JPH112570A - Thermistor type temperature sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve heat conductivity of a thermistor type temperature sensor. SOLUTION: An upward protrusion 16 is formed at a top plate part of an elevating case 10, and a thermistot element 22 is held to the inner surface of the protrusion 16. Accordingly, when a heated container C such as a pan on a cooker, the elevating case 10 descends against a spring 17 due to weight, and the protrusion 16 of the elevating case 10 is brought into pressure contact with the lower face of the heated container C by the biasing force. Contact area in therefore reduced, and the biasing force of the spring 17 is concentrated on the contact face of the protrusion 16, so that a part closest to the thermistor element 22 positively comes in contact with the heated container C so as to positively receive heat. Only the protrusion 16 is made a heat conductive face to the elevating case 10, and heat conduction is concentrated to improve conduction speed. Furthermore, even though the lower face of the heated container C such as the pan is uneven, a nearly point contact state is obtained by the protrusion 16, and even in case the pan bottom is deformed, heat conduction is not dispersed, so that heat is transmitted efficiently to the thermistor element 22.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermistor type temperature sensor which is most suitable for controlling the stop of heating of a gas stove, an electric heater or the like.

[0002]

2. Description of the Related Art As shown in FIG. 5, various types of thermistor type temperature sensors S (1) which are attached to the center of a gas burner B such as a gas stove A and used for controlling the stop of heating are proposed. This thermistor type temperature sensor S
(1) An upper part of a base tube fixed to the gas burner B is supported by an upwardly urged elevating case having a built-in thermistor element by a spring. When a non-heated container C such as a kettle is hung, the upper surface of the elevating case resiliently contacts the bottom surface to secure contact. By using a heating stop function such as shutting off the power supply of the air conditioner, it is attempted to prevent accidents such as generation of empty cooking, spilling due to heating, or gas leakage caused by extinguishing the fire due to spilling. Various thermistor-type temperature sensors having such a configuration have been proposed, such as Japanese Utility Model Publication No. 5-41385, Japanese Patent Application Laid-Open Nos. 57-14727 and 57-147278.

[0003]

SUMMARY OF THE INVENTION The above-described configurations are described in FIG.
As shown in the figure, the side surface of the storage tube c is joined to the inner surface of a flat top plate b formed at the top of the elevating case a, and the thermistor device s is inserted into the tube from the side. Then, it was held with a material such as silicon grease.

The elevating case a can be made of a metal material having good thermal conductivity, such as copper, phosphor bronze, or brass, in order to improve the responsiveness of the temperature sensor. It is disadvantageous in that it is easy and has poor durability.
On the other hand, in order to improve corrosion resistance, it is conceivable to form the elevating case a from stainless steel. However, stainless steel has a problem of poor thermal conductivity.

An object of the present invention is to improve the thermal conductivity by other means to propose a configuration which does not hinder the response even if stainless steel is used as well as copper, phosphor bronze and brass. Is what you do.

[0006]

SUMMARY OF THE INVENTION According to the present invention, an elevating case is supported on an upper part of a base tube attached to a fixed portion so as to be able to move up and down. In a thermistor-type temperature sensor that is biased upward and further holds a thermistor element on the inner surface of the top plate of the elevating case, a projection is formed on the top plate of the elevating case so as to project upward. A thermistor-type temperature sensor, wherein the thermistor element is held on an inner surface.

In this thermistor type temperature sensor, an overhead lift case is disposed so as to slightly project upward at the center of a gas burner of a gas stove or at a required position of an electric heating appliance. And, in the state of being arranged in this way, if a heated container such as a pan is hung on the stove, the lifting case descends against the spawn by weight,
The urging force causes the protrusion of the elevating case to press against the lower surface of the stove. If the container to be heated is overheated, the heat of the container is conducted to the thermistor element, the temperature of the thermistor element rises, and the resistance value of the container drops significantly. Therefore, when the resistance value becomes equal to or less than the predetermined threshold value, the heating stop function is activated, and the heating operation of the stove is stopped. That is, in the case of a gas stove, the release of gas is automatically cut off, and in the case of an electric stove, the switch is automatically turned off. Thereby, gas leakage, empty cooking, and boiling over can be prevented.

In the thermistor type temperature sensor according to the present invention, the projection formed on the top plate of the elevating case contacts the lower surface of the container to be heated such as a pan. For this reason,
The contact area is reduced, and the urging force of the projection is concentrated on the contact surface of the projection. For this reason, the portion closest to the thermistor element is pressed against the container to be heated, and the contact is secured.
The heat will be reliably received. Also, the heat conduction surface to the lifting case is only the protrusion, and heat conduction is concentrated, and the conduction speed is improved. Furthermore, even if there are irregularities on the lower surface of the container to be heated such as a pan, the protrusions make a point contact state substantially,
Even if the pot bottom is deformed, there is no hindrance to heat conduction. Thus, physical contact with the bottom surface of the container to be heated is ensured, and thermal conductivity is improved. Therefore, even if the elevating case is made of stainless steel, there is no problem in responsiveness.

When a hemispherical projection is used as the projection, point contact with the container to be heated is maintained, and heat conduction can be performed more quickly.

It is proposed that the thermistor element is fixed to the inner surface of the projection with a conductive paste.
In this case, the thermal conductivity is not impaired by the bonding material of the thermistor element.

[0011]

1 and 2 show a thermistor-type temperature sensor 1 according to an embodiment of the present invention. The thermistor-type temperature sensor 1 comprises an outer casing composed of a base tube 2 attached to a gas stove A (see FIG. 5) and the like, and an elevating elevating case 10 supported on the upper part so as to be able to ascend and descend. In the elevating case 10, a temperature sensing unit 20 having a built-in thermistor element 22 is provided.

Here, the base tube 2 is formed by connecting the main tube 3 and the connection tube 4 by caulking 5, and the upper part of the main tube 3 is enlarged to form a spring seat. Section 6 At the lower part of the connection pipe part 4, a locking projection 7 which engages with the mounting part D of the gas stove A is provided around.

The elevating case 10 is externally fitted to the spring seat 6 and is held up and down with respect to the spring seat 6. Here, the lifting case 10 is connected to the joining flange 1 at the upper end thereof.
1 and the reduced diameter lower part 12 at the lower end are circular in cross section,
The main cylinder portion 13 has a hexagonal shape, and the spring seat portion 6 of the main tube portion 3 also has a hexagonal shape of the same shape loosely fitted inside the main cylinder portion 13 of the elevating case 10, whereby the elevating case 10 is
It cannot rotate with respect to the base tube 2. in this way,
By preventing the rotation of the elevating case 10, it is possible to prevent the conductive wires 23, 23 coated with the coating tubes 27, 27, which will be described later, from being twisted to cause breakage or poor connection.

A dish-shaped cap 15 is joined to the joining flange 11 of the elevating case 10 so that the elevating case 1
0 is formed. The cap 15 is formed by molding a thin metal plate (SUS304 having a thickness of 0.3 mm) thinner than the main cylinder 13 (SUS304 having a thickness of 0.4 mm). The lower end of the cap 15 is circumferentially rolled and crimped to the bent edge so that the cap 15 is folded.
And the main cylinder 13 are combined to form the lifting case 10.

A hemispherical projection 16 according to the main part of the present invention projects upward from the top plate 10f of the lifting case 10 formed by the cap 15. A temperature sensing unit 20 is joined to the inner surface of the hemispherical projection 16 of the cap 15. A spring 17 is provided between the inner top surface of the cap 15 and the seating surface of the spring seat portion 6.
0 is biased upward. By this biasing, the step between the main cylindrical portion 13 and the reduced diameter lower portion 12 of the elevating case 10 comes into pressure contact with the step surface generated by the spring seat 6 of the base tube body 2 from below, and the elevating case 10 The normal position (the highest position) with respect to the base tube 2 is defined.

Next, the structure of the temperature sensing unit 20 attached to the hemispherical projection 16 according to the present invention will be described with reference to FIG.
This will be described in more detail. The temperature sensing unit 20 includes a sensor tube 21 which is opened up and down and has a fixing flange 24 projecting outward at an upper end thereof.
3 (0.35φ) has a built-in thermistor element 22 drawn out, and a gap between the sensor cylinder 21 and the thermistor element 22 is filled with a sealing material 26. The upper end of the thermistor element 22 is hemispherical, and the radius of the hemispherical projection 16 is larger than the diameter of the upper end of the thermistor element 22, and the top end of the thermistor element 22 is located on the inner surface of the hemispherical projection 16. Point contact is made possible. This point contact is ensured by the conductive paste 25.

An assembling procedure of such a configuration will be described. First, the top end of the thermistor element 22 is adhered to the inner surface of the hemispherical projection 16 of the cap 15 with a conductive paste 25 such as a silver paste or a copper paste, so that the thermistor element 22 is maintained in a state of maintaining point contact. I do. Next, the sensor cylinder 21 is externally fitted to the thermistor element 22,
The fixing flange 24 is joined by means such as spot welding. Further, the sealing material 26 is filled in the sensor cylinder 21. As the sealing material 26, a material having good heat resistance and excellent heat conductivity, such as a mixture of aluminum nitride powder or alumina powder in heat-resistant alumina cement or polyimide resin, is suitably used.

The conductive wires 23 of the thermistor element 22 drawn out of the sensor tube 21 are made of a glass braid and covered with heat-resistant and wear-resistant coating tubes 27.
And the upper ends of the coating tubes 27, 27 are inserted into the sensor tube 21. Then, a temperature of 150 ° C. is applied for one hour to solidify the sealing material 26. After the sealing material 26 has solidified, the cap 15 is joined to the joining flange 11 of the elevating case 10 and assembled, and the coating tubes 27 and 27 are pulled out from the lower end of the main pipe portion 3.
At its tip, the conducting wires 23, 23 in the coating tubes 27, 27
And the conductors 29, 29 of the connector 28 are connected via the connection material 30. After that, the connecting pipe part 4 in which a part of the connecting material 30 and the conductive wires 29 and 29 are inserted is provided on the inner surface of the lower end of the main pipe part 3.
The outer circumference of the upper end is fitted, and caulking 5 is performed to connect both pipes.

The thermistor-type temperature sensor 1 thus configured engages the locking projection 7 of the connecting pipe 4 with the mounting portion D of the gas stove A, and is positioned at the center of the gas burner B of the gas stove A. Then, the connector 28 is connected to a required control circuit device. At the time of this attachment, the lifting case 10
Is positioned slightly above the lower surface of the heated container C placed on the gas stove, and when the heated container C is placed, the elevating case 10 is Then, the top end of the hemispherical projection 16 of the elevating case 10 elastically contacts the lower surface of the container C to be heated.

When the heated container C is heated in this mounted state, the heat is transmitted from the top end of the hemispherical projection 16 to the thermistor element 22 directly or through the conductive paste 25. Then, a resistance change corresponding to the temperature occurs,
When the temperature falls below a preset threshold, the gas stove is turned off or the power supply of the electric heating appliance is cut off. As a result, accidents such as generation of empty cooking, spilling due to overheating, or gas leakage caused by fire extinguishing due to spilling can be prevented beforehand.

Incidentally, in the thermistor type temperature sensor of the present invention, the top end of the hemispherical projection 16 formed on the top plate of the elevating case contacts the lower surface of the heated container C such as a pot. Therefore, the urging force of the spring 17 is reduced to the hemispherical projection 1.
Concentrate on contact point 6. For this reason, the thermistor element 22
, The hemispherical projection 16 closest to is pressed against the heated container C,
A heat transfer path is reliably generated. Also, the heat conduction surface to the lifting case is only the protrusion, and heat conduction is concentrated, and the conduction speed is improved. Thus, physical contact with the bottom surface of the container to be heated is ensured, and thermal conductivity is improved. For this reason, even if the elevating case is made of stainless steel, it can be sufficiently used.

FIGS. 3A and 3B show the cap 15
Is formed of stainless steel (SUS304, 0.3 mm in thickness) and does not use the hemispherical projection 16 (a), and the thermal conductivity of the product of the present invention (b) using the hemispherical projection 16 is compared. It is. Here, the time (thermal time constant) until the resistance value stabilizes when contacted with the container C heated to 180 ° C. was compared. As a result, as can be seen from FIG.
Second, which is 8 seconds for the product of the present invention, which indicates that the thermal time constant was greatly improved. It is understood that the formation of the hemispherical projections 16 improves the thermal conductivity.

When the hemispherical projections 16 are formed as described above, the contact is ensured by the hemispherical projections 16. There is an advantage that heat is not hindered even if the pot bottom is almost in a point contact state and the pot bottom is deformed.

Further, in the above configuration, since the thermistor element 22 is held by the conductive paste 25 so that the top end thereof is in contact with the inner surface of the hemispherical projection 16, it is possible to obtain faster heat conduction. And the conductive paste 25 has good thermal conductivity.
Heat conduction through 5 is also expected. By the way, in the above-mentioned configuration, the hemispherical projection 16 is provided so as to make point contact with the container C to be heated. However, as shown in FIG. Protrusions of various shapes, such as conical or truncated conical, are proposed. These are all
The heated container C and the elevating case 10 can be brought into almost point contact.

[0025]

As described above, according to the present invention, the protrusion 16 (16 ') is formed on the top plate 10a of the lifting case 10 upward, and the thermistor element is provided on the inner surface of the protrusion 16 (16'). When holding the container C to be heated such as a pan on the stove, the lifting case 10 descends against the spout 17 by weight, and the urging force causes the lifting case 10 to be placed on the lower surface of the container C to be heated. The ten projections 16 (16 ') are pressed against each other. For this reason, the contact area is reduced, the biasing force of the ridge 17 is concentrated on the contact surface of the projection, and the portion closest to the thermistor element 22 reliably contacts the heated container C and receives heat reliably. Becomes Also, the heat conduction surface to the lifting case 10 is only the protrusion 16 (16 '), and heat conduction is concentrated.
The conduction speed is improved. Furthermore, even if the lower surface of the heated container C such as a pan has irregularities, the projections 16 (16 ')
Even when the bottom of the pot is deformed substantially in a point contact state, heat conduction is not dispersed and heat is efficiently transmitted to the thermistor element. Thus, physical contact with the bottom surface of the heated container C is ensured, and the thermal conductivity is improved. For this reason, even if the elevating case 10 is formed of stainless steel, the thermal responsiveness is not impaired, and it is possible to optionally use a metal that is slightly inferior in heat conductivity but has good corrosion resistance.

Further, as the projection, a hemispherical projection 1 is used.
By using 6, the point contact with the container C to be heated is maintained, and the heat conduction can be made faster.

Further, when the thermistor element 22 is fixed to the inner surface of the projection 16 (16 ') with the conductive paste 25, heat conduction through the conductive paste 25 is expected, and the thermistor element 22 is fixed. The material used for bonding does not impair the thermal conductivity.

[Brief description of the drawings]

FIG. 1 is a vertical sectional side view of a thermistor type temperature sensor 1. FIG.

FIG. 2 is an enlarged vertical sectional side view of a main part.

FIG. 3 is a graph showing a heat conduction characteristic (a) of a configuration not using a hemispherical projection 16 and a heat conduction characteristic (b) of the product of the present invention.

FIG. 4 is a longitudinal sectional side view of a main part showing a projection 16 'of another configuration.

FIG. 5 is a conceptual diagram showing an assembled state of a thermistor type temperature sensor 1 on a gas stove.

FIG. 6 is a vertical sectional side view showing a conventional configuration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermistor type temperature sensor 10 Elevating case 15 Cap 16, 16 'Protrusion part 20 Temperature sensing part 21 Sensor cylinder 22 Thermistor element 25 Conductive paste 26 Sealing material

Claims (3)

[Claims] 1. An upper part of a base tube attached to a fixing part,
The elevating case is supported so as to be able to ascend and descend, and is urged upward by a spring provided between the elevating case and the base tube. Further, the thermistor element is held on the inner surface of the top plate of the elevating case. A thermistor-type temperature sensor, characterized in that a projection is formed on a top plate of an elevating case and protrudes upward, and the thermistor element is held on an inner surface of the projection. 2. The thermistor-type temperature sensor according to claim 1, wherein said protrusion is a hemispherical protrusion. 3. The thermistor-type temperature sensor according to claim 1, wherein the thermistor element is fixed to an inner surface of the projection with a conductive paste.