JPH0534556U - Humidity calibrator - Google Patents

Abstract

(57) [Summary] [Purpose] In a humidity calibrator for a humidity sensor, quickly achieve a desired constant humidity. [Constitution] A permeable cylinder 1 having a large number of fine pores having an average pore diameter of 20 μm or less and permeable to water vapor and impermeable to liquid is molded from porous polyethylene synthetic resin. The O-ring 3 is superposed on the lower end surface of the transparent cylinder 1 and is housed coaxially in the cup-shaped holding cylinder 7. Packing 5 stacked on the upper end surface of the transparent cylinder 1.
The annular inner lid 11 is screwed into the holding cylinder body 7 by pressing to form a sealed chamber 13 between the outer periphery of the side wall of the transmission cylinder body 1 and the inner wall of the holding cylinder body 7. The saturated salt solution 15 is enclosed in the enclosure chamber 13. The stopper 21b of the outer lid 21 is press-fitted into the hollow portion 19 penetrating the inner lid 11 to form the humidity space 23 in the transmission cylinder 1.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a humidity calibrator, and more particularly to improvement of a simple humidity calibrator used for calibrating a humidity sensor that measures humidity.

[0002]

[Prior Art]

 Humidity sensors sometimes need to be calibrated by a humidity calibrator from the viewpoint of always ensuring accurate humidity measurement, and a humidity calibrator using a saturated salt solution is provided because a constant humidity can be easily obtained. As a humidity calibrator of this type, as described in, for example, Japanese Patent Application Laid-Open No. 2-165043, a semi-permeable membrane that stores a saturated salt solution in a cup-shaped cartridge and allows water vapor to pass therethrough while not allowing liquid to pass therethrough. There is a configuration in which the upper opening of the cartridge is closed with, the lower part of the cylindrical base part is fitted to the outside of the cartridge, the plug serving as a cap is fitted on the upper part, and a sealed space is formed in the base part. In the humidity calibrator with this configuration, water vapor spontaneously evaporated from the saturated salt solution in the cartridge diffuses into the sealed space in the base through the semipermeable membrane, and after the sealed space reaches a certain humidity, the plug is removed. Calibration can be performed by removing the sensor and inserting the sensor part of the humidity sensor into the base part and inserting it into the sealed space.

[0003]

[Problems to be solved by the device]

 However, in the humidity calibrator having the above-mentioned configuration, the desired constant humidity is obtained exclusively by the natural evaporation of water vapor from the saturated salt solution in the cartridge, and the water vapor of the tubular shape passes through the opening of the cup-shaped cartridge. Since it diffuses into the base from below, it takes a long time to evaporate and condense water vapor, and it takes a long time to reach a certain humidity. In addition, since the cylindrical base is exposed to the outside air, rapid changes in ambient temperature immediately affect the cartridge and saturated salt solution, and relative humidity changes greatly with changes in ambient temperature. There is a problem that it takes several hours for the water vapor to evaporate and return to the original constant humidity when dew condensation occurs inside the part.

Although there is a proposal to incorporate a stirring device such as a fan in the base part, the humidity calibrator becomes large and small and not suitable for carrying. The present invention has been made in order to solve such a conventional drawback, and an object thereof is to provide a simple humidity calibrator having a structure in which a desired constant humidity can be quickly obtained. Another object of the present invention is to provide a humidity calibrator that suppresses a change in internal humidity with respect to a change in ambient temperature.

[0005]

[Means for Solving the Problems]

 In order to solve such a problem, the present invention is made of a porous synthetic resin having a large number of pores having an average pore diameter of 20 μm or less, which is permeable to water vapor and impermeable to liquid, and is formed into a cylindrical shape. Is arranged coaxially on the outer circumference of the transparent cylinder so that a sealed chamber is formed between the transparent cylinder whose end face is openable and which is internally sealed, and at least the outer circumference of the side wall of the transparent cylinder. The holding cylinder body for holding the transmission cylinder body and the saturated salt solution sealed in the sealing chamber are configured. Further, in the present invention, it is preferable to cover the outer circumference of the holding cylinder with a heat insulating material.

[0006]

[Action]

 In the present invention equipped with such means, the saturated salt solution enclosed in the outer circumference of the side wall of the cylindrical permeation cylinder becomes a column shape and contacts the outer circumference of the side wall of the permeation cylinder, and the permeation surface area of water vapor is That is, the evaporation area becomes large, and the inside of the transparent cylinder quickly reaches a constant humidity. Further, in the configuration in which the outer circumference of the holding cylinder is covered with the heat insulating material, the change in ambient temperature is unlikely to affect the holding cylinder, the saturated salt solution or the permeation cylinder.

[0007]

【Example】

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the permeation cylinder 1 has a large number of fine pores with an average pore diameter of 20 μm or less, and has a cylindrical shape with a density of 0.49 to 0.575 g / cm ³ , and is composed of a saturated salt solution 15 described later. It is formed by molding an organic polymer porous sintered material that is permeable to water vapor and impermeable to liquid, for example, porous polyethylene synthetic resin into a cylindrical shape. Both upper and lower end surfaces of the transparent cylinder 1 are machined smoothly, and a vertically-placed lower end surface is in contact with a Viton O-ring 3 having the same diameter, and the upper end surface is made the same diameter and is made of a silicon rubber ring. The packing 5 abuts and is coaxially housed in the holding cylinder 7.

The holding cylinder 7 is formed of, for example, a polyacetal synthetic resin into a cup shape, the inner diameter thereof is larger than the outer diameter of the transmission cylinder 1, and a small-diameter concave portion 9 is formed in the center of the inner bottom portion thereof. The transparent cylinder 1 is fitted with the O-ring 3 facing downward to support the transparent cylinder 1. An annular inner lid 11 is screwed into the holding cylinder 7 so as to push the ring-shaped packing 5. The inner lid 11 includes a large-diameter portion 11a having a diameter larger than the outer diameter of the holding cylinder 7, a small-diameter portion 11b having a smaller diameter than the large-diameter portion 11a, and an annular convex portion 11c protruding from the tip surface of the small-diameter portion 11b. And the threaded groove (not shown) formed on the outer circumference of the annular projection 11c is screwed into the threaded groove 7a formed between the upper inner circumference of the holding cylinder 7 to allow the annular projection 11c to pass through. While being fitted between the outer periphery of the upper part of the above and the inner periphery of the upper part of the holding cylinder 7, the packing 5 is pressed by the tip end surface of the small diameter part 11b inside the annular convex part 11c.

Therefore, the ring-shaped packing 5, the transparent cylinder 1 and the O-ring 3 are pressed by the inner lid 11 toward the small-diameter concave portion 9 of the holding cylinder 7, and the outer circumference of the side wall of the transparent cylinder 1 and the inner wall of the holding cylinder 7 are pressed. A sealed enclosure 13 is formed between them. As described above, since both end surfaces of the transparent cylinder 1 are processed smoothly, the close contact with the ring-shaped packing 5 and the O-ring 3 is secured. If a sealing material is applied to the thread groove on the outer periphery of the annular convex portion 11c or the thread groove 7a of the holding cylinder 7, the airtightness of the enclosure chamber 13 is further enhanced. A known saturated salt solution 15 is enclosed in the enclosure chamber 13, and the saturated salt solution 15 is in contact with the outer periphery of the side wall of the permeation cylinder 1. Reference numeral 17 is a salt crystal mixed in the saturated salt solution 15.

The outer lid 21 has a disk-shaped flange 21 a and a stopper 21 b protruding from the central portion of one end surface of the outer lid 21, and the stopper 21 b is press-fitted into a hollow portion 19 penetrating the inner lid 11 to form a transparent cylinder. The inner space 1 is a sealed humidity space 23. Reference numeral 25 in FIG. 1 is a thin vent hole that allows gas in the humidity space 23 to escape to the outside when a humidity sensor (not shown in FIG. 1) is inserted into the humidity space 23 of the transmission cylinder 1. The mere presence of the pores 25 does not change the humidity. In such a humidity calibrator, the saturated salt solution 15 is widely in contact with the permeation cylinder 1 by interposing it in a cylindrical shape around the side wall of the permeation cylinder 1, so that the evaporation area of water vapor from the saturated salt solution 15 is large. Is increased, the diffusion amount of water vapor becomes larger and the diffusion speed becomes faster than in the conventional example, and the humidity space 23 in the transmission cylinder 1 is likely to quickly reach a constant humidity.

According to the calculation made by the present inventor, comparing the conventional steam generator area with the conventional steam calibrator with the same dimensions, the present steam calibrator has about 6 times the conventional steam calibrator. It was found to have a steam generation area of. Further, an experiment was carried out by forming a transparent cylinder 1 having a thickness of 3 mm, an inner diameter of 17.5 mm and a length of 25 mm from a porous polyethylene synthetic resin, and changing the average pore diameter of fine pores to 100 μm, 50 μm, 20 μm and 10 μm. As a result, in the permeation cylinder 1 having an average pore diameter of 100 μm, the saturated salt solution 15 oozes out into the humidity space 23 in the permeation cylinder 1 even in a stationary state. However, in the permeation cylinder 1 having an average pore diameter of 50 μm, only water vapor is stationary. Although it permeates into the humidity space 23, when some impact is applied, the saturated salt solution 15 oozes out into the humidity space 23.

Further, in the transmission cylinder 1 having an average pore diameter of 20 μm and 10 μm, the saturated salt solution 15 did not ooze out into the humidity space 23 even in a stationary state or when a shock was applied. Further, in the humidity calibrator of the present invention, the inner lid 11 is removed, and the humidity sensor A is inserted into the humidity space 23 of 75% RH as shown in FIG. As a result, the response time of 63.2% and 95.0% with respect to 75% RH was measured for the transmission cylinder 1 having pores with average pore diameters of 50 μm, 20 μm and 10 μm. Got Reference numeral a in FIG. 5 indicates a sensor portion of the humidity sensor A.

As shown in FIG. 2, a 63.2% response time is 72 sec and a 95.0% response time is 527 sec for an average pore size of 50 μm, and a 63.2% response time is 131 sec for an average pore size of 20 μm as shown in FIG. , 95.0% response time is 642 sec, and for an average pore size of 10 μm, 63.2% response time is 180 sec and 95.0% response time is 834 sec as shown in FIG. 0% Response time is slow. However, if the thickness of the transmission cylinder 1 is made as thin as possible, the response time becomes faster, and the humidity calibrator does not require an extremely fast response. Since it is necessary to prevent the saturated salt solution 15 from bleeding out into the transmission cylinder 1 no matter what impact is applied, in the humidity calibrator of the present invention, many holes of the transmission cylinder 1 have an average hole diameter of 20 μm or less. It is possible to achieve the object of the present invention by carrying out. The transparent cylinder 1 can be implemented with a thickness of about 1.0 to 5.0 mm, depending on its material.

Further, the permeable cylinder 1 is not limited to the above-mentioned porous polyethylene synthetic resin, but may be a porous polypropylene synthetic resin, but the porous metal sintered material has a large heat capacity and changes in temperature. It is not preferable because it is difficult to cope with the above condition and the relative humidity shifts. Moreover, the porous metal sintered material may cause corrosion depending on the type of the saturated salt 17, which is also not preferable from this point of view. Further, although the ceramic material also has porosity, it is not suitable for the permeable cylinder 1 because it does not have good heat followability like an organic polymer porous sintered material. By the way, the hollow portion 19 of the inner lid 11 in the calibrator for a hygrometer according to the present invention has an inner diameter such that the humidity sensor A is just fitted as shown in FIG. 5 from the viewpoint of ensuring accurate calibration and has a gap. It is better not to cause, and the inner lid 11 having the hollow portion 19 corresponding to the outer diameter and shape of the humidity sensor A may be replaced and fitted. Needless to say, the outer lid 21 is paired with the inner lid 11.

FIG. 6 is a longitudinal sectional view showing another embodiment of the humidity calibrator of the present invention. In this structure, in the humidity calibrator of FIG. 1, the outer periphery of the holding cylinder 7 is covered with a cup-shaped outer cylinder 29 via a heat insulating layer 27 made of, for example, polyethylene foam, and is formed on the upper part of the inner wall of the outer cylinder 29. The outer circumference of the large diameter portion 11a of the inner lid 11 is screwed into the screw groove 29a, and the heat insulating layer 27 is interposed between the outer tubular body 29 and the holding tubular body 7. In the humidity calibrator having such a configuration, the change in ambient temperature is absorbed by the heat insulating layer 27, and the temperature change of the holding cylinder 7, the saturated salt solution 15, and the permeation cylinder 1 changes to “0” or slowly, so that the saturation is saturated. The temperature balance between the salt solution 15 and the water vapor is kept good, and the humidity change in the humidity space 23 can be suppressed to be small with respect to the change of the ambient temperature.

With respect to the configuration of FIG. 6 in which the outer periphery of the humidity calibrator of FIG. 1 is covered with the heat insulating layer 27 of about 10 mm and the configuration of FIG. 6 and the configuration of FIG. The ambient temperature was raised and the changes in humidity 75% RH and 33% RH in the humidity space 23 of the transmission cylinder 1 were measured. As a result, as shown in FIGS. 7 and 9, in the configuration of FIG. 1, the humidity 75% RH in the humidity space 23 changes from 74.5% RH to 79.5% RH, and the humidity change of about 5%. Therefore, the humidity 33% RH changes from 33% RH to 35% RH and the humidity change of about 2% is recorded. Regarding the temperature change of 5 ° C, the humidity change of 5 to 10% of the humidity fixed point can be estimated. ..

On the contrary, as shown in FIGS. 8 and 10, in the configuration of FIG. 6, the humidity change of 2% or less can be suppressed even in the humidity of 75% RH and 33% RH in the humidity space 23. Moreover, the structure of FIG. 6 also has good durability, for example, the saturated salt solution 15 did not leak even if dropped from the height of about 1 m onto the corrugated ball 100 times, and the number of times of 200 times in 80 seconds. Similarly, the saturated salt solution 15 did not leak even if it was hit with the knee. Further, even when shaken 400 times with an amplitude of 20 cm and 4 Hz, the saturated salt solution 15 did not leak.

In each of the above-described embodiments, the structure in which the saturated salt solution 15 is contacted with the outer periphery of the side wall of the cylindrical transmission cylinder 1 has been described, but the present invention is not limited to this, and the transmission cylinder 1 is formed into a cup shape. A configuration is also possible in which one end is closed so as not to be opened by molding, the saturated salt solution 15 is enclosed in the outer periphery of the side wall and the bottom wall, and water vapor is permeated from the outer periphery of the side wall and the bottom wall. The point is that one or both end faces of the transparent cylinder 1 whose inner space is sealed so that the end face side can be opened is used, and the sealing chamber 13 is formed at least between the transparent cylinder 1 and the outer periphery of the side wall of the transparent cylinder 1. Saturated salt solution 15 may be enclosed in 13.

[0019]

[Effect of the device]

 As described above, according to the present invention, the transmission cylinder is molded from a synthetic resin having a large number of holes having an average pore diameter of 20 μm or less, and the end face is openable, and the transmission cylinder is coaxially formed in the holding cylinder. Since the saturated salt solution was supported between the outer circumference of the side wall of the permeation cylinder and the inside of the holding cylinder, the saturated salt solution came into contact with the outer circumference of the wide side wall of the permeation cylinder, and the evaporation area of water vapor was greatly expanded. , Water vapor permeates quickly and the humidity space in the transparent cylinder quickly becomes constant humidity. Also, in the configuration in which the outer circumference of the holding cylinder is covered with a heat insulating material, changes in the ambient temperature are less likely to affect the holding cylinder, the saturated salt solution or the permeation cylinder, and the humidity of the internal space and the humidity of the space against changes in the ambient temperature. Changes can be kept small.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a humidity calibrator according to the present invention.

FIG. 2 is a characteristic diagram showing a saturated humidity response of the humidity calibrator of FIG.

FIG. 3 is a characteristic diagram showing a saturated humidity response of the humidity calibrator of FIG.

FIG. 4 is a characteristic diagram showing a saturated humidity response of the humidity calibrator of FIG.

5 is a vertical cross-sectional view showing an example of use of the humidity calibrator of FIG.

FIG. 6 is a vertical sectional view showing another embodiment of the humidity calibrator according to the present invention.

7 is a characteristic diagram showing changes in humidity with respect to changes in ambient temperature in the humidity calibrator of FIG.

8 is a characteristic diagram showing changes in humidity with respect to changes in ambient temperature in the humidity calibrator of FIG.

9 is a characteristic diagram showing changes in humidity with respect to changes in ambient temperature in the humidity calibrator of FIG.

10 is a characteristic diagram showing changes in humidity with respect to changes in ambient temperature in the humidity calibrator of FIG.

[Explanation of symbols]

 1 Transmission Cylindrical Body 3 O-ring 5 Packing 7 Holding Cylindrical Body 9 Small Diameter Recess 11 Inner Lid 11a Large Diameter 11b Small Diameter 11c Annular Convex 13 Enclosing Chamber 15 Saturated Salt Solution 17 Salt Crystal 21 Outer Lid 21a Flange 21b Stopper 23 Humidity Space 25 Vent hole 27 Insulation layer 29 Outer cylinder A Humidity sensor a Sensor part

Claims (2)

[Scope of utility model registration request] 1. A cylindrical mold made of a porous synthetic resin having a large number of pores having an average pore diameter of 20 μm or less, which is permeable to water vapor and impermeable to liquid, and at least one end face side of which is openable. Holding cylinder which is coaxially arranged on the outer periphery of the transparent cylinder so as to form a sealed chamber between the transparent cylinder sealed and the outer periphery of the side wall of the transparent cylinder. A humidity calibrator, comprising: a body; and a saturated salt solution enclosed in the enclosure chamber. 2. The humidity calibrator according to claim 1, wherein the outer circumference of the holding cylinder is covered with a heat insulating material.