CN1499183A  Calculation method for leakage flow of leakage tester  Google Patents
Calculation method for leakage flow of leakage tester Download PDFInfo
 Publication number
 CN1499183A CN1499183A CNA031526454A CN03152645A CN1499183A CN 1499183 A CN1499183 A CN 1499183A CN A031526454 A CNA031526454 A CN A031526454A CN 03152645 A CN03152645 A CN 03152645A CN 1499183 A CN1499183 A CN 1499183A
 Authority
 CN
 China
 Prior art keywords
 amp
 sb
 lt
 gt
 leakage
 Prior art date
Links
 238000004364 calculation methods Methods 0.000 title claims description 20
 238000004458 analytical methods Methods 0.000 description 1
Abstract
Description
Technical field
The present invention relates to calculate the method for the leakage flow that spills from pneumatic cylinder etc. with leak tester.
Background technology
For the structural detail of the positive displacement of pneumatic cylinder etc., sealing is one of most important index about product property.Utilize differential pressure pickup to measure and have the pressure reduction between the tested container (Work container) of leakage to change the leakage flow that calculates tested container at leak free volumetric standard (benchmark) under the identical original pressure condition.This measuring method has measurement mechanism simple, easy acquisition testing signal, easy to operate a plurality of advantages.Traditional measurement model that utilizes pressure reduction comparison principle measurement leakage air as shown in Figure 1.In Fig. 1, on the pipeline of pneumatic supply with 1 of volumetric standard, on the pipeline of pneumatic supply with 2 of tested containers, dispose cutoff valve V1 and cutoff valve V2 respectively.Differential pressure pickup 3 is configured on the pipeline that is communicated with volumetric standard 1 and tested container 2.
As previously mentioned, volumetric standard 1 is the container that does not have leakage, and tested container 2 is the containers that have minute quantity to leak.When detecting, open cutoff valve V1 and V2, pressurized air flows in two containers simultaneously.Air pressure in two containers reaches closes two cutoff valve V1 and V2 in stable.Because in tested container 2 leakage is arranged, internal pressure descends continuously.So the pressure reduction between two containers increases continuously.Leakage flow is many more, and the variation of pressure reduction is fast more.Use this method, determine the leakage flow of tested container 2 according to computing method described later.
The computing method of traditional leakage flow are that the variation of supposition pressure reduction is linear, have ignored the influence of continuous decline to leaking of interior pressure.Utilize following formula (1) simply must calculate leakage flow.
In addition, according to the practical experience relevant with measuring condition, Measuring Time Δ t is by given in advance.Δ Pt/ Δ t is the variable quantity of pressure reduction.
Although the variation of classic method supposition pressure reduction is linear, is nonlinear actually, exist suitable error between the leakage of measured value and reality.
Summary of the invention
The present invention is first problem with the method (theoretical formula) of seeking the high precision computation leakage flow, is second problem with the error of calculating leakage flow.
At first, the symbol that is used for the present invention's calculating is described.
K _{s}: the coefficient t of differential pressure pickup _{ζ}: the initial detecting time (the unknown during detection)
L: the length V of leak _{e}: the volume of equal value of measured container
M: the quality V of air _{l}: the volume of leakage air
N: the data number V of trial target _{m}: the volume of volumetric standard
P _{a}: atmospheric pressure V _{M0}: the original volume of volumetric standard
P _{m}: the air pressure V in the volumetric standard _{S}: the internal volume of differential pressure pickup
P _{T}: test pressure V _{W}: the volume of measured container
P _{W}: the air pressure V in the measured container _{W0}: the original volume of measured container
Q _{l}: the leakage flow Δ P under the atmospheric pressure _{t}: the variable quantity of the interior pressure reduction of Δ t detection time
R: air constant Δ P: pressure reduction
R: the radius Δ t of leak: Measuring Time
T: air themperature μ: the kinematic viscosity coefficient of air
T: time
Computing method of the present invention are carried out in order to measure the leakage of air flow.Based on the principle of the air flow of leak (supposition aperture is arranged), can obtain containing the theoretical formula of the leakage flow of unknown parameter in periphery.According to the parsing of statistics aspect, the unknown parameter in the mathematical model of pressure reduction, in other words the unknown parameter in the theoretical formula of leakage flow can be calculated out by the test of pressure reduction.Thus, can calculate leakage flow, equally also can extrapolate the error of leakage flow.
The shortcoming of classic method is: the variable quantity of pressure reduction is affected along with the variation of the Measuring Time that begins from initial detecting.In addition, under the actual detection condition, it not is linear that the pressure of measured container changes.Think that in theory mobile leakage air is an isothermal flow.Based on the HagenPoiseuille rule, leakage flow is represented with following theoretical formula.
Exploration also confirms that the position of leak is difficult, and same measurement parameter r and 1 also is difficult, so, calculate the invariant parameter r and 1 in the aforesaid equation in the following method.
The equation of state of the certain air capacity in the container can be expressed with following formula.
PV＝mRT (3)
Think that the air themperature that is spilling is certain.
Behind formula (3) differential, the equation below deriving.
Volumetric standard one side:
Measured container one side
The equation of the pressure reduction between two containers can followingly be represented.
ΔP＝P _{m}P _{w} (6)
The differential equation that produces the volumevariation when leaking is as follows.
After formula (2), can write out the equation of following leakage flow.
Because be small leakage, can carry out following supposition during calculating.
P _{m}=P _{T}, P _{W}=P _{T}, V _{m}=V _{M0}, V _{W}=V _{W0}With abovementioned differential equation from initial detecting time t _{ζ}
Behind the beginning integration, it is as follows to obtain pressure differential deltap P.
Here,
Measure pressure differential deltap P along detection time, be suitable for the principle of LSD (least significant difference LeastSignificant Difference).Parametric t _{ζ}With C be unknown.For easy wushu (a 9) displacement accepted way of doing sth (11).
y＝a+C _{t} (11)
Here,
Utilize the simple regression analysis method, can from formula (14) and formula (15), extrapolate unknown parameter t _{ζ}And C.
In addition, in formula (14), in (15), t _{i}Be n data t _{1}, t _{2}..., t _{i}..., t _{n}In a certain data, y _{i}Be n data y _{1}, y _{2}..., y _{i}..., y _{n}In a certain data.
Based on abovementioned analysis, in actual measurement, the leakage flow of container reduces with the continuous reduction of the internal pressure of measured container., under a certain test pressure, the leakage flow of container is used as the air mass flow that flows to external container in the container usually and considers.So the calculating formula of leakage flow can be write as following form.
In formula (14) substitution formula (16).
Here,
Formula (17) is the real leakage air flow that spills from container under a certain test pressure.Draw from formula (17), the systematic error of this method is determined by formula (19).
The error that is formed by the systematic error delta P of pressure transducer approximately is ± 0.0112MPa.Think the error delta V that the volume measurements of measured container and volumetric standard causes _{W0}With δ V _{M0}Be ± 2 cubic centimetres.δ C is the statistical error of calculation of unknown parameter C, and δ C represents with following formula.
In addition, ζ C is approximately equal to 0.After amounting to abovementioned error, systematic error is approximately 8.2% (P _{T}=0.5MPa).
The computing method of the leakage flow of the described leak tester of claim 1 are the computing method of high precision leakage flow.Can calculate the error of leakage flow with the described computing method of claim 2.
Description of drawings
Fig. 1 is the key diagram that shows the measurement model of traditional leak tester.
Fig. 2 is the key diagram of experimental provision that is used for the air leakage flow of measuring vessel.
Fig. 3 be presented under a certain condition about the experimental data of leakage flow and pressure reduction and the chart of simulation.
Fig. 4 be presented under other conditions about the test data of leakage flow and pressure reduction and the chart of simulation.
Fig. 5 shows the experimental result of the precision be used to confirm computing method of the present invention, Fig. 5 (a) is presented at the test result under the test pressure 0.2MPa, Fig. 5 (b) is presented at the test result under the test pressure 0.5MPa, and Fig. 5 (c) is presented at the experimental result of a certain leak.
Preferred embodiment
Be used for measuring vessel the air leakage flow experimental provision as shown in Figure 2, this is to be used for the device that compares with the result that computing method of the present invention obtain.In Fig. 2, the pressurized air that comes from pneumatic supply is by pressure regulator valve 11 pressure regulation, and the pressurized air after the pressure regulation is measured by tensimeter 12, is input in the A/D converter.In addition, the pressurized air after the pressure regulation may pass through reversal valve 13, and switch valve 15 flows in the volumetric standard 17, also may flow in the measured container 18 by switch valve 16 simultaneously.Differential pressure pickup 19 is configured on the pipeline that is communicated with volumetric standard 17 and measured container 18, and the output signal of differential pressure pickup 19 is imported in the A/D converter 14.Measure the leakage flow that spills from measured container 18 with flowmeter 20, leakage flow is released in the atmosphere by pettiness flow breakout box 21.The output signal of flowmeter 20 is input in the A/D converter 14.
Think that jumbo flowmeter is an inside caliper.Computing machine 22 and A/D converter are used to measure test pressure, pressure reduction between two containers and pettiness leakage flow.The original volume of volumetric standard 17 and tested container 18 is respectively 310.3 cubic centimetres and 376.8 cubic centimetres.
Use experimental provision shown in Figure 2, under same pressure (0.5MPa), test.From experimental data and with its corresponding simulating result, obtain Fig. 3 and Fig. 4.Learn that Simulation result and experimental data based on computing method of the present invention meet very much.
At different leaks, carry out the precision that computing method of the present invention are confirmed in considerable test under the condition of different test pressures.Measurement result as shown in Figure 5.From this table as can be known, computing method of the present invention are than traditional method precision height.
Utilize pressure reduction comparative method for measuring leakage of air flow, proved that it is nonlinear that pressure reduction changes.Thus, traditional as can be known computing method are not enough as the measuring method accuracy of air leakage flow.
Adopt actual pettiness flow equation formula and statistical method to propose to be used to measure the computing method of the present invention of air leakage flow.Between the leakage flow of computing method of the present invention and reality, more unanimity is arranged.Compare with traditional computing method, improved the measuring accuracy of air leakage flow.
Claims (2)
Priority Applications (2)
Application Number  Priority Date  Filing Date  Title 

JP361461/2002  20021111  
JP2002361461A JP4022752B2 (en)  20021111  20021111  Leakage flow measurement method 
Publications (1)
Publication Number  Publication Date 

CN1499183A true CN1499183A (en)  20040526 
Family
ID=32809733
Family Applications (1)
Application Number  Title  Priority Date  Filing Date 

CNA031526454A CN1499183A (en)  20021111  20030804  Calculation method for leakage flow of leakage tester 
Country Status (2)
Country  Link 

JP (1)  JP4022752B2 (en) 
CN (1)  CN1499183A (en) 
Cited By (9)
Publication number  Priority date  Publication date  Assignee  Title 

CN102147316A (en) *  20110129  20110810  平湖美嘉保温容器工业有限公司  Tightness tester 
CN102778338A (en) *  20120726  20121114  黑龙江建龙钢铁有限公司  Method for measuring leakage of fractionating column through pressure meter 
CN104215392A (en) *  20140912  20141217  天津博益气动股份有限公司  Device and method for detecting sensing coefficient of differential pressure sensor 
CN104865024A (en) *  20150616  20150826  中信戴卡股份有限公司  Device and method for measuring airtightness of aluminium alloy hub or tire 
CN105282674A (en) *  20140626  20160127  致伸科技股份有限公司  Sealed type loudspeaker air leakage testing system and method 
CN106441743A (en) *  20161012  20170222  神华集团有限责任公司  Measuring device of evaporation pool leakage and measuring method of the evaporation pool leakage 
CN107677429A (en) *  20170818  20180209  湖南军成科技有限公司  A kind of airtightness detection device and its detection method 
CN108534964A (en) *  20180423  20180914  苏州阡晨金属包装设备有限公司  A kind of metal top pop tank airtightness detection device 
CN108561757A (en) *  20180319  20180921  创尔特热能科技(中山)有限公司  A kind of parameter setting method of gas leak detection apparatus 
Families Citing this family (3)
Publication number  Priority date  Publication date  Assignee  Title 

CN101160518B (en) *  20050202  20100804  膜康公司  Instrument and method for detecting and reporting the size of leaks in hermetically sealed packaging 
JP4923957B2 (en) *  20061030  20120425  アイシン精機株式会社  Leak inspection device 
CN105806570A (en) *  20160516  20160727  沈阳紫微机电设备有限公司  Gas leakchecking detecting device 

2002
 20021111 JP JP2002361461A patent/JP4022752B2/en active Active

2003
 20030804 CN CNA031526454A patent/CN1499183A/en not_active Application Discontinuation
Cited By (10)
Publication number  Priority date  Publication date  Assignee  Title 

CN102147316A (en) *  20110129  20110810  平湖美嘉保温容器工业有限公司  Tightness tester 
CN102778338A (en) *  20120726  20121114  黑龙江建龙钢铁有限公司  Method for measuring leakage of fractionating column through pressure meter 
CN105282674B (en) *  20140626  20190315  惠州超声音响有限公司  Sealed loudspeaker gas leakage test macro and method 
CN105282674A (en) *  20140626  20160127  致伸科技股份有限公司  Sealed type loudspeaker air leakage testing system and method 
CN104215392A (en) *  20140912  20141217  天津博益气动股份有限公司  Device and method for detecting sensing coefficient of differential pressure sensor 
CN104865024A (en) *  20150616  20150826  中信戴卡股份有限公司  Device and method for measuring airtightness of aluminium alloy hub or tire 
CN106441743A (en) *  20161012  20170222  神华集团有限责任公司  Measuring device of evaporation pool leakage and measuring method of the evaporation pool leakage 
CN107677429A (en) *  20170818  20180209  湖南军成科技有限公司  A kind of airtightness detection device and its detection method 
CN108561757A (en) *  20180319  20180921  创尔特热能科技(中山)有限公司  A kind of parameter setting method of gas leak detection apparatus 
CN108534964A (en) *  20180423  20180914  苏州阡晨金属包装设备有限公司  A kind of metal top pop tank airtightness detection device 
Also Published As
Publication number  Publication date 

JP4022752B2 (en)  20071219 
JP2004163378A (en)  20040610 
Similar Documents
Publication  Publication Date  Title 

CN101069069B (en)  Method and apparatus for determining flow pressure using density information  
US9863838B2 (en)  Air tightness detection device for aluminum alloy wheel hub and method for detecting air tightness of wheel hub  
CN101451893B (en)  Test system and test method for hydraulic cylinder with loading friction force characteristic  
Corey  Air permeability  
CN102221514B (en)  Joint testing device and method of rheological property of polymer solution and relative permeability of core  
CN102607636B (en)  Comparison type calibration method for dynamic measurement system  
CN204649538U (en)  Rock three axle acoustic emission experiment device under a kind of confined pressure, hole press strip part  
CN103033442A (en)  Gas adsorption and desorption test apparatus  
CN101539502B (en)  Method for measuring liquiddrop contact angle on solid surface and device thereof  
CN107270980B (en)  The measurement method of gasliquid twophase annular flow thickness of liquid film and flow in a kind of vertical tube  
CN1995940B (en)  Sealing performance detection method by using vacuum balancing method  
CN101470016B (en)  Apparatus for measuring volume by builtin method  
GB1583393A (en)  Method and apparatus for measuring volume and density of fluids in a drilling fluid system  
CN205138940U (en)  Test coal body gas adsorbs desorption heat effect experimental system  
CN103033421B (en)  Bulging experiment device for directly testing mechanical property of pipe  
CN103234860B (en)  Carbon dioxide adsorption isotherm precision testing method  
CN203672759U (en)  Osmosis device for crushed rock triaxial seepage test  
CN103411869A (en)  Negative pressure osmosis test device  
CN104697913B (en)  Tight sand gas testing permeability device and method of testing  
CN2700883Y (en)  Noncontact high temperature and high pressure intelligent expanding instrument  
CN203981234U (en)  Pneumatic process volume measurement device  
CN201242522Y (en)  Apparatus for measuring lowleakage and ultralow leakage rock core coke porosity  
CN202033067U (en)  Solid volume measurement instrument  
CN106017350A (en)  Machinevisionbased rapid detection device and detection method for medium and small module gears  
Lohrenz et al.  An experimentally verified theoretical study of the falling cylinder viscometer 
Legal Events
Date  Code  Title  Description 

PB01  Publication  
C06  Publication  
SE01  Entry into force of request for substantive examination  
C10  Entry into substantive examination  
RJ01  Rejection of invention patent application after publication  
C12  Rejection of a patent application after its publication 