JP7625265B2 - Manufacturing method of water heater - Google Patents

Description

The present invention relates to a method for manufacturing a water heater.

Conventionally, latent heat recovery water heaters equipped with a primary heat exchanger and a secondary heat exchanger are known. Patent Document 1 discloses a water heater equipped with an exhaust hood whose lower end is connected to the primary heat exchanger and whose upper end is connected to the secondary heat exchanger. Combustion exhaust generated in the combustion device is led from the primary heat exchanger through the exhaust hood to the secondary heat exchanger.

JP 2021-55929 A

The hood may be divided into a first hood that is connected to the primary heat exchanger, and a second hood that connects the first hood to the secondary heat exchanger. Even in this case, each of the first hood and the second hood must be attached to the primary heat exchanger while maintaining airtightness.

The present invention has been made to solve such problems, and aims to provide a manufacturing method for a water heater that allows the exhaust hood to be properly attached to the primary heat exchanger even if the exhaust hood is constructed from multiple parts.

The method for manufacturing a water heater according to claim 1 includes a primary heat exchanger having a rectangular cylindrical peripheral wall that communicates exhaust gas from combustion generated in a combustion device from below to above, a secondary heat exchanger having a box-shaped housing and disposed above the primary heat exchanger, and an exhaust hood that communicates the primary heat exchanger and the secondary heat exchanger, the primary heat exchanger having a first extension portion extending outward from an opening at an upper end of the peripheral wall, the secondary heat exchanger having an inlet in a rear wall of the housing through which the exhaust gas from combustion flows in, the exhaust hood having a first hood and a second hood, the first hood covering the opening of the primary heat exchanger and bulging upward, and a first main body portion extending outward from a front end and left and right ends of the first main body portion and extending outward from the front, left and right ends of the first extension portion. the second hood includes a second extending portion overlapping from above the rear wall of the housing and the abutment portion, a first crimping piece portion being a plurality of crimping pieces provided on an outer edge of the second extending portion in order to crimp the first extending portion, and a contact portion extending upward, left and right from a rear end of the first main body portion to form an outlet through which the combustion exhaust gas that has passed through the peripheral wall flows out, and abutting against the rear wall of the secondary heat exchanger from behind, and the second hood includes a second main body portion that covers the outlet and the inlet, bulges rearward and has a shape with a lower end that is narrowed forward, a third extending portion that extends outward from the top and bottom ends and the left and right ends of the second main body portion and overlaps with the rear wall and the abutment portion of the housing from behind, and a third extending portion that extends rearward from a lower end of the third extending portion and is generally formed from above in the left and right direction of the rear of the first extending portion. a fourth extension portion overlapping with the first extension portion, and second crimping pieces which are a plurality of crimping pieces provided on an outer edge of the fourth extension portion in order to crimp the first extension portion, the method comprising the steps of: molding the second hood; a first direction in which a direction corresponding to a front-rear direction in a state in which the second hood is attached to the primary heat exchanger and the secondary heat exchanger is defined as a first direction; and a second direction in which a direction perpendicular to the first direction is defined as a second direction; a first step of applying a force along the first direction to a metal plate to mold the second main body portion and the third extension portion, and providing a portion corresponding to the second crimping pieces in a manner extending from an end portion on one side in the second direction to one side in the first direction; and a second step of applying a force along the first direction to a portion of the third extension portion continuous with a portion corresponding to the fourth extension portion, thereby bending a position of the third extension portion spaced a predetermined length from the portion of the third extension portion corresponding to the second crimping piece portion to the other side of the first direction, to form the fourth extension portion and the second crimping piece portion, wherein the second crimping piece portion molded at the end portion of one side of the second direction of the second hood by the first step and the second step extends downward and the second main body portion bulges rearward, and the first hood and the second hood are assembled to the primary heat exchanger and the secondary heat exchanger, and the first crimping piece portion and the second crimping piece portion are arranged around the entire circumference of the first extension portion.

The water heater is configured by dividing the exhaust hood into a first hood and a second hood. The second extension of the first hood overlaps from above with the front, left and right parts of the first extension extending outward from the opening at the upper end of the peripheral wall of the primary heat exchanger. The lower end of the second main body of the second hood has a shape that is narrowed toward the front, so that the combustion exhaust that flows out from the outlet into the inside of the second hood is easily guided upward along the shape of the lower end of the second main body to the inlet. Therefore, the efficiency of the heat exchange in the secondary heat exchange is improved. The fourth extension of the second hood overlaps from above with the entire rear part of the first extension in the left-right direction. The first crimping piece provided on the second extension and the second crimping piece provided on the fourth extension are arranged around the entire circumference of the first extension. The first crimping piece and the second crimping piece are crimped to the first extension, thereby ensuring airtightness of the joint between the first hood, the second hood and the first heat exchanger. Therefore , even if the water heater is configured with a separate exhaust hood, the exhaust hood can be appropriately attached to the primary heat exchanger.

If the process of molding the second hood includes a process of applying a force to the metal plate along a first direction and a process of applying a force to the metal plate along a second direction, a process of changing the orientation of the metal plate as the process progresses, or a press die becomes complicated, which may increase the manufacturing cost. In the manufacturing method of the water heater according to the second aspect of the present invention, in both the first and second processes of molding the second hood, the second main body portion, the third extension portion, the fourth extension portion, and the second crimping piece portion can be molded by applying a force to the metal plate along a first direction corresponding to the front-rear direction in a state in which the first hood, the second hood, the primary heat exchanger, and the secondary heat exchanger are assembled. Therefore, the manufacturing method of the water heater of the present invention can improve the productivity of the second hood having a shape that can be appropriately attached to the primary heat exchanger.

1 is a schematic diagram of the configuration of a water heater 1. FIG. 1 is a perspective view of the primary heat exchanger 5, the secondary heat exchanger 6, and the exhaust hood 10 as viewed from the right front. 2 is an exploded oblique view of the primary heat exchanger 5, the secondary heat exchanger 6, and the exhaust hood 10 as viewed from the upper right. FIG. 2 is an exploded oblique view of the primary heat exchanger 5, the secondary heat exchanger 6, and the exhaust hood 10 as viewed from the right rear. FIG. 2 is an exploded perspective view of the primary heat exchanger 5, the secondary heat exchanger 6, and the exhaust hood 10 as viewed from the lower right. FIG. 2 is a right side view of the primary heat exchanger 5, the secondary heat exchanger 6, and the exhaust hood 10. FIG. 10A to 10C are explanatory diagrams illustrating a molding process of the second hood 120.

The following describes an embodiment of the present invention. Unless otherwise specified, the device structure described below is not intended to be limiting, but is merely an explanatory example. The drawings are used to explain the technical features that may be adopted by the present invention. In the following description, the left and right, front and back, and up and down are indicated by arrows in the drawings.

The configuration of the water heater 1 will be described with reference to FIG. 1. The water heater 1 is a gas water heater of the latent heat recovery type that heats water taken in from a water pipe and supplies it to the outside, and also circulates and heats the hot water in the bathtub B. The water heater 1 mainly comprises a fan 3, a combustion device 4, a primary heat exchanger 5, and a secondary heat exchanger 6 inside an inner body 2 housed in a housing (not shown). The fan 3 is provided at the bottom of the inner body 2. The fan 3 supplies air to the inside of the inner body 2.

The combustion device 4 is provided above the fan 3 in the inner body 2. The inside of the combustion device 4 is divided into two chambers by a partition member 40. One chamber is equipped with a hot water supply burner group 41 consisting of multiple gas burners, an ignition plug 411, and a flame rod 412. The other chamber is equipped with a bath burner group 42 consisting of multiple gas burners, an ignition plug 421, and a flame rod 422. The water heater 1 is equipped with a gas inlet 11 to which an external gas pipe is connected. The gas inlet 11 is connected to a gas distribution unit 12. The gas distribution unit 12 is equipped with a gas pipe through which gas supplied from the gas inlet 11 flows, and various solenoid valves and distribution pipes for distributing and supplying the gas flowing through the gas pipe to the hot water supply burner group 41 and the bath burner group 42. The hot water supply burner group 41 ejects a mixture of gas supplied from the gas distribution unit 12 and air supplied from the fan 3. The mixture burns in response to the ignition plug 411 igniting the mixture. The bath burner group 42 ejects a mixture of gas supplied from the gas distribution unit 12 and air supplied from the fan 3. The mixture is burned in response to the ignition of the mixture by the spark plug 421.

The primary heat exchanger 5 is provided above the combustion device 4 in the inner body 2. The primary heat exchanger 5 communicates the combustion exhaust generated by the combustion of the air-fuel mixture in the combustion device 4 from below to above. The inside of the primary heat exchanger 5 is divided into two chambers by a partition member 50. A first heat transfer tube for hot water supply 53 is arranged inside one of the chambers. A first heat transfer tube for bath 54 is arranged inside the other chamber. The first heat transfer tube for hot water supply 53 and the first heat transfer tube for bath 54 are water tubes for recovering sensible heat from the combustion exhaust that communicates with the primary heat exchanger 5. In the primary heat exchanger 5, heat exchange is performed in which the thermal energy of the sensible heat contained in the combustion exhaust is transferred to the water flowing through the first heat transfer tube for hot water supply 53 and the first heat transfer tube for bath 54.

The secondary heat exchanger 6 is provided above the primary heat exchanger 5 and is connected to the primary heat exchanger 5 via the exhaust hood 10. The combustion exhaust gas that has passed through the primary heat exchanger 5 enters the secondary heat exchanger 6 via the exhaust hood 10. The inside of the secondary heat exchanger 6 is divided into two chambers. The second heat transfer tube 63 for hot water supply is disposed inside one chamber. The second heat transfer tube 64 for bath is disposed inside the other chamber. The second heat transfer tube 63 for hot water supply and the second heat transfer tube 64 for bath are water tubes for recovering latent heat from the combustion exhaust gas that communicates with the secondary heat exchanger 6. In the secondary heat exchanger 6, heat exchange is performed in which the thermal energy of the latent heat of the combustion exhaust gas is transferred to the water flowing through the second heat transfer tube 63 for hot water supply and the second heat transfer tube 64 for bath. The combustion exhaust gas after the latent heat is recovered is exhausted from the exhaust pipe 69 that communicates with the exhaust port 68.

The water heater 1 includes a water inlet 13, a water supply section 14, a water supply pipe 71, a relay pipe 81, a water outlet pipe 91, a bypass pipe 101, a water outlet section 15, and a water outlet 16. An external water pipe is connected to the water inlet 13. The water inlet 13 is connected to the water supply section 14. The water supply section 14 includes a motor for flow control, a water flow sensor, an inlet water temperature sensor, and the like. The water supply pipe 71 is a water pipe that connects the water supply section 14 and the second heat transfer pipe 63 for hot water supply. The relay pipe 81 is a water pipe that connects the second heat transfer pipe 63 for hot water supply and the first heat transfer pipe 53 for hot water supply. The water outlet pipe 91 is a water pipe that connects the first heat transfer pipe 53 for hot water supply and the water outlet section 15. The bypass pipe 101 is a water pipe that connects the water supply section 14 and the water outlet pipe 91 without passing through the primary heat exchanger 5 and the secondary heat exchanger 6. The water outlet 15 is equipped with a hot water temperature sensor, etc. The water outlet 16 is connected to the water outlet 15, and supplies hot water at an appropriate temperature, which is a mixture of the hot water flowing through the water outlet pipe 91 and the water supplied from the bypass pipe 101, to the outside.

The water heater 1 is equipped with a hot water inlet 721, a pump 72, a water supply pipe 722, a relay pipe 82, a hot water outlet pipe 92, and a hot water outlet 921. The hot water inlet 721 is connected to an external bathtub B, and draws in hot water from inside the bathtub B in response to the operation of the pump 72. The water supply pipe 722 is a water pipe that connects the pump 72 to the second bath heat transfer pipe 64. The relay pipe 82 is a water pipe that connects the second bath heat transfer pipe 64 to the first bath heat transfer pipe 54. The hot water outlet pipe 92 is a water pipe that connects the first bath heat transfer pipe 54 to the hot water outlet 921. The hot water outlet 921 is connected to the bathtub B, and discharges hot water that is heated in the primary heat exchanger 5 and the secondary heat exchanger 6 and flows through the hot water outlet pipe 92 into the bathtub B.

The water heater 1 also includes drain pipes 661, 662 and a neutralizer 66. The drain pipe 6661 connects the drain outlet 663 provided at the bottom of the secondary heat exchanger 6 to the neutralizer 66. The drain generated by the recovery of latent heat in the secondary heat exchanger 6 is discharged from the drain outlet 663 to the outside of the secondary heat exchanger 6 and sent to the neutralizer 66 via the drain pipe 661. The drain sent to the neutralizer 66 is neutralized in the neutralizer 66 and is discharged to the outside of the water heater 1 via the drain pipe 662.

2 to 4, the configurations of the primary heat exchanger 5, the secondary heat exchanger 6, and the exhaust hood 10 will be described. The primary heat exchanger 5 has a rectangular cylindrical peripheral wall 51 extending in the vertical direction. The peripheral wall 51 is made of a metal with excellent heat transfer properties and constitutes a part of the inner body 2. The peripheral wall 51 has a front wall 511, a rear wall 512, a left wall 513, and a right wall 514. The lower ends of the front wall 511, the rear wall 512, the left wall 513, and the right wall 514 each form a rectangular opening 517 at the lower part of the peripheral wall 51. The peripheral wall 51 is connected to an opening at the upper part of the square box-shaped combustion device 4 at an edge portion 518 extending outward from the opening 517. The peripheral wall 51 communicates the combustion exhaust generated by the combustion of the mixture in the combustion device 4 from below to above. Inside the peripheral wall 51, the first hot water heat transfer pipe 53 and the first bath heat transfer pipe 54 shown in FIG. 1 are arranged so as to move back and forth multiple times in the front-to-rear direction. Of the multiple through holes provided in the front wall 511 and the rear wall 512, the first hot water heat transfer pipe 53 is arranged in the seven through holes on the right side, and the first bath heat transfer pipe 54 is arranged in the three through holes on the left side. In order to clearly show the configuration of the peripheral wall 51, the first hot water heat transfer pipe 53 and the first bath heat transfer pipe 54 are not shown in FIG. 2 to FIG. 5.

3 and 4, the upper ends of the front wall 511, the rear wall 512, the left wall 513, and the right wall 514 each form a rectangular opening 515 at the top of the peripheral wall 51. The combustion exhaust after sensible heat is recovered in the primary heat exchanger 5 flows upward from the opening 515. A first extension portion 55 extending outward from the opening 515 is provided on the periphery of the opening 515. The first extension portion 55 includes extension portions 551, 552, 553, and 554. The extension portion 551 extends approximately horizontally forward from the upper end of the front wall 511. The extension portion 552 extends approximately horizontally rearward from the upper end of the rear wall 512. The extension portion 553 extends approximately horizontally from the upper end of the left wall 513 toward the left. The extension portion 554 extends roughly horizontally to the right from the upper end of the right wall 514.

The secondary heat exchanger 6 comprises a metal housing 61 with excellent heat transfer properties, and constitutes a part of the inner body 2. The housing 61 comprises an upper wall 611, a lower wall 612, a left wall 613, a right wall 614, a front wall 615, and a rear wall 616 shown in FIG. 4. The widths in the left-right direction of the upper wall 611, the lower wall 612, the front wall 615, and the rear wall 616 are approximately the same as the width of the primary heat exchanger 5 in the left-right direction. The widths in the front-rear direction of the upper wall 611, the lower wall 612, the left wall 613, and the right wall 614 are longer than the width of the primary heat exchanger 5 in the front-rear direction. The rear wall 616 is positioned approximately at the same position as the rear of the combustion device 4, and the front of the housing 61 is positioned to protrude forward from the front of the primary heat exchanger 5.

As shown in FIG. 4, the inside of the housing 61 is divided into two chambers, and in the right chamber, the second hot water heat transfer pipe 63 is arranged so as to move back and forth in the left-right direction multiple times. In the left chamber, the second bath heat transfer pipe 64 is arranged so as to move back and forth in the left-right direction multiple times. A connection part 631 is provided in the front lower part of the right wall 614, where the upstream end of the second hot water heat transfer pipe 63 is arranged. A connection part 632 is provided in the rear upper part of the right wall 614, where the downstream end of the second hot water heat transfer pipe 63 is arranged. Although not shown, the left wall 613 is provided with connections where the upstream and downstream ends of the second bath heat transfer pipe 64 are respectively arranged.

Inlets 617, 618, which are rectangular openings for allowing the combustion exhaust gas to flow into the inside of the housing 61, are provided side by side in the center of the rear wall 616. The right inlet 617 is provided in correspondence with the room on the side where the second hot water heat transfer pipe 63 is arranged. The left inlet 618 is provided in correspondence with the room on the side where the second bath heat transfer pipe 64 is arranged. Above the inlets 617, 618, screw holes 11D, 11E, 11F, 11G are provided side by side from the left.

As shown in FIG. 2, a rectangular exhaust port 68 extending in the left-right direction is provided in the center of the front wall 615. The exhaust gas from the combustion after the latent heat is recovered in the secondary heat exchanger 6 is exhausted from the exhaust port 68. An exhaust pipe 69 is fixed to the front side of the front wall 615 so as to communicate with the exhaust port 68. The exhaust pipe 69 exhausts the exhaust gas from the exhaust port 68 to the outside of the water heater 1.

The exhaust hood 10 is a member that covers the opening 515 in the peripheral wall 51 of the primary heat exchanger 5 from above and connects the primary heat exchanger 5 and the secondary heat exchanger 6, and constitutes part of the inner body 2. The exhaust hood 10 comprises a first hood 110 and a second hood 120. The first hood 110 is made of metal with excellent heat conductivity and constitutes the front part of the exhaust hood 10. The second hood 120 constitutes the rear part of the exhaust hood 10.

As shown in Figures 3 and 4, the first hood 110 includes a first main body portion 111, a second extension portion 112, a first crimping piece portion 115, an abutment portion 116, and an abutment frame 117. The first main body portion 111 has a shape that bulges upward. The first main body portion 111 covers the opening 515 in the peripheral wall 51 of the primary heat exchanger 5 from above. The second extension portion 112 is a portion that extends outwardly approximately horizontally from the front end, left end, and right end of the first main body portion 111.

A number of crimping pieces 113 are provided at a predetermined interval on the outer edge of the second extending portion 112. Each of the crimping pieces 113 extends downward and has a through hole in its center into which a crimping pin (not shown) is inserted. Hereinafter, the set of the multiple crimping pieces 113 provided on the outer edge of the second extending portion 112 is referred to as the first crimping piece portion 115.

3 and 4, the abutment portion 116 is a portion that extends from the rear end of the first body portion 111 upward, leftward, and rightward in a substantially vertical manner. As shown in FIG. 4, the abutment portion 116 extends at a position forward of the rear wall 512 of the peripheral wall 51 of the primary heat exchanger 5. As shown in FIG. 4, the portion where the abutment portion 116 and the first body portion 111 are continuous forms an outlet 114, which is an opening that opens in an arch shape toward the rear. The outlet 114 causes the combustion exhaust gas guided into the second extension portion 112 and the inside of the first body portion 111 to flow out to the rear of the first hood 110. The front surface of the abutment portion 116 abuts against the rear wall 616 of the secondary heat exchanger 6 from the rear. On the left part of the abutment portion 116, screw holes 11A, 11B, and 11C are provided in a row from the bottom. On the right side of the abutment portion 116, screw holes 11H, 11I, and 11J are provided in a row from top to bottom.

The partition member 50 is attached at a position slightly to the left of the center of the abutment portion 116. The partition member 50 is a plate-shaped member that divides the interior of the exhaust hood 10 into two chambers. The chamber on the left side of the partition member 50 corresponds to the chamber located above the area in the primary heat exchanger 5 where the first bath heat transfer pipe 54 is located, and the chamber on the right side of the partition member 50 corresponds to the chamber located above the area in the primary heat exchanger 5 where the first hot water heat transfer pipe 53 is located.

The abutment frame 117 is a portion that extends rearward substantially horizontally at the same vertical position as the second extension portion 112, rearward of the abutment portion 116. The shape of the abutment frame 117 corresponds to the shape of the extension portion 552 of the first extension portion 55.

3 and 4, the second hood 120 has a rectangular shape that is long in the left-right direction when viewed from the rear. The second hood 120 includes a second main body portion 121, a third extension portion 122, a fourth extension portion 123, and a second crimping piece portion 126. The second main body portion 121 has a shape that bulges rearward and constitutes the main body portion of the second hood 120. The second main body portion 121 has a shape that bulges furthest rearward at its center and is narrowed forward as it moves outward from the center. The third extension portion 122 is a surface portion that extends substantially vertically outward from the upper end, lower end, left end, and right end of the second main body portion 121 and constitutes the periphery of the second main body portion 121. The upper end portion of the third extension portion 122 is slightly folded back rearward to reinforce the upper portion of the third extension portion 122. Screw holes 12A, 12B, and 12C are provided in a row from bottom to top on the left side of the third extension portion 122. Screw holes 12D, 12E, 12F, and 12G are provided in a row from left to top on the top side of the third extension portion 122. Screw holes 12H, 12I, and 12J are provided in a row from top to bottom on the right side of the third extension portion 122.

As shown in FIG. 4, the fourth extending portion 123 is a portion that extends rearward substantially horizontally from the lower end of the third extending portion 122. The fourth extending portion 123 extends across the entire left-right direction at the bottom of the second hood 120. A plurality of crimping pieces 125 are provided at a predetermined interval on the outer edge of the fourth extending portion 123. Each of the crimping pieces 125 extends downward and has a through hole in its center through which a crimping pin (not shown) is inserted. Hereinafter, the collection of the plurality of crimping pieces 125 provided on the outer edge of the fourth extending portion 123 is referred to as the second crimping piece 126.

With reference to Figures 3 to 5, an example of a method of assembling the primary heat exchanger 5, the exhaust hood 10, and the secondary heat exchanger 6 will be described. As shown in Figures 3 and 4, the first hood 110 of the exhaust hood 10 is assembled to the primary heat exchanger 5. The second extension portion 112 of the first hood 110 is assembled so as to overlap from above with the first extension portion 55 provided on the periphery of the opening 515 of the peripheral wall 51 of the primary heat exchanger 5. The front portion 13A of the second extension portion 112 extending forward from the front end of the first main body portion 111 overlaps from above with the extension portion 551 of the first extension portion 55. The left portion 13B of the second extension portion 112 extending leftward from the left end of the first main body portion 111 overlaps from above with the extension portion 552 of the first extension portion 55. The right portion 13C of the second extension portion 112 extending rightward from the right end of the first main body portion 111 overlaps the extension portion 553 of the first extension portion 55 from above. In addition, the abutment frame 117 overlaps the extension portion 553 of the first extension portion 55 of the peripheral wall 51 of the primary heat exchanger 5 from above. This positions the second extension portion 112 and the abutment frame 117 of the first hood 110 relative to the first extension portion 55 of the peripheral wall 51. In addition, the first main body portion 111 of the first hood 110 covers the opening 515 of the peripheral wall 51 from above.

The center of the front portion 13A is provided with fixing portions 118, 119 for screwing and fixing a support member 67 for supporting the front portion of the secondary heat exchanger 6 against the first hood 110. The support member 67 is an L-shaped plate member in a side view, and includes a first portion 671 extending in the vertical direction and a second portion 672 extending forward from the upper end of the first portion 671.

The first portion 671 of the support member 67 abuts against the front portion of the bottom wall 612 of the housing 61 from below. A screw hole 673 on the left side of the first portion 671 is screwed into the fixing portion 118. A screw hole 674 on the right side of the first portion 671 is screwed into the fixing portion 119. This supports the front portion of the secondary heat exchanger 6 against the first hood 110. In addition, the front surface of the abutment portion 116 of the first hood 110 abuts against the rear wall 616 of the secondary heat exchanger 6 from behind, so that the abutment portion 116 and the rear wall 616 of the secondary heat exchanger 6 are arranged side by side at approximately the same position in the front-to-rear direction.

In this state, the second hood 120 is assembled to the rear of the first hood 110 and the secondary heat exchanger 6. The fourth extension portion 123 of the second hood 120 is overlapped from above with the extension portion 552 of the first extension portion 55 of the primary heat exchanger 5 via the abutment frame 117 of the first hood 110. The fourth extension portion 123 is overlapped with the extension portion 552 so as to cover the entire left-right direction of the extension portion 552. The multiple crimping pieces 125 provided on the outer edge of the fourth extension portion 123 are arranged along the outer edge of the extension portion 552.

The upper part of the third extension part 122 overlaps the rear wall 616 of the housing 61 of the secondary heat exchanger 6 via a gasket (not shown). The lower part of the third extension part 122 overlaps the abutment part 116 of the first hood 110 via a gasket (not shown) from the rear. The screw holes 12A, 12B, 12C on the left side of the third extension part 122 are respectively overlapped with the screw holes 11A, 11B, 11C on the left side of the abutment part 116 and are screwed together. The screw holes 12D, 12E, 12F, 12G on the upper part of the third extension part 122 are respectively overlapped with the screw holes 11D, 11E, 11F, 11G on the upper part of the rear wall 616 of the housing 61 and are screwed together. The screw holes 12H, 12I, and 12J on the right side of the third extension 122 are aligned with the screw holes 11H, 11I, and 11J on the right side of the abutment 116, respectively, and are screwed together. This results in the second body 121 of the second hood 120 covering the outlet 114 of the first hood 110 and the inlets 617 and 618 of the rear wall 616 of the housing 61 from behind.

In this state, as shown in FIG. 5, the multiple crimping pieces 113 provided on the outer edge of the front portion 13A of the second extension portion 112 of the first hood 110 are arranged along the outer edge of the extension portion 551 of the first extension portion 55 of the peripheral wall 51 of the primary heat exchanger 5. The multiple crimping pieces 113 provided on the outer edge of the left portion 13B shown in FIG. 3 are arranged along the outer edge of the extension portion 553 of the first extension portion 55 shown in FIGS. 3 and 4. The multiple crimping pieces 113 provided on the outer edge of the right portion 13C are arranged along the outer edge of the extension portion 554 of the first extension portion 55. In other words, the first crimping pieces 115 are arranged around the extension portions 551, 553, and 554 of the first extension portion 55 of the peripheral wall 51 of the primary heat exchanger 5. In addition, a second crimping piece portion 126 consisting of multiple crimping pieces 125 provided on the outer edge of the fourth extension portion 123 of the second hood 120 is arranged along the outer edge of the extension portion 552 of the first extension portion 55 shown in Figures 3 and 4. In other words, when the first hood 110 and the second hood 120 are assembled to the primary heat exchanger 5 and the secondary heat exchanger 6, the first crimping piece portion 115 and the second crimping piece portion 126 are arranged around the entire circumference of the first extension portion 55 of the peripheral wall 51 of the primary heat exchanger 5.

Each of the multiple crimping pieces 113 constituting the first crimping piece portion 115 is bent inward along each of the extension portions 551, 553, and 554, and is crimped to each of the extension portions 551, 553, and 554. In addition, the multiple crimping pieces 125 constituting the second crimping piece portion 126 are also bent inward along the outer edge of the extension portion 552, and are crimped to the extension portion 552. As a result, the second extension portion 112 of the first hood 110 and the fourth extension portion 123 of the second hood 120 are firmly joined to the first extension portion 55 of the peripheral wall 51 of the primary heat exchanger 5, and the airtightness between the first hood 110, the second hood 120, and the primary heat exchanger 5 is ensured. That is, even if the exhaust hood 10 of the water heater 1 is constructed by dividing it into two components, the first hood 110 and the second hood 120, the first hood 110 and the second hood 120 can be appropriately attached to the primary heat exchanger 5.

With reference to FIG. 6, the manner in which the combustion exhaust gas passes through the primary heat exchanger 5 and the exhaust hood 10 and is guided to the secondary heat exchanger 6 will be described. As shown by the arrow Y1, the combustion exhaust gas generated in the combustion device 4 flows from the bottom to the top inside the peripheral wall 51 of the primary heat exchanger 5, and flows out from the opening 515 shown in FIG. 3 and FIG. 5 into the inside of the first hood 110. The combustion exhaust gas that flows into the inside of the first hood 110 flows out from the outlet 114 shown in FIG. 4 and FIG. 5 and flows into the inside of the second hood 120. The lower part of the second main body part 121 of the second hood 120 has a shape that is narrowed forward. Therefore, the combustion exhaust gas that flows into the inside of the second hood 120 flows upward along the shape of the lower part of the second main body part 121. The combustion exhaust gas that flows toward the upper part of the second main body part 121 flows into the inside of the secondary heat exchanger 6 from the inlets 617, 618 of the rear wall 616 shown in FIG. 4 of the housing 61 of the secondary heat exchanger 6. That is, the exhaust combustion air that flows from the first hood 110 into the second hood 120 flows smoothly upward inside the second main body portion 121 of the second hood 120 along the narrowed shape of the lower part of the second main body portion 121 of the second hood 120, so pressure loss is unlikely to occur in the exhaust combustion air inside the second hood 120. Therefore, the exhaust combustion air can move inside the second hood 120 while retaining sufficient thermal energy and flow into the secondary heat exchanger 6. Therefore, the water heater 1 can improve the efficiency of heat exchange in the secondary heat exchanger 6.

The molding process of the second hood 120 will be described with reference to FIG. 7. The second hood 120 is molded by pressing the metal plate 100 using a press machine to which a die is fixed. The die used in this molding process includes an upper die 210 and a lower die 220. The upper die 210 is fixed to a slide that moves up and down in the press machine. The lower die 220 is fixed to a bolster whose position in the first direction is fixed in the press machine. The upper die 210 includes a split die 21A that can move independently from one side to the other in the first direction relative to the upper die 210. The lower die 220 includes a split die 22A that can move independently from one side to the other in the first direction relative to the lower die 220. Note that the first direction in this molding process is the up-down direction, with one side of the first direction corresponding to the upper side and the other side of the first direction corresponding to the lower side. The first direction corresponds to the front-rear direction when the second hood 120, which is a finished product produced by the molding process, is attached to the primary heat exchanger 5 and the secondary heat exchanger 6. One side of the first direction corresponds to the front side when the second hood 120 is attached to the primary heat exchanger 5 and the secondary heat exchanger 6, and the other side of the first direction corresponds to the rear side when the second hood 120 is attached to the primary heat exchanger 5 and the secondary heat exchanger 6.

The direction perpendicular to the first direction is the second direction. The second direction in this molding process is the left-right direction, with one side of the second direction corresponding to the left side and the other side of the first direction corresponding to the right side. The second direction corresponds to the up-down direction in the state in which the second hood 120, which is the finished product of the molding process, is assembled to the primary heat exchanger 5 and the secondary heat exchanger 6. One side of the second direction corresponds to the lower side in the state in which the second hood 120 is assembled to the primary heat exchanger 5 and the secondary heat exchanger 6, and the other side of the first direction corresponds to the upper side in the state in which the second hood 120 is assembled to the primary heat exchanger 5 and the secondary heat exchanger 6. In order to explain the shape molded in this molding process, the sheet metal 100, the intermediate product 109 being molded, the finished second hood 120, the upper mold 210, and the lower mold 220 are each shown in a schematic cross-sectional view in FIG. 7.

When the molding process of the second hood 120 is started, the worker prepares the sheet metal 100 shown in FIG. 7 (1) and inserts the sheet metal 100 between the upper die 210 and the lower die 220 as shown in FIG. 7 (2). The upper die 210 has parts 21B, 21C, 21D, 21E, and 21F as parts of the other side surface in the first direction. Part 21B is a substantially horizontal surface portion that is located at the other position in the first direction of the upper die 210. Part 21B is provided to mold the folded-back portion of the upper part of the third extension part 122 of the second hood 120 by the step with part 21C. Part 21C is a substantially horizontal surface portion that is adjacent to one side of part 21B in the second direction and is located on one side of part 21B in the first direction. Part 21C is a part that corresponds to the upper shape of the third extension part 122 of the second hood 120. The portion 21D is adjacent to one side of the portion 21C in the second direction. The portion 21D is a portion that protrudes toward the other side of the first direction in response to the bulging shape of the second main body portion 121 of the second hood 120. The portion 21E is adjacent to one side of the portion 21D in the second direction and is a surface portion that extends substantially horizontally continuous with the upper end portion of the portion 21D. The split mold 21A is disposed in a portion of the portion 21E that is slightly spaced from the portion 21D in one side of the second direction. When the molding process of the second hood 120 is started, the lower surface of the split mold 21A is disposed side by side with the portion 21E at the same position in the first direction. The portion 21C and the portion 21E are disposed at the same position in the first direction. The portion 21F is adjacent to one side of the portion 21E in the second direction and is a substantially horizontal surface portion that is disposed on one side of the portion 21E in the first direction. Part 21F is provided to mold part 128, which corresponds to the second crimping piece of intermediate product 109, which will be described later.

The lower mold 220 has parts 22B, 22C, 22D, 22E, and 22F as parts of one side surface in the first direction. Part 22B is a part that faces part 21B of the upper mold 210. Part 22B is a substantially horizontal surface portion that is located at the other position of the lower mold 220 in the first direction. Part 22C is a part that faces part 21C of the upper mold 210. Part 22C is a substantially horizontal surface portion that is adjacent to one side of part 22B in the second direction and is located on one side of part 22B in the first direction. Part 22D is a part that faces part 21D of the upper mold 210. Part 22D is adjacent to one side of part 22C in the second direction. Part 22D is a part that is recessed to the other side of the first direction in response to the bulging shape of the second main body portion 121 of the second hood 120. Part 22E is a part facing part 21E of upper mold 210. Part 22E is adjacent to one side of part 22D in the second direction and is a surface portion that extends approximately horizontally continuous with the upper end of part 22D. Split mold 22A is placed on part 22E. When the molding process of second hood 120 is started, the upper surface of split mold 22A constitutes part 22E. When the molding process of second hood 120 is started, part 22C and part 22E are placed at the same position in the first direction. Part 22F is a part facing part 21F of upper mold 210. Part 22F is adjacent to one side of part 22E in the second direction and extends approximately horizontally in one side of the first direction further than part 22E.

In the next step, as shown in FIG. 7 (3), the worker moves the upper die 210 from one side to the other in the first direction to bring it close to the lower die 220, and applies a force F from one side to the other in the first direction to the metal sheet 100. As a result, the metal sheet 100 is molded to match the shapes of the upper die 210 and the lower die 220, and an intermediate product 109 is obtained. The intermediate product 109 includes a third extension portion 122, a second main body portion 121, an intermediate portion 127, and a portion 128. The third extension portion 122 in the intermediate product 109 is formed by pressing the metal sheet 100 between the portion 22C of the lower die 220 and the portion 21C of the upper die 210. The third extension portion 122 in the intermediate product 109 corresponds to the portion of the third extension portion 122 in the second hood 120 of the finished product that extends outward from the upper end, left end, and right end of the second main body portion 121. The second body portion 121 is formed by pressing the metal plate 100 between the portion 22D of the lower die 220 and the portion 21D of the upper die 210.

The intermediate portion 127 is formed by pressing the metal sheet 100 between the portion 22E of the lower mold 220 and the portion 21E of the upper mold 210. The intermediate portion 127 is a portion of the third extension portion 122 in the second hood 120 of the finished product, including a portion extending outward from the lower end of the second main body portion 121 and a portion corresponding to the fourth extension portion 123. In the process shown in FIG. 7 (3), the intermediate portion 127 extends approximately horizontally at the same position in the first direction as the third extension portion 122. The portion 128 is formed by pressing the end of the metal sheet 100 arranged across the portion 22E and the portion 22F of the lower mold 220 by the portion 21E and the portion 22F of the upper mold 210. The portion 128 is formed in a state where it is bent perpendicularly to the intermediate portion 127 at the end of the intermediate portion 127 opposite to the second main body portion 121. Part 128 is the part that constitutes the second crimping piece 126 in the finished second hood 120.

In the next step, as shown in FIG. 7(4), the worker moves the split mold 21A built into the upper mold 210 from one side to the other in the first direction to protrude from the portion 21E. The worker also moves the split mold 22A built into the lower mold 220 from one side to the other in the first direction to collapse the portion 22E. A force F is applied from one side to the other in the first direction to the portion of the intermediate portion 127 adjacent to the portion 128. As a result, at a position of the intermediate portion 127 spaced a predetermined length from the portion 128 on the other side of the second direction, the portion of the intermediate portion 127 continuing to the portion 128 is bent perpendicularly to the portion of the intermediate portion 127 continuing to the second main body portion 121. The portion of the intermediate portion 127 adjacent to the second main body portion 121 forms the portion of the third extension portion 122 in the second hood 120 of the finished product that extends outward from the lower end of the second main body portion 121. The portion of the intermediate portion 127 adjacent to the portion 128 forms the fourth extension portion 123. The portion 128 extends perpendicular to the fourth extension portion 123 at the outer edge of the formed fourth extension portion 123, forming the second crimping piece portion 126. Thus, the second hood 120 is completed as shown in FIG. 7 (5).

If the process of molding a press-formed product includes a process of applying a force to the metal sheet along a first direction and a process of applying a force to the metal sheet along a second direction, a process of changing the orientation of the metal sheet relative to the mold is required as the process progresses. The molding process of the second hood 120 can mold the finished second hood 120 via the intermediate product 109 by applying a force F to the metal sheet 100 along the first direction without applying a force to the metal sheet 100 along the second direction using the upper mold 210 and the lower mold 220. In other words, the molding process of the second hood 120 can improve the productivity of the second hood 120.

As described above, the water heater 1 includes an exhaust hood 10 that connects the primary heat exchanger 5 and the secondary heat exchanger 6. The exhaust hood 10 is divided into a first hood 110 and a second hood 120. The second extension 112 of the first hood 110 overlaps from above with the extensions 551, 553, and 554 that constitute the front, left, and right parts of the first extension 55 that extends outward from the opening 515 at the upper end of the peripheral wall 51 of the primary heat exchanger 5. Since the lower end of the second main body 121 of the second hood 120 has a shape that is narrowed toward the front, the combustion exhaust that flows out from the outlet 114 of the first hood 110 to the inside of the second hood 120 moves upward inside the second main body 121 along the shape of the lower end of the second main body 121. Therefore, the combustion exhaust inside the second main body 121 is efficiently guided to the inlets 617 and 618 of the secondary heat exchanger 6. The fourth extending portion 123 of the second hood 120 is overlapped above the extending portion 552 so as to cover the entire extending portion 552 constituting the rear portion of the first extending portion 55 in the left-right direction. As a result, the first crimping piece 115 of the first hood 110 and the second crimping piece 126 of the second hood 120 are arranged around the entire circumference of the first extending portion 55 of the peripheral wall 51 of the primary heat exchanger 5. Each of the multiple crimping pieces 113 constituting the first crimping piece 115 is crimped to the extending portions 551, 552, and 553. The multiple crimping pieces 125 constituting the second crimping piece 126 are crimped to the extending portion 551. This firmly bonds the second extension 112 of the first hood 110 and the fourth extension 123 of the second hood 120 to the first extension 55 of the peripheral wall 51 of the primary heat exchanger 5, ensuring airtightness between the first hood 110 and the second hood 120 and the primary heat exchanger 5. In this way, even if the exhaust hood 10 of the water heater 1 is configured to be divided into the first hood 110 and the second hood 120, the exhaust hood 10 can be appropriately attached to the primary heat exchanger 5.

When the molding process of the parts of the water heater 1 such as the second hood 120 includes a process of applying a force to the sheet metal along a first direction and a process of applying a force along a second direction perpendicular to the first direction, it becomes necessary to change the orientation of the sheet metal as the process progresses. In addition, the manufacturing cost of the parts may increase due to the complicated shape of the mold. The molding process of the second hood 120 of the water heater 1 includes a first process of applying a force F from one side to the other side in the first direction to the sheet metal 100 to mold an intermediate product 109 including a third extension portion 122, a second main body portion 121, an intermediate portion 127, and a portion 128. In addition, in the second process, a force F from one side to the other side in the first direction is applied to the intermediate portion 127 to bend the intermediate portion 127 vertically at a position spaced a predetermined length from the portion 128 to the other side in the second direction. In response to this, a portion of the third extension portion 122 extending outward from the lower end of the second main body portion 121 and a fourth extension portion 123 are formed. As a result, portion 128 extends perpendicular to the fourth extension 123 at the outer edge of the formed fourth extension 123, forming a second crimping piece 126. In either process, force F is applied to the metal plate 100 and intermediate product 109 in the first direction from one side to the other, improving the productivity of the second part 120.

In this embodiment, the water heater 1 corresponds to the "water heater" of the present invention. The combustion device 4 corresponds to the "combustion device" of the present invention. The primary heat exchanger 5 corresponds to the "primary heat exchanger" of the present invention. The peripheral wall 51 corresponds to the "peripheral wall" of the present invention. The opening 515 corresponds to the "opening" of the present invention. The first extension portion 55 corresponds to the "first extension portion" of the present invention. The secondary heat exchanger 6 corresponds to the "secondary heat exchanger" of the present invention. The housing 61 corresponds to the "housing" of the present invention. The inlets 617, 618 correspond to the "inlet" of the present invention. The exhaust hood 10 corresponds to the "exhaust hood" of the present invention. The first hood 110 corresponds to the "first hood" of the present invention. The first main body portion 111 corresponds to the "first main body portion" of the present invention. The second extension portion 112 corresponds to the "second extension portion" of the present invention. The first crimping piece portion 115 corresponds to the "first crimping piece" of the present invention. The abutment portion 116 corresponds to the "abutment portion" of the present invention. The outlet 114 corresponds to the "outlet" of the present invention. The second hood 120 corresponds to the "second hood" of the present invention. The second main body portion 121 corresponds to the "second main body portion" of the present invention. The third extension portion 122 corresponds to the "third extension portion" of the present invention. The fourth extension portion 123 corresponds to the "fourth extension portion" of the present invention. The second crimping piece portion 126 corresponds to the "second crimping piece" of the present invention. The process shown in FIG. 7 (3) corresponds to the "first process" of the present invention. The process shown in FIG. 7 (4) corresponds to the "second process" of the present invention.

The present invention is not limited to the above embodiment, and various modifications are possible. For example, the water heater 1 is not limited to a gas water heater, but may be an oil water heater, etc. Also, the water heater 1 has both a circuit of water pipes for hot water supply and a circuit of water pipes for the bath, but may have only one of the circuits. The water heater 1 may also have a separate water pipe circuit for heating, etc.

The number of the multiple crimping pieces 113 constituting the first crimping piece portion 115 and the number of the multiple crimping pieces 125 constituting the second crimping piece portion 126 may be changed arbitrarily to ensure airtightness between the primary heat exchanger 5 and the exhaust hood 10. The spacing between the multiple crimping pieces 113 constituting the first crimping piece portion 115 may be equal or unequal. The spacing between the multiple crimping pieces 125 constituting the second crimping piece portion 126 may be equal or unequal. In addition, the spacing between the multiple crimping pieces 113 and the spacing between the multiple crimping pieces 125 may be the same or different.

In the molding process of the second hood 120, the upper die 210 and the lower die 220 may be inverted in the vertical relationship. That is, the upper die 210 may be fixed to a bolster of a press machine, the lower die 220 may be fixed to a slide of the press machine, and the lower die 220 may be brought closer to the upper die 210 from above to below, thereby pressing the metal plate 100 to mold the second hood 120. In addition, the direction in which the upper die 210 and the lower die 220 approach each other, i.e., the first direction, is not limited to the vertical direction. Therefore, the first direction may be the left-right direction, and the force F applied to the metal plate 100 and the intermediate product 109 in the molding process of the second hood 120 may be a force along the left-right direction.

REFERENCE SIGNS LIST 1 water heater 4 combustion device 5 primary heat exchanger 6 secondary heat exchanger 10 exhaust hood 51 peripheral wall 55 first extension portion 61 housing 110 first hood 111 first main body portion 112 second extension portion 114 outlet 115 first crimping piece portion 116 abutment portion 120 second hood 121 second main body portion 122 third extension portion 123 fourth extension portion 515 openings 617, 618 inlet

Claims (1)

a primary heat exchanger having a rectangular cylindrical peripheral wall that communicates the combustion exhaust gas generated in the combustion device from below to above;
A secondary heat exchanger having a box-shaped housing and disposed above the primary heat exchanger;
an exhaust hood that communicates the primary heat exchanger and the secondary heat exchanger,
The primary heat exchanger includes a first extension portion extending outward from an opening at an upper end of the peripheral wall,
The secondary heat exchanger includes an inlet for allowing combustion exhaust gas to flow in the rear wall of the housing,
The exhaust hood comprises a first hood and a second hood,
The first hood is
A first main body portion that covers the opening of the primary heat exchanger and bulges upward;
a second extension portion extending outward from a front end and left and right ends of the first main body portion and overlapping a front portion, a left portion, and a right portion of the first extension portion from above;
a first crimping piece portion which is a plurality of crimping pieces provided on an outer edge of the second extending portion in order to crimp the first extending portion;
an abutment portion extending upward, leftward, and rightward from a rear end of the first main body portion to form an outlet through which the combustion exhaust gas that has passed through the peripheral wall flows out, and abutting against the rear wall of the secondary heat exchanger from behind;
The second hood is
A second main body portion that covers the outlet and the inlet, bulges rearward, and has a lower end that is narrowed forward;
a third extension portion extending outward from upper and lower ends and left and right ends of the second main body portion and overlapping the rear wall and the abutment portion of the housing from the rear;
A fourth extension portion that extends rearward from a lower end of the third extension portion and overlaps the entire rear portion of the first extension portion in the left-right direction from above;
A method for manufacturing a water heater comprising: a second crimping piece portion which is a plurality of crimping pieces provided on an outer edge of the fourth extension portion in order to crimp the first extension portion;
In molding the second hood,
When the second hood is attached to the primary heat exchanger and the secondary heat exchanger, a direction corresponding to a front-rear direction is defined as a first direction, and a direction perpendicular to the first direction is defined as a second direction.
a first step of applying a force along the first direction to a metal plate to form the second main body portion and the third extension portion, and providing a portion corresponding to the second crimping piece portion in a manner extending from an end portion on one side in the second direction to one side in the first direction;
a second step of applying a force along the first direction to a portion of the third extension molded in the first step that is continuous with the portion corresponding to the second crimping piece, thereby bending a position of the third extension that is spaced a predetermined length from the portion corresponding to the second crimping piece on the other side of the second direction to the other side of the first direction, to mold the fourth extension and the second crimping piece,
A manufacturing method for a water heater, characterized in that the second crimping piece portion molded at one end of the second hood in the second direction by the first step and the second step extends downward and the second main body portion bulges rearward, the first hood and the second hood are assembled to the primary heat exchanger and the secondary heat exchanger, and the first crimping piece portion and the second crimping piece portion are positioned around the entire circumference of the first extension portion.

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