JPH0554625B2 - - Google Patents

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 5, and lead wire 7 have the same structure as in FIG. 1, so the same reference numerals are given and details are omitted. 8 is the contained humidity sensing part 1 and heater 2
with a protector to protect it from mechanical damage,
A large number of through holes 8a are provided around the periphery to improve heat dissipation after heating and cleaning.

Regarding the humidity sensor configured as above,
The operation will be explained below.

In the above configuration, first, the humidity sensor is brought into contact with the measurement atmosphere. Water vapor in the atmosphere reaches the humidity sensing section 1 by diffusion or airflow and is adsorbed therein. The moisture sensing section 1 changes its electrical characteristics 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 such as salt particles or dust that cannot be removed by heating cleaning in the atmosphere, the inorganic solid particles can easily pass through the through holes of the protector to the moisture sensitive part or the electrode. This causes deterioration of the device and makes it impossible to reproduce it. The second drawback is that during heated cleaning, the heater reaches a high temperature of over 500°C, so if flammable substances are present in the atmosphere, there is a risk of explosion or fire, which poses a safety problem. .

Therefore, it is desired to develop a heat-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.

Purpose of the Invention In view of the above drawbacks, the present invention provides a heated cleaning type humidity sensor that has high reliability in a contaminated environment where inorganic solid particles such as salt particles and dust exist without compromising safety. It is something.

Structure of the Invention In order to achieve this object, the humidity sensor of the present invention includes a humidity sensing part, a heating part of the humidity sensing part, a holding part of the humidity sensing part and the heating part, and a humidity sensing part coupled to the holding part. An opening connecting the inside and outside of the casing and the holding part is provided on one side of the casing, and the opening is connected to the humidity sensing part or the casing with a solid angle from the center of the casing. It is designed to have a size not exceeding 1/10 steradian.

With this configuration, it is possible to protect the humidity sensing section from adhesion of salt particles, dust, etc. in the atmosphere, and to provide a humidity sensor with excellent environmental resistance without impairing its safety.

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

FIGS. 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 humidity sensing section, 3 is an electrode for converting humidity into an electrical signal,
Reference numeral 4 denotes a cylindrical case with a bottom that houses the humidity sensing section 1, the heater 2, and the electrode 3, and is closed with a circular holding section 5 to which the heater 2 is attached. This housing forms a slit-shaped opening 6. The holding section 5 fixes the humidity sensing section 1 and the heater 2. Further, the opening 6 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 1/10 or less.
7 is a lead wire for voltage application and signal output;
It is led out from the electrode 3 and penetrates the holding part 5.

Regarding the humidity sensor configured as above,
The operation will be explained 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, especially salt particles (sea salt particles) that affect life performance due to salt damage, are heavy and mainly settle due to gravity, and are removed from the atmosphere like water vapor. Since it cannot move by diffusion, it is difficult to enter through the opening 6 in a windless state and is difficult to adhere to the humidity sensing part 1 and the electrode 3. Also, in the case of wind, the humidity sensing part 1 and the electrode 3 should be located above the opening 4, the solid angle of the opening should be 1/10 steradian or less, and only one side of the opening should be provided in the wind direction, making it difficult to ventilate. Even if wind were to blow from vertically upward, it would be difficult for it to adhere to the humidity sensing part 1 and the electrode 3. In this way, in any state, the humidity sensing section 1
And the electrode 3 is free from adhesion of the inorganic solid particles.
Figure 2 shows the relationship between the solid angle of the aperture 6 and the deterioration of the sensor under severe conditions in which seawater was sprayed from right side to the aperture 6 at a wind speed of about 0.55 m/s on the humidity sensor configured as described above. . As shown in the figure, it can be seen that by reducing the solid angle to 1/10 or less, sensor deterioration due to salt in windy conditions can be significantly reduced. From the viewpoint of salt removal, it can be said that the smaller the area of this opening, the more effective it is, but on the other hand, when considering the responsiveness of the humidity sensor to changes in the environment, an opening area of a certain value or more is required. In practical terms, considering the response time of a humidity sensor to be about 10 seconds,
The aperture size is 1/1000 steradian.

On the other hand, water vapor in the atmosphere is adsorbed to the humidity sensing part 1 through the opening 6 due to 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, inorganic solid particles in the atmosphere are prevented from adhering to the
And the humidity of the atmosphere can be detected 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 5, and lead wire 7 are the same as in the above embodiment, they are given the same reference numerals and detailed explanations will be omitted. The difference from the above embodiment is as shown in Fig. 3 a and b.
It is located in the opening 6a as shown in FIG. That is, the opening 6a is
Instead, it is provided in the holding part 5.

Regarding the humidity sensor configured as above,
The operation will be explained below.

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 this, the humidity sensing part 1 and the electrode 3
The device is completely covered with a casing with no openings, so it is less affected by the surrounding airflow conditions and can avoid the adhesion of inorganic solid particles. Furthermore, if this opening 6 is also used as a through hole for the lead wire 7, it will be advantageous in manufacturing the sensor.

As described above, according to this embodiment, by providing the opening 6a in the holding portion 5, 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 such that the solid angle of the opening is 1/10. If limited to the range of ~1/1000, the fourth
It may be provided as shown in FIG. That is, the fourth
In Figure a, openings 6b are provided in two rows in the vertical direction on one side surface of the housing 4. Figure 4b shows the opening 6b as 1
They are standing in line. In FIG. 4c, the openings 6c are arranged in a cross shape. In FIG. 5, an opening 6d is provided on the top surface of the housing 4.

In addition, if the slit width of the opening 6 in the above embodiment is set to 1 mm or less, the housing 4 can also serve as an explosion-proof structure as it is, and even if flammable substances are present in the surrounding area during heating cleaning, an explosion will occur. can be avoided from the dangers of

Effects of the Invention As described above, the present invention accommodates a moisture sensitive part and an electrode in a housing, and provides an opening with a solid angle of about 1/10 to 1/1000 in the housing or holding part. It is possible to prevent deterioration due to the adhesion of inorganic solid particles such as salt particles and dust without significantly impairing its own responsiveness. Furthermore, by reducing the opening to about 1 m/m or less, an explosion-proof structure is imparted to the casing, preventing fires and explosions during heated cleaning, and ensuring safety in use.

[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. 1b is a cross-sectional view of FIG. 1a, and FIG. 2 is a humidity sensor of FIG. 1. A graph showing the relationship between the solid angle of the aperture and element deterioration when seawater is sprayed on the surface of the room, FIG. b is the bottom view of Fig. 3a, Fig. 4
Figures a, b, c, and Figure 5 are side views and cross-sectional views of main parts cut away of examples of changes in the shape, number, arrangement, and installation position of the openings in Figure 1, and Figures 6 a, b are conventional heating FIG. 2 is a partially cutaway vertical cross-sectional view and a cross-sectional view showing the configuration of a cleaning type humidity sensor. 1... Moisture sensing part, 2... Heater, 3... Electrode, 4
...Housing, 5...Holding section, 6...Opening.

Claims (1)

[Claims] 1. A humidity sensing section having an electrode and a heating section of the humidity sensing section;
The holding part of the humidity sensing part and the heating part is combined with the holding part, and the housing includes the humidity sensing part and the heating part, and an opening connecting the inside and outside of the housing is formed in one direction of the housing. The humidity sensor is provided on a side surface of the humidity sensor, and the opening is formed in a size such that a solid angle from the humidity sensing section or the center of the casing does not exceed 1/10 steradian. 2. The humidity sensor according to claim 1, wherein the width of the opening is 1 mm or less. 3. The humidity sensor according to claim 1, wherein the opening is a slit. 4. The humidity sensor according to claim 1, wherein the opening is composed of a plurality of through holes, and the solid angle thereof connects the outline of the plurality of through holes. 5 Claim 1 in which the opening is provided at the top of the casing
Humidity sensor as described in section. 6. The humidity sensor according to claim 1, wherein the holding portion is provided with an opening.