacent straight tube portions 21A in the front-rear direction are connected by a U-shaped tube portion 21B that bends in a U shape. However, the right end portions of the straight tube portion 21A arranged in the frontmost row and the straight tube portion 21A arranged in the last row are not connected to the U-shaped tube portion 21B and are open to the right. The right end portion of the straight tube portion 21A in the frontmost row is the first connection portion 21C, and the right end portion of the straight tube portion 21A in the last row is the second connection portion 21D. The plurality of straight tube portions 21A and the U-shaped tube portions 21B are alternately connected from the first connection portion 21C to the second connection portion 21D, whereby the heat transfer tubes 21 are connected in series.

[0033] As shown in Fig. 9, the plurality of heat transfer tubes 21 are fixed to the closing member 36 in a state of being stacked in the vertical direction and are housed in the housing 22. As shown in Fig. 5, in a state where the plurality of heat transfer tubes 21 are arranged inside the housing 22, the plurality of straight tube portions 21A extend in the left-right direction and are arranged at intervals in the vertical direction and the front-rear direction. More specifically, two adjacent heat transfer tubes 21 in the vertical direction are arranged offset from each other in the front-rear direction, and the plurality of straight tube portions 21A are arranged in a staggered pattern as a whole in a side sectional view. Among the plurality of heat transfer tubes 21, since the straight tube portions 21A are arranged orthogonal to the flow direction of the combustion exhaust gas (mainly the front-rear direction and the vertical direction), the heat exchange between the water flowing through the plurality of heat transfer tubes 21 and the combustion exhaust gas is mainly performed in the straight tube portions 21A.

[0034] As shown in FIG. 9, the closing member 36 is a plate-like member for closing the right opening 33 from the right in a state where a plurality of heat transfer tubes 21 are housed in the housing 22. As shown in FIG. 10, the closing member 36 has a first through hole through which the first connection portions 21C of the plurality of heat transfer tubes 21 are inserted, a second through hole through which the second connection portions 21D of the plurality of heat transfer tubes 21 are inserted, and an insertion hole through which the connecting member 36A is inserted, which are formed to penetrate in the left-right direction. A burring portion is provided in the first through hole, and the first connection portion 21C is fixed to the closing member 36 by brazing or the like in a state of being inserted into the first through hole. Similarly, the second connection portion 21D is also fixed to the closing member 36 by brazing or the like in a state of being inserted into the second through hole. As shown in FIG. 9, the insertion hole is provided at a position corresponding to the connected portion 34, and the closing member 36 is fixed to the right wall portion 23D by connecting the connecting member 36A inserted into the insertion hole to the connected portion 34. An annular packing 36B is provided between the right wall portion 23D and the closing member 36. Thereby, the passage of gas between the right wall portion 23D and the closing member 36 is prevented.

[0035] As shown in FIG. 3, the first header 37 is a portion connecting the inlet of the secondary heat exchanger 20 (specifically, the opening of the first connection portions 21C of the plurality of heat transfer tubes 21) and the downstream side of the water inlet pipe 13. As shown in FIG. 10, the first header 37 includes a first header body 37A fixed to the closing member 36, a first header lid 37B covering the opening of the first header body 37A, and a joint cylinder 37C. The first header body 37A has a first bottom hole 37D through which the first connection portion 21C inserted into the closing member 36 is inserted. The first header lid 37B has a first lid hole 37E to which the joint cylinder 37C is attached. The joint cylinder 37C is a portion connected to the downstream side of the water inlet pipe 13.

[0036] As shown in FIG. 3, the second header 38 is a portion that connects the outlet of the secondary heat exchanger 20 (specifically, the opening of the second connection portion 21D of the plurality of heat transfer tubes 21) and the pipe on the inlet side of the primary heat exchanger 10 (specifically, the upstream end of the relay pipe 15). As shown in FIG. 10, the second header 38 includes a second header main body 38A fixed to the closing member 36, a second header lid 38B that covers the opening of the second header main body 38A, and a joint cylinder 38C. The second header main body 38A has a second bottom hole 38D through which the second connection portion 21D inserted through the closing member 36 is inserted. The second header lid 38B has a second lid hole 38E to which the joint cylinder 38C is attached. The joint cylinder 38C is a portion connected to the upstream side of the relay pipe 15. As a method for assembling each of the headers 37 and 38 and fixing each of the headers 37 and 38 to the closing member 36 and the like, brazing, welding, or the like can be used.

[0037] In the secondary heat exchanger 20, the water supplied from the water inlet pipe 13 is passed in parallel from the first connection portion 21C of each heat transfer tube 21 via the first header 37. The water flow exchanges heat with the combustion exhaust gas flowing in the housing 22 while flowing in a meandering shape through each heat transfer tube 21. The water flow heated by the heat exchange flows into the relay pipe 15 from the second connection portion 21D via the second header 38.

[0038] [Gas outlet] As shown in FIG. 12, the lid 24 is a plate-like member and includes a bulging portion 39 that bulges upward at the central portion and a fixed portion 24A disposed at the outer edge of the bulging portion 39. A gas outlet 41 penetrating in the vertical direction is formed on the top surface of the bulging portion 39. As shown in FIG. 4, the gas outlet 41 is located at the center position in the left-right direction and closer to the front in the housing 22. As shown in FIG. 5, a cylindrical exhaust pipe 42 protruding upward is provided at the peripheral edge of the gas outlet 41. The combustion exhaust gas from which latent heat has been recovered in the secondary heat exchanger 20 is discharged to the outside through the gas outlet 41. Specifically, the combustion exhaust gas is discharged to the outside through an exhaust pipe portion (not shown) connected to the exhaust pipe 42.

[0039] As shown in FIG. 12, when the lid body 24 is clamped and fixed to the housing main body 23, the fixed portion 24A is disposed above the flange portion 27A of the housing main body 23 and is clamped by the clamping portion 27B. As shown in FIG. 6, the fixed portion 24A is sandwiched in the vertical direction by the flange portion 27A and the clamping portion 27B. By clamping and fixing the lid body 24 to the housing main body 23, the housing main body 23 is closed.

[0040] [Partition portion] As shown in FIG. 5, the partition portion 25 is a plate-like member fixed to the lower surface of the lid body 24, and vertically partitions the internal space S1 formed by the housing main body 23 and the lid body 24. Specifically, the partition portion 25 partitions the internal space S1 into a disposition region S2 where a plurality of heat transfer tubes 21 are disposed, and an upper region S3 disposed on the lid body 24 side (upper side) than the disposition region S2. The upper region S3 communicates with the gas outlet 41 above. The disposition region S2 and the upper region S3 communicate with each other through an opening 46 and a plurality of through holes 43A described later.

[0041] [A plurality of through holes] As shown in FIG. 14, the partition portion 25 includes a bottom plate 43, extending portions 44 extending upward from the left and right edge portions and the rear edge portion of the bottom plate 43, and a fixing piece 45 extending upward from the front edge portion of the bottom plate 43. The bottom plate 43 has a rectangular plate shape. A plurality (22 in this embodiment) of through holes 43A penetrating in the vertical direction are formed in the bottom plate 43. The plurality of through holes 43A are arranged in two rows in the front-rear direction in a substantially one-third region on the front side of the bottom plate 43 and are arranged closer to the left and right centers. As shown in FIG. 4, in the housing 22, a part of the plurality of through holes 43A is disposed directly below the gas outlet 41. As shown in FIG. 5, the plurality of through holes 43A communicate the disposition region S2 and the upper region S3. The bottom plate 43 is disposed at a distance below the lid body 24.

[0042] [A plurality of protruding portions] As shown in Fig. 13, the partition portion 25 includes a plurality (seven in this embodiment) of protrusion portions 43B that protrude downward from the lower surface of the bottom plate 43. The protrusion portions 43B are formed elongated in the front-rear direction. That is, the protrusion portions 43B extend in a direction orthogonal to the left-right direction, which is the extending direction of the straight pipe portion 21A. The plurality of protrusion portions 43B are arranged at the front side portion and the rear side portion of the bottom plate 43. Two front protrusion portions 43B are provided and arranged on both the left and right sides of the plurality of through holes 43A. Five rear protrusion portions 43B are provided and arranged at intervals in the left-right direction.

[0043] As shown in Fig. 7, in a state where a plurality of heat transfer pipes 21 are housed in the housing 22, the plurality of protrusion portions 43B are adapted to contact the straight pipe portion 21A arranged at the uppermost stage from above. Specifically, the front protrusion portions 43B are in contact with the straight pipe portion 21A at the uppermost stage of the front side (specifically, the second row from the front), and the rear protrusion portions 43B are in contact with the straight pipe portion 21A at the uppermost stage of the rear side (specifically, the fifth row from the front). Thereby, as shown in Fig. 5, the plurality of heat transfer pipes 21 are clamped vertically by the protrusion portions 43B and the bottom wall portion 23A of the housing main body portion 23, so that the plurality of heat transfer pipes 21 can be stably held in the housing 22.

[0044] As shown in Fig. 7, the protrusion portion 43B protrudes downward from the bottom plate 43, and the protrusion portion 43B is formed in an elongated shape in a direction orthogonal to the extending direction of the straight pipe portion 21A. Therefore, a gap CL is formed between the bottom plate 43 and the straight pipe portion 21A at the uppermost stage. Specifically, this gap CL spreads around the protrusion portion 43B below the bottom plate 43 and above the straight pipe portion 21A at the uppermost stage. Thereby, the combustion exhaust gas can pass through the gap CL, that is, above the straight pipe portion 21A at the uppermost stage. Therefore, it is difficult for the combustion exhaust gas to stay above the straight pipe portion 21A at the uppermost stage, and it is possible to suppress an excessive increase in the exhaust resistance of the combustion exhaust gas. In addition, since the gap CL is provided between the straight pipe portion 21A at the uppermost stage and the bottom plate 43, the through hole 43A penetrating the bottom plate 43 is not blocked by the straight pipe portion 21A at the uppermost stage. Therefore, the combustion exhaust gas can be guided from the arrangement region S2 to the upper region S3 through the through hole 43A.

[0045] As shown in FIG. 14, the extended portion 44 includes a laterally extended portion 44A extending from both left and right end portions of the bottom plate 43, and a rearward extended portion 44B extending from the rear edge portion of the bottom plate 43. The laterally extended portion 44A rises upward substantially vertically from the bottom plate 43. The rearward extended portion 44B includes a portion that rises upward substantially vertically from the bottom plate 43, and a first fixing portion 44C that further extends rearward from the upper end portion of the rising portion.

[0046] In the present embodiment, the fixing piece 45 includes a second fixing portion 45A having a long shape in the left - right direction, and three extending portions 45B that extend obliquely downward rearward from the second fixing portion 45A and are connected to the bottom plate 43. The extending portions 45B are arranged at the left - right center position, the left - end side, and the right - end side of the second fixing portion 45A. Note that, different from the present embodiment, a plurality of fixing pieces may be provided at intervals in the left - right direction at the front edge portion of the bottom plate, and each fixing piece may have a configuration including one second fixing portion and one extending portion.

[0047] [Opening] In a state where the partition portion 25 is fixed to the lid body 24, as shown in FIG. 13, the front edge portions of the lid body 24 and the partition portion 25 constitute an opening 46 that is open in the front - rear direction. The space (upper region S3) between the lid body 24 and the partition portion 25 opens forward through the opening 46. As shown in FIG. 5, the opening 46 connects the upper region S3 and the arrangement region S2. Also, the upper region S3 is closed by the rearward extended portion 44B at the rear. As shown in FIG. 13, the upper region S3 is defined by the laterally extended portions 44A on both sides. Therefore, as shown in FIG. 5, the arrangement region S2 and the upper region S3 are connected through the opening 46 and the plurality of through - holes 43A. The combustion exhaust gas introduced into the housing 22 from the gas inlet 28 passes forward through the arrangement region S2, flows into the upper region S3 through the opening 46 or the through - hole 43A, and is finally discharged from the gas outlet 41.

[0048] As shown in FIG. 5, the opening 46 is arranged in front of the plurality of heat transfer tubes 22 inside the housing 22. Therefore, the opening 46 allows the combustion exhaust gas that has reached the vicinity of the frontmost straight tube portion 21A of the plurality of heat transfer tubes 21 to pass from the arrangement region S2 to the upper region S3. For this reason, heat can be recovered even in the frontmost straight tube portion 21A, and the efficiency of heat transfer from the combustion exhaust gas to the water flowing through the plurality of heat transfer tubes 21 can be improved.

[0049] On the other hand, as shown in FIG. 5, the plurality of through holes 43A of the partition portion 25 are arranged behind the opening 46 inside the housing 22 and above the front portion of the plurality of heat transfer tubes 21. For this reason, a part of the combustion exhaust gas that has reached the front side of the arrangement region S2 from the gas inlet 28 is recovered in heat quantity by the water flowing through the plurality of heat transfer tubes 21 in the vicinity, and then flows from the arrangement region S2 to the upper region S3 through the plurality of through holes 43A behind the frontmost straight tube portion 21A. That is, the exhaust path that flows from the arrangement region S2 to the upper region S3 through the plurality of through holes 43A is shorter than the exhaust path that flows from the arrangement region S2 to the upper region S3 through the opening 46 provided on the front side inside the housing 22, and is a so-called shortcut exhaust path. The combustion exhaust gas passing through the shortcut exhaust path is only a very small part of the whole, and most of the combustion exhaust gas passes through the space on the front side of the arrangement region S2 and flows to the upper region S3 through the opening 46. Nevertheless, by providing the plurality of through holes 43A in the partition portion 25, an increase in the exhaust resistance of the combustion exhaust gas can be suppressed, and the combustion performance of the water heater 1 can be ensured.

[0050] In addition, since the plurality of through holes 43A are arranged on the opening 46 side (front side) of the partition portion 25, specifically, in the front approximately one-third region of the bottom plate 43, even when the combustion exhaust gas flows through the shortcut exhaust path passing through the through holes 43A, the combustion exhaust gas passes through the vicinity of many straight tube portions 21A (specifically, the straight tube portions 21A included in the region from the last row to about the eighth row) arranged behind the through holes 43A in the arrangement region S2. Therefore, a decrease in the heat efficiency of the secondary heat exchanger 20 can be suppressed as much as possible.

[0051] Furthermore, since the plurality of through holes 43A are arranged closer to the center in the left - right direction of the partition portion 25, the combustion exhaust gas is deflected so as to flow closer to the center in the left - right direction of the housing 22. As a result, a large amount of combustion exhaust gas can flow in the vicinity of the straight pipe portion 21A arranged at a position excluding both the left and right sides of the heat transfer pipe 21. At the same time, it is possible to suppress the flow of combustion exhaust gas in the vicinity of the U - shaped pipe portion 21B arranged on both the left and right sides of the heat transfer pipe 21. Since the straight pipe portion 21A extending in a direction orthogonal to the direction in which the combustion exhaust gas flows has better heat transfer efficiency than the U - shaped pipe portion 21B not arranged in such a manner, the heat transfer efficiency of the secondary heat exchanger 20 as a whole can be improved.

[0052] As shown in FIG. 5, the path member 50 is arranged between the primary heat exchanger 10 and the secondary heat exchanger 20. The path member 50 communicates the upper - end opening of the can body 11 of the primary heat exchanger 10 and the gas inlet 28 of the rear - wall portion 23C of the housing 22 of the secondary heat exchanger 20, and constitutes a flow - through space S4 through which the combustion exhaust gas flows.

[0053] As shown in FIG. 16, the path member 50 is configured to have a path member main body 51 and a path member rear portion 52. The path member main body 51 is formed in a shape that gradually becomes higher from the front end portion toward the rear in the front - rear direction and bulges upward. The rear end of the path member main body 51 is open rearward, and a plurality of connected portions are provided at the periphery of this opening. The plurality of connected portions are in the shape of female threads and are configured to be connected to the connecting member 52A. The path member rear portion 52 is formed in a square - dish shape that bulges rearward. The path member rear portion 52 has an insertion hole at a position corresponding to the connected portion of the path member main body 51, and the connecting member 52A inserted through this insertion hole is configured to be connected to the connected portion of the path member main body 51. As a result, as shown in FIG. 8, the path member rear portion 52 is fixed to the path member main body 51 so as to close the rear - end opening of the path member main body 51. A packing (not shown) is provided between the path member main body 51 and the path member rear portion 52 to prevent the passage of gas between the path member main body 51 and the path member rear portion 52.

[0054] As shown in FIG. 8, the rear portion 52 of the path member has an insertion hole at a position corresponding to the connected portion 29 of the rear wall portion 23C. By connecting the connecting member 52B inserted through this insertion hole to the connected portion 29, the rear portion 52 of the path member is fixed to the rear wall portion 23C. An annular packing 52C is provided between the rear wall portion 23C and the rear portion 52 of the path member. The packing 52C prevents gas leakage between the rear wall portion 23C and the rear portion 52 of the path member.

[0055] As shown in FIG. 16, an opening 53 that opens forward is provided in the upper portion of the rear portion 52 of the path member. As shown in FIG. 5, the opening 53 is the terminal end of the flow space S4 of the path member 50. The flow space S4 extends obliquely upward in front as it approaches the opening 53, that is, as it approaches the terminal end side. In a state where the path member 50 is attached to the housing 22, the opening 53 communicates with the gas inlet 28.

[0056] [Operational Effects of Embodiment 1] As described above, the water heater 1 of Embodiment 1 includes a primary heat exchanger 10 for recovering sensible heat, and a secondary heat exchanger 20 disposed above the primary heat exchanger 10. The secondary heat exchanger 20 includes a plurality of heat transfer tubes 21 and a housing 22 in which the plurality of heat transfer tubes 21 are disposed. Each of the plurality of heat transfer tubes 21 includes a plurality of straight tube portions 21A extending in the left-right direction and a plurality of U-shaped tube portions 21B connecting the ends of two adjacent straight tube portions 21A. With the plurality of heat transfer tubes 21 disposed inside the housing 22, the plurality of straight tube portions 21A are arranged at intervals in the vertical and front-rear directions. The housing 22 has a gas inlet 28 at the rear and a gas outlet 41 at the upper part. The housing 22 includes a partition portion 25 that partitions the internal space S1 of the housing 22 into a disposition region S2 where the plurality of heat transfer tubes 21 are disposed and an upper region S3 disposed above the disposition region S2 and communicating with the gas outlet 41. An opening 46 is formed in the housing 22 in front of the plurality of heat transfer tubes 21 to connect the disposition region S2 and the upper region S3. The water heater 1 guides the combustion exhaust gas introduced into the disposition region S2 through the gas inlet 28 forward and then through the opening 46 into the upper region S3, and discharges it to the outside through the gas outlet 41. The partition portion 25 has a plurality of through holes 43A that penetrate the partition portion 25 in the vertical direction and communicate the disposition region S2 and the upper region S3.

[0057] According to such a configuration, by providing the through holes 43A in the partition portion 25, a part of the combustion exhaust gas flowing through the disposition region S2 can be guided to the upper region S3, so that an excessive increase in exhaust resistance can be suppressed and the combustion performance of the water heater 1 can be ensured.

[0058] In Embodiment 1, the gas outlet 41 is located near the center in the left-right direction of the housing 22, and the through holes 43A are disposed near the center in the left-right direction of the partition portion 25.

[0059] With such a configuration, since the combustion exhaust gas flowing through both left and right ends in the lateral direction of the installation region S2 can be deflected toward the central portion in the lateral direction, the combustion exhaust gas easily flows near the straight pipe portion 21A that is arranged closer to the central portion in the lateral direction of the installation region S2 and has better heat transfer efficiency than the U-shaped pipe portion 21B. Further, since the flow of the combustion exhaust gas through both left and right ends of the installation region S2 can be suppressed, the flow of the combustion exhaust gas near the U-shaped pipe portion 21B that is arranged at both ends in the lateral direction of the installation region S2 and has inferior heat transfer efficiency compared to the straight pipe portion 21A can be suppressed. Therefore, heat can be efficiently recovered from the combustion exhaust gas in the secondary heat exchanger 20.

[0060] In Embodiment 1, the through hole 43A is arranged on the opening 46 side of the partition portion 25.

[0061] With such a configuration, the combustion exhaust gas can be guided from the installation region S2 to the upper region S3 at the opening 46 side of the housing 22 by the through hole 43A. Since the combustion exhaust gas passing from the gas inlet 28 to the opening 46 side of the housing 22 has had a certain amount of heat recovered by the plurality of heat transfer tubes 21, a reduction in heat transfer efficiency associated with the formation of the through hole 43A can be suppressed. In other words, it is possible to prevent the combustion exhaust gas passing through the gas inlet 28 side of the housing 22, where sufficient heat has not been recovered by the plurality of heat transfer tubes 21, from being excessively guided to the upper region S3, and a reduction in heat transfer efficiency can be suppressed.

[0062] In Embodiment 1, the partition portion 25 is formed with a plurality of protruding ridges 43B that protrude downward from the lower surface of the partition portion 25 and extend in a direction intersecting the extending direction of the plurality of straight pipe portions 21A, and the protruding ridges 43B are in contact with the straight pipe portion 21A arranged at the uppermost stage from above.

[0063] With such a configuration, the straight pipe portion 21A can be held by the protruding ridge 43B, and the posture of the heat transfer tube 21 in the housing 22 can be stabilized. In addition, since a gap CL can be secured between the heat transfer tube 21 located at the uppermost stage and the partition portion 25, the combustion exhaust gas can pass through this gap CL, and the combustion exhaust gas near the heat transfer tube 21 at the uppermost stage can be smoothly circulated.

[0064] <Other Embodiments> The present disclosure is not limited to the embodiments described by the above description and drawings. For example, the features of the above-described or below-described embodiments can be combined in any combination within a non-contradictory range. Also, any feature of the above-described or below-described embodiments can be omitted if it is not explicitly specified as essential. Furthermore, the above-described embodiments may be modified as follows.

[0065] In the above embodiment, the plurality of through holes 43A were arranged near the center in the left-right direction of the partition portion 25 and on the opening 46 side of the partition portion 25, but the arrangement of the plurality of through holes in the partition portion may be changed.

[0066] In the above embodiment, the water heater 1 having a hot water supply circuit for heating tap water to discharge hot water was exemplified, but a water heater for other uses such as circulation for a bath or central heating may also be used.

[0067] Note that the scope of the present disclosure is not limited to the above embodiments, and it is intended that all modifications within the scope shown by the claims or within the scope equivalent to the claims are included.

Description of Reference Numerals

[0068] 1... Water heater, 2... Outer casing, 3... Inner cylinder, 4... Burner device, 5... Drain hose, 6... Controller, 10... Primary heat exchanger, 11... Cylinder body, 12... Primary heat transfer tube, 13... Water inlet pipe, 14... Hot water outlet pipe, 15... Relay pipe 20... Secondary heat exchanger 21…Heat transfer tube, 21A…Straight tube portion, 21B…U-shaped tube portion, 21C…First connection portion, 21D…Second connection portion, 22…Housing, 22A…Housing main body portion, 22B…Bottom wall portion, 22C…Front wall portion, 22D…Rear wall portion, 22E…Right wall portion, 22F…Left wall portion, 23…Cover body, 23A…Fixed portion, 24…Partition portion, 25…Drain outlet, 26…Fixing portion, 26A…Flange portion, 26B…Crimping portion, 26C…Packing, 27…Gas inlet, 28…Connected portion, 29…Right side opening, 30…Connected portion, 31…Assembly, 32…Blocking member, 32A…Connecting member, 32B…Packing, 33…First header, 33A…First header main body, 33B…First header cover, 33C…Joint cylinder, 33D…First bottom hole, 33E…First cover hole, 34…Second header, 34A…Second header main body, 34B…Second header cover, 34C…Joint cylinder, 34D…Second bottom hole, 34E…Second cover hole, 35…Bulging portion, 36…Gas outlet, 37…Exhaust cylinder, 38…Bottom plate, 38A…Through hole, 38B…Ridge portion, 39…Extended portion, 39A…Lateral extended portion, 39B…Rear extended portion, 39C…First fixing portion, 40…Fixing piece, 40A…Second fixing portion, 40B…Extended portion, 41…Opening, CL…Gap, S1…Internal space, S2…Arrangement region, S3…Upper region 50…Path member 51…Path member main body, 52…Rear portion of path member, 52A…Connecting member, 52B…Connecting member, 52C…Packing, 53…Opening, S4…Flow space

Claims

1. A primary heat exchanger for recovering sensible heat and a secondary heat exchanger disposed above the primary heat exchanger, The secondary heat exchanger includes a plurality of heat transfer tubes and a housing in which the plurality of heat transfer tubes are disposed, Each of the plurality of heat transfer tubes includes a plurality of straight tube portions extending in the left-right direction and a plurality of U-shaped tube portions connecting ends of two adjacent straight tube portions, When the plurality of heat transfer tubes are disposed inside the housing, the plurality of straight tube portions are arranged at intervals in the up-down direction and the front-rear direction, The housing has a gas inlet at a rear portion and a gas outlet at an upper portion, the housing includes a partition that divides an internal space of the housing into an arrangement region in which the plurality of heat transfer tubes are arranged and an upper region that is arranged above the arrangement region and communicates with the gas outlet, an opening is formed in the housing, the opening being disposed forward of the plurality of heat transfer tubes and connecting the arrangement region and the upper region; A water heater in which a combustion exhaust gas introduced into the installation area through the gas inlet is guided forward, then guided into the upper area through the opening, and discharged to the outside through the gas outlet, The partition portion has a plurality of through holes that pass through the partition portion in the vertical direction and communicate the installation area with the upper area.

2. The gas outlet is located toward a center portion in a left-right direction of the housing, The water heater according to claim 1 , wherein the through hole is disposed toward a center portion in a left-right direction of the partition portion.

3. The water heater according to claim 1 or 2, wherein the through hole is disposed on the opening side of the partition portion.

4. The partition portion is formed with a plurality of protrusions that protrude downward from a lower surface of the partition portion and extend in a direction intersecting with a direction in which the plurality of straight pipe portions extend, The water heater according to claim 1 , wherein the protrusion portion abuts from above against the straight pipe portion arranged at the uppermost stage.

Images