Detection method of gas sensor probe

Abstract

The invention discloses a detection method of a gas sensor probe. The detection method comprises the following steps: step a, detecting the gas tightness of the probe through a helium detection method; and b, carrying out air tightness detection on the probe which is detected to be qualified in the step a through a liquid detection method, and if the detection result is qualified, determining that the air tightness of the probe is qualified. The detection method of the gas sensor probe can be used for detecting the gas tightness of the probe and the reliability of structural connection, so that the working reliability of the probe which is detected to be qualified is better, and the service life is longer.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sensor probe detection, and in particular to a detection method for a thermal conductivity type gas sensor probe. BACKGROUND

[0002] With the increasing popularity of environmental protection concepts, green and environmentally friendly air conditioners using new refrigerants and variable frequency series will be the industry development trend. Refrigerant, also known as refrigeration working medium, is the working substance in the refrigeration system. At present, there are more than 80 substances that can be used as refrigerants, and the most common refrigerants include freon (including R22, R134a, R407c, R410a, R32, etc.), ammonia (NH3), water (H2O), carbon dioxide (CO2), and a few hydrocarbons (such as R290, R600a).

[0003] Refrigerant is a medium used in refrigeration systems and is widely used in the fields of household air conditioners, commercial air conditioners, and automobile air conditioners. However, traditional refrigerants such as freon have a non-negligible impact on atmospheric ozone layer destruction and global warming. In order to address environmental issues, the application of new generation environmentally friendly refrigerants is urgent. New generation environmentally friendly refrigerants have lower temperature width, higher energy efficiency and refrigeration effect. High energy efficiency refrigerants can improve the energy efficiency of the refrigeration system and reduce energy consumption. With the increasing global environmental awareness and the continuous strengthening of environmental policies, countries are increasingly restricting the use of traditional refrigerants. Many countries have introduced relevant policies to gradually phase out the use of high temperature width refrigerants, providing a broader market opportunity for new generation environmentally friendly refrigerants.

[0004] New generation refrigerants are natural carbon-hydrogen refrigerants that can be obtained directly from liquefied gas. They do not contain chlorine atoms in the molecule, so the ODP value is zero, and they have no destructive effect on the ozone layer. At the same time, the GWP value is close to 0, and they have no impact on the greenhouse effect. They can be widely used in the fields of household air conditioners, commercial refrigeration equipment, and automobile air conditioners. However, new generation refrigerants are flammable and explosive. In order to improve safety, safety detection is required, and various detection sensors for detecting refrigerants have emerged. In order to improve the detection accuracy of refrigerant detection sensors, it is necessary to ensure the working reliability of the probe of the detection sensor. For example, if the gas tightness of the probe is unqualified, it will cause the detection failure of the probe and affect the detection accuracy.

[0005] In view of the above, how to provide a detection method for detecting the reliability of the probe has become a technical problem to be solved by those skilled in the art. SUMMARY

[0006] Therefore, the present application provides a detection method for a gas sensor probe, which can be used to detect the reliability of the probe.

[0007] To achieve the above object, the present application provides the following technical solutions.

[0008] A detection method of a gas sensor probe, comprising the following steps:

[0009] Step a, detecting the gas tightness of the probe by helium detection method;

[0010] Step b, detecting the gas tightness of the probe which is qualified in step a by liquid detection method, and if the detection result is qualified, the gas tightness of the probe is qualified.

[0011] From the above technical solutions, the detection method of the gas sensor probe provided by the above technical solutions comprises helium detection method and liquid detection method, and the helium detection method is applied to the detection of the probe with small volume for the first time. The helium detection of the probe can realize the detection of the small leak of the probe, and the liquid detection of the probe can realize the detection of the larger leak of the probe. By combining the two detection methods, the detection of the small leak and the detection of the larger leak can be realized, the detection reliability of the probe in the whole domain is met, and the detection reliability of the probe is improved. BRIEF DESCRIPTION OF DRAWINGS

[0012] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0013] Figure 1 A schematic diagram of the detection method of the gas sensor probe provided by an embodiment of the present application;

[0014] Figure 2 A structural schematic diagram of the probe for detection according to an embodiment of the present application;

[0015] Figure 3 A structural schematic diagram of the cap of the probe;

[0016] Figure 4 A structural schematic diagram of the tube base of the probe;

[0017] Figure 5 A schematic diagram of the pulling force applied to the cap and the tube base during the pulling force detection according to an embodiment of the present application.

[0018] Wherein:

[0019] 1, cap, 2, tube base. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative work, fall within the protection scope of the present application.

[0021] The detection method of the probe of the present application can be used to detect the air tightness and structural connection reliability of the probe, so that the working reliability of the qualified probe is better and the service life is longer. The probe of the present application is generally a gas sensor, in particular a thermal conductivity type gas sensor, and especially a thermal conductivity type gas sensor suitable for refrigerant detection.

[0022] With reference to Figure 1 The detection method of the gas sensor probe of the present application comprises the following steps:

[0023] Step a: detecting the air tightness of the probe by helium detection method;

[0024] Step b: detecting the air tightness of the probe qualified in step a by liquid detection method, and if the detection result is qualified, the air tightness of the probe is qualified.

[0025] With reference to Figures 2 to 4 The probe comprises a pipe cap 1 and a pipe base 2 welded together, and the inner cavity of the pipe cap 1 needs to be sealed. If there is air leakage, it will directly lead to the failure of the probe detection, so the air tightness detection of the probe is very important. The detection method of the probe of the present application can effectively detect the air tightness of the probe by using helium detection and liquid detection in combination. At the same time, the detection method must first perform helium detection to exclude small range leaks, and then perform liquid detection to exclude large range leaks. If liquid detection method is used first, residual liquid molecules will affect the helium detection instrument and affect the detection result. However, if helium detection is performed first, the influence of liquid on the detection result can be avoided.

[0026] The present invention innovatively applies the helium detection method to the airtightness detection of thermal conductivity gas sensors. Before the present invention, helium detection was generally used for the airtightness detection of larger containers. The helium detection process includes two steps: helium pressurization and helium element detection. Before detecting the helium element, it is necessary to evacuate the inside of the helium detection equipment to remove the air inside the helium detection equipment, so as to avoid the helium in the air inside the helium detection equipment from affecting the detection result of leak detection. For the airtightness detection of larger containers, due to the relatively large cavity space of the container, even if there are relatively large holes in the container to be detected, when evacuating, some helium flows out through the holes along with the evacuation. However, due to the relatively large volume of the container to be detected and the relatively short evacuation time, not all the helium leaked into the container can be evacuated, so it will not affect the detection result. Therefore, for detecting the airtightness of larger containers, the accuracy of helium detection is very high and there will be no missed detection.

[0027] If the helium detection is directly applied to the airtightness detection of small-volume items such as detection probes, if the hole in the probe is relatively large, when evacuating the helium detection equipment for detecting the helium element, since there is a stabilization time for the helium detection equipment to evacuate, if the leak in the probe is relatively large, the helium leaked into the probe will be evacuated along the leak during evacuation, so the helium in the probe cannot be detected by the helium detection equipment, and the probe with a relatively large leak will be misjudged as a qualified product, and the accurate judgment of airtightness cannot be achieved.

[0028] Through the creative work of the inventor, for the airtightness detection of the probe, it is found that the effective range of helium detection is 1.2×10 3 , 3 , -8 , 3 , -7 , -12 , -7 ,

[0029] , ~7.5×10 -7 Pa.m 3 / s. For the detection in the range of >7.5×10 -7 Pa.m 3 / s, the result of helium detection is inaccurate. The reason is that for a probe with a relatively large leak, since the helium detection instrument requires a certain time to evacuate, the helium will be evacuated during evacuation. After the air in the helium detection instrument is evacuated and then detected, it will be misjudged as a qualified product. That is, helium detection for detecting the airtightness in a specific range cannot be used to detect products with较多漏气. And the effective detection range of the liquid detection method is greater than 1.0×10 -8 Pa.m 3 / s, which can be used to detect products with较多漏气. By using the two methods in combination, the detection requirements of the gas sensor probe are met.

[0029] The detection method of the gas sensor probe of the present application includes helium detection method and liquid detection method, and can realize the detection of the small leakage of the probe. The liquid detection method can realize the detection of the probe with larger leakage. The combination of the two detection methods realizes better airtightness detection of the probe and improves the reliability of the probe detection. The detection method of the probe of the present application applies the helium detection method to the small-volume product, which not only creatively applies the helium detection method to the small-volume product, but also solves the problem that the helium detection method is difficult to be applied to the airtightness detection of the small-volume product, and meets the demand of the detection reliability of the probe.

[0030] In addition, the welding position of the cap 1 and the base 2 may have welding defects such as cavities or cracks due to burrs or dust. In order to facilitate the detection of the connection strength of the welding position of the cap 1 and the base 2 of the probe, the present application adds a tensile force detection step for detecting the tensile strength of the welding position of the cap 1 and the base 2. The tensile force detection is used to detect the connection strength of the welding position of the cap 1 and the base 2, so as to avoid the influence of the too thin welding layer of the welding position of the probe on the working reliability of the probe. When the tensile force detection is performed, the probes need to be batched for sampling inspection, and the tensile force of the sampled probes is detected. If the tensile force of the sampled probes is qualified, it is determined that the structure welding of the corresponding batch of probes is qualified. Since the tensile force detection is destructive, for each batch of probes, the tensile force detection can be performed on a certain number of probes. Since the welding process and parameters of the cap 1 and the base 2 of the same batch are basically the same, the tensile strength of the welding position of the probes of the same batch is similar. Therefore, sampling inspection can be performed.

[0031] The tensile force detection can be performed on the probes that pass the steps a and b, or can be directly performed on the probes that do not undergo airtightness detection. The batch of probes with tensile force greater than the set value is the qualified welding product. The unqualified welding batch of probes is removed. The detection of the probe not only includes the airtightness detection of the probe, but also includes the tensile force detection of the welding strength. The sequence of the two detections is not limited.

[0032] In a specific embodiment, the detection method of the gas sensor probe of the present application includes helium detection method, liquid detection method and tensile force detection. The helium detection method and the liquid detection method are combined together for airtightness detection of the probe, and the airtightness detection result is more reliable. The tensile force detection of the probe facilitates the detection of the reliability of the welding connection of the probe, and the unqualified welding batch of probes is removed. The detection method of the gas sensor probe of the present application not only guarantees the airtightness of the probe, but also guarantees the reliability of the structure connection of the probe, so that the working reliability of the qualified probe is better and the service life is longer.

[0033] Further, the helium detection method comprises the following steps:

[0034] Step a1, placing the to-be-tested probe on the detection tray.

[0035] The detection tray is provided with a plurality of array-arranged placement grooves, each of which is used to place a probe. The pipe cap 1 is inserted into the placement groove, so that the welding position of the pipe cap 1 and the pipe base 2 is outside the placement groove, avoiding the influence of the structure of the placement groove on the air tightness detection result of the welding position seam.

[0036] Step a2, placing the detection tray with the probe in a helium tank, sealing the tank, and then filling the tank with helium to a set pressure value, maintaining the pressure for a set period of time, and then releasing the pressure to the normal pressure state. After the helium pressure is completed, the pressure relief valve is opened for 10 seconds, and when the value displayed on the pressure gauge is 0, the helium tank is opened to take out the probe.

[0037] In an embodiment, the set pressure value is 515-525 Kpa, and the set time period is 2.5-4 hours. In other embodiments, the set pressure value and the set time period can be modified by those skilled in the art according to actual needs. The helium tank is a sealed tank for helium pressure, which is used to realize helium pressure on the probe placed inside, so that when the probe has a leak, high-pressure helium will enter the inside of the probe through the leak, thereby facilitating the next step of detection.

[0038] Step a3, taking out the to-be-tested probe and placing it in a helium mass spectrometric leak detector to detect whether the probe leaks. The probes that have completed the helium pressure are tested one by one for the leak rate using the helium mass spectrometric leak detector.

[0039] In this step, the helium detection device uses a helium mass spectrometric leak detector. In order to avoid the influence of helium on the surface of the probe on the detection result, the surface of the to-be-tested probe is blown with high-pressure air before being placed in the helium mass spectrometric leak detector, so as to improve the accuracy of helium detection. Before detection in the helium mass spectrometric leak detector, the helium mass spectrometric leak detector is first evacuated for a stable time of 8.5-9.5 seconds to remove the air in the helium mass spectrometric leak detector, avoiding the influence of air on the detection of helium.

[0040] In this step, if the probe has a large leak, the helium in the probe will be extracted during the evacuation, so that the helium in the probe with a large leak will not be detected by the helium mass spectrometric leak detector, and the probe will be mistakenly considered as a qualified product.

[0041] In order to compensate for the defects of the helium detection method in the detection of the air tightness of the probe, the air tightness of the probe of the present application also needs to be further detected by a liquid detection method, so as to detect the probes with large leaks that cannot be detected by the helium detection method. Specifically, the liquid detection method comprises the following steps:

[0042] Step b1, placing the probe in the detection container containing liquid, the probe is immersed in the liquid.

[0043] The detection container is a good sealing container, the height of the detection container is greater than the height of the probe, so as to ensure the detection of each probe. Each of the detection container can be placed in a plurality of probes, so as to carry out airtightness detection on a plurality of probes at the same time. In order to facilitate the taking and placing of the probe, the detection container comprises a container body and a container cover which are sealingly connected together, and the container body is used for containing liquid. In order to facilitate the observation of whether there is gas leakage in the probe, the detection container can be a transparent container, which is convenient for observing the bubbles generated in the liquid in the container. In order to improve the effect of observing the bubbles, the detection container is provided with a lighting lamp outside the detection container, and the lighting lamp is arranged at one side of the detection container.

[0044] Step b2, covering the container cover, and vacuumizing the detection container through the vacuumizing system, so that the vacuum degree in the detection container is less than 20Kpa.

[0045] The air outlet of the vacuumizing system is sealingly connected with the air hole on the container cover, so as to facilitate the vacuumizing of the detection container by the vacuum pump of the vacuumizing system.

[0046] Step b3, observing whether there is bubble out of the probe. Continuously observe for 1min, and see whether there is bubble out of the probe. If there is no bubble out of the probe, the airtightness of the probe is qualified, and if there is bubble out of the probe, the airtightness of the corresponding probe is unqualified. As other embodiments, the detection can also use visual recognition detection.

[0047] Specifically, each probe needs to be detected for airtightness, and helium detection and liquid detection are needed, so as to realize reliable detection of the airtightness of the probe and ensure that each probe can be normally used.

[0048] In order to avoid the pollution of the liquid to the probe or the influence on the surface quality of the probe, the liquid in the detection container is preferably alcohol. Using alcohol as the detection liquid has less influence on the surface quality of the probe, and after taking out the probe, the alcohol will volatilize quickly, so that the probe does not need to be wiped or other cleaning treatment, which improves the detection efficiency.

[0049] In a specific embodiment, the pulling force detection comprises the following steps:

[0050] Step c1, a first through hole is arranged on the pipe base 2 of the probe, and a second through hole is arranged on the pipe cap 1. In this step, the first through hole and the second through hole are arranged to facilitate the fixation of one of the two components of the probe and the application of force to the other, that is, to facilitate the detection of the pulling force. In order to improve the stability of the detection process, the first through hole and the second through hole are coaxially arranged. The second through hole is coaxially arranged with the pipe cap 1, and the pipe base 2 is coaxially arranged with the first through hole, so as to improve the reliability of the pulling force detection and reduce the interference factors caused by different centers.

[0051] Step c2, the pipe cap 1 is fixed at the end through the second through hole, and the pipe base 2 is pulled through the force measuring device connected at the position of the first through hole, as shown in the figure. The direction of the applied force is indicated by the arrow. It is detected whether the pulling force value when the pipe base 2 is pulled away from the pipe cap 1 reaches the set pulling force value. If it is greater than or equal to the set pulling force value, the probe is qualified. Figure 5

[0052] In an embodiment, the set pulling force value is 900N. During detection, the pipe cap 1 is fixed by the fixing hook extending into the second through hole, and the pipe base 2 is axially pulled by the force measuring device connected in the first through hole, and the size of the pulling force is detected, so as to judge whether the welding strength of the probe meets the standard.

[0053] The detection method of the gas sensor probe of the present application adopts two detection methods of liquid detection and helium detection to detect the air tightness of the probe, realizes wider range detection, and the liquid detection makes up for the detection blind area of the helium detection. The pulling force detection for the pipe cap 1 and the pipe base 2 is increased, so as to facilitate the detection of the connection strength of the welding position of the pipe cap 1 and the pipe base 2, and avoid the problem of short-term failure of the probe caused by too thin welding seam at the welding position. The detection method of the gas sensor probe of the present application improves the reliability of the probe detection, not only guarantees the air tightness, but also guarantees the connection reliability of the welding part. The quality of the qualified probe is better, and the service life is longer.

[0054] In the description of the present application, it should be understood that the terms "upper", "lower", "vertical", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0055] In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include one or more of the features. ​

[0056] The various embodiments described in this specification are presented by way of example, and each embodiment is not necessarily composed of all features described with respect to other embodiments. Each embodiment describes a distinct aspect of the present application, and each aspect can be used in combination with one or more other aspects.

[0057] The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A detection method for a gas sensor probe, characterized in that, Includes the following steps: Step a: Detect the airtightness of the probe using a helium detection method; Step b: Perform an airtightness test on the probe that passed the test in step a using the liquid testing method. If the test result is qualified, then the probe is qualified for airtightness.

2. The detection method of the gas sensor probe according to claim 1, characterized in that, The probes are sampled in batches for inspection. The sampled probes are subjected to pull-out force testing. If the pull-out force of the sampled probes is qualified, the welding of the corresponding batch of probes is qualified.

3. The detection method of the gas sensor probe according to claim 1 or 2, characterized in that, The helium detection method includes the following steps: Place the probe to be tested on the testing tray; Place the detection tray containing the probe into a helium cylinder, seal it, fill the helium cylinder with helium and pressurize it to the set pressure value, maintain the pressure for a set time period, and then release the pressure to normal pressure. Remove the probe to be tested and place it in a helium mass spectrometer leak detector to check for leaks.

4. The detection method of the gas sensor probe according to claim 3, characterized in that, The set pressure value is 515-525 kPa, and the set time period is 2.5-4 hours.

5. The detection method of the gas sensor probe according to claim 3, characterized in that, Before the probe to be tested is placed into the helium mass spectrometer leak detector, the surface of the probe is purged with high-pressure air.

6. The detection method of the gas sensor probe according to claim 1 or 2, characterized in that, The liquid detection method includes the following steps: The probe is placed in a detection container filled with liquid, and the probe is immersed in the liquid; Cover the container with the lid and use a vacuum system to evacuate the test container to make the vacuum level inside the test container less than 20 kPa; Observe whether there are bubbles emerging from the test container. If no bubbles emerge, it indicates that the probe's airtightness is qualified.

7. The detection method of the gas sensor probe according to claim 6, characterized in that, The testing container is a transparent container, and a light is provided on one side of the testing container.

8. The detection method of the gas sensor probe according to claim 6 or 7, characterized in that, The liquid in the testing container is alcohol.

9. The detection method of the gas sensor probe according to any one of claims 1-8, characterized in that, The pull-out force detection includes the following steps: A first through hole is provided in the probe's tube seat, and a second through hole is provided in the tube cap; The tube cap is fixed in place through the second through hole. The tube seat is pulled by a force measuring device inserted through the first through hole. The pulling force when the tube seat and the tube cap are pulled apart is detected to see if the pulling force reaches the set pulling force value. If it is greater than or equal to the set pulling force value, the probe is qualified.

10. The detection method of the gas sensor probe according to claim 9, characterized in that, The set tensile force value is 900N.

Images