A kind of fast detecting control method for differential leak detector
Technical field
The present invention relates to differential leak detector technical field, is a kind of fast detecting control method for differential leak detector specifically.
Background technology
As shown in Figure 1, tested end workpiece 11 is for connecing the workpiece of test for the cut-away view of traditional differential leak detector, the charge air cooler of engineering truck diesel engine for example, and charge air cooler internal volume is 2500 milliliters, detected pressures is 350kPa.It is as follows that it detects control procedure:
The first step, after workpiece charge air cooler connects, starts inflation, electric-opening on gas filling valve 4, electric-opening on vent valve 5 closed conditions, standard equalizing valve 8 and tested equalizing valve 9;
Second step, the source of the gas 2 of 400kPa reduces pressure and arrives 350kPa through precise pressure-reducing valve 12, by gas filling valve 4, standard equalizing valve 8 and tested equalizing valve 9, to normal end plug 3 and tested end workpiece 11(, be charge air cooler workpiece) inflation, inflated for 5 seconds after gas filling valve 4 power down close;
The 3rd step, the first equilibrium process, normal end and tested end are by first equilibrium process in 40 seconds, and the displacement that the sidewall of temperature, pressure and measured workpiece expands is in a basic balance and stable;
The 4th step, the second equilibrium process, the time of balance two was 5 seconds, and now standard equalizing valve 8 and 9 power down of tested equalizing valve are closed, and normal end plug 3 and tested end workpiece 11 are divided into two independently air chambers, and object is that the disturbance of closing valve is calmed down;
The 5th step, testing process, the testing process time was 5 seconds.The state of valve is identical with balance two, detects 1 pair of differential pressure transmitter 10 of Time Controller and intends zero processing, has inherited the time dependent slope of differential pressure in balance two processes.The metering of starting from scratch amounts to 5 seconds, the result that obtains differential pressure 5 seconds of detection;
The 6th step, detection time, detection finished rear beginning exhaust, now gas filling valve 4 is closed, vent valve 5, standard equalizing valve 8 and tested equalizing valve 9 are all opened, air-flow from tested end work 11 through sound suppressor 6 discharged to atmosphere, detect to finish.
Wherein, the calculating of leaking differential pressure value Δ PLeak has very important relation with internal volume Vw and t detection time (s) of test leakage rate Q, measured workpiece, and its computing formula is:
From this formula, can find out, when leakage rate Q is zero, both without leaking, leaking differential pressure value Δ PLeak is also zero; Existing leakage when leakage rate is non-vanishing, leaks differential pressure value Δ PLeak non-vanishing, represents that current measured workpiece has leakage.
At current measured workpiece, do not have under leakage situation, in measured workpiece, temperature variation Δ t affects differential pressure value Δ P Δ t and detected pressures P, and its computing formula is:
From this formula, can find out, when in measured workpiece, temperature variation Δ t is non-vanishing, temperature affects differential pressure value Δ P
Δ talso non-vanishing, and along with temperature variation Δ t in measured workpiece increases and increases.
And total differential pressure computing formula is:
P=ΔP
Leak+ΔP
Δt
Δ P
Δ tin non-vanishing situation, what value no matter leaks differential pressure value Δ PLeak is, total differential pressure P, without also non-vanishing, causes false leak, and whether tested reality of work is leaked without actual judge.Therefore, guarantee that the true and reliable precondition of total differential pressure data is, differential pressure value Δ P
Δ tbe zero to be that temperature in measured workpiece is unchanged.
The detection control method that can find in sum traditional differential leak detector has following deficiency:
1, make during the process of continuous charge the temperature in measured workpiece raise, as can be seen from Figure 5 maximum temperature exceeds 1 ℃ than environment temperature, Fig. 3 and Fig. 5 0.01 ℃ of temperature variation within 5 seconds detection times, differential pressure Δ P
Δ tchange 15.4Pa, at this moment just having produced is false leak.And for fear of the generation of false leak, when detecting, need to cool the temperature near ambient temperature range, therefore need to reach balance one process of 40 seconds.Due to balance one process need 40 seconds, whole detection, for up to 60 seconds, made testing cost too high, and detection efficiency is low.
2, as can be seen from Figure 7, if to a measured workpiece continuous coverage 10 times, the differential pressure value Δ P measuring is for the first time 15.4Pa to the maximum, and minimum value is 8.9 Pa, and extreme difference is 6.5 Pa, and this makes the precision and the repeatability that detect become bad.And the differential leak detector of French ATQE company is checked and accepted while using paying, require front 10 data of continuous coverage to disregard, count the 11st to the 20th data and just scrape examination.In actual use, test period and cost have been increased again.
3, on source of the gas, must use a precise pressure-reducing valve 12, make the one-piece construction of differential leak detector become complicated, manual shift reliability variation, has increased high cost, makes the function of pressure unit 7 not maximize performance simultaneously.
How to develop a kind of can express delivery detection test, the detection control method of saving detection experimentation cost has become the technical matters of being badly in need of solution.
Summary of the invention
The object of the invention is that to detect the control procedure time oversize in order to solve in prior art differential leak detector, the defect that detection efficiency is low, provides a kind of fast detecting control method for differential leak detector to solve the problems referred to above.
To achieve these goals, technical scheme of the present invention is as follows:
A kind of fast detecting control method for differential leak detector, differential leak detector comprises controller and the gas filling valve being connected with controller respectively, standard equalizing valve, tested equalizing valve, vent valve, the input end of gas filling valve is connected to source of the gas, the output terminal of gas filling valve by bifurcated pipeline respectively with vent valve, pressure unit, standard equalizing valve is connected with tested equalizing valve, standard equalizing valve is connected with differential pressure transmitter with normal end plug respectively by bifurcated pipeline, tested equalizing valve is connected with differential pressure transmitter with tested end workpiece respectively by bifurcated pipeline, detection control method comprises the following steps:
The first step, adjusts air valve, by electric-opening standard equalizing valve on controller and tested equalizing valve;
Second step, gas replenishment process, inflationtime is 10 seconds, by controller, to gas filling valve, is powered on and applies the pulse voltage of 0.7 second, by controller, to air release, is powered on and applies the pulse voltage of 0.3 second;
The 3rd step, inflation testing process, pressure unit calculates the gaseous tension mean value in gas replenishment process by controller, and after reaching stable mean value, controller, to gas filling valve and air release power-off, prepares to enter balance one process;
The 4th step, balance one process, balance one process time is 10 seconds, guarantees the unlatching of standard equalizing valve and tested equalizing valve by controller;
The 5th step, balance two processes, balance two process times are 5 seconds, by controller power-off, close gas filling valve, standard equalizing valve, tested equalizing valve, vent valve;
The 6th step, testing process, the testing process time is 5 seconds, by closing of controller hold during power off gas filling valve, standard equalizing valve, tested equalizing valve, vent valve, controller is intended zero to differential pressure transmitter and is processed, the result of differential pressure transmitter examination criteria end plug and tested end workpiece differential pressure.
Also comprise exhaust process, the exhaust process time is 5 seconds, by controller, to standard equalizing valve, tested equalizing valve, vent valve, is powered on and opens, and air-flow is discharged.
Described differential leak detector also comprises the sound suppressor being arranged on vent valve, and in described exhaust process, the air-flow of tested end workpiece is discharged from sound suppressor.
beneficial effect
A kind of fast detecting control method for differential leak detector of the present invention, has compared with prior art shortened detection time, has improved detection efficiency, has reduced testing cost.By not changing hardware configuration, only change control method, saved the use of precise pressure-reducing valve, reduced equipment cost.By the time of balance one is shortened, detect and T.T. reduced to 35 seconds by 60 seconds, cost 41.6% saves time.Avoided the gas replenishment process of long-time continuous, the sidewall of measured workpiece be subject to alternative pressure aging after, deformation is little, accuracy of detection improves.When the same workpiece of needs continuous detecting, precision and repeatability improve nearly 10 times than traditional differential leak detector.There is feature simple in structure, easy to use, that reliability is high, efficiency is high.
accompanying drawing explanation
Fig. 1 is the hardware configuration schematic diagram of differential leak detector in prior art
Fig. 2 is the hardware configuration schematic diagram of differential leak detector of the present invention
Fig. 3 is method flow diagram of the present invention
Fig. 4 is the pressure-time curve figure in art methods testing process
Fig. 5 is the temperature-time curve figure in art methods testing process
Fig. 6 is the differential pressure-time plot in art methods testing process
Fig. 7 is the result data of art methods continuous detecting 10 times
Fig. 8 is the pressure-time curve figure in the inventive method testing process
Fig. 9 is the temperature-time curve figure in the inventive method testing process
Figure 10 is the differential pressure-time plot in the inventive method testing process
Figure 11 is the result data of the inventive method continuous detecting 10 times
Wherein, 1-controller, 2-source of the gas, 3-normal end plug, 4-gas filling valve, 5-vent valve, 6-sound suppressor, 7-pressure unit, 8-standard equalizing valve, the tested equalizing valve of 9-, 10-differential pressure transmitter, the tested end workpiece of 11-, 12-precise pressure-reducing valve.
Embodiment
For making that architectural feature of the present invention and the effect reached are had a better understanding and awareness, in order to preferred embodiment and accompanying drawing, coordinate detailed explanation, be described as follows:
As shown in Figures 2 and 3, a kind of fast detecting control method for differential leak detector of the present invention, the hardware configuration of its differential leak detector is to use in prior art, differential leak detector comprises controller 1 and the gas filling valve 4 being connected with controller 1 respectively, standard equalizing valve 8, tested equalizing valve 9, vent valve 5, controller 1 is differential pressure measuring instrument controller, controls the voltage control signal of each valve.The input end of gas filling valve 4 is connected to source of the gas 2, and source of the gas 2 can be 400kPa source of the gas, and the pressure of source of the gas can directly be used at 400~800kPa, the basic demand of source of the gas 2 is met to bleed pressure and at least than detected pressures, exceed 50kPa.At this, saved precise pressure-reducing valve 12, if desired source of the gas 2 has been regulated, only needed to improve or increase inflation pulsed frequency setting and fill-exit pulse width ratio setting.The value that the value of the bound of inflation pulsed frequency setting is 0.25~10Hz, fill-exit the bound of pulse width ratio is 55~95%.If inflation pulsed frequency is 1Hz, filling-exit pulse width ratio is 70%.For extreme situation, if bleed pressure is 800kPa, obtain the detected pressures P of 10kPa, it is 9.5Hz that inflation pulsed frequency can be set, filling-exit pulse width ratio is 55%; For detected pressures P, be less than detected pressures but proximity test pressure very, if bleed pressure is 700kPa, detected pressures is 640 kPa, and it is 1Hz that inflation pulsed frequency can be set, and filling-exit pulse width ratio is 75%.In the situation that the pressure range of source of the gas is large, obtain satisfactory detected pressures, in alternation gas replenishment process, can pass through 7 pairs of charge pressure detection of dynamic of pressure unit, P when its effective mean pressure reaches the detected pressures of setting, controller 1 cuts out gas filling valve 4, close vent valve 5 simultaneously, thereby enter the first equilibrium process.The output terminal of gas filling valve 4 is connected with vent valve 5, pressure unit 7, standard equalizing valve 8 and tested equalizing valve 9 respectively by bifurcated pipeline, standard equalizing valve 8 is connected with differential pressure transmitter 10 with normal end plug 3 respectively by bifurcated pipeline, tested equalizing valve 9 is connected with differential pressure transmitter 10 with tested end workpiece 11 respectively by bifurcated pipeline, and tested end workpiece 11 is for connecing measured workpiece.
Detection control method of the present invention comprises the following steps:
The first step, adjusts air valve, by electric-opening standard equalizing valve 8 and tested equalizing valve 9 on controller 1, guarantees that air pressure can arrive normal end plug 3 and tested end workpiece 11 smoothly.
Second step, gas replenishment process, inflationtime is 10 seconds, powers on to gas filling valve 4 apply the pulse voltage of 0.7 second by controller 1, powers on to air release 4 apply the pulse voltage of 0.3 second by controller 5.Pulse voltage is 0-24V, by apply pulse voltage to gas filling valve 4 and air release 4 simultaneously, replaces in prior art and to gas filling valve 4, applies the air pressure of 5 seconds always.Avoided the gas replenishment process of long-time continuous, the sidewall of measured workpiece be subject to alternative pressure aging after, deformation is little, accuracy of detection improves.As shown in Figure 8, the process of inflation embodies in Fig. 8, in gas replenishment process, the gaseous tension P of measured workpiece inside changes at height is alternation, and the time of inflation is greater than venting, but the mean value of the gaseous tension P of its gas replenishment process increases progressively in time.
The 3rd step, inflation testing process, pressure unit 7 calculates the gaseous tension mean value in gas replenishment process by controller 1, and after reaching stable mean value, controller 1 is given gas filling valve 4 and air release 4 power-off, prepares to enter balance one process.
The 4th step, balance one process, balance one process time is 10 seconds, guarantees the unlatching of standard equalizing valve 8 and tested equalizing valve 9 by controller 1.
The 5th step, balance two processes, balance two process times are 5 seconds, by controller 1 power-off, close gas filling valve 4, standard equalizing valve 8, tested equalizing valve 9, vent valve 5.
As shown in Figure 5, temperature in gas replenishment process in workpiece raises, and exhaust process can be so that the temperature in workpiece reduces, when from 60 seconds, exhaust finished temperature than 20 ℃ low of environment temperatures 10 ℃.From the computing formula of differential pressure value Δ P Δ t, can reach a conclusion: the process of pressure rise is the process heating up, and the process of pressure drop is the process of cooling, and this can produce false leak, workpiece leakage is simultaneously also the process of pressure drop.The object of balance one and balance two processes is exactly in order to make the process of the internal temperature trend environment temperature of workpiece.And in prior art, only have by the workpiece nature temperature fall time of 45 seconds in balance one and balance two processes serious waste Measuring Time.Temperature variation curve as shown in Figure 9, as can be seen from Figure 9, because temperature is alternately to change near environment temperature, so when inflationtime finishes, the internal temperature of measured workpiece has approached environment temperature not to be changed substantially.So in testing process, temperature variation is less than 0.001 ℃, according to differential pressure value computing formula, the differential pressure value Δ P Δ t that now calculates false leak is about 1.5Pa.The pressure of source of the gas can be 400kPa, higher than detected pressures 350 kPa, be that to be subject to alternating pressure maximal value be 400kPa to measured workpiece, the deformation of workpiece also replaces, when balance one process, deformation just tends towards stability quickly like this, i.e. no longer deformation, while entering detection time before workpiece carried out alternately burin-in process.As shown in figure 10, Figure 10 reacts the time dependent amplitude of the differential pressure Δ P Fig. 6 that compares and is much smaller.Again as shown in figure 11, replace the improved differential leak detector of inflation/deflation measured workpiece is carried out to the result that 10 continuous detecting obtain by use, the extreme difference of its data is than superior many before improving.
The 6th step, testing process, the testing process time is 5 seconds, by closing of controller 1 hold during power off gas filling valve 4, standard equalizing valve 8, tested equalizing valve 9, vent valve 5,1 pair of differential pressure transmitter 10 of controller is intended zero and is processed, the result of differential pressure transmitter 10 examination criteria end plugs 3 and tested end workpiece 11 differential pressures, the process of using in this testing process and prior art is similar.
After detection completes, can also comprise the 7th step, exhaust process, the exhaust process time is 5 seconds, by controller 1, powers on and open to standard equalizing valve 8, tested equalizing valve 9, vent valve 5, and air-flow is discharged.In order to reach better result of use, can also comprise the sound suppressor 6 being arranged on vent valve 5, in exhaust process, the air-flow of tested end workpiece 11 is discharged from sound suppressor 6, reduces noise pollution.
Detection control method of the present invention, in five significant process of differential leak detector, be gas replenishment process, balance one process, balance two processes, testing process and exhaust process, the time of five process settings is respectively 10 seconds, 10 seconds, 5 seconds, 5 seconds, add up to 35 seconds, with respect to 60 seconds needed in the art, reduced 25 seconds.The false leak problem causing by the temperature variation Δ t solving in measured workpiece, shorten detection time.Solved the excessive problem of continuous coverage extreme difference, by original 6.5Pa, be reduced to 0.7Pa, precision repeatability has improved approximately order of magnitude, has also saved a precise pressure-reducing valve simultaneously.
More than show and described ultimate principle of the present invention, principal character and advantage of the present invention.The technician of the industry should understand; the present invention is not restricted to the described embodiments; what in above-described embodiment and instructions, describe is principle of the present invention; the present invention also has various changes and modifications without departing from the spirit and scope of the present invention, and these changes and improvements all fall in claimed scope of the present invention.The protection domain that the present invention requires is defined by appending claims and equivalent thereof.