COMBUSTION DEVICE

Description

FIELD OF THE INVENTION

The present invention relates to a combustion device having an outer casing and a combustion device main body housed in the outer casing. Especially, the present invention relates to an improvement of an exhaust port member to prevent drain from scattering to an outside.

DESCRIPTION OF THE RELATED ART

In a gas combustion device, combustion exhaust gas is generated by combustion of a burner, and a sensible heat exchanger and a latent heat exchanger accommodated in a combustion box are heated by the combustion exhaust gas. Then, sensible heat in the combustion exhaust gas is absorbed by the sensible heat exchanger and latent heat in the combustion exhaust gas after the sensible heat is absorbed is absorbed by the latent heat exchanger. At this time, acid drain is generated by cooling water vapor in the combustion exhaust gas below a dew point and condensing the water vapor. Thus, the drain generated in the combustion box flows along with flow of the combustion exhaust gas, and scatters to an outside through a front end opening of an exhaust port member as an exhaust port.

In order to prevent the drain from scattering from the exhaust port member to the outside through the front end opening, it is proposed to provide a standing wall standing on a lower surface portion in the exhaust port member (for example, Patent Prior Art 1). According to this exhaust port member, the flow of the combustion exhaust gas is blocked by the standing wall, and therefore, the drain accumulates in a vicinity of the standing wall.

Unlike an upward combustion type combustion device described in the Patent Prior Art 1, there is a downward combustion type combustion device. The downward combustion type combustion device has: a burner which ejects a mixture gas downward for combustion to generate the combustion exhaust gas; a combustion box which accommodates therein a heat exchanger heated by the combustion exhaust gas and which is disposed below the burner; and an exhaust duct which is connected to an outlet port of the combustion box and which extends upward from the outlet port. According to the combustion device described above, as the combustion exhaust gas is cooled to the dew point or less not only in the combustion box but also in the exhaust duct, a large amount of drain is generated and flows into the exhaust port member. As a result, there is a problem that it is not possible to prevent scattering of the drain to the outside only by providing a drain accumulation location at an inside lower portion of the exhaust port member.

Further, in general, a temperature of the combustion exhaust gas discharged from the exhaust port member to the outside is higher than a temperature of the exhaust port member. For this reason, the drain is generated when the combustion exhaust gas contacts a peripheral edge of the front end opening of the exhaust port member, and scatters to the outside. Especially, in a combustion device connected to a storage tank, in a case where a temperature of hot water supplied from the storage tank to a latent heat exchanger is high, the combustion exhaust gas, latent heat of which is not sufficiently recovered, flows into the exhaust duct from the combustion box. When such combustion exhaust gas contacts an inner wall surface of the exhaust port member, a large amount of drain is generated inside the exhaust port member, and the drain easily scatters to the outside.

PRIOR ARTS

• [Patent Document 1] Japanese Unexamined Patent Publication No. JP2022-012812 A.

SUMMARY OF THE INVENTION

The present invention has been made to solve the problem described above, and an object of the present invention is to prevent drain from scattering from an exhaust port member to an outside through a front end opening thereof.

According to one aspect of the present invention, there is provided a combustion device comprising:

• • an outer casing; and
  • a combustion device main body housed in the outer casing, wherein
  • the outer casing has a casing body having a front opening which opens frontward, and a front cover closing the front opening of the casing body and having an exhaust port member insertion hole,
  • the combustion device main body has a burner which ejects mixture gas downward for combustion to generate combustion exhaust gas, a combustion box accommodating therein a heat exchanger heated by the combustion exhaust gas and disposed below the burner, an exhaust duct connected to an outlet port of the combustion box such that the combustion exhaust gas flows therein, and an exhaust port member connected to a downstream end of the exhaust duct to discharge the combustion exhaust gas to an outside,
  • the exhaust duct includes a riser duct section extending from the outlet port of the combustion box to a predetermined position above the burner through behind the combustion device main body, and a horizontal duct section bent from an upper end of the riser duct section, extending toward the front cover, and connected to the exhaust port member,
  • the exhaust port member has an upper wall portion and a lower wall portion separated from each other in an up-down direction, a left wall portion, and a right wall portion such that an exhaust passage is formed inside the exhaust port member,
  • the exhaust port member has an elongated front end opening flat in a left-right direction and an elongated back end opening flat in the left-right direction,
  • the upper wall portion and the lower wall portion of the exhaust port member protrude frontward from an inside of the outer casing through the exhaust port member insertion hole of the front cover,
  • the lower wall portion of the exhaust port member is inclined upward toward the front end opening,
  • an upper inner wall surface of the upper wall portion of the exhaust port member has a first upper inner wall surface portion extending from the front end opening to a predetermined position which is located backward of the front end opening, an upper protruding wall surface portion protruding inward of the exhaust passage from a back end of the first upper inner wall surface portion over the entire exhaust passage in the left-right direction, and a second upper inner wall surface portion extending from an inner end of the upper protruding wall surface portion toward the back end opening,
  • the exhaust passage which is located forward of the upper protruding wall surface portion expands upwardly as compared with the exhaust passage which is located backward of the upper protruding wall surface portion,
  • the second upper inner wall surface portion is inclined upward toward the front end opening, and
  • in a cross section in a front-back direction, an inclination angle of the second upper inner wall surface portion with respect to a horizontal plane is smaller than an inclination angle of a virtual line connecting the inner end of the upper protruding wall surface portion and a front end of the first upper inner wall surface portion forming the front end opening with respect to the horizontal plane.

According to the present invention, it is possible to prevent the drain from scattering from the exhaust port member to the outside through the front end opening thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view illustrating one example of a combustion device according to an embodiment of the present invention;

FIG. 2 is a schematic partial longitudinal sectional view illustrating one example of the combustion device according to the embodiment of the present invention;

FIG. 3 is a schematic perspective view illustrating one example of the combustion device main body according to the embodiment of the present invention; and

FIG. 4 is a schematic enlarged partial sectional view illustrating one example of the combustion device according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter, referring to drawings, a combustion device according to an embodiment of the present invention will be described. As illustrated in FIGS. 1 and 2, the combustion device according to the present embodiment has an outer casing 100 and a combustion device main body 1 housed in the outer casing 100.

The outer casing 100 has a rectangular box-shaped casing body 101 having a front opening 103 opening frontward and a front cover 102 closing the front opening 103. Note that in the present specification, a side on which the front cover 102 is provided is referred to as a front side, and when viewed from the front side, a depth direction of the outer casing 100 is referred to as a front-back direction, a width direction of the outer casing 100 is referred to as a left-right direction, and a height direction of the outer casing 100 is referred to as an up-down direction. An exhaust port member insertion hole 104 flat in the left-right direction opens at an upper center portion of the front cover 102 in the left-right direction. An exhaust port member 5 described later is inserted into the exhaust port member insertion hole 104. A rainproof plate 105 standing from a lower end of the front cover 102 to a predetermined height is attached onto a back surface of the front cover 102. Each of the casing body 101 and the front cover 102 is formed by molding a sheet metal into a predetermined shape.

As illustrated in FIGS. 2 and 3, the combustion device main body 1 comprises: a burner 2 which ejects a mixture gas of fuel gas and air downward for combustion to generate combustion exhaust gas; a combustion box 3 which is disposed on a lower side of the burner 2 so as to surround a combustion space for the burner 2; an exhaust duct 4 in which the combustion exhaust gas discharged from the combustion box 3 flows; and the exhaust port member 5 connected to a downstream end of the exhaust duct 4 to discharge the combustion exhaust gas to an outside.

The burner 2 is provided with: a box-shaped burner body 21 which opens downward; and a combustion plate 22 which covers a downward opening surface of the burner body 21. The burner body 21 has, on an upper portion thereof, an inlet port 23 which opens sideways. Thus, the mixture gas is supplied from a fan (not illustrated) through the inlet port 23 into the burner body 21. Then, the mixture gas is ejected downward from a mixture gas ejection portion 24 disposed in the combustion plate 22, thereby performing totally primary air combustion. Note that the combustion plate 22 has a large opening in a central portion thereof. Textile fabric 24a of heat-resistant fibers is mounted into this opening, and a distribution plate 24b having a multiplicity of distribution holes is overlapped with the textile fabric 24a. In this manner, the mixture gas ejection portion 24 is constituted by the textile fabric 24a and the distribution plate 24b.

The combustion box 3 is constituted by: an upper box 31 which is open on both upper and lower surfaces and which is fastened, at an upper end portion thereof, to a periphery of a lower surface of the burner body 21; a flat and dish-like intermediate box 32 which is fastened to a lower end of the upper box 31; and a lower box 33 which is blocked at both upper and lower surfaces and which has an upper plate portion 33a to be fastened to a bottom plate portion 32a of the intermediate box 32. A front portion of the bottom plate portion 32a of the intermediate box 32 and a front portion of the upper plate portion 33a of the lower box 33 are provided with a vent hole 34 which brings into communication an inside space of the intermediate box 32 and an inside space of the lower box 33. Further, a back surface of the lower box 33 of the combustion box 3 is provided with an outlet port 35 through which the combustion exhaust gas flows out. It is thus so arranged that the combustion exhaust gas flows from the inside of the upper box 31 through the inside of the intermediate box 32, the vent hole 34, the inside of the lower box 33 and the outlet port 35 into the exhaust duct 4.

The heat exchanger 30 is constituted by: a main heat exchanger 301 (a sensible heat exchanger) of fin-and-tube type which is disposed in the upper box 31 and which is made up of a plurality of heat-absorbing fins 301a, and a plurality of heat-absorbing pipes 301b which penetrates through the heat-absorbing fins 301a; and a subsidiary heat exchanger 302 (a latent heat exchanger) which is disposed in the lower box 33 and which is made up of a plurality of upper and lower heat-absorbing pipes 302b elongated in a meandering manner in the left-right direction. On outside surfaces of side plate portions 31a facing each other on one lateral side and on another lateral side of the upper box 31, there are provided a plurality of connection headers 301c which defines connection passages of the adjoining two heat-absorbing pipes 301b, 301b. All the heat-absorbing pipes 301b are thus arranged to be connected in series. Further, a connection port 301d is provided in one connection header 301c which defines the connection passage connected to the heat-absorbing pipe 301b on an upstream end of a water passage.

Further, on an outside surface of a side plate portion 33b on one lateral side of the lower box 33, there is provided: an inlet-side header 303b which defines a connection passage connecting together one end portions of the plurality of upper and lower heat-absorbing pipes 302b of the subsidiary heat exchanger 302; and an outlet-side header 303c which defines a connection passage connecting together other end portions of the plurality of upper and lower heat-absorbing pipes 302b. The inlet-side header 303b is provided with a water inlet port 303d to which is connected a water supply passage supplied hot water from a storage tank (not illustrated), and the outlet-side header 303c is provided with a connection port 303e to which is connected the above-mentioned connection port 301d through a piping (not illustrated). It is thus so arranged that the hot water from the water inlet port 303d flows, via the subsidiary heat exchanger 302, to the main heat exchanger 301. Further, in an upper portion of the upper box 31 which is above the main heat exchanger 301, there is provided a water jacket 310 which is constituted by a plurality of upper and lower water pipes in which the hot water passing through the main heat exchanger 301 flows, to prevent the said portion from being overheated. A downstream end of the water jacket 310 is connected to a hot water supply passage which returns the hot water to the storage tank.

The exhaust duct 4 is made of resin. The exhaust duct 4 includes: a riser duct section 42 having a duct inlet port 41 at a lower front surface connected to the outlet port 35 and elongated in the up-down direction; and a horizontal duct section 43 bent from an upper end portion of the riser duct section 42, extending frontward, and formed flat in the left-right direction. The riser duct section 42 passes through a clearance between the combustion device main body 1 and a back surface of the casing body 101, and extends to a predetermined position above the burner 2.

As illustrated in FIGS. 2 to 4, a front end portion of the horizontal duct section 43, i.e., a downstream end of the exhaust duct 4, is connected to the exhaust port member 5. Therefore, the combustion exhaust gas which flows from the outlet port 35 of the combustion box 3 into the exhaust duct 4 is discharged from the exhaust port member 5 to the outside through the riser duct section 42 and the horizontal duct section 43. In a vicinity of the front end portion of the horizontal duct section 43, a flange portion 461 standing outward from an outer peripheral surface of the horizontal duct section 43 and upper and lower ribs 462 extending backward from upper and lower portions of the flange portion 461 are formed. A front surface of the flange portion 461 of the horizontal duct section 43 contacts a back surface of a flange portion 52 at a back end portion of the later-described exhaust port member 5 via an annular packing 200. Further, an upper claw portion 501 and a lower claw portion 502 extending backward from upper and lower back end portions of the exhaust port member 5 each engage with the upper and lower ribs 462. The horizontal duct section 43 has a duct tip end tubular portion 430 protruding frontward from the flange portion 461.

The duct tip end tubular portion 430 has, at a front end portion thereof, an inner tubular protruding portion 432 forming a duct outlet port 431 flat in the left-right direction, an outer tubular protruding portion 433 having an inner diameter greater than an outer diameter of the inner tubular protruding portion 432 and slightly protruding frontward with respect to the inner tubular protruding portion 432, and an annular duct engagement groove 434 formed between the inner tubular protruding portion 432 and the outer tubular protruding portion 433 and recessed backward. When the duct tip end tubular portion 430 fits into the back end portion of the later-described exhaust port member 5, a front end of the outer tubular protruding portion 433 engages with an engagement groove 553 in the exhaust port member 5. Further, a back end of a tubular protruding portion 60 protruding backward in the later-described exhaust port member 5 engages with the duct engagement groove 434 between the inner tubular protruding portion 432 and the outer tubular protruding portion 433. Further, a duct lower inner wall surface 435a of a duct lower wall portion 435 at the front end portion of the duct tip end tubular portion 430 forming the duct outlet port 431 is inclined upward toward the duct outlet port 431 at an inclination angle Ad (for example, about 3 to about 4 degrees) with respect to a horizontal plane. Note that in FIG. 4, a dash line indicating each inclination angle indicates a horizontal line.

The exhaust port member 5 is made of resin. The exhaust port member 5 has: a tip end tubular portion 51 positioned at a front end portion and formed flat in the left-right direction; the flange portion 52 standing outward from an outer peripheral surface at a back end of the tip end tubular portion 51; a rain receiving portion 53 extending backward from an outer end of the flange portion 52; a bank portion 54 standing from a back edge of the rain receiving portion 53; and the upper and lower claw portions 501 and 502 extending backward from a back surface of the bank portion 54.

The tip end tubular portion 51 has: an upper wall portion 55 and a lower wall portion 56 which are flat plates facing each other with a certain space in the up-down direction; a left wall portion 57 connecting left ends of the upper and lower wall portions 55 and 56 to each other and having a semicircular cross section in the left-right direction; and a right wall portion 58 connecting right ends of the upper and lower wall portions 55 and 56 to each other and having a semicircular cross section in the left-right direction. The tip end tubular portion 51 is open frontward and backward. Front end portions of these peripheral wall portions 55 to 58 of the tip end tubular portion 51 protrude from an inside of the outer casing 100 to the outside through the exhaust port member insertion hole 104 of the front cover 102. Thus, an opening at a front end of the tip end tubular portion 51 forms a front end opening 71 which is an exhaust port flat in the left-right direction. Further, an opening at a back end of the tip end tubular portion 51 forms an insertion port 75 into which the duct tip end tubular portion 430 of the horizontal duct section 43 as described above is inserted. Further, the front end portion of the tip end tubular portion 51 forms a protruding portion 51a protruding frontward from the exhaust port member insertion hole 104 of the front cover 102.

The upper wall portion 55 has: a first upper wall portion 551 extending substantially horizontally backward from the front end of the tip end tubular portion 51 to the flange portion 52; and a second upper wall portion 552 protruding downward from a predetermined position of an upper inner wall surface 55a, which is located forward of a center portion of the tip end tubular portion 51 in the front-back direction and backward of the front end of the tip end tubular portion 51 of the first upper wall portion 551, bent backward at a lower end (inner end) E, and extending diagonally downward to the center portion of the tip end tubular portion 51 in the front-back direction.

The lower wall portion 56 has: a first lower wall portion 561 extending diagonally downward toward a back side from the front end of the tip end tubular portion 51 to a position facing a back end portion of the second upper wall portion 552 in the up-down direction; and a second lower wall portion 562 protruding downward from a predetermined position of a first outer lower wall surface 561b, which is located forward of a back end of the first lower wall portion 561 and backward of the front end of the tip end tubular portion 51, bent backward from a protruding end, and extending substantially horizontally to the flange portion 52. Although not illustrated, left and right back end portions of the second upper wall portion 552 and the first lower wall portion 561 are connected to each other via inner left and right wall portions provided inward of the left and right wall portions 57 and 58 and having semicircular cross sections in the left-right direction. Thus, the tubular protruding portion 60 having an opening flat in the left-right direction is formed at the center portion in the front-back direction in the tip end tubular portion 51. When the exhaust port member 5 and the exhaust duct 4 are connected to each other, the opening at the back end of the tubular protruding portion 60 in the tip end tubular portion 51 communicates with the duct outlet port 431 of the exhaust duct 4. Thus, the opening at the back end of the tubular protruding portion 60 in the tip end tubular portion 51 forms a back end opening 72 of the exhaust port member 5. Further, the first outer lower wall surface 561b of the first lower wall portion 561 and a second outer lower wall surface 562b of the second lower wall portion 562 in a region of the protruding portion 51a form a lower surface of the protruding portion 51a protruding frontward from the exhaust port member insertion hole 104 of the front cover 102.

The first lower wall portion 561 is formed with a plurality of (five in this embodiment) thin plate-shaped hanging portions 80 which extends downward from the first outer lower wall surface 561b between a front end of the first lower wall portion 561 forming the front end opening 71 and a front end of the second lower wall portion 562. The plurality of hanging portions 80 is provided at predetermined intervals in the front-back direction. Thus, a plurality of recessed grooves 82 recessed upward is formed between the hanging portions 80 adjacent to each other in the front-back direction and between the hanging portion 80 positioned at a back end and the second lower wall portion 562. Each hanging portion 80 is formed over the entire first lower wall portion 561 in the left-right direction. Further, a lower end of each hanging portion 80 extends to the substantially same position in the up-down direction as a lower end of the second outer lower wall surface 562b of the second lower wall portion 562 described above. Thus, although the recessed grooves 82 are formed at the lower surface of the exhaust port member 5, the protruding portion 51a of the exhaust port member 5 has an unified appearance. In addition, since the first lower wall portion 561 is inclined downward toward the back side, a depth of the recessed groove 82 from a lower opening end to the first outer lower wall surface 561b increases toward the front.

Front and back surfaces of the plurality of hanging portions 80 are formed of substantially vertically-standing surface portions, except for a back surface of the hanging portion 80 extending downward from the front end of the first lower wall portion 561 forming the front end opening 71. Further, the back surface of the hanging portion 80 positioned at the front end of the first lower wall portion 561 has: a backwardly-inclined surface portion inclined backward toward an upper side from the lower end at a predetermined inclination angle with respect to the horizontal plane; and a back standing surface portion extending substantially vertically upward from an upper end of the backwardly-inclined surface portion toward the first outer lower wall surface 561b. Thus, the lower end of the hanging portion 80 positioned at the front end has an acute V-shape in a cross section in the front-back direction.

The annular engagement groove 553 opening backward is formed between the tubular protruding portion 60 and the first upper wall portion 551, the second lower wall portion 562, and the left and right wall portions 57 and 58 surrounding the tubular protruding portion 60. In order to connect the exhaust port member 5 and the exhaust duct 4 to each other, when the duct tip end tubular portion 430 of the horizontal duct section 43 of the exhaust duct 4 is inserted into the exhaust port member 5 through the insertion port 75 at the back end portion of the exhaust port member 5, the outer tubular protruding portion 433 of the duct tip end tubular portion 430 of the horizontal duct section 43 described above engages with the engagement groove 553. Further, the back end of the tubular protruding portion 60 protruding backward engages with the duct engagement groove 434 between the outer tubular protruding portion 433 and the inner tubular protruding portion 432. When the exhaust port member 5 and the exhaust duct 4 are connected to each other, an exhaust passage Pa of the combustion exhaust gas communicating with an exhaust passage Pu of the exhaust duct 4 is formed inside the exhaust port member 5.

The upper inner wall surface 55a of the upper wall portion 55 of the exhaust port member 5 has a first upper inner wall surface portion 55b formed by the first upper wall portion 551, and an upper protruding wall surface portion 55c and a second upper inner wall surface portion 55d formed by the second upper inner wall portion 552 having an L-shaped cross section in the front-back direction. The first upper inner wall surface portion 55b extends from the front end opening 71 to a front end of the second upper wall portion 552. The upper protruding wall surface portion 55c extends downward from a back end of the first upper inner wall surface portion 55b. The second upper inner wall surface portion 55d extends from a lower end of the upper protruding wall surface portion 55c toward the back end opening 72. The first upper inner wall surface portion 55b extends substantially horizontally backward. Further, the upper protruding wall surface portion 55c hangs downward from the first upper inner wall surface portion 55b over the entire exhaust passage Pa in the left-right direction. Thus, a step portion raised downward is formed at the predetermined position of the upper inner wall surface 55a of the exhaust port member 5, which is located backward of the front end opening 71. Further, the exhaust passage Pa which is located forward of the upper protruding wall surface portion 55c in the exhaust port member 5 expands upwardly as compared with the exhaust passage Pa which is located backward of the upper protruding wall surface portion 55c.

The second upper inner wall surface portion 55d connected to the upper protruding wall surface portion 55c is inclined upward toward the front end opening 71 at an inclination angle Ai (for example, about 3 to about 4 degrees) with respect to the horizontal plane (a chain line of the inclination angle Ai indicates an extension of the second upper inner wall surface portion 55d). Further, in a cross section in the front-back direction, the first upper inner wall surface portion 55b, the upper protruding wall surface portion 55c, and the second upper inner wall surface portion 55d are formed such that the inclination angle Ai of the second upper inner wall surface portion 55d as described above is smaller than an inclination angle Aj of a virtual line Lj connecting the lower end (inner end) E of the upper protruding wall surface portion 55c and a front end of the first upper inner wall surface portion 55b forming the front end opening 71 with respect to the horizontal plane by a predetermined angle (for example, about 11 to about 12 degrees). Note that the inclination angles of the first upper inner wall surface portion 55b, the upper protruding wall surface portion 55c, and the second upper inner wall surface portion 55d and the lengths thereof in the front-back direction can be appropriately set as long as the inclination angle Ai of the second upper inner wall surface portion 55d is smaller than the inclination angle Aj of the virtual line Lj.

The first lower wall portion 561 of the exhaust port member 5 forming the front end opening 71 is inclined upward from the back end opening 72 toward the front end opening 71. A lower inner wall surface 56a of the first lower wall portion 561 is inclined upward from the back end opening 72 toward the front end opening 71 at an inclination angle As (for example, about 9 to about 11 degrees) with respect to the horizontal plane (a chain line of the inclination angle As indicates an extension of the lower inner wall surface 56a).

The second upper inner wall surface portion 55d of the upper wall portion 55 and the lower inner wall surface 56a of the lower wall portion 56 are preferably formed such that the inclination angle As of the lower inner wall surface 56a facing the second upper inner wall surface portion 55d in the up-down direction with respect to the horizontal plane is greater than the inclination angle Ai of the second upper inner wall surface portion 55d with respect to the horizontal plane. Further, the lower inner wall surface 56a of the first lower wall portion 561 is preferably formed such that the inclination angle As is smaller than the inclination angle Aj. Further, the lower inner wall surface 56a of the lower wall portion 56 forming the back end opening 72 and the duct lower inner wall surface 435a of the duct lower wall portion 435 forming the duct outlet port 431 of the exhaust duct 4 communicating with the back end opening 72 of the exhaust port member 5 are preferably formed such that the inclination angle As of the lower inner wall surface 56a is greater than the inclination angle Ad of the duct lower inner wall surface 435a.

According to the present embodiment, the tip end tubular portion 51 forming a downstream end of the exhaust port member 5 is formed with the upper protruding wall surface portion 55c protruding inward of the exhaust passage Pa from the predetermined position of the first upper inner wall surface portion 55b, which is located backward of the front end opening 71, and the second upper inner wall surface portion 55d extending backward from the lower end of the upper protruding wall surface portion 55c. Thus, the exhaust passage Pa in the exhaust port member 5 which is located forward of the upper protruding wall surface portion 55c expands upwardly as compared with the exhaust passage Pa in the exhaust port member 5 which is located backward of the upper protruding wall surface portion 55c. Accordingly, the combustion exhaust gas flowing into the exhaust port member 5 through the back end opening 72 and flowing along the second upper inner wall surface portion 55d is less likely to flow toward the first upper inner wall surface portion 55b at a peripheral edge of the front end opening 71 which is cooled most by ambient air. As a result, it is possible to reduce contact of the combustion exhaust gas with the first upper inner wall surface portion 55b at the peripheral edge of the front end opening 71. With this configuration, it is possible to reduce drain generated at the peripheral edge of the front end opening 71.

Further, according to the present embodiment, in the cross section in the front-back direction, the inclination angle Ai of the second upper inner wall surface portion 55d with respect to the horizontal plane is smaller than the inclination angle Aj of the virtual line connecting the lower end E of the upper protruding wall surface portion 55c and the front end of the first upper inner wall surface portion 55b forming the front end opening 71 to each other with respect to the horizontal plane. Thus, the combustion exhaust gas flowing forward from a front end portion of the second upper inner wall surface portion 55d is less likely to spread upward. Accordingly, it is possible to reliably prevent contact of the combustion exhaust gas with the first upper inner wall surface portion 55b at the peripheral edge of the front end opening 71. With this configuration, it is possible to reduce the drain generated at the peripheral edge of the front end opening 71. Note that in the present embodiment, the second upper inner wall surface portion 55d is formed at the single inclination angle. However, the second upper inner wall surface portion 55d may have a plurality of inclination angles. In this case, the first upper inner wall surface portion 55b, the upper protruding wall surface portion 55c, and the second upper inner wall surface portion 55d are formed such that the inclination angle of the front end portion of the second upper inner wall surface portion 55d connected to the lower end E of the upper protruding wall surface portion 55c with respect to the horizontal plane is smaller than the inclination angle of the virtual line with respect to the horizontal plane.

Further, according to the present embodiment, the lower inner wall surface 56a of the lower wall portion 56 is inclined upward toward the front end opening 71. Thus, even if the drain generated in the exhaust duct 4 flows into the exhaust port member 5 or the drain is generated in the exhaust port member 5, the drain can be returned to the exhaust duct 4.

As described above, according to the present embodiment, since the combustion exhaust gas is less likely to contact the peripheral edge of the front end opening 71 of the exhaust port member 5, it is possible to reduce the drain generated at the peripheral edge of the front end opening 71. Further, the drain flowing into the exhaust port member 5 from the exhaust duct 4 or the drain generated in the exhaust port member 5 can be returned to the exhaust duct 4. Accordingly, even when the downward combustion type combustion device having the long exhaust duct 4 is connected to the storage tank, high-temperature hot water is supplied from the storage tank to the subsidiary heat exchanger 302, and the combustion exhaust gas, latent heat of which is not sufficiently recovered by the subsidiary heat exchanger 302, flows into the exhaust duct 4, it is possible to reliably prevent the drain from scattering to the outside from the exhaust port member 5 through the front end opening 71 thereof.

Note that in the above-described embodiment, the first upper inner wall surface portion 55b, the upper protruding wall surface portion 55c, and the second upper inner wall surface portion 55d are formed at the upper inner wall surface 55a of the upper wall portion 55. However, wall surface portions corresponding to these wall surface portions may be provided at the lower inner wall surface 56a of the lower wall portion 56, or be provided at both inner wall surfaces 55a and 56a of the upper wall portion 55 and the lower wall portion 56. In a case where a first lower inner wall surface portion, a lower protruding wall surface portion, and a second lower inner wall surface portion corresponding to the configuration of the above-described embodiment are provided at the lower inner wall surface 56a of the lower wall portion 56, inclination angles of the first lower inner wall surface portion, the lower protruding wall surface portion, and the second lower inner wall surface portion and the lengths thereof in the front-back direction are appropriately designed such that the flow of the combustion exhaust gas, which flows along the second lower inner wall surface portion toward a front end of the first lower inner wall surface portion forming the front end opening 71, can be reduced and contact of the combustion exhaust gas with the first lower inner wall surface portion at the peripheral edge of the front end opening 71 can be reduced.

Further, according to the present embodiment, the hot water is supplied to the combustion device from the storage tank. However, circulating hot water to be heated or cold water may be supplied to the combustion device.

As described in detail, the present invention is summarized as follows. According to one aspect of the present invention, there is provided a combustion device comprising:

• • an outer casing; and
  • a combustion device main body housed in the outer casing, wherein
  • the outer casing has a casing body having a front opening which opens frontward, and a front cover closing the front opening of the casing body and having an exhaust port member insertion hole,
  • the combustion device main body has a burner which ejects mixture gas downward for combustion to generate combustion exhaust gas, a combustion box accommodating therein a heat exchanger heated by the combustion exhaust gas and disposed below the burner, an exhaust duct connected to an outlet port of the combustion box such that the combustion exhaust gas flows therein, and an exhaust port member connected to a downstream end of the exhaust duct to discharge the combustion exhaust gas to an outside,
  • the exhaust duct includes a riser duct section extending from the outlet port of the combustion box to a predetermined position above the burner through behind the combustion device main body, and a horizontal duct section bent from an upper end of the riser duct section, extending toward the front cover, and connected to the exhaust port member,
  • the exhaust port member has an upper wall portion and a lower wall portion separated from each other in an up-down direction, a left wall portion, and a right wall portion such that an exhaust passage is formed inside the exhaust port member,
  • the exhaust port member has an elongated front end opening flat in a left-right direction and an elongated back end opening flat in the left-right direction,
  • the upper wall portion and the lower wall portion of the exhaust port member protrude frontward from an inside of the outer casing through the exhaust port member insertion hole of the front cover,
  • the lower wall portion of the exhaust port member is inclined upward toward the front end opening,
  • an upper inner wall surface of the upper wall portion of the exhaust port member has a first upper inner wall surface portion extending from the front end opening to a predetermined position which is located backward of the front end opening, an upper protruding wall surface portion protruding inward of the exhaust passage from a back end of the first upper inner wall surface portion over the entire exhaust passage in the left-right direction, and a second upper inner wall surface portion extending from an inner end of the upper protruding wall surface portion toward the back end opening,
  • the exhaust passage which is located forward of the upper protruding wall surface portion expands upwardly as compared with the exhaust passage which is located backward of the upper protruding wall surface portion,
  • the second upper inner wall surface portion is inclined upward toward the front end opening, and
  • in a cross section in a front-back direction, an inclination angle of the second upper inner wall surface portion with respect to a horizontal plane is smaller than an inclination angle of a virtual line connecting the inner end of the upper protruding wall surface portion and a front end of the first upper inner wall surface portion forming the front end opening with respect to the horizontal plane.

According to the combustion device described above, the combustion exhaust gas flowing in the exhaust passage of the exhaust port member along the second upper inner wall surface portion is less likely to contact a peripheral edge of the front end opening of the exhaust port member. Further, according to the combustion device described above, drain flowing into the exhaust port member from the exhaust duct or drain generated in the exhaust port member can be returned to the exhaust duct. With this configuration, it is possible to prevent the drain from scattering to the outside from the exhaust port member through the front end opening thereof.

Preferably, in the combustion device described above,

• • a lower inner wall surface of the lower wall portion of the exhaust port member is inclined upward toward the front end opening,
  • the horizontal duct section of the exhaust duct has a duct outlet port connected to the back end opening of the exhaust port member,
  • a duct lower inner wall surface of a duct lower wall portion forming the duct outlet port is inclined upward toward the duct outlet port, and
  • an inclination angle of the lower inner wall surface of the lower wall portion forming the back end opening of the exhaust port member with respect to the horizontal plane is greater than an inclination angle of the duct lower inner wall surface of the duct lower wall portion forming the duct outlet port with respect to the horizontal plane.

According to the combustion device described above, the drain generated in the exhaust duct can be prevented from flowing into the exhaust port member.

Preferably, in the combustion device described above,

• • an inclination angle of a region of the lower inner wall surface facing the second upper inner wall surface portion with respect to the horizontal plane is greater than an inclination angle of the second upper inner wall surface portion with respect to the horizontal plane.

According to the combustion device described above, when the combustion exhaust gas passes through the inside of the exhaust pot member, the combustion exhaust gas is likely to contact the lower inner wall surface as compares with the second upper inner wall surface portion. It is thus that even when the drain is generated in the exhaust port member, the drain can be smoothly returned to the exhaust duct.

Preferably, in the combustion device described above,

• • a protruding portion of the exhaust port member protruding frontward from the exhaust port member insertion hole opening at the front cover has a hanging portion extending downward from a lower surface thereof and a recessed groove recessed upward between the hanging portion and the front cover.

According to the combustion device described above, since the protruding portion protruding frontward through the exhaust port member insertion hole of the front cover has the hanging portion extending downward from the lower surface of the protruding portion, the drain flowing from the front end opening of the exhaust port member flows downward. Further, according to the combustion device described above, since the recessed groove recessed upward is formed between the hanging portion and the front cover, the drain can be dropped downward from the hanging portion. With this configuration, even when the drain scatters from the exhaust port member through the front end opening thereof, flow of the drain toward the front cover along the lower surface of the exhaust port member can be prevented.

Although the present invention has been described hereinabove with reference to exemplary embodiments, the present invention is not limited thereto. The configuration and details of the present invention are open to various modifications within the scope of the present invention that would be clear to those skilled in the art.

INDUSTRIAL APPLICABILITY

According to the present invention, there is provided a combined combustion device capable of preventing drain from scattering from an exhaust port member.