EXHAUST STRUCTURE FOR COMBUSTION APPARATUS

Abstract

An exhaust structure for a combustion apparatus includes a combustion apparatus, an exhaust tube, an exhaust pipe, an exhaust adapter, and a fixing member. The exhaust tube is connected to the combustion apparatus at the one end portion. A part of the exhaust tube on a side of the other end portion is inserted into the exhaust pipe. The exhaust adapter has an annular shape surrounding a through hole, and is attached to an outer circumferential surface of the exhaust tube and to an inner circumferential surface of the exhaust pipe by inserting the exhaust tube into the through hole. The fixing member is formed of an elastic body, attached to the exhaust pipe at a position close to the combustion apparatus relative to the exhaust adapter, and fixes the exhaust tube to the exhaust pipe while being attached to the outer circumferential surface of the exhaust tube.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an exhaust structure for a combustion apparatus.

2. Description of the Background Art

A combustion apparatus, for example, a heating apparatus, has a main body that is placed inside of a building such that an exhaust is emitted through an exhaust pipe (a B vent) to the outside of the building. There are locations where an already-placed exhaust pipe cannot be removed, from a point of view of maintaining appearance of buildings, when this already-placed combustion apparatus should be replaced with a new combustion apparatus.

At such a location, a new exhaust tube (a flexible exhaust tube) is inserted into the already-placed exhaust pipe without removing this already-placed exhaust pipe, so that a combustion apparatus can be replaced. However, if the exhaust tube has a relatively large outer diameter, this exhaust tube cannot be placed inside the exhaust pipe. Accordingly, an exhaust tube decreased in diameter needs to be used.

Furthermore, an exhaust tube inserted into the already-placed exhaust pipe needs to be fixed. In general, a grommet is used as a component for fixing a tube. For example, a grommet is disclosed in Japanese Patent Laying-Open Nos. 2002-152949 and 10-92243.

In the case where a new exhaust tube is inserted into the already-placed exhaust pipe from the inside of a building, the exhaust tube should be fixed while being inserted into the exhaust pipe; otherwise, there may be a problem that the exhaust tube falls from inside of the exhaust pipe into inside of the building.

SUMMARY OF THE INVENTION

The present invention has been made in light of the above-described problems. An object of the present invention is to provide an exhaust structure for a combustion apparatus, by which falling of an exhaust tube inserted into an exhaust pipe can be prevented.

An exhaust structure for combustion apparatus according to the present invention includes a combustion apparatus, an exhaust tube, an exhaust pipe, an exhaust adapter, and a fixing member. The exhaust tube has one end portion and the other end portion, and is connected to the combustion apparatus at the one end portion. A part of the exhaust tube on a side of the other end portion is inserted into the exhaust pipe. The exhaust adapter has an annular shape surrounding a through hole, and is attached to an outer circumferential surface of the exhaust tube and to an inner circumferential surface of the exhaust pipe by inserting the exhaust tube into the through hole. The fixing member is formed of an elastic body, is attached to the exhaust pipe at a position close to the combustion apparatus relative to the exhaust adapter, and fixes the exhaust tube to the exhaust pipe while being attached to the outer circumferential surface of the exhaust tube.

According to the exhaust structure for combustion apparatus of the present invention, the fixing member fixes the exhaust tube to the exhaust pipe in the state where the fixing member is attached to the exhaust pipe and also attached to the outer circumferential surface of the exhaust tube. Accordingly, the fixing member can prevent falling of the exhaust tube inserted into the exhaust pipe.

Furthermore, the fixing member is attached to the exhaust pipe at a position close to the combustion apparatus relative to the exhaust adapter. Accordingly, even before attaching the exhaust adapter, the fixing member can prevent falling of the exhaust tube inserted into the exhaust pipe.

In the exhaust structure for combustion apparatus described above, the fixing member includes a first fixing portion attached to the exhaust tube; a second fixing portion attached to the exhaust pipe; and a main body portion connecting the first fixing portion and the second fixing portion. The main body portion has a communication hole that allows communication between a first region and a second region separated from the first region by the main body portion. The first region is located between the outer circumferential surface of the exhaust tube and the inner circumferential surface of the exhaust pipe. Accordingly, when an exhaust leaks to the first region due to damage of the exhaust tube or the like, the exhaust can be emitted from the first region to the second region through the communication hole.

In the exhaust structure for combustion apparatus described above, the first fixing portion and the second fixing portion each have a cylindrical shape and are concentrically arranged. Accordingly, when the exhaust tube is inserted into the exhaust pipe, the outer circumferential surface of the exhaust tube is less likely to come into contact with the inner circumferential surface of the exhaust pipe. Consequently, the exhaust tube can be readily inserted into the exhaust pipe.

The exhaust structure for combustion apparatus described above further includes a connection pipe connected to the fixing member and the combustion apparatus, and into which a part of the exhaust tube on a side of the one end portion is inserted. The second region is provided between the outer circumferential surface of the exhaust tube and an inner circumferential surface of the connection pipe. The combustion apparatus includes a housing having an internal space. The housing has a connection hole that allows communication between the internal space and the second region. Accordingly, the exhaust tube can be protected by the connection pipe. Furthermore, when an exhaust leaks to the first region due to damage of the exhaust tube and the like, the exhaust can be emitted from the first region through the communication hole to the second region provided between the outer circumferential surface of the exhaust tube and the inner circumferential surface of the connection pipe. Furthermore, the exhaust can be emitted from the second region to the internal space through the connection hole. Accordingly, the exhaust can be prevented from leaking into a room.

In the exhaust structure for combustion apparatus described above, the combustion apparatus is a water heater adapted to an exhaust suction and combustion system. The water heater adapted to the exhaust suction and combustion system can maintain the stabilized combustion state even when the exhaust tube is decreased in diameter.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram schematically showing the state where an exhaust structure for combustion apparatus in one embodiment of the present invention is placed in a building.

FIG. 2 is a partially cutaway perspective view showing, in an enlarged manner, a region II in FIG. 1.

FIG. 3 is a cross-sectional view showing, in an enlarged manner, a region III in FIG. 1.

FIG. 4 is a perspective view schematically showing the configuration of a fixing member included in the exhaust structure for combustion apparatus in one embodiment of the present invention.

FIG. 5 is a cross-sectional view schematically showing the configuration of a modification of the fixing member included in the exhaust structure for combustion apparatus in one embodiment of the present invention.

FIG. 6 is a cross-sectional view showing, in an enlarged manner, a region VI in FIG. 1.

FIG. 7 is a front view schematically showing the configuration of a water heater as an example of a combustion apparatus included in the exhaust structure for combustion apparatus in one embodiment of the present invention.

FIG. 8 is a partial cross-sectional side view schematically showing the configuration of the water heater shown in FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be hereinafter described with reference to the drawings.

An exhaust structure for a combustion apparatus in one embodiment of the present invention will be first described.

Referring to FIG. 1, an exhaust structure for combustion apparatus 100 in the present embodiment mainly has a combustion apparatus 1, an exhaust tube 20, an exhaust pipe 30, an exhaust adapter 40, a fixing member 50, a connection pipe 60, and an exhaust terminal (a rain cap) 70. This exhaust structure for combustion apparatus 100 serves to emit combustion gas produced in combustion apparatus 1 to the outside of a building 200.

Combustion apparatus 1 is placed inside building 200. This combustion apparatus 1 serves as a water heater that heats warm water and water, for example, with combustion gas, and may be a heating apparatus or the like that warms up the inside of the building with combustion gas. Furthermore, in the case where a water heater is used as combustion apparatus 1, this water heater may be, for example, a water heater adapted to an exhaust suction and combustion system. This water heater may also be a water heater of a latent heat recovery type.

Referring to FIGS. 1 and 2, exhaust tube 20 has one end portion 20a and the other end portion 20b. Exhaust tube 20 is connected to combustion apparatus 1 at one end portion 20a. The other end portion 20b of exhaust tube 20 extends to the outside of the building. The inside of exhaust tube 20 is defined as an emission path for the combustion gas emitted from combustion apparatus 1. Thus, the combustion gas produced in combustion apparatus 1 can be guided to the outside of the building through exhaust tube 20.

Exhaust tube 20 is implemented as a flexible pipe such as an accordion pipe, but may be a spiral pipe and the like. This allows exhaust tube 20 to conform also to the shape of exhaust pipe 30 having a complicated shape. Furthermore, since an exhaust flows through exhaust tube 20, this exhaust tube 20 can be suitably made of a material having acidic resistance. This is because acidic drainage water may be discharged together with an exhaust in the case where combustion apparatus 1 is a water heater of a latent heat recovery type as in the present embodiment.

Accordingly, exhaust tube 20 can be made of a material having acidic resistance such as phenol resin, epoxy resin, silicone resin, fluorine resin such as polytetrafluoroethylene, unsaturated polyester resin, melamine resin, polycarbonate resin, methacryl styrene (MS) resin, methacryl resin, styrene acrylonitrile copolymer (AS) resin, ABS resin, polyethylene, polypropylene, polystyrene, polyethylene terephthalate (PET), and vinyl chloride resin, for example.

Exhaust pipe 30 is attached to building 200 so as to extend from the inside to the outside, for example, through a roof 210 of building 200. Exhaust pipe 30 may extend from the inside to the outside through a wall. Exhaust pipe 30 is greater in outer diameter than exhaust tube 20. In the inside of this exhaust pipe 30, a part of exhaust tube 20 on the side of the other end portion 20b is inserted. Exhaust pipe 30 is formed of metal, for example. Exhaust pipe 30 is connected to fixing member 50 at one end portion 30a shown in FIG. 3. Furthermore, exhaust pipe 30 is connected to exhaust terminal 70 at the other end portion 30b.

Exhaust adapter 40 is located on the other end portion 20b side of exhaust tube 20 and also on the other end portion 30b side of exhaust pipe 30. Exhaust adapter 40 has an annular shape that surrounds a through hole. Exhaust adapter 40 is attached to the outer circumferential surface of exhaust tube 20 and also to the inner circumferential surface of exhaust pipe 30 by inserting exhaust tube 20 into the through hole. Specifically, this exhaust adapter 40 is fitted on the outer circumferential surface of exhaust tube 20 and fitted on the inner circumferential surface of exhaust pipe 30. Exhaust adapter 40 has an inner circumferential surface that presses the outer circumferential surface of exhaust tube 20 in the state where this exhaust adapter 40 is fitted on the outer circumferential surface of exhaust tube 20; and an outer circumferential surface that presses the inner circumferential surface of exhaust pipe 30 in the state where exhaust adapter 40 is fitted on the inner circumferential surface of exhaust pipe 30.

Consequently, the inner circumferential surface of exhaust adapter 40 comes into close contact with the outer circumferential surface of exhaust tube 20 while the outer circumferential surface of exhaust adapter 40 comes into close contact with the inner circumferential surface of exhaust pipe 30. Accordingly, exhaust adapter 40 can fix exhaust tube 20 to exhaust pipe 30, and also, can prevent combustion gas or drainage water from leaking through between exhaust tube 20 and exhaust pipe 30 and flowing back into the room.

The above-described configuration can be readily achieved, for example, by exhaust adapter 40 made of an elastic material. This elastic material is for example preferably a soft resin, or for example preferably EPDM (Ethylene-Propylene-Diene Monomer), soft PVC (polyvinyl chloride), silicone rubber, fluororubber, chloroprene rubber (CR), butyl rubber (IIR), or the like. Furthermore, exhaust adapter 40 may be made of one type elastic material, or may be made of a combination of a plurality of different types of elastic materials.

Referring to FIGS. 1 and 3, fixing member 50 serves to fix exhaust tube 20 to exhaust pipe 30. Fixing member 50 fixes exhaust tube 20 to exhaust pipe 30 in the state where it is attached to the outer circumferential surface of exhaust tube 20. Fixing member 50 is attached to exhaust pipe 30 at a position close to combustion apparatus 1 relative to exhaust adapter 40. Furthermore, fixing member 50 fixes connection pipe 60 to exhaust pipe 30.

Fixing member 50 is formed of an elastic body. This elastic body is for example preferably made of a soft resin, or for example preferably EPDM (Ethylene-Propylene-Diene Monomer), soft PVC (polyvinyl chloride), silicone rubber, fluororubber, chloroprene rubber (CR), butyl rubber (IIR), or the like. Furthermore, fixing member 50 may be made of one type elastic material, or may be made of a combination of a plurality of different types of elastic materials.

Referring to FIGS. 3 and 4, fixing member 50 is formed in a tubular shape. Fixing member 50 mainly has a first fixing portion 50a, a second fixing portion 50b, a third fixing portion 50c, and a main body portion 50d.

First fixing portion 50a is formed in a tubular shape. Specifically, first fixing portion 50a has a cylindrical tubular shape. First fixing portion 50a extends from main body portion 50d toward combustion apparatus 1 shown in FIG. 1. It is to be noted that first fixing portion 50a may extend from main body portion 50d toward exhaust terminal 70 shown in FIG. 1.

First fixing portion 50a is attached to exhaust tube 20. Specifically, exhaust tube 20 is introduced into a cylindrical through hole of first fixing portion 50a, and the inner circumferential surface of first fixing portion 50a is in contact with the outer circumferential surface of exhaust tube 20. In other words, first fixing portion 50a is fitted around exhaust tube 20. First fixing portion 50a is formed to have an inner diameter smaller than the outer diameter of exhaust tube 20, thereby allowing exhaust tube 20 to be fixed with the elastic force of first fixing portion 50a. In the present embodiment, a binding band 51 is tightened to squeeze the outer circumferential surface of first fixing portion 50a, so that the inner circumferential surface of first fixing portion 50a is brought firmly into contact with the outer circumferential surface of exhaust tube 20. Thereby, exhaust tube 20 can be firmly fixed by first fixing portion 50a.

Second fixing portion 50b is formed in a tubular shape. Specifically, second fixing portion 50b has a cylindrical tubular shape. Second fixing portion 50b is located outside of first fixing portion 50a in the radial direction of fixing member 50. Second fixing portion 50b extends to the side opposite to the direction in which first fixing portion 50a extends. In other words, second fixing portion 50b extends from main body portion 50d toward exhaust terminal 70 shown in FIG. 1.

Second fixing portion 50b is attached to exhaust pipe 30. Specifically, a part of exhaust pipe 30 on the side of one end portion 30a is introduced into a cylindrical through hole of second fixing portion 50b, and the inner circumferential surface of second fixing portion 50b is in contact with the outer circumferential surface of exhaust pipe 30. In other words, second fixing portion 50b is fitted around exhaust pipe 30. Second fixing portion 50b is formed to have an inner diameter smaller than the outer diameter of exhaust pipe 30, thereby allowing exhaust pipe 30 to be fixed with the elastic force of second fixing portion 50b. In the present embodiment, a binding band 51 is tightened to squeeze the outer circumferential surface of second fixing portion 50b, so that the inner circumferential surface of second fixing portion 50b is brought firmly into contact with the outer circumferential surface of exhaust pipe 30. Thereby, exhaust pipe 30 can be firmly fixed by second fixing portion 50b.

It is to be noted that second fixing portion 50b may be fitted inside exhaust pipe 30. In this case, second fixing portion 50b is formed to have an outer diameter larger than the inner diameter of exhaust pipe 30, thereby allowing exhaust pipe 30 to be fixed with the elastic force of second fixing portion 50b.

Third fixing portion 50c is formed in a tubular shape. Specifically, third fixing portion 50c has a cylindrical tubular shape. Third fixing portion 50c is located outside of first fixing portion 50a in the radial direction of fixing member 50. Furthermore, third fixing portion 50c is located outside of second fixing portion 50b in the radial direction of fixing member 50. Third fixing portion 50c extends to the side opposite to the direction in which second fixing portion 50b extends. In other words, third fixing portion 50c extends from main body portion 50d toward combustion apparatus 1 shown in FIG. 1.

Third fixing portion 50c is attached to connection pipe 60. Specifically, a part of connection pipe 60 on the side of the other end portion 60b is introduced into a cylindrical through hole of third fixing portion 50c, and the inner circumferential surface of third fixing portion 50c is in contact with the outer circumferential surface of connection pipe 60. In other words, third fixing portion 50c is fitted around connection pipe 60. Third fixing portion 50c is formed to have an inner diameter smaller than the outer diameter of connection pipe 60, thereby allowing connection pipe 60 to be fixed with the elastic force of third fixing portion 50c. In the present embodiment, binding band 51 is tightened to squeeze the outer circumferential surface of third fixing portion 50c, so that the inner circumferential surface of third fixing portion 50c is brought firmly into contact with the outer circumferential surface of connection pipe 60. Thereby, connection pipe 60 can be firmly fixed by third fixing portion 50c.

It is to be noted that third fixing portion 50c may be fitted inside connection pipe 60. In this case, third fixing portion 50c is formed to have an outer diameter larger than the inner diameter of connection pipe 60, thereby allowing connection pipe 60 to be fixed with the elastic force of third fixing portion 50c.

Main body portion 50d connects first fixing portion 50a and second fixing portion 50b. Furthermore, main body portion 50d connects second fixing portion 50b and third fixing portion 50c. Main body portion 50d has an annular portion leading to first fixing portion 50a; and a plate-shaped portion leading to this annular portion and second fixing portion 50b. Furthermore, the plate-shaped portion also leads to third fixing portion 50c.

Main body portion 50d has a communication hole 50e. The number of communication holes 50e may be one, or may be two or more. In the present embodiment, a plurality of communication holes 50e are provided. Each communication hole 50e allows communication between a first region R1 and a second region R2 separated from first region R1 by main body portion 50d. First region R1 is located between the outer circumferential surface of exhaust tube 20 and the inner circumferential surface of exhaust pipe 30. In the present embodiment, communication hole 50e is provided in the plate-shaped portion and penetrates through main body portion 50d in the direction in which exhaust tube 20 extends (in the axial direction). Furthermore, communication hole 50e also extends in the circumferential direction of main body portion 50d.

Communication hole 50e is provided in the radial direction of fixing member 50 between the outer circumferential surface of first fixing portion 50a and the inner circumferential surface of second fixing portion 50b. Furthermore, communication hole 50e is provided in the radial direction of fixing member 50 between the outer circumferential surface of first fixing portion 50a and the inner circumferential surface of third fixing portion 50c.

First fixing portion 50a and second fixing portion 50b are concentrically arranged. Accordingly, exhaust tube 20 and exhaust pipe 30 are also concentrically arranged. Furthermore, third fixing portion 50c is also arranged concentrically with first fixing portion 50a and second fixing portion 50b. Accordingly, connection pipe 60 is also arranged concentrically with exhaust tube 20 and exhaust pipe 30.

Referring to FIG. 5, a modification of fixing member 50 in the present embodiment will then be described. In this modification, fixing member 50 has a plurality of slits 50f. Specifically, first fixing portion 50a is provided with a plurality of slits 50f. Each of these slits 50f is formed to extend from the tip end of first fixing portion 50a toward the bottom side thereof. Second fixing portion 50b is also provided with a plurality of slits 50f. Each of these slits 50f is formed to extend from the tip end of second fixing portion 50b toward the bottom side thereof. It is to be noted that third fixing portion 50c may also be provided with a plurality of slits 50f as in first fixing portion 50a.

In the modification of fixing member 50 according to the present embodiment, first fixing portion 50a is provided with a plurality of slits 50f, so that the inner diameter of first fixing portion 50a can be increased and decreased. Accordingly, the inner diameter of first fixing portion 50a can be increased and decreased in accordance with the outer diameter of exhaust tube 20. Thereby, first fixing portion 50a allows fixation of exhaust tubes 20 having a wide range of outer diameters. Furthermore, since first fixing portion 50a is provided with a plurality of slits 50f, it becomes possible to suppress formation of creases in first fixing portion 50a at the time when binding band 51 is tightened to squeeze first fixing portion 50a.

Furthermore, since second fixing portion 50b is also provided with a plurality of slits 50f, the inner diameter of second fixing portion 50b can also be increased and decreased. Accordingly, the inner diameter of second fixing portion 50b can be increased and decreased in accordance with the outer diameter of exhaust pipe 30. Thereby, second fixing portion 50b allows fixation of exhaust pipes 30 having a wide range of outer diameters. Furthermore, since second fixing portion 50b is provided with a plurality of slits 50f, it becomes possible to suppress formation of creases in second fixing portion 50b at the time when binding band 51 is tightened to squeeze second fixing portion 50b. Furthermore, first fixing portion 50a and second fixing portion 50b each are provided with a plurality of slits 50f, thereby allowing combinations of exhaust tubes 20 having a wide range of outer diameters and exhaust pipes 30 having a wide range of outer diameters, respectively.

Referring to FIGS. 1 and 6, connection pipe 60 serves to cover exhaust tube 20 to protect this exhaust tube 20. Connection pipe 60 is connected to fixing member 50 and combustion apparatus 1. Connection pipe 60 is greater in outer diameter than exhaust tube 20. A part of exhaust tube 20 on the side of one end portion 20a is introduced into connection pipe 60.

It is to be noted that connection pipe 60 is implemented as a flexible pipe such as an accordion pipe, but may be a spiral pipe. Connection pipe 60 has flexibility, thereby allowing this connection pipe 60 to readily conform to the shape of exhaust tube 20. Furthermore, connection pipe 60 and combustion apparatus 1 can readily be connected.

Furthermore, connection pipe 60 may be a pipe made of aluminum, for example. In this case, since connection pipe 60 can be reduced in weight, the load on fixing member 50 supporting connection pipe 60 can be decreased. Also, since connection pipe 60 has a certain degree of hardness, it becomes possible to suppress deformation of connection pipe 60 caused by its self-weight. Furthermore, since the pipe made of aluminum can be relatively readily processed, for example, cut and the like, it can readily be adapted to the length of exhaust tube 20, for example.

Second region R2 is provided between the outer circumferential surface of exhaust tube 20 and the inner circumferential surface of connection pipe 60. Furthermore, combustion apparatus 1 includes a housing 9 having an internal space. Housing 9 has a connection hole 9aa that allows communication between the internal space and second region R2. Housing 9 will be described later in detail.

Again referring to FIGS. 1 and 2, exhaust terminal 70 is attached to a tip end of exhaust pipe 30 on the outside of the building. Exhaust terminal 70 has a circumferential wall that is provided with an exhaust port through which combustion gas is emitted to the outside (outdoors). This exhaust port allows the combustion gas guided through exhaust tube 20 to be emitted from exhaust terminal 70 to the outside of building 200 through exhaust pipe 30.

Exhaust terminal 70 may be an outer cover attached on the outer circumferential side of exhaust pipe 30 or may be an inner cover attached on the inner circumferential side of exhaust pipe 30. Exhaust terminal 70 is made, for example, of such a material as aluminum or stainless steel.

Combustion apparatus 1 used in exhaust structure for combustion apparatus 100 described above may be a water heater of a latent heat recovery type, for example, adapted to an exhaust suction and combustion system, as described above. The configuration of the water heater of a latent heat recovery type adapted to the exhaust suction and combustion system will be described below.

Referring to FIGS. 7 and 8, combustion apparatus 1 mainly has a burner 2, a primary heat exchanger 3, a secondary heat exchanger 4, an exhaust box 5, a fan 6, a connection pipe 7, a drainage water tank 8, a housing 9, and pipes 10 to 16.

Burner 2 serves to produce combustion gas by burning fuel gas. A gas supply pipe 11 is connected to burner 2. This gas supply pipe 11 serves to supply fuel gas to burner 2. A gas valve (not shown) implemented, for example, by an electromagnetic valve is attached to this gas supply pipe 11.

A spark plug 2a is disposed above burner 2. This spark plug 2a serves to ignite an air fuel mixture injected from burner 2 to thereby produce a flame, by generating sparks between the plug and a target (not shown) provided in burner 2 by activating an ignition device (an igniter). Burner 2 generates a quantity of heat by burning fuel gas supplied from gas supply pipe 11 (which is called a combustion operation).

Primary heat exchanger 3 is a heat exchanger of a sensible heat recovery type. This primary heat exchanger 3 mainly has a plurality of plate-shaped fins 3b, a heat conduction pipe 3a penetrating the plurality of plate-shaped fins 3b, and a case 3c accommodating fins 3b and heat conduction pipe 3a. Primary heat exchanger 3 exchanges heat with the combustion gas generated by burner 2, and specifically, it serves to heat hot water and water which flows through heat conduction pipe 3a of primary heat exchanger 3 with the quantity of heat generated as a result of the combustion operation of burner 2.

Secondary heat exchanger 4 is a heat exchanger of a latent heat recovery type. This secondary heat exchanger 4 is located downstream of primary heat exchanger 3 in a flow of the combustion gas and connected in series with primary heat exchanger 3. Since combustion apparatus 1 according to the present embodiment thus has secondary heat exchanger 4 of a latent heat recovery type, it serves as a water heater of a latent heat recovery type.

Secondary heat exchanger 4 mainly has a drainage water discharge port 4a, a heat conduction pipe 4b, a sidewall 4c, a bottom wall 4d, and an upper wall 4g. Heat conduction pipe 4b is layered as it is spirally wound. Sidewall 4c, bottom wall 4d and upper wall 4g are arranged to surround heat conduction pipe 4b.

In secondary heat exchanger 4, hot water and water which flows through heat conduction pipe 4b is pre-heated (heated) through heat exchange with the combustion gas of which heat has been exchanged in primary heat exchanger 3. As a temperature of the combustion gas is lowered to approximately 60° C. through this process, moisture contained in the combustion gas is condensed so that latent heat can be obtained. In addition, latent heat is recovered in secondary heat exchanger 4 and moisture contained in the combustion gas is condensed, whereby drainage water is produced.

Bottom wall 4d serves as a partition between primary heat exchanger 3 and secondary heat exchanger 4, and it also serves as an upper wall of primary heat exchanger 3. This bottom wall 4d is provided with an opening portion 4e, and this opening portion 4e allows communication between a space where heat conduction pipe 3a of primary heat exchanger 3 is arranged and a space where heat conduction pipe 4b of secondary heat exchanger 4 is arranged. As shown by hollow arrows in FIG. 8, the combustion gas can flow from primary heat exchanger 3 to secondary heat exchanger 4 through opening portion 4e. In this embodiment, for the sake of simplification, although one common component is employed for bottom wall 4d of secondary heat exchanger 4 and the upper wall of primary heat exchanger 3, an exhaust collection and guide member may be connected between primary heat exchanger 3 and secondary heat exchanger 4.

Upper wall 4g is provided with an opening portion 4h, and this opening portion 4h allows communication between the space where heat conduction pipe 4b of secondary heat exchanger 4 is arranged and an internal space in exhaust box 5. As shown by hollow arrows in FIG. 8, the combustion gas can flow from secondary heat exchanger 4 into the internal space in exhaust box 5 through opening portion 4h.

Drainage water discharge port 4a is provided in sidewall 4c or bottom wall 4d. This drainage water discharge port 4a opens at a lowest position in the space surrounded by side wall 4c, bottom wall 4d and upper wall 4g (the lowermost position in the vertical direction in the state where the water heater is placed), which is lower than the lowermost portion of heat conduction pipe 4b. Thus, drainage water produced in secondary heat exchanger 4 can be guided to drainage water discharge port 4a along bottom wall 4d and sidewall 4c as shown by a black arrow in FIG. 8.

Exhaust box 5 forms a path for a flow of the combustion gas between secondary heat exchanger 4 and fan 6. This exhaust box 5 can guide, to fan 6, the combustion gas of which heat has been exchanged in secondary heat exchanger 4. Exhaust box 5 is attached to secondary heat exchanger 4 and located downstream of secondary heat exchanger 4 in the flow of the combustion gas.

Exhaust box 5 mainly has a box main body 5a and a fan connection portion 5b. An internal space in box main body 5a communicates through opening portion 4h in secondary heat exchanger 4 with the internal space where heat conduction pipe 4b of secondary heat exchanger 4 is arranged. Fan connection portion 5b is provided so as to protrude from an upper portion of box main body 5a. This fan connection portion 5b has, for example, a cylindrical shape, and an internal space 5ba thereof communicates with the internal space in box main body 5a.

Fan 6 serves to emit the combustion gas (of which heat has been exchanged in secondary heat exchanger 4), which has passed through secondary heat exchanger 4, to the outside of combustion apparatus 1 by suctioning the combustion gas. This fan 6 is located downstream of exhaust box 5 and secondary heat exchanger 4 in the flow of the combustion gas. Namely, in combustion apparatus 1, burner 2, primary heat exchanger 3, secondary heat exchanger 4, exhaust box 5, and fan 6 are arranged in this order from upstream to downstream in the flow of the combustion gas produced in burner 2. Since the combustion gas is suctioned and exhausted by means of fan 6 as above in this arrangement, combustion apparatus 1 in the present embodiment is a water heater adapted to the exhaust suction and combustion system.

Fan 6 mainly has a rotor 6a, a fan case 6b, a drive source 6c, and a rotation shaft 6d. Fan case 6b is attached to fan connection portion 5b of exhaust box 5 such that the internal space in fan case 6b and the internal space in fan connection portion 5b communicate with each other. Thus, as shown by the hollow arrows in FIG. 8, the combustion gas can be suctioned from box main body 5a of exhaust box 5 through fan connection portion 5b into fan case 6b.

Rotor 6a is arranged in fan case 6b. This rotor 6a is connected to drive source 6c with rotation shaft 6d interposed therebetween. Thus, rotor 6a is provided with drive force from drive source 6c and can rotate around rotation shaft 6d. By rotation of rotor 6a, the combustion gas in exhaust box 5 can be suctioned from the inner circumferential side of rotor 6a and can be emitted to the outer circumferential side of rotor 6a.

Connection pipe 7 is connected to a region within fan case 6b, on the outer circumferential side of a region where rotor 6a is arranged. Therefore, the combustion gas emitted to the outer circumferential side of rotor 6a by rotor 6a of fan 6 can be emitted into exhaust tube 20 through connection pipe 7.

The combustion gas produced by burner 2 as above is suctioned by fan 6 by rotation of rotor 6a above, so that the combustion gas can reach fan 6 after passage through primary heat exchanger 3, secondary heat exchanger 4 and exhaust box 5 in this order as shown by the hollow arrows in FIG. 8 and can be emitted to the outside of combustion apparatus 1.

Drainage water tank 8 serves to store drainage water produced in secondary heat exchanger 4. This drainage water tank 8 is connected to secondary heat exchanger 4 through pipe 10. Pipe 10 is connected to drainage water discharge port 4a of secondary heat exchanger 4. Thus, the drainage water produced in secondary heat exchanger 4 can be discharged to drainage water tank 8. A pipe 15 extending to the outside of combustion apparatus 1 is connected to drainage water tank 8. The drainage water stored in drainage water tank 8 can be discharged to the outside of combustion apparatus 1 through this pipe 15.

This drainage water tank 8 has a water seal structure. Namely, drainage water tank 8 has such a structure that, when a prescribed amount of drainage water is stored in drainage water tank 8, the stored drainage water cannot allow air to pass through drainage water tank 8. By such a water seal structure of drainage water tank 8, entry of air outside combustion apparatus 1 (outside air) into combustion apparatus 1 (secondary heat exchanger 4) through drainage water tank 8 via pipe 15 can be prevented.

It is to be noted that the lower portion of drainage water tank 8 is connected to a pipe 16 for discharging drainage water, separately from pipe 15. This pipe 16 (usually closed) for discharging drainage water is designed such that drainage water within drainage water tank 8 that cannot be discharged through pipe 15 can be discharged by opening this pipe 16 during maintenance and the like. Furthermore, drainage water tank 8 has an internal space that may contain a neutralizing agent (not shown) for neutralizing acidic drainage water.

A water supply pipe 12 is connected to one end of heat conduction pipe 4b of secondary heat exchanger 4 and a hot water delivery pipe 13 is connected to one end of heat conduction pipe 3a of primary heat exchanger 3. The other end of heat conduction pipe 3a of primary heat exchanger 3 and the other end of heat conduction pipe 4b of secondary heat exchanger 4 are connected to each other through a pipe 14. Each of gas supply pipe 11, water supply pipe 12 and hot water delivery pipe 13 described above leads to the outside, for example, in a top portion of combustion apparatus 1. Burner 2, primary heat exchanger 3, secondary heat exchanger 4, exhaust box 5, fan 6, drainage water tank 8, and the like are arranged in housing 9.

Again referring to FIGS. 6 and 7, housing 9 has a connection portion 9a and an exhaust portion 9b. Specifically, housing 9 has an upper surface provided with tubular connection portion 9a and tubular exhaust portion 9b that are concentrically arranged and protrude in the upward direction. In other words, connection portion 9a and exhaust portion 9b form a double-pipe structure.

Connection portion 9a is provided so as to surround the outer circumferential surface of exhaust portion 9b. Furthermore, connection hole 9aa is provided in a region of housing 9 between the outer circumferential surface of exhaust portion 9b and the inner circumferential surface of connection portion 9a. An exhaust port 9bb is provided inside exhaust portion 9b of housing 9. Connection hole 9aa communicates with the inside of housing 9 while exhaust port 9bb communicates with the inside of connection pipe 7. Accordingly, second region R2 provided between the outer circumferential surface of exhaust tube 20 and the inner circumferential surface of connection pipe 60 communicates with the internal space of housing 9 through connection hole 9aa provided in housing 9. Furthermore, the combustion gas having flown through burner 2 is sent from connection pipe 7 to exhaust tube 20 via exhaust portion 9b.

Connection portion 9a is connected to connection pipe 60 on the one end portion 60a side thereof while exhaust portion 9b is connected to exhaust tube 20 on the one end portion 20a side thereof. In addition, exhaust portion 9b is connected also to connection pipe 7 housed within housing 9. For example, exhaust portion 9b is formed to protrude also downward in a tubular manner from the upper surface of housing 9, so that exhaust portion 9b and connection pipe 7 can be readily connected to each other.

Connection portion 9a and connection pipe 60 only have to be connected to each other so as to prevent leakage of the gas flowing therethrough. Similarly, exhaust portion 9b and exhaust tube 20 (and connection pipe 7) only have to be connected to each other so as to prevent leakage of the gas flowing therethrough. Accordingly, an O-ring may be interposed between these components connected to each other, or these components may be firmly bound using a binding band. It is to be noted that connection between these components may be implemented by an inner cover or an outer cover.

Then, the functions and effects of the present embodiment will be described.

As described above, in the case where combustion apparatus 1 already placed inside the building is replaced with a new combustion apparatus 1, the already-placed exhaust pipe 30 is left unremoved and a new exhaust tube 20 is inserted into this already-placed exhaust pipe 30, so that combustion apparatus 1 can be replaced. In other words, an exhaust produced in combustion apparatus 1 is to be guided through exhaust tube 20 inserted into exhaust pipe 30, and emitted to the outside of a building.

In the case where a new exhaust tube 20 is inserted into the already-placed exhaust pipe 30 from inside of the building, exhaust tube 20 may fall into inside of the building from inside of exhaust pipe 30 if exhaust tube 20 is merely inserted into exhaust pipe 30 but not fixed in this state.

According to exhaust structure for combustion apparatus 100 of the present embodiment, as shown in FIG. 3, exhaust tube 20 is fixed to exhaust pipe 30 in the state where second fixing portion 50b of fixing member 50 is attached to exhaust pipe 30 and first fixing portion 50a is attached to the outer circumferential surface of exhaust tube 20. Accordingly, fixing member 50 can prevent falling of exhaust tube 20 inserted into exhaust pipe 30.

Furthermore, fixing member 50 is attached to exhaust pipe 30 at a position close to combustion apparatus 1 relative to exhaust adapter 40. Even in the case where exhaust tube 20 can be fixed to exhaust pipe 30 by exhaust adapter 40, exhaust tube 20 cannot be fixed until it reaches exhaust adapter 40 since exhaust tube 20 is inserted into exhaust pipe 30 from inside of the building. According to the present embodiment, since fixing member 50 is attached to exhaust pipe 30 at a position close to combustion apparatus 1 relative to exhaust adapter 40, fixing member 50 can prevent falling of exhaust tube 20, which is inserted into exhaust pipe 30, even before exhaust adapter 40 is attached.

In exhaust structure for combustion apparatus 100 according to the present embodiment, as shown in FIG. 3, fixing member 50 is provided with communication hole 50e that allows communication between first region R1 and second region R2. Accordingly, in the case where an exhaust leaks to first region R1 due to damage of exhaust tube 20 or the like, the exhaust can be emitted from first region R1 to second region R2 through communication hole 50e.

In exhaust structure for combustion apparatus 100 according to the present embodiment, as shown in FIG. 3, first fixing portion 50a and second fixing portion 50b each have a cylindrical shape and are concentrically arranged. Accordingly, when exhaust tube 20 is inserted into exhaust pipe 30, the outer circumferential surface of exhaust tube 20 is less likely to come into contact with the inner circumferential surface of exhaust pipe 30. Thereby, exhaust tube 20 can be readily inserted into exhaust pipe 30.

In exhaust structure for combustion apparatus 100 according to the present embodiment, as shown in FIG. 1, a part of exhaust tube 20 is inserted into connection pipe 60. Accordingly, exhaust tube 20 can be protected by connection pipe 60 from ultraviolet light or force applied from outside.

Furthermore, as shown in FIG. 6, housing 9 has connection hole 9aa that allows communication between the internal space and second region R2 that is provided between the outer circumferential surface of exhaust tube 20 and the inner circumferential surface of connection pipe 60. Accordingly, in the case where damage of exhaust tube 20 or the like causes leakage of an exhaust to first region R1 between the outer circumferential surface of exhaust tube 20 and the inner circumferential surface of exhaust pipe 30, this exhaust can be emitted from first region R1 through communication hole 50e to second region R2 provided between the outer circumferential surface of exhaust tube 20 and the inner circumferential surface of connection pipe 60. Furthermore, an exhaust can be emitted from second region R2 to the internal space through connection hole 9aa. Consequently, leakage of an exhaust into a room can be prevented.

In the exhaust structure for combustion apparatus according to the present embodiment, as shown in FIG. 7, combustion apparatus 1 is a water heater adapted to an exhaust suction and combustion system. The water heater adapted to an exhaust suction and combustion system can maintain a stabilized combustion state even in the case where exhaust tube 20 is decreased in diameter.

In other words, since combustion apparatus 1 serving as a water heater adapted to an exhaust suction and combustion system is used, the combustion operation by burner 2 can be stabilized for the water heater of a so-called an exhaust pushing type even in the case where exhaust tube 20 is decreased in diameter, which will be hereinafter described.

In the water heater of a so-called exhaust pushing type, a fan, a burner, a primary heat exchanger, and a secondary heat exchanger are arranged in this order from upstream to downstream in the flow of the combustion gas. In other words, the combustion gas produced by the burner is guided by the fan to flow through the primary heat exchanger and the secondary heat exchanger into the exhaust tube provided outside of the water heater.

The combustion gas pushed out by the fan receives flow path resistance caused by the primary heat exchanger and the secondary heat exchanger before this combustion gas reaches the exhaust tube. Accordingly, the blast pressure of the combustion gas immediately in front of the exhaust tube is lowered by this flow path resistance. For this reason, the blast pressure caused by the fan should be raised in order to push the combustion gas into the exhaust tube having a relatively small diameter. However, when the blast pressure of the fan is raised, the internal pressure within the burner case is raised. Consequently, in the case where the fuel gas is supplied to the burner at relatively low pressure, the combustion operation becomes unstable.

On the other hand, according to the exhaust suction and combustion system in the present embodiment, burner 2, primary heat exchanger 3, secondary heat exchanger 4, and fan 6 are arranged in this order from upstream to downstream in the flow of the combustion gas. In this system, negative pressure occurs on the upstream side of fan 6, which eliminates the need to raise the blast pressure of fan 6. Accordingly, even in the case where exhaust tube 20 is decreased in diameter, the internal pressure within the burner case can be maintained low. Therefore, the combustion operation can be stabilized even if the fuel gas is supplied to burner 2 at relatively low pressure.

Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the scope of the present invention being interpreted by the terms of the appended claims.

Claims

1. An exhaust structure for combustion apparatus, comprising: a combustion apparatus;an exhaust tube having one end portion and the other end portion, and connected to said combustion apparatus at said one end portion;an exhaust pipe, in which a part of said exhaust tube on a side of said other end portion being inserted;an exhaust adapter having an annular shape surrounding a through hole, and attached to an outer circumferential surface of said exhaust tube and to an inner circumferential surface of said exhaust pipe by inserting said exhaust tube into said through hole; anda fixing member formed of an elastic body, attached to said exhaust pipe at a position close to said combustion apparatus relative to said exhaust adapter, and fixing said exhaust tube to said exhaust pipe while being attached to the outer circumferential surface of said exhaust tube.

2. The exhaust structure for combustion apparatus according to claim 1, wherein said fixing member includes a first fixing portion attached to said exhaust tube,a second fixing portion attached to said exhaust pipe, anda main body portion connecting said first fixing portion and said second fixing portion, andsaid main body portion has a communication hole that allows communication between a first region and a second region separated from said first region by said main body portion, said first region being located between the outer circumferential surface of said exhaust tube and the inner circumferential surface of said exhaust pipe.

3. The exhaust structure for combustion apparatus according to claim 2, wherein said first fixing portion and said second fixing portion each have a cylindrical shape and are concentrically arranged.

4. The exhaust structure for combustion apparatus according to claim 2, further comprising a connection pipe connected to said fixing member and said combustion apparatus, a part of said exhaust tube on a side of said one end portion being inserted into said connection pipe, wherein said second region is provided between the outer circumferential surface of said exhaust tube and an inner circumferential surface of said connection pipe,said combustion apparatus includes a housing having an internal space, andsaid housing has a connection hole that allows communication between said internal space and said second region.

5. The exhaust structure for combustion apparatus according to claim 1, wherein said combustion apparatus is a water heater adapted to an exhaust suction and combustion system.