CN2585222Y - Switching soil moisture sensor - Google Patents

Abstract

The utility model relates to a switching soil moisture sensor which is composed of a pottery clay head, a sensor body, a U-shaped mercury manometer, a brush-shaped switch, a zero setting pipe and a cover body, wherein, one end of the sensor body is connected with the pottery clay head, and the other end of the sensor body forms an air collection chamber; the cover body is sealed at one end of the air collection chamber of the sensor body; the U-shaped mercury manometer is sealed in the sensor body; an air column is closed off on one arm of a U-shaped tube of the U-shaped mercury manometer, and the top end of the other arm of the U-shaped tube of the U-shaped mercury manometer is sealed with a pressure sensing film; contacts of metal conducting wires are pressed on the other arm of the U-shaped tube of the U-shaped mercury manometer, wherein, one contact positioned below a mercury surface is near to the lower part of the U-shaped tube, and is always conducted with a mercury column, and the conducting wire which is connected with the contact is used as one external-connecting line of the sensor; connection conducting wires of the rest contacts are respectively soldered on soldering sheets of each step of the brush-shaped switch in turn; a movable contact sheet of the brush-shaped switch is connected with the other external-connecting line; the sensor is also provided with the zero setting tube, and an air valve is arranged on a tube mouth of the zero setting tube.

Description

The switching regulator soil moisture sensor

Technical field

The utility model relates to a kind of soil moisture sensor, particularly relates to a kind of switching regulator soil moisture sensor.

Background technology

Except that minority soil such as saliferous clay, in the different soils, the soil water potential value when a certain crop need be irrigated is a basically identical.Therefore, when selecting the moisture transducer of using for automatic irrigation system, preferably can select the moisture transducer that the soil water potential signal is provided for use.Because the soil water potential value when many crops need be supplied water is clear and definite, the sensor of application response soil water potential just can be realized pouring water of science easily.

The switching regulator soil moisture sensor is according to the depressimeter principle, is that the switching regulator electric signal starts the filling machine with the soil water potential conversion of signals.The soil water potential numerical value of depressimeter is converted to electric signal can be realized by pressure-active element.But,, higher with the pressure resistance type soil moisture sensor general cost that it is made because the price of pressure-active element is more expensive.The electric signal that it produced must be through amplifying modulation before entering program controller, and this will further increase the cost of automatic irrigation system.

Summary of the invention

The purpose of this utility model is, a kind of switching regulator soil moisture sensor is provided, it adopts mercury manometr to make the conversion equipment of soil water potential and electric signal, not only cost of manufacture is low, and owing to adopt the switching regulator electric signal, can make the circuit reduction of automatic irrigation system, reduce the cost of total system.

Above-mentioned purpose of the present utility model is achieved in that a kind of switching regulator soil moisture sensor, sensor body is a tubular body, one end of sensor body is connected with pot clay end, the other end of sensor body is fixed with lid, its key is, the inside of sensor body is packaged with the U-shaped mercury manometr, air column is being sealed on the U-shaped pipe one arm top of U-shaped mercury manometr, the pressure-sensitive film in another arm top sealing-in, and the position that the pressure-sensitive film in close sealing-in at this arm top is connected with the zeroing pipe, the inside of this zeroing pipe autobiography sensor body is protruding via lid, on this outwardly directed mouth of pipe, be combined with air-stopping valve, the U-shaped pipe is being equipped with on pressure-sensitive film one arm, be provided with at least two plain conductor contacts, 1 plain conductor contact wherein is below the mercury face, bottom near the U-shaped pipe, it is in conducting state with mercury slug all the time, the lead that joins with it is directly drawn outside sensor body, an external connection as sensor, and the connection lead of remaining plain conductor contact passes sensor body respectively, be welded in proper order on each grade weld tabs of gauge tap, the movable contact spring of gauge tap and another external connection join.

Switching regulator soil moisture sensor described in the utility model, wherein this lid is a rubber stopper.

Switching regulator soil moisture sensor described in the utility model, wherein this air-stopping valve is connected by the mouth of pipe of soft leather hose with described zeroing pipe.

Switching regulator soil moisture sensor described in the utility model, wherein the number of this plain conductor contact is 12, and this gauge tap is a laminated brush switch.

Below, in conjunction with specific embodiments and accompanying drawing, the utility model is described in further detail.

Description of drawings

Fig. 1 is a switching regulator soil moisture sensor structural representation;

Fig. 2 is a U-shaped mercury manometr negative pressure state synoptic diagram.

Embodiment

With reference to Fig. 1, it is a switching regulator soil moisture sensor structural representation, and this sensor is made up of pot clay end 1, sensor body 2, U-shaped mercury manometr 3, laminated brush switch 4, zeroing pipe 5 and lid 6.In the present embodiment, sensor body 2 is a tubular plastic connecting pipe, and an end of sensor body 2 is connected with pot clay end 1 and the other end formation collection chamber 21 of sensor body 2, and lid 6 is packaged in collection chamber 21 1 ends of sensor body 2.

As can be seen from Figure 1, U-shaped mercury manometr 3 is packaged in the inside of sensor body 2, air column 32 is being sealed on U-shaped pipe one arm 31 tops of this U-shaped mercury manometr 3, pressure-sensitive film 34 in another arm 33 top sealing-ins, on the arm 33 by plain conductor contact 35a is arranged, 35b, 1 plain conductor contact 35a wherein is below the mercury face, bottom near the U-shaped pipe, no matter which kind of negative pressure this U-shaped mercury manometr 3 is in, it is in conducting state with mercury slug all the time, the lead A that joins with it directly draws outside sensor body 2, an external connection as sensor, and the connection lead of remaining plain conductor contact 35b passes sensor body 2 respectively, is welded in proper order on each grade weld tabs of laminated brush switch 4, and the movable contact spring of laminated brush switch 4 and another external connection B join.

From Fig. 1, it can also be seen that, the position that arm 33 tops of the U-shaped pipe of U-shaped mercury manometr 3 pressure-sensitive film 34 near sealing-in is connected with zeroing pipe 5, the inside of these zeroing pipe 5 autobiography sensor bodies 2 is protruding via lid 6, is combined with air-stopping valve 7 on this outwardly directed mouth of pipe.

After water-filled sensor was imbedded in the soil, soil matrix suction acted on the inside of sensor body 2 via moisture film in pot clay end 1 hole, and sensor body 2 inner small amount of moisture flow into soil through pot clay end 1, promptly produce negative pressure in the sensor body 2.Negative pressure makes U-shaped mercury manometr 3 interior mercury faces do clocklike to move by the transmission of pressure-sensitive film 34.By the gear shift of laminated brush switch 4, we can obtain to set in advance the contact electric signal of soil water potential.For example in advance we fix on the selection shelves of laminated brush switch 4 on 0.5 crust, and when soil suction reached 0.5 crust, sensor can play the effect of electric switch, and starting filling machine or turn on the irrigation pilot lamp plays the effect that control is irrigated.This sensor laminated brush switch 4 has 11 and selects shelves, and they provide 0.1,0.2,0.3,0.35,0.4,0.45,0.5,0.6,0.7,0.8,0.85 crust contact electric signal respectively.

Sensor is worked under condition of negative pressure for a long time, has the micro-leakage phenomenon sometimes and takes place, and the mercury plane is returned less than zero-bit when native water suction force is zero.The setting of zeroing pipe 5 and air-stopping valve 7 can address this problem.When the mercury plane does not return zero, open air-stopping valve 7, the mercury face is promptly got back to zero-bit.

With reference to Fig. 2, it is a U-shaped mercury manometr negative pressure state synoptic diagram.Cause the vacuum tightness of sensor body 2 inside by soil suction, transmit, the mercury face is risen, make air column 32 elongated simultaneously by pressure-sensitive film 34.When not considering the tension force of pressure-sensitive film 34, the shown soil suction of coming out of U-shaped mercury manometr 3, i.e. negative pressure can be expressed from the next: $P=P0-\[\frac{h0}{h1}P0-\frac{(h1-h0)\×2}{76}\]$

In the formula: h ₀---(1 atmospheric pressure, 20 ℃ standard conditions under) air column length during encapsulation is 6 centimetres;

h ₁---the air column height cms in a certain moment;

P ₀---standard atmospheric pressure value (equaling 1);

P---soil suction (negative atmospheric pressure number).

Calculate corresponding contacts according to above-mentioned formula and list in table 1 apart from the distance values of former mercury plane, table 1 has demonstrated mercury slug displacement and shown negative pressure relation.

Table 1

Each contact apart from zero-bit mercury identity distance from (centimetre)	The air pressure (atmospheric pressure) that air column length is reacted	The pressure (atmospheric pressure) that the mercury column difference is shown	Total negative pressure (atmospheric pressure) in the sensor body
				0.56 1.21 1.98 2.88 3.94 5.19 6.64 8.32 9.25 10.24 12.00	0.915 0.832 0.752 0.676 0.604 0.536 0.475 0.419 0.393 0.370 0.333	0.015 0.032 0.052 0.076 0.104 0.137 0.175 0.219 0.242 0.270 0.316	0.100 0.200 0.300 0.400 0.500 0.601 0.700 0.800 0.849 0.900 0.983

In fact, the internal diameter of used U-shaped pipe is not to equate everywhere; And under high suction condition, the tension force of pressure-sensitive film 34 also has certain influence to the mercury lifting height.Therefore, in actual fabrication, the position of each contact can be determined with the method for experiment.Promptly one transparent and in the closed pipeline, pressure gauge is applied the negative pressure of various criterion, measure the physical location that each respective negative is depressed the mercury face.

Theoretical Calculation shows, when mercury by zero-bit (suction is zero) when rising to 12 centimetres, the suction that it indicated is negative 0.983 atmospheric pressure.And in fact can only reach in the sensor about negative 0.85 atmospheric pressure.So it is much of that 12 centimetres of mercury slug displacements are set.

The design of the negative pressure sensor-based system of this sensor is the characteristics separately that comprehensively adopted mercury manometr formula depressimeter, the gentle sensing type depressimeter of air pressure gage formula depressimeter, has satisfied the requirement of contact soil moisture sensor.

Then, in conjunction with embodiment shown in Figure 1, to the design concept and the course of work simple declaration in addition of switching regulator soil moisture sensor described in the utility model.

One arm of U type pipe is closed with the air column of 6 centimeter length, and mercury is equipped with in the bottom of U type pipe, and on the one hand, it moves up and down so that the contact electric signal to be provided under suction function.On the other hand, when negative pressure increases, opposite with negative pressure in the sensing system (suction) direction by the pressure that the mercury slug discrepancy in elevation is produced, it will reduce the distance that air column is elongated under negative pressure, and this just can make manometric size shorten.The other end at the U-shaped pipe is equipped with the pressure-sensitive film, and its effect is to make pressure gauge experience the intrasystem negative pressure of depressimeter on the one hand, and on the other hand, it has been blocked and has contained entering of ionized water, and its pressure sensing is by transfer of air.Because the shortening of whole pressure gauge size, and U-shaped Guan Erduan all is in closed state, the connecting pipe inside of the sensor of just pressure gauge might being packed into.

Adopt the switching regulator soil moisture sensor, its equilibration time will be longer than common depressimeter.Because in negative pressure and the soil suction equilibrium process, the moisture of the pot clay end of flowing through in this kind sensor is with more in sensor.The data of table 2 is after vacuum phenotype depressimeter and switching regulator sensor are imbedded dry ground simultaneously, the soil suction value of depressimeter and soil moisture sensor in the different time, and its unit is a millibar.What deserves to be explained is that the suction value that is measured by the switching regulator soil moisture sensor is lower than depressimeter usually, because its range is a great-jump-forward, therefore, observes after 4 hours, the numerical value of reflection can have been regarded as close with depressimeter.

This data shows that the two differs greatly when on-test, after 4 hours, the soil suction value that the two reflected is close.As the moisture transducer of indication irrigation usefulness, it is embedded in the field for a long time, and such instrument equilibration time can allow.

Table 2

Time	5 minutes	10 minutes	15 minutes	20 minutes	30 minutes	1 o'clock	2.5 the time	4 o'clock	7 o'clock	9 o'clock	14 o'clock
												The depressimeter sensor	357 214	456 303	527 373	599 417	657 465	694 578	730 690	754 714	766 733	769 733	777 748

Adopt the senser element of air pressure gage formula principle in the sensor, influence its mensuration soil suction factors of accuracy and mainly contain two aspects: the one, at the bargain-hunting power section, the length of air column (being the mercury plane) changes less, the relative error that is caused by scale (contact position) is bigger, as when 0.05-0.1 clings to, compare with the mercury column type depressimeter, its relative error can reach 4.5-8.3%; On the other hand, sensor accuracy also is subjected to the influence of temperature and air pressure change, because be that (20 ℃, 1 atmospheric pressure) carry out under standard conditions when the can air column, and is not standard conditions during working sensor, and this will influence its precision.

Table 3 data has been listed the precision of this sensor at different negative pressure sections, its by mercury manometr with reference to demonstration.Generally speaking, lower negative pressure section error is big, and the high negative pressure section is less.When the result of practical measurement showed 10 ℃ of variation of ambient temperature, the error of cell pressure meter was not more than 10 millibars, and its relative error is about ± and 1.7%.

When sensor production, should be taken into account temperature and air pressure factor.When the can air column, should encapsulate according to mean soil temperature and the air pressure data of sensor territory of use irrigation season.On the plateau or mountain area when using, more it should be noted that this point especially.For example, in 1500 meters highlandss above sea level, annual air pressure is about in the of 850 millibars, and therefore, when making sensor, the factor of barometric pressure effect must take in.

Table 3

The negative pressure value of system *(atmospheric pressure)	The negative pressure value (atmospheric pressure) that sensor shows		Relative error (%)
						Correcting temperature causes before the error	Correcting temperature causes after the error		Not during the correcting temperature error	After the correcting temperature error
	0.1013 0.2007 0.2997 0.4000 0.5000 0.6007 0.7020 0.7987 0.9013	0.1123 0.2158 0.3103 0.4139 0.5165 0.6203 0.7238 0.8198 0.9266	0.0934 0.1995 0.2949 0.4003 0.5043 0.6099 0.7154 0.8116 0.9196		10.9 7.5 3.7 3.5 3.3 3.3 3.1 2.6 2.8						7.8 0.6 1.5 0.1 0.8 1.5 1.9 1.6 2.0

Switching regulator soil moisture sensor described in the utility model can be applied to the following aspects:

One, makes the soil moisture alarm

Office or pump house electronic door bell system are introduced in the sensor wiring that is embedded in the field.The laminated brush switch turn-knob is dialled on default suction (as 0.5 crust) shelves.Click button, if pilot lamp is bright, i.e. expression need be poured water, and just can manually start the filling machine and irrigate.

Two, make the soil moisture sensing device of simple automatic irrigation system

In simple automatic irrigation system, soil moisture sensor is connected on the timing relay, by power source for relay control electromagnetic switch or solenoid valve work.This system is applicable to small-sized spray, drip irrigation system.When sensor senses soil lack of water, sensor contact is in conducting state, makes timing relay work, connects solenoid valve, opens the water source and implements to irrigate.Irrigation period is then determined by the timing relay delay time of prior setting.When the electric current of relay is big inadequately, can pass through large-scale A.C. contactor amplified current.This automatic irrigation system cost is lower.

Three, as the soil moisture inductive means of automatic irrigation system programming controller

In the automatic irrigation system of a more complicated, be that programming controller is made at the center often, with the enforcement of commander's subregion irrigation and the switching of various motor rotation and valve by single card microcomputer or microprocessor.At this moment still provide the switch signal by the switching regulator soil moisture sensor according to soil moisture, make relay closes, program controller is by the Automatic Program operation filling machine of setting and the action of valve.

Claims (4)

1, a kind of switching regulator soil moisture sensor, sensor body is a tubular body, one end of sensor body is connected with pot clay end, the other end of sensor body is fixed with lid, it is characterized in that, the inside of sensor body is packaged with the U-shaped mercury manometr, air column is being sealed on the U-shaped pipe one arm top of U-shaped mercury manometr, the pressure-sensitive film in another arm top sealing-in, and the position that the pressure-sensitive film in close sealing-in at this arm top is connected with the zeroing pipe, the inside of this zeroing pipe autobiography sensor body is protruding via lid, on this outwardly directed mouth of pipe, be combined with air-stopping valve, the U-shaped pipe is being equipped with on pressure-sensitive film one arm, be provided with at least two plain conductor contacts, 1 plain conductor contact wherein is below the mercury face, bottom near the U-shaped pipe, it is in conducting state with mercury slug all the time, the lead that joins with it is directly drawn outside sensor body, an external connection as sensor, and the connection lead of remaining plain conductor contact passes sensor body respectively, be welded in proper order on each grade weld tabs of gauge tap, the movable contact spring of gauge tap and another external connection join.

2, switching regulator soil moisture sensor as claimed in claim 1 is characterized in that, described lid is a rubber stopper.

3, switching regulator soil moisture sensor as claimed in claim 2 is characterized in that, described air-stopping valve is connected by the mouth of pipe of soft leather hose with described zeroing pipe.

4, as claim 1,2 or 3 described switching regulator soil moisture sensors, it is characterized in that the number of described plain conductor contact is 12, described gauge tap is a laminated brush switch.

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