JPH0235198Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a positive temperature coefficient thermistor heating element for hot air using a positive temperature coefficient thermistor.

A positive temperature coefficient thermistor has the property that its resistance increases rapidly at a certain temperature, so it has a self-temperature control function and has the property that the heat generation temperature is almost constant. In addition, when this is used as a heating element for hot air, it has the characteristics that there is little change in air temperature and does not overheat even when the air blowing is stopped, and it is well known that using this can provide a very useful heating element. It is being

When a positive temperature coefficient thermistor is used as a heating element for hot air, in order to increase the amount of heat generated by the positive temperature coefficient thermistor, a metal heat sink with a large surface area may be closely fixed to the positive temperature coefficient thermistor. Furthermore, using aluminum as the material for the metal heat sink has good thermal conductivity and
It is also known to be very effective in terms of weight and cost.

Conventionally, methods for making this metal heat sink include extrusion and die casting, but
In either case, it was impossible to reduce the thickness of each part of the heat sink below a certain limit. Therefore, if an attempt was made to increase the amount of heat generated by increasing the surface area of the metal heat radiator, the overall shape would become larger and the weight would become heavier. Therefore, as yet another method, a metal heat radiator has been used in which a thin aluminum plate is bent and sandwiched between two thin plates and then fixed together by brazing. According to this method, the thickness of the metal heat sink can be made as thin as that of an aluminum thin plate, and even if the surface area is increased and the amount of heat generated is increased, a compact and light heat generating body can be provided. Furthermore, it is well known that it is effective in terms of cost, assembly man-hours, etc. for the metal heat radiator to also serve as the electrode because the structure is simplified.

These situations will be explained with reference to the drawings. FIG. 1 shows an aluminum fin 1 made by extrusion. In this case, the thickness of the fin 1 is A
However, it was not possible to make small and lightweight fins with a large surface area because the thickness of the fins could only be reduced to about 1 mm at most. Furthermore, if the surface that is fixed to the PTC thermistor is thick, it cannot sufficiently follow the warpage of the PTC thermistor, so that sufficient thermal bonding cannot be achieved, and the effect of the fin cannot be fully demonstrated.

Figure 2 shows aluminum fins 2 bent into a wave shape.
This is a positive temperature coefficient thermistor heating element using a metal heat sink 4 which is sandwiched between two thin aluminum plates 3 and 3 and fixed by brazing. Reference numeral 5 denotes a positive temperature coefficient thermistor, and electrodes (not shown) made of aluminum spraying or the like are provided on both main planes. Since this electrode and the metal heat sink 4 are in electrical contact and the metal heat sink 4 also serves as an electrode, the structure can be simplified. Methods for electrically contacting and fixing the metal heat sink and the electrodes of a positive temperature coefficient thermistor include fixing with a conductive adhesive, pressing with a spring, and using an insulating adhesive while pressing and curing. There is a very easy way to do this. In FIG. 2, 6 is a terminal board.

By fixing the metal heat sink formed by bending a thin aluminum plate in contact with the electrodes of a positive temperature coefficient thermistor, it is possible to create a positive temperature coefficient for hot air that is lightweight, small, and generates a large amount of heat. A thermistor heating element can be obtained with a simple structure.

However, this heating element had the following drawbacks. When attempting to take out a terminal from a metal heat radiator, it was difficult to fix the terminal portion because all parts of the metal heat radiator were thin and had low strength and were easily bent. Further, when attempting to fix the terminal plate to the metal heat sink by welding or the like, sufficient welding could not be performed because the terminal plate was a thin aluminum plate, resulting in weak strength.

The present invention was made in an attempt to overcome the above-mentioned drawbacks, and aims to provide a positive temperature coefficient thermistor heating element for hot air that is lightweight, compact, generates a large amount of heat, and has a simple terminal connection structure. This is the purpose.

The configuration of the positive temperature coefficient thermistor heating element of the present invention is that an aluminum block is simultaneously attached to a part of a lightweight, small metal heat sink made of a thin aluminum plate by brazing. The number of man-hours required for attachment can be omitted, and the strength of the terminal mounting portion can be increased without increasing the number of assembly man-hours. Therefore, the connection means can be freely selected depending on the material of the terminal board. The most common method is screw fastening,
It can be easily fixed to blocks and is available in a variety of materials. In addition, if the connection means is press-fit,
If a hard material such as stainless steel is selected for the terminal plate, a terminal structure with fewer parts and fewer assembly steps can be obtained. Furthermore, as a reliable means of connection, there is a means of fixing the stainless steel terminal plate and the aluminum block by welding.

In addition, electrical connections with the outside world are generally made with copper wire, so materials that do not have problems with copper connections are used.
Must be used on terminal boards. At that time, if aluminum and a terminal plate made of different metals are connected, the aluminum will easily corrode due to galvanic corrosion if used in a place with high humidity or where water droplets may adhere. In order to prevent this, it would be possible to coat the connection part with resin to make it watertight, but in the structure of the present invention, a depression is formed in the part consisting of the aluminum block and the metal heat sink. By injecting the resin into the structure, it does not peel off like coatings, etc., and the resin can be held sufficiently in the recess and does not flow out, making it possible to connect moisture-proof terminals reliably and easily. A structure will be obtained.

Hereinafter, the configuration of the positive temperature coefficient thermistor heating element for warm air according to the present invention will be described using examples.

FIG. 3 shows an embodiment of the PTC thermistor heating element of the present invention, and FIG. 4 shows an aluminum block used therein. In the figure, 7
is a thin plate positive temperature coefficient thermistor (two in the example)
An aluminum sprayed electrode (not shown) is provided on the surface in contact with the metal heat sink 8. The metal heat sink 8 is made by bending a thin aluminum brazing sheet and sandwiching it between two aluminum plates for bracing. At the same time, an aluminum block 1 is attached to the end of the metal heat sink 8.
0 is also fixed by bracing. This metal heat sink 8 is connected to the positive temperature coefficient thermistor 7, respectively.
These two metal heat sinks 8 also serve as electrodes. Reference numeral 9 denotes a terminal plate made of stainless steel or the like, which is made in consideration of weldability and corrosion resistance. This terminal plate 9 is fixed to the aluminum block 10 by welding.

FIG. 5 shows another embodiment of the present invention, in which a tap is provided in advance on an aluminum block 10a, and a stainless steel terminal plate 9a is fixed to the aluminum block 10a with screws 11.

FIG. 6 shows still another embodiment of the present invention, and FIG. 7 shows an aluminum block and a terminal plate used therein. In this structure, a hole 12 is provided in advance in an aluminum block 10b, and a terminal plate 9 is provided with a protrusion 13 that matches the inner size of the hole 12.
b is press-fitted, and the terminal plate 9b and the aluminum block 10b are fixed.

FIG. 8 also shows yet another embodiment of the present invention, and FIG. 9 is a sectional view taken along line A-A' in FIG. In this embodiment, the extension part 8a of the metal heat sink 8 is
An aluminum block 10c is fixed by brazing so as to be surrounded by the aluminum block 10c.
Then, the stainless steel terminal plate 9c and the aluminum block 10c are fixed with screws in the recessed part formed by the extension part 8a and the aluminum block 10c, and a moisture-proof material such as epoxy resin is applied from above the recessed part. The material 14 is poured and cured to make the connection watertight.

As described above, according to the present invention, since the aluminum block is simultaneously fixed to a part of the lightweight and small metal heat sink made of a thin aluminum plate by brazing, the number of assembly steps does not increase. However, by providing a heat dissipation fin that is in close contact with the PTC thermistor, which increases the strength of the terminal attachment part, the effect of the fin can be fully exhibited and the amount of heat generated can be increased. In addition, a recess can be formed by the fins and the aluminum block, and a terminal structure with high moisture resistance can be provided.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of an aluminum fin constituting a conventional PTC thermistor heating element, Fig. 2 is a perspective view of a PTC thermistor heating element in the conventional example, and Fig. 3 is a perspective view of a PTC thermistor heating element according to the present invention. FIG. 4 is a perspective view of an aluminum block constituting the heating element, FIGS.
The figures are perspective views showing other embodiments of the heating element of the present invention, Fig. 7 is a perspective view showing the aluminum block and terminal plate constituting the heating element of Fig. 6, and Fig. 8 is a perspective view of another embodiment of the heating element of the invention. A perspective view showing another embodiment,
FIG. 9 is a sectional view taken along line A-A' in FIG. 8. 7...Positive characteristic thermistor, 8...Metal heat sink,
8a... Extension portion, 9, 9a, 9b, 9c... Terminal board, 10, 10a, 10b, 10c... Aluminum block, 11... Screw, 14... Moisture proof material.

Claims (1)

[Claims for Utility Model Registration] (1) The above-mentioned metal heat radiating body in which a heat radiating fin made of a thin aluminum plate bent into a corrugated shape and an aluminum block are sandwiched between two other thin aluminum plates and fixed by brazing. A positive temperature coefficient thermistor heating element in which the surface of a thin aluminum plate is closely fixed to both main planes on which electrodes of a positive temperature coefficient thermistor are provided, and a terminal plate made of a metal other than aluminum is connected to the aluminum block. (2) A positive temperature coefficient thermistor heating element according to claim 1, wherein a terminal plate is connected to an aluminum block by welding. (3) The positive temperature coefficient thermistor heating element according to claim 1, wherein the terminal plate is connected to the aluminum block by screws. (4) The positive temperature coefficient thermistor heating element according to claim 1, wherein the terminal plate is connected to the aluminum block by press-fitting. (5) Surround the aluminum block with a metal heat sink,
A positive temperature coefficient thermistor heating element according to claim 1, wherein a terminal plate is connected to the block in a recess formed by the block and a metal heat radiator, and a moisture proof material is injected and hardened into the recess. .