Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • 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
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/202—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material using mass spectrometer detection systems
  • G01M3/205—Accessories or associated equipment; Pump constructions
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/4228—Leak testing of cells or batteries
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/202—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material using mass spectrometer detection systems
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/22—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators
  • G01M3/226—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators for containers, e.g. radiators
  • G01M3/229—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators for containers, e.g. radiators removably mounted in a test cell
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M2300/00—Electrolytes
  • H01M2300/0017—Non-aqueous electrolytes
  • H01M2300/0025—Organic electrolyte
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• the invention relates to a method for leak detection on a liquid-filled test object.
• test gas gets into the test chamber through a possible leak in the test object, from where it is fed to a sensor for detecting the test gas.
• a test gas such as helium
• methods are also known in which gases are used as test gas that are present in the test item are already included when the test object is brought into the test chamber. Active filling of the test item with test gas is then not necessary.
• the gas already contained in the test specimen when it is introduced into the foil chamber can be components of air, such as nitrogen, oxygen or carbon dioxide. Gases can also be used as test gas which contain or consist of aromas of a product contained in the test item, such as coffee aromas in the case of coffee. Another possibility is to use gases as test gas, which are generated by a product contained in the test item, such as a food. In the case of coffee, this can be CO2, which forms within a coffee package after a few hours.
• the invention deals with leak detection on a test item which is filled with a liquid and in which no gas present in the test item is available as test gas and which should or cannot be actively filled with a separate test gas.
• a test item which is filled with a liquid and in which no gas present in the test item is available as test gas and which should or cannot be actively filled with a separate test gas.
• batteries that are filled with electrolyte liquids, such as a lithium-ion battery filled with dimethyl carbonate as the electrolyte.
• the gas that has escaped is often detected with the aid of a gas detector.
• the test item is checked for leaks using the vacuum method.
• the test item is placed in a vacuum chamber to test for leaks. Gas that escapes into the vacuum chamber through a leak in the test item is continuously conveyed out of the vacuum chamber by the vacuum system.
• a suitable sensor is used to selectively detect the leakage gas in the vacuum system. If the pressure is low enough, it moves Leak gas sufficiently quickly through diffusion or molecularly free to the sensor.
• test specimens filled with a liquid refrigerant e.g. heat exchangers - for leaks.
• a liquid refrigerant is contained in the test item under excess pressure in order to maintain the liquid phase of the refrigerant.
• a sniffer probe is guided along the areas of the test item to be checked for leaks, which sucks in refrigerant that escapes from a leak and vaporizes it and feeds it to a gas detector.
• the sniffer probe sucks in air from the environment of the test object and absorbs any leakage gas that is selectively determined with a corresponding sensor and distinguished from the air components sucked in.
• the sniffer leak detection method cannot be used because, in the event of a leak, no leak gas escapes to the outside.
• a leak no leak gas escapes to the outside.
• batteries that are filled with a liquid electrolyte with low vapor pressure and in which there is negative pressure air from the outside environment of the test object penetrates into the interior of the test object in the event of a leak. The leak cannot be detected with the help of a sniffer probe.
• the above-described leak detection methods using a test gas contained in the test piece are also not applicable or at least imprecise, because the liquid in the test piece gets into the opening or the channel of the leak when the external environment of the test piece is evacuated and prevents or at least significantly prevents the leakage of a test gas impaired. An amount of test gas recorded outside the test item is then no longer representative of the presence or size of a leak in the test item.
• EP 1 522 838 B1 describes a method in which a test item filled with an electrolyte is contained in a test chamber, the internal pressure of which is lower than the pressure within the test item. Purified air or ambient air is fed to the test chamber as a carrier gas in order to feed liquid components emerging from the test object to a detector using the carrier gas method.
• the invention is based on the object of providing a leak detection method for a liquid-filled test specimen whose internal pressure is less than or equal to atmospheric pressure.
• a test specimen filled with a liquid is introduced into a test chamber.
• the liquid is contained inside the test item.
• the Internal pressure inside the test object is less than or equal to atmospheric pressure.
• the test chamber is evacuated to a pressure below the internal pressure in the test specimen and below atmospheric pressure. Residual gas components that are contained in the test chamber are sucked off together with gas components desorbing from at least one test chamber wall and possible parts of the liquid that leak from the test object into the test chamber and fed to a detector without a carrier gas being fed to the test chamber becomes. Parts or particles of the liquid emerging from the test piece are selectively detected with a detector.
• the test chamber is not supplied from the outside with any carrier gas which, for example, comes from a carrier gas source connected to the test chamber or is taken from the environment of the test chamber.
• a carrier gas source connected to the test chamber or is taken from the environment of the test chamber.
• a carrier gas is not required.
• the parts of the liquid that have escaped from the leak can be molecular particles in vaporized form.
• the evaporation can take place when exiting the test item.
• the liquid evaporates at the outlet of the leakage channel, which runs through the leaky wall of the test object.
• the liquid can have a vapor pressure that is less than 500 mbar at room temperature (approx. 15 ° C to 25 ° C).
• the test item can be a battery, such as a lithium-ion battery, and the liquid can be an electrolyte, such as dimethyl carbonate.
• the test chamber can be designed as a rigid test chamber with rigid walls.
• the test chamber can also be designed as a film chamber, which is characterized in that it has at least one flexible wall area that is sucked onto the test object during evacuation and reduces the volume of the film chamber.
• film chambers in particular with walls consisting entirely of a flexible film, offer the advantage that the walls sucked onto the test object support the test object, which is particularly advantageous in the case of a flexible test object.
• the detector has a sensor which selectively detects the parts or particles of the liquid to be detected and can thereby distinguish them from other parts or gases.
• the parts of the leaked liquid can be in liquid form and fed to the detector.
• the detector must be able to analyze liquids and selectively detect the liquid contained in the test item.
• the leaked liquid can be fed to the detector in the form of a mist or aerosol, for example.
• the detector must then be designed as a gas detector and be able to analyze gases and selectively differentiate the gaseous phase of the liquid in the test object from other gases.
• the decisive factor here is that the liquid contained in the test item only changes from the liquid phase to its gaseous phase when it leaves the test item, i.e. outside the test item or in the opening or channel of the leak. No gas present in the test item is used as the test gas because the liquid is in liquid form within the test item, even if the liquid leaks out and evaporates in the process.
• the detector for the parts of the liquid to be detected can be a gas detector, such as a mass spectrometer, a gas chromatograph, an infrared radiation absorption detector or a detector with chemical sensors or semiconductor sensors.
• the test chamber is not supplied with a constant flow of carrier gas, as is the case with conventional carrier gas methods for gas leak detection. Rather, the residual gas constituents within the test chamber and the gas constituents desorbing from the test chamber walls are used to transport parts or particles of the liquid that have entered the test chamber from a leak in the test chamber to the detector. A mixture of gas components from the interior of the test chamber or from the test chamber walls and from parts or particles of the liquid contained in the test piece is fed to the detector and analyzed with the aid of the detector in order to detect the parts of the liquid transported with the gas.
• the gas stream transporting the parts of the liquid is preferably only fed to the detector when a pressure limit value is reached in the test chamber or in the connecting line between the test chamber and the vacuum pump sucking off the test chamber.
• This pressure limit value can be between approximately 2 mbar and 50 mbar and is preferably less than 20 mbar.
• the vacuum pump which is preferably a membrane pump, can be connected via a valve to the test chamber and / or to the gas line connecting the vacuum pump and the test chamber. When the test chamber is evacuated, the valve is closed. When the pressure limit is reached, the valve is opened and a partial flow reaches the detector, while the remaining main gas flow continues to be sucked off with the membrane pump.
• test specimen is flushed with a flushing gas in the test chamber in order to remove parts of the liquid adhering to the test specimen.
• the test object is preferably flushed with flushing gas before the actual leak detection takes place, e.g. before the test chamber is evacuated.
• Calibration can take place with the aid of a test leak that is filled with a test liquid.
• the test leak can be designed as a capillary leak in which the test liquid emerges through a capillary with known dimensions that is formed in the wall of the test leak.
• the test leak can be a permeation liquid leak in which a region of the wall of the test leak is designed as a membrane with known permeation properties for the test liquid.
• Fig. 1 is a block diagram of a first embodiment
• FIG. 2 shows a block diagram of a second exemplary embodiment.
• a test specimen 14 filled with a liquid 12 is contained in a test chamber 16.
• the test item 14 is a battery which is filled with a liquid electrolyte.
• the test chamber 16 is a conventional rigid test chamber in the present exemplary embodiments.
• the test chamber 16 is provided with a vacuum connection 22 to which a vacuum pump 24 is connected, with which the test chamber 16 can be evacuated.
• the vacuum pump 24 has at least one vacuum pump in the form of a membrane pump.
• the test chamber 16 and the vacuum pump 24 are connected to one another in a gas-conducting manner by a connecting line 26, so that the vacuum pump 24 can suck gas out of the test chamber 16 via the connecting line 26.
• a detector 28 for analyzing and detecting parts of the liquid 12 is connected to the connecting line 26 connecting the vacuum pump 24 to the test chamber 16.
• the detector 28 is a selective gas detector, for example in the form of a mass spectrometer, the sensor of which selectively detects molecular particles in the liquid 12 and can distinguish them from other gases.
• the detector 28 is part of a mass spectrometric vacuum system 20 which has a backing pump 19 and a high vacuum pump 18 for evacuating the mass spectrometer 28.
• the detector 28 is connected in a gas-conducting manner to the connecting line 26 via a gas-conducting detection line 21.
• the detection line 21 is provided with a throttle 38 for throttling the gas flow branched off from the connecting line 26 and with a valve V2 for selectively closing the detection line 21.
• a throttle 38 for throttling the gas flow branched off from the connecting line 26
• a valve V2 for selectively closing the detection line 21.
• Parts of the liquid 12 escape from a leak in the test item 14 and enter the test chamber 16. When the liquid 12 emerges from the test item 14, it can evaporate so that the leaked parts of the liquid 12 can be in gaseous form.
• the detector 28 is operated as a mass spectrometer in the vacuum system 20 with a pressure which is lower than the pressure within the test chamber 16 and lower than the pressure at the connection point 40 between the connecting line 26 and the detection line 21.
• the membrane pump 24 used according to the invention for suctioning off the test chamber 16
• no high vacuum is generated within the test chamber 16.
• the diaphragm pump 24 generates a pressure in the range of a few millibars.
• the membrane pump 24 sucks residual gas components still present from the test chamber 16.
• gas components desorb from the walls of the test chamber, which are also sucked off by the membrane pump 24.
• These gas constituents i.e. residual gas constituents from the test chamber 16 and gas constituents desorbing from its walls, absorb parts of the liquid 12 which leak from the test object 14 into the test chamber 16. These parts of the liquid 12 are fed to the detector 28.
• the vacuum pressure within the test chamber 16 after evacuation is a few millibars.
• the diffusion of the parts of the liquid 12 that have emerged from the test specimen 14 and evaporated is still sluggish at this pressure.
• the Transport of the leaked parts of the liquid 12 to the detector 28 is accelerated with the gas components without a carrier gas being used and being supplied to the test chamber 16 from the outside.
• valve V2 can be opened for detection. During the accumulation phase, the valve V2 can be closed or open.
• the second embodiment shown in FIG. 2 differs from the first embodiment according to FIG. 1 in that the section 30 of the detection line 21 having the valve V2 is bridged by a section 36 having a further valve V3, so that the valves V2, V3 are parallel are switched.
• a valve VI is provided between the connection point 40 of the connecting line 26 with the section 30 and the connection point 42 between the connecting line 26 and the section 36.
• the valve VI is open.
• the valve V2 is then closed.
• the detector 28 of the second exemplary embodiment is also a mass spectrometer with an independent vacuum system.
• the inlet area to the mass spectrometer is also via the vacuum pump 24 evacuated.
• valve V 2 remains closed, while valve VI is closed and valve V3 is opened in order to evacuate the inlet area to the mass spectrometer to the required vacuum pressure.
• valve VI is closed for measuring operation and valves V2 and V3 are opened so that the measuring medium is transported from test chamber 16 past detector 28 via vacuum pump 24.
• the liquid 12 contained in the test specimen 14 enter the test chamber 16.
• the liquid can be dimethyl carbonate, which is used as an electrolyte in a lithium-ion battery.
• a vacuum pressure prevails in the lithium-ion battery which is greater than the pressure inside the test chamber 16 in the area outside the test object 14, after which the test chamber 16 was evacuated.
• the liquid electrolyte evaporates as it exits the test item 14 through a leak, so that the parts of the liquid 12 to be detected can be present in the form of molecular particles in a gaseous phase.
• the parts of the liquid 12 are transported through the test chamber 16 and via the lines 26, 30, 21 into the detector 28, and passed on to the pump 24 via the line 36.
• This forms a mixture of gas components that originate from the interior of the test chamber 16 and / or from the walls of the test chamber 16 and transported parts of the liquid 12.
• the selective sensor of the mass spectrometric detector 28 detects the parts of the liquid 12 and is in the Able to distinguish this from the gas components of the test chamber 16.
• the detection of the parts of the liquid 12 which has leaked from the leak in the test specimen 14 serves as an indication of the presence of a leak in the test specimen.
• the size of a leak can be inferred from the amount of detected parts of the liquid 12.
• the parts of the liquid 12 emerging from a leak in the test object 14 can accumulate within the test chamber 16 before the Detection takes place.
• the valves VI, V3 are closed during the accumulation phase.
• valve V2 can also be closed during the accumulation phase. After a predetermined time has elapsed, the valve V2 is opened so that the accumulated parts of the liquid 12 are fed to the detector 28.
• the accumulated gas can also be transported from the test chamber 16 to the detector 28 by the gas components after the accumulation phase. For this purpose, no carrier gas is supplied from the outside to the evacuated test chamber 16.
• the test chamber 16 is closed, there is a wait until parts of the liquid 12 have accumulated in the test chamber 16 within a predetermined period of time.
• the detector 28 is brought to a lower pressure than the pressure prevailing in the test chamber 16 with the aid of the vacuum pumps 18, 19.
• the valve V2 is opened, the accumulated parts of the liquid 12 are transported to the detector 18 and detected there.
• the conductance of the throttle 38 and the threshold value of the pressure before (on the left in the figures) the throttle 38, at which the valve V2 is opened, are selected such that the gas inlet via the throttle 38 into the chamber volume of the mass spectrometer 28 does not have a pressure increase causes more than 10 4 mbar.
• the pressure threshold value is preferably approximately 5 mbar under laboratory conditions.
• a signal is generated on a measurement mass that is characteristic of a characteristic component of the liquid 12 (electrolyte component).
• the measurement signal is compared with a threshold value, and if the threshold value is exceeded, a leak in the test item 14 is considered to be present.
• the valve V2 is closed, the test chamber is ventilated and, if necessary, the test item 14 is removed from the test chamber 16.
• the method according to the invention does not require a high-quality vacuum pump for evacuating the test chamber 16, such as a high vacuum pump, but only a simple vacuum pump, such as a diaphragm pump, which can achieve a final pressure of less than 10 mbar.
• An essential difference between the two exemplary embodiments is that, in the exemplary embodiment in FIG. 2, after closing valve VI and opening valves V2, V3 after falling below the specified pressure threshold, a shorter path has to be covered from throttle 38 to mass spectrometer 28, than in the embodiment in FIG. 1.
• the pressure within the detection line 21 is low, namely less than 10 4 mbar, so that molecular free movement conditions for the gas exist in this area. The duration of the propagation of the gases up to the mass spectrometer 28 is thus negligible.
• the pressure within the lines 26, 30, 32, 36 is, for example, 5 mbar. Viscous flow conditions prevail, as a result of which the measuring gas has to diffuse through residual gas along this route, which causes a time delay.
• this diffusion path is longer from the connection point 40 between the connecting line 26 and the vacuum line 21 to the throttle 38 than the diffusion path in FIG. 2 between the connection point 44 of the lines 30, 36, 21 and the throttle 38.

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Citations (6)

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• 2019
  • 2019-08-08 DE DE102019121462.9A patent/DE102019121462B4/de not_active Expired - Fee Related
• 2020
  • 2020-07-17 TW TW109124216A patent/TWI868181B/zh active
  • 2020-07-22 WO PCT/EP2020/070661 patent/WO2021023513A1/de not_active Ceased
  • 2020-07-22 CN CN202080037062.3A patent/CN113853517A/zh active Pending
  • 2020-07-22 JP JP2021559388A patent/JP7535059B2/ja active Active
  • 2020-07-22 US US17/436,986 patent/US12315892B2/en active Active
  • 2020-07-22 EP EP20745164.2A patent/EP3894821B1/de active Active
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