Water heater piping connection structure

Abstract

To provide a piping connection structure of a water heater which is excellent in productivity and an attachment property.SOLUTION: A piping connection structure 2 of a water heater 1 comprises a female-side pipe F, a male-side pipe M, a quick fastener 51, and a lock nut 60. A pair of arm parts 53, 53 have a pair of clearances 55, 55 which are formed between first arm parts 53B, 53B and a pair of second arm parts 53D, 53D in an axial direction of the male-side pipe M, and introduction ports 56 formed between tip prats of a pair of the arm parts 53, 53, and introducing the male-side pipe M and the female-side pipe F between a pair of the arm parts 53, 53. The lock nut 60 has an insertion part 64 in which the male-side pipe M is inserted, guide ports 63 communicating with the insertion part 64, and guiding the male-side pipe M into the insertion part 64 are formed at tip parts of a pair of arm parts 62, 62, and a positioning part 62A for positioning the lock nut 60 in the clearance 55 in a state that orientations of the introduction ports 56 and the guide ports 63 are aligned when the lock nut 60 is inserted into a pair of the clearances 55, 55 of the quick fastener 51 is formed at the lock nut 60.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a pipe connection structure for a water heater. [Background technology]

[0002] As a pipe connection structure for connecting pipes, for example, a pipe connector described in Japanese Patent Laid-Open Publication No. 8-170765 (Patent Document 1 below) is known. This pipe connector includes a male connector provided at the end of one pipe, a female connector provided at the end of the other pipe connected to the one pipe, and a locking C-ring. The male connector includes an annular rib provided at the tip of the one pipe, a locking disk fixed to the one pipe at a certain distance from the annular rib, and an O-ring positioned between the annular rib and the locking disk and fitted to the one pipe. The female connector includes a cylindrical body fixed to the end of the other pipe, and a flange portion extending radially outward from the tip of the cylindrical body. The locking C-ring includes a band-shaped arc-shaped main body bent into an arc, and a bent guide bent outward at the tip side of the arc-shaped main body.

[0003] A bent apex portion is formed in the center of the arc-shaped main body, which is bent outward in a mountain shape. A pair of elongated slits is formed in the area extending from the arc-shaped main body excluding the bent apex portion to a part of the bent guide. The width of the slit is set to be slightly larger than the axial thickness of the locking disk and the flange portion when the connecting male device and the connecting female device are connected. Therefore, when the tip of the connecting male device is inserted into the inside of the cylindrical body of the connecting female device, the locking disk and the flange portion are brought into contact with each other, and the locking C-ring is attached so that the locking disk and the flange portion fit into the slit, the locking disk and the flange portion are held in a non-disconnecting state via the locking C-ring, and the connecting male device and the connecting female device are connected.

[0004] The locking disk is fixed to one of the pipes as follows. First, a tubular portion is provided that protrudes axially from the inner peripheral edge of the locking disk toward the annular rib, and a ring-shaped groove is formed on the inner peripheral surface of the tubular portion. Next, the locking disk and the tubular portion are loosely fitted into a middle portion of one of the pipes that is spaced apart from the end of the pipe in the axial direction, and then a tying process is performed on the portion of the one of the pipes that corresponds to the groove toward the groove to form a tying portion. As a result, the locking disk is fixed to the middle portion of one of the pipes by the frictional force between the tying portion and the groove. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 8-170765 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the above-mentioned pipe connector, the operation of fixing the locking disk to one of the pipes is complicated, which is disadvantageous in terms of productivity and ease of installation.

[0007] The present invention was developed in light of the above circumstances, and an object of the present invention is to provide a pipe connection structure for a water heater which is excellent in productivity and installation properties. [Means for solving the problem]

[0008] a male side pipe opening at a tip end and having an annular rib formed at a tip end thereof such that the annular rib enters an area surrounded by the flange portion when the tip end of the male side pipe fits into the tip end of the female side pipe; a clip fitted onto the outer circumferential surface of the male side pipe and the outer circumferential surface of the female side pipe in a fitted state; and a washer arranged to surround the male side pipe by a pair of arms and a connecting portion connecting the pair of arms together, the washer being capable of coming into close contact with the flange portion and the annular rib within the flange portion from the male side pipe side, the clip comprising a base end side connecting portion and a pair of clamping pieces extending in an opposing arrangement from the base end side connecting portion, the pair of clamping pieces being a pair of female side clamping pieces that clamp the female side pipe, and an inlet formed between the tips of the pair of clamping pieces for introducing the male side pipe and the female side pipe between the pair of clamping pieces, the inlet having an inner diameter dimension corresponding to an outer diameter dimension of the tip of the male side pipe, the tips of the pair of arms having guide ports communicating with the insertion ports and guiding the male side pipe into the insertion ports, and at least one of the washer and the clip having a positioning portion formed therein for positioning the washer within the gap with the orientation of the inlet and the guide port aligned when the washer is inserted into the pair of gaps of the clip. Effect of the Invention

[0009] According to the present invention, a pipe connection structure for a water heater that is excellent in productivity and ease of installation can be provided. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a front view illustrating a schematic internal structure of a water heater according to an embodiment. [Diagram 2] FIG. 2 is an explanatory diagram conceptually showing the configuration of the water heater. [Diagram 3] FIG. 3 is a partially enlarged front view conceptually illustrating the internal structure of the water heater. [Figure 4] FIG. 4 is a partially enlarged rear view conceptually illustrating the internal structure of the water heater. [Diagram 5] FIG. 5 is a partially enlarged perspective view of the internal structure of the water heater as viewed from the upper left. [Figure 6] FIG. 6 is a partially enlarged perspective view of the internal structure of the water heater as viewed from the upper right. [Figure 7] FIG. 7 is a perspective view of a pipe connecting member. [Figure 8] FIG. 8 is a front view of the pipe connecting member. [Figure 9] FIG. 9 is a cross-sectional view showing a locking structure between a quick fastener and a lock nut. [Figure 10] FIG. 10 is a perspective view showing the male side tube and the female side tube in a state prior to being connected. [Figure 11] FIG. 11 is a perspective view showing the state in which the tip of the male side pipe is fitted into the tip of the female side pipe and the pipe connecting member has not yet been attached to the male side pipe and the female side pipe. [Figure 12] FIG. 12 is a perspective view of a pipe connection structure in which a pipe connection member is attached to a male side pipe and a female side pipe, as viewed obliquely from above. [Figure 13] 13 is a cross-sectional view of the pipe connection structure of FIG. 12 taken along a radial direction perpendicular to the axial direction of the male side pipe at the position of the lock nut. [Figure 14] 14 is a cross-sectional view of the pipe connection structure of FIG. 12 taken along the axial direction of the male side pipe at the position of the axis of the male side pipe. [Figure 15] FIG. 15 is a cross-sectional view showing a state in the middle of provisionally assembling the lock nut to the quick fastener. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, embodiments of the present disclosure will be listed and illustrated. (1) A pipe connection structure for a water heater disclosed herein comprises: a female side pipe that opens to a tip side, the female side pipe having a flange portion formed on an outer peripheral surface of a tip of the female side pipe that extends radially outward; a male side pipe that opens to a tip side, the male side pipe having an annular rib formed on a tip portion of the male side pipe, the tip portion of the male side pipe fitting into the tip portion of the female side pipe so that the annular rib enters an area surrounded by the flange portion; a clip that is fitted onto the outer peripheral surface of the male side pipe and the outer peripheral surface of the female side pipe in a fitted state; and a washer that is arranged to surround the male side pipe by a pair of arms and a connecting portion that connects the pair of arms together, and is capable of coming into close contact with the flange portion and the annular rib in the flange portion from the male side pipe side, the clip comprises a base end side connecting portion and a pair of clamping pieces extending in an opposing arrangement from the base end side connecting portion, the pair of clamping pieces being a pair of female side clamping pieces that clamp the female side pipe. and a pair of gaps formed between the pair of female clamping pieces and the pair of male clamping pieces in the axial direction of the male side pipe, into which the flange portion and the washer fit, and an inlet formed between the tips of the pair of clamping pieces for introducing the male side pipe and the female side pipe between the pair of clamping pieces, the washer has an insertion portion through which the male side pipe is inserted, the inner diameter dimension of the insertion portion being formed to correspond to the outer diameter dimension of the tip of the male side pipe, the tips of the pair of arms are formed with guide ports that communicate with the insertion portions and guide the male side pipe into the insertion portion, and at least one of the washer and the clip is formed with a positioning portion that positions the washer within the gap with the orientation of the inlet and the guide port aligned when the washer is inserted into the pair of gaps of the clip.

[0012] Since the clip has a positioning portion that positions the washer in the gap with the introduction port and guide port oriented in the same direction when the washer is inserted into a pair of gaps, the washer can be prevented from shifting position relative to the clip when the washer is temporarily assembled to the clip. Therefore, the washer can be handled as a single unit in the temporarily assembled state, and the washer can be attached to the male tube by attaching the clip to the male tube and the female tube, improving the ease of assembly of the clip and washer.

[0013] (2) It is preferable that a protruding portion protruding in a direction away from the insertion portion is formed on a portion of the arm portion that is disposed outside the clamping piece from the gap. For example, if the shape of the washer is primarily disk-shaped, like the locking disk described in the background art, when it is temporarily assembled to a clip in which the arc portions of both the male and female clamping pieces have a large radius of curvature, the outer edge of the washer and the arc portions of the clamping pieces will be close to each other, and depending on the force applied to the washer, the washer may shift to the inside of the arc portions, compromising assembly. Therefore, by providing a protruding portion that protrudes significantly outward from the clamping piece, it is possible to prevent the washer from falling out of the gap during temporary assembly.

[0014] (3) It is preferable that the protruding portion is formed in at least two places symmetrically with respect to an imaginary line connecting the centers of the insertion portion and the guide port. Since the protruding portions are formed in at least two places, the washer can be more effectively prevented from falling off the clip.

[0015] (4) It is preferable that the protruding portion is provided at an end portion opposite the guide opening with respect to the insertion portion. Since the protruding portion is provided at the end of the washer opposite the guide opening, the protruding portion can be used as a guide when inserting the washer into the gap of the clip, improving the ease of temporary assembly.

[0016] (5) At the end of the arm portion opposite the protrusion portion, an extension portion is formed which extends in a direction away from the connecting portion when the washer is positioned within the gap, a pair of extension portions are provided on each of the pair of arms, and it is preferable that the guide hole of the washer is formed between the pair of extension portions when the washer is temporarily assembled to the clip. Since the extension and protrusion are formed on both ends of the arm, respectively, the washer can be provisionally assembled with the extension and protrusion protruding from the clip, and in the provisionally assembled state the washer can be more stably held within the clip, preventing problems such as the washer falling off the clip when attached to both male and female tubes.

[0017] (6) The tip of the female clamping piece and the tip of the male clamping piece are connected to each other by a tip side connecting portion, and a tapered portion is formed between the protrusion portion and the positioning portion at the outer edge of the washer, and it is preferable that when the washer is inserted into the pair of gaps of the clip, the tapered portion slides against the tip side connecting portion, thereby opening the pair of clamping pieces. When the washer is inserted into the pair of gaps in the clip, the tapered portion slides against the tip side connecting portion, opening the pair of clamping pieces, so there is no need to use a large amount of force to open the pair of clamping pieces before inserting the washer; the pair of clamping pieces can be opened simply by pushing the washer in, and the washer can be attached to the clip with a relatively small force.

[0018] <Embodiment> Hereinafter, embodiments will be described with reference to the drawings.

[0019] [Overall structure of the water heater] As shown in Figs. 1 to 4, the water heater 1 includes a primary heat exchange device 100, a secondary heat exchange device 200, a burner device 300, an exhaust hood 400, and the like. The primary heat exchange device 100 includes two heat exchangers: a hot water supply primary heat exchanger 110 and a bath primary heat exchanger 120 .

[0020] The secondary heat exchange device 200 is disposed above the primary heat exchange device 100. The secondary heat exchange device 200 includes two heat exchangers: a hot water supply secondary heat exchanger 210 connected to the upstream side of the hot water supply primary heat exchanger 110, and a bath secondary heat exchanger 220 connected to the upstream side of the bath primary heat exchanger 120.

[0021] The burner device 300 is connected to the lower part of the primary heat exchange device 100. The burner device 300 includes two burner groups, a hot water supply burner group 310 and a bathtub burner group 320, and a burner case 330. The hot water supply burner group 310 generates combustion exhaust gas to be sent to the hot water supply primary heat exchanger 110 and the hot water supply secondary heat exchanger 210. The bathtub burner group 320 generates combustion exhaust gas to be sent to the bathtub primary heat exchanger 120 and the bathtub secondary heat exchanger 220.

[0022] The exhaust hood 400 has a lower end connected to the primary heat exchange device 100 and an upper end connected to the secondary heat exchange device 200. The lower end of the exhaust hood 400 opens downward and communicates with the space inside the primary heat exchange device 100. The upper end of the exhaust hood 400 opens forward and communicates with the space inside the secondary heat exchange device 200. The combustion exhaust gas of the burner device 300 is guided from the primary heat exchange device 100 through the exhaust hood 400 to the secondary heat exchange device 200.

[0023] The water heater 1 circulates the combustion exhaust gas generated in each burner group 310, 320 of the burner device 300 to the primary heat exchange device 100 above the burner device 300. In the primary heat exchange device 100, heat is exchanged between the combustion exhaust gas and the water passing through the hot water supply primary heat exchanger 110 and the bath primary heat exchanger 120. The water heater 1 functions to recover sensible heat of the combustion exhaust gas by the primary heat exchange device 100.

[0024] The combustion exhaust gas that has passed through the primary heat exchanger 100 passes through an exhaust hood 400 and enters the secondary heat exchanger 200 from the rear. In the secondary heat exchanger 200, heat is exchanged between the combustion exhaust gas and the water passing through the hot water supply secondary heat exchanger 210 and the bath secondary heat exchanger 220. The water heater 1 functions to recover the latent heat of the combustion exhaust gas by the secondary heat exchanger 200.

[0025] [Water heater circuit configuration] As shown in FIG. 2, the water heater 1 is configured to include two circuits: a hot water supply circuit 10 and a bath circuit 20. The hot water supply circuit 10 is a circuit that heats water from a water supply or the like and flows it out as hot water. As shown in Figures 1 and 2, the hot water supply circuit 10 flows water into a water inlet pipe 12 from a water inlet 11 connected to a water supply source such as a water supply, passes the water through a hot water supply secondary heat exchanger 210 and a hot water supply primary heat exchanger 110 in this order, and heats the water by exchanging heat with the combustion exhaust gas from a hot water supply burner group 310. The water flows through a hot water outlet pipe 13 and flows out from a hot water outlet 14.

[0026] The bath circuit 20 is a circuit that circulates and heats the hot water in the bathtub B. The bath circuit 20 uses a circulation pump P to draw the hot water in the bathtub B into a return pipe 22 from a hot water inlet 21 that is connected to an opening in the bathtub B, and while passing the water through the bath secondary heat exchanger 220 and the bath primary heat exchanger 120 in that order, it reheats the hot water by exchanging heat with the combustion exhaust gas from the bath burner group 320, and discharges the hot water, which has become hotter, from a hot water outlet 24 via a forward pipe 23 into the bathtub B.

[0027] 1 and 2, the water heater 1 includes a drain hose 31 and a neutralizer 32. The upstream side of the drain hose 31 is connected to a drain outlet 238 of the secondary heat exchange device 200, and the downstream side is connected to the neutralizer 32. Drain generated by the recovery of latent heat in the secondary heat exchange device 200 is discharged to the outside of the secondary heat exchange device 200 via the drain outlet 238, and is sent to the neutralizer 32 through the drain hose 31.

[0028] As shown in Fig. 1, the water heater 1 includes a controller 33 as a control device. The controller 33 is configured, for example, as a known microcomputer or the like, and is configured to be able to acquire signals from various sensors provided in the water heater 1, and is configured to be able to control various actuators provided in the water heater 1. For example, when the water heater 1 detects the flow of water in the water inlet pipe 12 by a water flow sensor (not shown), it operates the hot water supply burner group 310 to generate hot water. As another example, when the water heater 1 detects the flow of water in the return pipe 22 by a water flow sensor (not shown), it operates the bath burner group 320 to reheat the bath.

[0029] [Primary heat exchange device] Next, the configuration of the primary heat exchange device 100 will be described. The primary heat exchange device 100 is a sensible heat recovery type heat exchange device. The primary heat exchange device 100 is configured with a water heater body 130, a hot water supply primary heat exchanger 110, and a bath primary heat exchanger 120. The water heater body 130, the hot water supply primary heat exchanger 110, and the bath primary heat exchanger 120 may be made of copper, which has excellent thermal conductivity, for example.

[0030] As shown in Figures 3 to 6, the can body 130 has a generally rectangular shape in plan view that is long in the left-right direction, and is formed into a cylindrical shape that is penetrated in the up-down direction. The inside of the can body 130 is divided in the left-right direction by a partition (not shown). The hot water supply primary heat exchanger 110 and the bath primary heat exchanger 120 are arranged side by side in the left-right direction within the can body 130 via this partition. In other words, the hot water supply primary heat exchanger 110 is the right part when viewed from the front, and the bath primary heat exchanger 120 is the left part when viewed from the front.

[0031] The hot water supply primary heat exchanger 110 includes a plurality of heat transfer tubes (not shown) and a plurality of connection tubes 112 connecting the heat transfer tubes. The heat transfer tubes are straight tubes with a circular cross section. A plurality of heat transfer tubes (an odd number, i.e., seven, in this embodiment) are provided. Each heat transfer tube is disposed extending in the front-rear direction with both ends penetrating the front wall and rear wall of the can body 130. Each heat transfer tube is fixed to the penetrating portion of the can body 130 by brazing or the like. Each heat transfer tube is disposed in the center of the can body 130 in the up-down direction. The heat transfer tubes are arranged in a single row side by side in the left-right direction from the partition portion toward the right wall portion. The multiple heat transfer tubes are connected in a serpentine manner up to the heat transfer tube furthest from the partition, with the rear end of the heat transfer tube closest to the partition and the rear end of the heat transfer tube adjacent to its right side connected by a connecting tube 112, and the front end of the heat transfer tube adjacent to the right of the heat transfer tube closest to the partition and the front end of the heat transfer tube adjacent to its right side connected by a connecting tube 112.

[0032] The hot water supply primary heat exchanger 110 has a hot water supply inlet opening 114 through which water from the hot water supply secondary heat exchanger 210 flows in, and a hot water supply outlet opening 115 through which heated water flows out. The hot water supply inlet opening 114 is an opening at the rear end of the heat transfer tube farthest from the partition, and is disposed at the left end of the primary heat exchange device 100 in the rear view shown in Fig. 4. The hot water supply outlet opening 115 is an opening at the front end of the heat transfer tube closest to the partition, and is disposed at a position shifted leftward from the center of the primary heat exchange device 100 in the front view shown in Fig. 3.

[0033] Water that flows in through the hot water supply inlet opening 114 from the rear side flows toward the hot water supply outlet opening 115 while meandering inside the hot water supply primary heat exchanger 110, and flows out to the front side through the hot water supply outlet opening 115. One end of the hot water supply relay pipe 15 is connected to the hot water supply inlet opening 114. The other end of the hot water supply relay pipe 15 is connected to the outlet of the hot water supply secondary heat exchanger 210, which will be described later. The hot water supply outlet opening 115 is connected to the hot water supply outlet pipe 13. When viewed from the front, the hot water supply outlet opening 115 extends diagonally downward to the right, then turns horizontally and extends to the right.

[0034] As described above, the hot water relay pipe 15 connects the hot water outlet portion 235 of the secondary heat exchange device 200 and the hot water inlet opening 114 of the hot water primary heat exchanger 110, and introduces hot water from the hot water secondary heat exchanger 210 into the hot water primary heat exchanger 110 from the hot water inlet opening 114. As shown in FIG. 6, the hot water relay pipe 15 has a downstream pipe portion 16 and an upstream pipe portion 17.

[0035] The downstream end of the downstream pipe section 16 is fixed in communication with the hot water supply inlet opening 114. The upstream end of the downstream pipe section 16 is a female side pipe 16F that is detachably connected to the upstream pipe section 17. The female side pipe 16F, which is the upstream end of the downstream pipe section 16, is formed to open forward. The downstream pipe section 16 is formed so that it extends rearward from the female side pipe 16F, then turns vertically to extend upward, and then turns horizontally to extend to the left.

[0036] The upstream end of upstream pipe section 17 is male side pipe 17M which is detachably connected to hot water supply outlet section 235 of secondary heat exchange device 200. The downstream end of upstream pipe section 17 is male side pipe 17M which is detachably connected to female side pipe 16F which is the upstream end of downstream pipe section 16. Male side pipe 17M which is the upstream end of upstream pipe section 17 opens to the left, and male side pipe 17M which is the downstream end of upstream pipe section 17 opens to the rear. Upstream pipe section 17 is formed so that it extends forward from downstream male side pipe 17M, then turns vertically and extends upward, turns diagonally backward halfway and extends diagonally backward and upward, then turns horizontally and extends to the left until it reaches upstream male side pipe 17M.

[0037] The bath primary heat exchanger 120 has a bath inlet opening 124 through which water from the bath secondary heat exchanger 220 flows in, and a bath outlet opening 125 through which heated water flows out. The bath inlet opening 124 is located to the left of the bath outlet opening 125 in the front view shown in FIG. 3. The bath outlet opening 125 is located at the right end of the primary heat exchanger 100 in the rear view shown in FIG. 4. Water flowing in from the front side through the bath inlet opening 124 flows toward the bath outlet opening 125 while meandering inside the bath primary heat exchanger 120, and flows out to the rear side through the bath outlet opening 125. One end of the bath relay pipe 40 is connected to the bath inlet opening 124. The other end of the bath relay pipe 40 is connected to the outlet of the bath secondary heat exchanger 120 described later. The bath outlet opening 125 is connected to the forward pipe 23. The supply pipe 23 bends to the right from the bath outlet opening 125 when viewed from behind, extends to the right side, then turns vertically and extends downward.

[0038] [Secondary heat exchange device] Next, the configuration of the secondary heat exchange device 200 will be described. The secondary heat exchange device 200 is a latent heat recovery type heat exchange device. As shown in Fig. 3 to Fig. 6, the secondary heat exchange device 200 is disposed above the primary heat exchange device 100. The secondary heat exchange device 200 and the primary heat exchange device 100 are connected by an exhaust hood 400 (described later) for introducing the combustion exhaust gas that has passed through the primary heat exchange device 100 into the secondary heat exchange device 200.

[0039] The secondary heat exchange device 200 is larger than the primary heat exchange device 100 in the left-right and up-down directions. The front end of the secondary heat exchange device 200 is provided to overhang forward of the front surface of the boiler body 130 of the primary heat exchange device 100. A drain outlet 238 is provided on the underside of this overhang, and a drain hose 31 is connected to the drain outlet 238.

[0040] The secondary heat exchange device 200 is configured to include a housing 230, a hot water secondary heat exchanger 210, and a bath secondary heat exchanger 220. The housing 230, the hot water secondary heat exchanger 210, and the bath secondary heat exchanger 220 may be made of stainless steel, which has excellent corrosion resistance.

[0041] The housing 230 is formed in a box shape that is long in the left-right direction. The inside of the housing 230 is divided in the left-right direction by a partition (not shown). The hot water supply secondary heat exchanger 210 and the bath secondary heat exchanger 220 are arranged side by side in the left-right direction within the housing 230 via this partition. In other words, the hot water supply secondary heat exchanger 210 is the right part when viewed from the front, and the bath secondary heat exchanger 220 is the left part when viewed from the front. Furthermore, the partition of the secondary heat exchanger 200 is located further leftward from the center of the water heater 1 compared to the partition of the primary heat exchanger 100.

[0042] The housing 230 is formed with an inlet, an outlet 233, a hot water supply inlet 234, a hot water supply outlet 235, a bath inlet 236, and a drain outlet 238 (not shown). The inlet and the outlet 233 are openings for allowing the exhaust gas to flow in and out of the secondary heat exchange device 200. The inlet is formed to open into the rear wall of the housing 230, and the outlet 233 is formed to open into the front wall of the housing 230. That is, in the secondary heat exchange device 200, the exhaust gas flows inside the housing 230 from the rear to the front.

[0043] The hot water supply inlet 234 and the hot water supply outlet 235 are openings for allowing water to flow in and out of the hot water supply secondary heat exchanger 210. The hot water supply inlet 234 and the hot water supply outlet 235 are formed on the right side wall of the housing 230, respectively. The hot water supply inlet 234 is formed in a form that opens to the right at a position near the front lower side of the right side wall of the housing 230. The hot water supply inlet 234 communicates with the inlet of the hot water supply secondary heat exchanger 210. The downstream end of the water inlet pipe 12 is detachably connected to the hot water supply inlet 234. The hot water supply outlet 235 is formed in a form that opens to the right at a position near the rear upper side of the right side wall of the housing 230. The hot water supply outlet 235 communicates with the outlet of the hot water supply secondary heat exchanger 210. The upstream end of the hot water supply relay pipe 15 is detachably connected to the hot water supply outlet 235. The downstream end of the hot water supply relay pipe 15 communicates with a hot water supply inlet opening 114 which is a rear end opening of the hot water supply primary heat exchanger 110 of the primary heat exchange device 100 .

[0044] The hot water supply secondary heat exchanger 210 is configured to have a plurality of serpentine tubes (not shown). The plurality of serpentine tubes are stacked vertically and housed in the housing 230. Each serpentine tube is arranged such that both ends are connected to the hot water supply inlet portion 234 and the hot water supply outlet portion 235, respectively. In the hot water supply secondary heat exchanger 210, water is passed in parallel through each serpentine tube to perform heat exchange.

[0045] The bath inlet 236 and the bath outlet 237 are openings for allowing water to flow in and out of the bath secondary heat exchanger 220. The bath inlet 236 and the bath outlet 237 are formed on the left side wall of the housing 230. The bath inlet 236 is formed in a position toward the lower front of the left side wall of the housing 230, opening to the left. The bath inlet 236 is connected to the inlet of the bath secondary heat exchanger 220. The downstream end of the return pipe 22 is detachably connected to the bath inlet 236. The bath outlet 237 is formed in a position toward the upper rear of the left side wall of the housing 230, opening to the left. The bath outlet 237 is connected to the outlet of the bath secondary heat exchanger 220. The upstream end of the bath relay pipe 40 is detachably connected to the bath outlet 237. The downstream end of the bath relay pipe 40 is connected to a bath inlet opening 124, which is a front end opening of the bath primary heat exchanger 120 of the primary heat exchange device 100.

[0046] The bath secondary heat exchanger 220 is composed of multiple serpentine tubes (not shown). The multiple serpentine tubes are stacked vertically and stored in the housing 230. Each serpentine tube is arranged so that both ends are connected to the bath inlet 236 and the bath outlet 237, respectively. The bath secondary heat exchanger 220 exchanges heat by passing water through each serpentine tube in parallel.

[0047] As described above, the bath relay pipe 40 connects the bath outlet section 237 of the secondary heat exchange device 200 and the bath inlet opening 124 of the bath primary heat exchanger 120, and introduces hot water from the bath secondary heat exchanger 220 into the bath primary heat exchanger 120 from the bath inlet opening 124. As shown in Figure 5, the bath relay pipe 40 has a downstream pipe section 41 and an upstream pipe section 42.

[0048] The downstream end of downstream pipe section 41 is fixed in communication with bath inlet opening 124. The upstream end of downstream pipe section 41 is female pipe 41F which is detachably connected to upstream pipe section 42. Female pipe 41F, which is the upstream end of downstream pipe section 41, opens to the left, and male pipe 41M, which is the downstream end of downstream pipe section 41, opens to the rear. Downstream pipe section 41 is formed so that it extends horizontally to the right from female pipe 41F, then turns diagonally downward and extends diagonally downward to the right, then turns horizontally and extends rearward to reach male pipe 41M.

[0049] The upstream end of upstream pipe section 42 is male side pipe 42M that is detachably connected to bath outlet section 237 of secondary heat exchange device 200. The downstream end of upstream pipe section 42 is male side pipe 42M that is detachably connected to female side pipe 41F that is the upstream end of downstream pipe section 41. Both female side pipe 42M that is the upstream end of upstream pipe section 42 and male side pipe 42M that is the downstream end of upstream pipe section 42 are formed to open to the right. Upstream pipe section 42 is formed so that it extends leftward from downstream male side pipe 42M, then turns vertically and extends upward, turns diagonally backward midway and extends diagonally backward and upward, then turns horizontally and extends rightward to reach upstream male side pipe 42M.

[0050] 3, the drain outlet 238 is formed on the lower side of the front end of the housing 230. Since the housing 230 is disposed tilted forward, the drain generated from the exhaust combustion gas from which latent heat has been recovered flows toward the front of the housing 230 and is suitably discharged from the drain outlet 238. The drain outlet 238 is formed at a position corresponding to the partition of the primary heat exchange device 100 in the left-right direction. Therefore, the drain hose 31 connected to the drain outlet 238 is provided in a form that extends downward in front of the partition.

[0051] [Burner device] The burner device 300 burns the combustion gas to generate combustion exhaust. The burner device 300 includes a burner case 330, a hot water supply burner group 310, and a bath burner group 320. The burner case 330 is provided below the can body 130 of the primary heat exchange device 100. The burner case 330 has a generally rectangular shape in a plan view that is long in the left-right direction, and is provided with an open upper end. The inside of the burner case 330 is partitioned in the left-right direction by a partition (not shown).

[0052] As conceptually shown in FIG. 2, the hot water supply burner group 310 and the bath burner group 320 are arranged side by side in the left-right direction in the burner case 330. The hot water supply burner group 310 is stored in the space on the right side in the front view of the space partitioned by the partition in the burner case 330, and the bath burner group 320 is stored in the space on the left side in the front view. As a result, the hot water supply burner group 310 is arranged below the hot water supply primary heat exchanger 110 and supplies the combustion exhaust to the hot water supply circuit 10. The bath burner group 320 is arranged below the bath primary heat exchanger 120 and supplies the combustion exhaust to the bath circuit 20. The partition of the burner device 300 is connected to the lower end of the partition of the primary heat exchange device 100. As a result, the left and right spaces in the burner case 330 are partitioned in a form that continues to the left and right spaces in the can body 130 of the primary heat exchange device 100, respectively.

[0053] As shown in Figures 1 and 2, an ignition plug 311 and a flame rod 312 are arranged in the space above the hot water supply burner group 310. Similarly, an ignition plug 321 and a flame rod 322 are arranged above the bath burner group 320. These ignition plugs 311, 321 and the flame rods 312, 322 are inserted into the burner case 330 from the front surface of the burner case 330. The ends of the ignition plugs 311, 321 and the flame rods 312, 322 each protrude forward from the front surface of the burner case 330. Wiring (not shown) is connected to the ends of the ignition plugs 311, 321 and the flame rods 312, 322, respectively.

[0054] [Exhaust hood] As shown in Fig. 1, the exhaust hood 400 is disposed between the primary heat exchanger 100 and the secondary heat exchanger 200. The exhaust hood 400 communicates the upper end opening of the can body 130 of the primary heat exchanger 100 with the inlet port in the rear wall of the housing 230 of the secondary heat exchanger 200 to form a passage for the combustion exhaust. The inside of the exhaust hood 400 is partitioned in the left and right directions by a partition (not shown). The partition of the exhaust hood 400 connects the upper end of the partition of the primary heat exchanger 100 with the rear end of the partition of the secondary heat exchanger 200 to form spaces corresponding to the hot water supply circuit 10 and the bath circuit 20, respectively.

[0055] [Pipe connection structure] As shown in Fig. 10 and Fig. 11, the pipe connection structure 2 of the water heater 1 of this embodiment includes a male side pipe M and a female side pipe F as pipes, and the male side pipe M and the female side pipe F are fixed in a connected state by a connecting part 50 shown in Fig. 12 to form the pipe connection structure 2. As shown in Fig. 5 and Fig. 6, a plurality of connecting parts 50 (six in this embodiment) are used around the secondary heat exchange device 200. The pipe connection structure 2 may be one in which the female side pipe F is fixed to the water collection part (hot water supply inlet part 234, hot water supply outlet part 235, bath inlet part 236, bath outlet part 237, etc.) of the secondary heat exchange device 200, or may be applied to a case where pipes are connected to each other (for example, a case where the upstream side pipe parts 42, 17 and the downstream side pipe parts 41, 16 are connected). In Figure 6, the connecting part 50 is not shown in order to make the hot water supply inlet opening 114 easier to see, but the connecting part 50 is also used to connect the hot water supply inlet opening 114 to the downstream end of the downstream pipe section 16.

[0056] Specifically, as shown in Fig. 5, the connecting part 50 is used in the connection between the upstream end of the bath relay pipe 40 and the bath outlet 237, the connection between the downstream end of the return pipe 22 and the bath inlet 236, and the connection between the upstream pipe 42 and the downstream pipe 41 of the bath relay pipe 40. As shown in Fig. 6, the connecting part 50 is used in the connection between the downstream end of the water inlet pipe 12 and the hot water supply inlet 234, the connection between the upstream end of the hot water supply relay pipe 15 and the hot water supply outlet 235, and the connection between the upstream pipe 17 and the downstream pipe 16 of the hot water supply relay pipe 15. In the following, the connecting part 50 will be explained using the case of connecting the male side pipe M and the female side pipe F as a representative.

[0057] The male side tube M is open to the tip side, and as shown in Figures 10 and 14, comprises a cylindrical tube body M1 and multiple annular ribs M2 formed at the tip of the tube body M1. The annular ribs M2 are provided around the entire circumference, protruding from the outer periphery of the tube body M1. In this embodiment, three annular ribs M2 are provided on the tube body M1, and an O-ring 70 is attached between the first and second annular ribs M2 from the tip in the direction in which the axis M3 of the male side tube M extends (hereinafter referred to as the "axial direction of the male side tube M"). The second and third annular ribs M2 from the tip are provided continuously in the axial direction of the male side tube M with no gaps. The portion of the tube body M1 from the third annular rib M2 to the tip side is an example of the tip of the male side tube.

[0058] The female side pipe F opens at the tip end, and as shown in Figures 10 and 14, comprises a cylindrical pipe body F1 and a fitting part F2 attached to the tip end of the pipe body F1. The fitting part F2 is provided to be connected to the tip end of the pipe body F1 in the direction in which the axis line F3 of the female side pipe F extends (hereinafter referred to as the "axial direction of the female side pipe F"). A flange part F4 extending radially outward is provided on the outer circumferential surface of the tip end of the fitting part F2 in the axial direction of the female side pipe F. The pipe body F1 is composed of the hot water relay pipe 15, the bath relay pipe 40, the heat transfer pipe of the housing 230, etc.

[0059] Additionally, the tip of the pipe body M1 of the male side pipe M fits into the fitting portion F2 of the female side pipe F, causing the multiple annular ribs M2 to enter into the area surrounded by the flange portion F4. This causes O-ring 70 to adhere closely to the outer peripheral surface of the pipe body M1 of the male side pipe M and the inner peripheral surface of the fitting portion F2 of the female side pipe F, connecting the male side pipe M and the female side pipe F in a sealed state.

[0060] The fitting portion F2 has a large diameter portion F2A into which the three annular ribs M2 fit, and a small diameter portion F2B into which a portion of the pipe body M1 that is further forward than the first annular rib M2 fits. An enlarged diameter portion F1A having a larger diameter than the pipe body F1 is formed at the forward end of the pipe body F1, and the inner peripheral surface of the enlarged diameter portion F1A is fixed to the outer peripheral surface of the small diameter portion F2B. The fitting portion F2 is an example of the forward end of a female pipe.

[0061] 7, the connecting part 50 includes a quick fastener 51 and a lock nut 60. The quick fastener 51 is fitted onto the outer circumferential surface of the male side tube M and the outer circumferential surface of the female side tube F in a mated state. The quick fastener 51 is an example of a clip, and the lock nut 60 is an example of a washer.

[0062] 7 and 8, the quick fastener 51 includes a base end side connecting portion 52 that is gate-shaped when viewed from the front, and a pair of arms 53, 53 that are arranged opposite each other and extend in a direction away from the base end side connecting portion 52. Tip end side connecting portions 54, 54 that extend in directions away from each other are provided at the tips of the arms 53, 53. The arms 53 are an example of clamping pieces.

[0063] The arms 53, 53 include first arms 53B, 53B with first arcuate portions 53A, 53A that clamp the female side pipe F, and second arms 53D, 53D with second arcuate portions 53C, 53C that are formed with a smaller radius of curvature than the first arcuate portions 53A, 53A and clamp the male side pipe M. The arms 53, 53 are configured to slightly expand and deform when attached to the male side pipe M and female side pipe F, but are configured with sufficient rigidity to not easily undergo elastic deformation. The first arms 53B are an example of a female side clamping piece, and the second arms 53D are an example of a male side clamping piece.

[0064] 7, a pair of gaps 55 are formed between the pair of first arms 53B, 53B and the pair of second arms 53D, 53D in the axial direction of male side pipe M. First arm 53B and second arm 53D are arranged with a predetermined gap 55 in the axial direction of each arcuate portion 53A, 53C such that each arcuate portion 53A, 53C is coaxial.

[0065] The tip end of the first arm 53B, 53B located on the opposite side of the base end side connecting portion 52 and the tip end of the second arm 53D, 53D located on the opposite side of the base end side connecting portion 52 are connected to each other by tip end side connecting portions 54, 54.

[0066] An introduction port 56 is formed between the tips of the pair of arms 53, 53 for introducing the male side tube M and the female side tube F between the pair of arms 53, 53. When the male side tube M and the female side tube F are inserted between the pair of arms 53, 53 through the introduction port 56, as shown in Figure 14, the large diameter portion F2A of the fitting portion F2 of the female side tube F is clamped by the pair of first arms 53B, 53B, and the tube body M1 of the male side tube M is clamped by the pair of second arms 53D, 53D.

[0067] Lock nut 60 is a plate-like member that is U-shaped in front view and includes a connecting portion 61 and a pair of arms 62, 62 extending from connecting portion 61. Lock nut 60 is formed with a guide opening 63 and an insertion portion 64 for male side tube M between arms 62, 62. The inner diameter of insertion portion 64 is formed to correspond to the outer diameter of the tip of male side tube M.

[0068] Guide opening 63 is formed at the tip of a pair of arms 62, 62, and guide opening 63 communicates with insertion portion 64. When lock nut 60 is pressed toward male side tube M with male side tube M positioned in guide opening 63, male side tube M is guided into insertion portion 64, and lock nut 60 is positioned so that the pair of arms 62, 62 and connecting portion 61 surround male side tube M by approximately half of the circumference, as shown in Figure 13.

[0069] As shown in Figure 14, lock nut 60 can be brought into close contact with flange portion F4 and annular rib M2 within flange portion F4 from the male side tube M. As shown in Figure 13, insertion portion 64 is formed with dimensions corresponding to the outer diameter of male side tube M, and as shown in Figure 14, by bringing lock nut 60 into close contact with flange portion F4, the inner edge of arm portion 62 on the insertion portion 64 side holds down annular rib M2 fitted within female side tube F from the male side tube M.

[0070] Gaps 55 in arms 53 are set to a size that allows lock nut 60 and flange portion F4 to fit in a tightly fitted state. Therefore, with lock nut 60 and flange portion F4 housed in a pair of gaps 55, quick fastener 51 is attached to male side tube M and female side tube F, thereby connecting male side tube M and female side tube F.

[0071] 8 and 9, stepped positioning portions 62A, 62A that engage with the tip end side connecting portion 54 are formed on the outer side of the tip end of each arm portion 62, 62. The positioning portion 62A is formed in a portion of the tip end of the arm portion 62 that is disposed outside the arm portion 53 from the gap 55. Each positioning portion 62A, 62A engages with each tip end side connecting portion 54, 54 when the quick fastener 51 is in its natural state. This allows the lock nut 60 to be positioned within the gap 55 with the introduction port 56 and the guide port 63 oriented in the same direction when the lock nut 60 is inserted into the pair of gaps 55 of the quick fastener 51 and temporarily assembled to the quick fastener 51.

[0072] 8, a protruding portion 62C is formed in a portion of the base end of the arm portion 62 that is disposed outside the arm portion 53 from the gap 55, protruding in a direction away from the insertion portion 64. A pair of protruding portions 62C are formed at positions that are symmetrical with respect to a virtual straight line VL that connects the centers of the insertion portion 64 and the guide port 63. The protruding portion 62C is provided at an end portion on the opposite side to the guide port 63 (inlet 56) with respect to the insertion portion 64 as the center. In this embodiment, a pair of protruding portions 62C is formed as an example, but the number of protruding portions 62C may be three or more.

[0073] At the end of the arms 62, 62 opposite the overhanging portions 62C, 62C, extension portions 62B, 62B are formed which extend in a direction away from the connecting portion 61 with the lock nut 60 positioned within the gap 55. A pair of extension portions 62B, 62B are provided on each of the pair of arms 62, 62. The extension portions 62B, 62B pass through the arms 53, 53 through the gaps 55, 55. The guide port 63 of the lock nut 60 is formed between the pair of extension portions 62B, 62B when the lock nut 60 is temporarily assembled to the quick fastener 51.

[0074] A tapered portion 62D is formed between the protruding portion 62C and the positioning portion 62A at the outer edge of the lock nut 60. As shown in Fig. 15, when the lock nut 60 is inserted into a pair of gaps 55 of the quick fastener 51, the tapered portion 62D comes into sliding contact with the tip end side connecting portion 54, causing the pair of arms 53 to open.

[0075] 7 and 11, a protrusion 65, 65 is formed at the tip of each arm portion 62, 62, protruding toward male side tube M. This protrusion 65, 65 is connected to the inner edge of extension portions 62B, 62B, and is formed in a flat plate extending in the vertical direction. Protrusion 65 functions as an insertion limiting portion that limits the amount of insertion when lock nut 60 is inserted into gap 55 of quick fastener 51.

[0076] The connecting portion 61 of the lock nut 60 has a connecting portion side extension portion 67 that extends on the opposite side to the arms 62, 62. The base end side connecting portion 52 of the quick fastener 51 has a housing portion 52A that houses the connecting portion side extension portion 67 therein when the positioning portion 62A is engaged with the tip end side connecting portion 54. The connecting portion side extension portion 67 is formed with a protruding piece 66 that protrudes toward the second arm portion 53D side within the housing portion 52A. In other words, the end of the connecting portion 61 of the lock nut 60 that is away from the arm portion 62 is formed with a protruding piece 66 that protrudes toward the male side tube M side.

[0077] The protruding piece 66 is adapted to be positioned within the accommodation portion 52A of the base end side connecting portion 52 when the lock nut 60 is temporarily assembled to the quick fastener 51. The protruding piece 66 is configured to have a dimension slightly larger than the width dimension of the narrowest portion 57 (the narrowed portion of the second arm portions 53D, 53D where the distance between the opposing surfaces is narrowest) of the pair of second arm portions 53D, 53D. Therefore, when the quick fastener 51 is in its natural state, the protruding piece 66 interferes with the narrowest portion 57 from the accommodation portion 52A side, thereby preventing the lock nut 60 from coming off the quick fastener 51 in the temporarily assembled state.

[0078] [How to install quick fasteners] In the pipe connection structure 2 of this embodiment, it is possible to attach the quick fastener 51 to the male side pipe M and the female side pipe F after inserting the lock nut 60 into the male side pipe M, but basically, the lock nut 60 is temporarily assembled to the quick fastener 51, and then the quick fastener 51 with the lock nut 60 temporarily assembled is attached to the male side pipe M and the female side pipe F.

[0079] When provisionally assembling the lock nut 60, the protruding piece 66 is inserted into the introduction port 56, and the lock nut 60 is pushed toward the base end side connecting part 52. At this time, the pair of overhanging parts 62C, 62C pass through the pair of gaps 55, 55 and overhang the pair of arm parts 53, 53. By being able to see the pair of overhanging parts 62C, 62C, it can be confirmed that the lock nut 60 is at the correct angle and in the correct insertion position, and the protruding piece 66 is in a position that allows it to enter the base end side connecting part 52. When the lock nut 60 is pushed in as it is, the tapered parts 62D, 62D slide against the tip end side connecting parts 54, 54, causing the arm parts 52, 52 of the quick fastener 51 to be slightly opened. Accordingly, the narrowest parts 57, 57 open slightly, and the protruding piece 66 passes between the narrowest parts 57, 57 without interfering with the narrowest parts 57, 57 and enters the base end side connecting part 52. Thereafter, when the tip end side connecting parts 54, 54 climb over the tapered parts 62D, 62D and drop into the step, the arms 52, 52 of the quick fastener 51 close and return to their natural state, and the positioning parts 62A, 62A engage with the tip end side connecting parts 54, 54, so that the lock nut 60 is positioned within the gaps 55, 55 with the introduction port 56 and the guide port 63 oriented in the same direction. At the same time, the narrowest parts 57, 57 return to their original positions and the protruding pieces 66 interfere with the narrowest parts 57, 57, so that the lock nut 60 is held so as not to fall off the quick fastener 51.

[0080] In this state, the male side tube M and the female side tube F are both held in position within the introduction port 56 of the quick fastener 51 and the guide port 63 of the lock nut 60, and the quick fastener 51 is pushed toward the male side tube M and the female side tube F, guiding its flange portion F4 into the gap 55. When the quick fastener 51 etc. is pushed further in this state, the arms 53, 53 are pushed apart by the male side tube M and the female side tube F. From here, the quick fastener 51 is pushed further until the female side tube F is positioned within the first arms 53B, 53B and the male side tube M is positioned within the second arms 53D, 53D, the arms 53, 53 are restored, and with the lock nut 60 and the flange portion F4 of the female side tube F inserted into the gap 55, the male side tube M is clamped by the second arms 53D, 53D, and the female side tube F is clamped by the first arms 53B, 53B. In this way, the male tube M and the female tube F are connected.

[0081] [Effects of the embodiment] In this embodiment, since the lock nut 60 having the guide port 63 is assembled in a later process, there is no need to form the annular rib with the locking disk loosely fitted as described in the background art, and productivity is excellent. Specifically, the structure connecting the male side tube M and the female side tube F is composed of the quick fastener 51 and the lock nut 60, and the male side tube M is surrounded by the pair of arms 62, 62 and the connecting portion 61 that constitute the lock nut 60, so that the lock nut 60 plays the role of the locking disk. The lock nut 60 and the flange portion F4 are accommodated in the pair of gaps 55, 55 in a state where they are in close contact with each other, and the quick fastener 51 is attached to the male side tube M and the female side tube F, thereby connecting the male side tube M and the female side tube F. Therefore, the process of loosely fitting a part equivalent to the locking disk into the male side tube M before processing the annular rib M2 can be omitted, and productivity can be improved.

[0082] Furthermore, by providing the positioning portion 62A and the protruding piece 66, the lock nut 60 can be provisionally assembled to the quick fastener 51 in a stable manner, and the assembly efficiency can be improved. Specifically, when the lock nut 60 is inserted into the gap 55 of the quick fastener 51, the lock nut 60 is positioned in the gap 55 of the quick fastener 51 with the guide port 63 and the introduction port 56 aligned in the direction of the positioning portion 62A (the portion continuing in a stepped manner from the tapered portion 62D). This prevents the lock nut 60 from being displaced relative to the quick fastener 51 when the lock nut 60 is provisionally assembled in the gap 55 of the quick fastener 51. Therefore, the lock nut 60 can be handled as a single unit in the provisionally assembled state to the quick fastener 51. Furthermore, by attaching the quick fastener 51 to the male side tube M and the female side tube F, the lock nut 60 positioned in advance can be attached to the male side tube M, and the assembly efficiency of the connecting part 50 can be improved.

[0083] For example, if the shape of the lock nut 60 is based on a disk shape like the locking disk described in the background art, when it is temporarily assembled to a quick fastener in which the arc portions 53C, 53A of the second arm portion 53D and the first arm portion 53B have a large radius of curvature, the outer edge of the lock nut 60 and the arc portions 53A, 53C of each arm portion 53B, 53D will be close to each other, and depending on the force applied to the lock nut 60, the lock nut 60 may shift to the inside of the arc portions 53A, 53C, which may impair assembly. Therefore, by providing overhanging portions 62C, 62C that protrude significantly outward from each of the arm portions 53B, 53D, it is possible to prevent the lock nut 60 from falling out of the gap 55 in the provisionally assembled state.

[0084] In addition, since the overhanging portions 62C, 62C are formed at least at two locations that are mirror-symmetrical with respect to the virtual straight line VL, it is possible to more effectively prevent the lock nut 60 from falling off the quick fastener 51. Furthermore, since the overhanging portions 62C, 62C are provided at the end of the lock nut 60 opposite the guide port 63, the overhanging portions 62C, 62C can be used as a guide when inserting the lock nut 60 into the gap 55 of the quick fastener 51, improving the ease of assembling the temporary assembly. In other words, when the overhanging portions 62C, 62C become visible during temporary assembly, the assembly angle and posture of the lock nut 60 can be adjusted so that the overhanging portions 62C, 62C protrude from the arm portions 53, 53 by the same amount, and the lock nut 60 can be easily assembled to the quick fastener 51 at the correct angle and in the correct posture, and temporary assembly can be performed smoothly without requiring a large force.

[0085] Furthermore, because the extensions 62B, 62B extend from both arms 53, 53 of the quick fastener 51 toward the side opposite the base end side connecting portion 52, and a guide port 63 is formed between the extensions 62B, 62B, the lock nut 60 can be provisionally assembled with the extensions 62B, 62B and the protruding portions 62C, 62C protruding from the quick fastener 51. Furthermore, in the provisionally assembled state, the lock nut 60 can be more stably held within the quick fastener 51, and problems such as the lock nut 60 falling off the quick fastener 51 can be prevented when attaching it to the female and male double pipes F, M.

[0086] Furthermore, when the lock nut 60 is inserted into a pair of gaps 55, 55 of the quick fastener 51, the tapered portions 62D, 62D slide against the tip side connecting portions 54, 54, opening the pair of arms 53, 53. This means that there is no need to use a large amount of force to open the pair of arms 53, 53 before inserting the lock nut 60. The pair of arms 53, 53 can be opened simply by pushing in the lock nut 60, and the lock nut 60 can be attached to the quick fastener 51 with a relatively small force.

[0087] <Other embodiments> The present invention is not limited to the embodiments described above and in the drawings. For example, the features of the above and following embodiments can be combined in any combination without contradiction. Furthermore, any feature of the above and following embodiments can be omitted unless it is clearly stated as essential. Furthermore, the above-mentioned embodiment may be modified as follows.

[0088] In the embodiment, the water heater is provided with two heat exchange devices, a primary heat exchange device and a secondary heat exchange device, but the water heater may be provided with only one heat exchange device. In this case, the exhaust hood may simply release the combustion exhaust gas that has passed through the heat exchange device into the atmosphere.

[0089] In the embodiment, a water heater configured with two circuits, a hot water supply circuit and a bath circuit, has been exemplified, but the water heater according to the present invention may be a water heater configured with only one circuit.

[0090] In the embodiment, a heat exchanger used for hot water supply has been exemplified as an example of a heat exchanger, but the heat exchanger may be used for other purposes, such as circulation for baths, central heating, etc.

[0091] In the embodiment, the lock nut 60 is illustrated as having all of the extension portion 62B, the protrusion portion 62C, the tapered portion 62D, the protrusion 65, the protruding piece 66, and the connecting portion side extension portion 67, but the lock nut may have some of these, or none of them.

[0092] It should be noted that the embodiments disclosed herein are illustrative and not restrictive in all respects. The scope of the present invention is not limited to the embodiments disclosed herein, and is intended to include all modifications within the scope indicated by the claims or within the scope equivalent to the claims. [Explanation of symbols]

[0093] 1: Water heater 2: Pipe connection structure 10: Hot water supply circuit 11: Water inlet 12: Water inlet pipe 13: Hot water outlet pipe 14: Hot water outlet 15: Hot water relay pipe 16: Downstream pipe section 16F: Female pipe 17: Upstream pipe section 17M: Male pipe 20: Bath circuit 21: Hot water inlet 22: Return pipe 23: Supply pipe 24: Hot water outlet 31: Drain hose 32: Neutralizer 33: Controller 40: Bath relay pipe 41: Downstream pipe section 41F: Female pipe 41M: Male pipe 42: Upstream pipe section 42M: Male pipe 50: Connection part 51: Quick fastener (clip) 52: Base end side connection part 52A: Storage part 53: Arm part (clamping piece) 53A: First arc part 53B: First arm part (female side clamping piece) 53C: Second arc part 53D: Second arm part (male side clamping piece) 54: Tip end side connection part 55: Gap 56: Introduction port 57: Narrowest part 60: Lock nut (washer) 61: Connection part 62: Arm part 62A: Positioning part 62B: Extension part 62C: Protruding part 62D: Tapered part 63: Guide hole 64: Insertion part 65: Protrusion 66: Protruding piece 67: Extension part on connection part side 70: O-ring 80: Water collecting portion 81: First part 82: Second part 83: Bottom portion 84: Peripheral wall portion 85: First through hole 86: Second through hole 100: Primary heat exchanger 110: Primary heat exchanger for hot water supply 112: Connection pipe 114: Inlet opening for hot water supply 115: Outlet opening for hot water supply 120: Primary heat exchanger for bath 124: Inlet opening for bath 125: Outlet opening for bath 130: Boiler body 200: Secondary heat exchanger 210: Secondary heat exchanger for hot water supply 220: Secondary heat exchanger for bath 230: Housing 231: Connection pipe 232: Housing through hole 233: Outlet 234: Inlet for hot water supply 235: Outlet for hot water supply 236: Inlet for bath 237: Outlet for bath 238: Drain outlet 300: Burner device 310: Hot water burner group 311: Spark plug 312: Flame rod 320: Bath burner group 321: Spark plug 322: Flame rod 330: Burner case 400: Exhaust hood B: Bathtub F: Female side pipe F1: Pipe body F1A: Enlarged diameter section F2: Fitting section F2A: Large diameter section F2B: Small diameter section F3: Axis line F4: Flange section M: Male side pipe M1: Pipe body M2: Annular rib M3: Axis line VL: Virtual straight line

Claims

1. a female side pipe that opens to a tip end and has a flange portion formed on an outer peripheral surface of a tip end of the female side pipe that extends radially outward; a male side tube that opens to a tip end, said male side tube having an annular rib formed at a tip end thereof, said annular rib entering an area surrounded by said flange portion when said tip end of said male side tube fits into said tip end of said female side tube; a clip fitted onto the outer circumferential surface of the male side tube and the outer circumferential surface of the female side tube in a fitted state; a washer arranged to surround the male side tube by a pair of arms and a connecting portion connecting the pair of arms together, the washer being capable of coming into close contact with the flange portion and the annular rib within the flange portion from the male side tube side, The clip includes a base end side connecting portion and a pair of clamping pieces extending from the base end side connecting portion in an opposing arrangement, the pair of clamping pieces include a pair of female side clamping pieces that clamp the female side pipe, a pair of male side clamping pieces that clamp the male side pipe, a pair of gaps formed between the pair of female side clamping pieces and the pair of male side clamping pieces in the axial direction of the male side pipe and into which the flange portion and the washer fit, and an introduction port formed between tip ends of the pair of clamping pieces for introducing the male side pipe and the female side pipe between the pair of clamping pieces, said washer has an insertion portion into which said male side tube is inserted, an inner diameter dimension of said insertion portion corresponding to an outer diameter dimension of a tip end of said male side tube, and guide openings are formed at the tips of said pair of arms which communicate with said insertion portion and guide said male side tube into said insertion portion, A piping connection structure for a water heater, in which at least one of the washer and the clip is formed with a positioning portion that positions the washer within the gap with the inlet and the guide port aligned when the washer is inserted into the pair of gaps of the clip.

2. The pipe connection structure for a water heater according to claim 1 , wherein a protruding portion is formed on a portion of the arm portion disposed outside the clamping piece from the gap, the protruding portion protruding in a direction away from the insertion portion.

3. The pipe connection structure for a water heater according to claim 2 , wherein the protruding portion is formed at least in two places symmetrically with respect to an imaginary line connecting the centers of the insertion portion and the guide port.

4. 4. The pipe connection structure for a water heater according to claim 2, wherein the protruding portion is provided at an end portion opposite the guide port with the insertion portion as a center.

5. The piping connection structure for a water heater as described in claim 4, wherein an extension portion is formed on the end of the arm portion opposite the protrusion portion, extending in a direction away from the connecting portion when the washer is positioned within the gap, a pair of the extension portions are provided on each of the pair of arms, and the guide port of the washer is formed between the pair of the extension portions when the washer is temporarily assembled to the clip.

6. The tip end of the female clamping piece and the tip end of the male clamping piece are connected to each other by a tip end side connecting part, A piping connection structure for a water heater as described in any one of claims 3 to 5, wherein a tapered portion is formed between the protrusion portion and the positioning portion at the outer edge of the washer, and when the washer is inserted into the pair of gaps of the clip, the tapered portion slides against the tip side connecting portion, thereby opening the pair of clamping pieces.

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