CN113567071A - Rapid vacuum leak detection system and method - Google Patents
Rapid vacuum leak detection system and method Download PDFInfo
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- CN113567071A CN113567071A CN202110842077.3A CN202110842077A CN113567071A CN 113567071 A CN113567071 A CN 113567071A CN 202110842077 A CN202110842077 A CN 202110842077A CN 113567071 A CN113567071 A CN 113567071A
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- 238000001514 detection method Methods 0.000 title claims abstract description 98
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- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/32—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators
- G01M3/3236—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers
- G01M3/3263—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for containers, e.g. radiators by monitoring the interior space of the containers using a differential pressure detector
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Abstract
The invention discloses a rapid vacuum leak detection system, which comprises a vacuum pipeline, wherein one end of the vacuum pipeline is connected with a vacuum pump, the vacuum pipeline is sequentially provided with an electromagnetic valve YV1 for controlling the on-off of the vacuum pipeline and a pressure sensor for detecting the pressure of the vacuum pipeline, the other end of the vacuum pipeline is connected with an electromagnetic valve YV2 and an electromagnetic valve YV3 in parallel, the vacuum pipeline where the electromagnetic valve YV2 is located is sequentially communicated with a first cavity body, an electromagnetic valve YV4 and a detection cavity body until the vacuum pipeline is communicated to the positive phase of a differential pressure sensor; and the vacuum pipeline where the electromagnetic valve YV3 is located is sequentially communicated with the second cavity, the electromagnetic valve YV5 and the reference cavity until the vacuum pipeline is communicated to the negative phase of the differential pressure sensor. The invention also provides a rapid vacuum leak detection method, which can detect the condition that the content of the detected package is gas, liquid and gas-liquid mixture within a detection range; but also can be applied to the on-line detection of the whole product with the vacuum system repeatedly opened and closed, and can greatly shorten the detection time.
Description
Technical Field
The invention relates to the technical field of leak tightness detection, in particular to a rapid vacuum leak detection system and a rapid vacuum leak detection method.
Background
In the process flow of food and medicine production, the tightness detection is an essential quality inspection link. At present, the sealing performance detection in the market is mainly lamp detection, high-voltage discharge detection and vacuum attenuation detection methods. The high-voltage discharge detection has higher requirements on the physical properties of samples, mainly the samples are sealed and packaged to be non-conductive, and the contained solution is conductive. Therefore, the vacuum attenuation method is mostly adopted to test samples which are not inspected by a lamp and have non-transparent packages and the conductivity which is not qualified for high-voltage discharge inspection. Although the vacuum decay method is basically suitable for detecting all sealed products and cannot be replaced by certain specific packaging structures and materials, the vacuum decay method has long detection time and high requirement on the tightness of instruments. So, the vacuum attenuation method is rarely adopted to carry out the sealing detection of the whole product so far, and the sampling detection is mostly selected.
The difficulty of the vacuum attenuation method for detecting the whole product is mainly divided into two points, one is that the vacuum attenuation method has long detection time. The method is generally divided into three stages, wherein the first stage is used for judging when the detection chamber is vacuumized, and if the preset value cannot be reached, the judgment is that the leakage is large; the second stage is a pressure maintaining stage, and if the reference vacuum degree can not be reached within the preset time, the middle leakage stage is realized; the third stage is a test stage, and if the actual vacuum decay rate value is greater than the reference value, the leak is small. The method has the advantages that the upper limit value of the tested micropores is smaller than that of other methods, but the testing stages are multiple, and the testing time is long and is always subject to industrial defects. And the second is high requirement on the tightness of the detection system. In fact, the requirement for the back pressure, that is, the sealing performance of the detection chamber, is extremely strict, and experiments show that the signal-to-noise ratio of the detection chamber with a high sealing performance is close to 1 when the detection chamber with a diameter of 1 micron is used, so that the reliability of data is greatly reduced. The whole product test needs repeated vacuum pumping and pressure relief of the vacuum chamber, and the requirement on the sealing property of small leakage detection is basically difficult to achieve. More importantly, when the sealed package containing liquid is detected, liquid leakage caused by unqualified products can remain in the vacuum detection chamber, serious influence can be caused on the repeatability of the vacuum degree of the cavity, and the test can not be continued basically. And the cavity is cleaned and dried, which takes a lot of time. I.e. drying times of more than 1 minute have a serious impact on the efficiency of the detection system, relative to detection times of the order of 10 seconds.
Disclosure of Invention
In order to solve the problems, the method judges whether the detected sample leaks or not by judging whether the water hammer effect is generated or not at the early stage of vacuumizing from the phenomenon of water hammer which often occurs in a liquid pipeline. The method has low requirements on the repeatability of the vacuum degree of the cavity and the sealing performance of the sealed cavity, and can well solve the problem of whole-product detection of the vacuum detection method. The phenomenon of water hammer is mainly caused when the pipeline valve is quickly opened and closed, and an energy shock wave is generated, so that the pipeline and the valve are very destructive. The principle is that when the valve is closed suddenly, the liquid near the valve end is stopped suddenly, and the liquid at the far end has inertia and certain compressibility, so that the sudden change of the flow rate causes an over-high pressure impact in the pipeline, and the force generated by the impact wave back and forth is like a hammer, so that the pipeline is called a water hammer. The rapid closing of the valve creates a positive pressure on the pipe wall and the valve, called positive water hammer. Similarly, when the valve is opened rapidly, negative pressure is generated on the pipe wall, which is called negative water hammer. This "water hammer" phenomenon can also occur when the sealed package leaks, which is inside an evacuated vacuum chamber, and if there is a leak, when the pressure difference inside and outside the leak hole is large enough, the leak path becomes suddenly open. A shock wave of negative pressure is generated which can be captured by the patented device to determine the tightness of the sealed package. The method for detecting the sealing performance of the sealed package by using the water hammer principle belongs to the first example in the field of vacuum leak detection.
The invention aims to provide a rapid vacuum leak detection system. The technical scheme for realizing the purpose of the invention is as follows: a quick vacuum leak detection system comprises a vacuum pipeline, wherein one end of the vacuum pipeline is connected with a vacuum pump, the vacuum pipeline is sequentially provided with a solenoid valve YV1 for controlling the on-off of the vacuum pipeline and a pressure sensor for detecting the pressure of the vacuum pipeline, the other end of the vacuum pipeline is provided with a solenoid valve YV2 and a solenoid valve YV3 in parallel, the quick vacuum leak detection system further comprises a first cavity, a second cavity, a detection cavity internally provided with a sample to be detected, a reference cavity internally provided with a reference entity and a differential pressure sensor, and the vacuum pipeline where the solenoid valve YV2 is located is sequentially communicated with the first cavity, the solenoid valve YV4 and the detection cavity until the vacuum pipeline is communicated with the normal phase of the differential pressure sensor; and the vacuum pipeline where the electromagnetic valve YV3 is located is sequentially communicated with the second cavity, the electromagnetic valve YV5 and the reference cavity until the vacuum pipeline is communicated to the negative phase of the differential pressure sensor.
Preferably, the volume of the reference entity is larger than the volume of the sample to be detected.
The invention also provides a leak detection method for leak detection by adopting the rapid vacuum leak detection system, which comprises the following steps:
the method comprises the following steps: opening an electromagnetic valve YV1, an electromagnetic valve YV2 and an electromagnetic valve YV3, closing an electromagnetic valve YV4 and an electromagnetic valve YV5, opening a vacuum pump, closing an electromagnetic valve YV1 when a pressure sensor reaches a set threshold value, and closing the vacuum pump in a delayed manner;
step two: after the pressure values of the first cavity and the second cavity are equal and stable for a certain time, closing the electromagnetic valve YV2 and the electromagnetic valve YV 3; if the pressure sensor can not be maintained stable, the system is closed to wait for the instrument to be checked, the first step is executed after the instrument is checked, and if the pressure sensor is maintained stable, the next step is executed;
step three: and simultaneously opening the electromagnetic valve YV4 and the electromagnetic valve YV5, starting to record data of the differential pressure sensor, wherein the data of the differential pressure sensor is a current value, and then performing leak detection judgment according to the current value.
Preferably, the current value leak detection determination method includes:
step A: judging that the signal current value of the differential pressure sensor reaches a preset value within preset time, and judging that the signal current value of the differential pressure sensor leaks;
and B: if the signal current value of the differential pressure sensor does not reach the preset value within the preset time, entering the next step to execute the next judgment mode;
and step C, entering a pressure acceleration judging mode, and utilizing discrete data to carry out interpolation judgment to judge whether leakage exists.
Preferably, the specific method for performing interpolation judgment by using discrete data is as follows:
step a: deriving current value data of the differential pressure sensor according to sampling frequency to form equidistant discrete data;
step b: the first derivative and the second derivative are obtained by adopting a difference method on the equidistant discrete data,
step c: judging the first-order derivative, wherein air leakage is judged when the first-order derivative is smaller than a preset value 1, and the radius of an air leakage hole is large; if the air leakage is larger than the preset value 1, entering a second derivative judgment stage, if the air leakage is smaller than the preset value 2, judging that air leakage exists, and enabling the radius of the air leakage hole to be small; a second derivative greater than a preset value of 2 is a good seal.
Preferably, the extracted data are data after the solenoid valve YV4 and the solenoid valve YV5 are opened for a certain preset time.
Preferably, the electromagnetic valve YV4 and the electromagnetic valve YV5 are three-way electromagnetic valves, the electromagnetic valve YV4 and the electromagnetic valve YV5 are communicated with a vacuum pipeline after detection is finished, pressure relief is opened, and pressure relief is closed and pipeline connection of the electromagnetic valve YV4 and the electromagnetic valve YV5 is disconnected after pressure reaches a preset value.
Preferably, the value of the differential pressure sensor is detected within a preset time, and when the value exceeds a preset value, the detected value is used as a 'compensation value' to compensate the preset value in the step A.
By adopting the technical scheme, the invention has the following beneficial effects: (1) the method realizes the tightness detection of the vacuum system by using the 'water hammer' effect, has no great requirement on the repeatability of the background vacuum degree, has no high requirement on the tightness of the vacuum system, and is very suitable for the online detection of all products with the vacuum system repeatedly opened and closed.
(2) The method can realize rapid detection, the middle leakage which cannot be judged in the original vacuum leakage detecting and pressure maintaining stage can be judged in the vacuum pumping stage in the prior art, and the judgment time is greatly shortened.
(3) The method has the advantages that the detectable range covers the condition that the content of the detected package is gas, liquid and gas-liquid mixture, the method has better detection effect on the sealed sample containing liquid, and the residual liquid is not required to be cleaned; experimental data show that the data change is more obvious when the liquid leaks due to the water hammer effect; the reason is that the liquid has a greater inertia relative to the gas and the shock waves generated are more pronounced.
(4) The invention is provided with the reference cavity, so that the disturbance influence of the shock wave on the pressure field can be eliminated, and the universality test can be carried out.
(5) According to the invention, the compensation value of the detection data is added into the preset value, so that the influence of high air pressure caused by liquid volatilization can be eliminated; the liquid that probably remains in can solving prior art because contaminated detection cavity seals the detection cavity again after the transient pressure release, can lead to the liquid in the detection cavity to volatilize, and at this moment, the pressure that detects the cavity just is greater than atmospheric pressure to cause differential pressure sensor's a technical problem of erroneous judgement.
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In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which
FIG. 1 is a schematic view of an evacuation system according to the present invention;
FIG. 2 is a graph showing the current change with time of a differential pressure sensor after a valve is opened when no sample leakage is detected;
FIG. 3 is a graph showing the difference in data between intact and deflated samples.
Detailed Description
Example one
Fig. 1 is a schematic diagram of a rapid vacuum-pumping system, and YV represents an electromagnetic valve for controlling the opening and closing of a vacuum pipe 8. A sample 51 to be detected is placed in the detection cavity 5, and a reference entity 61 with a volume slightly larger than that of the sample to be detected is placed in the reference cavity 6. It should be noted that, because the volume of the sample to be detected inevitably has a small difference, and the differential pressure sensor is very sensitive, when the sample to be detected is not leaked and the volume is larger than the reference entity, the negative phase pressure of the differential pressure sensor is larger than the positive phase pressure, and no numerical value is displayed, and the detection and judgment cannot be performed, so the volume of the reference entity should be larger than the volume of the sample to be detected. The straight line is a vacuum pipeline. The vacuum pump 1 is used for pumping the pipeline gas to reach a certain vacuum degree, and the electromagnetic valve YV1 is used for controlling the opening and closing of the main pipeline of the vacuum pipeline. A quick vacuum leak detection system comprises a vacuum pipeline 8, one end of the vacuum pipeline is connected with a vacuum pump 1, the vacuum pipeline is sequentially provided with a solenoid valve YV1 for controlling the on-off of the vacuum pipeline and a pressure sensor 2 for detecting the pressure of the vacuum pipeline, the other end of the vacuum pipeline is provided with a solenoid valve YV2 and a solenoid valve YV3 in parallel, the quick vacuum leak detection system further comprises a first cavity body 3, a second cavity body 4, a detection cavity body 5 with a sample 51 to be detected arranged inside, a reference cavity body 61 with a reference entity 61 arranged inside and a differential pressure sensor 7, the vacuum pipeline with the solenoid valve YV2 is sequentially communicated with the first cavity body, the solenoid valve YV4 and the detection cavity body until the normal phase of the differential pressure sensor is communicated; and the vacuum pipeline where the electromagnetic valve YV3 is located is sequentially communicated with the second cavity, the electromagnetic valve YV5 and the reference cavity until the vacuum pipeline is communicated to the negative phase of the differential pressure sensor.
The invention also provides a leak detection method for leak detection by adopting the rapid vacuum leak detection system, which comprises the following steps:
the method comprises the following steps: opening an electromagnetic valve YV1, an electromagnetic valve YV2 and an electromagnetic valve YV3, closing an electromagnetic valve YV4 and an electromagnetic valve YV5, opening a vacuum pump, closing an electromagnetic valve YV1 when a pressure sensor reaches a set threshold value, and closing the vacuum pump in a delayed manner;
step two: after the pressure values of the first cavity and the second cavity are equal and stable for a certain time, closing the electromagnetic valve YV2 and the electromagnetic valve YV 3; if the pressure sensor can not be maintained stable, the system is closed to wait for the instrument to be checked, the first step is executed after the instrument is checked, and if the pressure sensor is maintained stable, the next step is executed;
step three: and simultaneously opening the electromagnetic valve YV4 and the electromagnetic valve YV5, starting to record data of the differential pressure sensor, wherein the data of the differential pressure sensor is a current value, and then performing leak detection judgment according to the current value.
Preferably, the current value leak detection determination method includes:
step A: judging that the signal current value of the differential pressure sensor reaches a preset value within preset time, and judging that the signal current value of the differential pressure sensor leaks;
and B: if the signal current value of the differential pressure sensor does not reach the preset value within the preset time, entering the next step to execute the next judgment mode;
and step C, entering a pressure acceleration judging mode, and utilizing discrete data to carry out interpolation judgment to judge whether leakage exists.
Preferably, the specific method for performing interpolation judgment by using discrete data is as follows:
step a: deriving current value data of the differential pressure sensor according to sampling frequency to form equidistant discrete data;
step b: the first derivative and the second derivative are obtained by adopting a difference method on the equidistant discrete data,
step c: judging the first derivative, wherein air leakage is judged when the first derivative is smaller than a preset value 1, the radius of an air leakage hole is large, and the detection cavity is marked as 'pollution';
if the gas leakage is larger than the preset value 1, entering a second derivative judgment stage, if the gas leakage is smaller than the preset value 2, marking the detection cavity as 'polluted' and the gas leakage hole gap radius is small; a second derivative greater than a preset value of 2 is a good seal. Regarding the preset values 1 and 2, theoretically, both the preset values should be 0, but when actually detecting data, the detection data may fluctuate due to the influence of factors such as high precision of the differential pressure sensor and large environmental noise. Therefore, the preset values 1 and 2 are often slightly less than 0 according to practical situations.
The data extracted in the present invention are data after the solenoid valve YV4 and the solenoid valve YV5 are opened for a certain preset time. The pressure acceleration rate is adopted to judge leakage under judgment, and only simple air blowing drying cleaning is needed to be carried out on the detection cavity, so that the drying cleaning time is greatly shortened. In the prior art, only a wind blowing cleaning mode can be used when gas leaks, only other complex cleaning modes such as cleaning can be used when liquid leaks, and in addition, the prior art cannot perform liquid leakage detection by using online detection; the invention can directly use the wind-blowing dry cleaning mode to clean the gas leakage, liquid leakage and gas-liquid leakage.
The electromagnetic valve YV4 and the electromagnetic valve YV5 are three-way electromagnetic valves, after detection is finished, the electromagnetic valve YV4 and the electromagnetic valve YV5 are communicated with a vacuum pipeline, pressure relief is started, pressure relief is closed after the pressure reaches a preset value, and pipeline connection of the electromagnetic valve YV4 and the electromagnetic valve YV5 is disconnected.
Detecting the numerical value of the differential pressure sensor within a preset time, and clearing the original pollution mark of the detection cavity if the numerical value of the differential pressure sensor does not reach a preset value; and when the detection value exceeds the preset value, compensating the preset value in the step A by taking the detection value as a compensation value.
In the implementation process, firstly, a test preparation stage is entered: closing solenoid valve YV4 and solenoid valve VY5, opening solenoid valve YV1, solenoid valve YV2, and solenoid valve YV3, and when the pressure sensor reaches the preset vacuum value, automatically controlling solenoid valve YV1 to close. The solenoid valve YV2 and the solenoid valve YV3 are closed at the same time after delaying a certain preset time after the solenoid valve YV1 receives a closing signal of the solenoid valve YV 1. The purpose of adopting a plurality of solenoid valves is in order to delay a certain time for the gas diffusion of first cavity body and second cavity body is stable, and pressure equals. The reason for setting the cavity body is that the air pumping of the vacuum pump is a slow process, and if the detection cavity body and the reference cavity body are directly pumped by the vacuum pump, the pressure gradient generated in the vacuum pumping stage is small, so that the quick opening of a valve in the water hammer effect cannot be realized, and the water hammer phenomenon is not obvious. During the test phase, solenoid valve YV1, solenoid valve YV2, solenoid valve YV3 remain closed, while solenoid valve YV4 and solenoid valve YV5 are opened. Before the electromagnetic valve is opened, the pressure value in the cavity body is obviously lower than the atmospheric pressure, and the pressure in the detection cavity body and the reference cavity body is atmospheric pressure. After the electromagnetic valve is opened, the gas flows into the second cavity body and the first cavity body from the reference cavity body and the detection cavity body respectively, and the pressure intensity of the reference cavity body and the pressure intensity of the detection cavity body are reduced sharply. The differential pressure sensor is used for detecting differential pressure in a single direction, the positive phase of the differential pressure sensor is communicated with the detection cavity, and the negative phase of the differential pressure sensor is connected with the reference cavity. And considering the leakage judgment process, if the sealed package has leakage, the gas in the sealed package overflows, and the pressure in the detection cavity is higher than that in the reference cavity. In the process of approaching the steady state, the pressure intensity in the detection cavity is always larger than that of the reference cavity, and the pressure intensity difference value is increased in speed and reduced gradually. At the moment, the leakage of the sealed package is judged mainly by judging that a current signal of the differential pressure sensor reaches a certain threshold value, namely the pressure difference value of the reference cavity and the detection cavity. When a small amount of liquid overflows from the sealed package, or residual liquid is left in the detection cavity in the previous time, the current threshold value of the differential pressure sensor cannot judge leakage. At the moment, whether the speed increase of the current signal is reduced or tends to be 0 in the increasing process is judged to judge leakage.
As shown in FIG. 2, when no sample leakage is detected, the current of the differential pressure sensor changes with time after the valve is opened, the current of the differential pressure sensor is in direct proportion to the pressure, and the detection range of the differential pressure sensor is 4-20 mA. From fig. 2, it can be seen that the gas diffusion has a short stabilization time, which is basically completed within 3 seconds, and the current increase speed in the diffusion process is from fast to slow and finally approaches a stable value.
It is emphasized that the necessity of using a reference cavity is present for several reasons. Firstly, a pressure sensor is required to replace a differential pressure sensor without adopting a reference cavity, the measurement accuracy of the pressure sensor is not high as that of the differential pressure sensor, and the pressure sensor with high accuracy is mostly sectional, namely, the measurement absolute range is short, and the universality test cannot be carried out. The cost of pressure sensors is generally higher than the cost of differential pressure sensors. Secondly, in the process of opening the electromagnetic valve YV4 and the electromagnetic valve YV5, a positive water hammer phenomenon is also generated, and in order to eliminate the disturbance influence of shock waves on a pressure field, a reference cavity is adopted for elimination.
Considering that the final effect of different detection samples is different, 10mL oral liquid is taken as an example, pores are preformed, and the data difference between the intact sample and the air leakage sample is observed. As shown in FIG. 3, the differential pressure sensor current shows 10mL of intact oral liquid sample (detailed in the sealed curve of FIG. 3), the sample with pore channel in the liquid part (detailed in the liquid curve of FIG. 3) and the sample with pore channel in the gas part (detailed in the leak1, leak2, leak3 curves of FIG. 3) after the solenoid valve YV4 and the solenoid valve YV5 are opened. As can be seen from the figure, the intact sample of this example achieved gas diffusion stabilization within 5 seconds and remained around 5.8mA, the void was stabilized around 7.4mA in the liquid portion of the sample, and the void was stabilized around 12mA in the gas portion of the sample. The leak1, leak2 and leak3 curves indicate that the sample to be detected is the current change condition with different gas contents (such as oral liquid, which contains gas with different contents). And the leakage of liquid and gas can be judged from the final stable value, and the leakage of gas can be judged most obviously. It can be seen in the test curves for the five samples performed that the sample pores have a significant slope decrease, regardless of whether they leak in the air or liquid portion. Thus, leaks can be judged by data processing of the system and method of the present invention.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A quick vacuum leak detection system is characterized in that: the vacuum pipeline comprises a vacuum pipeline (8) with one end connected with a vacuum pump (1), wherein the vacuum pipeline is sequentially provided with a solenoid valve YV1 for controlling the on-off of the vacuum pipeline and a pressure sensor (2) for detecting the pressure of the vacuum pipeline, the other end of the vacuum pipeline is provided with a solenoid valve YV2 and a solenoid valve YV3 in parallel, the vacuum pipeline further comprises a first cavity body (3), a second cavity body (4), a detection cavity body (5) internally provided with a sample (51) to be detected, a reference cavity body (6) internally provided with a reference entity (61) and a differential pressure sensor (7), and the vacuum pipeline where the solenoid valve YV2 is located is sequentially communicated with the first cavity body, the solenoid valve YV4 and the detection cavity body until the vacuum pipeline is communicated to the normal phase of the differential pressure sensor; and the vacuum pipeline where the electromagnetic valve YV3 is located is sequentially communicated with the second cavity, the electromagnetic valve YV5 and the reference cavity until the vacuum pipeline is communicated to the negative phase of the differential pressure sensor.
2. The rapid vacuum leak detection system of claim 1, wherein: the volume of the reference entity is larger than the volume of the sample to be detected.
3. A method of leak detection using the rapid vacuum leak detection system of any of claims 1-2, comprising the steps of:
the method comprises the following steps: opening an electromagnetic valve YV1, an electromagnetic valve YV2 and an electromagnetic valve YV3, closing an electromagnetic valve YV4 and an electromagnetic valve YV5, opening a vacuum pump, closing an electromagnetic valve YV1 when a pressure sensor reaches a set threshold value, and closing the vacuum pump in a delayed manner;
step two: after the pressure values of the first cavity and the second cavity are equal and stable for a certain time, closing the electromagnetic valve YV2 and the electromagnetic valve YV 3; if the pressure sensor can not be maintained stable, the system is closed to wait for the instrument to be checked, the first step is executed after the instrument is checked, and if the pressure sensor is maintained stable, the next step is executed;
step three: and simultaneously opening the electromagnetic valve YV4 and the electromagnetic valve YV5, starting to record data of the differential pressure sensor, wherein the data of the differential pressure sensor is a current value, and then performing leak detection judgment according to the current value.
4. The rapid vacuum leak detection system and method of claim 3, wherein: the current value leak detection judging method comprises the following steps:
step A: judging that the signal current value of the differential pressure sensor reaches a preset value within preset time, and judging that the signal current value of the differential pressure sensor leaks;
and B: if the signal current value of the differential pressure sensor does not reach the preset value within the preset time, entering the next step to execute the next judgment mode;
and step C, entering a pressure acceleration judging mode, and utilizing discrete data to carry out interpolation judgment to judge whether leakage exists.
5. The rapid vacuum leak detection method of claim 4, wherein: the specific method for performing interpolation judgment by adopting the discrete data comprises the following steps:
step a: deriving current value data of the differential pressure sensor according to sampling frequency to form equidistant discrete data;
step b: the first derivative and the second derivative are obtained by adopting a difference method on the equidistant discrete data,
step c: judging the first-order derivative, wherein air leakage is judged when the first-order derivative is smaller than a preset value 1, and the radius of an air leakage hole is large; if the air leakage is larger than the preset value 1, entering a second derivative judgment stage, if the air leakage is smaller than the preset value 2, judging that air leakage exists, and enabling the radius of the air leakage hole to be small; a second derivative greater than a preset value of 2 is a good seal.
6. The rapid vacuum leak detection method of claim 5, wherein: the extracted data are data after the solenoid valve YV4 and the solenoid valve YV5 are opened for a certain preset time.
7. The rapid vacuum leak detection method of claim 5, wherein: the electromagnetic valve YV4 and the electromagnetic valve YV5 are three-way electromagnetic valves, after detection is finished, the electromagnetic valve YV4 and the electromagnetic valve YV5 are communicated with a vacuum pipeline, pressure relief is started, pressure relief is closed after the pressure reaches a preset value, and pipeline connection of the electromagnetic valve YV4 and the electromagnetic valve YV5 is disconnected.
8. The rapid vacuum leak detection method of claim 7, wherein: and (3) detecting the value of the differential pressure sensor within a preset time, and compensating the preset value in the step (A) by taking the detected value as a compensation value after the value exceeds the preset value.
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| CN202110842077.3A CN113567071A (en) | 2021-07-26 | 2021-07-26 | Rapid vacuum leak detection system and method |
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| CN115200802A (en) * | 2022-07-27 | 2022-10-18 | 济南赛成电子科技有限公司 | Intelligent controllable vacuum device and system |
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