A kind of quick detection control method for differential leak detector
Technical field
The present invention relates to differential leak detector technical field, specifically a kind of quick detection control method for differential leak detector.
Background technology
As shown in Figure 1, tested end workpiece 11 is for connecing the workpiece of test, and the such as charge air cooler of engineering truck diesel engine, charge air cooler internal volume is 2500 milliliters, and detected pressures is 350kPa for the cut-away view of traditional differential leak detector.Its detection control process is as follows:
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 condition, standard equilibration valve 8 and tested equalizing valve 9;
Second step, the source of the gas 2 of 400kPa reduces pressure through precise pressure-reducing valve 12 and arrives 350kPa, by gas filling valve 4, standard equilibration valve 8 and tested equalizing valve 9 to normal end plug 3 and tested end workpiece 11(and charge air cooler workpiece) inflation, after inflating for 5 seconds, gas filling valve 4 power down is closed;
3rd step, the first equilibrium process, normal end and tested end pass through 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;
4th step, the second equilibrium process, the time of balance two was 5 seconds, and now standard equilibration valve 8 and tested equalizing valve 9 power down is 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 pass valve is calmed down;
5th step, testing process, the testing process time was 5 seconds.The state of valve is identical with balance two, detects Time Controller 1 pair of differential pressure transmitter 10 and carries out plan zero process, inherit the time dependent slope of differential pressure in balance two process.Metering of starting from scratch amounted to for 5 seconds, obtained the result of differential pressure 5 seconds of detection;
6th step, detection time detect terminate after start exhaust, now gas filling valve 4 is closed, and vent valve 5, standard equilibration valve 8 and tested equalizing valve 9 are all opened, air-flow from tested end work 11 through sound suppressor 6 discharged to air, detect terminate.
Wherein, leak the count and check leakage rate Q of differential pressure value Δ PLeak, the internal volume Vw of measured workpiece and have very important relation t detection time (s), its computing formula is:
As can be seen from this formula, both No leakage when leakage rate Q is zero, 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.
Under current measured workpiece does not have 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:
As can be seen from this formula, when in measured workpiece, temperature variation Δ t is non-vanishing, temperature affects differential pressure value Δ P
Δ talso non-vanishing, and increase along with temperature variation Δ t in measured workpiece and increase.
And total differential pressure computing formula is:
P=ΔP
Leak+ΔP
Δt
Then Δ P
Δ twhen non-vanishing, whether what value no matter leaks differential pressure value Δ PLeak is, total differential pressure P then without also non-vanishing, causes false leak, leak without actual judge tested reality of work.Therefore, ensure that the true and reliable precondition of total differential pressure data is, differential pressure value Δ P
Δ tbe that zero temperature that is in measured workpiece is unchanged.
Can find that the detection control method of traditional differential leak detector has following deficiency in sum:
During the process of 1, continuous charge, the temperature in measured workpiece is raised, as can be seen from Figure 5 maximum temperature exceeds 1 DEG C than environment temperature, Fig. 3 and Fig. 5 be temperature variation 0.01 DEG C within 5 seconds detection times, differential pressure Δ P
Δ tchange 15.4Pa, at this moment just creating is false leak.And in order to avoid the generation of false leak, then needing when detecting to cool the temperature near ambient temperature range, therefore needing balance one process reaching 40 seconds.Owing to balancing a process need 40 seconds, whole detection was for up to 60 seconds, and make testing cost too high, 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 that first time measures is 15.4Pa to the maximum, and minimum value is 8.9Pa, and extreme difference is 6.5Pa, and this makes the precision detected become bad with repeatability.And the differential leak detector of French ATQE company is when paying examination and using, requires front 10 data of continuous coverage to disregard, count the 11 to the 20 data and just scrape examination.In actual use, test period and cost is turn increased.
3, must use a precise pressure-reducing valve 12 on source of the gas, make the one-piece construction of differential leak detector become complicated, manual shift less reliable, adds high cost, makes the function of pressure unit 7 not maximize performance simultaneously.
How developing one can express delivery detection experiment, and the detection control method of saving detection experiment cost has become the technical matters being badly in need of solving.
Summary of the invention
The object of the invention is to solve differential leak detector detection control process time in prior art oversize, the defect that detection efficiency is low, providing a kind of quick detection 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 quick detection control method for differential leak detector, differential leak detector comprises controller and the gas filling valve be connected with controller respectively, standard equilibration 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 equilibration valve is connected with tested equalizing valve, standard equilibration 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, adjustment air valve, by electric-opening standard equilibration valve on controller and tested equalizing valve;
Second step, gas replenishment process, inflationtime is 10 seconds, to be powered on the applying pulse voltage of 0.7 second to gas filling valve by controller, to be powered on the applying pulse voltage of 0.3 second by controller discharge air valve;
3rd step, inflation testing process, pressure unit calculates the gaseous tension mean value in gas replenishment process by controller, after stable mean value to be achieved, controller is to gas filling valve and vent valve power-off, prepares to enter balance one process;
4th step, balances a process, and balancing a process time is 10 seconds, is ensured the unlatching of standard equilibration valve and tested equalizing valve by controller;
5th step, balances two processes, and balancing two process times is 5 seconds, closes gas filling valve, standard equilibration valve, tested equalizing valve, vent valve by controller power-off;
6th step, testing process, the testing process time is 5 seconds, is kept the closedown of gas filling valve, standard equilibration valve, tested equalizing valve, vent valve by controller power-off, controller carries out plan zero process to differential pressure transmitter, 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, is powered on and opens, discharged by air-flow by controller to standard equilibration valve, tested equalizing valve, vent valve.
Described differential leak detector also comprises the sound suppressor be 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 quick detection control method for differential leak detector of the present invention, compared with prior art shortens detection time, improves detection efficiency, reduce testing cost.By not changing hardware configuration, only changing control method, saving the use of precise pressure-reducing valve, reducing equipment cost.By being shortened the time of balance one, detect and T.T. reduced to 35 seconds by 60 seconds, save time cost 41.6%.Avoid 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 pressure leak locator.Have the advantages that structure is simple, easy to use, 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 equilibration 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 to have a better understanding and awareness architectural feature of the present invention and effect of reaching, coordinating detailed description in order to preferred embodiment and accompanying drawing, being described as follows:
As shown in Figures 2 and 3, a kind of quick detection control method for differential leak detector of the present invention, the hardware configuration of its differential leak detector is for using in prior art, differential leak detector comprises controller 1 and the gas filling valve 4, standard equilibration valve 8, tested equalizing valve 9, the vent valve 5 that are connected with controller 1 respectively, 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 use at 400 ~ 800kPa, meets bleed pressure at least exceed 50kPa than detected pressures to the basic demand of source of the gas 2.Eliminate precise pressure-reducing valve 12 at this, if desired source of the gas 2 is regulated, only need improvement or increase inflation pulsed frequency to arrange and fill-exit pulse width ratio and arrange.The value of bound that inflation pulsed frequency is arranged is 0.25 ~ 10Hz, fill-exit the value of the bound of pulse width ratio is 55 ~ 95%.If inflation pulsed frequency is 1Hz, filling-exit pulse width ratio is then 70%.For extreme situation, if bleed pressure is 800kPa, obtain the detected pressures P of 10kPa, can arrange inflation pulsed frequency is 9.5Hz, and filling-exit pulse width ratio is 55%; Be less than detected pressures for detected pressures P but very proximity test pressure, if bleed pressure is 700kPa, detected pressures is 640kPa, and can arrange inflation pulsed frequency is 1Hz, and filling-exit pulse width ratio is 75%.When the pressure range of source of the gas is large, obtain satisfactory detected pressures, pressure unit 7 pairs of charge pressure detection of dynamic can be passed through in alternation gas replenishment process, 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, thus enter the first equilibrium process.The output terminal of gas filling valve 4 is connected with tested equalizing valve 9 with vent valve 5, pressure unit 7, standard equilibration valve 8 respectively by bifurcated pipeline, standard equilibration 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, adjustment air valve, by electric-opening standard equilibration valve 8 and tested equalizing valve 9 on controller 1, ensures that air pressure can arrive normal end plug 3 and tested end workpiece 11 smoothly.
Second step, gas replenishment process, inflationtime is 10 seconds, to power on the applying pulse voltage of 0.7 second to gas filling valve 4 by controller 1, to be powered on the applying pulse voltage of 0.3 second by controller 1 discharge air valve 5.Pulse voltage is 0-24V, by applying pulse voltage to gas filling valve 4 and vent valve 5 simultaneously, replaces in prior art the air pressure always applying 5 seconds to gas filling valve 4.Avoid 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, and in gas replenishment process, namely the gaseous tension P of measured workpiece inside is alternation in height change, and 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.
3rd step, inflation testing process, pressure unit 7 calculates the gaseous tension mean value in gas replenishment process by controller 1, after stable mean value to be achieved, controller 1 gives gas filling valve 4 and vent valve 5 power-off, prepares to enter balance one process.
4th step, balances a process, and balancing a process time is 10 seconds, is ensured the unlatching of standard equilibration valve 8 and tested equalizing valve 9 by controller 1.
5th step, balances two processes, and balancing two process times is 5 seconds, closes gas filling valve 4, standard equilibration valve 8, tested equalizing valve 9, vent valve 5 by controller 1 power-off.
As shown in Figure 5, the temperature in gas replenishment process in workpiece raises, and exhaust process can make the temperature in workpiece reduce, and at the end of being vented from 60 seconds, temperature is lower than environment temperature 20 DEG C 10 DEG C.Can reach a conclusion from the computing formula of differential pressure value Δ P Δ t: the process of pressure increase is the process heated up, the process of pressure drop is the process of cooling, and this can produce false leak, and workpiece leakage simultaneously is also the process of pressure drop.The object of balance one and balance two processes is exactly the process of the internal temperature trend environment temperature in order to make workpiece.And only have the workpiece Temperature fall time by balancing in one and balance two processes 45 seconds in prior art, serious waste Measuring Time.Temperature variation curve as shown in Figure 9, as can be seen from Figure 9, because temperature is that so at the end of inflationtime, the internal temperature of measured workpiece does not change substantially close to environment temperature near ambient temperature alternately change.So in testing process, temperature variation is less than 0.001 DEG C, and according to differential pressure value computing formula, the differential pressure value Δ P Δ t now calculating false leak is about 1.5Pa.The pressure of source of the gas can be 400kPa, higher than detected pressures 350kPa, namely measured workpiece is subject to alternating pressure maximal value is 400kPa, the deformation of workpiece also replaces, when balance one process, deformation just tends towards stability quickly like this, i.e. no longer deformation, when entering detection time, front workpiece has 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, carry out the result that 10 continuous detecting obtain by the differential leak detector that improves with alternately inflation/deflation to measured workpiece, the extreme difference of its data is front superior more than improving.
6th step, testing process, the testing process time is 5 seconds, the closedown of gas filling valve 4, standard equilibration valve 8, tested equalizing valve 9, vent valve 5 is kept by controller 1 power-off, controller 1 pair of differential pressure transmitter 10 carries out plan zero process, the result of differential pressure transmitter 10 examination criteria end plug 3 and tested end workpiece 11 differential pressure, the process used 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, powers on and opens to standard equilibration valve 8, tested equalizing valve 9, vent valve 5, discharged by air-flow by controller 1.In order to reach better result of use, can also comprise the sound suppressor 6 be 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, namely gas replenishment process, balance a process, balance two processes, testing process and exhaust process, the time of five process settings is 10 seconds, 10 seconds, 5 seconds, 5 seconds respectively, add up to 35 seconds, decrease 25 seconds relative to 60 seconds needed in the art.The false leak problem caused by the temperature variation Δ t solved in measured workpiece, shorten detection time.Solve the problem that continuous coverage extreme difference is excessive, be reduced to 0.7Pa by original 6.5Pa, precision repeatability improves about order of magnitude, also saves a precise pressure-reducing valve simultaneously.
More than show and describe 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; the just principle of the present invention described in above-described embodiment and instructions; 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 of application claims is defined by appending claims and equivalent thereof.