JPS6244392B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a heater for heating a fluid whose heating element is a positive characteristic porcelain suitable for heating a fluid, particularly a liquid or a mixture of a liquid and a gas.

BACKGROUND ART Conventionally, as a fluid heating heater using positive characteristic porcelain as a heating element, for example, a heater made of positive characteristic porcelain in a honeycomb shape is known. However, positive characteristic porcelain is susceptible to thermal shock, and the electrodes installed in honeycomb-like positive characteristic porcelain may corrode when in contact with fluids, especially water or flammable liquids, so it cannot be used stably for a long period of time. It was hot.

For this reason, heaters with an insulating coating applied to the surface of a honeycomb-shaped positive temperature porcelain heating element are also known, but the coating material swells and peels off, making it impractical when the fluid is liquid. It was hot.

There is also a known heater in which a plate-shaped positive temperature coefficient porcelain heating element is closely attached to the outer periphery of a metal body having a fluid flow path. In order to convey only
It is necessary to make the heater flat, to make the fluid flow path a narrow hole, and the resistance to fluid flow increases, and there are significant restrictions on the shape of the heater.

The present invention is a fluid heating heater which eliminates these drawbacks of conventional heaters using positive characteristic porcelain as a heating element, and which has a fluid flow passage inside, and has a fluid flow passage from the outermost side of the fluid flow passage. A fluid comprising a metal member having a protrusion or crosspiece that crosses the fluid and has a cavity therein, and a positive characteristic porcelain heating element provided in the cavity in a liquid-tight or air-tight manner with respect to the fluid; This fluid heating heater is particularly suitable for heating a liquid or a mixed fluid of a liquid and a gas.

The details of the present invention will be explained below with reference to the drawings.
FIG. 1 shows a specific example of a fluid heating heater according to the present invention, in which a crosspiece 24 is provided in the fluid flow path 21 of a metal member 22 having a fluid flow path 21, and a hollow space is formed in the crosspiece 24. 25, and a plate-shaped positive temperature characteristic ceramic heating element 26, for example, is mounted in this space.

The positive characteristic porcelain heating element 26 is provided with electrodes on both its wide surfaces, and the two positive characteristic porcelain heating elements 26 are connected to a vacant space by a spring 38 which also serves as one lead electrode of the two positive characteristic porcelain heating elements 26. is pressed against the inner wall surface of the When the metal member 22 is used as one electrode and a voltage is applied between the spring 38 which also serves as an electrode and the metal member 22, the positive characteristic porcelain heating element 26 generates heat, and the heat is transferred to the crosspiece 2.
It will be transmitted to 1. The crosspiece 21 and the metal member 22 are made integrally, and a heat dissipation grid is provided integrally with the metal member between the crosspiece 21 and the metal member 22 or between the crosspieces, so that positive characteristic porcelain heat generation is achieved. The heat of the body 26 is quickly transferred to these metals and heats the fluid flowing through the fluid flow passageway 21.

FIG. 2 shows another specific example of the present invention, in which a fluid flow passage 21 provided in a metal member 22 is shown.
A projection 23 is provided therein, a cavity 25 is provided within the projection 23, and a positive temperature porcelain heating element 26 is provided in each cavity 25. Positive characteristic porcelain heating element 2
Electrodes are provided on both wide surfaces of the positive characteristic porcelain heating elements 26, and the two positive characteristic porcelain heating elements 26 are connected to the empty space 25 by a spring 38 which also serves as one lead electrode of the two positive characteristic porcelain heating elements 26.
is pressed against the inner wall surface of the Positive characteristic porcelain heating element 2
6 is pressed against the inner wall surface of the cavity 25 by the spring, the heat is quickly transferred from the inner wall surface of the cavity 25 to the protrusion 23.

In order to make it easier to transfer the heat of the positive characteristic porcelain heating element 26 to the inner wall surface of the cavity 25, it is not recommended to apply heat transfer grease or the like between the inner wall surface of the cavity 25 and the electrode surface of the positive characteristic porcelain heating element 26. It is valid.

The metal member 22 is preferably made of a metal material with good thermal conductivity, low specific heat, and good workability, such as aluminum, aluminum alloy, zinc,
Zinc alloys, magnesium, magnesium alloys, copper or copper alloys are practical.

FIGS. 3 to 7 show a space 2 provided in a metal member 22.
5 shows another structure in which a positive characteristic porcelain heating element 26 is heat-conductively mounted in the porcelain heating element 5. FIG. 3 shows the case where one positive characteristic porcelain heating element 26 is provided, and the empty space 2
5 includes a positive characteristic porcelain heating element 26 and a lead electrode plate 2.
7. Insulating plates 28 are sequentially laminated. Electrodes are provided on both wide sides of the positive characteristic porcelain heating element 26, and one side of the positive characteristic porcelain heating element 26 is provided with the space 2.
5 in close contact with the inner wall surface, and the other surface is a lead electrode plate 27
The lead electrode plate 27 is insulated from the inner wall surface of the cavity 25 by an insulating plate 28.

If the positive characteristic porcelain heating element 26 and the lead electrode plate 27 are shifted, the lead electrode plate 27 and the positive characteristic porcelain heating element 26 may be misaligned.
It is useful to provide an insulating spacer 29 to prevent the side surface of the spacer 25 from coming into contact with the inner wall surface of the cavity 25 and causing a short circuit. In order to bring the positive characteristic ceramic heating element 26 into close contact with the inner wall surface of the cavity 25, a conductive filler may be inserted between the inner wall surface of the cavity 25 and the electrode surface of the positive characteristic ceramic heating element 26, or a conductive filler may be inserted between the insulating plate 28 and the lead. A conductive paint can be applied between the electrode plates 27 and between the insulating plate 28 and the inner wall surface of the space 25.

In FIG. 4, two positive characteristic porcelain heating elements 26 are used.
The structure is such that one surface of each of the positive characteristic ceramic heating elements 26 is brought into close contact with the inner wall surface of the hole 25, and a lead electrode plate 27 is inserted between the two positive characteristic ceramic heating elements 26. In this structure, the electrical insulating plate 28 is not required and a compact design is possible.

FIG. 5 shows a structure in which the metal member 22 is completely insulated.
8, lead electrode plate 27, positive characteristic ceramic heating element 26,
It has a structure in which a lead electrode plate 27 and an insulating plate 28 are sequentially laminated and inserted.

FIG. 6 shows a heater having a structure in which a metal member 22 is completely insulated and two positive characteristic porcelain heating elements 26 are combined.
8, lead electrode plate 27, positive characteristic ceramic heating element 26,
It has a structure in which a lead electrode plate 27, a positive characteristic ceramic heating element 26, a lead electrode plate 27, and an insulating plate 28 are sequentially laminated and inserted.

In Figure 7, the lead electrode plate is a positive characteristic porcelain heating element 26.
This figure shows a structure using a spring lead electrode plate 38 having a spring action that presses one surface of the electrode plate 38 toward the wall surface of the cavity 25. When the positive characteristic porcelain heating element 26 is energized and the positive characteristic porcelain heating element 26 generates heat, the temperature of the spring portion varies depending on the temperature at which the resistance of the positive characteristic porcelain heating element 26 increases, but is between 100°C and 300°C. Therefore, it is preferable to use a spring material having a certain heat resistance, such as beryllium copper, phosphor bronze, stainless steel, or titanium copper.

Further, it is preferable that the pressing force of the spring is approximately 2 kg or more.

Further, the electrical insulating plate 28 shown in FIGS. 3, 5, and 6 needs to have good thermal conductivity, and is made of alumina porcelain, beryllia porcelain, or the like.

In addition, the thickness of the outer wall of the fluid flow path of the metal member 22, the number and size of the crosspieces 24 and protrusions 23 provided on the metal member 22, etc. may be arbitrarily set as necessary, but before flowing the fluid, When the metal member 22 is preheated and the stored heat is used, the metal member 22 is made thicker as a whole, and the heat generation amount of the positive characteristic porcelain heating element 26 is adjusted according to the flow rate of the fluid without requiring preheating. In the case of a heater that changes sensitively, the part of the metal member 22 that is in contact with the wide electrode surface of the PTC porcelain heating element 26, that is, the wall surface of the space between the crosspiece 24 and the protrusion 23, is thin, for example, 0.5 to 1.0 mm. It is effective to set it to a certain degree.

FIG. 8 shows a structure in which an insulating spacer is omitted, in which a recess 30 is provided in the hole axis direction on one surface of the PTC porcelain heating element 26, and a bottom surface 3 of the recess 30 is provided.
1 or electrodes are provided on the bottom surface 31 of the recess and the side surfaces 32 of the recess. If the springy lead electrode plate 38 is inserted into this recess, the springy lead electrode plate 38 will not protrude from the recess, thereby preventing a short circuit between the lead electrode plate 27 and the metal member 22.

Positive characteristic porcelain heating element 26 with such a concave cross-sectional shape
The method for manufacturing is to apply electrodes to the entire surface of positive characteristic porcelain, for example, by electroless plating, then polish or cut the surface perpendicular to the hole axis direction to make it an electrode-free surface, and then create a recessed surface. Polish the surface of
Just remove the electrode.

FIG. 9 shows a case where a plurality of positive characteristic porcelain heating elements 26 are used in the axial direction of the cavity 25.
If the void is long in the axial direction, the elongated PTC porcelain heating element is likely to be damaged by handling, and if it is warped or undulated, thermal adhesion with the metal member 22 cannot be expected, and the spring By using a plurality of positive characteristic porcelain heating elements 26 in the axial direction, the susceptibility to damage when pressed by the lead electrode plate 38 can be solved.

As the electrodes of positive characteristic porcelain heating elements, electrodes whose main components are nickel, silver, aluminum, etc., can be used by electroless plating method, paste coating method, metal spraying method, etc. It is preferable that the material be in ohmic contact with the material. The electrode surface of the PTC porcelain heating element on the side that comes into contact with the inner wall surface of the cavity is desirably in close thermal contact with the inner wall surface of the cavity, so it is required to be a smooth surface, so the electrode is electroless. It is preferable to use the plating method or the paste coating and baking method.

In addition, since a large inrush current flows through a positive characteristic porcelain heating element when it is energized, it is necessary that the electrode itself not only have low resistance, but also have low contact resistance with the lead electrode plate and the metal on the inner wall of the cavity. .
For this reason, it is preferable to use silver or an electrode containing silver as a main component, but when using this fluid flow heater with a DC voltage, consideration must be given to the migration of silver. That is, since silver easily moves to the negative side under a DC electric field, the silver electrode surface can only be used on the negative side under a DC electric field. In such cases, in order to improve heat transfer and to prevent migration, the electrodes of the positive characteristic porcelain heating element on the metal member side should be plated or baked with a silver layer on top of the nickel plating, or electrodes made of silver as a main component may be used. It is sufficient to apply the paste and bake the electrode, and then connect this electrode side to the negative side of the power supply.

The metal member having the fluid flow passage can be made by die casting, die casting, machining, or a combination thereof. Furthermore, since the fluid flow path provided in the metal member and the space in which the PTC porcelain heating element is installed must be separated airtightly or liquidtightly, the fluid flow path and the axial direction of the space are provided at right angles. This is desirable.

No. 10 for the purpose of increasing the heat output of the heater.
As shown in the figure, it is effective to thermally attach the positive characteristic porcelain heating element 26 to the outer wall or outer circumferential part 33 of the metal member 22 having the fluid flow passage 21. For example, as shown in FIG. The positive characteristic ceramic heating element 26 can be attached to the portion 33 with an insulating plate via a lead electrode plate 27.

Furthermore, as shown in FIG. 11, a space 25 may also be provided in the outer peripheral wall of the metal member 22, and the PTC porcelain heating element 26 may be mounted for heat transfer in the same structure as that mounted on a crosspiece or protrusion. Of course it's a good thing.

In addition, as shown in FIG. 12, a cross-shaped fin 34 or a wire mesh for heat radiation may be attached to at least one end surface of the metal member 22 in the axial direction of the fluid flow passage 21, or as shown in FIG. protrusion 3
5, or as shown in FIGS. 14 and 15, a metal piece 36 or a wavy heat dissipating fin 37 may be installed in the fluid flow path 21 formed by the crosspiece 24 and the metal member 22 in a thermally conductive manner with the crosspiece 24. mounting or further fluid flow path 2
The amount of heat dissipation can be increased by providing fine irregularities on the wall surface of 1 or by installing a mat-shaped heat transfer member made of metal fibers in the fluid flow path to conduct heat with the metal member.

As described in detail above, the present invention provides a fluid flow path in a metal member, and provides a space inside the metal member for mounting positive characteristic porcelain isolated from the fluid flow path. Since this is a heater for heating fluids, in which the characteristic porcelain heating element is installed in a heat conductive manner with the inner wall surface of the cavity, the positive characteristic porcelain heating element does not come into contact with the fluid, so the positive characteristic porcelain heating element is not corroded by the fluid. ,
It is a highly reliable fluid heating heater, and because the crosspieces and protrusions that are integrally provided with metal members in the fluid flow path are heated from within, the amount of heat that is wasted from the outer periphery of the heater is small. It is a heater with good thermal efficiency and quick response.
If necessary, the preheating effect can be utilized by adding heat capacity to the metal member.Also, since a positive temperature porcelain heating element is installed in the cavity, the heater is compact overall and has a positive temperature characteristic. It is able to fully utilize the non-overheating properties of porcelain heating elements, and heats heavy oil and kerosene in instantaneous water heaters, shower heaters, heavy oil burners, and kerosene burners to reduce their viscosity and create fine mist. The present invention is industrially extremely useful and can be used as a heater suitable for generating water, a heater for heating dental oral cleaning water, a heater for heating and vaporizing automobile gasoline or a mixture of gasoline and air, etc. be.

[Brief explanation of the drawing]

Figures 1 and 2 are basic configuration diagrams of the heater of the present invention, Figures 3 to 11 are specific examples of the configuration of the heater of the present invention, and Figures 12 to 15 are metal members used in the heater of the present invention. This is a specific example. DESCRIPTION OF SYMBOLS 21...Fluid flow path, 22...Metal member, 23...Protrusion, 24...Bar, 25...Protrusion, void space in bar, 26...
Positive characteristic porcelain heating element, 27... Lead electrode plate, 28...
Electrical insulating plate, 29... Electrical insulating spacer, 30... Positive characteristic porcelain recess, 31... Positive characteristic porcelain recess bottom, 32
... side surface of positive characteristic porcelain recess, 33 ... outer periphery of metal member,
34... Heat radiation fin, 35... Heat radiation unevenness, 36...
Heat dissipation metal piece, 37... Corrugated metal piece, 38... Spring lead electrode plate.

Claims (1)

[Scope of Claims] 1. A metal member having a fluid passage inside, a protrusion or crosspiece that crosses the fluid from the outermost part of the fluid flow passage into the fluid flow passage and has a cavity inside; 1. A heater for heating a fluid, characterized in that the cavity is provided with a positive characteristic porcelain heating element that is liquid-tight or air-tight with respect to the fluid. 2. One surface of the positive characteristic porcelain heating element is brought into close contact with the inner wall surface of the void, an electrode plate is brought into close contact with the other surface of the positive characteristic porcelain heating element, and the other surface of the electrode plate is inserted into the void through an insulating plate. The fluid heating heater according to claim 1, which has a structure in which the heater is in close contact with another inner wall surface of the heater. 3 Inside the empty space, there is an electrode plate, a positive characteristic porcelain heating element,
2. The fluid heating heater according to claim 1, wherein the electrode plate and the insulating plate are sequentially laminated. 4. The fluid heating heater according to claim 1, wherein there is a plurality of positive characteristic porcelain heating elements. 5. The fluid according to claim 4, wherein one surface of each of the two positive characteristic porcelain heating elements is brought into close contact with the inner wall surface of the cavity, and an electrode plate is inserted between the positive characteristic porcelain heating elements. Heater for heating.