Background technology
Since the reform and opening-up, the rapid economic development of China, economic construction has obtained remarkable achievement.Yet, all conglomeraties but are to be that cost exchanges economic temporary transient prosperity for sacrificialing environment and resource, the enterprise of some highly energy-consumings, high pollution has brought huge pressure for the environment and the resource of China, and in the long run, this will restrict further developing of China's economy.The sewage discharge and the monitoring of environmental water quality of control enterprise all need to use a large amount of water quality on-line monitoring instrument devices, and (≤5ml) water sample to be checked and reagent measures these appliance requires to trace.The precision of measuring apparatus and reliability have directly determined the accuracy of testing result and the reliability of instrument.
The principle of gauge line is generally all adopted in the liquid volume metering that is applied to the water quality on-line monitoring instrument device at present, promptly utilizes probe or photoelectric sensor that the liquid level of setting volume is responded to, again by Electric Machine Control syringe pump or the metering of peristaltic pump feed liquor.This class measuring apparatus is for guaranteeing measuring accuracy, general sampling amount all big (〉=5ml), it is dumb also to exist sample size simultaneously, can only measure the defective of several fixed volumes, and can not eliminate bubble in the liquid to the influence of measurement result, poor reliability, simultaneously probe or sensor are vulnerable to the strong sewage infringement of corrosivity, make the degree of accuracy of entire equipment be subjected to the restriction of liquid sensor precision.
And the measuring apparatus of present water quality on-line monitoring instrument device only is applicable at fixing environmental monitoring sites regular monitoring is carried out in fixing waters, and be not suitable for the monitoring and the dynamic monitoring of accident, especially be unsuitable for the water quality monitoring instrument and in stormy waves such as lake, ocean, vehicle-mounted, mobile water quality monitoring car and the environment that jolts, use.
Traditional liquid meter all is to use current to flow through and promote the counting wheel rotation and come metered flow, and for example the patent No. is the lightweight IC-card water meter of ZL200420117890.6.Complicated in mechanical structure, be difficult to reach airtight and etch-proof effect, and bigger to getting ten milliliters of following difficulty of liquid, and if we to measure the liquid that sewage etc. may contain algae or floccus and must influence the suffered friction of counting wheel rotation, thereby influence measuring accuracy.
And for example the patent No. is the time pulse control step formula quantitative watering machine of CN86200994U and the contactless fluid flow indicating device that the patent No. is ZL91103249, though reached etch-proof effect, but its internal mechanical complex structure, still be not suitable for metering to sewage, result in blockage easily, all only be suitable for measuring than clean liquid.
As seen, the water quality on-line monitoring instrument device requires little liquid measure (getting liquid measure is about 1 milliliter) is carried out accurately, measured reliably at present, but the measuring apparatus of prior art design all exists significant disadvantages, especially can't satisfy the request for utilization in lake, ocean, stormy waves such as vehicle-mounted and the environment that jolts.
Summary of the invention
Problem at the prior art existence, the invention provides a kind of Pointwise scanning type micro-fluid metering device, it is characterized in that: comprise that N leads to valve, airtight anticorrosion fluorine rubber-pipe, peristaltic pump, liquid liquid outlet, control computation unit and two detector of liquid Y1 and Y2; In the logical valve of described N, 1-1 is an air scoop, and 1-i is inlet, wherein i=2 ... N; The logical valve of described N is connected with Y2 with described detector of liquid Y1 successively by described airtight anticorrosion fluorine rubber-pipe, the other end of described airtight anticorrosion fluorine rubber-pipe is connected with an end of described peristaltic pump, and the other end of described peristaltic pump is connected with described liquid liquid outlet; Described control computation unit is connected with Y2, described peristaltic pump with the logical valve of described N, described detector of liquid Y1 respectively.
The present invention also provides a kind of use method of Pointwise scanning type micro-fluid metering device measurement liquid as described, may further comprise the steps: demarcate described Pointwise scanning type micro-fluid metering device; Calculate when measuring required liquid, liquid detects the times N value; Control computation unit is opened inlet 1-i, opens stepper motor, drives the peristaltic pump entry into service, and the logical valve of N extracts liquid; During no liquid, detector of liquid Y1 output low level state is delayed time 1 millisecond, and when control computation unit monitors detector of liquid Y1 when becoming high level by low level, express liquid detecting device Y1 detects liquid, and got liquid volume this moment is mi*V
Unit, mi>1 and be integer wherein, V
Unit=dt * v * A, dt are the trace interval of control computation unit, and the flow velocity when v is the liquid sample introduction, A are that pipeline section is long-pending; Liquid continues to flow along pipeline, getting liquid measure increases gradually, simultaneously, detecting device Y1 every 1 millisecond of detection once, if detector of liquid Y1 within a certain period of time the number of times i of tracer liquid less than the N value that calculates, then detector of liquid continues to detect, up to i 〉=N, peristaltic pump shuts down, and closes inlet 1-i, open operation valve 1-1 and blow, measurement is finished.
Apparatus of the present invention can be carried out bubble and proofread and correct, bearing calibration is: when getting the liquid measurement, the scanning detection signal that monitors detector of liquid Y1 when control computation unit becomes low level by high level, be that detector of liquid Y1 detects and contains bubble in the liquid, then control computation unit is not carried out the metrological operation step, continue the scanning detection signal of monitoring liquid detecting device Y1, if control computation unit monitors detector of liquid Y1 and was in low level state (being that detector of liquid Y1 has not detected liquid) in continuous 60 seconds, then control computation unit is sent alerting signal, and withdraw from the measurement flow process, bubble is proofreaied and correct.
Embodiment
Be illustrated in figure 1 as a kind of Pointwise scanning type micro-fluid metering device theory structure synoptic diagram, apparatus of the present invention mainly by: N leads to valve 1, airtight anticorrosion fluorine rubber-pipe 2, peristaltic pump 3, liquid liquid outlet 4, control computation unit 5, detector of liquid Y1 and Y2 seven parts are formed, wherein in the logical valve 1 of N, 1-1 is an air scoop, and 1-i is inlet (i=2 wherein ... N).The logical valve 1 of N is connected with detector of liquid Y1, Y2 by airtight anticorrosion fluorine rubber-pipe 2 in order, and the other end of airtight anticorrosion fluorine rubber-pipe 2 is connected with an end of peristaltic pump 3, and the other end of peristaltic pump 3 is connected with liquid liquid outlet 4; Control computation unit 5 is connected with Y2, peristaltic pump 3 with the logical valve 1 of N, detector of liquid Y1 respectively.Wherein the logical valve 1 of N is used for the air inlet of the feed liquor and the gas of metering liquid; Airtight anticorrosion fluorine rubber-pipe 2 is pipelines of liquid flow; The major function of control computation unit 5 is: at peristaltic pump at the uniform velocity under the condition of sample introduction, utilize the state of 5 pairs of two detector of liquid of control computation unit to scan (1 millisecond/time) fast, simultaneously gas admittance valve in the logical valve of N and feed liquor valve are carried out high-speed switch control, thus very sensitive, get the liquid of trace accurately and reliably; Liquid liquid outlet 4 is used for discharged liquid; Whether detector of liquid Y1 and Y2 are used for tracer liquid and flow through.
Fig. 2 is a demarcation schematic flow sheet of the present invention, and demarcation flow process and scaling method that measuring apparatus of the present invention is concrete are as follows:
The first step: setting from inlet 1-i to the liquid volume the detector of liquid Y1 is Vi (Vi the unknown);
The logical valve 1 of control computation unit 5 control N is opened the inlet 1-i that needs demarcation, starts stepper motor, drives peristaltic pump 3 and is rotated counterclockwise, and liquid flows into airtight anticorrosion fluorine rubber-pipe 2, and before detector of liquid Y1 detected liquid, peristaltic pump 3 entered at the uniform velocity state.Output low level state during no liquid in the detector of liquid Y1.When monitoring continuous 1 second of detector of liquid Y1, control computation unit 5 becomes high level state (being that detector of liquid Y1 detects liquid) by low level, the 5 record current time of control computation unit are t1, close the logical valve inlet 1-i of N simultaneously, the air scoop 1-1 that opens the logical valve of N blows.
Behind the liquid sample introduction, if control computation unit 5 monitors detector of liquid Y1 and was in low level state in continuous 60 seconds always, then no liquid is flowed through in the detector of liquid Y1, and control computation unit 5 is sent alerting signal, and control N leads to valve 1 and peristaltic pump 3 quits work, and withdraws from the demarcation flow process.
Peristaltic pump 3 remains in operation, and such one section is continued along pipeline mobile from inlet 1-i to the liquid measure Vi the detector of liquid Y1.Become low level state (being that detector of liquid Y1 detects no liquid) if control computation unit 5 monitors continuous 1 second of detector of liquid Y1 by high level, then this section liquid measure Vi leaves detector of liquid Y1, and the 5 current times of record of control computation unit are t2.
Liquid continues to flow along pipeline, when monitoring continuous 1 second of detector of liquid Y2, control computation unit 5 becomes high level state (being that detector of liquid Y2 detects liquid) by low level, at this moment, this section liquid measure Vi has arrived detector of liquid Y2, and the 5 current times of record of control computation unit are t3.
If control computation unit 5 monitored detector of liquid Y2 in continuous 60 seconds and is in low level state (being that detector of liquid Y2 does not detect liquid) always, then detector of liquid Y2 does not have liquid to flow into, control computation unit 5 is sent alerting signal, and control N leads to valve 1 and peristaltic pump 3 quits work, and withdraws from the demarcation flow process.
Peristaltic pump 3 remains in operation, and liquid continues to flow, discharge from liquid outlet 4, and the emptying pipeline, system returns.
Pointwise scanning type micro-fluid metering device of the present invention will be referred to the basic volume unit of this measuring apparatus special use: V in demarcation and measuring method
UnitV
UnitWhen in anticorrosion fluorine rubber-pipe 2, flowing for liquid, the small substantially volume unit that device can monitor out in theory, the trace interval of supposing control computation unit 5 is dt=1 millisecond (ms), and the flow velocity during the liquid sample introduction is v=10mm/s, and pipeline section amasss A=3.14mm
2, V then
Unit=dt*v*A=0.0000314 milliliter.All volumes of mentioning all will be with V herein
UnitRather than nominal volume unit (as milliliter) is as base unit.
According to the demarcation flow process of system of the present invention described above, liquid volume Vi was directly proportional with mistiming between t1, t2 as can be known, and relational expression is as follows:
Vi=(t2-t1)*V
unit/1ms=(Δt1/1ms)*V
unit=mi*V
unit (1)
Mi>1 and be integer wherein
Second step: accurately to the liquid measure AL the Y2 (generally being controlled at about 1ml), wherein A is that pipeline section is long-pending from detector of liquid Y1 in demarcation, and L is that detector of liquid Y1 is to the distance between the Y2.The mistiming that obtains between time t3 and the t1 is directly proportional with liquid measure AL, and relational expression is as follows:
AL=(t3-t1)*V
unit/1ms=(Δt2/1ms)*V
unit=K*V
unit (2)
K>1 and be integer wherein
Because for each instrument, after measuring apparatus installed, the distance L of pipeline and each sample introduction port were all fixed to the distance of Y1 between Y1 and Y2, therefore, K and mi are fixed values, can decide by demarcation, promptly
mi=(Δt1/1ms)=(t2-t1)/1ms
K=(Δt2/1ms)=(t3-t1)/1ms
The 3rd step: when needs when 1-i mouth sample introduction measures, suppose that needing the volume of sample introduction is V, then can be with V V
UnitUnit representation is (V
UnitApproximate volume be 0.0000314 milliliter):
V=Vi+N*V
unit
That is: V=(mi+N) * V
Unit(3)
So: N=(V/V
Unit)-mi
Wherein N is flow of liquid should be scanned liquid when detector of liquid Y1 a number of times, accurately controls the N value and can accurately control and get liquid measure.
Utilize control computation unit 5 to adopt the demarcation flow process of Fig. 2 that gas admittance valve and feed liquor valve high-speed switch in the logical valve of N are controlled, thereby very accurately get the liquid of trace reliably.
For guaranteeing the sample introduction measuring accuracy, behind pipeline between replacing motor, the logical valve of N or detecting device Y1, Y2, system all should demarcate once again.
Fig. 3 is a measurement schematic flow sheet of the present invention.Measure if desired from inlet 1-i and get the liquid that volume is V.At first according to the formula and the mi value of having demarcated, calculate when measuring required liquid, liquid detects the times N value.For example: calculating the volume of measuring required liquid according to formula (3) is (mi+N) individual base unit V
Unit, calculating N is 30000 times.When getting the liquid metering, control computation unit 5 is opened inlet 1-i, open stepper motor, drive peristaltic pump 3 entrys into service, the logical valve 1 of N extracts liquid, during no liquid, detector of liquid Y1 output low level state is delayed time 1 millisecond, becomes high level when control computation unit 5 monitors detector of liquid Y1 by low level, be that detector of liquid Y1 detects liquid, got liquid volume this moment is mi*V
UnitLiquid continues to flow along pipeline, getting liquid measure increases gradually, simultaneously, detecting device Y1 every 1 millisecond of detection once, if the number of times that detector of liquid Y1 detects liquid within a certain period of time (is i<N) less than the N value that calculates, then detector of liquid continues to detect, (is that i 〉=N), peristaltic pump 3 shuts down, and closes inlet 1-i up to detector of liquid Y1 tracer liquid number of times greater than the N value that calculates, open air scoop 1-1 and blow, measurement is finished.
By above measurement flow process, accurately control detection times N value can accurately be got milliliter little liquid measure liquid of level.
The present invention also provides the bubble calibration function: when getting the liquid measurement, if contain bubble from the liquid that inlet takes out, the so actual liquid of obtaining will be less slightly, gets the liquid error thereby produce.Therefore need proofread and correct bubble.Concrete bearing calibration is as follows:
When getting the liquid measurement, if detector of liquid Y1 detects liquid, control computation unit 5 monitors detector of liquid Y1 and becomes high level by low level, the scanning detection signal that monitors detector of liquid Y1 when control computation unit 5 becomes low level by high level, be that detector of liquid Y1 detects and contains bubble in the liquid, then control computation unit 5 is not carried out the metrological operation step, continue the scanning detection signal of monitoring liquid detecting device Y1, if control computation unit 5 monitors detector of liquid Y1 and was in low level state (being that detector of liquid Y1 has not detected liquid) in continuous 60 seconds, then control computation unit 5 is sent alerting signal, and withdraw from the measurement flow process, bubble is proofreaied and correct.
The present invention compares with prior art, has the following advantages:
(1) being applicable to that various liquid to a plurality of passages measure respectively gets liquid;
(2) the contactless liquid of getting measures in the closed conduit;
(3) can realize accurately quantitative liquid getting of milliliter level;
(4) pipe path mechanism is simple, is difficult for stopping up;
(5) have the bubble calibration function, eliminated the influence of bubble measurement result;
(6) be applicable to that the water quality monitoring instrument uses in stormy waves such as lake, ocean, vehicle-mounted, mobile water quality monitoring car and the environment that jolts.
The present invention embodiment disclosed herein is exemplary, and it only is for explanation that the present invention is made an explanation, and is not limitation of the present invention, for example, can adopt syringe pump to replace peristaltic pump; Can replace multiport valve with the multichannel selection valve.It will be appreciated by those skilled in the art that these predictable improvement and expansion are included within protection scope of the present invention.