JP6856668B2 - Heater device - Google Patents

Description

The present disclosure relates to a heater device for fluid heating.

As a heater for washing hot water, a tubular heater made of a ceramic body is inserted into a casing, and a rod-shaped core rod is inserted inside the heater. Then, a heater device has been proposed in which a spiral guide is provided on the outer peripheral surface of the core rod to allow a fluid to flow between the tubular heater and the core rod to heat the core rod (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2011-80352

The heater device of the present disclosure includes a tubular ceramic body having a longitudinal direction and a resistor embedded in the ceramic body, and heats a fluid flowing along the longitudinal direction inside the ceramic body. It is a thing. A spiral convex portion is provided on the inner wall of the ceramic body , and the height of the spiral convex portion at the end portion on the front end side of the ceramic body is at the end portion on the rear end side of the ceramic body. Higher than height .

It is a perspective view which shows an example of embodiment of a heater device. It is a schematic vertical sectional view cut along line II-II shown in FIG. It is a schematic vertical sectional view which shows the other example of embodiment of a heater device. It is a schematic vertical sectional view which shows the other example of embodiment of a heater device. It is a schematic vertical sectional view which shows the other example of embodiment of a heater device. Is a perspective view showing another example of the embodiment of the heater device. It is a schematic vertical sectional view cut along line VII-VII shown in FIG. It is a schematic vertical sectional view which shows the other example of embodiment of a heater device. It is a schematic vertical sectional view which shows the other example of embodiment of a heater device. It is a schematic vertical sectional view which shows the other example of embodiment of a heater device. It is a schematic vertical sectional view which shows the other example of embodiment of a heater device.

In recent years, miniaturization of heater devices has been required, and improvement of heating efficiency is required for such heater devices.

If a spiral guide is provided on the outer peripheral surface of the core rod, fluid will flow around the core rod along the guide, apparently lengthening the flow path and improving heating efficiency, but the core rod does not have a heat generating resistor and the core. Since the rod itself does not generate heat, there was room for improvement in terms of improving heating efficiency.

The heater device of the present disclosure includes a tubular ceramic body having a longitudinal direction and a resistor embedded inside the ceramic body, and heats a fluid flowing along the longitudinal direction inside the ceramic body. is there. Then, a spiral convex portion is provided on the inner wall of the ceramic body. With such a configuration, a part of the fluid entering through one opening of the ceramic body flows along the spiral convex portion of the inner wall of the ceramic body, and the length of the flow path along the heating surface is apparently long. become longer. Further, when the fluid hits the wall of the spiral convex portion, turbulence is likely to occur, and the heat transfer property is improved. Therefore, the heating efficiency can be improved.

Hereinafter, embodiments of the heater device will be described with reference to the drawings.

FIG. 1 is a perspective view showing an example of an embodiment of the heater device, and FIG. 2 is a schematic vertical cross-sectional view taken along the line II-II shown in FIG.

The heater device 1 shown in FIGS. 1 and 2 includes a tubular ceramic body 2 having a longitudinal direction and a resistor 3 embedded inside the ceramic body 2, and the inside of the ceramic body 2 is along the longitudinal direction. It heats the flowing fluid. A spiral convex portion 21 is provided on the inner wall of the ceramic body 2.

The heater device 1 allows fluids such as liquids, gases and powders to be heated to pass inside and outside the ceramic body 2 along the longitudinal direction, and heats the inner wall and the outer wall of the ceramic body 2 if necessary. It heats objects in contact with each other.

The ceramic body 2 is a tubular member having a length direction. Examples of the tubular shape include a cylindrical shape and a square tubular shape. In the heater device 1 shown in the figure, the ceramic body 2 has a cylindrical shape. When the ceramic body 2 has a cylindrical shape, the dimensions can be set, for example, to have a total length of 40 to 150 mm in the length direction, an outer diameter of 4 to 30 mm, and an inner diameter of 1 to 28 mm.

The ceramic body 2 is made of an insulating ceramic material. Examples of the insulating ceramic material include alumina, silicon nitride or aluminum nitride. Aluminum nitride can be used in terms of excellent thermal conductivity, and alumina can be used in terms of oxidation resistance and ease of manufacture.

A resistor 3 is embedded inside the ceramic body 2. The resistor 3 heats the ceramic body 2 by generating heat when an electric current flows. Although not shown, the resistor 3 has a folded-back portion (meandering portion) provided along the circumferential direction while being repeatedly folded back in the length direction. Then, one end of the resistor 3 is electrically connected to one of the pair of drawers 4 described later, and the other end is electrically connected to the other of the pair of drawers 4 described later.

The resistor 3 is made of a conductor mainly composed of a metal having a high melting point such as tungsten (W), molybdenum (Mo) or rhenium (Re). The dimensions of the resistor 3 can be set, for example, to have a width of 0.3 to 2 mm, a thickness of 0.01 to 0.1 mm, and a total length of 500 to 5000 mm. These dimensions are appropriately set in consideration of the heat generation temperature of the resistor 3, the voltage applied to the resistor 3, and the like.

The drawer 4 is for electrically connecting the resistor 3 and the electrode pad 5 described later, and is provided in pairs corresponding to one end and the other end of the resistor 3. The drawer portion 4 is made of the same material as the resistor 3. When the cross section of the drawer portion 4 is circular, the diameter is, for example, 1 to 5 mm.

An electrode pad 5 is provided on the outer wall which is the outer peripheral surface of the ceramic body 2, and the electrode pad 5 is electrically connected to the drawer portion 4. The electrode pads 5 serve as portions for joining the lead terminals 7 described later, and are located at two opposing locations on the outer wall on the rear end side of the ceramic body 2 (two locations located on the diameter when viewed in cross section). Each of the drawers 4 is electrically connected to the drawer 4 and is provided.

The electrode pad 5 is made of, for example, tungsten, molybdenum, or the like, and may be made of the same metal material as the resistor 3 and the drawer portion 4, or may be made of a different metal material. The dimensions of the electrode pad 5 can be set, for example, to have a length of 5 to 10 mm, a width of 5 to 10 mm, and a thickness of 0.01 to 0.1 mm.

A lead terminal 6 is bonded to the electrode pad 5 using a bonding material. One end of the lead terminal 6 is joined to the electrode pad 5, and the other end is connected to an external power source or the like. Examples of the cross-sectional shape of the lead terminal 6 include a circular shape, an elliptical shape, and a rectangular shape. When the lead terminal 6 has a circular cross section, the diameter is, for example, 0.5 to 2.0 mm. Further, as the bonding material, for example, a brazing material such as silver brazing or silver copper brazing material or a solder such as Sn (tin) -Ag (silver) -Cu (copper) can be used.

A spiral convex portion 21 is provided on the inner wall of the ceramic body 2. As a result, a part of the fluid entering through one opening of the ceramic body 2 flows along the spiral convex portion 21 of the inner wall of the ceramic body 2, so that the length of the flow path along the heating surface is apparently long. .. Further, when the fluid hits the wall of the spiral convex portion 21, turbulence is likely to occur, and the heat transfer property is improved. Therefore, the heating efficiency can be improved, and a desired temperature can be reached even with a short flow path.

Here, when the inner diameter of the ceramic body 2 is, for example, 5 to 15 mm, the width w of the spiral convex portion 21 (width in the left-right direction in FIG. 2) is, for example, 1 to 3 mm, and the height of the spiral convex portion 21 is high. The height t (height in the vertical direction in FIG. 2) is, for example, 0.5 to 3 mm. Further, the distance d between adjacent convex portions when viewed from the cut surface of the spiral convex portion 21 is 2 to 10 times the width w of the spiral convex portion 21.

When the core rod 7 is not inserted as compared with the case where the core rod 7 is inserted, the width w of the spiral convex portion 21 may be the same, but the height t of the spiral convex portion 21 is It may be expensive. It is effective in that turbulence is more likely to occur.

As the cross-sectional shape of the spiral convex portion 21, a quadrangular shape, a triangular shape, a semicircular shape, or the like can be adopted, but in the example shown in the figure, the cross-sectional shape is quadrangular. As shown in FIG. 2, when the cross-sectional shape of the spiral convex portion 21 is quadrangular, the spiral convex portion 21 rises vertically from the inner wall of the ceramic body 2, so that the fluid is spiral convex. A turbulent flow is more likely to occur on the wall surface of the portion 21, the heating efficiency can be improved, and a desired temperature can be reached even with a shorter flow path.

Further, as shown in FIG. 3, the spiral convex portion 21 may have a plurality of notch-shaped portions 20. Further, the plurality of notch-shaped portions 20 may be arranged aligned along a straight line in the longitudinal direction. As a result, the fluid that intends to stay at the boundary portion between the spiral convex portion 21 and the inner wall surface of the ceramic body 2, that is, the corner portion easily flows through the notch-shaped portion 20, and the heating efficiency is improved.

The notch-shaped portion 20 is a portion where a part of the spiral convex portion 21 is interrupted and is flush with the inner wall of the ceramic body 2, or a part of the spiral convex portion 21 is another portion. It is the part that is lower than. The circumferential length of the notch-shaped portion 20, that is, the circumferential length of the portion along the inner wall of the ceramic body 2, is set to, for example, 1 to 3 mm.

Further, as shown in FIG. 4, when the spiral convex portion 21 has a plurality of notch-shaped portions 20, the plurality of notch-shaped portions 20 are not aligned along a straight line in the longitudinal direction. It may be arranged. As a result, in addition to making it difficult for the fluid to stay at the boundary portion between the spiral convex portion 21 and the inner wall surface of the ceramic body 2, that is, the corner portion, the fluid passing through the notch-shaped portion 20 is subjected to the next spiral convex portion. The wall surface of the portion 21 is more likely to generate turbulent flow, and the heat transfer property is improved. The displacement of the notch-shaped portions 20 adjacent to each other in the longitudinal direction in the circumferential direction may be at least to the extent that they do not overlap in the longitudinal direction, in other words, the notch-shaped portions 20 may be displaced by one or more.

Further, as shown in FIG. 5, the height t1 at the distal end side of the ceramic body 2 of the spiral convex portion 21 is higher than the height t2 at the rear end side of the ceramic body 2. May be good.

Generally, it is necessary to provide a space for power supply on the rear end side of the ceramic body 2, and it is not necessary to secure such a space on the front end side of the ceramic body 2, so that the front end side of the ceramic body 2 is The resistor 3 can be embedded in a larger area. Therefore, the ceramic body 2 often generates heat on the tip side. Then, for example, as shown by an arrow in the figure, the fluid is flowed so that the opening on the rear end side of the ceramic body 2 is the inlet, that is, the upstream side, and the opening on the front end side of the ceramic body 2 is the outlet, that is, the downstream side. .. As a result, it is possible to reduce the application of thermal shock to the ceramic body 2 particularly on the inlet side due to a sudden temperature change due to the inflow of fluid.

Here, the spiral convex portion 21 is located on the downstream side because the height t1 at the end portion of the ceramic body 2 on the distal end side is higher than the height t2 at the end portion on the rear end side of the ceramic body 2. The surface area of the heating surface increases on the tip side of a certain ceramic body 2. Therefore, the heating efficiency is further improved.

Further, as shown in FIG. 6 which is a perspective view showing another example of the embodiment of the heater device and FIG. 7 which is a schematic vertical cross-sectional view taken along the line VII-VII shown in FIG. 6, the heater device 1 is a ceramic body. The core rod 7 may be inserted into the space inside the 2. As a method of narrowing the space inside the ceramic body 2, that is, the flow path, a method of reducing the diameter of the ceramic body 2 can be mentioned, but in consideration of ease of manufacture, the core is in the space inside the ceramic body 2. The rod 7 may be inserted. As a result, the space inside the ceramic body 2, that is, the flow path is narrowed, so that the flow velocity of the fluid is increased, and the total amount of heat transferred to the fluid can be further increased. Further, since the fluid can flow closer to the inner wall which is the heating surface of the ceramic body 2, the fluid can be heated faster, the heating efficiency can be improved, and the desired temperature can be reached even with a shorter flow path.

The cross-sectional shape of the core rod 7 is preferably similar to the cross-sectional shape of the inner wall of the ceramic body 2. Further, the diameter of the core rod 7 when the cross-sectional shape of the inner wall of the ceramic body 2 is circular, in other words, the cross-sectional shape of the ceramic body 2 is annular and the cross-sectional shape of the core rod 7 is circular. For example, it is set to 1 to 10 mm, but it is preferable that the diameter is, for example, 30% or more of the circular diameter of the inner wall of the ceramic body 2.

Further, as shown in FIG. 8, the cross-sectional area of the space surrounded by the inner wall of the ceramic body 2 and the core rod 7 may be smaller on the front end side than on the rear end side of the ceramic body 2. As such an example, FIG. 8 shows an example in which the diameter of the core rod 7 gradually increases from the rear end side to the front end side of the ceramic body 2. As a result, the flow velocity becomes faster on the tip side, that is, the downstream side of the ceramic body 2, and the heating efficiency is further improved.

The diameter of the core rod 7 at the opening on the front end side of the ceramic body 2 is set to 1.1 to 2 times the diameter of the core rod 7 at the opening on the rear end side of the ceramic body 2.

Further, as shown in FIGS. 9 and 10, the height of the core rod 7 gradually increases from the rear end side to the tip side of the ceramic body 2 at the portion corresponding to the rear end side of the ceramic body 2. It may have an annular convex portion 71, 72. Here, the annular convex portion 71 shown in FIG. 9 has a shape in which the thickness gradually increases from the rear end side of the ceramic body 2 on the upstream side toward the tip side on the downstream side, that is, a so-called solid shape. The annular convex portion 72 shown in No. 10 has a shape in which the thickness is constant and the diameter expands from the rear end side of the ceramic body 2 on the upstream side toward the tip side on the downstream side, that is, a so-called funnel shape. As a result, the inflowing fluid easily flows to the inner wall of the ceramic body 2, and turbulence is likely to occur. Therefore, the heating efficiency is further improved.

As shown in FIGS. 9 and 10, for example, a tube 8 is connected to the ceramic body 2, and a fluid is supplied through the tube 8. The arrow shown in the figure shows how the fluid flows toward the inner wall of the ceramic body 2.

The height of the annular protrusions 71 and 72 is the distance between the outer peripheral surface of the core rod 7 excluding the annular protrusions 71 and 72 and the inner wall of the ceramic body 2, where the distance on one side is, for example, 0.5 to 0. It is multiplied by 8.8.

Further, as shown in FIG. 11, the spiral convex portion 21 and the core rod 7 may be in contact with each other. An example of such a method is a method of thickening the core rod 7. As a result, the heat of the ceramic body 2 is transferred to the core rod 7, and the heat can be transferred to the fluid from both the inner wall of the ceramic body 2 and the outer peripheral surface of the core rod 7, so that the heating efficiency is further improved and a short flow is achieved. The desired temperature can be reached even on the road.

When the spiral convex portion 21 and the core rod 7 do not come into contact with each other, it is preferable to use a material having a low thermal conductivity for the core rod 7 so as not to withdraw heat as much as possible. Specifically, a ceramic material such as stainless steel or alumina can be used.

On the other hand, when the spiral convex portion 21 and the core rod 7 come into contact with each other, the core rod 7 is made of a material having high thermal conductivity so that the core rod 7 also functions as a heat source in addition to the inner wall of the ceramic body 2. It is good to use a thing. Specifically, a high thermal conductive metal such as aluminum or copper can be used.

Next, a method of manufacturing the heater device 1 of the present embodiment will be described.

An example in which the ceramic body 2 is made of alumina ceramics will be described.

First, _{an alumina ceramic green sheet containing Al 2} O ₃ as a main component and _{adjusted so that SiO 2} , CaO, MgO, and ZrO ₂ are within 10% by mass in total is produced.

Then, a predetermined conductor pattern serving as the resistor 3 is formed on the surface of the alumina ceramic green sheet. Examples of the method for forming the resistor 3 include a screen printing method, a transfer method, a resistor burying method, a method of forming a metal foil by an etching method, and a method of forming a nichrome wire in a coil shape and burying the resistor 3. However, forming by the screen printing method is easy to use from the viewpoint of stability in terms of quality and suppression of manufacturing cost.

The electrode pad 5 is formed in a predetermined pattern shape on the surface of the alumina ceramic green sheet opposite to the surface on which the resistor 3 is formed, in the same manner as in the formation of the resistor 3.

Further, the alumina ceramic green sheet is subjected to hole processing for providing a drawer portion 4 for electrically connecting the resistor 3 and the electrode pad 5, and filling with a conductor paste for forming a through-hole conductor.

As the through-hole conductors of the resistor 3, the electrode pad 5, and the drawer portion 4, a conductive paste containing a refractory metal such as tungsten, molybdenum, or rhenium as a main component can be used.

On the other hand, a cylindrical alumina ceramic molded body is molded by extrusion molding. Here, the spiral convex portion 21 provided on the inner wall of the ceramic body 2 is obtained by providing a concave portion on the inner mouthpiece of the extrusion molding machine and performing extrusion molding while rotating it on the circumference. Alternatively, the alumina-based ceramic green sheet may be cut into long strips and spirally adhered to the inner wall of the molded body. Further, after sintering the molded body described later, the coil-shaped member may be brought into close contact with the inner wall of the ceramic body 2.

Then, the above-mentioned alumina ceramic green sheet is wound around this cylindrical alumina ceramic molded body. At this time, by applying an adhering liquid in which alumina ceramics having the same composition are dispersed and adhering them to each other, it is possible to obtain an alumina-based integrally molded body which becomes a ceramic body 2 in which a resistor 3 is embedded.

By firing the alumina-integrated molded body thus obtained in a reducing atmosphere (nitrogen atmosphere) at 1500 to 1600 ° C., the alumina-based integrally molded body shrinks, and the ceramic body 2 which is an alumina-based integrally sintered body is produced. Can be made.

Further, as a method of providing the notch-shaped portion 20 in the spiral convex portion 21 provided on the inner wall of the ceramic body 2, a process of removing the spiral convex portion 21 linearly in the axial direction of the ceramic body 2 by machining processing is performed. it can. Further, by using a special tool, it is possible to process and remove every other spiral convex portion 21 in the axial direction of the ceramic body 2.

Next, the electrode pad 5 formed on the ceramic body 2 is plated as a base for forming the feeding portion. Nickel plating, gold plating, tin plating and the like are generally used for plating. As the plating treatment method, it is advisable to select a treatment method such as electroless plating, electrolytic plating, or barrel plating according to the purpose. Then, the lead terminal 6 made of nickel is soldered onto the pad.

Further, as a method of inserting the core rod 7 inside the ceramic body 2 when the core rod 7 is inserted inside the ceramic body 2, a casing is arranged outside the ceramic body 2, and the core rod 7 is inserted into the casing. It should be fixed.

Further, as a method of providing the annular convex portion 71 at the portion of the core rod 7 corresponding to the end portion on the rear end side of the ceramic body 2, a method of integrally processing the core rod 7 and the annular convex portion 71 may be used. , A method in which the core rod 7 and the annular convex portion 71 are separately manufactured and joined with an adhesive or the like may be used.

The heater device 1 of the present embodiment can be obtained by the above method.

1: Heater device 2: Ceramic body 21: Spiral convex portion 20: Notch-shaped portion 3: Resistor 4: Drawer portion 5: Electrode pad 6: Lead terminal 7: Core rod 71, 72: Circular convex portion 8 :tube

Claims (8)

A heater device comprising a tubular ceramic body having a longitudinal direction and a resistor embedded inside the ceramic body, and heating a fluid flowing along the longitudinal direction inside the ceramic body. A spiral convex portion is provided on the inner wall of the ceramic body , and the height of the spiral convex portion at the end portion on the front end side of the ceramic body is higher than the height at the end portion on the rear end side of the ceramic body. A heater device characterized by being expensive. 1. The spiral convex portion has a plurality of notch-shaped portions, and the plurality of notch-shaped portions are arranged so as to be aligned along a straight line in the longitudinal direction. The heater device according to. The claim is characterized in that the spiral convex portion has a plurality of notch-shaped portions, and the plurality of notch-shaped portions are arranged in a non-aligned manner along a straight line in the longitudinal direction. The heater device according to 1. The heater device according to any one of claims 1 to 3, wherein the spiral convex portion has a rectangular shape when viewed in cross section. The heater device according to any one of claims 1 to 4 , wherein the core rod is inserted into the space inside the ceramic body. The heater device according to claim 5 , wherein the cross-sectional area of the space surrounded by the inner wall of the ceramic body and the core rod is smaller on the front end side than on the rear end side of the ceramic body. The portion of the core rod corresponding to the rear end side of the ceramic body has an annular convex portion whose height gradually increases from the rear end side to the tip side of the ceramic body. The heater device according to claim 5 or 6. The heater device according to any one of claims 5 to 7 , wherein the spiral convex portion and the core rod are in contact with each other.

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