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
  • G01M3/04—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
• • 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
  • 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
  • G01M3/34—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 testing the possibility of maintaining the vacuum in containers, e.g. in can-testing machines

Definitions

• the invention relates to a device and a method for leak detection of a test piece containing a test gas.
• test specimens such as food packaging, heat exchangers or other hollow bodies that contain a test gas
• test specimens for leaks by placing the specimen in a test chamber and evacuating the volume of the test chamber by a vacuum pump.
• tracer gas escapes through a possible leak in the test piece and is evacuated by the vacuum pump.
• the gas flow evacuated by the vacuum pump is examined by a gas detector that detects test gas.
• classic helium vacuum leak detection the test object is filled with helium, with the test object being at atmospheric pressure or at a pressure greater than atmospheric pressure.
• the test chamber is typically pre-evacuated before a backing pump and then evacuated by a turbomolecular pump to a maximum pressure of a few millibars during the leak measurement. Tracer gas escaping from a leak in the test object results in a tracer gas concentration of the gas pumped from the test chamber, which is detected by the detector. The test gas concentration or the test gas partial pressure serves as a measure for the leak rate in the test object. At a working pressure within the test chamber of well below 1 mbar, the diffusion speed of the gases is sufficiently high that test gas escaping from the test object reaches the sensor system of the gas detector without any significant time delay.
• the invention is based on the object of providing a more cost-effective vacuum leak detection system and a more cost-effective method for vacuum leak detection, which enables rapid and homogeneous gas transport and thus rapid and reproducible test gas detection.
• a test chamber provided with a plurality of vacuum connections is connected to a vacuum pump, with a gas detector being used to detect test gas in the evacuated gas flow.
• a vacuum connection is understood to mean an opening in a wall, a floor and/or a cover of the test chamber, through which gas can pass from the interior of the test chamber into a volume connected to the vacuum connection.
• At least several of the vacuum connections and preferably all of the vacuum connections are connected to a common pump volume into which the vacuum connections open.
• the pump volume is over a Pump line connected to the vacuum pump.
• the gas detector can be connected to the pump line.
• the vacuum connections are formed in at least one wall, base and/or cover of the test chamber delimiting the test chamber volume and are distributed as evenly as possible.
• the vacuum connections are designed in such a way that during operation during the evacuation of the test chamber with the vacuum pump, a lower vacuum pressure develops in the pump volume than in the test chamber.
• the common pump volume results in a higher flow rate of the pumped gas than inside the test chamber.
• the leakage gas from a leak reaches the detector, it is less dependent on the position of the leak on a test object in the test chamber and thus the dependence on the position of the test object itself in the chamber is reduced.
• the signal strength measured by the test system at a given point in time when there is a leak on the test object is less dependent on the position of the test object in the test chamber.
• the vacuum leak detection according to the invention does not require a high-vacuum pump or a high-vacuum pump like conventional, classic vacuum leak detection methods Turbomolecular vacuum pump, but can instead be operated with technically simpler, more cost-effective vacuum pumps, such as a membrane scroll or rotary vane pump. As a result, the vacuum leak detection according to the invention is technically simplified and more cost-effective.
• the vacuum connections can be distributed evenly, for example homogeneously, over at least one wall, base and/or cover delimiting the inner volume of the test chamber.
• Several walls, the base and/or the cover are preferably each provided with several vacuum connections.
• the vacuum connections can each be arranged in a grid, for example in the manner of a grid.
• the test chamber volume can be formed within one or more of the test chamber walls, the test chamber floor and/or the test chamber cover, for example by a double floor or a double wall forming the pump volume.
• vacuum connections can be connected to the pump volume with lines of substantially the same length.
• the same length means that the differences in length of the vacuum lines are less than 10% of the total length of one of the vacuum lines.
• the invention makes it possible, with a comparatively technically simple and comparatively inexpensive vacuum pump system, to nevertheless enable rapid vacuum leak detection by rapid and uniform gas transport of the pumped gas.
• This is achieved by the pumping volume connected to the vacuum ports, where the difference in pressure at any location within the test chamber and the pressure at any location in the pumping volume is greater than the difference between the pressures at two different locations within the test chamber.
• the gas pressure gradient extending over the distance from a location within the test chamber to a location within the pumping volume is greater and preferably significantly greater than the pressure gradient between any points within the test chamber.
• the pressure distribution within the test chamber should be as homogeneous as possible, so that the pressures at different locations within the test chamber in the area outside the test object differ by a maximum of 1%, while the gas pressure at any location within the pump volume is significantly lower than the pressure at any one location within the test chamber.
• the pressure at a location within the pump volume is at least 10% lower than at a location within the test chamber.
• the pressure inside the test chamber is preferably less than 80, preferably less than 40, and more preferably less than 20 mbar, while the pressure inside the pump volume is preferably less than 72, preferably less than 36, and more preferably less than 18 mbar.
• FIG. 1 shows a schematic representation of a first exemplary embodiment
• Fig. 2 is a schematic representation of a second embodiment
• FIG. 3 shows a schematic representation of a third exemplary embodiment.
• a test chamber 12 is connected to a vacuum pump 18 via a pump line 14 to which a gas detector 16 is connected.
• the vacuum pump 18 can be a membrane, scroll or rotary vane pump.
• the test chamber is typically formed by a plurality of walls 20, a cover 22 and a floor 24.
• the Figs. 1 and 2 each show the test chamber 12 in an open position State while the lid 22 is closed gas-tight in the direction of the arrows shown.
• the cover 22 is provided with a plurality of vacuum connections 26, which are arranged in a grid and distributed homogeneously over the entire inside of the cover 22.
• the vacuum ports 26 are formed as holes, shown as dots in the figures.
• the vacuum connections 26 open into a common pump volume 28, which is designed as a cavity in the cover 22 and is connected to the vacuum pump 18 via the pump line 14.
• Fig. 3 differs from that in Figs. 1 and 2 in that both the cover 22 and all of the walls 20 and the bottom of the test chamber 24 are each provided with a plurality of vacuum connections 26, which are also shown in simplified form as dots.
• Each of the vacuum connections 26 is connected to the pump volume 28 via a separate vacuum line 30 , which opens into the pump line 14 .
• the pump volume 28 can also be a section of the pump line 14 .
• the pressure inside the test chamber 12 is reduced to 80 mbar, preferably less than 40 mbar and particularly preferably less than 20 mbar, with the aid of the vacuum pump 18.
• the pressure inside the test chamber is preferably less than 72, preferably less than 36, and particularly preferably less than 18 mbar.
• test gas from within the device under test will exit through the leak into the test chamber 12 and be drawn into the pumping volume 28 through at least one of the vacuum ports 26 .
• the test gas Due to the With several vacuum connections 26, the test gas only has to travel a comparatively small distance within the test chamber until it reaches the pump chamber 28 through the vacuum connection 26 that is closest in each case.
• the relative distance of each location within the test chamber to the nearest vacuum connection 26 is reduced with the multiple vacuum connections 26 according to the invention.
• the deviation of the period of time that elapses from the emergence of a leaking gas until it reaches the detector is smaller for different locations of a leak within the test chamber than in the case of only one vacuum connection. The variance of this period of time is therefore lower for any different locations of a leak within the test chamber than in the case of just one vacuum connection.
• the test gas As soon as the test gas has flown through the vacuum connection 26, the test gas is accelerated in the pump volume 28 due to the lower pressure or the lower gas density.
• the diffusion speed or the flow speed of the pumped gas is greater in the pump volume 28 and in the pump line 14 than in the test chamber 12.
• a gas pressure gradient that is less than the gas pressure gradient that develops along the route from a point within the test chamber 12 to a point within the pumping volume 28 develops along a distance between any different points within the test chamber 12 .

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Examining Or Testing Airtightness (AREA)

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Publications (1)

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Family Applications (1)

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• 2021
  • 2021-10-04 DE DE102021125707.7A patent/DE102021125707A1/de active Pending
• 2022
  • 2022-09-12 JP JP2024518613A patent/JP2024535384A/ja active Pending
  • 2022-09-12 KR KR1020247007985A patent/KR20240087676A/ko active Pending
  • 2022-09-12 CN CN202280062952.9A patent/CN118076869A/zh active Pending
  • 2022-09-12 WO PCT/EP2022/075305 patent/WO2023057173A1/de not_active Ceased
  • 2022-09-12 EP EP22782489.3A patent/EP4413345A1/de active Pending
  • 2022-09-12 US US18/693,119 patent/US20250130133A1/en active Pending

Patent Citations (2)

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