JPH0412451Y2 - - Google Patents

Description

[Detailed description of the invention] "Industrial application field" This invention detects the moisture in the soil and sends an electric signal to automatically supply water when the cultivation soil becomes dry, for example in an automatic water supply facility for plant cultivation. Regarding a soil moisture sensor that generates

"Conventional technology" Conventional soil moisture sensors are, for example,
As disclosed in Publication No. 23933 and Publication No. 55-25147, a pair of electrodes are buried in the soil facing each other,
Changes in electrical resistance due to moisture between the electrodes were detected using a detection circuit using electronic components.

``Problems to be solved by the invention'' However, this method not only requires a complicated electronic circuit, but also requires auxiliary circuits such as a sensitivity adjustment circuit, making it expensive. In addition, since the moisture detection range in the depth direction is limited to a specific depth where the electrode is installed, it is not possible to detect the total moisture in the cultivation area. The amount of water supplied was greatly affected by the installation depth, making it extremely inconvenient to use. Therefore, for example, when cultivating in a planter, even if the entire cultivation soil in the planter has sufficient moisture, if the small part where the electrode is installed dries out, water will be supplied based on the sense of dryness in that local area. However, there was an overall excess of water, which caused the worst root rot for the plants.

Therefore, the purpose of this invention is to be able to generate an electric signal for moisture sensing with a simple mechanical configuration without requiring a complicated electronic circuit, and to easily sense the total moisture in the cultivation area. To provide a soil moisture sensor that can perform appropriate automatic water supply control without causing excessive water supply.

``Means for Solving the Problems'' The soil moisture sensor according to the present invention will be explained with reference to the embodiment shown in Fig. 1. In order to absorb water by piercing it into the soil, 2
The lower end of the case 2 is tapered, and a plurality of vertically elongated water guide grooves 5 are provided at intervals in the circumferential direction on the peripheral wall of the case 2. And the case 2
A cellulose sponge 20 that expands according to the amount of water absorbed is housed inside the case 2, and the upper opening of the case 2 is closed with an electrically insulating cap 10. An adjusting screw rod 17 for sensing adjustment is screwed through the cap 10, and a fixed electrode plate 27 is provided on the adjusting screw rod 17 within the case 2. On the other hand, the movable electrode 23, which together with the fixed electrode plate 27 constitutes a switch 28, is provided at the upper end of the sponge 20 so as to come into contact with the fixed electrode plate 27 when lowered to a predetermined height.

``Operation'' This soil moisture sensor is used by sticking it into the soil. When water in the soil enters the case 2 through the water guide groove 5 and the cellulose sponge 20 absorbs water, it expands and stretches within the case 2 according to the amount of water absorbed. The water guide grooves 5 are vertically long and narrow, and are provided in plurality at intervals in the circumferential direction, so that water in the soil around the case 2 can be removed in all directions.
Can absorb water over a length range. When the soil dries and the amount of water absorbed in the sponge 20 decreases, the sponge 20 contracts and the movable electrode plate 23 descends to a certain height, the movable electrode plate 23 contacts the fixed electrode plate 27 and the switch 28 is activated. Turns on. The height at which the switch is turned on can be arbitrarily set by adjusting the height of the fixed electrode plate 27 with the adjusting screw rod 17. Therefore, it is easy to adjust how much the amount of water absorption of the sponge 20 should decrease before generating an electric signal.

"Embodiment" An embodiment of the present invention will be described below in detail based on the drawings.

Figures 1 to 3 show an example of a soil moisture sensor of the present invention. This soil moisture sensor 1 has a single-piece structure in which main components are housed in a vertically elongated cylindrical case 2 made of an electrically insulating material. The case 2 has an open upper end, a conical tip cone 3 at the lower end, and a peripheral wall 4 above the tip cone 3.
A large number of vertically elongated water guide grooves 5 are formed as a water guide part, and a male thread 6 is cut into the upper end of the peripheral wall 4. A convex portion 8 having a shaft mounting hole 7 is formed on the upper end surface of the tip cone 3 .

The upper opening of the case 2 is closed by a cap 10, also made of electrically insulating material, which has a female thread 9 that engages with the male thread 6 thereof. The cap 10 has a wire outlet 11 protruding from its upper surface, a threaded rod mounting hole 12 formed in its upper wall, and a connecting terminal 13 and a nut 1 formed under the threaded rod mounting hole 12.
4 is buried, and another connection terminal 15 is buried in the center of the bottom surface. An adjusting screw rod 17 having a knob 16 at the upper end is passed through the screw rod attachment hole 12, and a male threaded portion 17a of the adjusting screw rod 17 is screwed into the nut 14 and thrust into the case 2.
Also, the lower end of the conductive shaft 18 is connected to the shaft mounting hole 7 of the tip cone 3, and the upper end is connected to the connecting terminal 1 in the center of the cap 10.
5, the conductive shaft 18 is supported vertically along the center line of the case 2. Electric wires 19 connected to both connection terminals 13 and 15 are drawn out through the wire outlet 11.

A cylindrical natural cellulose sponge 20 is inserted into the case 2. This sponge 20
has a concave portion 21 on its lower surface that fits into the convex portion 8 of the tip cone 3, and a shaft through hole 22 through which the conductive shaft 18 passes is bored along the center line.

A conductive movable electrode plate 2 is placed on the upper end of the sponge 20.
3 is glued. This movable electrode plate 23 has a hole 24 through which the conductive shaft 18 passes, and a long protrusion 25 and a short protrusion 26 that pinch the conductive shaft 18 with spring force. The upper end of the long protrusion 25 is a hook-shaped contact portion 25a that comes into contact with a crescent-shaped conductive fixed electrode plate 27 screwed onto the threaded portion 17a of the adjustment screw rod 17, and is fixed to the movable electrode plate 23. A switch 28 is configured in cooperation with the electrode plate 27.

FIG. 4 shows an example of an automatic water supply system using this soil moisture sensor 1. In this example, two soil moisture sensors 1 are used, one of which is inserted into the cultivation soil 30 of the planter 29 and the other is inserted into the cultivation soil 32 of the pot 31.
is connected to an electromagnetic valve 34 in the middle of the water supply pipe 33 via an electric wire 19, and the electrical connection relationship is shown in FIG. The planter 29 is irrigated by a watering pipe 36 having a large number of watering holes 35, and the pot 31 is irrigated by a shower 37. The water sprinkler pipe 36 and the shower 37 are each connected to the water supply pipe 33 via an electromagnetic valve 34, and are supplied with water or liquid fertilizer in the water storage tank 38 by a reversible electromagnetic pump 39 in the water storage tank 38. A battery 40 is also housed in the water storage tank 38, and the electromagnetic valve 34 and the electromagnetic pump 39 operate using this as a power source. The switches 28 of the two moisture sensors 1 are connected to the electromagnetic pump 3 via an OR circuit 41.
9, and when the switch 28 of any one moisture sensor 1 is turned on, the electromagnetic pump 3
9 is activated.

In such usage conditions, when the cultivation soil 30 in the planter 29 or the cultivation soil 32 in the pot 31 dries, the sponge 20 of the moisture sensor 1 stuck therein contracts, and as a result, the movable electrode plate 2
3 slides down along the conductive shaft 18, its contact portion 25a contacts the fixed electrode plate 27 as shown by the solid line in FIG. 1, and the switch 28 is turned on.
When the electromagnetic valve 34 connected thereto is opened, the electromagnetic pump 39 is operated, and the dry planter 29 or pot 31 is irrigated with water or liquid fertilizer in the water storage tank 38. When the sponge 20 absorbs water due to this irrigation, it expands (expands) and moves the movable electrode plate 23 to the conductive shaft 18 as shown by the broken line in FIG.
The contact portion 25a is moved away from the fixed electrode plate 27, the switch 28 is turned off, the electromagnetic valve 34 is closed, the electromagnetic pump 39 is stopped, and irrigation is completed. By pinching the knob 16 and turning the adjustment screw rod 17 to move the position of the fixed electrode plate 27 up and down, the on position of the switch 28 in response to the contraction of the sponge 20 can be adjusted up and down. Irrigation can be done at any time depending on the degree of dryness. Therefore,
Appropriate watering can be performed depending on the plants being cultivated.

The present invention uses a sponge as a moisture sensing member, and its focus is on turning the switch on and off by the contraction and expansion of the sponge as its water absorption changes. According to this article, in the case of a cylindrical natural cellulose sponge like the one in the example, if it is 40 mm long and 8 mm in diameter when dry, when it absorbs enough water, it will expand by 48 mm, or 8 mm, and weigh 4 g. was able to lift it.

``Effect of the invention'' As detailed above, the soil moisture sensor according to the invention has a vertically cylindrical case with a tapered lower end that is stuck into the soil, and a water guide groove provided in the case allows water to flow into the soil. Water is introduced into the cellulose sponge, causing it to absorb water and expand, and when the sponge loses its water absorption and contracts, the movable electrode plate provided at its upper end descends to a certain height and comes into contact with the fixed electrode plate.
It is designed to be a switch.

Therefore, an electrical signal for moisture sensing can be generated with a simple mechanical configuration without requiring a complicated electronic circuit.

In addition, a plurality of vertically elongated water guide grooves are provided at intervals in the circumferential direction of the case, and moisture in the soil around the case is absorbed in all directions and over the length of the water guide grooves. Since the cellulose sponge expands according to the amount of water it absorbs, it is easy to sense the total amount of moisture in the cultivation area, and automatic water supply control can be performed to prevent excess moisture.

Furthermore, by adjusting the height of the fixed electrode plate with the adjustment screw lever, it is possible to easily adjust how much the amount of water supplied to the sponge should decrease before generating an electric signal.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal cross-sectional view thereof, FIG. 2 is a cross-sectional view seen above the - line in FIG. 1, and FIG. 3 is a cross-sectional view similarly seen below. A top view, Figure 4 is a cross-sectional view of the entire structure showing the state of use, and Figure 5 is
The figure is an electrical circuit diagram. 1...Soil moisture sensor, 2...Case, 3...
Tip cone, 5... Water guide groove, 17... Adjustment screw rod, 20... Sponge, 23... Movable electrode plate, 2
7...Fixed electrode plate, 28...Switch.

Claims (1)

[Scope of utility model registration request] In order to penetrate the soil and absorb water, the lower end of the vertically cylindrical case 2 is tapered, and a plurality of vertically long and narrow water guide grooves 5 are provided on the peripheral wall of the case 2 at intervals in the circumferential direction. A cellulose sponge 20 that expands according to the amount of water absorbed is housed in the case 2, and the upper opening of the case 2 is closed with an electrically insulating cap 10, and an adjustment screw rod 17 for sensing adjustment is attached to this cap 10. The fixed electrode plate 27 is screwed through the adjusting screw rod 17 in the case 2.
is provided, and on the other hand, the switch 2 is connected to the fixed electrode plate 27.
A soil moisture sensor characterized in that a movable electrode 23 forming part 8 is provided at the upper end of a sponge 20 so as to come into contact with a fixed electrode plate 27 when lowered to a predetermined height.