JPS6359085B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a temperature sensor used in cooking utensils, combustion equipment, etc., and provides a temperature sensor that has a simple structure and is resistant to dirt and condensation. .

Structure of the conventional example and its problems As shown in Fig. 1, the conventional temperature sensor has a pair of opposing rod-shaped lead wires (Kovar rod: φ1. 6) A lead wire connection terminal consisting of 3 is used, and the thin film thermistor chip is connected to a temperature sensing element body 4 including a temperature sensing resistor film formed on the surface of a flat insulating substrate and a pair of internal lead wires 5 (about φ0.15). platinum
It is composed of a thin Pt wire or a thin gold-Au wire, and is sealed inside a glass tube 6. Furthermore, an external lead wire 7 such as a Kovar wire (about φ0.5) and an internal lead wire 5 are connected. 6 and the external lead wire 7 is firmly connected to the rod-shaped lead wire connection terminal 3.

The reason why the thin film thermistor chip is tightly sealed with the internal lead wire 5 and the external lead wire 7 in the glass tube 6 is as follows.
This is because connecting the thin film thermistor chip to the lead wire connection terminal 3 using the thin metal wire of the internal lead wire 5 had the drawback of low mechanical strength.
Therefore, in the structure of the glass tube 6, the internal lead wire 5 is protected from external mechanical stress, and even a thin metal wire has sufficient practicality.

Further, the external lead wire 7 is also mechanically and firmly connected to the lead wire connecting terminal 3, and there is no problem in practical use. However, this configuration has the drawbacks of a complicated structure, poor workability, high cost, and slow thermal response due to its large heat capacity.

FIG. 2 is a sectional view of the conventional temperature sensor shown in FIG. 1 attached to a combination product of a microwave oven and a microwave oven. FIG. 3 is an enlarged sectional view of the temperature sensor section.

8 is a bottom plate, 9 is a roasting box whose front opening is opened and closed by a front door 10, and a circulation inlet 12 is formed in the back wall 11 of the roasting box. A heat source case 13 is separate from the roasting box 9 and is attached to the back of the roasting box 9 via screws, in which a sheathed heater 14 and a fan 15 are housed. 16 is a motor that drives the fan;
17 is a cooling fan, and 18 is a screw for attaching the fan 15 to the motor shaft. 19 is a magnetron provided outside the roasting box 10; 20 is a waveguide; 21
2 shows a ceramic dish for microwave oven, and 22 shows a cooked food. The temperature sensor is attached to the top surface of the roasting box 9 through screws to the mounting bracket 1, and is covered with a sensor cover 24 having an air hole 23. Other control parts etc. are omitted.

The lead wire connection terminal 3 of the temperature sensor is connected to a control circuit (not shown) via a lead wire. The internal temperature of the roasting box 9 is controlled by detecting a change in resistance of a thin film thermistor chip of a temperature sensor, which poses a problem of malfunction, especially when the oven is used after the microwave oven has been used.

This is because when the device is used, oil, soy sauce, food scraps, etc. 25 from food adhere to the temperature sensor's ceramic insulator 2, mounting bracket 1, lead wire connection terminal 3, glass tube 6, and external lead wire 7. .

When the food 22 is heated in a microwave oven, the inside of the roasting box 9 is filled with steam from the food 22 and condenses.
Each part of the temperature sensor is also covered with condensed water 26, the lead wire connecting terminal 3 is connected with the dew condensed water 26, and the lead wire connecting terminal 3, the roasting box 9, and the external lead wire 7 are connected with the dew condensed water 26. It's connected.

When used as an oven, even if the thin film thermistor chip detects a normal resistance value, condensation water
As a result, the resistance value going to the control circuit changes significantly and becomes a very small resistance value. In other words, a malfunction will occur.

Conventional temperature sensors are susceptible to dirt (oil from food, soy sauce, salt, food particles, etc. 25 tend to adhere to them). It also has the disadvantage of being weak against dirt and dew condensation (water droplets tend to connect) easily.

OBJECTS OF THE INVENTION The present invention provides a temperature sensor that overcomes the drawbacks of conventional constructions and is resistant to dirt and condensation.

Structure of the Invention In order to achieve the above object, the present invention has a pair of opposing flat lead wire connection terminals whose intermediate portions are fixed with an insulator, and an end of a thin film thermistor chip between the opposing lead wire connection terminals. The thin-film thermistor chip is wrapped in an alumina adhesive with a recess for accommodating the thin film thermistor chip, thereby providing a temperature sensor that is resistant to dirt.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 4 shows a perspective view of a temperature sensor according to an embodiment of the present invention. FIG. 5 is an enlarged perspective view of the thin film thermistor section, and FIG. 6 is an enlarged partial sectional view of the sensor attached to a device.

A pair of opposing flat lead wire connection terminals (SOS430-0.6) 28 are fixed in the middle with a ceramic insulator 27 equipped with a mounting bracket 1, and a recess 29 is provided in the lead wire connection terminal portion on the opposite side. There is.
The thin film thermistor chip has a temperature sensing element of 4 (2 mmW x 7
mmL×0.8t) and an internal lead wire 5. The recess 29 was designed to accommodate the end of the thin film thermistor chip (2.5 mmW x 3mmL x 0.8mmt). This recess 29 can be easily formed by drawing.
The internal lead wire 5 and the flat lead wire connection terminal 28 are connected by spot welding. Further, an alumina-based reinforcing agent 30 is applied to the recess 29 to cover the thin film thermistor chip and internal lead wire 5 and firmly fix them. In addition, the thin film thermistor chip part, the lead wire connection terminal 28 and the mounting bracket 1,
The entire ceramic insulator 27 is coated with a tetrafluoroethylene (trade name: Teflon, etc.) based resin 31. As this coating agent, one having water repellency is used.

A drop test (1 m
We conducted a vibration test (free fall from a height of , there is no problem at all.

Furthermore, if the thin film thermistor chip is entirely wrapped in the alumina reinforcing agent 30, the thermal response can be slowed down, and the thermal response can be arbitrarily determined.

Next, let's talk about dirt and condensation. The temperature sensor of this example is coated with a water-repellent surface treatment, so it is free from oil, soy sauce, and salt from food.
Food scraps etc. 25 are less likely to stick. Also, roasting box 9
Even if the inside is filled with water vapor, the temperature sensor is coated with a water-repellent surface treatment, so it will repel water, and the water will exist as water beads 32, so water will not seep into the inside. In other words, water is not connected between the lead wire connection terminals 28 of the ceramic insulator 27 of the temperature sensor, between the thin film thermistor chip, and between the lead wire connection terminal 11 and the roasting box 9, and the thin film thermistor chip normally detects resistance and controls the temperature sensor. It is transmitted to the circuit, so there is no problem of malfunction. In addition, it is made of tetrafluoroethylene and can withstand high temperatures, causing no problems in actual use.

Effects of the Invention According to the present invention, it is possible to provide a temperature sensor with a simple structure, good workability, low cost, and good thermal responsiveness.Moreover, the thermal responsiveness can be arbitrarily determined, and it is also resistant to dirt. By applying a water-repellent coating to a conventional temperature sensor, a temperature sensor that is resistant to dirt and condensation can be provided.

[Brief explanation of the drawing]

Figure 1 is an external perspective view of a conventional temperature sensor;
The figure is a cross-sectional view of the sensor attached to a heating cooker, FIG. 3 is an enlarged cross-sectional view of the sensor attachment part, FIG. 4 is an external perspective view of a temperature sensor that is an embodiment of the present invention, and FIG. FIG. 6 is an enlarged perspective view of the thin film thermistor portion of the sensor, and FIG. 6 is an enlarged sectional view of the main part showing the sensor attached to a cooking appliance. 4... Temperature sensitive element (thin film thermistor chip), 2
7... Ceramic insulator, 28... Lead wire connection terminal, 29... Recessed portion, 30... Alumina adhesive, 31... Tetrafluoroethylene resin having water repellency.

Claims (1)

[Scope of Claims] 1. A recessed portion having a pair of opposing flat lead wire connecting terminals whose intermediate portions are fixed with an insulator, and storing an end portion of a thin film thermistor chip between the opposing lead wire connecting terminals. A temperature sensor having a structure in which the thin film thermistor chip is wrapped with an alumina adhesive. 2. The temperature sensor according to claim 1, in which the thin film thermistor chip, lead wire connection terminal, insulator, etc. are coated with resin. 3. The temperature sensor according to claim 2, wherein the resin coating is made of a tetrafluoroethylene resin having water repellency.