JPS617457A - Humidity sensor - Google Patents

Abstract

PURPOSE:To prevent deterioration by adhesion of such inorganic solid particles as salt grains, dust, etc., by making a humidity sensitive unit contained in a box and setting on opening in the box within a cubic angle of 1/1,000-1/10 radian from the humidity sensitive unit. CONSTITUTION:A humidity sensitive unit 1 for detection of humidity is heated by a cleaning heater 2 and a humidity electric signal is lead out by an electrode 3. Humidity sensitive unit 1, heater 2, electrode 3 are accommodated in a box 4 in a bottomed cylinder and covered by a supporting unit 5. In this box 4, a slit- shaped opening 6 is formed within a cubic angle of 1/1000-1/10 radian from the humidity sensitive unit 1 or central part of the box 4. By providing such an opening, deterioration by such inorganic solid particles as salt grains and dust, etc. without giving horm to responsivity of the humidity sensitive material itself.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a humidity sensor used for measuring or controlling humidity.

Conventional configurations and their problems In recent years, the need for humidity sensors has increased in various industrial fields including the air conditioning field, but there are many problems with their reliability. In particular, reliability in a contaminated environment where salt particles, inorganic solid particles such as dust, etc. are present is a concern.

Hereinafter, the conventional humidity sensor as described above will be explained with reference to FIG.

FIG. 6 shows the configuration of a conventional heating cleaning type humidity sensor. The moisture sensing section 1, heater 2, electrode 3, holding section 6, and lead wire 7 have the same structure as in FIG. 1, so the same reference numerals are given and details will be omitted. Reference numeral 8 denotes a protector for protecting the contained moisture sensing section 1 and heater 2 from mechanical damage, and a large number of through holes 8a are provided around the protector to improve heat dissipation after heating and cleaning.

The operation of the humidity sensor configured as above will be described below.

In the above configuration, first, the humidity sensor is brought into contact with the measurement atmosphere. The water vapor in the atmosphere diffuses and reaches the humidity sensing part 1 by airflow and is adsorbed. The electrical characteristics of the humidity sensing section 1 are changed depending on the amount of adsorption at that time. This change can be detected electrically by applying a voltage to the electrode 3 via the lead wire 6 in advance, thereby allowing the humidity in the atmosphere to be detected electrically.

However, the above configuration has the following drawbacks. The first point is that if there are inorganic solid particles in the atmosphere that cannot be removed by heating cleaning, such as salt particles or dust, the inorganic solid particles can easily reach the moisture sensitive part or electrode through the through holes of the protector. This causes deterioration of the device and makes it impossible to reproduce it. The second drawback is that during heating cleaning, the heater reaches a high temperature of 50oC or higher, so if flammable substances are present in the atmosphere, there is a risk of explosion or fire, which poses a safety problem in use. It is.

Therefore, it is desired to develop a heated cleaning type humidity sensor that is highly safe and highly reliable even in environments where inorganic solid particles such as salt particles and dust, and explosive substances are present. There is.

Purpose of the Invention In view of the above-mentioned drawbacks, the present invention provides the following features without impairing safety:
SUMMARY OF THE INVENTION In order to achieve this object, a humidity sensor of the present invention is provided which has high reliability in a contaminated environment where inorganic solid particles such as salt particles and dust exist. is composed of a humidity sensing section, a heating section for the humidity sensing section, a holding section for the humidity sensing section and the heating section, and a casing that is combined with the holding section and contains the humidity sensing section and the heating section, and the casing And the opening connecting the inside and outside of the holding part has a solid angle of -1666- from the humidity sensing part or the center of the case.
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With this configuration, it is possible to protect the humidity sensing part from adhesion of salt particles and dust in the atmosphere, and provide a humidity sensor with excellent environmental resistance without compromising its safety. This will be explained with reference to the drawings. Figures 1a and 1b show the structure of a humidity sensor in an embodiment of the present invention. In Figures 1a and b, 1 is a humidity sensing section for detecting humidity, 2 is a cleaning heater for heating the id humidity sensing section, 3 is an electrode for converting humidity into an electrical signal, and 4 is a sensing section. It is a cylindrical case with a bottom that houses a wet part 1, a heater 2, and an electrode 3. The heater 2 is attached and the lid is closed with an oval holding part 5. This housing has a slit-shaped opening 6 formed therein. Then, the holding section 5
fixes the humidity sensing section 1 and heater 2. Dimension opening 6rri
This is for bringing the humidity sensing section 1 into contact with the atmosphere. The opening 6 is located below the humidity sensing section 1 and the electrode section 3, and the solid angle from the center of the humidity sensing section 1 or the housing 4 is set to be less than one. Reference numeral 7 denotes a lead wire for applying a 1° voltage and outputting a signal, which is led out from the electrode 3 and passes through the holding portion 6.

The operation of the humidity sensor configured as above will be described below.

In the above configuration, if the opening 6 is provided in a predetermined position with the opening 6 facing vertically downward, the moisture sensing part 1 and the electrode 3 are surrounded by the casing 4, and can only be accessed through the slit-shaped opening 6 located below them. It comes into contact with the atmosphere and detects humidity. In this way, inorganic solid particles such as salt particles and dust in the atmosphere can diffuse through the atmosphere like water vapor. It does not adhere to the electrode 3, but falls freely and is only deposited on the upper part of the housing 4.Also, even in the case of windy conditions, the humidity sensing part 1 and the electrode 3 are located above the opening 4; Furthermore, the solid angle of the opening is less than -radian, and it is configured so that only one side is provided in the direction of the wind, making it difficult for ventilation.
And it is difficult to be sensitive to electrode 3. In this way, the moisture sensing portion 1 and the electrode 3 are free from adhesion of the inorganic solid particles in any state. FIG. 2 shows the relationship between the solid angle of the aperture 6 and the deterioration of the sensor when seawater is sprayed from right side to the aperture 6 at a wind speed of about 0.56 m/s to the humidity sensor configured as described above. As shown in the figure, it can be understood that by setting the solid angle to 1 or less, the deterioration of the sensor due to salt during windy conditions can be significantly reduced.

On the other hand, water vapor in the atmosphere is adsorbed to the humidity sensing part 1 through the opening 6 by diffusion even in a windless state. At that time, its electrical characteristics are changed depending on the amount of adsorption.

The amount of change is converted into an electrical signal by the electrode 3 to which a voltage is applied via the lead wire 7. In this way, the humidity of the atmosphere can be detected without adhesion of inorganic solid particles in the atmosphere and without compromising safety.

Figures 3a and 3b show a second embodiment of the invention. Since the humidity sensing section 1, heater 2, electrode 3, housing 4, holding section 6, and Riet wire end are the same as those in the second embodiment, they are given the same reference numerals and detailed explanations will be omitted.

The difference from the above embodiment is that the opening 6 as shown in FIGS.
It's in a. That is, the opening 6a is provided not in the housing 4 but in the holding portion 5.

Regarding the humidity sensor configured as above, the following r(
The operation will be explained.

In the above configuration, the humidity detection operation is the same as that in the above embodiment, so a description thereof will be omitted. The difference from the above embodiment is that an opening 6 is provided in the holding part 5. By doing so, the humidity sensing section 1 and the electrode 3 are completely covered with a casing without an opening, so that they are not affected much by the surrounding air flow condition and can be avoided from adhesion of inorganic solid particles. Also, this opening 6
If this hole is also used as the through hole for the power line 7, it will be advantageous in manufacturing the sensor.

As described above, according to this embodiment, by providing the holding portion 5 in the opening 6a, it is possible to prevent element deterioration due to attachment of inorganic solid particles without being affected by the surrounding airflow state.

In the above embodiment, the opening 6 is provided in the form of a slit on the side surface of the casing 4, but the installation position, shape, number, and arrangement of the opening 6 are determined by changing the solid angle of the opening from □ to □. As long as it is limited to the range of , it may be provided as shown in FIGS. 4 and 5. That is, Figure 4a
In this case, openings 6b are provided in two rows in the vertical direction on the side surface of the housing 4. In FIG. 4, the openings 6b are arranged in one row. Figure 4C
The openings 6c are arranged in a cross shape. In FIG. 6, an opening 6d is provided on the top surface of the casing 4.

Furthermore, if the width of the opening 6 in the above embodiment is set to 1 column or less, the casing 4 can also serve as an explosion-proof structure as it is, and flammable substances are not present around it during heating cleaning. However, the risk of explosion can be avoided.

Effects of the Invention As described above, in the present invention, the moisture sensing part and the electrode are housed in the housing, and the solid angle is 10 to 1 degree. . By providing a moderate opening in the casing or holding portion, it is possible to prevent deterioration due to adhesion of inorganic solid particles such as salt particles and dust without significantly impairing the responsiveness of the moisture-sensitive material itself. Furthermore, the opening is 1'
By setting the temperature to about yn or less, an explosion-proof structure can be imparted to the casing, fires and explosions can be prevented during heating cleaning, and safety in use can be ensured.

[Brief explanation of the drawing]

FIG. 1a is a partially cutaway vertical cross-sectional view showing the configuration of a humidity sensor according to an embodiment of the present invention, FIG. 1 is a cross-sectional view of FIG. 1d, and FIG. 2 is a humidity sensor of FIG. A graph showing the relationship between the solid angle of the aperture and element deterioration when seawater is sprayed on the surface, and FIG. Figure 3 is a bottom view of Figure 3a, Figure 4 is a, b, 'C, and Figure 6 is a side view of an example of changes in the shape, number, arrangement, and installation position of the openings in Figure 1, and the main part is broken. 6A and 6B are a partially broken longitudinal sectional view and a cross sectional view showing the structure of a conventional heating cleaning type humidity sensor. 1... Moisture sensing section, 2... Heater, 3... Electrode, 4... Housing, 5... Holding section, 6... Opening. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure tα) / (b) Figure 2 MUchh414, S"X/ρ"5 (Runamp Figure 3

Claims (6)

[Claims] (1) A humidity sensing part having an electrode, a heating part of the humidity sensing part, a holding part of the humidity sensing part and the heating part, and a casing that is combined with the holding part and contains the humidity sensing part and the heating part. The solid angle from the humidity sensing part or the center of the housing is 1.
Humidity sensor in the range of /1000 to 1/10 radian. (2) Claim 1 in which the width of the opening is 1 mm or less
Humidity sensor as described in section. (3) The humidity sensor according to claim 1, wherein the opening is a slit. (4) The opening is composed of multiple through holes, and its solid angle is
The humidity sensor according to claim 1, wherein the outer lines of the plurality of through holes are connected. (5) The humidity sensor according to claim 1, wherein the opening is provided at the top of the casing. (6) The humidity sensor according to claim 1, wherein the holding portion is provided with an opening.