WO2021020527A1

WO2021020527A1 - Method for manufacturing heat-generating element, heat-generating element, and heating unit

Info

Publication number: WO2021020527A1
Application number: PCT/JP2020/029315
Authority: WO
Inventors: 幸春宮村
Original assignee: 幸春宮村
Priority date: 2019-07-30
Filing date: 2020-07-30
Publication date: 2021-02-04
Also published as: JPWO2021020527A1; JP7029867B2

Abstract

This method for manufacturing a heat-generating element 1 inductively heated by a coil comprises: a first step for manufacturing a perforated plate 11 by forming a plurality of holes 11A in a plate made of an inductively heatable material; a second step for layering a plurality of the perforated plates 11 so that the respective holes 11A in the perforated plates 11 are in communication; and a third step for joining the plurality of stacked perforated plates 11 by diffusion bonding. This heating unit has a preheating channel for channeling water along the outer periphery of a coil, and is configured so that water fed to the preheating channel passes through the preheating channel and then passes through a passage in a heat-generating element.

Description

Manufacturing method of heating element, heating element and heating unit

The present invention relates to a method for manufacturing a heating element that is induced and heated by a coil, a heating element, and a heating unit.

Conventionally, a heating element that is induced and heated by a coil is known as a heat source for a water heater (see, for example, Japanese Patent Application Laid-Open No. 9-145156). In this technique, the heating element is columnar and has a plurality of passages along the axial direction. The heating element in this technique is configured by drilling a metal rod.

However, in the conventional method of manufacturing a heating element by drilling, for example, when the length of the metal rod is large, it may be difficult to form a passage, so a relatively long heating element is made. There is a problem that it cannot be done.

Therefore, the present invention presents a method for manufacturing a heating element that can satisfactorily manufacture even a relatively long heating element, a heating element suitable for manufacturing by this manufacturing method, and a heating unit including the heating element. The purpose is to provide.

In order to solve the above problems, the method for manufacturing a heating element according to the present invention is a method for manufacturing a heating element that is induced and heated by a coil, and is formed by forming a plurality of holes in a plate made of a material that can be induced and heated. , The first step of manufacturing the perforated plate, the second step of superimposing the plurality of the perforated plates in a state where the holes of the perforated plates communicate with each other, and joining the plurality of the superposed perforated plates by diffusion joining. It includes a third step.

According to this manufacturing method, a heating element having a plurality of passages can be manufactured by superimposing a plurality of perforated plates and joining them by diffusion bonding. Therefore, the length of the heating element is set to an arbitrary size. And even a relatively long heating element can be satisfactorily manufactured. Further, by joining a plurality of perforated plates by diffusion bonding, the materials of the perforated plates are integrated with each other, so that the heat transfer property in the flow path direction of the heating element is not impaired, and heat can be transferred with high efficiency. Further, unlike the case where a plurality of perforated plates are bonded with an adhesive, for example, the adhesive does not protrude into the holes of the perforated plates, so that the flow of water in the flow path can be improved.

Further, in the first step, a plurality of holes may be formed in the plate by etching.

According to this, even a very small hole can be formed well on the plate, so that the outer diameter of the heating element can be reduced. Further, by reducing the outer diameter of the heating element in this way, the action of the magnetic field of the coil can be satisfactorily applied to the portion forming the passage near the center of the heating element, so that the passage near the center of the heating element can be satisfactorily exerted. The water flowing through the water can be heated well.

Further, in the first step, protrusions may be formed on the inner peripheral surface of the hole.

According to this, since a protrusion is provided in the passage of the heating element, it is possible to prevent foreign matter from blocking the passage, and to increase the contact area with water to improve the heat transfer performance. it can.

Further, in the first step, the plurality of holes may be formed in a regular hexagon shape and arranged in a honeycomb shape.

According to this, the rigidity of the heating element can be increased, and the shape of the hole can be kept good.

Further, in the second step, the holes may be arranged in a spiral shape by superimposing the plurality of adjacent perforated plates in a shifted phase.

According to this, since the passage formed in the heating element is formed in a spiral shape, the water passing through the spiral passage can be evenly contacted with the inner wall of the passage. Therefore, the heat from the heating element can be efficiently transferred to the water flowing through the passage. Further, by making the passage spiral, for example, the length of the passage with respect to the length of the heating element can be increased as compared with the case where the passage is formed in a straight line. Heat can be transferred efficiently.

Further, the heating element according to the present invention is a heating element that is induced and heated by a coil, and has a plurality of passages through which water can pass. The heating element has protrusions on the inner peripheral surface of the passage.

According to this, the protrusions in the passage can prevent foreign matter from entering the passage, and the contact area with water can be increased to improve the heat transfer performance.

Further, the protrusion may be provided at least at the entrance of the passage.

According to this, since the protrusion at the entrance of the passage can suppress the entry of foreign matter into the passage, the clogging of the passage due to the foreign matter can be satisfactorily suppressed.

Further, the protrusion may extend in a rib shape from the entrance of the passage toward the exit.

According to this, the contact area with water can be further increased, so that the heat transfer performance can be further improved.

Further, the heating element according to the present invention is a heating element that is induced and heated by a coil, and has a plurality of passages through which water can pass. The plurality of passages have regular hexagonal openings, and the openings are arranged in a honeycomb shape.

Further, the heating element according to the present invention is a heating element that is induced and heated by a coil, and has a plurality of passages through which water can pass. The passage is formed in a spiral shape.

According to this, since the water passing through the spiral passage can be evenly contacted with the inner wall of the passage, the heat from the heating element can be efficiently transferred to the water flowing through the passage. Further, by making the passage spiral, for example, the length of the passage with respect to the length of the heating element can be increased as compared with the case where the passage is formed in a straight line. Heat can be transferred efficiently.

Further, the heating unit according to the present invention is a heating unit including the heating element, and preheats to form a coil for inducing heating the heating element and a preheating flow path for flowing water along the outer circumference of the coil. It includes a flow path forming member.
The preheating channel is connected to the passage of the heating element, and the water supplied to the preheating channel is configured to pass through the passage of the heating element after passing through the preheating channel. There is.

According to this, since the coil can be cooled by the water passing through the preheating flow path, the coil can be cooled more efficiently than, for example, air cooling. Further, since the water passing through the preheating flow path is heated in the passage of the heating element after removing the heat of the coil, the water can be efficiently heated.

Further, the preheating flow path forming member is a first housing having a cylindrical first outer peripheral wall centered on the heating element, and a second outer peripheral wall having a diameter larger than that of the first outer peripheral wall. A second housing having a second outer peripheral wall that forms the preheating flow path with the first outer peripheral wall by being arranged at a distance from the first outer peripheral wall may be provided.

According to this, since the preheating flow path can be formed over the entire circumference of the first outer peripheral wall of the first housing, the heat of the coil can be efficiently absorbed by the water passing through the preheating flow path.

Further, the preheating flow path may be formed spirally with respect to the first outer peripheral wall.

According to this, since the length of the preheating flow path can be increased, the heat of the coil can be absorbed more efficiently by the water passing through the preheating flow path.

Further, the second housing may have ribs protruding from the inner peripheral surface of the second outer peripheral wall, and the ribs may be formed in a spiral shape.

It is sectional drawing which shows the hot water supply equipment provided with the heating element which concerns on this embodiment. It is a perspective view (a) which shows a heating element, and the figure (b) which shows the relationship between a hole and a section part. It is a figure which shows the 1st process which manufactures a perforated plate. It is a figure (a), (b) which shows the 2nd process of laminating the perforated plate. It is a figure (a) which shows the form which a protrusion is provided in the hole of a perforated plate, the figure (b) which shows the form which provides the protrusion only at the entrance of a passage, and the figure (c) which shows the form which forms the protrusion in a rib shape. .. It is a figure which shows the form which forms the hole of a perforated plate into a quadrangle. It is a figure (a), (b) which shows the method of manufacturing the heating element which has a spiral passage. It is a figure which shows the modification of the jig. It is a figure which shows the form in which a plurality of perforated plates and two engagement holes are formed on one plate. It is a perspective view which shows by partially breaking the heating unit which concerns on a modification. It is sectional drawing which shows the lower end side of a heating unit.

Next, an embodiment of the present invention will be described in detail with reference to the drawings as appropriate.
As shown in FIG. 1, the heating unit HU is a unit that heats water by induction heating, and is incorporated in, for example, a part of a pipe of a hot water supply facility HW. The heating unit HU includes a columnar heating element 1, an accommodating pipe 2 accommodating the heating element 1, and a coil unit 3 provided on the outer peripheral surface of the accommodating pipe 2.

The heating element 1 is a heating element that is induced and heated by a coil 31 described later in the coil unit 3, and has a plurality of passages 1A through which water can pass. The material of the heating element 1 may be any material as long as it is induced to be heated, and for example, stainless steel, iron, aluminum and the like can be used.

The accommodating pipe 2 is made of a material such as resin that is not induced to be heated, and is formed to have a length equal to or longer than the length of the heating element 1. As the material of the accommodating pipe 2, for example, engineering plastic, polyphenylene sulfide, or the like can be used.

The coil unit 3 includes a coil 31, a covering member 32 that covers the outer circumference and both ends of the coil 31, and a housing 33 that houses the coil 31 and the covering member 32. The coil 31 is, for example, a coil made of litz wire. A part of the housing 33, a part of the accommodating pipe 2, and a part of the heating element 1 are arranged inside the coil 31.

The coating member 32 is made of a material that is ferromagnetic but difficult to induce heating, such as ferrite. The covering member 32 suppresses leakage of magnetic flux generated in the coil 31. The housing 33 is made of a material such as resin that is not induced to be heated. Both ends of the heating element 1 and the accommodating pipe 2 are arranged so as to project from the housing 33.

The hot water supply facility HW includes the above-mentioned heating unit HU, as well as an upstream side pipe P1, an upstream side joint C1, and a downstream side joint C2. Here, "upstream" and "downstream" mean upstream / downstream of the flow of water flowing through the hot water supply facility HW.

The upstream side pipe P1 is arranged between a supply unit (not shown) for supplying water to the heating unit HU and the heating unit HU. The supply unit includes, for example, a water supply valve that allows or blocks the flow of water toward the heating unit HU.

The upstream side joint C1 connects the upstream side pipe P1 and the upstream end of the accommodating pipe 2. The upstream side joint C1 includes an upstream side temperature sensor C11 and an upstream side temperature fuse C12. The upstream temperature sensor C11 is a sensor that detects the temperature of water before passing through the heating element 1, and is arranged on the upstream side of the heating element 1.

The upstream thermal fuse C12 has a function of shutting off the current flowing through the coil 31 when the temperature on the inlet side of the heating element 1 exceeds a predetermined threshold value. The upstream thermal fuse C12 is arranged at a position corresponding to the upstream end of the heating element 1.

The downstream side joint C2 connects the downstream side pipe (not shown) and the downstream end of the accommodating pipe 2. Here, the downstream pipe is a pipe that allows water coming out of the heating unit HU to flow toward the faucet.

The downstream side joint C2 includes a downstream side temperature sensor C21 and a downstream side temperature fuse C22. The downstream temperature sensor C21 is a sensor that detects the temperature of the heated water after passing through the heating element 1, and is arranged on the downstream side of the heating element 1. The temperature of water before and after heating detected by the upstream temperature sensor C11 and the downstream temperature sensor C21 is used, for example, to control the current flowing through the coil 31.

The downstream thermal fuse C22 has a function of shutting off the current flowing through the coil 31 when the temperature on the outlet side of the heating element 1 exceeds a predetermined threshold value. The downstream thermal fuse C22 is arranged at a position corresponding to the downstream end of the heating element 1. Here, in the present embodiment, the two thermal fuses C12 and C22 are provided at both ends of the heating element 1, but the thermal fuses may be provided only at one end of either the upstream side or the downstream side of the heating element 1. Good.

As shown in FIG. 2A, the heating element 1 is configured by laminating a plurality of perforated plates 11. The perforated plate 11 is a disk having two planes parallel to each other, and has a plurality of regular hexagonal holes 11A arranged in a honeycomb shape. The passage 1A of the heating element 1 described above is formed by a plurality of holes 11A arranged in the axial direction of the heating element 1. Therefore, the holes 11A of the perforated plate 11 located at both ends of the heating element 1 are openings of the passage 1A.

The perforated plate 11 has a ring-shaped outer peripheral portion 11B and a plurality of compartments 11C extending along the periphery of each hole 11A.

The outer peripheral portion 11B has a recess 11D on the outer peripheral surface. The recess 11D is a portion used in the production of the heating element 1. The function of the recess 11D will be described in detail later.

The plurality of compartments 11C are integrally formed and connected to the inner peripheral surface of the outer peripheral portion 11B.

The outer diameter of the heating element 1 is preferably 20 mm or less. The reason is that if the outer diameter of the heating element 1 is increased, the magnetic field of the coil 31 does not sufficiently act on the compartment 11C around the passage 1A near the center of the heating element 1, and the heating element 1 This is because the water passing through the passage 1A near the center may not be efficiently heated. The outer diameter of the heating element 1 may be larger than 20 mm.

As shown in FIG. 2B, the dimension L1 in the predetermined direction of the partition portion 11C located between the two holes 11A arranged in the predetermined direction can be, for example, 0.2 mm, and is in the predetermined direction of the holes 11A. The dimension L2 can be, for example, 0.6 mm. When the experiment was conducted with the outer diameter of the heating element being 20 mm, the length of the heating element being 30 cm, L1 = 0.2 mm, L2 = 0.6 mm, the flow rate of water being 3 L / min, and the electric power being 1400 W, water at room temperature was used. Has been confirmed to be heated to 90 ° C. or higher.

Next, a method for manufacturing the heating element 1 will be described.
The method for manufacturing the heating element 1 mainly includes a first step, a second step, and a third step.
In the first step, the perforated plate 11 is manufactured by forming a plurality of holes 11A in the plate BD made of a material capable of induction heating. Specifically, a plurality of holes 11A corresponding to each of the plurality of perforated plates 11 are formed on one plate BD by etching. At this time, a plurality of holes 11A are formed in a regular hexagonal shape and arranged in a honeycomb shape. The outer shape and the recess 11D of each perforated plate 11 may be formed by etching or by punching by press working.

As shown in FIGS. 4A and 4B, in the second step, a plurality of perforated plates 11 are superposed in a state where the holes 11A of each perforated plate 11 communicate with each other. Specifically, in the second step, a plurality of perforated plates 11 are superposed using a cylindrical jig J.

The jig J has a cylindrical outer frame J1 and a rib-shaped guide J2 protruding from the inner peripheral surface of the outer frame J1. The guide J2 is a convex portion that fits into the concave portion 11D of the perforated plate 11, and extends from one end to the other end of the outer frame J1.

The operator stacks the perforated plate 11 in the outer frame J1 while aligning the recess 11D of the perforated plate 11 with the guide J2. As a result, the positions of the holes 11A of the perforated plates 11 can be matched, so that the holes 11A of the perforated plates 11 are aligned in the axial direction of the jig J to form the passage 1A (see FIG. 1). ..

In the third step, a plurality of superposed perforated plates 11 are joined by diffusion joining. As a result, the heating element 1 is manufactured. Here, diffusion bonding is a bonding in which the base metal is brought into close contact with each other, pressurized to the extent that plastic deformation does not occur as much as possible under temperature conditions below the melting point of the base metal, and the diffusion of atoms generated between the bonding surfaces is utilized. How to do it. As a result, since the plurality of perforated plates 11 can be joined without using an adhesive, it is possible to prevent the small holes 11A from being blocked by the adhesive.

Further, since the material itself of the perforated plate 11 is closely adhered and integrated, magnetic flux and heat can be satisfactorily passed in the laminating direction of the perforated plate 11. In particular, when the heating element 1 is arranged so as to project from both ends of the coil 31 as in the present embodiment (see FIG. 1), the portion of the heating element 1 near both ends of the coil 31 is other. The temperature is higher due to the influence of the magnetic force of the coil 31 as compared with the portion. Then, heat is transferred from the high temperature portion to the other portion by heat conduction, but since the plurality of perforated plates 11 are integrated by diffusion bonding, the heat is efficiently transferred to the other portion. Can be made to.

Based on the above, the following effects can be obtained in the present embodiment.
Since a heating element 1 having a plurality of passages 1A can be manufactured by superimposing a plurality of perforated plates 11 and joining them by diffusion bonding, the length of the heating element 1 can be set to an arbitrary size. Even a relatively long heating element 1 can be satisfactorily manufactured. Further, by joining the plurality of perforated plates 11 by diffusion joining, the materials of the perforated plates 11 are integrated with each other, so that the heat transfer property of the heating element 1 in the flow path direction is not impaired and heat transfer is performed with high efficiency. Can be done. Further, unlike the case where a plurality of perforated plates 11 are bonded with an adhesive, for example, the adhesive does not protrude into the holes 11A of the perforated plates 11, so that the flow of water in the passage 1A can be improved.

By forming a plurality of holes 11A by etching in the first step, the size of the holes 11A can be made very small, so that the outer diameter of the heating element 1 can be made small. Further, by reducing the outer diameter of the heating element 1 in this way, the action of the magnetic field of the coil 31 can be satisfactorily exerted on the partition portion 11C forming the passage 1A near the center of the heating element 1, so that heat is generated. The water flowing through the passage 1A near the center of the body 1 can be satisfactorily heated.

Since the plurality of holes 11A are formed in a regular hexagonal shape and arranged in a honeycomb shape, the rigidity of the heating element 1 can be increased and the shape of the holes 11A can be kept good.

The present invention is not limited to the above embodiment, and can be used in various forms as illustrated below. In the following description, members having substantially the same structure as that of the above embodiment are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5A, the heating element 1 may have a protrusion 1B on the inner peripheral surface of the passage 1A. Specifically, in this form, the heating element 1 has protrusions 1B formed at portions corresponding to each side of the regular hexagon in the passage 1A having a regular hexagonal opening. That is, six protrusions 1B are formed for one passage 1A. Each protrusion 1B is formed by forming a protrusion 11E on the inner peripheral surface of the hole 11A when the perforated plate 11 is manufactured in the first step described above.

By providing the protrusion 1B in the passage 1A of the heating element 1 in this way, the contact area of the heating element 1 with water can be increased to improve the heat transfer performance.

As shown in FIG. 5B, for example, the protrusion 1B can be provided at the entrance of the passage 1A of the heating element 1, that is, at the upstream end. In the first step, such a heating element 1 manufactures a perforated plate 11 having a protrusion 11E and a perforated plate 11 without the protrusion 11E, and in the second step, a plurality of perforated plates 11 without the protrusion 11E. After stacking the above, the perforated plate 11 having the protrusion 11E may be overlapped and the third step may be carried out.

According to this, since the protrusion 1B at the entrance of the passage 1A can suppress the entry of foreign matter into the passage 1A, the clogging of the passage 1A due to the foreign matter can be satisfactorily suppressed. Specifically, for example, as shown in FIG. 5B, even if a foreign matter FM having a shape close to a sphere flows, the foreign matter FM is caught by the tip of each protrusion 1B, so that it is shown in FIG. 5A. As described above, the partial FM1 of the foreign matter FM closes the circular range connecting the tips of the protrusions 1B, but the gap between the protrusions 1B is secured, so that water can pass through the gap.

Further, in this form, the protrusion 1B is formed in a wedge shape with a sharp tip. When the dimension L2 of the hole 11A is 0.6 mm, the length of the bottom surface of the protrusion 1B can be, for example, 0.1 mm, and the height of the protrusion 1B can be 0.15 mm.

By providing the protrusion 1B with a sharp tip in this way, when the solid matter formed by agglomerating the karuki contained in tap water collides with the protrusion 1B, the solid matter is crushed by the sharp tip of the protrusion 1B. Therefore, clogging of the passage 1A can be further suppressed.

The shape of the protrusion 1B is not limited to the wedge shape, and may be any shape. Further, the number of protrusions 1B for one passage 1A may be any number.

Further, the protrusion 1B may extend in a rib shape from the entrance to the exit of the passage 1A, for example, as shown in FIG. 5C. In such a heating element 1, a plurality of perforated plates 11 having protrusions 11E are manufactured in the first step, and in the second step, a plurality of perforated plates 11 having protrusions 11E are laminated, and then the third step is performed. It should be carried out. That is, the rib-shaped protrusions 1B may be formed by diffusion-bonding the plurality of protrusions 11E.

According to this, clogging of the passage 1A can be suppressed, and the contact area between the heating element 1 and water can be further increased as compared with the form of FIG. 5B, so that the heat transfer performance can be further improved. be able to.

In the above embodiment, the hole 11A is a regular hexagon, but the present invention is not limited to this, and the shape of the hole may be another shape, for example, a circle or another polygon. However, in order to make the width of the portion around the hole (partition portion 11C) constant, it is preferable to use a polygon such as the above-mentioned regular hexagonal hole 11A or the quadrangular hole 11F as shown in FIG.

In the above embodiment, the passage 1A is formed in a linear shape along the axial direction of the heating element 1, but the present invention is not limited to this. For example, as shown in FIG. 7B, the passage 1A is formed in a spiral shape. May be formed in. In the second step, in such a heating element 1, the holes 11A may be arranged in a spiral shape by superimposing the plurality of adjacent perforated plates 11 in a shifted phase.

Specifically, for example, as shown in FIG. 7A, a jig J having a spiral guide J3 may be used in the second step. By superimposing the perforated plate 11 on the spiral guide J3 while aligning the recess 11D of the perforated plate 11, the perforated plate 11 can be overlapped while shifting the phase.

According to this form, the water passing through the spiral passage 1A can be evenly contacted with the inner wall of the passage 1A, so that the heat from the heating element 1 can be efficiently transferred to the water flowing through the passage 1A. Further, by making the passage 1A spiral, for example, the length of the passage 1A relative to the length of the heating element 1 can be increased as compared with the case where the passage is formed in a linear shape, so that the water flowing through the passage generates heat. The heat from the body can be transferred efficiently. The method of arranging the holes 11A in a spiral shape is not limited to the method described above. For example, as shown in FIG. 3, in the first step, a plurality of perforated plates 11 in which the recesses 11D are out of phase are manufactured, and a plurality of perforated plates 11 in which the recesses 11D are out of phase are used as a jig shown in FIG. It may be a method of laminating using J.

The jig for laminating the perforated plate 11 is not limited to the jig J as described above, and may be, for example, two rod-shaped jigs JA as shown in FIG. In this case, in the first step, a plurality of holes 11A are formed in one plate BD, and two arc-shaped slits SL are formed along the outer peripheral surface of the perforated plate 11. As a result, the perforated plate 11 is formed in a state of being connected to the surplus portion BD2 of the plate BD via the two connecting portions BD1.

Further, two engaging holes BD3 that engage with the jig JA are formed in the surplus portion BD2 of the plate BD, that is, the portion where the perforated plate 11 is not formed. Then, in the second step, the operator stacks a plurality of plate BDs while inserting each jig JA into each engagement hole BD3 of the plate BD.

After that, in the third step, a plurality of plate BDs are joined by diffusion joining. Finally, the heating element 1 is manufactured by cutting the connecting portion BD1 by a method such as wire cutting.

As shown in FIG. 9, when a plurality of perforated plates 11 are formed on one plate BD, two engagement holes BD3 may be provided on one plate BD. In this method, since a plurality of heating elements 1 can be obtained by performing the first step, the second step, and the third step once, it is suitable for mass production.

Further, in the form of FIG. 8, the jig JA is a columnar shape and the engaging hole BD3 is a round hole. For example, the jig is a polygonal rod and the engaging hole is a polygon corresponding to the shape of the jig. It may be a hole of. In this case, the jig may be one and the engagement hole may be one.

Further, when the passage 1A is spirally formed by the method shown in FIG. 8, the perforated plate 11 may be formed so that the phase of each hole 11A of the perforated plate 11 is shifted for each plate BD in the first step. .. In this case, if the plate BDs are laminated while aligning the engaging holes BD3 with each jig JA, the angle of the perforated plate 11 changes sequentially, so that the passage 1A can be made into a spiral shape.

In the above embodiment, the guides J2 and J3 are formed in a convex shape, but the present invention is not limited to this, and the guide may have a concave shape. In this case, a convex portion that engages with the concave guide may be provided on the outer peripheral surface of the perforated plate.

In the above embodiment, each hole 11A of the perforated plate 11 is formed by etching, but the present invention is not limited to this, and for example, each hole of the perforated plate may be formed by press working.

It is conceivable that the coil is cooled by air cooling, but there is a possibility that the coil cannot be cooled efficiently by air cooling. In order to solve such a problem, for example, the heating unit HU2 shown in FIG. 10 may be adopted as the heating unit. The heating unit HU2 includes a heating element 1, a storage pipe 2, a coil 31 and a covering member 32 having the same functions as those in the above embodiment, and also includes a preheating flow path forming member 40. The preheating flow path forming member 40 is a member for forming a preheating flow path 41 for flowing water along the outer circumference of the coil 31.

The preheating flow path forming member 40 includes a first housing 50 and a second housing 60. The first housing 50 has a cylindrical first outer peripheral wall 51 centered on a heating element 1.

The second housing 60 is a cylindrical second outer peripheral wall 61 centered on the heating element 1, and has a second outer peripheral wall 61 having a diameter larger than that of the first outer peripheral wall 51. The second outer peripheral wall 61 is arranged at a distance from the first outer peripheral wall 51 to form a preheating flow path 41 with the first outer peripheral wall 51.

The second outer peripheral wall 61 has a water supply port 61A for supplying water to the preheating flow path 41 and a drainage port 61B for discharging water from the preheating flow path 41. The water supply port 61A and the drainage port 61B are separated from each other in the axial direction along the central axis of the second outer peripheral wall 61. The water supply port 61A and the drainage port 61B are arranged at the same position in the circumferential direction of the second outer peripheral wall 61.

Around the water supply port 61A, a cylindrical first connection portion 62 for connecting pipes is provided. A cylindrical second connecting portion 63 for connecting pipes is provided around the drain port 61B. The first connecting portion 62 and the second connecting portion 63 project from the outer peripheral surface of the second outer peripheral wall 61.

The first connection portion 62 is connected to a supply portion (not shown) for supplying water to the heating unit HU via a pipe (not shown). The second connecting portion 63 is connected to the accommodating pipe 2 via a pipe (not shown) and a first cap 70 described later. As a result, the preheating flow path 41 is connected to the passage 1A of the heating element 1, and the water supplied to the preheating flow path 41 passes through the passage 1A of the heating element 1 after passing through the preheating flow path 41. Has been done.

Further, the second housing 60 has a rib 64 protruding from the inner peripheral surface of the second outer peripheral wall 61. The rib 64 is formed in a spiral shape between the water supply port 61A and the drainage port 61B. As a result, the preheating flow path 41 is spirally formed with respect to the first outer peripheral wall 51.

Further, the rib 64 is separated from the first outer peripheral wall 51 of the first housing 50. As a result, the water passing through the preheating flow path 41 can be brought into contact with substantially the entire outer peripheral surface of the first housing 50 in the range between the water supply port 61A and the drainage port 61B.

Between each end of the first housing 50 and each end of the second housing 60 is sealed with another member. Since the heating unit HU2 has a substantially symmetrical shape with respect to the center in the axial direction, the structure for sealing the end portion of the first housing 50 and the end portion of the second housing 60 will be described below in the axial direction. The description will be made on behalf of the lower end side of the above, and the description of the other end side will be omitted.

As shown in FIG. 11, the heating unit HU2 includes a first cap 70 and a second cap 80 on the lower end side in the axial direction. The first cap 70 is a member that connects the accommodating pipe 2 and the first housing 50.

The first cap 70 has a cylindrical first connecting portion 71 connected to the first housing 50, a cylindrical second connecting portion 72 connected to the accommodating pipe 2, and an opening on the lower end side of the first housing 50. It has a wall 73 for closing the wall 73, a piping portion 74 for passing water, and a cylindrical portion 75. The first connecting portion 71 is attached to the lower end portion of the first housing 50 in a state where the inner peripheral surface is in contact with the outer peripheral surface of the first housing 50. Specifically, the female screw portion formed on the inner peripheral surface of the first connecting portion 71 meshes with the male screw portion formed on the outer peripheral surface of the first housing 50. The first connecting portion 71 and the first housing 50 are sealed with ring-shaped sealing members S1 and S2.

The second connecting portion 72 is fitted to the outer peripheral surface of the accommodating pipe 2. The wall 73 connects the first connecting portion 71 and the second connecting portion 72. The space between the wall 73 and the lower end of the first housing 50 is sealed with a ring-shaped sealing member S3.

The outer diameter of the piping portion 74 is smaller than that of the second connecting portion 72, and extends from the second connecting portion 72 to the side opposite to the accommodating pipe 2. The piping portion 74 is connected to the second connecting portion 63 of the second housing 60 via a pipe (not shown).

The cylindrical portion 75 is a cylindrical portion having a smaller diameter than the first connecting portion 71 and a larger diameter than the second connecting portion 72. The cylindrical portion 75 extends from the wall 73 on the side opposite to the first housing 50.

The second cap 80 includes a cylindrical outer cylinder portion 81 and an inner cylinder portion 82 connected to the second housing 60, a cylindrical cap connecting portion 83 connected to the cylindrical portion 75 of the first cap 70, and the like. It has an outer cylinder portion 81, an inner cylinder portion 82, and a wall 84 that connects the cap connecting portion 83. The outer cylinder portion 81 sandwiches the lower end portion of the second housing 60 with the inner cylinder portion 82.

Specifically, at the lower end of the second outer peripheral wall 61 of the second housing 60, a bulging portion 65 that bulges outward in the radial direction from the outer peripheral surface of the second outer peripheral wall 61 is formed. The bulging portion 65 is formed with a recess 65A into which the outer cylinder portion 81 of the second cap 80 is inserted. The inner surface of the recess 65A and the outer cylinder portion 81 are sealed with ring-shaped sealing members S4 and S5.

The inner cylinder portion 82 is arranged between the second housing 60 and the first connecting portion 71 of the first cap 70 in the radial direction. The outer peripheral surface of the inner cylinder portion 82 is a conical tapered surface. Specifically, the outer peripheral surface of the inner cylinder portion 82 is inclined so as to move away from the second housing 60 as the distance from the wall 84 increases.

The inner cylinder portion 82 and the first connecting portion 71 are sealed with a ring-shaped sealing member S6. The wall 84 and the second housing 60 are sealed with a ring-shaped sealing member S7. The space between the wall 84 and the wall 73 of the first cap 70 is sealed with a ring-shaped sealing member S8.

The cap connecting portion 83 is attached to the cylindrical portion 75 in a state where the inner peripheral surface is in contact with the outer peripheral surface of the cylindrical portion 75 of the first cap 70. Specifically, the female screw portion formed on the inner peripheral surface of the cap connecting portion 83 meshes with the male screw portion formed on the outer peripheral surface of the cylindrical portion 75.

Next, the action and effect of the heating unit HU2 will be described.
As shown in FIG. 10, when water is supplied into the preheating flow path 41 from the water supply port 61A of the second housing 60, the water flows on the outer peripheral surface of the second housing 60 by the spiral preheating flow path 41. It rotates in a spiral and flows. As a result, the heat generated in the coil 31 is absorbed by the water, so that the coil 31 is cooled and the water is preheated.

The water that has passed through the preheating flow path 41 enters the accommodation pipe 2 from the drain port 61B of the second housing 60 via a pipe (not shown) and the first cap 70. The water that has entered the accommodation pipe 2 passes through each passage 1A of the heating element 1. As a result, the water preheated in the preheating flow path 41 is further heated in each passage 1A of the heating element 1 and discharged from a faucet (not shown).

As described above, according to this form, the following effects can be obtained.
Since the coil 31 can be cooled by the water passing through the preheating flow path 41, the coil 31 can be cooled more efficiently than, for example, air cooling. Further, since the water passing through the preheating flow path 41 takes the heat of the coil 31 and then is heated in the passage 1A of the heating element 1, the water can be heated efficiently.

Since the preheating flow path 41 is formed between the first housing 50 that covers the coil 31 and the second housing 60 that covers the first housing 50, water is applied to the entire circumference of the first outer peripheral wall 51 of the first housing 50. The water that can flow through the preheating flow path 41 can efficiently absorb the heat of the coil 31.

Since the preheating flow path 41 is formed spirally with respect to the first outer peripheral wall 51, the length of the preheating flow path 41 can be increased, and the heat of the coil 31 can be increased by the water passing through the preheating flow path 41. It can be absorbed efficiently.

Since the water supply port 61A and the drainage port 61B are separated in the axial direction, the length of the preheating flow path 41 can be increased as compared with the case where the water supply port and the drainage port are arranged at the same position in the axial direction, for example.

By separating the rib 64 from the outer peripheral surface of the first housing 50, the water passing through the preheating flow path 41 can be brought into contact with the entire outer peripheral surface of the first housing 50. Therefore, the water passing through the preheating flow path 41 of the coil 31 It can absorb heat efficiently.

In the form of FIG. 10, the rib 64 is provided in the second housing 60, but the present invention is not limited to this, and the rib 64 may not be provided. Further, the preheating flow path is not limited to the flow path formed by the two housings. For example, the flow path in the pipe may be used as a preheating flow path by winding a pipe through which water passes around the outer peripheral surface of the first housing.

Further, the heating element through which water passes through the preheating flow path may have any structure as long as it has a passage, and may be manufactured by any manufacturing method. For example, a heating element having a passage may be manufactured by drilling a columnar metal rod.

In the embodiment of FIG. 10, the water supply port 61A and the drainage port 61B are arranged at the same position in the circumferential direction of the second outer peripheral wall 61, but the present invention is not limited to this, and even if they are arranged at different positions in the circumferential direction. Good.

Each element described in the above-described embodiment and modification may be arbitrarily combined and implemented.

Claims

A method for manufacturing a heating element that is induced and heated by a coil.
The first step of manufacturing a perforated plate by forming a plurality of holes in a plate made of a material that can be induced and heated, and
The second step of superimposing the plurality of the perforated plates in a state where the holes of the perforated plates communicate with each other,
A method for manufacturing a heating element, which comprises a third step of joining a plurality of superposed perforated plates by diffusion bonding.
The method for manufacturing a heating element according to claim 1, wherein a plurality of holes are formed in the plate by etching in the first step.
The method for manufacturing a heating element according to claim 1 or 2, wherein a protrusion is formed on the inner peripheral surface of the hole in the first step.
The method for manufacturing a heating element according to any one of claims 1 to 3, wherein in the first step, the plurality of holes are formed in a regular hexagonal shape and arranged in a honeycomb shape.
The second step according to any one of claims 1 to 4, wherein the holes are arranged in a spiral shape by superimposing the plurality of adjacent perforated plates in a shifted phase. Manufacturing method of heating element.
A heating element that is induced and heated by a coil.
Has multiple passages through which water can pass
A heating element having a protrusion on the inner peripheral surface of the passage.
The heating element according to claim 6, wherein the protrusion is provided at least at the entrance of the passage.
The heating element according to claim 6 or 7, wherein the protrusion extends in a rib shape from the entrance to the exit of the passage.
A heating element that is induced and heated by a coil.
Has multiple passages through which water can pass
A heating element characterized in that the plurality of passages have regular hexagonal openings and the openings are arranged in a honeycomb shape.
A heating element that is induced and heated by a coil.
Has multiple passages through which water can pass
The heating element is characterized in that the passage is formed in a spiral shape.
A heating unit including the heating element according to any one of claims 6 to 10.
A coil that induces heating the heating element and
A preheating flow path forming member for forming a preheating flow path for flowing water along the outer circumference of the coil is provided.
The preheating flow path is connected to the passage of the heating element,
A heating unit characterized in that water supplied to the preheating flow path is configured to pass through the passage of the heating element after passing through the preheating flow path.
The preheating flow path forming member is
A first housing having a cylindrical first outer peripheral wall centered on the heating element, and
A second outer peripheral wall having a diameter larger than that of the first outer peripheral wall, and by being arranged at a distance from the first outer peripheral wall, the preheating flow path is formed between the first outer peripheral wall and the first outer peripheral wall. 2. The heating unit according to claim 11, further comprising a second housing having an outer peripheral wall.
The heating unit according to claim 12, wherein the preheating flow path is formed in a spiral shape with respect to the first outer peripheral wall.
The second housing has ribs protruding from the inner peripheral surface of the second outer peripheral wall.
The heating unit according to claim 13, wherein the ribs are formed in a spiral shape.