CN1144033C - Container leakage detecting method and detector - Google Patents

Abstract

The present invention provides a method for detecting leakage of a container and a detecting device thereof. The method for detecting leakage of a container is used for quickly and accurately detecting the leakage of the container. The method is characterized in that a computing device controls that a detected container and a balancing container are simultaneously inflated and pressurized, and then the detected container and the balancing container are mutually closed and isolated; pressure difference between the two containers is detected and is computed by the computing control device, and a leakage specific volume rate, a leakage rate or leakage amount is displayed and given out.

Description

Method for detecting leakage of container and device

What the present invention relates to is method and the pick-up unit that detection receptacle is leaked, and especially the slight leakage of container is carried out the method for detecting leakage of container and the device of accurate and fast detecting.

In the prior art, for compensate because of the caused influence of temperature variation of the compressibility of gas to guarantee accuracy of detection, must before detection, make with tested container co-content, same shape, with material and absolute leak free equalizing reservoir.When the quality of tested container changes, also must change and the corresponding equalizing reservoir of tested container thereupon.The both unfavorable in actual applications shortening sense cycle of this specific (special) requirements to equalizing reservoir also is unfavorable for reducing and cuts out cost.For the tested container that solves different cultivars uses same equalizing reservoir to detect, the inventor of present patent application had once applied in Japan that application number was the flat 4-346347 patent of special hope.But, this patent requires to wait means to be determined in advance by experiment to the heat conductivility of equalizing reservoir, and then the knee characteristic of the differential pressure curve by the actual detected gained tries to achieve the heat balance time of system, and the pressure difference when reaching thermal equilibrium state according to system is again asked for leak rate.It is uncontrollable that this makes that this method has a sense cycle, and especially the quite long shortcoming of some sense cycle makes this method can not realize that fast detecting also is difficult to adopt on automatic assembly line.

Purpose of the present invention, be exactly according to the deficiencies in the prior art, and develop on its basis and provide and not adopt specific equalizing reservoir, and be equalizing reservoir with the testing environment, or adopt fixing equalizing reservoir really to need not its heat conductivility is measured in advance, and it is short to reach sense cycle, the technical scheme of the device that the detection method that measuring accuracy is high is made with this method of use.

The present invention finishes by following technical solution, it adopts tested container and equalizing reservoir is inflated pressurization simultaneously, and will be at this moment as clocking starting time, record inflationtime ta when two container inner pressures reach detected pressures, when the time reaches the pressure time tb of setting, with source of the gas and tested container, isolated mutually between equalizing reservoir and two containers, sealing, pressure reduction D between beginning detection record two containers, institute's pressure measurement difference and time relationship are constituted pressure reduction function D (T), under the step response of DH as the non-oscillatory second-order system, again with this pressure reduction function as the be in series step response of system of inertial element and delay link; Obtain the pressure reduction function expression and try to achieve leakage specific volume speed or the leak rate or the leakage rate of container.

Utilize above-mentioned method for detecting leakage of container; the invention provides the container leakage pick-up unit; it is by pneumatic supply 10; filtrator 11; pressure is set valve 12; tensimeter 13; solenoid valve 14; 15; 1 and differential pressure pick-up 17; the leak detecting device that tested container connection valve 20 and equalizing reservoir 19 connect into by pipeline; characteristics are simultaneously with pipeline and connect a protection solenoid valve 18 at the two ends of described differential pressure pick-up 17; also to be provided with in addition by detecting input circuit; the calculation control device that controlling output circuit and microsystem constitute; and the electrical output signal of differential pressure pick-up 17 is connected with the detection input circuit of calculation control device, and the control signal of microcomputer output is by controlling output circuit and solenoid valve 14; 15; 16; 18 do electric control connects.

Adopt method and apparatus provided by the present invention to carry out container leakage and detect, because environment temperature cause has been compensated when the Microcomputer Calculation automatically to the influence of detection, so the requirement of testing environment is relaxed.Because leaking specific volume speed is to change the pressure reduction array general status that records in time according to pressure reduction to be tried to achieve by Microcomputer Calculation, therefore to the influence of the discretization error of pressure reduction self and noise error etc., in the Microcomputer Calculation process, compensated automatically, so make Leak Detection can obtain very high precision.Have the detection of pressure reduction to be controlled by the time again, the control procedure of whole detection and calculating all is again to be carried out by microcomputer, therefore

Can shorten sense cycle greatly and realize fast detecting, therefore extremely suit on automatic assembly line, to use, also boundless to the scope surveyed that is suitable for simultaneously.This shows that the present invention compared with prior art really has outstanding substantive distinguishing features and obvious improvement.

Description of drawings:

Fig. 1 is the pneumatic circuit synoptic diagram of container leakage pick-up unit of the present invention;

Fig. 2 is the pressure reduction song that is made of the measured pressure reduction array of container leakage pick-up unit of the present invention

Line chart;

Fig. 3 is the composition decomposing schematic representation of pressure reduction;

Fig. 4 is the structure block diagram of calculation control device;

Below by specific embodiment the present invention is further elaborated.Fig. 1 is the pneumatic circuit synoptic diagram of container leakage pick-up unit among the present invention.This scheme is to be provided with a fixing general equalizing reservoir 19, and it can adapt to the needs that all kinds of tested containers detect.But equalizing reservoir 19 must be that heat conductivility is stable, does not have distortion and leak free container.Pneumatic supply 10 among the figure, and it is identical with tensimeter 13 with the effect of aforementioned schemes that filtrator 11, pressure are set valve 12. Solenoid valve 14,15,16 also is that controlled pressure gas is to tested container 21 and equalizing reservoir 19 inflations or shutoff, wherein solenoid valve 14 is controlled total gas circuit, the gas circuit of tested container 21 is led in solenoid valve 15 control, and solenoid valve 16 then control leads to the gas circuit of equalizing reservoir 19.Tested container 21 is to connect valve 20 usefulness pipelines by tested container to be communicated with solenoid valve 15, and equalizing reservoir 19 then is directly to be communicated with solenoid valve 16 by pipeline.Detection receptacle 21 and equalizing reservoir 19 are arranged after inflation and completely cutting off in parallel connection the between this two pipeline, the differential pressure pick-up 17 of pressure differential between two containers, and for preventing from testing process, to appear at the protection solenoid valve 18 that overload installs additional on the differential pressure pick-up 17.The differential pressure curve of being depicted as with the pressure reduction array of the measured a plurality of pressure reduction numerical value of this programme, as shown in Figure 2.

The scheme of above-mentioned detection device also needs calculation control device shown in Figure 4.This device is by the detection input circuit 22 that comprises amplifier 23 and analog-digital converter 24, contains the microsystem 26 of keyboard input 27, demonstration, printout 28 and storer 25, and is made of the controlling output circuit 29 that relay is formed.The output of the controlled output circuit 29 of the action of solenoid valve control in the pick-up unit, and the data that pressure transducer 7 in the pick-up unit and differential pressure pick-up 17 record are defeated by detection input circuit 22, detecting input circuit 22 amplifies the simulating signal of accepting through amplifier 23, after analog-digital converter 24 becomes digital signal to be defeated by microsystem 26 analog signal conversion, microsystem 26 is calculated with importing 27 calculation procedures of importing and deposit in storer 25 by keyboard according to the detection data of importing, and then result of calculation is passed through demonstration, printout 28 outputs.

The detection of above-mentioned detection device and the calculating of test result all based on detection method provided by the invention, promptly are described in detail detection method provided by the present invention below.It is earlier tested container and equalizing reservoir to be inflated pressurization simultaneously, and will be at this moment as clocking starting time, record inflationtime ta when two container inner pressures reach detected pressures, when the time reaches the pressure time tb of setting, with isolated mutually, sealing between source of the gas and tested container, equalizing reservoir and two containers, the pressure reduction between beginning detection record two containers.Owing to adopt the equalizing reservoir of indefinite capacity, promptly be with testing environment as equalizing reservoir, at this moment the pressure in the equalizing reservoir can be considered a constant, so can the numerical value that pressure transducer is measured think the force value between two containers.And this pressure reduction D (t) can be decomposed into pressure reduction DH (t) that produces by influence of temperature variation and the pressure reduction DL (t) that produces by container leakage.So can have

D (t)=DH (t)+DL (t) ... (1) in the tested container internal pressure during greater than 1.9 times of environmental pressures, the pressure reduction DL (t) that is caused by container leakage then is the linear function of time.

$\mathrm{DL}\left(t\right)=\frac{\mathrm{dDL}\left(t\right)}{\mathrm{dt}}{|}_{t=\mathrm{tb}}(t-\mathrm{tb})\·\·\·\·\·\·\·\·\·\·\·\·\·\left(2\right)$

And the pressure reduction DH (t) that will be caused by temperature variation then has as the step response of inertial element

$\frac{\mathrm{dDL}\left(t\right)}{\mathrm{dt}}{|}_{t>\mathrm{td}}=\frac{\mathrm{dD}\left(T\right)}{\mathrm{dt}}{|}_{t>\mathrm{td}}\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\left(3\right)$

Wherein td is the heat balance time of system.

Adopt the method for numerical differentiation to ask for the heat balance time td of system according to the pressure reduction array that detects thus.Be in the pressure reduction array that detects behind the thermal equilibrium state according to system again and try to achieve formula (3) value, ask for the leakage specific volume speed of tested container then with numerical differentiation

$q=\frac{1}{\mathrm{Po}}\·\frac{\mathrm{dDL}\left(t\right)}{\mathrm{dt}}{|}_{t>\mathrm{td}}\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\left(4\right)$

Wherein Po is the pressure of testing environment.

Institute's pressure measurement difference and time relationship are constituted the pressure reduction function, are constant at tb to the leakage specific volume speed that detects concluding time te then, promptly

$\frac{\mathrm{dDL}\left(t\right)}{\mathrm{dt}}{|}_{t=\mathrm{tb}}=\frac{\mathrm{dDL}\left(t\right)}{\mathrm{dt}}{|}_{t>\mathrm{td}}\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\left(7\right)$

Can get according to formula (2), (4), (7)

DL (t)=qPo (t-tb) ... (8) with DH in the S space as the non-oscillatory second-order response, its expression formula can be reduced to an inertial element

$\frac{A}{1+\mathrm{thS}}\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\left(9\right)$

With a delay link

-(tb-ty)S

E ... (10) combination is that time constant, the ty-tb of inertial element is the time delay of delay link for the amplification coefficient of A inertial element, th in the formula.So can have

$\mathrm{Dt}=A(1-e^{\frac{-(t-\mathrm{ty})}{\mathrm{th}}})\·\·\·\·\·\·\·\·\·\·\·\·\·\left(11\right)$

Can get thus

$A=\mathrm{th}\·\frac{\mathrm{dDH}\left(t\right)}{\mathrm{dt}}{|}_{t=\mathrm{ty}}\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\·\left(12\right)$

Can get by formula (1) and (8)

$\frac{\mathrm{dDH}\left(t\right)}{\mathrm{dt}}{|}_{t=\mathrm{ty}}=\frac{\mathrm{dD}\left(t\right)}{\mathrm{dt}}{|}_{t=\mathrm{ty}}-q\·\mathrm{Po}\·\·\·\·\·\·\·\·\·\·\·\·\left(13\right)$

Can get by formula (11), (12), (13)

$\mathrm{DH}\left(t\right)=\mathrm{th}(\frac{\mathrm{dD}\left(t\right)}{\mathrm{dt}}{|}_{t=\mathrm{ty}}-\mathrm{qPo})\·(1-e^{\frac{-(t-\mathrm{ty})}{\mathrm{th}}})\·\·\·\·\·\·\·\left(14\right)$

Can get the pressure reduction function expression according to the signal of pressure reduction constituent and formula (8), (14) shown in Figure 3

$\mathrm{DH}\left(t\right)=\mathrm{th}(\frac{\mathrm{Dd}\left(t\right)}{\mathrm{Dt}}{|}_{t=\mathrm{ty}}-\mathrm{qPo})\·(1-e^{\frac{-(t-\mathrm{ty})}{\mathrm{th}}})+\mathrm{qPo}(t-\mathrm{ty})+D\left(\mathrm{ty}\right)\·\·\·\·\·\·\·\·\left(15\right)$

Pressure reduction array according to this formula and detection gained adopts non-linear method of least squares to try to achieve the leakage specific volume speed q of container, try to achieve the leakage specific volume speed Q of leak rate again by formula (5), try to achieve leak rate Q by formula (5) again, try to achieve leakage rate VL by formula (6).

Claims (2)

1, a kind of method for detecting leakage of container, it is that tested container and equalizing reservoir are inflated pressurization simultaneously, and will be at this moment as clocking starting time, record inflationtime ta when two container inner pressures reach detected pressures, when the time reaches the pressure time tb of setting, with source of the gas and tested container, isolated between equalizing reservoir and two containers, sealing, pressure reduction D between beginning detection record two containers, it is characterized in that institute's pressure measurement difference and time relationship are constituted pressure reduction function D (t), under the step response of pressure reduction DH that produces by influence of temperature variation as the non-oscillatory second-order system, again with this pressure reduction function D (t) as the be in series step response of system of inertial element and delay link, obtain leakage specific volume speed or leak rate or the leakage rate that the pressure reduction function expression is tried to achieve container with this.

2; a kind of container leakage pick-up unit that utilizes the described method for detecting leakage of container of claim 1 and make; it is by pneumatic supply (10); filtrator (11); pressure is set valve (12); tensimeter (13); solenoid valve (14; 15; 16); and differential pressure pick-up (17); tested container connects valve (20) and equalizing reservoir (19) connects and composes by pipeline; it is characterized in that at the two ends of described differential pressure pick-up (17) simultaneously with pipeline and connect a protection solenoid valve (18); also be provided with in addition by detecting input circuit; the calculation control device that controlling output circuit and microsystem constitute; and the electrical output signal of differential pressure pick-up (17) is connected with the detection input circuit of calculation control device, and the control signal of microcomputer output is by controlling output circuit and solenoid valve (14; 15; 16; 18) doing electric control connects.

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