CN2177240Y

CN2177240Y - Capacitance matter water content investigator

Info

Publication number: CN2177240Y
Application number: CN 93212522
Authority: CN
Inventors: 冯国良; 施青松; 胡溶溶
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-05-13
Filing date: 1993-05-13
Publication date: 1994-09-14
Anticipated expiration: 2003-05-13

Abstract

The utility model relates to a capacitance matter water content investigator which solves the problem of ubiquitous low testing precision and poor reproducibility of high moisture materials of the capacitance matter water content investigator. The utility model is composed of a measuring barrel, a blanking barrel, the ac and the dc power supply converters. The surfaces of the circular barrel and the center cylinder of the measuring barrel take the measure of insulation, which overcomes measuring errors caused by a leak resistance. The utility model is used for moisture determination of granular and powdery food supplies, oil-bearing materials and feedstuff. The utility model has the advantages of stable performance, high determining precision and no special requirements for environment.

Description

Capacitance matter water content investigator

The utility model belongs to the measurement instrument class, exactly, is a kind of condenser type material moisture determination instrument device, is mainly used in the moisture determination of graininess and powdered grain, oil plant and feed.

In various material water tester devices, the condenser type moisture determination instrument has that sampling amount is big, sample need not pulverized, and therefore accuracy and reappearance are generally adopted than characteristics such as height.The Decree of Patent Office of China 88201964.3,87206844U, 86210321U patented claim just belong to this quasi-instrument.Practice shows, low, the poor reproducibility of accuracy when existing condenser type moisture determination instrument still exists high moisture content material test; Can not adapt to the kind that has than big-difference; Test result is subjected to problems such as the influence of environment temperature (wetting) degree is bigger.Factor except the aspects such as hardware, software and mathematical model of instrument, a main cause that the problems referred to above occur is that the good insulation performance measure is not taked at capacitive transducer the two poles of the earth, when medium moisture content is higher, two interpolars of capacitive transducer form very important leakage resistance, thereby influenced correct mensuration, caused material moisture to be difficult for surveying accurate dielectric capacitance.In addition, because ac-dc power converter is generally the built-in instrument bottom that places, magnetic field that produces during its work and heat also are the factors that appearance and thermometric correctness are surveyed in influence.

The purpose of this utility model is a kind of material moisture determination instrument that can effectively avoid causing because of capacitive transducer two interelectrode leakage resistances measuring error of design, improve the measurement accuracy of condenser type material moisture determination instrument, guarantee that capacitive transducer two interpolars reliably insulate, and the interference that test circuit is subjected to reduces to the scope of permission.

The utility model adopts the measuring cup type structure, forms by measuring tube, blanking barrel and ac-dc power converter.Measure tube and comprise capacitive transducer, temperature sensor, test circuit, LCD and finger-board etc.Test circuit is measured circuit, temperature measuring circuit and auxiliary circuit by single-chip microcomputer, electric capacity and is formed.Two electrodes of capacitive transducer are made up of circular cylinder and the centered cylinder of measuring tube, and are at circular cylinder and centered cylinder surface spraying insulation course, good to guarantee the insulation of capacitive transducer two interpolars.Ac-dc power converter places measures the tube outside.Physical basis of the present utility model is the electric capacity determination method, and promptly the mensuration of material moisture content is to realize by the dielectric capacitance of measuring its moisture content of reflection.Because the temperature of tested material also influences the mensuration of dielectric capacitance, so the utility model is actually by measuring the dielectric capacitance and the medium temperature of tested material, by the certain mathematical model and the parameter of this material kind, after data processing, obtain the water content of tested material.Principle of work of the present utility model, primary structure, manipulate method and technique effect, roughly the same with the condenser type moisture determination instrument that generally adopts, it solves the influence of leakage resistance to moisture measurement emphatically, taked the spraying insulation course, supply convertor has been moved to measures such as machine is outer, make capacitive transducer not influenced by leakage resistance, thereby guarantee the accuracy that high moisture content material is measured.

Owing to taked insulation measures at capacitive transducer two interpolars, improved the accuracy and the reappearance of condenser type material moisture determination instrument, its advantage is especially obvious in the measurement of high moisture content material.Ac-dc power converter is moved to outside the machine, alleviated instrument effectively and surveyed the interference that appearance, temperature measurement circuit and each element function, parameter, circuit distributed capacitance, oscillation frequency etc. are subjected to.

Accompanying drawing 1 is the utility model synoptic diagram.

Accompanying drawing 2 is the utility model electricity functional-block diagram.

Now be described with reference to the accompanying drawings the utility model: 1, measure tube; 2, ac-dc power converter; 3, outlet; 4, display; 5 finger-boards; 6, blanking barrel; 7, blanking barrel bayonet lock; 8, circular cylinder; 9, centered cylinder; 10, capacitive transducer; 11, temperature sensor; 12, survey capacitive circuit; 13, temperature measurement circuit; 14, crystal oscillator; 15, single-chip microcomputer; 16, display driver circuit; 17, latch; 18, memory under program; 19, data memory; 20, tri-state gate circuit.

The blanking barrel (6) of earlier standard specimen of specified volume being packed into, press blanking bayonet lock (7) after, standard specimen is flowed into by the blanking barrel freely falling body and measures tube (1).Moisture sensor is the cylindrical capacitance sensor that is made of circular cylinder (8) and centered cylinder (9).After material entered, just forming with the standard specimen was the equivalent capacity of medium, and participated in the work of RC monostable oscillatory circuit.The oscillation frequency of monostable circuit is directly controlled by single-chip microcomputer (15).When the R of monostable circuit value fixedly the time, the duration of charging Tx direct ratio dielectric capacitance of monostable circuit just can be tried to achieve dielectric capacitance Cx by the mensuration to duration of charging Tx.As seen, the test to dielectric capacitance is to realize by the mensuration to the RC duration of charging.In whole analysis, calculating, supposed that capacitor two interpolars are no leakage resistances, this allows when material moisture content is relatively lower, but when material moisture content was higher, material formed a leakage resistance of can not ignore at capacitor two interpolars, is parallel to dielectric capacitance Cx, thereby make the charging current shunting, cause the variation in duration of charging, cause surveying the error of holding data, thereby cause the water cut of the high moisture content material of indeterminacy.Present embodiment is taked the measure at the circular cylinder (8) of measuring tube and centered cylinder (9) surface spraying insulating material, to guarantee the reliable insulation at capacitive transducer the two poles of the earth.In addition, ac-dc power converter is moved to outside the measurement tube, also further guaranteed to survey the operate as normal of appearance, temperature measurement circuit.After taking abovementioned technology, can overcome the existing shortcoming that exists with quasi-instrument effectively, guarantee under high moisture content situation, still can accurately record material moisture.

Claims

1, a kind of condenser type material moisture determination instrument, comprise blanking barrel 6 and ac-dc power converter 2 and the measurement tube of forming by capacitive transducer 10, temperature sensor 11, test circuit, display 4, finger-board 51, it is characterized in that measuring the circular cylinder 8 of tube and the two poles of the earth that centered cylinder 9 forms capacitive transducer, at their surface spraying insulation course.

2, according to described electric capacity of claim 1 or moisture determination instrument, it is outside to it is characterized in that power of alterating and direct current interchanger 2 is positioned at the measurement tube.