JPS6314209A - Temperature controller - Google Patents

Abstract

PURPOSE:To reduce the density of a current which flows in an electrolyte and to prevent an electric field corrosion phenomenon as much as possible by impressing the lead-out body of a thermosensible element with a voltage which is lower than the decomposition voltage of the electrolyte when the lead-out body is used as an electrode in the electrolyte. CONSTITUTION:The thermosensible element 1 is constituted by joining lead-out bodies 21 and 22 for electric feeding to both sides of a thermistor 7 and sealing the thermistor 7 and lead-out bodies 21 and 22 partially with borosilicate glass. The series circuit consisting of the element 1 and a reference resistor 4 is connected to a DC power source 4. A control circuit 5 inputs a signal from the element 1 and performs electric feeding control over a load 6 including a heat generation body on the basis of the voltage VS developed between the lead-out bodies 21 and 22. This voltage VS is set to <=1V according to the relation among the resistance value RS of the thermistor, the resistance value of the resistor 3, and the voltage of a power source 4 at 0 deg.C. The thermistor 7 decreases in resistance value RS when the temperature rises above 0 deg.C, so the voltage VS never rises above 1V. When the temperature is <=0 deg.C, the RS increases and the voltage rises above 1V, but water is frozen and ion activation is suppressed, so that electrolytic corrosion is not caused.

Description

[Detailed description of the invention] Industrial applications The present invention is applicable to household electrical appliances such as microwave ovens.

The present invention relates to a temperature controller used in sanitary appliances such as a toilet seat with a hot water washer, or equipment in which a part of the heat-sensitive sensor is separated from the control circuit part.

BACKGROUND OF THE INVENTION Conventionally, a thermistor has been generally used as a heat-sensitive sensor used in a temperature controller. The thermistor is Mn
, Co, Fe, Cu, and other transition metals are used as the heat-sensitive element, and Dumet wire or C
A lead-out body made of a P-wire or the like is provided, and the heat-sensitive element and a part of the lead-out body are wrapped in an electrical insulator such as glass or heat-resistant resin. Moreover, the temperature controller converts the change in the thermistor's specific resistance into voltage.

This voltage is incorporated into the control signal. Therefore.

A voltage is always applied to both ends of the drawer, and this voltage is generally set at a value of 3 to 12 V to prevent noise, malfunction, and ease of assembling the control circuit.

Problems to be Solved by the Invention However, the entire heat-sensitive sensor used in microwave ovens and the like is coated with enamel coating of phosphor resin or polyamide resin. However, the enamel film does not completely coat the sharp edges of the cut portion of the drawer. Furthermore,
When the solvent contained in the enamel evaporates and dries after coating, pinholes are created, and the film often peels off due to high-temperature stress, exposing the drawer.

Under such conditions, if food decomposition products containing salt adhere to the thermal sensor installed in the refrigerator, or if water vapor generated in the refrigerator condenses, the electrical resistance of the surface of the refrigerator 9 will drop significantly.

Since a voltage of 3 to 12 V is always applied to the heat-sensitive sensor, a shunt of electricity occurs between the two electrodes.

The metal of the material constituting the drawer body enters the pinhole portion and dissolves into the water droplets as metal ions, causing a complete galvanic corrosion phenomenon. This also applies to heat-sensitive sensors used in toilet seats with warm water washers and the like.

This corrosion phenomenon eventually causes the drawer to break, causing problems such as the temperature control function becoming impossible.

Means for Solving the Problems The present invention has been made to solve the above problems, and it is aimed at reducing the decomposition voltage of the electrolyte that occurs when the lead-out body of a heat-sensitive element is used as an electrode in the electrolyte. The following voltages are applied.

Effect: By doing this, the density of electrical ratios that contribute to corrosion is reduced.

Example An embodiment of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2 showing the configuration of this embodiment, 1 is a heat-sensitive element, and power supply drawers 21 are provided on both sides of the thermistor 7.
．． 22 and the thermistor 7 and both drawer bodies 21.
．． 22 is partially sealed with lead borosilicate glass.

A reference resistor 3 is connected to the lead-out body 22, and a series circuit consisting of the heat-sensitive element 1 and the reference resistor 3 is connected to a DC power source 4. Reference numeral 5 denotes a control circuit, which inputs the signal from the heat-sensitive element 1 and connects a load 6 including a heating element, etc., and controls the energization of the load 6 using a voltage signal generated between the two drawers 21 and 22. It is carried out based on. Also.

The voltage Vs generated between the two coil bodies 21 and 22 is set to be 1V or less based on the relationship between the resistance value Rs of the thermistor 7 at 0°C, the resistance value R of the reference resistor O, and the voltage E of the DC power supply 4. .

That is.

If E=5V and Rs/R=1/4 at 0°C, then V
So that s = IV......

Furthermore, since the resistance value Rs of the thermistor 7 decreases when the temperature rises above 0°C, the voltage Vs between the two drawer bodies 21 and 22 will not exceed 1°C at a temperature above 0°C.

When the temperature is below 0°C, the resistance value S increases and the voltage Vs
At this temperature, water freezes and ion activity is suppressed, so there is no practical problem of galvanic corrosion.

Next, the operation of the fifth embodiment will be described.

Figure 6 shows the actual measurement results of the relationship between the applied voltage and current density when a Zimet wire was immersed in 6% saline as an electrolyte, and the entire DC voltage was applied between the electrodes. .

According to the figure, the current density is small when the applied voltage is 1V or less, but increases suddenly when the applied voltage exceeds 1V.

Furthermore, ('i: When the applied voltage is increased, the current density increases exponentially.

Here, the residual voltage is between 0 and 1V, and t2V2°C is the region where electrode reaction occurs. The father point of both these areas Ed
This is called the gold decomposition voltage, and when it exceeds this decomposition voltage Ed, the density of the current flowing between the electrodes increases rapidly.

Therefore, when the decomposition voltage Ed exceeds 9, the anode of the electrode is severely consumed.

Although the decomposition voltage varies depending on the properties of the electrolyte, the material of the electrodes, and the temperature of the electrolyte, the actual measured value of the polysaline solution in this example at a temperature of 20° C. is 9 decomposition voltage Ed - t2V.

To confirm, we conducted an experiment using a thermistor 7 with a B constant of 4000 K, and found that the resistance value Rs of the thermistor 7 at a liquid temperature of 20 to 25°C was 172.5 to 1/6 of that at 0°C.
When the DC power supply voltage E=5V, both drawer bodies 21
, 22 (7) Voltage i1' Vs = 0.4~0
．． 45 V tel.

Furthermore, it takes 1 for the 0.4φ dim wire to corrode and break.
It took 000 hours.

Using the same 0.4φ Siemenoto wire, resistance value Rs/resistance value R=110.2. When the DC power supply voltage E = 5 V, the voltage Vs = 3.1 to 3.3 cm, and the Dumet wire corroded and broke in 4 to 5 hours.

Effects of the Invention (1) According to the present invention, the voltage applied between the inner drawers is set to be less than the decomposition voltage of the electrolyte when the drawers are used as electrodes in the electrolyte, thereby reducing the current flowing through the electrolyte. It is possible to obtain a temperature controller that can reduce the density and prevent electrolytic corrosion phenomena as much as possible.

[Brief explanation of drawings]

FIG. 1 is an electric circuit diagram of a temperature controller according to an embodiment of the present invention, and FIG. 2 is a sectional view of the heat-sensitive element. FIG. 3 is a characteristic diagram showing the relationship between applied voltage and current density in an electrolytic solution. 1... Heat sensitive element, 21.22... Drawer body, 6.
··resistance. 4...DC power supply, 5...control circuit, 6...load.

Claims (1)

[Claims] In a temperature controller consisting of a heat-sensitive element (1) and a control circuit (5) connected thereto, the voltage applied to the lead-out bodies (21, 22) of the heat-sensitive element (1) is applied to the lead-out bodies (21, 22) in an electrolytic solution. A temperature controller characterized in that the temperature is set to be lower than the decomposition voltage of the electrolytic solution when the temperature is lowered.