Heat exchanger and water heating device equipped with the same

Abstract

To provide a heat exchanger which can prevent a considerable rise of a temperature of a sidewall part of a case caused by an influence of a heating gas such as a combustion gas.SOLUTION: In a heat exchanger HE having an auxiliary member 8a including a body pipe joining part 80 joined to a body pipe 5, and an extension part 81 extending toward sides of a plurality of fins 4 from the body pipe joining part 80, the plurality of fins 4 are arranged separately from a sidewall part 22a so as not to directly contact with the sidewall part 22a of a case 2, the extension part 81 of the auxiliary member 8a includes an entry part 81a which enters a clearance between the plurality of fins 4 and the sidewall part 22a, and a first abutment part C1 arranged at the entry part 81a, and abutting on outer end parts 40 of the plurality of fins 4. The first abutment part C1 is spaced apart from the sidewall part 22a, and a space part 9 which is suppressed in the flow-in of a heating gas is formed between the first abutment part C1 and the sidewall part 22a.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a heat exchanger of a type that recovers heat from a heating gas such as combustion gas, and to a hot water apparatus such as a water heater that is equipped with the heat exchanger. [Background technology]

[0002] Examples of water heating devices are described in Patent Documents 1 and 2, respectively. The water heating device described in Patent Document 1 includes a burner and a heat exchanger. The heat exchanger includes a case into which combustion gas generated by the burner is supplied, a heat transfer tube with multiple fins arranged within the case, and a body pipe. The body pipe is located within the case upstream of the heat transfer tube and multiple fins in the direction of combustion gas flow and in contact with the side wall of the case, cooling the side wall and preventing thermal damage to the side wall. Hot water flowing through the body pipe and the heat transfer tube is heated by the combustion gas and produced as hot water.

[0003] However, in the water heater described above, the outer ends of the fins are in contact with the sidewall of the case, but these contact areas are spaced apart from the main pipe, reducing the cooling effect of the main pipe. This can lead to heat transfer from the fins to the sidewall of the case, potentially causing the sidewall to become significantly hot. When a water heater is used over a relatively long period of time, scale can build up on the inner surface of the heat transfer tube. This reduces the heat exchange efficiency of the heat transfer tube, reducing the amount of heat transferred from the fins to the heat transfer tube and causing the fins to become hotter. In this case, the sidewall of the case is more likely to become hotter. Since high temperatures on the sidewall of the case can, for example, cause thermal damage to components attached to the case or reduce the heat exchange efficiency of the water heater, it is desirable to appropriately address this issue.

[0004] One possible solution to the above-mentioned problem is to set the outer ends of the fins and the side wall of the case in a non-contact state so that a gap is created between them. However, simply adopting such a configuration may result in a large amount of high-temperature combustion gas entering the gap, which may ultimately cause the sidewall of the case to become very hot. Also, if a large amount of combustion gas enters the gap and passes through it, the amount of heat recovered by the multiple fins will decrease, making it more likely that the heat exchange efficiency will decrease.

[0005] In contrast, in the hot water device described in Patent Document 2, a part of an auxiliary member (heat insulating member) is joined to the body pipe, and another part of this auxiliary member is an extension part that extends from the body pipe toward the multiple fins, and this extension part blocks at least a part of the area between the body pipe and the multiple fins. Therefore, the extension part prevents a large amount of combustion gas from entering the gaps between the multiple fins and the side wall part of the case, and it is possible to prevent the side wall part from becoming too hot to some extent. However, according to Patent Document 2, a portion of the extension of the auxiliary member is a contact portion that contacts the side wall portion of the case, and a gap through which combustion gas can enter is formed between this contact portion and the outer ends of the multiple fins. Therefore, the contact portion is heated by the combustion gas that has entered this gap, and as a result, the side wall portion of the case is also heated. As a result, there is still room for improvement in terms of appropriately and sufficiently preventing the side wall portion from becoming too hot. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2017-116203 [Patent Document 2] Japanese Patent Application Publication No. 2020-3108 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention was devised under the circumstances described above, and its objective is to provide a heat exchanger that can appropriately prevent the side wall of the case from becoming extremely hot due to the influence of heating gas such as combustion gas, and a hot water device equipped with the same. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following technical solutions.

[0009] A heat exchanger provided according to a first aspect of the present invention comprises: a case into which a heating gas is supplied; a heat transfer tube disposed within the case and having a plurality of fins joined thereto; a body pipe located within the case upstream of the fins in the heating gas flow direction and in contact with a side wall of the case; and an auxiliary member including a body pipe joint joined to the body pipe and an extension portion extending from the body pipe joint toward the fins, wherein the fins are disposed at a position spaced from the side wall, and the extension portion of the auxiliary member includes an entry portion that enters between the fins and the side wall, and a first abutment portion that is provided at the entry portion and abuts against outer ends of the fins, and a space portion is formed between the first abutment portion and the side wall portion into which the inflow of the heating gas is inhibited.

[0010] This configuration provides the following effects. First, although the fins are heated to a high temperature by the heating gas, they are not in direct contact with the sidewall of the case, and therefore there is no direct heat transfer from the fins to the sidewall. Furthermore, the extension of the auxiliary member has a first abutment portion that abuts the outer ends of the fins. The space formed between this first abutment portion and the sidewall of the case is an area where the inflow of heating gas is suppressed and serves as a heat insulating portion. Therefore, the transfer of heat from the fins to the sidewall via the first abutment portion of the auxiliary member is also suppressed. This makes it possible to appropriately prevent the sidewall of the case from becoming significantly hot due to the influence of the heating gas. Furthermore, because the first contact portion of the extension of the auxiliary member contacts the outer ends of the fins, the heating gas does not enter between the first contact portion and the fins, eliminating or reducing the amount of heating gas that travels downstream of the fins in the heating gas flow direction without acting on the fins, thereby preventing a decrease in heat exchange efficiency. Additionally, according to the present invention, by covering the body pipe with the body pipe joint of the auxiliary member, it is possible to protect the body pipe by preventing the body pipe from being directly exposed to the heating gas. Furthermore, if there is a risk of highly acidic condensed water being generated when heat is recovered from the heating gas, the auxiliary member can prevent this condensed water from directly adhering to the body pipe, thereby preventing the body pipe from becoming susceptible to corrosion by the condensed water.

[0011] In the present invention, preferably, the extension portion of the auxiliary member further includes a bent portion that bends from a portion spaced away from the side wall portion of the case toward the side wall portion, and a portion of which forms a second abutment portion that abuts against the side wall portion.

[0012] With this configuration, a part of the extension part of the auxiliary member is bent and abuts against the side wall of the case as the second abutment part, which makes it possible to stabilize the attachment state of the auxiliary member. The bent part of the auxiliary member blocks a part of the space formed between the first abutment part of the auxiliary member and the side wall of the case, which is more preferable in terms of suppressing the entry and passage of heating gas into the space.

[0013] In the present invention, preferably, the heat transfer tube comprises a plurality of tubular sections arranged at intervals in a direction intersecting the flow direction of the heating gas, and among these plurality of tubular sections, the tubular section arranged closest to the body pipe is a specific tubular section, and the first abutment section of the auxiliary member includes in its target abutment area an area of ​​the outer ends of the plurality of fins that is downstream in the flow direction of the heating gas from the center of the specific tubular section.

[0014] This configuration provides the following effects. That is, the effect of suppressing excessive heat transfer from the multiple fins to the sidewall of the case via the second contact portion of the auxiliary member is obtained. That is, the temperature distribution around the specific tubular portion of the multiple fins is such that the downstream portion in the heating gas flow direction is lower in temperature than the upstream portion. Therefore, with this configuration, the first contact portion of the auxiliary member contacts the relatively low-temperature portions of the multiple fins, making it possible to lower the temperature of the second contact portion that contacts the sidewall of the case. Therefore, it is possible to more reliably prevent the sidewall from becoming too hot.

[0015] In the present invention, preferably, the case further comprises a plastic exhaust duct attached to the side wall portion at a position downstream of the auxiliary member in the direction of flow of the heating gas, and for discharging the heating gas from inside the case to the outside as exhaust gas after heat recovery by the plurality of fins and the heat transfer tube.

[0016] This configuration prevents the attachment point of the plastic exhaust duct from becoming extremely hot due to the heat transferred from the multiple fins, and makes it possible to appropriately avoid thermal damage to the exhaust duct. Using a plastic exhaust duct can reduce weight and manufacturing costs compared to using a metal exhaust duct.

[0017] A water heating device provided by a second aspect of the present invention is characterized by comprising the heat exchanger provided by the first aspect of the present invention and a burner that supplies combustion gas as the heating gas into the case of the heat exchanger.

[0018] According to this configuration, the same effects as those described for the heat exchanger provided by the first aspect of the present invention can be obtained.

[0019] Other features and advantages of the present invention will become more apparent from the following description of the preferred embodiments of the invention, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a perspective view showing an example of a heat exchanger according to the present invention. [Figure 2] 2 is a cross-sectional view of a main part showing an example of a hot water device in which the heat exchanger shown in FIG. 1 and a burner are combined, and the heat exchanger portion corresponds to the cross-sectional view taken along II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view of a main part taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 2. [Figure 5] FIG. 5 is an enlarged view of part V in FIG. 4. [Figure 6] 6 is a cross-sectional view taken along the line VI-VI in FIG. 5. [Figure 7] 10(a) and 10(b) are cross-sectional views of the main part showing another example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0022] The water heating device WH shown in FIG. 2 includes a heat exchanger HE and a burner 1, part of which is shown in phantom. It is equipped with:

[0023] As the burner 1, a conventionally known burner such as those described in Patent Documents 1 and 2 is used. In this burner 1, fuel gas is mixed with combustion air discharged from a fan (not shown), and this mixture is injected into the case 2 of the heat exchanger HE through a gas-permeable mixture injection member 10 provided at the upper opening of the case 2. The mixture is ignited, and combustion gas is supplied downward into the case 2 as heating gas. Sensible heat and latent heat are recovered from the combustion gas by the primary and secondary heat exchange sections H1 and H2 described below, thereby heating the hot water supplied to the primary and secondary heat exchange sections H1 and H2, and the hot water produced by this heating is supplied to the desired hot water supply destination.

[0024] 1 to 4, the heat exchanger HE includes, in addition to the case 2 described above, a plurality of body pipes 5, auxiliary members 8 (8a, 8b), a heat transfer tube 3 constituting the primary heat exchange section H1 and a plurality of plate-shaped fins 4 joined to the heat transfer tube 3, a plurality of heat transfer tubes 6 constituting the secondary heat exchange section H2, and an exhaust duct 29. Of the above-mentioned parts of the heat exchanger HE, the exhaust duct 29 is made of resin, while the rest is made of, for example, stainless steel. The heat transfer tube 3 corresponds to the "heat transfer tube to which a plurality of fins are joined" as defined in the present invention, but the heat transfer tube 6 does not.

[0025] The case 2 is a generally rectangular tubular shape having a bottom wall 28, and as shown in Fig. 3, is configured by combining a case main body 20 and a case auxiliary plate 21. The case main body 20 has a plurality of side walls 22a to 22c that are connected in a generally U-shaped cross section in a plan view, and has an opening 24 formed in one side surface. The case auxiliary plate 21 abuts against and is joined to a flange 25 provided on the case main body 20, and has a side wall 22d that closes the opening 24 in one side surface of the case main body 20.

[0026] 1 and 2, the heat transfer tube 3 is configured such that a plurality of straight tube sections 30 are arranged in two upper and lower rows at intervals in the width direction (horizontal direction) of the case 2, and the ends of these plurality of tube sections 30 are connected to each other via a substantially U-shaped bend pipe 36 outside the case 2. In the heat exchanger HE of this embodiment, hot water supplied from the water inlet 70a into the secondary heat exchange section H2 passes through the secondary heat exchange section H2 and is heated, and then supplied to the water inlet 59 of the body pipe 5. The hot water that has passed through the body pipe 5 is then sent to the heat transfer tubes 3 of the primary heat exchange section H1, where it is heated, and then discharged from the hot water outlet 39. The fins 4 are for absorbing heat and are arranged at appropriate intervals in the axial direction of the tubular portion 30, and the tubular portion 30 penetrates and is joined to the fins 4. Each fin 4 has a plurality of notched recesses 47 appropriately formed therein to uniformly distribute the temperature.

[0027] Each heat transfer tube 6 is a serpentine heat transfer tube, and as shown in Fig. 2, it has a serpentine shape in which a plurality of straight tube sections 60 extending horizontally and arranged at intervals in the vertical direction are connected in series via a plurality of connecting tube sections 61 that are semicircular in side view. The plurality of heat transfer tubes 6 are arranged at appropriate intervals in the width direction of the case 2 and are arranged in a staggered pattern with a difference in height between adjacent heat transfer tubes 6. In Fig. 2, two heat transfer tubes 6 are shown overlapping each other, making it difficult to distinguish between them, so one of them is shown with a dotted pattern. Both longitudinal ends of each heat transfer tube 6 are connected to headers 7a, 7b for inlet and outlet, which are provided on the outer surface of the side wall 22d. Hot water is supplied from the outside to the water inlet 70a of the header 7a, and the hot water, heated as it passes through the multiple heat transfer tubes 6, is discharged from the water outlet 70b of the header 7b and sent to the water inlet 59 of the body pipe 5 described above.

[0028] The exhaust duct 29 is a duct for exhausting the combustion gas after passing through the primary heat exchange section H1 and the secondary heat exchange section H2. This exhaust duct 29 is a member for discharging the exhaust gas outside the case 2 as exhaust gas and guiding it to a desired location. As shown in Fig. 4, this exhaust duct 29 is attached to the side wall 22a of the case 2 in an arrangement surrounding an exhaust port 29a provided in the side wall 22a. A partition wall 75 is provided within the case 2 to divide the secondary heat exchange section H2 into first and second areas Sa and Sb in the width direction of the case 2, and the upper part of this partition wall 75 is arranged so as to block the upper side of the second area Sb and is joined to the side wall 22a of the case 2. The combustion gas that has passed through the primary heat exchange section H1 travels downward through the first area Sa and, when it reaches the bottom of the case 2, is guided upward by the bottom wall 28 to enter the second area Sb and reach the exhaust port 29a and exhaust duct 29.

[0029] The body pipe 5 is used to heat hot and cold water, and is a member that cools the multiple side wall sections 22a to 22c of the case 2 to prevent thermal damage. This body pipe 5 is configured with multiple straight tubular sections 50a to 50c connected in a roughly U-shape when viewed from above. Note that the side wall section 22d of the case 2 is cooled by hot and cold water in the header section 35, which will be described later, so cooling by the body pipe 5 is omitted.

[0030] The multiple body pipes 5 are provided in multiple vertical stages in an area above the multiple fins 4 and heat transfer tubes 3, and are brazed to the inner surfaces of the side wall portions 22a to 22c of the case 2 in contact with them. The case auxiliary plate 21 is provided with multiple header sections 35 (35a, 35b) for circulating hot and cold water to the multiple body pipes 5. As shown in a partial cross section in Figure 3, each header section 35 has a cover member 351 joined to a base member 350 joined to the outer surface of the side wall 22d, with a chamber 352 formed inside these. Both ends of the multiple body pipes 5 (the outer ends of the straight tubular body sections 50a, 50b) penetrate the side wall 22d and are in communication with the chamber 352, are provided with a water inlet 59, or are connected to the heat transfer tube 3 via a bent pipe 32.

[0031] The hot and cold water paths through the multiple body pipes 5 are as follows. That is, hot water supplied to the water inlet 59 at one end of the topmost body pipe 5a passes through this body pipe 5a and flows into the upper header section 35a. After that, it flows into and passes through the second body pipe 5b, then flows into the lower header section 35b, and then into the third body pipe 5c. Having passed through this body pipe 5c, the hot water flows into the heat transfer tubes 3 via the bend pipe 32 and then reaches the tap port 39. In the process described above, the hot water is heated by the combustion gas.

[0032] The auxiliary members 8 (8a, 8b) are members that suppress temperature increases in the side wall portions 22a, 22b of the case 2 and improve heat exchange efficiency, and the auxiliary member 8a in particular is useful for suppressing high temperatures at the attachment point of the resin exhaust duct 29. These auxiliary members 8 are joined to the straight tubular portions 50a, 50b of the lowest body pipe 5 (5c) among the multiple body pipes 5. As shown in FIG. 3, the auxiliary members 8a, 8b extend in the longitudinal direction of the straight tubular portions 50a, 50b.

[0033] As shown in FIG. 5, the auxiliary member 8a includes a body pipe joint portion 80 and an extension portion 81. The body pipe joint 80 is arc-shaped in side view and fits onto the inner peripheral side surface (the central surface inside the case 2) of the straight tubular body portion 50a of the body pipe 5 so as to cover this inner peripheral side surface, and is joined to the straight tubular body portion 50a using means such as brazing.

[0034] The extension portion 81 of the auxiliary member 8a is a portion that extends from the body pipe joint portion 80 toward the fins 4, and includes an entry portion 81a that enters between the fins 4 and the side wall portion 22a of the case 2. The entry portion 81a includes a first contact portion C1, a portion beyond the first contact portion C1, and a portion beyond the first contact portion C1. It includes a bent portion 82 connected to the end side, and a second abutment portion C2 as a part of this bent portion 82.

[0035] The outer ends 40 of the fins 4 are spaced apart from the side wall 22a in the width direction of the case 2 and are not in direct contact with the side wall 22a. In contrast, the first contact portion C1 of the auxiliary member 8a contacts the outer surfaces of the outer ends 40 of the fins 4 in regions near the upper portions. More specifically, as shown in Fig. 6, a bent piece portion 41 bent in the thickness direction of each fin 4 is connected to the outer end portion 40 of each fin 4, and the first contact portion C1 is in surface contact with the outer surface of this bent piece portion 41. A space 9 is formed between the first contact portion C1 and the side wall portion 22a of the case 2. As shown in Fig. 5, this space 9 is a closed area surrounded by the auxiliary member 8a, the body pipe 5, and the side wall portion 22a, and is an area where the inflow of combustion gas is suppressed.

[0036] The first contact portion C1 contacts the outer ends 40 of the fins 4 over a range of an appropriate dimension La downward from the topmost position thereof, and the lower tip of this first contact portion C1 and the bent portion 82 are located an appropriate dimension Lb below the center O of the tubular portion 30a of the heat transfer tube 3 (the first contact portion C1 includes in its target contact area the region of the outer ends 40 of the fins 4 that is downstream of the center O of the tubular portion 30a in the direction of combustion gas flow). Note that, of the multiple tubular portions 30 of the heat transfer tube 3, the tubular portion 30a is the one that is positioned closest to the straight tubular portion 50a of the body pipe 5, and corresponds to a specific example of a "specific tubular portion" as defined in the present invention.

[0037] The bent portion 82 of the auxiliary member 8a is a portion bent from the tip of the first contact portion C1 toward the side wall portion 22a, and the tip of this bent portion 82 is the second contact portion C2 that contacts the side wall portion 22a. Preferably, this second contact portion C2 is brazed to the side wall portion 22a. This makes it possible to attach the auxiliary member 8a to the side wall portion 22a and the body pipe 5 reliably and firmly. The exhaust duct 29 is attached to the side wall portion 22a at a position below the second contact portion C2.

[0038] The extension portion 81 of the auxiliary member 8a is preferably elastically deformable to an appropriate degree in the width direction of the case 2, and when the fins 4 are heated by combustion gas and attempt to thermally expand, for example, in the direction of arrow Na in FIG. 5, the extension portion 81 deforms in the same direction, allowing the thermal expansion of the fins 4. This prevents large stresses and distortions from occurring in the fins 4, and in turn in the heat transfer tubes 3. The presence of the space 9 helps to cause the extension portion 81 to undergo the aforementioned elastic deformation.

[0039] The other auxiliary member 8b is joined to the straight tubular portion 50b. This auxiliary member 8b is bilaterally symmetrical to the above-mentioned auxiliary member 8a, and a detailed description thereof will be omitted.

[0040] Next, the operation of the heat exchanger HE and the water heating device WH equipped with the same will be described.

[0041] The fins 4 are heated to a high temperature by the combustion gas, but the fins 4 are not in direct contact with the side wall 22a of the case 2, and there is no direct heat transfer from the fins 4 to the side wall 22a. The first abutment portion C1 of the auxiliary member 8a abuts the outer end portion 40 of the fins 4, but a space 9 with a heat insulating function is formed between this first abutment portion C1 and the side wall 22a of the case 2, and therefore there is no direct heat transfer from the fins 4 to the side wall 22a via the first abutment portion C1.

[0042] Heat transferred from the multiple fins 4 to the auxiliary member 8a via the first contact portion C1 may be transferred to the side wall portion 22a of the case 2 via the second contact portion C2. However, the second contact portion C2 is the tip of the bent portion 82, and the contact area (heat transfer area) with the side wall portion 22a is small. Therefore, it is possible to reduce the amount of heat transferred from the second contact portion C2 to the side wall portion 22a.

[0043] As described above, the first contact portion C1 includes in its target contact area the region downstream of the center O of the tubular portion 30a (30) of the heat transfer tube 3 in the combustion gas flow direction, but the temperature distribution of the multiple fins 4 tends to be higher in the upper region, which is more upstream in the combustion gas flow direction, and lower in the lower region. Around the periphery of the tubular portion 30a, the temperature is lower below the center O than above. Because the first contact portion C1 is in contact with such a lower-temperature portion, the second contact portion C2, which is in contact with the side wall portion 22a of the case 2, is prevented from becoming as hot as the upper region of the multiple fins 4.

[0044] For this reason, the regions of side wall 22a of case 2 that are on the sides of fins 4 and the region below them are appropriately prevented from becoming significantly hot due to the heat from fins 4. Although exhaust duct 29 is made of resin, the temperature at the attachment point of exhaust duct 29 is also prevented from becoming too high, so exhaust duct 29 is appropriately prevented from being thermally damaged.

[0045] The extension portion 81 of the auxiliary member 8a includes a first contact portion C1 that contacts the outer ends 40 of the fins 4, making it possible to prevent combustion gas from entering between this first contact portion C1 and the outer ends 40 of the fins 4. Unlike this embodiment, if the auxiliary member 8a were configured not to include the first contact portion C1, much of the combustion gas would enter the area between the outer ends 40 of the fins 4 and the extension portion 81 of the auxiliary member 8a, resulting in wasted gas passing downward. In contrast, this embodiment makes it possible to eliminate such wasted gas and improve heat exchange efficiency.

[0046] The body pipe joint 80 of the auxiliary member 8a covers the straight tubular portion 50a of the body pipe 5, thereby protecting the straight tubular portion 50a from direct exposure to the heating gas. Furthermore, when heat is recovered from the combustion gas, highly acidic condensed water is generated, but the auxiliary member 8a also prevents this condensed water from directly adhering to the straight tubular portion 50a. This also prevents the straight tubular portion 50a from becoming susceptible to corrosion due to condensed water.

[0047] Although no exhaust duct 29 is provided on side wall 22b of case 2, auxiliary member 8b is provided corresponding to side wall 22b. This auxiliary member 8b provides the same effect as that obtained by auxiliary member 8a, and prevents side wall 22b from becoming too hot.

[0048] 7 shows another embodiment of the present invention. In this figure, elements that are the same as or similar to those in the previous embodiment are given the same reference numerals as in the previous embodiment, and redundant explanations will be omitted.

[0049] 7(a), of the extension portion 81 of the auxiliary member 8A, the entry portion 81a that enters between the outer ends 40 of the multiple fins 4 and the side wall portion 22a of the case 2 has a facing portion 84 that faces the outer ends 40 across a gap 98, and a first abutment portion C1 and a bent portion 82 are provided below this facing portion 84. A region 81b near the base of the extension portion 81 of the auxiliary member 8A blocks the region between the body pipe 5 and the multiple fins 4, and combustion gas is prevented from entering the gap 98 from the center side of the case 2.

[0050] The region of the outer end 40 of the plurality of fins 4 that is in contact with the first contact portion C1 is a narrow area located below the center O of the tubular portion 30a. This prevents the auxiliary member 8A from becoming too hot due to heat transfer from the plurality of fins 4 to the auxiliary member 8A. are. A gap 9' is formed between the facing portion 84 of the auxiliary member 8A and the side wall portion 22a of the case 2, located above the space 9 and communicating with the space 9. This gap 9' provides thermal insulation, similar to the space 9. The gap 9' is formed, for example, by a small protruding stepped portion 83 provided on the facing portion 84 of the auxiliary member 8A abutting against the side wall portion 22a. The stepped portion 83 may also be provided on the side wall portion 22a rather than the auxiliary member 8A. Using such a stepped portion 83 as a means for forming the gap 9' reduces the contact area between the auxiliary member 8A and the side wall portion 22a, thereby reducing the amount of heat transfer from the auxiliary member 8A to the side wall portion 22a and enabling proper dimensional control of the gap 9'. According to this embodiment, similarly to the above-described embodiment, it is possible to prevent the temperature of the side wall portion 22a from rising too high.

[0051] 7(b), auxiliary member 8B of the embodiment shown in FIG. 7(b) differs from auxiliary member 8A shown in FIG. 7(a) in the position and shape of the first contact portion C1. More specifically, inclined portions 44 that decrease in height toward the center in the width direction of case 2 are formed on outer end portions 40 of the multiple fins 4. In auxiliary member 8A, first contact portion C1 does not contact inclined portion 44 but contacts an area above it, whereas in auxiliary member 8B, first contact portion C1 is positioned and shaped to contact inclined portion 44. In this embodiment, the same effect as in the embodiment shown in FIG. 7(a) can be obtained.

[0052] The present invention is not limited to the above-described embodiment, and the specific configurations of the heat exchanger and the hot water device according to the present invention can be freely designed and modified in various ways within the intended scope of the present invention.

[0053] As for the auxiliary member, at least one auxiliary member is sufficient, and it is not necessary to provide multiple auxiliary members. For example, in order to prevent thermal damage to the exhaust duct, it is possible to provide only one auxiliary member in the area corresponding to the exhaust duct.

[0054] There are no specific limitations on the shapes, sizes, materials, etc. of the auxiliary member, case, body pipe, fins, and heat transfer tubes. The body pipe may be, for example, a spiral pipe that is generally rectangular in plan view. In the above-described embodiment, the exhaust duct is attached to the side wall of the case, but it is also possible to adopt a configuration in which, for example, the case has an opening at the bottom and the exhaust duct is connected to this opening at the bottom. The heat exchanger according to the present invention may be configured without the secondary heat exchange section for recovering latent heat.

[0055] The hot water device in the above-described embodiment is a reverse combustion type in which the burner is arranged above the heat exchanger, but is not limited to this and can also be a forward combustion type in which the burner is arranged below the heat exchanger, for example. The heating gas is not limited to combustion gas, but may be, for example, high-temperature exhaust gas generated in a cogeneration system. The hot water device referred to in this invention is a device that has the function of heating hot water to produce hot water, and includes not only general hot water supply devices, but also, for example, bath hot water supply devices, heating hot water supply devices, and snow melting hot water supply devices. [Explanation of symbols]

[0056] C1 First contact portion (of auxiliary member) C2 Second contact part (of auxiliary member) WH water heating device HE heat exchanger 1 burner 2 cases 22a, 22b side wall part 29 Exhaust duct 3 heat transfer tubes 4 fins 40 outer end (of fin) 5-body pipe 50a~50c Straight pipe section (body pipe) 8 (8a, 8b) Auxiliary member 8A, 8B Auxiliary parts 80 Body pipe joint (auxiliary part) 81 Extension part (of auxiliary member) 81a Entry section (of auxiliary member) 82 Bent part (of auxiliary member) 9 Space section

Claims

1. a case into which heating gas is supplied; a heat transfer tube disposed within the case and having a plurality of fins joined thereto; a shell pipe located inside the case on the upstream side of the fins in the heating gas flow direction and in contact with a side wall portion of the case; an auxiliary member including a body pipe joint portion joined to the body pipe and an extension portion extending from the body pipe joint portion toward the plurality of fins; A heat exchanger comprising: the plurality of fins are provided at positions spaced apart from the side wall portion, the extension portion of the auxiliary member includes an entry portion that enters between the plurality of fins and the side wall portion, and a first abutment portion that is provided in the entry portion and abuts against outer ends of the plurality of fins, a space portion into which the inflow of the heating gas is restricted is formed between the first contact portion and the side wall portion;

2. 2. The heat exchanger of claim 1, A heat exchanger, wherein the extension portion of the auxiliary member further includes a bent portion that bends from a portion spaced away from the side wall portion of the case toward the side wall portion, and has a second abutment portion that abuts against the side wall portion.

3. 3. The heat exchanger according to claim 2, the heat transfer tube includes a plurality of pipe sections arranged at intervals in a direction intersecting a flow direction of the heating gas, and among the plurality of pipe sections, the pipe section arranged closest to the body pipe is a specific pipe section; A heat exchanger in which the first abutment portion of the auxiliary member includes, in its target abutment area, an area of ​​the outer ends of the plurality of fins that is downstream in the heating gas flow direction from the center of the specific tubular portion.

4. 4. The heat exchanger according to claim 1, The heat exchanger further comprises a resin exhaust duct attached to the side wall portion of the case at a position downstream of the auxiliary member in the heating gas flow direction, and for discharging the heating gas from inside the case to the outside as exhaust gas after heat recovery by the plurality of fins and the heat transfer tube.

5. A heat exchanger according to any one of claims 1 to 4; a burner that supplies combustion gas as the heating gas into the case of the heat exchanger; A water heating device comprising:

Images