Hot water storage tank, hot water storage tank unit, method for manufacturing a hot water storage tank, and manufacturing apparatus for a hot water storage tank

Abstract

A hot water tank (30) comprises a hot water tank body (2) that stores hot water thereinside, a thermal insulation structure (20) that covers the hot water tank body (2), and a sheet (40) that is interposed between the hot water tank body (2) and the thermal insulation structure (20) and facilitates separation of the hot water tank body (2) and the thermal insulation structure 20. The thermal insulation structure (20) is integrally shaped to enclose the hot water tank body (2) thereinside and is thereby integrated with the hot water tank body (2).

Description

Hot water storage tank, hot water storage tank unit, and method for manufacturing hot water storage tank

[0001] The present disclosure relates to a hot water storage tank, a hot water storage tank unit, and a method for manufacturing a hot water storage tank.

[0002] In a hot water storage system, the hot water storage tank is surrounded by an insulating material to reduce heat loss from the stored hot water. In recent years, hot water storage tanks using rigid polyurethane foam as an insulating material have become popular. However, because rigid polyurethane foam has strong adhesive properties, it is difficult to separate the rigid polyurethane foam when disposing of the tank.

[0003] Patent Document 1 discloses a technique for disassembling a heat storage tank that uses insulation made of rigid polyurethane foam, in which resin sheets are interposed between the inner tank and the insulation and between the exterior and the insulation. By providing these resin sheets, the rigid polyurethane foam can be easily separated from the inner tank and the exterior of the heat storage tank.

[0004] Japanese Patent Application Publication No. 6-331289

[0005] The sheet described in Patent Document 1 is provided with an injection port for injecting rigid polyurethane foam and air vent holes for venting air. Therefore, if the sheet is not positioned correctly relative to the inner tub and the exterior, problems may arise, such as the rigid polyurethane foam not being able to be injected or the air not being able to be sufficiently vented, resulting in uneven foaming of the polyurethane foam.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a hot water storage tank, a hot water storage tank unit, and a method for manufacturing a hot water storage tank that can easily provide an insulating structure covering the hot water storage tank body and that can easily separate the insulating structure from the hot water storage tank body during decomposition processing.

[0007] The hot water storage tank according to the present disclosure includes a hot water storage tank body that stores hot water therein, a heat insulating structure that covers the hot water storage tank body, and a sheet that is interposed between the hot water storage tank body and the heat insulating structure and that facilitates separation of the hot water storage tank body and the heat insulating structure. The heat insulating structure is integrally formed with the hot water storage tank body by being shaped to encase the hot water storage tank body within.

[0008] According to the present disclosure, the thermal insulation structure is integrally formed in a shape that encases the hot water storage tank body, and because it is integrated with the hot water storage tank body, it can be easily molded using a mold with a molding space. Furthermore, a sheet that facilitates separation of the hot water storage tank body and the thermal insulation structure is interposed between the hot water storage tank body and the thermal insulation structure. This makes it possible to provide a hot water storage tank, a hot water storage tank unit, and a method for manufacturing a hot water storage tank that allows the thermal insulation structure that covers the hot water storage tank body to be easily provided and that allows the thermal insulation structure to be easily separated from the hot water storage tank body during decomposition processing.

[0009] 7 is a perspective view of a hot water storage type water heater including a hot water storage tank unit according to embodiment 1 of the present disclosure; FIG. 8 is a structural diagram of a hot water storage type water heater including a hot water storage tank unit according to embodiment 1 of the present disclosure; FIG. 9 is a perspective view showing the inside of the hot water storage tank unit according to embodiment 1 of the present disclosure; FIG. 10 is a cross-sectional view of the hot water storage tank covered with the heat insulating structure shown in FIG. 3, cut at plane P1 and viewed from the direction of arrow B; FIG. 11 is an enlarged view of part V surrounded by a dashed dotted line of the hot water storage tank covered with the heat insulating structure shown in FIG. 4; 11B, showing the manufacturing method of a hot water storage tank in the order of steps; 12A, showing the manufacturing method of a hot water storage tank in the order of steps; 13A, showing the manufacturing method of a hot water storage tank in the order of steps; 14A, showing the manufacturing method of a hot water storage tank in the order of steps; 15A, showing the manufacturing method of a hot water storage tank in the order of steps; 16A, showing the manufacturing method of a hot water storage tank in the order of steps; 17A, showing the manufacturing method of a hot water storage tank in the order of steps; 18A, showing the manufacturing method of a hot water storage tank in the order of steps; 19A, showing the manufacturing method of a hot water storage tank in the order of steps; 19A, showing the manufacturing method of a hot water storage tank in the order of steps; 20A, showing the manufacturing method of a hot water storage tank in the order of steps; 21A, showing the manufacturing method of a hot water storage tank in the order of steps;

[0010] Hereinafter, a hot water storage tank, a hot water storage tank unit, and a method for manufacturing a hot water storage tank according to an embodiment of the present disclosure will be described with reference to the drawings.

[0011] (Embodiment 1) The overall configuration of a hot water storage type water heater equipped with a hot water storage tank unit of embodiment 1 will be described with reference to Figures 1 and 2. As shown in Figure 1, the front-to-rear direction, the up-down direction, and the left-to-right direction when viewing the hot water storage tank unit 10 from the front are defined, and these directions will be used as appropriate in the following description. The rear of the hot water storage tank unit 10 generally refers to the direction facing the wall.

[0012] 1 and 2, the hot water storage type water heater 1 includes a heat pump unit 8 as a heating means for heating water, and a hot water storage tank unit 10 for storing and supplying water heated by the heat pump unit 8. The heat pump unit 8 and the hot water storage tank unit 10 are connected by a heat pump supply pipe 204, a heat pump return pipe 205, and electrical wiring (not shown).

[0013] 2, the hot water storage tank unit 10 includes a hot water storage tank main body 2 for storing hot water. The hot water storage tank unit 10 also includes a pressure reducing valve 101, a mixing valve 102, a switching valve 103, and a check valve 104 as functional valves for performing the functions of heating, hot water supply, filling, etc., performed by the hot water storage type water heater 1. A cooling pipe (not shown) is connected to the bottom of the hot water storage tank main body 2, and water is supplied from the city water supply.

[0014] The water stored in the lower part of the hot water storage tank body 2 is sent by the heat source pump 105 to the heat pump unit 8 via the heat pump supply pipe 204. The water is then heated to a high temperature by the heat pump unit 8 using heat from the atmosphere, and is returned to the upper part of the hot water storage tank body 2 through the heat pump return pipe 205 and stored there.

[0015] Water with low, medium, and high temperature distributions is stored in layers from bottom to top inside the hot water storage tank body 2. A plurality of temperature sensors 106 are provided vertically on the outer surface of the hot water storage tank body 2 to measure the temperature of the water inside the hot water storage tank body 2. The temperature sensors 106 may be, for example, thermistors.

[0016] The heat pump unit 8 is a heating means for heating the low-temperature water sent from the hot water storage tank body 2. The heat pump unit 8 includes a compressor that compresses a refrigerant, such as carbon dioxide, to a high temperature and high pressure, a condenser that condenses the refrigerant discharged from the compressor and exchanges heat with the low-temperature water sent from the hot water storage tank body 2, a pressure reducing valve that reduces the pressure of the refrigerant from the condenser, and an evaporator that absorbs heat from the atmosphere and evaporates the reduced-pressure refrigerant. The internal configuration of the heat pump unit 8 is not shown in the drawings.

[0017] Next, the structure of the hot water storage tank unit 10 will be described. As shown in FIG. 3 , the hot water storage tank unit 10 includes a hot water storage tank 30, a hot water outlet pipe 11 and a hot water supply pipe 12 (shown in FIG. 4 ) connected to the hot water storage tank main body 2, and an exterior case 80 that houses these components of the hot water storage tank unit 10. The hot water storage tank 30 also includes a hot water storage tank main body 2 that stores hot water therein, an insulating structure 20 that surrounds the hot water storage tank main body 2 to suppress heat dissipation from the stored hot water, and a sheet 40 (shown in FIG. 4 ) serving as a first sheet that is formed on the outer surface of the hot water storage tank main body 2 and interposed between the hot water storage tank main body 2 and the insulating structure 20. Note that FIG. 3 omits the illustration of a portion of the exterior case 80 in order to illustrate the internal structure of the hot water storage tank unit 10. A plane P1 shown in FIG. 3 includes an axis A extending vertically of the hot water storage tank main body 2 and is parallel to the front-to-rear direction of the hot water storage tank unit 10.

[0018] As shown in FIG. 4 , the hot water storage tank body 2 has a cylindrical body 2a and a first end 2b and a second end 2c, each of which is a bowl-shaped end connected to the open end of the body 2a. The first end 2b and the second end 2c form so-called end plates and are welded to the ends of the body 2a. Note that the axis A of the hot water storage tank body 2 passes through the center of the body 2a in a horizontal cross-section of the body 2a. The hot water storage tank body 2 is used with the first end 2b facing upward and the second end 2c facing downward. As shown in FIG. 5 , the first end 2b is provided with a fitting 6a that leads to the interior of the hot water storage tank body 2 and a piping component 7a connected to the fitting 6a. The fitting 6a is attached, for example, at a position where the axis A of the first end 2b passes through. The piping component 7a is made of synthetic resin and is connected to a hot water outlet pipe 11. 4, the second end 2c is provided with a joint 6b that leads to the inside of the hot water storage tank body 2, and a piping component 7b connected to the joint 6b, similar to the first end 2b. The joint 6b is attached perpendicular to the surface of the second end 2c, for example, at a position shifted rearward from the intersection of the second end 2c with the axis A. The piping component 7b is made of synthetic resin and is connected to the hot water supply piping 12.

[0019] The sheet 40 is a shrink film with a thickness of 50 μm to 100 μm that covers the outer surface of the hot water storage tank body 2. The sheet 40 prevents the thermal insulation structure 20 from adhering to the hot water storage tank body 2. Shrink film is used for the sheet 40 because it can easily cover the hot water storage tank body 2. Furthermore, shrink film is very thin, allowing for a thicker thermal insulation structure 20 covering the hot water storage tank body 2. The sheet 40 is preferably made of a material other than rigid polyurethane foam, such as polyethylene, to which rigid polyurethane foam has difficulty adhering. Because the thickness of the sheet 40 is significantly thinner than the thickness of the other components, the sheet 40 is illustrated thicker in each figure than it actually is. As shown in FIG. 5 , the sheet 40 covers the outer surface of the hot water storage tank body 2 up to the outer edge of the insertion hole 2e through which the fitting 6a is inserted. Similarly, as shown in Fig. 4, the sheet 40 covers the outer surface of the hot water storage tank body 2 up to the outer edge of the insertion hole 2f into which the joint 6b is inserted. In this way, the sheet 40 covers the outer surface of the hot water storage tank body 2 without any gaps.

[0020] The thermal insulation structure 20 covers the hot water storage tank body 2 covered by the sheet 40, and also covers the fitting 6a and a portion of the piping component 7a protruding from the hot water storage tank body 2, as shown in FIG. 5. In this way, the tip of the piping component 7a protrudes from the thermal insulation structure 20, while the rest of the piping component 7a is covered by the thermal insulation structure 20. Similarly, as shown in FIG. 4, the tip of the piping component 7b protrudes from the thermal insulation structure 20, while the rest of the piping component 7b is covered by the thermal insulation structure 20. In this way, the thermal insulation structure 20 encases the hot water storage tank body 2 inside, thereby integrating it with the hot water storage tank body 2. The thermal insulation structure 20 has the same shape as the hot water storage tank body 2, and its thickness is uniform throughout. The thermal insulation structure 20 is formed, for example, by foaming and curing rigid polyurethane foam.

[0021] Rigid polyurethane foam is produced by a chemical reaction between a polyol component and an isocyanate component, resulting in high viscosity and strong adhesive strength. Thermal conductivity can also be adjusted by the type of blowing agent added to the polyol component in advance. In this embodiment, rigid polyurethane foam is produced by mixing a polyol component with a viscosity of 100-10,000 mPa·s and an isocyanate component with a viscosity of 50-5,000 mPa·s. Examples of blowing agents that can be used include water, carbon dioxide, cyclopentane, and fluorine-based blowing agents (HFO, HCFO, etc.).

[0022] Next, a manufacturing method of the hot water storage tank 30 will be described. First, a mold 100 for molding the thermal insulation structure 20 will be described. As shown in FIG. 6 , the mold 100 has a first mold 110 and a second mold 120 divided by dividing surfaces 111, 121 that include the vertical direction within the mold. The first mold 110 and the second mold 120 are combined into a rectangular parallelepiped shape by abutting the dividing surfaces 111, 121. As a result, an internal space 130 is formed inside the mold 100, as shown in FIG. 7 , which accommodates the hot water storage tank body 2 and forms a uniform gap between the hot water storage tank body 2 and the internal space 130. This uniform gap is a molding space 135 for molding the thermal insulation structure 20. When the mold 100 accommodates the hot water storage tank body 2 in the internal space 130, the mold 100 accommodates the hot water storage tank body 2 in the internal space 130 in an orientation that is upside down from the orientation used in the hot water storage tank unit 10 shown in Figure 3, i.e., in an orientation where the first end 2b is on the bottom and the second end 2c is on the top.

[0023] The first mold 110 has a rectangular parallelepiped shape as shown in Fig. 7. A parting surface 111 of the first mold 110 has a recess 112 formed by hollowing out the shape of one of the two halves obtained by cutting the hot water storage tank 30 vertically. The second mold 120 also has a rectangular parallelepiped shape, and a parting surface 121 of the second mold 120 has a recess 122 formed by hollowing out the shape of the other of the two halves obtained by dividing the hot water storage tank 30 horizontally. When the first mold 110 and the second mold 120 are combined with their parting surfaces 111 and 121 abutting against each other, the recess 112 and the recess 122 define an internal space 130.

[0024] The mold 100 is formed with accommodating recesses 131 and 132 for accommodating the piping components 7a and 7b connected to the hot water storage tank body 2. As shown in Fig. 8 , the accommodating recess 132 is formed at the position of the axis A on the inside lower part of the mold 100, and the piping component 7a connected to the upper side of the hot water storage tank body 2 is inserted into the accommodating recess 132. As shown in Fig. 11B , the accommodating recess 132 has a recess 132a formed in the first mold 110 and contacting the left half of the piping component 7a, and a recess 132b formed in the second mold 120 and contacting the right half of the piping component 7a. The recesses 132a and 132b clamp the piping component 7a when the mold 100 is closed.

[0025] As shown in Figure 8, the installation recess 131 is formed at a position shifted rearward from the axis A on the upper inside surface of the mold 100, and receives the piping component 7b connected to the underside of the hot water storage tank body 2 during use. The installation recess 131 has a similar configuration to the installation recess 132, and holds the piping component 7b when the mold 100 is closed. The mold 100 also has a urethane injection hole 113 that penetrates downward from the top surface toward the internal space 130. The urethane injection hole 113 is formed forward of the axis A and is formed by combining a recess formed in the parting surface 111 of the first mold 110 with a recess formed in the parting surface 121 of the second mold 120.

[0026] As shown in Fig. 8, the parting surface 121 of the second mold 120 is formed with a plurality of gas vents 133 that communicate the internal space 130 with the external space. The gas vents 133 are ventilation holes for releasing gas generated from the rigid polyurethane foam injected into the mold 100 to the outside. A plurality of horizontally extending gas vents 133 are arranged in the height direction, and a plurality of vertically extending gas vents 133 are arranged in the horizontal direction. The gas vents 133 are formed between the parting surface 121 of the second mold 120 and the parting surface 111 of the first mold 110 by recesses formed in the parting surface 121. When the mold 100 is viewed from the outside, as shown in Fig. 9, the gas vents 133 are slit-shaped openings whose length L along the parting line 107 is greater than their width W. The width W is, for example, 1 mm.

[0027] 8, the gas vent 133 is not located within a height H from the bottom end of the internal space 130. This height H is set to prevent the rigid polyurethane foam injected through the urethane injection hole 113 from entering the gas vent 133 before it becomes viscous. The height H cannot be set uniformly because it depends on various conditions, such as the characteristics and injection amount of the rigid polyurethane foam injected into the mold 100 and the size of the hot water storage tank 30 to be manufactured. However, as an example, the height H is set to one-third of the height of the internal space 130.

[0028] Additionally, a sheet 140 serving as a second sheet is formed in the first mold 110 and the second mold 120. The sheet 140 is vacuum-formed from a non-polar film to which rigid polyurethane foam does not easily adhere, and is made, for example, of a linear low density polyethylene (LLDPE) film with a thickness of 50 μm to 100 μm. The sheet 140 covers the surfaces of the recesses 112 and 122, the parting surfaces 111 and 121, the surfaces of the accommodation recesses 131 and 132, the inner circumferential surface of the urethane injection hole 113, and the gas vent 133.

[0029] Next, a manufacturing method of the hot water storage tank 30 will be described in order of steps. First, as shown in Fig. 10, the hot water storage tank body 2 is prepared (step S11). The joints 6a and 6b shown in Fig. 4 are attached to the hot water storage tank body 2 in advance.

[0030] Next, as shown in Fig. 10, the surface of the hot water storage tank body 2 is covered with a sheet 40 (step S12). Heat is applied to the sheet 40, which is a shrink film, so that the entire outer surface of the hot water storage tank body 2 is completely covered with the sheet 40, as shown in Fig. 11A.

[0031] Next, as shown in Fig. 10, piping components 7a and 7b are attached to the hot water storage tank body 2 (step S13). As shown in Fig. 11A, the piping component 7a is attached to the joint 6a of the hot water storage tank body 2, and the piping component 7b is similarly attached to the other joint 6b shown in Fig. 4.

[0032] 10, the mold 100 is prepared (step S14). That is, the first mold 110 and the second mold 120 described with reference to FIGS. 6 to 9 are prepared.

[0033] Next, mold 100 is covered with sheet 140 (step S15). By vacuum-forming sheet 140 onto mold 100, as shown in Fig. 11B, parting surfaces 111 and 121 of first mold 110 and second mold 120, recesses 112 and 122, cavities 131a and 131b, the inner circumferential surface of urethane injection hole 113 shown in Fig. 8, and the surface of gas vent 133 are covered with sheet 140. By vacuum-forming sheet 140, sheet 140 can also penetrate into processed portions such as cavities 131a and 131b of mold 100, the inner circumferential surface of urethane injection hole 113, and the surface of gas vent 133, thereby covering the surfaces.

[0034] Next, as shown in FIG. 10 , the hot water storage tank body 2 is placed and fixed inside the mold 100 (step S16). At this time, the hot water storage tank body 2 is placed inside the mold 100 in an orientation upside down from the orientation used in the hot water storage tank unit 10 shown in FIG. 3 . Then, as shown in FIG. 11B , the first mold 110 and the second mold 120 are combined, and the piping component 7a is sandwiched between the recessed portion 132a of the first mold 110 and the recessed portion 132b of the second mold 120. Similarly, the other piping component 7b is sandwiched in the installation recess 131. As a result, as shown in FIG. 12A , the hot water storage tank body 2 can be held in a state in which a uniform molding space 135 is formed between the recessed portions 112 and 122 of the mold 100.

[0035] Next, as shown in Fig. 10, rigid polyurethane foam is injected into the interior of the mold 100 (step S17). The rigid polyurethane foam is injected through a nozzle (not shown) inserted into the urethane injection hole 113 shown in Fig. 8. This nozzle is connected to a mixing head (not shown) that mixes the materials for the rigid polyurethane foam.

[0036] The rigid polyurethane foam injected from the nozzle fills the molding space 135 between the mold 100 and the hot water storage tank body 2 from below in a liquid state, and eventually expands while becoming viscous. During this process, the air inside the mold 100 escapes to the outside through the gas vent 133 shown in Figure 8. Eventually, the rigid polyurethane foam fills the molding space 135 and hardens. The hardened rigid polyurethane foam forms the insulating structure 20 that covers the hot water storage tank body 2.

[0037] 12B, the first mold 110 and the second mold 120 are separated in the left-right direction perpendicular to the axis A and demolded (step S18). This allows the hot water storage tank 30 to be manufactured, in which the surface of the hot water storage tank body 2 is tightly and tightly covered by the thermal insulation structure 20, and the thermal insulation structure 20 and the hot water storage tank body 2 are integrated together. The thermal insulation structure 20 is integrally formed in a shape that encases the oil storage tank body 2. This allows the thermal insulation structure 20 to be held by the oil storage tank body 2 and will not fall off from the oil storage tank body 2.

[0038] As described above, according to the first embodiment, the thermal insulation structure 20 is integrated with the hot water storage tank body 2 by enclosing the hot water storage tank body 2 therein. Therefore, the thermal insulation structure 20 that covers the hot water storage tank body 2 can be easily molded using a mold provided with the molding space 135 for the thermal insulation structure 20.

[0039] Furthermore, a sheet 40 to which rigid polyurethane foam does not easily adhere is interposed between the hot water storage tank body 2 and the insulating structure 20 that covers the hot water storage tank body 2. When disposing of the product, the insulating structure 20 can be easily separated from the hot water storage tank body 2 by breaking the shape of the insulating structure 20, which is integrally formed from rigid polyurethane foam and envelops the hot water storage tank body 2. This shortens the processing time for the hot water storage tank 30 and allows the separated components to be reused as resources.

[0040] Furthermore, a sheet 140 to which rigid polyurethane foam does not easily adhere is placed in the recesses 112, 122 of the mold 100 used to mold the thermal insulation structure 20. This allows the mold 100 to be easily separated from the thermal insulation structure 20 when demolding, making it easy to mold the thermal insulation structure 20.

[0041] Furthermore, a non-polar film is used for the sheet 140 that covers the mold 100. This allows the sheet 140 to be used repeatedly.

[0042] Furthermore, recesses formed in the parting surface 121 of the second mold 120 form a plurality of gas vents 133 that communicate the internal space 130 with the external space. This allows the sheet 140 to fit into and cover the gas vents 133 formed in the second mold 120 when vacuum-forming the sheet 140. This prevents problems such as air being unable to escape from the mold 100 due to the sheet 140 being covered, allowing the thermal insulation structure 20 to be smoothly molded. Furthermore, since the urethane injection hole 113 is formed in the parting surface between the first mold 110 and the second mold 120, the sheet 140 can fit into and cover the inner periphery of the urethane injection hole 113 when vacuum-forming the sheet 140. This allows the thermal insulation structure 20 to be smoothly molded without preventing problems such as an inability to inject rigid polyurethane foam.

[0043] Furthermore, since the gap between the mold 100 and the hot water storage tank body 2 is used as a space for molding the thermal insulation structure 20, the thermal insulation structure 20 can be formed into any shape by changing the shape of the mold 100. Therefore, as in this embodiment, it is possible to make the thickness of the thermal insulation structure 20 uniform throughout. Furthermore, since the thermal insulation structure 20 can be molded seamlessly, it is possible to mold a thermal insulation structure 20 with higher thermal insulation performance.

[0044] Furthermore, the gas vent 133 is located at a height that prevents the rigid polyurethane foam from entering before it becomes viscous, and is not provided within a height H from the lower end of the internal space 130. This prevents the rigid polyurethane foam from leaking out of the gas vent 133 and also prevents burrs from forming on the heat insulating structure 20 after molding.

[0045] Furthermore, when molding the thermal insulation structure 20, the piping components 7a, 7b of the hot water storage tank 30 are sandwiched between the mold 100, thereby fixing the hot water storage tank body 2 inside the mold 100. This eliminates the need to prepare additional members for fixing the hot water storage tank body 2, simplifying the manufacturing process for the thermal insulation structure 20. Furthermore, since the rigid polyurethane foam can be molded around the piping components 7a, 7b, heat radiation from the hot water storage tank 30 can be suppressed, improving the thermal insulation performance.

[0046] Furthermore, the hot water storage tank body 2 is inverted upside down when it is placed in the mold 100 to mold the insulation structure 20 and when it is installed in the hot water storage tank unit 10 as a finished product. When molding the insulation structure 20, the rigid polyurethane foam injected from above accumulates at the bottom of the molding space 135 and then gradually expands to fill the upper portion. As a result, a portion with high insulation performance is formed on the lower side of the insulation structure 20 and a portion with low insulation performance is formed on the upper side. On the other hand, when the hot water storage tank unit 10 is in use, the hot water storage tank body 2 stores high-temperature water in the upper portion and low-temperature water in the lower portion. Therefore, by inverting the hot water storage tank 30 upside down during use and during manufacture, the upper side of the hot water storage tank body 2, where high-temperature water is stored, can be covered with a portion with high insulation performance.

[0047] (Embodiment 2) Next, embodiment 2 will be described. In embodiment 1, when the hot water storage tank body 2 is fixed to the mold 100, the piping components 7a and 7b connected to the hot water storage tank body 2 are clamped by the mold 100. However, in this embodiment, the hot water storage tank body 2 is fixed to the mold 200 using a jig 150 as shown in Fig. 13A. In the following description, the configurations different from embodiment 1 will be mainly described, and similar configurations will be assigned the same reference numerals and detailed description will be omitted.

[0048] As shown in Fig. 13A, the mold 200 has a first mold 210 and a second mold 220. The first mold 210 and the second mold 220 are formed with an accommodating recess 230 for accommodating a protrusion 154 of a jig 150, which will be described later. Although Fig. 13A shows only the lower part of the mold 200, the accommodating recess 230 is also similarly formed on the upper part of the mold 200 at a position corresponding to the joint 6b.

[0049] The jig 150 is made of a material to which rigid polyurethane foam does not easily adhere, such as polypropylene. The jig 150 has a base portion 151 that contacts the inner surface of the mold 200, a protruding portion 152 that protrudes from the base portion 151, a surrounding portion 153 that surrounds the protruding portion 152 and contacts the hot water storage tank main body 2 at its tip, and a protruding portion 154 that protrudes from the base portion 151.

[0050] The base portion 151 is cylindrical, and the surface that contacts the mold 200 is formed in a shape that matches the inner surface of the mold 200. The protruding portion 152 is a cylindrical portion having an outer diameter equal to the inner diameter of the fitting 6a and protruding from the center of the base portion 151. The protruding portion 152 is inserted into the hot water storage tank body 2 from the fitting 6a of the hot water storage tank body 2 housed in the mold 200. The surrounding portion 153 contacts the hot water storage tank body 2 at its tip, forming a molding space 235 for molding the thermal insulation structure 240 between the mold 200 and the hot water storage tank body 2. The protruding portion 154 protrudes from the base portion 151 in the direction opposite to the protruding portion 152. The protruding portion 154 serves as an engaging portion and engages with an accommodation recess 230 formed in the mold 200. This limits horizontal movement of the jig 150 housed in the mold 200.

[0051] To mold the thermal insulation structure 240, first, as shown in Figure 13A, the protrusion 152 is inserted into the joint 6a and the jig 150 is installed on the hot water storage tank body 2. The jig 150 is also installed on the upper joint 6b of the hot water storage tank body 2 in a similar manner. The protrusion 154 is then installed in the installation recess 230 to fix the hot water storage tank body 2 inside the mold 200. Next, rigid polyurethane foam is injected through the urethane injection hole 113 to mold the thermal insulation structure 240 shown in Figure 13B. After the mold 200 is demolded, the jig 150 is removed, and the hot water storage tank 260 can be manufactured.

[0052] The heat insulating structure 240 thus formed has openings 220a around the joints 6a and 6b where no heat insulating material is formed. The joints 6a and 6b can be connected to the piping components 7a and 7b through the openings 220a.

[0053] According to the second embodiment, the jig 150 is formed with protrusions 152 to be inserted into the joints 6a, 6b, and a protrusion 154 to be accommodated in the accommodation recess 230. This allows the hot water storage tank body 2 to be held in the mold 200 while ensuring a molding space 235 for the heat insulating structure 240, and the heat insulating structure 240 can be easily molded around the hot water storage tank body 2.

[0054] (Embodiment 3) Next, a description will be given of embodiment 3. In this embodiment, as shown in Fig. 14A, the hot water storage tank body 2 is fixed in the mold 300 by attaching a heat insulating cover 250 to the hot water storage tank body 2.

[0055] The mold 300 has a first mold 310 and a second mold 320. The first mold 310 has a urethane injection hole (not shown) that extends horizontally from the side surface to the recess 312.

[0056] The insulating cover 250 is used to secure the hot water storage tank body 2 inside the mold 300. The insulating cover 250 is formed from EPS (Expanded Polystyrene) insulating material, which is a type of foam plastic insulating material. The insulating cover 250 covers the first end 2b and the second end 2c (FIG. 3) of the hot water storage tank body 2, which are cup-shaped, and is interposed between the hot water storage tank body 2 and the mold 300 to ensure a molding space 335. Note that the insulating cover 250 is cup-shaped and covers the first end 2b and the second end 2c (FIG. 3), sandwiching the hot water storage tank body 2 from above and below, thereby stabilizing the position of the hot water storage tank body 2 within the mold 300. An opening 251 is formed at the top of the insulating cover 250, which is located on the lower side, to expose the joint 6a. Similarly, an opening for exposing the other joint 6b is formed in the heat insulating cover 250 arranged on the upper side at a position offset from the top.

[0057] In this way, the hot water storage tank body 2 with the insulating covers 250 attached to the top and bottom is placed in the mold 300, and hard polyurethane resin is injected through a urethane injection hole (not shown) formed in a position outside the area covered by the insulating cover 250. This forms the urethane insulation member 340 shown in Figure 14B. The hot water storage tank 360 can then be manufactured by demolding the mold 300.

[0058] In the hot water storage tank 360 manufactured in this manner, the cylindrical body 2a is covered with a urethane insulation member 340, and the upper and lower bowl-shaped first and second ends 2b and 2c are covered with an insulation cover 250. The urethane insulation member 340 is bonded to the insulation cover 250 to form an insulation structure 350 together with the insulation cover 250, which encases the hot water storage tank body 2. The insulation cover 250 is used as is as part of the insulation material of the hot water storage tank 360. Note that openings 251 formed in the insulation cover 250 provide space around the fittings 6a and 6b for connecting piping components 7a and 7b.

[0059] According to the third embodiment, the hot water storage tank body 2 is sandwiched from above and below by the insulating cover 250, so that the hot water storage tank body 2 can be fixed to the mold 300 while ensuring a molding space 335 for the urethane insulating member 340. This makes it possible to easily mold the insulating structure 350 around the hot water storage tank body 2.

[0060] This disclosure is not limited to the above embodiment, and various modifications and applications are possible. In the above embodiment, the piping components 7a, 7b connected to the fittings 6a, 6b are clamped by the mold 100 to fix the hot water storage tank body 2 within the mold 100. However, the components clamped by the mold are not limited to the piping components 7a, 7b. For example, any connecting component connected to the hot water storage tank body 2 that can be clamped by the mold may be used, and for example, the fittings 6a, 6b of the hot water storage tank body 2 may be clamped.

[0061] Furthermore, although three methods for fixing the hot water storage tank body 2 to the mold have been described, namely, clamping the piping components 7a and 7b with the mold, installing the jig 150, and installing the insulating cover 250, different methods may be combined as appropriate for the top and bottom of the hot water storage tank body 2. Furthermore, fixing methods other than the above three methods may be used as long as they can fix the hot water storage tank body 2 while maintaining the molding space within the mold. For example, one of the above three methods may be used only on the bottom side to fix the height position of the hot water storage tank body 2, and additional supports may be provided to support the sides of the hot water storage tank body 2 to stabilize its posture.

[0062] Although the shrink film covering the hot water storage tank body 2 is described as being made of polyethylene, any material can be selected as long as it is a material to which rigid polyurethane foam does not easily adhere. For example, it can be made of polypropylene or polyolefin.

[0063] Furthermore, the material of the sheet 140 covering the mold is not particularly limited as long as it is difficult for the rigid polyurethane foam to adhere to it and can be vacuum formed. For example, high-density polyethylene (HDPE), low-density polyethylene (LDPE), polypropylene (PP), etc. can be used for the sheet 140.

[0064] Furthermore, as engaging portions provided on the jig 150 and the mold 200, a protrusion 154 is provided on the jig 150, and an accommodating recess 230 that accommodates the protrusion 154 is provided on the mold 200, thereby restricting the movement of the jig 150. However, the relationship between these protrusions and recesses may be reversed, and a recess may be formed on the jig 150 and a protrusion on the mold 200.

[0065] Furthermore, the rigid polyurethane material to be injected may be changed to one with different performance during the molding process of the thermal insulation structure. For example, a rigid polyurethane foam with high thermal insulation performance may be first injected and foamed, and then a rigid polyurethane foam with low thermal insulation performance may be injected and foamed. This allows the appropriate material to be used depending on the required thermal insulation performance, enabling optimal thermal insulation design and reducing manufacturing costs.

[0066] It has also been explained that when molding the thermal insulation structure, the hot water tank body 2 is oriented with the axis A facing up and down, and the mold that houses the hot water tank body 2 is divided by a dividing line 107 that extends up and down parallel to the axis A. However, the orientation of the hot water tank body 2 and the direction in which the mold is divided can be changed as appropriate.

[0067] For example, as shown in Fig. 15A, when molding the thermal insulation structure, the hot water storage tank body 2 may be oriented with axis A facing up and down, and a mold 400 that houses the hot water storage tank body 2 may be divided into a first mold 410 and a second mold 420 by a parting line 401 perpendicular to axis A. The hot water storage tank body 2 may be fixed inside the mold 400 using a jig 150 shown in Fig. 13A, an insulating cover 250 shown in Fig. 14A, or other fixing methods. The rigid polyurethane foam may be injected through a urethane injection hole 413 drilled downward from the top surface of the first mold 410, thereby molding the thermal insulation structure that covers the hot water storage tank body 2.

[0068] 15B , when molding the thermal insulation structure, the hot water storage tank body 2 may be oriented with axis A facing left-right, and a mold 500 that houses the hot water storage tank body 2 may be divided into a first mold 510 and a second mold 520 by a parting line 501 perpendicular to axis A. The hot water storage tank body 2 may be fixed inside the mold 500 using a jig 150 shown in FIG. 13A , an insulating cover 250 shown in FIG. 14A , or other fixing methods. The rigid polyurethane foam may be injected through a urethane injection hole 513 drilled downward from the top surface of the first mold 510, thereby molding the thermal insulation structure that covers the hot water storage tank body 2.

[0069] 15C , when molding the thermal insulation structure, the hot water storage tank body 2 may be oriented with its axis A facing left-right, and a mold 600 containing the hot water storage tank body 2 may be divided into a first mold 610 and a second mold 620 by a parting line 601 parallel to the axis A. The hot water storage tank body 2 can be fixed inside the mold 600 by clamping the piping components 7a and 7b shown in FIG. 12A with the mold, installing a jig 150 shown in FIG. 13A , installing an insulating cover 250 shown in FIG. 14A , or by other fixing methods. The rigid polyurethane foam can be injected through a urethane injection hole 613 drilled downward from the top surface of the first mold 610 to mold the thermal insulation structure covering the hot water storage tank body 2.

[0070] 15B and 15C, when molding the thermal insulation structure, the hot water tank body 2 is placed on its side, thereby lowering the vertical height of the molding space into which the rigid polyurethane foam is injected. This reduces the difference in thermal insulation performance between the lower and upper parts of the thermal insulation structure, making it possible to mold a thermal insulation structure with uniform thermal insulation performance throughout.

[0071] The present disclosure allows various embodiments and modifications without departing from the broad spirit and scope of the present disclosure. Furthermore, the above-described embodiments are intended to explain the present disclosure and do not limit the scope of the present disclosure. That is, the scope of the present disclosure is defined by the claims, not the embodiments. Various modifications made within the scope of the claims and the meaning of equivalent disclosures are considered to be within the scope of the present disclosure.

[0072] Various aspects of the present disclosure are summarized below as appendices.

[0073] (Supplementary Note 1) A hot water storage tank comprising: a hot water storage tank body that stores hot water therein; a heat insulating structure that covers the hot water storage tank body; and a sheet that is interposed between the hot water storage tank body and the heat insulating structure and that facilitates separation of the hot water storage tank body and the heat insulating structure, wherein the heat insulating structure is integrally formed with the hot water storage tank body by being shaped to encase the hot water storage tank body within. (Supplementary Note 2) The hot water storage tank according to Supplementary Note 1, wherein a portion of a piping component connected to the hot water storage tank body protrudes from the heat insulating structure. (Supplementary Note 3) The hot water storage tank according to Supplementary Note 1, wherein the heat insulating structure is formed with an opening for exposing a joint of the hot water storage tank body to which the piping component is connected. (Supplementary Note 4) The hot water storage tank according to any one of Supplements 1 to 3, wherein the heat insulating structure is formed from rigid polyurethane foam. (Appendix 5) The hot water storage tank according to any one of Appendices 1 to 3, wherein the thermal insulation structure includes: an insulating member formed from a rigid polyurethane foam covering a barrel portion of the hot water storage tank body; and an insulating member formed from foamed plastic covering an end portion of the hot water storage tank body, the insulating member being integrated with the insulating member by the adhesive strength of the rigid polyurethane foam. (Appendix 6) The hot water storage tank according to Appendices 4 or 5, wherein the sheet covers the outer surface of the hot water storage tank body and is formed from a material to which the rigid polyurethane foam does not easily adhere. (Appendix 7) A hot water storage tank unit comprising: the hot water storage tank according to any one of Appendices 1 to 6; a hot water supply pipe connected to the hot water storage tank for supplying hot water to the hot water storage tank; a hot water outlet pipe connected to the hot water storage tank for discharging hot water from the hot water storage tank; and an outer case that houses the hot water storage tank, the hot water supply pipe, and the hot water outlet pipe inside.(Appendix 8) A method for manufacturing a hot water storage tank, comprising the steps of: covering an outer peripheral surface of a hot water storage tank body that stores hot water therein with a first sheet; covering a mold for molding an insulating structure that covers the hot water storage tank body with a second sheet that facilitates separation from the insulating structure; accommodating and fixing the hot water storage tank body whose outer peripheral surface is covered with the first sheet inside the mold that is covered with the second sheet; injecting rigid polyurethane foam into the space between the hot water storage tank body and the mold to mold the insulating structure; and demolding the mold to remove the hot water storage tank whose periphery is covered with insulating material. (Appendix 9) A method for manufacturing a hot water storage tank according to Appendix 8, wherein when accommodating and fixing the hot water storage tank body inside the mold, a connecting part connected to the hot water storage tank body is clamped by the mold to fix the hot water storage tank body. (Appendix 10) The method for manufacturing a hot water storage tank according to Appendix 8, wherein, when the hot water storage tank body is accommodated and fixed inside the mold, a jig having a protrusion to be inserted into the hot water storage tank and an engaging portion that engages with the mold is attached by inserting the protrusion into the hot water storage tank body and engaging the engaging portion with the mold, thereby fixing the hot water storage tank body inside the mold. (Appendix 11) The method for manufacturing a hot water storage tank according to Appendix 8, wherein, when the hot water storage tank body is accommodated and fixed inside the mold, an insulating cover made of foamed plastic is attached to an end of the hot water storage tank body, and the insulating cover is interposed between the mold and the hot water storage tank body, thereby fixing the hot water storage tank body inside the mold. (Appendix 12) The method for manufacturing a hot water storage tank according to any one of Appendices 8 to 11, wherein a gas vent is formed on a parting surface of the mold to release air from inside. (Supplementary Note 13) The method for manufacturing a hot water storage tank according to Supplementary Note 12, wherein the gas vent is formed at a height that prevents the injected rigid polyurethane foam from entering in a liquid state.

[0074] This application is based on Japanese Patent Application No. 2023-025635, filed on February 21, 2023. The entire specification, claims, and drawings of Japanese Patent Application No. 2023-025635 are incorporated herein by reference.

[0075] 1 Storage type water heater, 2 Storage tank body, 2a Body, 2b First end, 2c Second end, 2e, 2f Insertion hole, 6a, 6b Joint, 7a, 7b Piping parts, 8 Heat pump unit, 10 Storage tank unit, 11 Hot water outlet pipe, 12 Hot water supply pipe, 20 Heat insulating structure, 30 Storage tank, 40 Sheet, 80 Outer case, 100 Mold, 101 Pressure reducing valve, 102 Mixing valve, 103 Switching valve, 104 Check valve, 105 Heat source pump, 106 Temperature sensor, 107 Parting line, 110 First mold, 111 Parting surface, 112 Recess, 113 Urethane injection hole, 120 Second mold, 121 Parting surface, 122 Recess, 130 Internal space, 131 Accommodating recess, 132 Storage recess, 132a, 132b: hollow portion, 133: gas vent, 135: molding space, 140: sheet, 150: jig, 151: base portion, 152: protrusion, 153: surrounding portion, 154: protrusion, 200: mold, 204, 205: piping, 210: first mold, 220: second mold, 220a: opening, 230: storage recess, 235: molding space, 240: heat insulating structure, 250: heat insulating cover, 251: opening, 260: hot water storage tank, 300: mold, 310: first mold, 312: recess, 320: second mold, 335: molding space, 340: urethane heat insulating member, 350: heat insulating structure, 360: hot water storage tank, 400: mold, 401: parting line, 410: first mold, 413: urethane injection hole, 420 Second mold, 500 mold, 501 parting line, 510 first mold, 513 urethane injection hole, 520 second mold, 600 mold, 601 parting line, 610 first mold, 613 urethane injection hole, 620 second mold, A axis, P1 plane.

Claims

1. A hot water storage tank body that stores hot water inside; A heat insulating structure covering the hot water storage tank body; a sheet interposed between the hot water tank body and the heat insulating structure to facilitate separation of the hot water tank body and the heat insulating structure; The heat insulating structure is integrally formed in a shape that envelops the hot water storage tank body, and is integrated with the hot water storage tank body. Hot water tank.

2. The sheet contacts the hot water storage tank body and the thermal insulation structure. The hot water storage tank according to claim 1.

3. The sheet covers an outer surface of the hot water storage tank body, The heat insulating structure covers the sheet and forms the outermost part of the hot water storage tank. The hot water storage tank according to claim 2.

4. A part of a piping component connected to the hot water storage tank body protrudes from the thermal insulation structure. The hot water storage tank according to claim 1.

5. The heat insulating structure has an opening for exposing a joint of the hot water storage tank body to which the piping part is connected. The hot water storage tank according to claim 1.

6. The heat insulating structure is formed from a rigid polyurethane foam. The hot water storage tank according to claim 1.

7. The thermal insulation structure includes: A heat insulating member made of a rigid polyurethane foam covering a body of the hot water storage tank body; and a heat insulating member that is made of foamed plastic covering the end of the hot water storage tank body and is integrated with the heat insulating member by the adhesive force of a rigid polyurethane foam. The hot water storage tank according to claim 1.

8. The sheet covers the outer surface of the hot water storage tank body and is made of a material to which rigid polyurethane foam is difficult to adhere. The hot water storage tank according to claim 6.

9. A hot water storage tank according to any one of claims 1 to 8; A hot water supply pipe connected to the hot water storage tank for supplying hot water to the hot water storage tank; A hot water outlet pipe connected to the hot water storage tank for outletting hot water from the hot water storage tank; The hot water storage tank, the hot water supply pipe, and the hot water outlet pipe are housed in an exterior case. Hot water tank unit.

10. A step of covering an outer peripheral surface of a hot water storage tank body that stores hot water therein with a first sheet; A step of covering a mold for forming a heat insulating structure covering the hot water storage tank body with a second sheet for facilitating separation from the heat insulating structure; A process of placing and fixing the hot water storage tank body, the outer peripheral surface of which is covered with the first sheet, inside the mold, the mold being covered with the second sheet; A step of injecting a rigid polyurethane foam into a space between the hot water storage tank body and the mold to mold the thermal insulation structure; and removing the mold from the hot water tank surrounded by a heat insulating material. A method for manufacturing a hot water tank.

11. When the hot water storage tank body is accommodated and fixed inside the mold, a connection part connected to the hot water storage tank body is clamped by the mold to fix the hot water storage tank body. A method for manufacturing the hot water tank according to claim 10.

12. When the hot water tank body is accommodated and fixed inside the mold, a jig having a protrusion that is inserted into the hot water tank body and an engagement portion that engages with the mold is attached to the hot water tank body by inserting the protrusion into the hot water tank body, and the engagement portion is engaged with the mold, thereby fixing the hot water tank body inside the mold. A method for manufacturing the hot water tank according to claim 10.

13. When the hot water tank body is accommodated and fixed inside the mold, an insulating cover made of foamed plastic is attached to an end of the hot water tank body, and the insulating cover is interposed between the mold and the hot water tank body, and the hot water tank body is fixed inside the mold. A method for manufacturing the hot water tank according to claim 10.

14. A gas vent for releasing internal air is formed on the parting surface of the mold. A method for manufacturing the hot water tank according to any one of claims 10 to 13.

15. The gas vent is formed at a height such that the injected rigid polyurethane foam does not penetrate in a liquid state. A method for manufacturing the hot water tank according to claim 14.

16. The hot water tank body is housed and fixed inside the mold in a position that is upside down from the position when in use, The rigid polyurethane foam is injected from above into the space between the hot water tank body and the mold. A method for manufacturing the hot water tank according to claim 10.

17. A mold having a first mold and a second mold that are combined by abutting each other's divided surfaces, a recess for accommodating a hot water tank body for storing hot water therein and forming a molding space for molding a heat insulating structure covering the hot water tank body is provided on a parting surface of the first mold and a parting surface of the second mold, the mold has an injection port for injecting a rigid polyurethane foam into the molding space, and the rigid polyurethane foam injected from the injection port forms the outermost part of the hot water storage tank as the thermal insulation structure; Hot water tank manufacturing equipment.

18. When the first mold and the second mold are combined, the mold clamps a connection part connected to the hot water storage tank body to fix the hot water storage tank body. An apparatus for manufacturing the hot water tank according to claim 17.

19. A jig having a protrusion inserted into the inside of the hot water storage tank body and an engagement portion that engages with the mold, The jig is attached to the hot water tank body by inserting the protrusion into the hot water tank body, and the engagement portion is engaged with the mold, so that the hot water tank body is fixed inside the mold. An apparatus for manufacturing the hot water tank according to claim 17.

20. Further comprising an insulating cover formed from foamed plastic, The heat insulating cover is attached to an end of the hot water storage tank body and is interposed between the mold and the hot water storage tank body to fix the hot water storage tank body inside the mold. An apparatus for manufacturing the hot water tank according to claim 17.

21. A gas vent for venting air from the molding space is formed on the parting surface of the mold. An apparatus for manufacturing the hot water tank according to claim 17.

22. The gas vent is formed at a height not lower than the height at which the rigid polyurethane foam injected from above into the lower part of the molding space penetrates in a liquid state, but is formed at a height higher than that. An apparatus for manufacturing the hot water tank according to claim 21.