Background technology
Along with further going deep into of research work such as accurate irrigation, the collection of crops lack of water information develops to the diversification direction.Physiological change with crop itself reflects that the water regime of crop then is main branch in the crop water shortage research, wherein plant plants stems diameter variation be reflection crop water situation for number seldom can be in one of physical change amount of not destroying continuous coverage under plant body and the plant body normal growth situation, therefore, be used to instruct the potentiality that the crop implementation is accurately irrigated very huge.
At present, plants stems diameter variation measuring transducer all is an imported product.Mainly contain three classes, performance characteristics is as follows: the potentiometer formula: advantage is that price is low, and shortcoming is that mechanical movable electrical contact is arranged, and resolution is low; Strain-type: advantage is no mechanical movable electrical contact, and price is medium, and resolution is medium, and shortcoming has creep to produce; Differential transformer type: advantage is no mechanical armature contact, the resolution height, and shortcoming is a complex structure, costs an arm and a leg.With regard to present product analysis, it is fixed on the sonde configuration complexity on the plants stems stalk, volume and weight is difficult to the littler of making, therefore be not suitable for being used to carry out the diameter variation measurement of the small stem stalk of plant, next present valuable product, Germany produces 2100 yuan one of potentiometer formula, and is the non-standard output without conversion, be not transmitter truly, the differential transformer type transmitter surpasses 4000 Renminbi.
Summary of the invention
The objective of the invention is to overcome the deficiencies in the prior art and provide that a kind of sonde configuration is simple, volume is little, in light weight, price is low, resolution is high, do not have mechanical movable electrical contact, creep resistant, the wet plant haulm diameter variation measuring transducer of moisture resistance, the diameter variation that is particularly suitable for the small cane of plant is measured.
The object of the present invention is achieved like this: comprise measuring sonde that is fixed on the plant haulm and the treatment circuit that is connected with measuring sonde, measuring sonde is provided with plant haulm diameter and expands and shrink and the corresponding movable jacking that moves radially takes place, movable jacking is connected with magnet steel by drive link, corresponding magnet steel is provided with the mistor bridge on measuring sonde, and the mistor bridge is connected with treatment circuit by the probe extension line.Lead screw is fixed on the frame part that constitutes measuring sonde on the fixed support by holding screw, and fixedly jacking is set on fixed support, corresponding fixedly jacking is provided with movable jacking by drive link on fixed support, and between movable jacking and fixed support, back-moving spring being set, magnet steel, the drive link that is connected with magnet steel and mistor bridge are installed in the shell of probe.The N utmost point of magnet steel or the S utmost point are positioned at the oblique upper of mistor bridge, and magnet steel is along with the expansion contraction of plants stems stalk moves horizontally, and the effective range that moves can not surpass the mistor bridge and be in the scope of saturation magnetic field.The mistor bridge adopts two strong magnetic metal film mistor R1 and R2, the face that will be printed on model all up, the end alignment of R1 and R2 lead-in wire opposite not being had lead-in wire is close together, the c end of R1 and a end of R2 are connected together as the constant current power supply anode of mistor bridge, the a end of R1 and the c end of R2 are connected together as the constant current power supply negative terminal of mistor bridge, hold signal to amplify positive output end the b of R1 as the mistor bridge, hold signal to amplify negative output terminal the b of R2 as the mistor bridge, be connected on the treatment circuit by extension line, the leaded two ends of mistor bridge are placed vertical with the moving direction of magnet steel up and down, and in same plane.The constant current power supply anode of mistor bridge is connected in the anode of the constant current power supply of treatment circuit, the constant current power supply negative terminal of mistor bridge is connected in the negative terminal of the constant current power supply of treatment circuit, the signal of mistor bridge amplifies positive output end, be connected in the positive input terminal of the signal amplification of treatment circuit, the signal of mistor bridge amplifies the negative input end that negative output terminal is connected in the signal amplification of treatment circuit.
The present invention has adopted the sensitive element of novel magneto sensor strong magnetic metal film mistor as transmitter probe, utilize strong magnetic metal film mistor resistance value in following characteristic of saturation magnetic field intensity to the magnetic direction sensitivity, two mistors are formed resistance bridge (in four magneto sensors are arranged) to improve sensitivity, simultaneously resistance bridge is adopted the constant current power supply, because the auto-compensation of mistor bridge joint and constant current power supply significantly reduce the transmitter temperatures coefficient, sonde configuration of the present invention, under saturation magnetic field, work, avoided effectively being operated under the unsaturation magnetic field and to have improved resolution and be subject to have magnetic hysteresis, the problem of poor repeatability under ground magnetic interference and the unsaturation magnetic field.Sonde configuration output signal amplitude of the present invention is big, therefore needn't adopt expensive very accurate integrated circuit, has reduced the cost of manufacture of transmitter.Adopt technical scheme of the present invention, probe has very simple physical construction, and properties of product are better than existing product, and cost of manufacture is lower than 200 yuans.Therefore the present invention have simple in structure, volume is little, in light weight, price is low, resolution is high, do not have mechanical movable electrical contact, creep resistant, the wet advantage of moisture resistance.
Embodiment
As shown in Figure 1, 2, the present invention includes measuring sonde that is fixed on the plant haulm 6 and the treatment circuit that is connected with measuring sonde, measuring sonde is provided with plant haulm 6 diameters and expands and shrink and the corresponding induction installation that moves radially takes place, this induction installation is connected with magnet steel 1, corresponding magnet steel 1 is provided with mistor bridge 2 on measuring sonde, and mistor bridge 2 is connected with treatment circuit by probe extension line 12.
It is described that to expand and shrink and the corresponding induction installation that moves radially takes place with plant haulm 6 diameters be a kind of movable jacking 7 that is installed on the plant haulm 6, movable jacking 7 is connected with magnet steel 1 by drive link 4 on fixed support 9, lead screw 10 is fixed on the frame part that constitutes measuring sonde on the fixed support 9 by holding screw 11 simultaneously, and fixedly jacking 8 is set on fixed support 9, be plant haulm 6 between jacking 8 and the movable jacking 7 fixedly, between movable jacking 7 and fixed support 9, also be provided with back-moving spring 5, magnet steel 1, drive link 4 that is connected with magnet steel 1 and mistor bridge 2 are installed in the shell 3 of probe.
The N utmost point of magnet steel 1 or the S utmost point are positioned at the oblique upper of mistor bridge 2, and magnet steel 1 is along with the expansion contraction of plants stems stalk moves horizontally, and the effective range that moves can not surpass the mistor bridge and be in the scope of saturation magnetic field.
Drive link 4, back-moving spring 5, lead screw 10 adopts non-magnetic conduction, stainless steel material that intensity is good to make, and other parts adopt non-magnet materials, for aluminium alloy is preferably used in weight reduction.
By by fixed support 9, lead screw 10, holding screw 11, the fixing fixed part formed of jacking 8, movable jacking 7, back-moving spring 5, the measure portion of being made up of magnet steel 1, mistor bridge 2, drive link 4, back-moving spring 5, movable jacking 7 that will be connected with shell 3 is fixed on the plant haulm 6.When the flow of water of plant changes, the corresponding expansion and contraction takes place in the diameter of plant haulm 6 thereupon, this expansion and contraction, the movable jacking 7 of elastic force compressing on plant haulm that drives by back-moving spring 5 taken place to move radially accordingly, this moving radially by drive link 4 makes the magnet steel 1 and fixing mistor bridge 2 generation relative motions that is fixed on the drive link 4, this relative motion makes the magnetic direction generation respective change that acts on mistor bridge 2, and the variation of this magnetic direction is converted into voltage by mistor bridge 2 variation is connected on the treatment circuit by probe extension line 12 and is for further processing.
As shown in Figure 3, mistor bridge 2 of the present invention adopts two strong magnetic metal film mistor R1 and R2, the face that will be printed on model all up, the end alignment of R1 and R2 lead-in wire opposite not being had lead-in wire is close together, the c end of R1 and a end of R2 are connected together as the constant current power supply anode (No. 5 ends) of mistor bridge, the a end of R1 and the c end of R2 are connected together as the constant current power supply negative terminal (No. 4 ends) of mistor bridge, hold signal to amplify positive output end (No. 3 ends) b of R1 as the mistor bridge, hold signal to amplify negative output terminal (No. 2 ends) b of R2 as the mistor bridge, be connected to by extension line on the corresponding port of interface J1 of treatment circuit, the leaded two ends of mistor bridge 2 are placed vertical with the moving direction of magnet steel 1 up and down, and in same plane.
The constant current power supply anode (No. 5 ends) of mistor bridge 2 is connected in the anode of the constant current power supply of treatment circuit, the constant current power supply negative terminal (No. 4 ends) of mistor bridge 2 is connected in the negative terminal of the constant current power supply of treatment circuit, the signal of mistor bridge 2 amplifies positive output end (No. 3 ends), be connected in the positive input terminal of the signal amplification of treatment circuit, the signal of mistor bridge 2 amplifies the negative input end that negative output terminal (No. 2 ends) is connected in the signal amplification of treatment circuit.
It is i.e. R1 and the R2 among the figure of two of strong magnetic metal film mistors of RCM01 that the mistor bridge adopts the model of T092-S encapsulation.Be connected into resistance bridge with two mistors and not only can improve sensitivity, because the auto-compensation of bridge joint, temperature coefficient also is able to remarkable minimizing.
As shown in Figure 4, the present invention is connected into resistance bridge (in four magneto sensors are arranged) with two mistors, sensitivity is doubled, the output signal amplitude is big, therefore needn't adopt expensive very accurate integrated circuit, integrated circuit U1 adopts cheap, the AM400 of perfect in shape and function (paster encapsulation).The function of treatment circuit mainly contains two, and one is for the mistor bridge provides the constant current power supply, and another is the signal that probe is exported further to be amplified and be transformed into standard signal to export.The constant current power supply anode (No. 5 ends) of mistor bridge is by No. 5 ends of treatment circuit interface J1, be connected in the anode of the constant current power supply of treatment circuit, the constant current power supply negative terminal (No. 4 ends) of mistor bridge is by No. 4 ends of treatment circuit interface J1, be connected in the negative terminal of the constant current power supply of treatment circuit, the signal of mistor bridge amplifies No. 3 ends of positive output end (No. 3 ends) by treatment circuit interface J1, be connected in the positive input terminal of the signal amplification of treatment circuit, the signal of mistor bridge amplifies No. 2 ends of negative output terminal (No. 2 ends) by treatment circuit interface J1, is connected in the negative input end of the signal amplification of treatment circuit.On No. 1 termination probing shell 3 of J1.Provide suitable constant current power supply value by adjusting continuous current adjustment resistance R 3 for the mistor bridge, the voltage signal output amplitude is adjusted potentiometer RV1 and potentiometer RV3 is adjusted in voltage output zero point by adjusting, make No. 2 ends of voltage output end J2, the standard signal of output transducer, 0~5V or 0~10V.Adjust potentiometer RV2 and electric current output sampling resistor R2 by adjusting current signal output initial value, make No. 4 ends of current output terminal J2, the standard signal of output transducer, 4~20mA or 0~20mA.
As one embodiment of the present of invention, U1 is AM400 (paster encapsulation), and the strong magnetic metal film mistor adopts RCM01, and single magneto sensor does not add field resistance 2.25K, and R3 gets 260 Ω, transmitter supply voltage 24V (DC).