JPS5843872B2 - Fukugou Hatsunetsoshi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a composite heating element that combines a ceramic heater having a thick film resistor (printed) pattern and a positive temperature coefficient thermistor element as one component, and its purpose is to By relying on a positive temperature coefficient thermistor element that generates rapid heat generation at the initial stage, and on a heater after that, this can be corrected, especially when the outside temperature is low and the heater cannot be expected to generate the necessary amount of heat within the desired time. This is compensated for by the heat generated by the characteristic thermistor element, and in this case, by combining the heater and thermistor element into one component using a bowl-shaped recess,
By aligning the heat generating surfaces of the heater and thermistor element on the same side, the heating capacity of both can be effectively utilized, simplifying incidental equipment and ease of handling6. Alumina ceramics, etc. The disc-shaped main body is made of ceramics such as forsterite ceramics, which have a certain strength as a structural member and have good electrical insulation.
Ceramic heaters with resistance patterns made of Mo-Mn, W, etc. formed on their surfaces using thick film technology are more robust and have a longer lifespan than heaters with nichrome wires installed in grooves, and unlike nichrome wires, they oxidize due to heat generation. Because it is not subject to wear or chemical corrosion due to the environment in which it is used, and has good heating resistance characteristics, it has come to be widely used in various devices containing heating elements. The mechanism used in the auto-choke operation is listed below.

That is, a thin disk-shaped ceramic heater with the above-mentioned resistance pattern provided on the upper surface is mounted on a shaft, one end of the bimetal is fixed to the upper side of the heater, and the rest of the bimetal is connected concentrically around the shaft. Then, the other end (free end) is fixedly connected to the choke valve opening/closing device as appropriate so that the choke valve is closed in the normal state (non-heating state), and when the starting switch of the automobile is turned on, the above-mentioned heater is connected to the battery. In this system, the opposing bimetal is successively heated and expanded to gradually open the choke valve, and once the temperature inside the engine reaches a certain level, the bimetal circuit is automatically turned off using another switch element. .

However, the ceramic heater with such a mechanism still has the following problems.

That is, the thick film resistance pattern of this heater is capable of providing the necessary amount of heat at an early stage to enable the expansion of the bimetal that controls the opening of the choke valve.
For example, as shown in curve A of the one-hour temperature characteristic shown in Figure 7, if the temperature that controls the opening of the choke valve is from point Until then, it will be K 60 Sec.

Considering the auto choke mechanism, when the internal temperature of the engine rises after the engine starts, the choke valve must be gradually opened accordingly. If it does not open, you will be supplying an unnecessarily rich gas mixture to the engine.

The present invention compensates for the lack of heat at the initial stage of energization by applying a positive temperature coefficient thermistor element to a heating element mechanism using such a ceramic heater. They are combined into a single component so that they have a heat dissipation function on the same side, and both generate heat when energized. However, in the early stages of energization, the positive temperature coefficient thermistor element is the main heat source, and when the temperature rises to a predetermined temperature, the thermistor The element generates only a small amount of heat, allowing the ceramic heater to play the main role, and by combining both as a single component with a heat dissipation function to the same side, the heater can be used alone, with positive characteristics. This makes it superior in thermal characteristics to a thermistor element alone.

Embodiments in which the present invention is applied to the above-mentioned auto choke mechanism will be described below. FIGS. 1 to 3 show the most desirable first embodiment, and FIGS. 5 and 6 show the second embodiment. ．． It is a structural diagram showing a third example.

The gist of the element of the present invention that is common to these embodiments is that the ceramic heater 1 has a bowl-shaped cross section and has a thick film resistor pattern 13 of a desired shape, width, and thickness on the upper peripheral edge 11; A positive temperature coefficient thermistor element 2 is fixed in a recessed part 12 of the heater 1 and has a heat generating surface on the same side as the heater 1, and the heater 1 and the thermistor element 2 are electrically connected in parallel. This is a composite heating element characterized by:

Next, the details of the device of the present invention implemented in each example are as follows.

First, in the first embodiment, the ceramic heater 1 has a circular planar shape and a bowl-shaped cross section as shown in FIG.
A meandering thick film resistor pattern 13 is provided on the entire circumference of the resistor 1 in a discontinuous ring shape.

As is well known, this Nonokoon 13 has Mo-Mn, W
It is printed using a thick film method using a resistive paste such as the above, and the meandering shape is intended to increase the effective amount of resistance for the limited area of the upper peripheral edge 11.

As is clear from FIGS. 1 to 3, the starting and ending ends of this pattern 13 extend toward the inner wall of the recessed portion 12 and further extend downward to form lead-out pads 14 and 15.

As the ceramic, alumina ceramic is usually used, but forsterite, which has good strength and insulation properties, may also be used.

The positive characteristic thermistor element 2 in this example has positive and negative electrodes 22 and 21 concentrically fixed on the upper surface of a thin disc-shaped element main body 20 with a gap 23 in between, and is conductive to the main body 20. The thermistor element of this quib is shown as having a conductive portion 26 made of a material fixed to its lower surface, but the thermistor element of this quib is disclosed in Japanese Patent Application No. 49-36353 (Showa 49) filed by the present applicant.
(filed on March 29, 2013), and its characteristic point is that the first energized heat generating area due to initial energization is connected to the gap 23.
After this region spreads to the conductive portion 26, the main body region between the conductive portion 26 and the electrodes 22-21, which is outside this region, is formed in the main body region between the electrodes 22-21 separated by As the energization heat generation area, a steady energization heat generation state is established, whereby the current at the initial stage of energization can be suppressed to a small value and a relatively sufficient amount of heat generation can be obtained.

Of course, the positive temperature coefficient thermistor element in the present invention is not limited to this example, and application of known commercially available products as shown in FIGS. 5 and 6 is not excluded.

The positive electrode 22, the negative electrode 21, and the resistor pattern 13 are connected in parallel to a power source (such as a battery) E as shown in FIG.

In order to specifically implement this, the starting end of the electrode 22 is made to hang down along the side wall of the main body 20 as shown in FIGS. Pads 25 are formed by hanging down along the side edges of the main body 20 from a part thereof, and the lead-out pads 24, the lead-out pads 14 of the pattern 13 mentioned above, and the lead-out pads 25 and 15 are brought into contact with each other, respectively. , the longer one of these, i.e., the lead-out/rod 14.15, is connected to the electrode terminals 4, 5 attached to the bottom surface of the heater 1 through the conductive parts 3, 3 of the through hole 31.31 bored in the heater 1, respectively. Connecting.

It will be seen that the connection state shown in FIG. 4 is thus obtained.

Reference numeral 6 in FIG. 2 is a mounting leg for fixing the element of the present invention to the device.

1st. The elements of the second and third embodiments are both shown as examples of use in the auto-choke mechanism described above, and are therefore provided with a shaft hole in the center of the element. Reference numeral 16 indicates the shaft holes of the heaters, and the state in which the bimetal in the first embodiment is attached to the shaft S is shown by the two-dot chain line in FIG.

That is, one end of the bimetal BM is fixed to a shaft S, and the other end is connected to a valve opening/closing device VA that controls the opening and closing of a choke valve CV. Valve C■ is opened and closed by expansion and contraction.

The difference between the second and third embodiments and the first embodiment is the difference in the thermistor element 2. In the case of the second embodiment, the negative and positive electrodes 21 and 22 of the thermistor element 2 are different from each other. The electrodes 22 and 21, the resistance pattern 13, and the electrode terminals 4 and 5 are provided on the upper surface of the element 2 with a gap 23 therebetween, and the lead-out pads 141 have the same lead-out method as the lead-out pads in the previous example. , 241 and 251, 151.

Third embodiment: The thermistor element here is an example in which positive and negative electrodes 22 and 21 are provided oppositely on both upper and lower surfaces. Pattern 13 and electrode terminal 4
, 5 are connected.

Regarding the difference in function of the thermistor elements in the second and third embodiments, in the second embodiment, only the area between the gap 23 of the main body 20 becomes an effective heat generation area, so excessive initial current can be sufficiently suppressed. However, since this region is only a narrow part of the entire body 20, the amount of heat generated is somewhat insufficient.On the other hand, in the third embodiment, the electrodes 22,21 are Since it covers the entire area, the amount of heat generated is superior to that of the previous example, but on the other hand, the initial current is small and the power consumption of the power source E is large at the initial stage of energization.

Both the second and third thermistor elements are well known, but
As already mentioned, the first embodiment is related to the earlier application, and can be said to be the most desirable embodiment of the present invention.

The heating element of the present invention has the above-mentioned configuration, and the positive temperature coefficient thermistor 2 is placed in the recessed part 12 of the ceramic heater 1, which has an X-bowl shape in cross section and has a series of thick film resistance patterns 13 on the upper peripheral edge 11. are fixed, and the heater 1 and thermistor element 2 are electrically connected in parallel, so when both are energized, they start generating heat from each other, but in the initial stage of energization, Electrical property dimensions\Thermistor element 2 constitutes the main body of heat generation, and the heat generation main body then shifts to the ceramic heater 1.The characteristics of the device of the present invention are explained using the graph in Fig. 7. This is the temperature one-hour characteristic when a heater exactly the same as heater 1 used in the first example is used alone, and the same thermistor element is used for the opening. Carai in comparison.

Up to point X, where the mouths meet, the thermistor element alone shows a rapid temperature rise and a higher amount of heat generation, but after the confluence point X, the heater alone produces a greater amount of heat generation.

These are conventionally known electrical characteristics of heaters and thermistor elements.

However, when the device of the present invention is used (the first embodiment), as shown in Figure a, at the initial stage of energization (at least up to point X), the +- mister element alone It has a steeper temperature gradient than that of a dog, and has a calorific value similar to that of a dog.

As is clear from the comparison with Carvey, it still far exceeds the amount of heat generated over time after point X.

In other words, in the case of the element of the present invention as a heater alone,
In the case of a thermistor element alone, it can exhibit far superior heat generation characteristics in terms of the amount of heat generated at the initial stage of energization and thereafter.

By the way, as mentioned before, in this type of heating element, it is necessary for the mechanism of the device to absorb the amount of heat generated at the initial stage of energization. Since the element heat generation amount is small and the rising slope is steep, the problems of conventional products can be sufficiently covered.

When the heater 1 and the thermistor element 2 are connected in series, the circuit resistance increases and the circuit current unnecessarily decreases. I can't.

As shown in Fig. 7, the force a shows excellent heat generation characteristics not only at the initial stage but also at both shoulders when the thermistor element 2 and heater 1 are connected in parallel to the same power source E. This is because the current supplied from the heater is effectively used to generate heat for the husband.

Thus, it will be understood that the temperature-time characteristics of the device of the present invention are superior to those of known products.

The test conditions in Figure 1 are: power supply E is 12V, resistance of ceramic heater 1 is 11Ω, resistance of thermistor element 2 is 6Ω, and the measurement point is directly above the resistance pattern 13 when either heater 1 or thermistor element 2 is used alone. and electrode 22-21
In the case of a combination of both (the present invention) on Ai, 6
, directly above the midpoint of the electrodes 22-21 of the thermistor element 2.

As described above, according to the present invention, the amount of heat generated at the initial stage of energization is smaller than that of a conventional heater alone, so the lack of heat amount during this period can be sufficiently compensated for, and the thermal expansion of the bimetal can be sufficiently promoted, resulting in a choke. The operation of the valve can be made as accurate as possible, and since the heater 1 and the thermistor element 2 are combined into one component using the recessed part 12, the heat generating surfaces of both components can be aligned on the same side. The element of the present invention is extremely useful as a heat generating element of this type because the heating capabilities of both elements can be effectively utilized and it is easy to assemble and handle.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a first embodiment of the heating element of the present invention;
Figure 2 is a sectional view taken along the line ■-■ in Figure 1, and Figure 3 is a cross-sectional view taken along the line I in Figure 1.
-N line sectional view, FIG. 4 is the wiring type of this embodiment, FIG. 5 is a longitudinal sectional front view showing the second embodiment, FIG. 6 is a longitudinal sectional front view of the third embodiment, and FIG. This is a color chart comparing the temperature-time characteristics of the device of the first example with those of a comparative example. Explanation of symbols, 1... Ceramic heater,
11... Upper periphery, 12... Recessed part,
13...Thick film resistor pattern, 14.15...
... Lead-out pad, 16 ... Shaft hole, 2 ...
...Positive characteristic thermistor element, 20...Element body, 21...Negative electrode, 22...Positive electrode,
23...Gap, 24...Positive electrode lead-out pad, 25...Negative electrode lead-out pad, 2
6...Conducting part, 27...Shaft hole, 3...
...Through hole conduction part, 31...Through hole, 4, 5...Electrode terminal, 6...
Mounting leg, E...Power supply.

Claims (1)

[Claims] 1 The cross section is bowl-shaped, and a desired shape is formed on the upper periphery 11.
A ceramic heater 1 provided with a thick film resistance pattern 13 having a width and thickness; and a positive temperature coefficient thermistor element 2 fixed in the recess 12 of the heater 1 and having a heat generating surface on the same side as the heater 1. A composite heating element characterized in that the heater 1 and thermistor element 2 are electrically connected in parallel,