JPH07123017B2 - Temperature detection element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a temperature detection element used for temperature detection of rice cookers, air conditioners, etc., or cooling water temperature detection of automobiles, etc.

<Prior Art> FIG. 18 shows an example of a conventional temperature detecting element using a combination of a temperature-sensitive magnetic material, a permanent magnet and a reed switch. In the figure, a permanent magnet 2 having the same cross-sectional shape is arranged on both sides of a cylindrical temperature-sensitive magnetic body 1, and a reed switch 3 is inserted and formed in a central hole portion of a combined portion thereof. The magnetic flux density B vs. temperature T characteristics of the temperature-sensitive magnetic substance 1 are normally closed type and normally open type temperature detection characteristics in which the magnetic flux density B sharply decreases at the Curie temperature T _C as shown in FIGS. 19 and 20. The device is obtained. The temperature-sensitive magnetic material 1 is Mn-Zn ferrite and its Curie temperature T _C
Can be arbitrarily determined by the material composition over a wide range of -40 ° C to + 200 ° C. When the ambient temperature is T _C or less, the magnetic flux of the permanent magnet 2 passes through the temperature-sensitive magnetic body 1, and the magnetic flux outside the permanent magnet flows into the reed piece of the reed switch 3 to turn on the contact.
On the other hand, when the temperature rises to reach the Curie temperature T _C , the temperature-sensitive magnetic substance 1 becomes non-magnetic, and the magnetic flux flowing through the temperature-sensitive magnetic substance 1 flows into the reed switch 3 side as leakage flux, and the permanent magnet 2 The magnetic flux that has flowed into the reed switch 3 from both outsides of the reed switch 3 cancels each other out, the magnetic flux applied to the reed switch 3 falls below the open magnetic flux density of the reed switch 3, the reed switch 3 contacts are turned off, and the temperature becomes T _C. Is detected. This temperature detecting element is a fixed-point operation type temperature detecting element whose operating temperature can be detected at the Curie temperature T _C of the temperature-sensitive magnetic body 1, and is inexpensive with little secular change.

<Problems to be Solved by the Invention> However, in general, the temperature detecting element detects the temperature at one point, and it is impossible to continuously detect the temperature like a thermistor. Therefore, it is possible to perform fixed point temperature detection and continuous temperature detection as in the example of a composite type temperature detection element in which the fixed point temperature detection element 10 that operates magnetically and the thermistor element 11 are combined on the same substrate 12 as shown in FIG. . However, although this type of temperature detecting element is suitable for a wide range of applications, it has the drawback that the number of elements is two and the cost is high.

<Means for Solving Problems> In the present invention, the lead pieces 31 and 3 are externally provided except for the above-mentioned drawbacks.
Cylindrical temperature-sensitive magnetic body 1 which is circumscribed by a reed switch 3 provided with 2 and has two terminals 6 and 7 drawn out to the outside by electrodes 4 provided on both sides or on the outer periphery. In the temperature detecting element in which the cylindrical permanent magnet 2 is provided in contact with both side surfaces of the lead, the lead pieces 31 and 32 and the terminals 6 and 7 are independently drawn out, or either one of the lead pieces 31 and 32 and the terminal is connected. This is a temperature detecting element in which either one of 6, 7 is electrically connected, or each of the lead pieces 31, 32 and each of the terminals 6, 7 are electrically connected.

<Operation> By providing the electrodes 4 and 5 on the temperature-sensitive magnetic substance 1 and pulling them out, and changing the connection of the lead pieces 31 and 32 of the reed switch 3, the temperature detecting element continuously detects the temperature at a single point even if the temperature changes. It can perform both functions of temperature detection.

<Embodiment> An embodiment of the temperature detecting element of the present invention will be described with reference to an external perspective view of FIG. 1 and an exploded external perspective view of FIG.

The temperature-sensitive magnetic body 1 of the present invention has a cylindrical shape, and electrodes 4 and 5 are provided on the entire both side surfaces by means such as baking of silver electrodes. Cylindrical permanent magnets 2 are magnetized in the axial direction on both sides of the temperature-sensitive magnetic body 1 and are combined so that the opposite poles oppose each other. The reed switch 3 is inserted in the hole. Lead wires are connected to a part of the outer peripheries of the electrodes 4 and 5 of the temperature-sensitive magnetic body 1 and are exposed to the outside as terminals 6 and 7. The temperature-sensitive magnetic substance 1 is an Mn-Zn ferrite material, and its magnetic flux density B vs. temperature T characteristic is that the magnetic flux density B sharply decreases at the Curie temperature T _{C as} shown in FIG. Has a semiconductor property, and its resistance R vs. temperature T characteristic has a tendency that the resistance value R exponentially decreases with respect to the temperature T as shown in FIG. The resistance value R is 5kΩ-100k at room temperature 24 ℃.
Ω, and the rate of change in resistance with respect to temperature changes is -4 to-
It is around 5%, has almost the same performance as a conventional thermistor, and can be used as an element for sufficiently continuous temperature detection.

From the magnetic circuit of the combination of the temperature-sensitive magnetic substance 1 and the permanent magnet 2, the Curie temperature T _C In the following the magnetic flux phi of the permanent magnet 2, as FIG. 5, as the magnetic flux of the temperature-sensitive magnetic body 1 phi ₁ becomes, It flows into the reed switch 3 from the outside of the permanent magnet 2, and since the magnetic flux density is higher than the perceptible magnetic flux density, the reed switch contact is turned on.

When the temperature rises and reaches the Curie temperature T _C , the magnetic flux that has passed through the temperature-sensitive magnetic substance 1 until now flows into the reed switch contact as leakage flux and the direction of the magnetic flux is opposite to that of the previous magnetic flux, as shown in FIG. Therefore, they cancel each other out, and the open magnetic flux density of the reed switch 3 becomes lower than that. Therefore, the reed switch 3 is turned off. Therefore, the operation of the conventional normally closed temperature switch with the detected temperature T _C shown in FIG. 19 is shown. Normal reed switch 3
Easy contact is 10W to 50W, and it is possible to directly disconnect the relay or heater.

On the other hand leads 6 and 7 detects the resistance value of the temperature-sensitive magnetic substance 1 itself, since its characteristics are shown in Figure 4, the Curie temperature T _C
It is possible to detect temperature continuously without depending on.

Therefore, in the temperature switch of the present invention shown in FIG. 1, fixed-point temperature can be detected from the lead pieces 31 and 32 with the completely same component structure, and if the circuit processing is performed using the terminals 6 and 7, continuous arbitrary temperatures can be obtained. A composite type temperature detecting element capable of detecting temperature can be realized.

FIG. 7 shows another embodiment of the present invention, in which the electrodes 4 and 5 of the temperature-sensitive magnetic substance 1 are provided at arbitrary two positions on the cylindrical side surface.
Lead wires are output from electrodes 4,5 and connected to terminals 6 and 7,
The resistance value of the temperature-sensitive magnetic substance 1 is detected by the terminals 6 and 7. In this case, since the electrodes 4 and 5 are protruded from the side surfaces, the electrode area is smaller than that of the embodiment shown in FIG. 2 and the lead wire can be easily taken out.

FIG. 8 shows another embodiment of the present invention, in which the terminal 7 is electrically connected to the lead terminal 31 of the reed switch 3.
As for the resistance value seen from the lead piece 32, the resistance of the temperature-sensitive magnetic body 1 and the lead pieces 31 and 32 of the reed switch 3 are connected in series.
Therefore, the temperature characteristics are as shown in Fig. 9, and the Curie T
_The resistance value suddenly becomes infinite at _C1 . Such resistance R
When the temperature-versus-T characteristic is used, for example, the characteristic has a limiter function at the temperature T _C1 , and there is an advantage that the limiter function processing circuit in the post-processing circuit is simplified.

FIG. 10 shows another embodiment of the present invention, in which the electrode 5 of the temperature-sensitive magnetic substance 1,
The terminals 6 and 7 from 4 and the lead pieces 31 and 32 of the reed switch are connected in parallel with each other, and the resistance R vs. temperature T characteristics seen from the combined terminals 61 and 71 are up to the Curie temperature T _C2 as shown in FIG. Indicates that the resistance value of the temperature-sensitive magnetic substance 1 appears at the terminals 6 and 7'at a temperature of T _C2 or more when the terminals are short-circuited.

FIG. 12 shows another embodiment of the present invention, in which nonmagnetic spacers 8 are arranged on both sides of the temperature-sensitive magnetic body 1. The operation of this type of magnetic circuit is as shown in FIG. 14, and when the temperature T and the Curie temperature T _C are T <T _C , the leakage magnetic flux φ ₄ from the spacer 8 and the external magnetic flux φ ₃ cancel each other out and the reed switch is operated. Three
, The contact is turned off, and when T ≧ T _C , the magnetic flux from the inside of the permanent magnets 2, 2 ′ becomes dominant as shown in FIG. 15, and the contact of the reed switch 3 is turned on. The characteristics of the combined resistance R and the temperature T are shown in FIG.

FIG. 16 shows the lead terminal 6 from the electrode in the embodiment of FIG.
7 is an example in which both are connected to the lead pieces 31 and 32 of the reed switch 3, and FIG. 17 is a temperature T characteristic diagram of the combined resistance R thereof.

<Advantages of the Invention> As described above, according to the present invention, a temperature sensor for continuous detection, such as a thermistor and a stable operation type temperature switch that performs switch operation at the Curie temperature as in the past, is used. Since one element has both functions without combining two elements, it is compact and inexpensive and the range of use is expanded.

[Brief description of drawings]

FIG. 1 is an external perspective view of an embodiment of the temperature detecting element of the present invention,
2 is an exploded perspective view according to FIG. 1, FIG. 3 is a characteristic curve diagram showing the relationship between changes in magnetic flux density and temperature of the temperature-sensitive magnetic substance used in FIG. 1, and FIG. 4 is FIG. Of characteristic curves showing the relationship between the resistance and the change in temperature, FIG. 5 and FIG.
FIG. 7 is an explanatory diagram showing the magnetic circuit and operation of the temperature detecting element according to the present invention, FIG. 7 is an external perspective view of another embodiment of the present invention, and FIG. 8 is an external perspective view of another embodiment of the present invention. FIG. 9 is the eighth
FIG. 10 is a characteristic curve diagram showing the relationship between changes in resistance between terminals and temperature in the embodiment shown in FIG. 10, FIG. 10 is a perspective view showing the appearance of another embodiment of the present invention, and FIG. 11 is a view showing the relationship between terminals in the embodiment shown in FIG. FIG. 12 is a characteristic curve diagram showing the relationship between changes in resistance and temperature, FIG. 12 is an external perspective view of another embodiment of the present invention, and FIG. 13 is a graph showing changes in resistance between terminals and temperature in the embodiment of FIG. Fig. 14 is a characteristic curve diagram showing the relationship, Fig. 14 and Fig. 15 are explanatory diagrams showing the magnetic circuit and operation of the temperature detecting element according to the embodiment of Fig. 12, and Fig. 16 is the other lead piece in the embodiment of Fig. 12. 17 is an external perspective view of an embodiment of a temperature detecting element in which a terminal and a terminal are connected, FIG. 17 is a characteristic curve diagram showing the relationship between changes in terminal resistance and temperature in the embodiment of FIG. 16, and FIG. FIG. 19 and FIG. 20 are external perspective views of an example of the temperature detecting element, and FIGS. 19 and 20 show changes in temperature and magnetic flux density in the temperature detecting element in FIG. Characteristic curve diagram showing
FIG. 21 is an external perspective view of an example of a composite type temperature detecting element in which a conventional temperature detecting element and a thermistor are combined. In addition, 1: temperature-sensitive magnetic material, 2: permanent magnet, 3: reed switch, 31,3
2: Lead piece, 4, 5; Electrode, 6, 7, 7 ': Terminal, 8: Spacer, 10:
Fixed point temperature detection element, 11: thermistor element, 12: substrate.

Claims (3)

[Claims] 1. Two terminals 6 and 7 are drawn out from electrodes 4 and 5 which are circumscribed to a reed switch 3 in which lead pieces 31 and 32 are drawn out and which are provided on both side surfaces or two outer peripheries. In the temperature detecting element in which a cylindrical permanent magnet 2 is provided in contact with both side surfaces of a cylindrical temperature-sensitive magnetic body 1, the lead piece 3
The temperature-sensitive magnetic body 1 is used as a temperature-sensitive element of a temperature-sensitive reed switch by individually drawing out two of the terminals 1 and 32 and two of the terminals 6 and 7 and detecting a fixed point temperature from the lead pieces 31 and 32. In addition to being used, the temperature-sensitive magnetic body 1 is also used as a temperature detecting element by continuously measuring the temperature by measuring the change in resistance value of the temperature-sensitive magnetic body 1 using the terminals 6 and 7. A temperature detecting element characterized by. 2. The temperature detecting element according to claim 1, wherein any one of the lead pieces 31 and 32 and one of the terminals 6 and 7 are electrically connected. 3. The temperature detecting element according to claim 1, wherein each of the lead pieces 31 and 32 and each of the terminals 6 and 7 are electrically connected.