JPS6025574Y2 - dew point hygrometer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a dew point hygrometer that utilizes the hygroscopicity of lithium chloride.

Some dew point hygrometers utilize the hygroscopicity of lithium chloride and are configured to measure humidity based on physical self-equilibrium characteristics.

FIG. 1 is an explanatory diagram of the configuration of an example of a conventional dew point hygrometer of this type.

In the figure, 1 is a porous layer impregnated with lithium chloride, which is formed into a cylindrical shape.

2 and 3 are heating wires made of gold wire, 4 are heating wires 2 and 3
5 is a temperature detection element, and 6 is an indicator connected to this temperature detection element.

In this structure, the porous layer 1 absorbs water and increases its electrical conductivity when the water vapor pressure of the surrounding gas becomes higher than that of the saturated lithium chloride solution, and conversely, when the water vapor pressure of the outside air decreases, it absorbs water. It has the property of emitting , and its electrical conductivity decreases.

Now, when the water vapor pressure of the surrounding gas increases with the AC power source 4 connected between the heating wires 2 and 3, the electrical conductivity of the porous layer 1 increases and the current flowing through it increases, causing chlorination due to self-heating. The temperature increases until the saturated vapor pressure of lithium and the water vapor pressure of the outside air are in equilibrium.

On the other hand, when the water vapor pressure of the outside air decreases, the electrical conductivity of the porous layer 1 decreases, and the temperature automatically decreases to the equilibrium point of the water vapor pressure.

The temperature at this equilibrium point corresponds to the dew point of the gas with which the porous layer 1 is in contact, and this equilibrium temperature is detected by the temperature detection element 5, and its detection force is expressed as a humidity value by the indicator 6. be instructed.

Dew point hygrometers with such a configuration have been used in the past, but this conventional device has the disadvantage that the overall configuration is large.

In order to eliminate this drawback, the applicant has developed and filed an application for a dew point hygrometer as shown in FIG.

In FIG. 2, 10 is a flat alumina substrate, and 11 is a comb-shaped electrode, which is formed on the substrate 10 by thick film printing.

12 is a porous layer formed of ceramic powder;
Impregnated with lithium chloride solution.

This porous layer is baked onto the electrode 11.

The electrode 11 and the ceramic layer 12 are made of the gold wire 2 explained in FIG.
(3) and corresponds to porous layer 1.

Reference numeral 10' denotes the same substrate as the alumina substrate 10, on which an electrode having the same structure as the electrode 11 and the same ceramic layer as the ceramic layer 12 are formed.

A pair of substrates 10 and 10' having such a configuration are attached to a mouth-shaped spacer 20 so as to face each other.

Reference numeral 30 denotes a temperature detection element made of a platinum thermometer, and this element is placed between the substrates 10 and 10' with a jacket 31 in between.

The AC power source 4 shown in FIG. 1 is connected between the electrodes 10 and 10', and the indicator 6 shown in FIG. 1 is connected to the detection element 30, but both are omitted from the diagram in FIG. has been done.

The hygrometer of FIG. 2 having such a configuration operates in the same manner as the device of FIG. 1, and the dew point can be measured by the temperature detection element 30.

A hygrometer with this configuration has a porous layer 12 compared to the device shown in FIG.
There is an advantage that the temperature sensing element 30 can be made smaller by forming it on the flat substrate 10.
Since the temperature of the layer 2' is directly detected, it responds too quickly to the temperature of the multilayer 12.12', and the fluctuation range until reaching a thermal equilibrium state due to moisture absorption and dehumidification is too large, resulting in a slow response settling time. The disadvantage is that there is a delay.

In particular, when a transistor is used as the temperature detection element 30, it can be made much smaller than when a platinum thermometer 30 is used, but on the other hand, the hunting phenomenon occurs significantly due to its sensitivity characteristics.

The present invention has been made in view of this point, and a perspective view of the embodiment is shown in FIG. 3, an X cross-sectional view of FIG. A Y cross-sectional view of the figure is shown.

In FIGS. 3 and 4, 40 is a metal pipe, and this pipe is attached to the spacer 20 between the substrates 10 and 10' so as not to come into contact with both substrates.

30 is a temperature detection element, and a transistor is used.

A transistor is used as a temperature detection element by utilizing the fact that the voltage between its base and emitter depends on temperature.

Note that the other elements have the same configuration as in Figure 2, so
The same reference numeral as in FIG. 2 will be used to omit further explanation.

In the humidity detector of the present invention shown in FIGS. 3 and 4 constructed in this way, the temperature detection transistor 30 is arranged inside the metal pipe 40, so that the porous layer 12.12' Since the temperature does not directly act on the temperature detection element 30, the fluctuation range until reaching a thermal equilibrium state due to moisture absorption and dehumidification is small, and therefore, according to the present invention, the device is compact and has improved rise characteristics and response characteristics. A hygrometer can be obtained with an extremely simple configuration.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the configuration of a conventional hygrometer, Fig. 2 is a perspective view showing a part of the dew point hygrometer in cross section to explain the present invention, and Fig. 3 is an illustration of the dew point hygrometer of the present invention. FIG. 4A is a cross-sectional view taken along the X line in FIG. 3, and FIG. 4 is a cross-sectional view taken along the Y line shown in FIG. 3. 10.10'... Board, 11.11'...
... Electrode, 12.12' ... Porous layer, 30.
...Temperature detection transistor, 40...
metal pipe.

Claims (1)

[Scope of utility model registration request] A pair of flat electrodes each having a porous layer of ceramic powder impregnated with a lithium chloride solution are placed facing each other with a mouth-shaped spacer interposed therebetween, and a metal pipe contained inside the temperature detection transistor is connected to the pair of flat electrodes. A dew point hygrometer, which is arranged insulated between electrodes, supplies an alternating current voltage to the electrodes, and measures humidity from the output current of a temperature detection transistor.