CN115248098A

CN115248098A - Leak test standard and leak test system

Info

Publication number: CN115248098A
Application number: CN202211019218.2A
Authority: CN
Inventors: 姜德志; 张儒锋; 洪浩瀚; 许镜河; 林立鹏; 谢中司; 李波; 单金当
Original assignee: Shangteng Technology Guangzhou Co ltd
Current assignee: Shangteng Technology Guangzhou Co ltd
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2022-10-28

Abstract

The invention relates to a leak test standard and a leak test system, the leak test standard includes: the standard device comprises a standard device cavity, a test device and a test device, wherein the standard device cavity is provided with an accommodating cavity, an evaporation cavity and a volatilization hole, the accommodating cavity is communicated with the evaporation cavity, the evaporation cavity is communicated with the outside through the volatilization hole, the accommodating cavity is used for accommodating electrolyte, and the volatilization hole is used for being communicated with a leakage test device; annotate the piece, annotate the piece set up in on the etalon cavity, just but annotate the piece open closed intercommunication in hold the chamber, annotate the piece be used for to hold the chamber and annotate electrolyte. According to the leakage test standard device, the leakage condition of the electrolyte with stable and continuous speed can be conveniently obtained by selecting the proper standard device cavity model, so that a standard value is provided for a leakage test to be referred to, and the accuracy and reliability of the electrolyte leakage test of the tested workpiece such as a lithium ion battery are improved.

Description

Leak test standard and leak test system

Technical Field

The invention relates to the technical field of lithium ion battery reliability testing, in particular to a leakage testing standard device and a leakage testing system.

Background

Batteries, battery modules, power battery packs and the like are visible everywhere in life, are widely applied to equipment such as automobiles, mobile phones, earphones and the like, the safety of the batteries is more important along with the wide application of the batteries, and when the sealing performance of the batteries is defective, on one hand, substances such as external air, water vapor and the like easily invade the interior of the batteries to cause safety problems; on the other hand, gas generated inside the battery or electrolyte in the gas is easy to leak outwards, which causes safety problems. Therefore, the battery needs to be tested for sealing before shipment.

Disclosure of Invention

Accordingly, there is a need for a leak test standard and a leak test system that can effectively provide a uniform leak value and verify the reliability of the test system.

The technical scheme is as follows: a leak test standard, the leak test standard comprising: the standard device comprises a standard device cavity, a test device and a test device, wherein the standard device cavity is provided with an accommodating cavity, an evaporation cavity and a volatilization hole, the accommodating cavity is communicated with the evaporation cavity, the evaporation cavity is communicated with the outside through the volatilization hole, the accommodating cavity is used for accommodating electrolyte, and the volatilization hole is used for being communicated with a leakage test device; annotate the piece, annotate the piece set up in on the etalon cavity, just but annotate the piece open closed intercommunication in hold the chamber, annotate the piece be used for to hold the chamber and annotate electrolyte.

Above-mentioned leak test etalon, when carrying out electrolyte leakage test to the tested work piece such as lithium ion battery, at first according to the electrolyte content of the product of being tested and the size of leaking the hole, select the etalon cavity that has corresponding size hole of volatilizing, through annotating the piece to holding intracavity filling electrolyte, after the filling completion, will volatilize the hole and communicate with the leak test equipment, because the electrolyte that holds the intracavity can evaporate or volatilize, enter into the leak test through the hole of volatilizing and detect, the cross-sectional area that holds the chamber can simulate the area of volatilizing of the work piece electrolyte of being tested, the hole of volatilizing can simulate the size of leaking the hole on the work piece of being tested, consequently, through selecting suitable etalon cavity model, can conveniently obtain the stable continuous electrolyte's of speed leakage condition, thereby provide the standard value for the leak test and refer to, be favorable to improving accuracy and the reliability of being tested work piece electrolyte leakage test such as lithium ion battery.

In one embodiment, the leak test standard further comprises a gas-permeable membrane disposed between the accommodating chamber and the evaporation chamber, the gas-permeable membrane being configured to allow gas to pass therethrough and to isolate liquid.

In one embodiment, the cavity of the standard device is further provided with an opening and a volatilization piece, the evaporation cavity is communicated with the outside through the opening, the volatilization piece is detachably connected to the wall of the opening, the volatilization hole is formed in the volatilization piece, and the evaporation cavity is communicated with the opening through the volatilization hole.

In one embodiment, the leak test standard further comprises an evacuation member openably and closably communicated with the evaporation cavity, and the evacuation member is used for connecting a vacuum-pumping device to vacuum the evaporation cavity.

In one embodiment, the leak test standard device further comprises a liquid level indicator, a piston and a reset piece, wherein the piston is movably connected to the inner wall of the accommodating cavity, the liquid level indicator is connected with one side, back to the evaporation cavity, of the piston, the reset piece is connected between the piston and the wall of the accommodating cavity, and the reset piece is matched with the piston in a reset mode.

In one embodiment, the cavity of the standard device is further provided with an indicating cavity, the indicating cavity is provided with a marking piece, and the liquid level indicating piece extends into the indicating cavity and is in sliding fit with the indicating cavity.

In one embodiment, the circumferential side wall of the piston is provided with a first seal which is in sealing engagement with the circumferential inner wall of the receiving chamber.

In one embodiment, the etalon cavity comprises a first cavity and a second cavity, the first cavity is detachably connected with the second cavity, the accommodating cavity is arranged in the first cavity, and the evaporation cavity and the volatilization hole are arranged in the second cavity.

In one embodiment, the etalon housing further comprises a second seal disposed between the first housing and the second housing, the first housing being in sealing engagement with the second housing via the second seal.

A leak testing system comprising leak testing apparatus and a leak testing standard as claimed in any preceding claim.

Above-mentioned leak testing system, when carrying out electrolyte leakage test to the tested work piece such as lithium ion battery, at first according to the electrolyte content of the product of being tested and the size of leaking the hole, select the etalon cavity that has corresponding size hole of volatilizing, through annotating the piece and filling electrolyte to holding the intracavity, after the filling completion, will volatilize the hole and communicate with leak testing equipment, because the electrolyte that holds the intracavity can evaporate or volatilize, enter into the leak test through the hole of volatilizing and detect, the cross-sectional area that holds the chamber can simulate the area of volatilizing of the work piece electrolyte of being tested, the hole of volatilizing can simulate the size of leaking the hole on the work piece of being tested, consequently, through selecting suitable etalon cavity model, can conveniently obtain the stable continuous electrolyte's of speed leakage condition, thereby provide the standard value for the leak test and refer to, be favorable to improving accuracy and the reliability of being tested work piece electrolyte leakage test such as lithium ion battery.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention.

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a first diagram illustrating an overall configuration of a leak testing standard according to an embodiment;

fig. 2 is a schematic diagram of an overall structure of the leak test standard in an embodiment.

Description of reference numerals:

100. a leak test standard; 110. a etalon cavity; 111. an accommodating chamber; 112. an evaporation chamber; 113. a volatilization hole; 114. a volatile tablet; 115. an indicator chamber; 116. a first cavity; 117. a second cavity; 118. a second seal member; 120. filling a piece; 130. a gas permeable membrane; 140. an evacuation member; 150. a liquid level indicator; 151. a piston; 152. a reset member; 153. a first seal.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, fig. 1 is a schematic diagram illustrating an overall structure of a leak test standard 100 according to an embodiment of the present invention, in which the leak test standard 100 according to the embodiment of the present invention includes: an etalon housing 110 and a filler piece 120. The standard device cavity 110 is provided with a containing cavity 111, an evaporation cavity 112 and an evaporation hole 113, the containing cavity 111 is communicated with the evaporation cavity 112, the evaporation cavity 112 is communicated with the outside through the evaporation hole 113, the containing cavity 111 is used for containing electrolyte, and the evaporation hole 113 is used for being communicated with leakage testing equipment. Annotate piece 120 and set up on etalon cavity 110, and annotate piece 120 openable intercommunication in holding chamber 111, annotate piece 120 and be used for to holding chamber 111 notes electrolyte.

The leakage test standard device 100 selects the standard device cavity 110 with the volatilization holes 113 with corresponding sizes according to the electrolyte content of a tested product and the sizes of the leakage holes when electrolyte leakage test is carried out on the tested workpiece such as a lithium ion battery, the electrolyte is filled into the containing cavity 111 through the filling piece 120, after the filling is completed, the volatilization holes 113 are communicated with the leakage test equipment, the electrolyte in the containing cavity 111 can be evaporated or volatilized and enters the leakage test through the volatilization holes 113 to be detected, the volatilization area of the electrolyte of the tested workpiece can be simulated by the cross section area of the containing cavity 111, the sizes of the leakage holes in the tested workpiece can be simulated by the volatilization holes 113, therefore, the leakage condition of the electrolyte with stable and continuous speed can be conveniently obtained by selecting the proper model of the standard device cavity 110, reference is provided for the leakage test, and the accuracy and the reliability of the electrolyte leakage test of the tested workpiece such as the lithium ion battery can be improved.

Specifically, the filling member 120 can be in open-close communication with the accommodating cavity 111, and it is understood that the filling member 120 can be in two states of open and close, when electrolyte needs to be filled into the accommodating cavity 111, the filling member 120 is opened, so that the accommodating cavity 111 is communicated with the outside through the filling member 120, and therefore filling can be performed on the accommodating cavity 111 through the filling member 120. After filling, the filling piece 120 can be closed, so that the accommodating cavity 111 is closed, and the test effect is ensured.

It should be noted that the leakage test standard device 100 can be used for testing electrolyte in a lithium ion battery, and is also applicable to leakage test of liquid volatilization in other tested workpieces, for example, leakage conditions such as a chemical battery and an electrolytic capacitor need to be filled with electrolyte, and leakage of electrolyte seriously affects energy storage capacity, service life and even use safety of the chemical battery and the electrolytic capacitor.

The leakage of electrolyte from the leak/leak in the battery body is mainly affected by the following factors: the size of the leakage hole, the pressure difference between the inner side and the outer side of the leakage hole, the ambient temperature and the exposed volatilization area of the electrolyte after leakage. Because the cross-sectional area of the accommodating cavity 111 in the standard device cavity 110 can simulate the exposed volatilization area of the electrolyte of the workpiece to be tested, and the size of the volatilization hole 113 can correspond to the size of the electrolyte leakage hole of the workpiece to be tested, different types of standard device cavities 110 can be selected for the leakage test of different workpieces to be tested, wherein the different types of standard device cavities 110 are provided with the accommodating cavities 111 with different cross-sectional areas and the volatilization holes 113 with different diameters so as to correspondingly simulate the leakage states of different workpieces to be tested, or the cross-sectional area and the volatilization holes 113 of the accommodating cavities 111 are adjusted, manufactured and processed in the same standard device cavity 110, thereby being suitable for different workpieces to be tested.

In one embodiment, referring to FIG. 1, the leak test standard 100 further includes a gas permeable membrane 130. The gas-permeable membrane 130 is disposed between the accommodating chamber 111 and the evaporation chamber 112, and the gas-permeable membrane 130 is used for allowing gas to pass through and isolating liquid. So, the molecule of gaseous state, gaseous phase can see through ventilative diaphragm 130, and liquid, the molecule of liquid phase can not see through ventilative diaphragm 130, consequently, holds the electrolyte in chamber 111 and can not enter into evaporation chamber 112, is favorable to making during volatile gas enters into evaporation chamber 112 to from volatilizing hole 113 leakage, avoid electrolyte to leak, also be favorable to avoiding liquid molecule to volatilize and block up volatilizing hole 113, guarantee the leakage efficiency of electrolyte.

When the size of the volatilization hole 113 is the same as the diameter of the evaporation cavity 112, that is, the opening of the evaporation cavity 112 is directly exposed and is communicated with the leakage detection device, the cross-sectional area of the evaporation cavity 112 can simulate the exposed volatilization area of the electrolyte of the tested workpiece, and the standard leakage rate of the leakage test standard 100 can be determined according to the area.

In one embodiment, referring to FIG. 1, the etalon housing 110 is further provided with openings and a volatilization plate 114. The evaporation cavity 112 is communicated with the outside through an opening, the volatilization piece 114 is detachably connected to the wall of the opening, the volatilization hole 113 is formed in the volatilization piece 114, and the evaporation cavity 112 is communicated with the opening through the volatilization hole 113. Thus, the size of the volatilization hole 113 can be conveniently adjusted by replacing different volatilization sheets 114, so that the same standard device cavity 110 can be suitable for different tested workpieces, the equipment cost of the leakage test can be reduced, and the working efficiency of the leakage test can be improved.

In one embodiment, referring to fig. 1, the leak testing standard 100 further includes an evacuation element 140, the evacuation element 140 is in open-close communication with the evaporation cavity 112, and the evacuation element 140 is used for connecting a vacuum-pumping device to evacuate the evaporation cavity 112. In this way, by opening the evacuation member 140, the evaporation cavity 112 is communicated with the outside through the evacuation member 140, and after the evacuation device is connected, the evaporation cavity 112 can be evacuated, and the pressure of the evaporation cavity 112 can be adjusted. Since the evaporation chamber 112 communicates with the accommodation chamber 111, air inside the evaporation chamber 112 is also drawn out, thereby adjusting the leakage efficiency of the electrolyte leakage gas by adjusting the pressure.

Referring to fig. 2, fig. 2 is a schematic diagram illustrating an overall structure of the leak test standard 100 according to an embodiment of the present invention, and in one embodiment, the leak test standard 100 further includes a liquid level indicator 150, a piston 151, and a reset member 152. Piston 151 is movably connected to the inner wall of accommodating cavity 111, liquid level indicator 150 is connected with one side of piston 151 opposite to evaporation cavity 112, reset piece 152 is connected between piston 151 and the cavity wall of accommodating cavity 111, and reset piece 152 is in reset fit with piston 151. For example, the return member 152 is a spring. In this way, when the evaporation cavity 112 is evacuated through the evacuation port, air in the accommodating cavity 111 is also evacuated, so that the piston 151 moves toward the air-permeable diaphragm 130, the spring connected to the piston 151 is stretched, when the piston 151 moves to the electrolyte filling port, the vacuum port is closed, and at this time, the liquid level indicator 150 is at the lowest liquid level. The pole that links to each other with piston 151 is to the blank pipe, and the outermost end of pole is equipped with the indicator, and level indicator 150 can monitor the liquid level of the electrolyte that holds in the chamber 111, and the spring is owing to stretched, owing to reset the cooperation, in order to resume original state, exerts the effort of keeping away from evaporation chamber 112 to piston 151, holds chamber 111 owing to by the evacuation, and pressure is less than atmospheric pressure, and consequently atmospheric pressure can exert the effort towards evaporation chamber 112 to piston 151, and the force balance reaches the equilibrium. When electrolyte is added into the accommodating cavity 111 through the filling piece 120, the pressure of the accommodating cavity 111 is changed, so that the atmospheric pressure difference between the accommodating cavity 111 and the rod of the piston 151 is reduced, the force applied to the piston 151 towards the evaporation cavity 112 is reduced, and at the moment, the force applied to the piston 151 by the spring away from the evaporation cavity 112 is greater than the force applied to the piston 151 towards the evaporation cavity 112, so that the spring can pull the piston 151 to move towards the direction away from the evaporation cavity 112 until the left force and the right force applied to the piston 151 reach the balance again. When holding chamber 111 and filling up electrolyte, the pressure that holds chamber 111 this moment no longer increases, and the atress of piston 151 reaches the balance again, and level indicator 150 is in the highest liquid level this moment, and evaporation chamber 112's pressure is less than the pressure that holds chamber 111 far away, and under the effect of pressure differential, the electrolyte that holds chamber 111 has the trend toward evaporation chamber 112 flow. But because ventilative diaphragm 130's isolation, electrolyte can't be through ventilative diaphragm 130, but electrolyte can be attached to on the diaphragm, make ventilative diaphragm 130 moistened, liquid electrolyte makes the electrolyte on the diaphragm gasification with higher speed under the extrusion of pressure differential, evaporation chamber 112 can be filled with to electrolyte after the gasification, gaseous electrolyte in evaporation chamber 112 flows through volatilizing hole 113, the speed of overflowing of electrolyte can be controlled through the size of control hole 113 that volatilizees, liquid level indicator 150 also can conveniently show the intracavity liquid level condition of holding, thereby remind the user to volatilize before exhausting in time filling electrolyte at original electrolyte.

In one embodiment, referring to FIG. 2, an indicator cavity 115 is also provided in the etalon housing 110. The indicating chamber 115 is provided with a marking member, and the liquid level indicator 150 extends into the indicating chamber 115 and is slidably fitted in the indicating chamber 115. For example, the identification member is a mark such as a graduation mark, a number, a pattern, and the like. Thus, through the comparison between the liquid level indicator 150 and the identification member in the indication cavity 115, the liquid level condition of the electrolyte in the accommodating cavity can be observed more clearly, and the testing efficiency is improved.

In one embodiment, referring to fig. 2, the circumferential sidewall of the piston 151 is provided with a first sealing member 153, and the first sealing member 153 is in sealing engagement with the circumferential inner wall of the accommodating chamber 111. The first seal 153 is, for example, a rubber packing. Therefore, the sealing effect between the piston 151 and the inner wall of the accommodating cavity is improved, air leakage is avoided, and the effects of vacuumizing and working of the liquid level indicator are influenced.

In one embodiment, referring to fig. 1 and fig. 2, the etalon housing 110 includes a first housing 116 and a second housing 117, the first housing 116 is detachably connected to the second housing 117, the accommodating cavity 111 is disposed in the first housing 116, and the evaporation cavity 112 and the evaporation hole 113 are disposed in the second housing 117. Thus, the production is convenient, which is beneficial to reducing the manufacturing cost, and the openable etalon cavity 110 facilitates the installation and maintenance of the piston 151, the reset piece 152 and the air-permeable membrane 130, which is beneficial to reducing the maintenance cost.

In one embodiment, referring to fig. 1 and 2, the etalon housing 110 further includes a second sealing member 118, the second sealing member 118 is disposed between the first housing 116 and the second housing 117, and the first housing 116 is in sealing engagement with the second housing 117 through the second sealing member 118. For example, the second seal 118 is a rubber seal. Thus, it is beneficial to improve the sealing effect when the first cavity 116 and the second cavity 117 are assembled, so as to avoid air leakage, and further improve the overall quality of the leak test standard 100.

In one embodiment, a leak testing system (not shown) includes leak testing equipment and a leak testing standard 100 of any of the above.

When the electrolyte leakage test is carried out on the tested workpiece such as the lithium ion battery, firstly, the standard cavity 110 with the volatilization holes 113 with corresponding sizes is selected according to the electrolyte content of the tested product and the sizes of the leakage holes, the electrolyte is filled into the containing cavity 111 through the filling piece 120, after the filling is completed, the volatilization holes 113 are communicated with the leakage test equipment, the electrolyte in the containing cavity 111 can be evaporated or volatilized and enters the leakage test through the volatilization holes 113 to be detected, the volatilization area of the electrolyte of the tested workpiece can be simulated by the cross section area of the containing cavity 111, and the sizes of the leakage holes in the tested workpiece can be simulated by the volatilization holes 113, so that the leakage condition of the electrolyte with stable and continuous speed can be conveniently obtained by selecting the proper model of the standard cavity 110, thereby providing the standard value for the leakage test for reference, and being beneficial to improving the accuracy and the reliability of the electrolyte leakage test of the tested workpiece such as the lithium ion battery.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that various changes and modifications can be made by those skilled in the art without departing from the spirit of the invention, and these changes and modifications are all within the scope of the invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A leak test standard, the leak test standard comprising:

the standard device comprises a standard device cavity, a test device and a test device, wherein the standard device cavity is provided with an accommodating cavity, an evaporation cavity and a volatilization hole, the accommodating cavity is communicated with the evaporation cavity, the evaporation cavity is communicated with the outside through the volatilization hole, the accommodating cavity is used for accommodating electrolyte, and the volatilization hole is used for being communicated with a leakage test device;

annotate the piece, annotate the piece set up in on the etalon cavity, just but annotate the piece open-close formula communicate in hold the chamber, annotate the piece be used for to hold the chamber and annotate electrolyte.

2. The leak testing standard according to claim 1, further comprising a gas permeable membrane disposed between the receiving chamber and the evaporation chamber, the gas permeable membrane configured to allow passage of gas and to exclude liquid.

3. The leak test standard according to claim 1, wherein the standard cavity further comprises an opening and a volatilization plate, the evaporation cavity is communicated with the outside through the opening, the volatilization plate is detachably connected to the wall of the opening, the volatilization hole is formed in the volatilization plate, and the evaporation cavity is communicated with the opening through the volatilization hole.

4. The leak testing standard according to claim 1, further comprising an evacuation member in openable and closable communication with the evaporation chamber, the evacuation member being adapted to be connected to a vacuum evacuation device for evacuating the evaporation chamber.

5. The leak testing standard according to claim 4, further comprising a liquid level indicator, a piston, and a reset member, wherein the piston is movably connected to the inner wall of the accommodating chamber, the liquid level indicator is connected to a side of the piston facing away from the evaporation chamber, the reset member is connected between the piston and the wall of the accommodating chamber, and the reset member is in reset engagement with the piston.

6. The leak testing standard according to claim 5, wherein the standard cavity is further provided with an indicating cavity, the indicating cavity is provided with a marking member, and the liquid level indicating member extends into the indicating cavity and is in sliding fit with the indicating cavity.

7. The leak testing standard according to claim 5, wherein the circumferential side wall of the piston is provided with a first seal in sealing engagement with the circumferential inner wall of the receiving cavity.

8. The leak testing standard according to any one of claims 1 to 7, wherein the standard cavity comprises a first cavity and a second cavity, the first cavity is detachably connected with the second cavity, the accommodating cavity is disposed in the first cavity, and the evaporation cavity and the volatilization hole are disposed in the second cavity.

9. The leak testing standard of claim 8, wherein the standard cavity further comprises a second seal disposed between the first cavity and the second cavity, the first cavity being in sealing engagement with the second cavity via the second seal.

10. A leak testing system comprising leak testing equipment and a leak testing standard according to any one of claims 1 to 9.