KR830001700B1 - Apparatus of controlling the relative humidity in soil - Google Patents

Abstract

In the apparatus for controlling the relative humidity in soil, a tube for suppling water (108) is established through its body in order to pass the chamber (106) of body, a membrane (104) for transmitting water is established in the open more than uniaxis and the piston (109) for opening or closing the tube is established in the chamber near to the membrane for transmitting water. The expansive material (114) of water, which can expand more than about 25 times of the total volume for dryness in the equilibrium with water at 100% of the relative humidity, is established. The tube is limited or closed when the expansive material expands.

Description

Soil relative humidity detection and control device

1 is a longitudinal sectional view of the valve of the present invention in an uncompressed state.

2 is a longitudinal sectional view of the first degree valve in a compressed state.

3 is a longitudinal sectional view of another example valve.

4 and 5 are longitudinal cross-sectional views of yet another example valve.

The present invention relates generally to a relative humidity sensing-adjustment apparatus for soil for regulating the supply of water to soil around plants in accordance with moisture or moisture in the soil.

In horticulture, it is common to grow seedlings or ornamental trees of trees and agricultural seeds in natural or artificial soils in outdoor or indoor greenhouses or hotbeds. Plants in these containers are required to vary the water supply according to various factors such as plant shape, growth, air flow around the leaves and relative humidity and drainage through the container soil.

Where the water supply is abundant, by spraying enough water from the plants so that water flows on the ground, it can conveniently meet the needs of plants outdoors or in greenhouses and hot springs. However, when the effort to maintain the water supply is increased, this becomes less than ideal. However, if the problem of indoor cleanliness is caused by excess water flow in the room, there is a need to carefully water the plants contained in the containers individually. Such a job is likely to be supplied with excess or insufficient water that is harmful to cumbersome and special plants.

In plants of the field, especially in dry areas where the soil becomes unevenly highly porous and at high temperatures and low air humidity, the amount of water lost by evaporation and gravity exudation from the root system through the soil is lost by evaporation from the leaves of the crop. The water can be far exceeded and can vary greatly depending on the plant. Therefore, a valuable water supply that effectively maintains agriculture is often not met by the traditional or most advanced irrigation techniques.

It is an object of the present invention to provide an apparatus for continuously supplying a water supply required by a plant to each or a plurality of plants continuously.

Another object of the present invention is to provide an inexpensive and compact water supply device that is suitable for both water supply and agricultural irrigation of plants grown at home and that operates reliably for a long time.

Typical high quality soils are porous, somewhat absorbent and have good drainage. Except for many rains or just after watering, plant roots are generally not submerged and are exposed to the soil particles and the humid air surrounding the roots. Water is separated into gaseous and wet soils. The humidity in the gaseous state of the soil is controlled by the so-called metric potential of the water. This is usually expressed in terms of osmotic potential or bar pressure. Pure water has a potential of zero, and less usable water has a negative metric potential.

The following calculation is provided to exclude the osmotic potential for soil moisture.

는. 순수한 물의 물체적(즉, 표준 상태하의 물의 1그램몰 무게의 체적인데, 이것은 18.02ml이며,

는리터당 55.5몰의 물)이고, R은 기체상수(8.314×10^-2리터-바아/물-。K)이며, X_W는 더이상 용액속의 물의 물분률이라고 할때,π is the osmotic potential of the non-dilute solution of the nonvolatile solute S in water, T is the absolute temperature 。K,

Is. The volume of pure water (ie the volume of 1 gram molar weight of water under normal conditions, which is 18.02 ml,

Is 55.5 moles of water per liter), R is the gas constant (8.314 × 10 ^-2 liters-bar / water-。K), and X _W is no longer the fraction of water in the solution,

Where 27 ° C. = 300 ° K, π = −1,383 1 _n W _w bar (one bar is 0.987 atmospheric pressure). If the water concentration of water is C _w and the solute water concentration is C _s ,

바아 [-1_nX_w=-1n(1-X_s)=X_s+1/2 X^s ₂+1/3 X^s ₃+…, 여기서 X_s≪1(즉 C_w≫C_s)에서,

이고 , 따라서 π

25C_s바아인데, 이것은 희석용액에서의 반트호프 법칙이다.therefore,

Bar [-1 _n X _w = -1 _n (1-X _s ) = X _s +1/2 X ^s ₂ +1/3 X ^s ₃ +. , Where X _s ≪1 (that is, C _w ≫C _s ),

, And π

It is a 25C _s bar, which is the Bandthof's law in dilute solutions.

The relative humidity RH of the ideal solution and the air in equilibrium is X _w .

Raoult's law

The osmotic potential of the aqueous solution of a water soluble long chain polymer is far from ideal at high concentrations. The pressure is higher than calculated from the ideal from two sources. The polymer increases the fraction of water and increases the hydrogen bonding of the water, which leads to a decrease in C _w .

Also, when the polymer chain ends are entangled with each other, the momentum transfer in the collision is mainly of the short portion of the undisturbed polymer, resulting in higher concentrations of low molecular weight molecules.

Therefore, the required concentration of the polymer producing a given osmotic potential is somewhat lower than that calculated based on the above assumptions.

Since the crosslinked aqueous gel d is a molecule, its water concentration is very low, and conversely, the water fraction X _w of the water in the gel is invariant regardless of its weight concentration.

If the condition is abnormal, the osmotic pressure of the gel will be zero.

In fact, the state of the crosslinked gels shows osmotic pressure which they can ignore at high values of crosslinking. As crosslinks decrease or increase in between, their osmotic state approaches closer to that of an equivalent solution of long chain polymer.

That is, they act as if the solution consists of some water concentration of the short chain portions, producing a very suitable osmotic potential. (When these gels swell in contact with water, tension occurs along the chain and the number of unobstructed and unrepressed parts decreases, reducing the osmotic potential faster than that calculated for the increased volume of gel).

Chemical binding forces (eg hydrogen bonding), capillary forces, surface absorption and decomposed solutes and osmotic potentials of the hygroscopic material reduce the tendency of the soil to evaporate into the gaseous state. Because of these forces in wet, well-drained soil, also called "filed capacity," (upon planar), the relative humidity is slightly less than 100% and the metric potential is around -0.3 bar. As the soil dries, the weaker bound water in the largest capillary space is consumed first, then the smaller capillary space is consumed, the humidity is stronger and the metric potential becomes more negative.

If the relative humidity of the soil drops to what is called "permanent wilting potential," the plant will die from the lack of water in the soil. The permanent hygroscopic potential drops to -10 and -15 bars corresponding to a relative humidity of about 99%. It changes slightly depending on the shape of the soil and hardly changes depending on the shape of the plant.

For minimum pressure and maximum plant growth, the soil's water should be kept below the metric potential of 0.3 bar, ie the soil should not be submerged and should be above about 6 bar.

Other soils, such as clay, loam, sandy loam and fine sand, have different amounts of water per unit volume at the same metric potential. However, this is a metric potential that determines the usefulness of water for the root system, and at a constant optimal metric potential, soils with very low water content can act as well as good soils. Therefore, a device configured to detect the relative humidity (metric potential) of soil in the root zone and regulate the flow of water to maintain a relatively constant matrix potential through negative feedback is equally applicable to all kinds of plants in all kinds of soils. Will work.

Accordingly, the present invention provides an apparatus for controlling the relative humidity in the soil around the root of the plant to control the moisture content in the soil around the root. The device is called osmotic relative humidity sensing-control valve.

The relative humidity sensing-regulator is a sensing element portion comprising a sealed water volume having a water soluble or water expandable substance that detects the relative humidity of the soil around the roots up to a predetermined value of the material concentration, the sealed water volume. The part is separated from the soil around the root by a semipermeable membrane that is impermeable to the water soluble or water expandable material and permeable to water, and the direction and amount of water passing through the membrane as a result of osmotic transmission depends on the relative humidity of the surroundings, By varying the input acting on the soluble portion of the water supply line or the flow control diaphragm, the flow of water from the isolated water source to the surrounding soil is controlled in another way.

If the device reacts quickly and the water supply is not exceeded (ie there is sufficient hydraulic resistance in the device), the flow is continuous and smooth rather than intermittent. The reaction rate of the device is proportional to the ratio of the outer surface area of the membrane to the volume change required to reduce the water flow. This is also proportional to the water permeability of the semipermeable membrane and the hydrogel.

Semi-permeable membranes prepared for ultrafiltration by reverse osmosis and desalination of sea water have properties very close to those required for this process. They can pass a flow of about 1 microliter of water per cm 2 at a pressure difference of 1 atmosphere and withstand low atmospheric pressure without rupturing.

The disadvantage of using semipermeable membranes filled with relatively high molecular weight solute solutions is that when these devices are operated for more than one year, the seals of the membranes and chambers must be taken to absolutely prevent leakage.

The "filler" preferably comprises a mixed, slightly crosslinked gel, and the leak problem disappears. Virtually semi-rigid meshes of slightly larger holes (eg 0.2 mm) can be used as the "semi-permeable membrane". Of course, the mesh is free to pass water but does not expand significantly through the mesh hole even if the gel expands. As the osmotic flow occurs into the device, the gel expands inward to compress the soluble portion of the water line.

In a preferred embodiment, the osmotic sensing device comprises a chamber surrounding a flexible tube for impermeable water, a water expandable material surrounding the flexible tube and occupying the chamber, and an impermeable adult chamber for the water expandable material. It consists of a semi-permeable water-permeable membrane that forms part of the outer wall.

In another preferred embodiment, the osmotic sensing device comprises a chamber wherein the water impermeable flexible tube forms part of the chamber outer wall, semi-permeable water impermeable to the water expandable material and forming a second shaft portion of the chamber, A membrane, a piston disposed in contact with the flexible tube, a water expandable material occupying a portion of the chamber between the membrane and the piston, and rigid means positioned adjacent to the flexible tube on the opposite side of the piston. .

In another preferred embodiment, the osmotic sensing device comprises a chamber having one side formed with a semi-water impermeable diaphragm, an impermeable membrane that forms a second side of the chamber and is impermeable to the water-expandable material. A piston disposed in contact with the diaphragm, a water-expandable material occupying a portion of the chamber between the membrane and the piston, and rigid means positioned adjacent the diaphragm on the opposite side of the piston.

The osmotic sensing-adjusting device according to the invention comprises a closed container filled with an aqueous solution of solute or expandable gel which acts as a humidity sensor. At least a part of the wall of the container consists of semi-rigid, semi-permeable deposition.

It can be easily buried in the soil between plant roots. Membranes are largely permeable to water and impermeable to solutes (or water-expandable materials). The concentration of the solute is set such that the chemical potential of the water contained in the volume wrapped with the membrane is close to that of air at 99% relative humidity. If the solute has a molecular weight of about 5,000 and a concentration of about 30% by volume, the concentration of water is about 70% and the osmotic potential is about 2.1 bar assuming ideal conditions.

From Raoult's law, the relative humidity of the device and the air in equilibrium is about 99.8%.

If the humidity in the soil increases above about 99.8%, water will osmotically pass through the membrane, and if the membrane is relatively rigid, and therefore the increase in the hermetic volume due to osmotic expansion is small, The hydrostatic pressure increases to nearly 2.1 bar, at which point the pure flow across the membrane stops.

When the pressure in the seal rises, the flow of water through the compressible means of supplying water to the soil is limited and the negative feedback required by the device is provided. When a plant consumes water, the relative humidity around the roots gradually drops below 99.8%. The water then flows back through the membrane from the enclosed volume through the membrane, the pressure in the device drops, the restriction is released, and the flow of water into the soil increases.

Thin walled silicone rubber tubes or thin films are suitable as materials for the compressible walls of the repair in the detector.

The device of the present invention will be described in detail below with reference to the accompanying drawings.

The proper structure of the valve is shown in FIGS. 1, 2, 3, 4 and 5.

In FIG. 1, osmotic sensing means consisting of a flexible tube 8 arranged through a valve 2 and a water permeable membrane 4, a chamber 6, its chamber 6, an end member 10 and 12 and a water-expandable substance 14 occupying the chamber 6 It includes a mother body having a.

The end member 10 also has a passage 20 with an inner wall 16 and an outer wall 18. The passage 20 extends through the protrusions 22 and 24 formed in the walls 16 and 18, respectively. The end member 12 also has an inner wall 26, an outer wall 28 and a passage 30, and the passage 30 extends through the projections 32 and 34 formed in the inner wall 26 and the outer wall 28, respectively. In a preferred embodiment, the membrane 4 and the end members 10 and 12 form the body of the valve 2. A chamber 6 is formed between the end members 10 and 13 of the outer inner walls 16 and 26, and the surrounding water enters or exits through the membrane 4.

The flexible tube 8 or diaphragm is preferably made of silicone rubber, but any compressible material which is inert in water such as polyurethane, PVC or rubber may be used.

Although the body portion is generally made of polypropylene, materials such as polymer acetal, nylon and polyester that are stable to moisture and have adequate strength may be used.

The water soluble or water expandable material 14 is generally a hydrogel, such as a solid gel formed from polyacrylamide, polyvinyl alcohol, or the like. A hydrogel that can expand smoothly to about 25 times the dry volume when in equilibrium with water at 100% humidity is preferred.

When used with such a hydrogel, the semi-permeable membrane 4 in a mesh form is generally composed of the same material as the body portion.

In some cases, stainless steel mesh may be used.

The projections 22 and 32 are connected to both ends of the flexible tube 8 and the projections 34 and 24 are attached to the supply line, namely the inlet 36 and the line extending into the soil, i.e., the outlet 38, respectively.

FIG. 2 shows the valve of FIG. 1 in a compression, ie closed configuration. As shown, the expandable material 14 in chamber 6 expands in the chamber and places sufficient pressure on the flexible tube 8 to fully collapse or compress the water passage formed by the flexible tube in the region between the protrusions 22 and 32. And thereby prevent the flow of water between inlet 36 and outlet 38.

3 shows another preferred embodiment of the present invention.

The valve 102 includes a body portion 103 having an osmotic sensing means consisting of a water-expandable material 114 partially occupying the water permeable membrane 104 and the chamber 106 and a piston 109 in the chamber 106 and having a cylindrical vertical cross section. The piston 109 has a flat upper surface 111 and a conical lower surface 113 that slopes toward the blunt tip 115. The piston 109 is axially moveable to restrict the water passage through the flexible tube 108 by downward motion actuated by the expansion of the expandable material 114 in the chamber 106. The flexible tube 108 is supported by the body portion 103 and passes through the lower portion of the chamber 106. The bottom surface of the flexible tube 108 is supported by a relatively rigid means such as a plate 117 located adjacent to the flexible tube 108 on the opposite side of the piston 109, ie the bottom wall of the body portion 103.

In operation, the expandable material 114 in the chamber 106 expands in the chamber and applies sufficient pressure to the upper surface of the piston 109 to force the tip 115 of the piston 109 to compress or collapse the flexible tube 108 at its point of contact. To prevent the flow of water between inlet 36 and outlet 38.

Conversely, upon upward movement of the piston 109 the water expandable material 114 contracts in the chamber 106 to decompress the flexible tube 108 at the tip 115 and allow water to pass through the tube 108 between the inlet 36 and the outlet 38.

In FIG. 4 showing another embodiment of the present invention, the valve 202 includes a water-permeable membrane 204, a chamber 206, a water expandable material 214 that partially occupies the chamber 206, a flat upper surface 219 and a conical lower surface 219. And a cylindrical body portion 203 consisting of a piston 209 housed in a chamber 206, the piston 209 being configured to restrict the passage through the flexible tube 208 by downward motion actuated by the expansion of the water expandable material 214 in the chamber 206. It is movable in the axial direction. The flexible tube 208, which is supported by the body and the seat of the piston 209, passes through the bottom of the chamber 206. The bottom surface of the flexible tube 208 is supported by relatively rigid means 223 located adjacent to the flexible tube 208 on the opposite side of the piston 209. Relatively rigid means 223 is a screw member which is screwed into the lower portion of body 203 with a conical upper surface 225 inclined towards dull tip 215 adjacent to the lower surface of flexible tube 208.

The operation of valve 202 is similar to that described for valve 102 in the embodiment of FIG. The expandable material 214 in the chamber 206 expands in the chamber and applies sufficient pressure to collapse or compress the flexible tube 208 at the bottom surface 221 of the piston 209 in contact with the blunt tip 215 of the member 223. It is applied to surface 219 to prevent the flow of water between inlet 36 and outlet 38.

Conversely, the upward movement of the piston 209 caused by the contraction of the volume of the expandable material 214 in the chamber 206 eliminates the compression of the flexible tube 208 at the blunt tip 215 and thus the water between the inlet 26 and outlet 38 Will flow through.

Thread grooves on the members 203 and 223 allow the predetermined humidity to be adjusted over a wide range.

Since the ratio of the area of the top of the piston to the area of the conical tip of FIGS. 3 and 4 is large, the examples in the figure are less sensitive to changes in water supply pressure than the examples in FIGS.

In the embodiments of FIGS. 3 and 4, there is less damage to the assembly since there is no internal connection to the water supply.

In FIG. 5 showing another preferred embodiment of the present invention, the valve 301 consists of a cylindrical upper body portion 302 and a lower body portion 303, and a water-expandable material partially occupying the water-permeable membrane 304, the chamber 306. 314, a piston 309 having a flat upper surface 317 and a conical lower surface 319 disposed in the chamber 306, and a circular flexible contacting the lower surface of the piston 309 and sealed between the edges 325 and 327 of the body parts 302 and 303. Diaphragm 308. Fston's conical lower surface 319 is inclined towards a blunt end 315. The lower portion of the body portion 303 has an inlet 336 for the passage of water, the upper surface of which is in the form of a conical groove 312 corresponding to the shape of the conical lower surface of the piston 309.

The outlet 338 for the passage of water is adjacent to the inlet 336 and penetrates the rigid member 303.

In operation, the water-expandable material 314 in the chamber 306 expands in volume and causes the diaphragm 308 surrounding the bottom surface of the piston 309 to axially close the piston 309 such that the gap between the conical groove 312 of the inlet 336 and the inclined end 315 is closed. Sufficient pressure is applied to the upper surface 317 of the piston 309 to prevent the flow of water between the inlet 336 and the outlet 338.

Conversely, upon upward movement of the diaphragm 308 caused by the contraction of the volume of the water expandable material 314 located in the chamber 306, water enters the space 330 through the inlet 336 and is discharged through the outlet 338.

This process, called hygrostatic irrigation, is particularly useful for conserving water in agricultural irrigation in dry areas, as well as for supplying and regulating water to the root systems of individually contained plants.

It also makes it possible to continuously feed the plant optimally in proportion to the water consumed, ie fertilizers dissolved in the proper concentration in the feed water. This process is also suitable for the control of humidity in environments other than soil.

The present invention also detects the relative humidity of the soil in the root area and, through negative feedback, maintains a relatively constant matrix potential for all kinds of plants in all kinds of soil. It also relates to a device called osmotic relative humidity sensing-control valve designed to regulate flow.

Thus, the apparatus described above is intended for opening and closing the body portion, means for attaching the valve body portion to a pressurized water line, means compressible within the water line to open and close the water line, and flexible means for opening and closing the water line. Osmotic relative humidity sensing-control valve composed of osmotic sensing means.

Claims (1)

In an apparatus for osmotic sensing-adjustment of relative humidity in soil, a flexible tube 108 is disposed through its body portion to pass through the chamber 106 of the body portion 103 and the chamber's open position. At least one side of the water-permeable membrane 104 is installed, and adjacent to the water-permeable membrane has a piston 109 for opening and closing the tube, in equilibrium with water at 100% relative humidity. A device for detecting and controlling relative humidity of soil, wherein a water-expandable material (114) that is at least 25 times larger is disposed to limit or close the flexible tube upon expansion of the water-expandable material.

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