DE3119302A1 - AIR HEATING DEVICE - Google Patents

Description

Description of attorney's file 31606

The present invention relates to an air heater, the thermistor or NTC thermistor elements with a positive temperature coefficient used.

Air heaters with constant temperature in accordion structure are conventionally known in which several Constant temperature heating elements that have a flat shape and are made of thermistor material with a positive temperature coefficient are made, are arranged parallel to each other within a frame, and electrodes attached to the end faces of the respective elements are connected to each other and to a power source by a connecting wire are. Other honeycomb constant temperature air heaters are also conventionally known at which electrodes and connecting wires are arranged on both surfaces of a constant temperature heating element, which has several small holes and by extruding a thermistor material with a positive temperature coefficient is formed into a cylindrical shape. Among these, the air heater in harmonica construction is more difficult and difficult more expensive to manufacture compared to honeycomb because many elements are enclosed and many steps are required for assembly. However, the honeycomb air heater suffers from that

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the pressure drop is large and a blockage often occurs.

The main object of the present invention is to provide an air heater which uses positive temperature coefficient thermistor elements, and is effective and simple in construction is.

The present invention provides an accordion-type air heater which includes flat-shaped thermistor heating elements with positive temperature coefficient, each of which has its respective electrodes on both surfaces, as well as radiating assemblies in contact with each of the electrodes. According to the present invention, the heating efficiency is by Use of radiating assemblies improved, and the number of thermistor heating elements with positive temperature coefficients, that must be used can be greatly reduced as compared with conventional devices.

The subject of the invention is based on the attached, schematic Drawings, for example, explained in more detail; in the drawings is:

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1A and 1B are perspective views of conventional ones, respectively

Air heaters,

2A and 2B a perspective and a sectional view, respectively,

which represents an embodiment of an air heating device according to the invention,

3A is a perspective view of an air heater according to a second embodiment of the present invention,

3B is a view of a section through the main part

of Fig. 3A,

3C is a perspective view of a radiating arrangement which forms part of the FIGS. 3A and 3B heating device shown,

4 to 7 are each a perspective view showing a

represents third to sixth exemplary embodiment of the air heating device according to the invention,

Fig. 8 is a front view showing a modification

the radiation arrangement,

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9 to 11 are each a perspective view showing a

represents seventh to ninth embodiment of the air heating device according to the invention, and

Fig. 12 is a perspective view showing a modification

of the embodiment of FIG.

Accordion-type constant temperature air heaters are conventionally known, wherein, as shown in Fig. 1A, a plurality of heating elements 1 for constant temperature, which are flat in shape and made of thermistor material with positive Temperature coefficients are made, are arranged parallel to each other within a frame 2, and electrodes 3, the are formed on the end faces of the respective elements 1, to each other and a power source through a connecting wire 4 are connected. Other honeycomb constant temperature air heaters are also conventionally known, wherein, as shown in Fig. 1B, electrodes 7 and connecting wires 8 are arranged on both surfaces of a constant temperature heating element 6 having a plurality of small holes 5 and by extrusion of a thermistor material with a positive temperature coefficient is formed into a cylindrical shape. Below is the air heater in an accordion arrangement more difficult and expensive to manufacture compared to those in a honeycomb arrangement because of the many elements and elements included

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of the many steps it takes to assemble it. However the honeycomb air heater suffers from the fact that the pressure loss is large and clogging often takes place.

The present invention will be described through its embodiments with reference to the accompanying drawings.

As shown in Fig. 2A and 2B and Figs. 3A, 3B and 3C, the electrodes 1 1 are respectively provided on both surfaces of a plurality Thermistorbzw. Thermistor elements 10 formed with positive temperature coefficient, which are formed by sintering into a flat rectangular shape to form thermistor heating elements 12 with positive temperature coefficient. Conventionally known methods can be used to form the electrodes 11, such as coating with an electrically conductive material such as silver and copper, metal spraying, vapor deposition or vapor deposition of a metal such as aluminum and copper

Copper, or about nickel plating or plating with nickel or the like., etc. In view of the easy mutual connection of the electrodes 11 of the respective elements 10 and the connection of the connecting wires FIG. 11 is the conventional arrangement of the electrodes 11 according to FIG which they are formed on both end faces of the elements, advantageous. However, given the efficiency, it is great advantageously, the electrodes 11 on both surfaces of the elements to train. As for the shape of the electrodes, they are

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in their shape in view of the effortless shaping and processing preferably essentially square or round. However, the shape of the elements may be as intended Purpose to be chosen.

The metal radiating assemblies 13 are in contact with the surfaces of the respective electrodes 11 of the thermistor heating elements 12 formed with a positive temperature coefficient. In In other words, the thermistor heating elements 12 with a positive temperature coefficient are between two radiation arrangements 13 by means of heat-resistant and thermally conductive silicone adhesive layers 14 clamped, and the protruding parts of the electrodes 11 of the Heating elements 12 are electrically conductive by means of lead wires 15 "Adhesive layers 16 connected. When a tension is on the electrodes 11 of the thermistor heating elements 12 with positive Temperature coefficient is applied, and air is supplied in the direction shown by arrow A, the air becomes warmed up by the heating elements 12. This principle to preserve warm air is also used in the following exemplary embodiments.

The radiating arrangement 13 can be a conventional radiating fin made of a material such as aluminum, as well as a Shape, which enables a better radiation effect. Beneficial Heating effects can be obtained with a radiator assembly in block form formed by chill casting like this

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2A and 2B, or with a radiating arrangement in a form in which metal sheets with excellent radiation properties are bent in the form of channels. Even though the electrodes 11 are formed on both surfaces of the heating elements 12 and the radiation arrangements 13 are electrically insulated However, they can be electrically coupled to facilitate connection of a connecting wire. In this Case, as shown in FIGS. 2A and 2B as well as in FIGS. 3A, 3B and 3C, a plurality of heating elements 12 can be on top of one another be aligned, and the conventional metal radiating arrangements 13 may be placed between each pair of adjacent heating elements 12 in contact with electrodes 11 be who are trained on it. With such a structure, an equivalent heating power can be achieved with about 1/3 to 1/4 of the elements from a conventional accordion-style air heater can be achieved, the heating elements are arranged parallel to each other.

In order to achieve better heating effects and reduce the costs on one To reduce the minimum dimension, a channel-type radiating arrangement can be used, with metal sheets of about 0.3 mm Thicknesses are bent into a wave pattern as shown in Figures 3A, 3B and 3C instead of a radiating arrangement Metal blocks. In this case, since the elastic radiating structures can be combined so that they are attached to the

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Heating elements 12 are attached or glued, the electrical Connection can be easily achieved, and the assemblies serve as both connecting wires and radiating assemblies 13. Furthermore, the radiation arrangements 13 can be in a frame 17 can be incorporated using their elasticity, and the structure can be simplified.

When building these radiation arrangements 13 is when the electrodes 11 on both surfaces of the elements 12 through Metal spraying ■ are formed from aluminum and the radiation arrangements 13 are formed from aluminum sheets, the overall arrangement "resistant to moisture and provides a longer service life as a result of using a combination of the same type of metal.

In order to achieve better heating effects, the division of the radiation arrangements 18 can be reduced or their height increased in order to thereby reduce the surface area of the radiation arrangements 18 to increase (see Fig. 4). In the case of radiation arrangements 18 which are obtained by bending sheet metal, however, leads a smaller pitch results in a smaller height h, and a larger height h results in a larger pitch. Reference is now made to FIG taken, where the reference numeral 19 has a thermistor element positive temperature coefficient, and the reference number 20 designated electrodes.

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3113302

An arrangement as shown in FIG. 5 is thus conceivable. Reference is now made to Figure 5; the reference numeral 21 denotes a thermistor element with a positive temperature coefficient, 22 denotes electrodes and 23 to 26 radiator plates which are bent into a wave pattern with a small pitch and stacked in a number of stages to form radiating assemblies to deliver. With such an arrangement it is possible to increase the total height h of the radiation arrangement,

to increase the surface area of the radiation arrangement, and to facilitate the heating effects. However, this arrangement is disadvantageous in that the number of radiating plates and other parts increases, so that the number of assembling steps also increases and the manufacturing cost becomes high.

To solve this problem, an arrangement can be used, as shown in FIG.

Reference is now made to Figure 6; the reference numeral 27 denotes a thermistor element with a positive temperature coefficient made of thin sheet metal, on the two larger surfaces of which electrodes 28 are formed by flame spraying. The reference numerals 29 and 30 are radiator sheets that are formed by bending a single sheet of aluminum into a wave pattern in a stack of three. These radiation plates 29 and 30 are fixed to both main surfaces of the thermistor element 27 with a positive temperature coefficient attached or glued. Bsi of such a trained graduate

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radiation arrangement can have a one-piece radiation arrangement a greater height h ^ from a multiple stacked, bent sheet metal be formed while having a small pitch of the radiating elements 29 and 30, thereby achieving an air heater having superior heating effects at a lower cost.

Fig. 7 shows another embodiment of the present invention. According to this embodiment, each of the radiation Sheets 31 and 32 made from a single sheet of aluminum, which is bent in a wave pattern. Although this execution Example is similar to the previous embodiment in that the radiating plates 31 and 32 have a small bending pitch and are stacked in a number of tiers, a layer of the same sheet of aluminum between each pair is more adjacent Floors inserted.

With such a radiation arrangement, the sheet metal material is which forms the radiation plates 31 and 32, between the thermistor element 27 with a positive temperature coefficient and the Radiation plates 31 and 32 inserted, making the area more thermal Coupling increased. This leads to better heat transfer from the thermistor element 27 with a positive temperature coefficient to the Radiation plates 31 and 32, which enables better heating effects. Thus, the surface area of the radiation plates 31 and 32 becomes

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supplemented by the area of the metal sheets between the floors, so that more heat can be transferred to the air. To the To increase the output of the heating device even further, the surface area of the radiation arrangements 18 in FIG. 4 can be increased as far as possible. If, however, the height h of the radiation arrangements 18 is increased, the heater also becomes larger in size. It can therefore be conceivable to reduce the width a of the protruding part to create a radiating arrangement with as tight a rib pattern as possible. However, the smaller width a cannot be used during the Machining the thin aluminum sheet can be achieved beyond a certain extent.

Thus, another arrangement can be considered as shown in Fig. 8, where the waveform radiating arrangement is compressed in the transverse direction. In this case in which the width c is the same as the width a 4, the surface area of the radiation arrangement within the total width 1 is twice that of the one shown in FIG. 4 shown in the example. The heating power also increases when such a radiation arrangement in cooperation with the NTC thermistor elements with positive temperature coefficients are used will. In the case of a radiating arrangement of the form shown in FIG. 8, however, those parts which are defined by the Letters A are tight, which leads to clogging with waste threads, dust, etc. This inhibits in a disadvantageous manner the air flow and thus causes a decrease in the output

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power or an abnormal rise in the temperature of the air.

An arrangement as shown in Fig. 9 is proposed in view of these problems. Reference is now made to Figure 9; reference numeral 33 denotes a thermistor element with a positive temperature coefficient, 34 denotes electrodes, the are formed by metal spraying of aluminum, and 35 and 36 denote radiation assemblies which by treatment thin aluminum sheets are formed, with cross-sections in the form of a continuously repeated S-shape. These radiation arrangements

35 and 36 are on the thermistor element 33 with a positive temperature coefficient attached or glued and also function as power supply connections.

In the case of radiation arrangements with S-shaped cross-sections, the Parts B of the radiating assemblies 35 and 36 take the shape of an R-shape. Therefore, the processing of the thin aluminum sheets easier even if the width d is smaller than the width a of the case shown in FIG 35 and 36 with larger surface areas among smaller ones Cost achieved. When the air heater as shown in Fig. 9 using the radiating assemblies 35 and

36 is constructed, then becomes a heater with a large output achieved. Furthermore, since S-shaped cross-sections are used, the parts D of the radiation assemblies 35 and 35

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36 less tight spaces resulting in a heater which is less prone to clogging by dust.

When the air heater of the present invention is incorporated into the Practice is implemented, 'then occurs however in the event that a Metal piece or the like. Is longer than the thickness b of the thermistor element 19 in Fig. 4 with a positive temperature coefficient, at the same time both radiation assemblies 18 touches a short circuit, with a dangerously large electrical current flow. To prevent this, it is possible to increase the thickness b to thereby increase the distance between the opposing electrodes. Such an arrangement, however, leads to a considerable resistance to the air flow and thus disrupts the air flow. This also results in a heavier thermistor element with a positive temperature coefficient and a higher cost.

Thus, an arrangement as shown in Fig. 10 is proposed is.

Reference is now made to Figure 10; the reference numeral 37 denotes NTC thermistor elements with a positive temperature coefficient, with electrodes (not shown) on the two larger surfaces. are formed by metal injection molding of aluminum. That

Reference numeral 38 denotes radiation arrangements which are formed by bending thin aluminum sheets which are attached to the Thermistor elements 37 attached with a positive temperature coefficient or are glued on in order to alternate with these and also to be effective as the power supply connections. The reference

character 39 denotes a heat-resistant insulating paint of the Silicone type, which on the thermistor elements 37 with a positive Temperature coefficients and on the radiation assemblies 38 in the direction perpendicular to the direction of air flow shown by arrow A.

With such an arrangement, contact of a conductor such as a piece of metal with the heater will not cause any Short circuit. Furthermore, the thickness of the thermistor elements 37 must also positive temperature coefficient are not increased, so that an air heater with low resistance to flowing Air is reached, which can be produced cheaply. Although it is advantageous that the insulating paint 39 is applied to the thermistor elements 37 with positive temperature coefficient and the radiation arrangements 38 in the direction perpendicular to the air flow direction is painted, it can also be painted over the entire heater, depending on the type of color and the Way of application.

In order to put the present invention into practice, an arrangement as shown in Fig. 11 can be used to facilitate the Isolation and assembly of the device are used. Reference is now made to Figure 11; the reference numeral 40 denotes a thermistor element with a positive temperature coefficient in the form

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of a thin sheet, with larger surfaces of it on both Electrodes 41 are formed which are formed by metal injection molding of aluminum. Radiation arrangements 42 and 4 3 made of aluminum are glued on with epoxy glue (not shown). Reference numerals 44 and 45 denote power supply lead wires, which on the surface electrodes 41 of the thermistor element 40 with a positive temperature coefficient with an electrical conductive adhesive such as solder are attached or glued. The reference numeral 46 denotes a sheet-shaped insulator from Silicone rubber or the like. Which encloses the entire device in such a direction that it does not get into the air flow therethrough intervenes. The reference numeral 47 denotes eyelets made of brass or the like, which fasten the sheet-shaped insulator 46.

According to this arrangement, since the radiation arrangements 42 and 4 3 are fixed with an adhesive, the outside of the air heater may be insulated with a simple structure and need not be require complicated steps to attach the device. Furthermore, since the sheet-shaped insulator 46 is the exterior of the device includes, the number of parts required to construct the device is reduced, assembly is simplified and the device can be less expensive.

FIG. 12 shows a modification of the arrangement shown in FIG. 11, the sheet-like insulator being a heat-shrunk tube 48 includes. If such hose or tube 48 encloses the device and is heat shrunk, then

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can be the step of wrapping with the web-shaped Isolator can be eliminated, providing an air heater that is less expensive and easier to assemble.

To show the beneficial effects with the present Invention are achievable, the description continues with reference to data obtained through experiments which were carried out in accordance with the exemplary embodiments shown in the accompanying drawings.

First, as shown in Fig. 2, the electrodes 11 were formed by a silver paint or metal spraying of aluminum on both surfaces of the sheet-shaped thermistor element 10 with positive temperature coefficient (switching temperature 220 ⁰ C, initial resistance 20 Sl ·), with dimensions of 30 χ 20 χ 1.5 mm to form the thermistor heating elements 12 with a positive temperature coefficient. Using two commercially available radiation assemblies 13 with 100 mm length, 25 mm width and 40 mm length of the projecting parts together with the thermistor heating elements 12 with positive temperature coefficient, which have been described above, the heating elements 12 between them by heat-resistant and thermally conductive silicone -Adhesive layers 14 held. The protruding parts of the electrodes 11 of the heating elements 12 are mutually connected to the conductive adhesive layers 16 by the lead wires 15. By the same method, the electrodes 11 are mutually connected on both the front and rear surfaces of the elements

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Terminal connecting wires connected.

When an air heater using five such heating elements "" was used as the air heater, a heating output corresponding to 36Ω was obtained. The same air heating effects were obtained as with a conventional device (as shown in Fig. 1A) using 18 to 20 heating elements of the same dimensions.

If a heat-resistant and electrically conductive adhesive for the heat-resistant silicone adhesive layers 14 in the Embodiment is used, which are shown in Fig. 2A and 2B, then must because the radiation arrangements 13 also for electrical connection of the electrodes 11 of the heating elements 12 are used, the lead wires 15 are not attached together with the electrically conductive adhesive layers 16, so that the connecting wires can be connected directly to the radiation arrangements 13. Because of this, the width of the heating element 12 be the same as that of the radiation assembly 13, resulting in a better heating effect and simpler manufacture.

In the embodiment shown in Figs. 3A, 3B and 3C, the heating elements 12 are the same as those in Fig. 2. Next an aluminum strip 20 mm wide and 0.3 mm thick is bent in such a way that it has several ribs 5 mm high in order to To form radiating assemblies 13 as shown in Figures 3A, 3B and 3C. The length of the radiation arrangement is designed so that it is equal to the length of the heating element 12 (30 mm). The heating elements 12 and the radiation arrangements 13 are

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inserted into the frame 17 together with a heat-resistant insulator and fixed there, which has internal dimensions of 30 × 56 mm and 20 mm in height. The number of combined heating elements and radiation arrangements corresponds to the relationship between the radiation effects and the properties of the elements 12 certainly. However, the same output power as that achievable with the device shown in FIG. 2 becomes with four heating elements 12 achieved when a heating element 12 with two Radiation arrangements 13 is connected.

The radiating arrangements 13 can be superimposed as this is shown in Fig. 3A, 3B and 3C, or according to an andt ren method, depending on the elastic effects and the properties of electrical and thermal conductivity of the material the arrangement.

In summary, according to the present invention, the heating effect can be achieved through the incorporation of the radiation arrangements described above be improved. The number of thermistor elements with a positive temperature coefficient can be reduced, and the radiation effects can be improved as compared with conventional devices. The radiation arrangement can also be effective as lead wires for electrodes, resulting in simpler structure, easier assembly, and lower manufacturing cost leads.

- End of description -

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Claims (1)

DR. BERG DIPL.-ING. STAPF DIPL.-ING. SCHWABE DR. DR ^.: SAifr> MAtR PATENT LAWYERS P.O. Box 860245 8000 Munich 86 Attorney File 31606 May 14, 1981 MATSUSHITA ELECTRIC INDUSTRIAL CO., LTD. Osaka, Japan Air heater EXPECTATIONS M A air heating device, characterized in that thermistor heating elements (10; 19; 21; 27; 33; 37; 40) with a positive temperature coefficient and flat shape are provided, the thermistor elements with a positive temperature coefficient each having electrodes (11; 20; 22; 28; 34; 41) and that heat radiating arrangements (13; 18; 23, 24, 25, 26; 29, 30; 31, 32; 35, 36; 38; 42, 43) made of metal in Contact with the 130067/0827 r <0 «9) 988272 Telejrunme: IJUUW '/> ->« *.' Buik accounts: Hypo-Buik Munich 4410122850 988273 VT / R / να BEROSTAPFPATENT MUnchen (BLZ 70020011) Swift Code: HYPO DE MM 3113302 Surfaces of the respective electrodes are arranged. 2. Air heating device according to claim 1, characterized in that that both electrodes of the thermistor heating elements with a positive temperature coefficient and the radiation arrangements made of metal are directly electrically connected to one another. 3. Air heating device according to one of claims 1 or 2, characterized characterized in that the radiation arrangements are made by bending highly radiation-capable metal plates into several Waves or ribs are formed. 4. Air heating device according to claim 1, characterized in that that the radiation arrangements comprise elastic metal plates with continuously corrugated or ribbed cross-sections, which clamp between each other the thermistor heating elements with positive temperature coefficients. 5. Air heating device according to claim 2, characterized in that the electrodes of the thermistor heating elements with positive Temperature coefficient and the radiation arrangements are formed from the same metal. 130067/0827 6. Air heating device according to claim 5, characterized in that that the electrodes of the thermistor heating elements with a positive temperature coefficient and the radiation arrangements Made of aluminum. 7. The air heater of claim 3, wherein the metal radiating assemblies adhere firmly to the electrodes of the thermistor heating elements with a positive temperature coefficient, characterized in that the Metal1 radiation arrangements formed by bending a single sheet of metal into a corrugated shape and in a number of stages are stacked. 8. Air heating device according to claim 7, characterized in that that parts of the metal sheets which form the radiating arrangements, each between stages of the metal radiating arrangements are arranged. 9. Air heater according to claim 1 or 2, wherein the metal radiating assemblies firmly on the electrodes of the thermistor. Adhere heating elements with a positive temperature coefficient, characterized in that the metal radiating arrangements comprise thin aluminum sheets and cross-sections with a continuously repeated S-shape. 13006 7/0827 0O. The air heater of claim 2, wherein the metal radiating assemblies adhere firmly to the electrodes of the thermistor heating elements with a positive temperature coefficient, characterized in that an electrically insulating paint is applied to the surfaces of the thermistor heating elements with positive Temperature coefficients as well as the metal radiation arrangements is applied, wherein the surfaces are present at least in the direction perpendicular to the air flow. 11. The air heater of claim 2, wherein the metal radiating assemblies adhere firmly to the electrodes of the thermistor heating elements with a positive temperature coefficient, characterized in that a sheet-like insulator the Entire device encloses in such a direction that it does not interfere with the air flow. 1300 6 7/0827