Leak detector for an integral gas leak detection process, and corresponding method
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- INFICON GMBH
- Filing Date
- 2026-01-16
- Publication Date
- 2026-07-30
Smart Images
Figure EP2026051086_30072026_PF_FP_ABST
Abstract
Description
[0001] Inficon GmbH
[0002] Bonner Straße 498
[0003] 50968 Cologne
[0004] Our reference: Cologne, 251897WO FK / sab 13 January 2026
[0005] Leak detection device for integral gas leak detection and corresponding procedure
[0006] The invention relates to a leak detection device and a leak detection method for detecting a gas leak in a test object.
[0007] Integral leak detection tests whether gas is escaping from a test object without locating the gas leak. In one method, the test object can be contained in a test chamber connected to a gas detector. The test object is pressurized with a test gas while the test chamber is evacuated, or the pressure inside the test chamber is at least lower than inside the test object. Alternatively, the test object can be connected to the gas detector and evacuated while the test chamber is pressurized with a test gas, such as ambient air. The test chamber can also be a test enclosure. Therefore, integral leak detection can only determine the presence of a leak without locating it.
[0008] Traditionally, integral leak testing is often performed using a mass spectrometer. The test chamber is evacuated with a forevacuum pump and / or a turbomolecular pump, and the mass spectrometer measures the proportion of the test gas in the analyzed gas mixture under vacuum. Measuring the test gas proportion is also known as partial pressure measurement. The test gas proportion is a measure of the leak rate of a leak in the test specimen. It is possible to measure an increase in the test gas partial pressure and use it as an indicator of a leak. If the increase, or rather the rate of increase (partial pressure increase per unit time), of the measured test gas exceeds a certain threshold, this serves as an indication of a leak. Alternatively, it would also be conceivable to detect and assess a decrease in the test gas proportion, for example, the test gas proportion within the test specimen.
[0009] In the accumulation principle, the total pressure rise is measured over a predetermined period, i.e., the increase or rate of rise (total pressure increase per unit of time) of the absolute pressure within the measuring volume, i.e., within the test chamber containing the pressurized test specimen. The test chamber is sealed. Alternatively, a decrease in total pressure can also be detected as an indication of a leak, for example, by observing the pressure within the pressurized test specimen. As soon as the pressure change, i.e., the increase or decrease in total pressure, exceeds a certain threshold, this is used as an indication of a leak.
[0010] From DE 10 2022 111 596 A1, it is known that for integral leak detection on a test specimen, gas extracted from the test specimen or a test chamber containing the test specimen is compressed into a compression volume at the outlet of a compressor pump, and the pressure increase of the gas pressure in the compression volume is measured with a gas pressure sensor. Leak detection is then carried out from the pressure increase in the conventional manner according to the accumulation principle.
[0011] German patent application DE 10 2021 119 256 A1 describes a leak detection device for combined integral and localizing leak detection. For integral leak detection, a gas pressure sensor is provided to perform integral leak detection by measuring the pressure profile in the gas measuring volume.
[0012] The invention is based on the objective of creating an improved leak detection device and an improved method for detecting a gas leak in a test object.
[0013] The leak detection device according to the invention is defined by the features of claim 1. The method according to the invention for detecting a gas leak is defined by the features of claim 10.
[0014] The leak detection device according to the invention has the following features for detecting a gas leak in a test specimen:
[0015] A test connection for the test specimen or a test chamber to accommodate the test specimen,
[0016] a gas line path connected to the test port, which has a valve for selectively closing the gas line path, wherein the gas line path has a vacuum pump such that the inlet of the vacuum pump is connected to the test port via the gas line path and the gas outlet of the vacuum pump is connected to the valve via the gas line path,
[0017] wherein the leak detection device has a pressure measuring device connected to the vacuum pump in such a way that the pressure measuring device receives information about the power consumption or the speed of the vacuum pump and wherein the pressure measuring device is configured to determine from the information about the power consumption or the speed of the vacuum pump a statement about the pressure applied at the test port.
[0018] It may be provided that the pressure measuring device is designed to detect a change in the power consumption or the speed of the vacuum pump and to determine a change in the pressure at the test port from the change in power consumption or speed.
[0019] The pressure at the test port, or a change in the pressure at the test port, can be determined from the power consumption using the following relationship:
[0020] As a first approximation, the relationship between the power output P of a vacuum pump, for example in the form of a turbomolecular pump (TMP), and the total pressure can be interpreted as a linear function. For a larger pressure range, a higher-order polynomial is recommended, where the constants depend on the pump and the geometry of the setup.
[0021] Po: Power loss of the vacuum pump due to mechanical friction or electrical losses
[0022] ci, C2... Cn : system-dependent constants
[0023] p: Total pressure
[0024]
[0025] or
[0026] Ppump = Po + ci p + C2 p^2 + ... + Cn p^n with n as a natural number greater than 2. It may be provided that the pressure detection device for integral leak detection is designed to detect the presence of a leak in a test object based on the pressure increase at the test port by evaluating the power consumption or the speed of the vacuum pump.
[0027] It may be provided that the vacuum pump is a compressor pump or a turbomolecular pump.
[0028] It may be provided that the pressure measuring device is designed to determine the pressure increase at the test port under the assumption that the change in power consumption is proportional to the change in pressure at the test port.
[0029] It may be provided that the pressure measuring device is designed to determine the resulting drop in the speed of the vacuum pump when the vacuum pump is switched off, e.g. by electrically switching off the power supply to the pump motor, and to determine the increase in pressure at the test port from the drop in speed.
[0030] It may be provided that the pressure measuring device determines the pressure increase at the test port under the assumption that the drop in the speed of the vacuum pump is proportional to the increase in pressure at the test port.
[0031] It may be provided that the vacuum pump is a turbomolecular pump of a mass spectrometric countercurrent gas leak detector, the inlet of which is connected to a mass spectrometer and to the test port.
[0032] It can be provided that the vacuum pump is a booster pump of a mass spectrometric countercurrent gas leak detector, wherein the booster pump evacuates the test port and its output is connected via a connecting line to the inlet of a turbomolecular pump evacuating a mass spectrometer, wherein the connecting line has the valve.
[0033] The inventive method for detecting a gas leak in a test specimen using a leak detection device of the type described above comprises the following steps:
[0034] Pumping a gas from a test chamber connected to the test port or from a test specimen connected to the test port using the vacuum pump while the valve is closed,
[0035] Determining information about the power consumption or speed of the vacuum pump,
[0036] Determining the pressure at the test port from the information obtained.
[0037] The method allows the change in power consumption during the operation of the vacuum pump to be determined, and from the change in power consumption, a change in pressure at the test port can be determined.
[0038] Furthermore, the method can be used to determine the drop in the speed of the vacuum pump after the vacuum pump is switched off, and from the drop in speed an increase in the pressure at the test port can be determined.
[0039] The information about the rotational speed can, for example, refer to information about a change in rotational speed, in which case a statement about the pressure is derived from the change in rotational speed. "Statement about the pressure at the test port" means that the pressure is to be estimated or determined. In the case of a test specimen connected to the test port, this is the pressure within the specimen. In the case of a test chamber connected to the test port, this is the pressure prevailing in the test chamber.
[0040] The invention thus makes it possible to determine the pressure at the test port without measuring it. A pressure sensor is therefore not required.
[0041] The following section provides a more detailed explanation of exemplary embodiments of the invention with reference to the figures. The figures show:
[0042] Fig. 1 shows a first embodiment in schematic view,
[0043] Fig. 2 shows a second embodiment in schematic view and
[0044] Fig. 3 shows a third embodiment in schematic view.
[0045] Fig. 1 shows a test chamber 11 in the form of a conventional vacuum chamber containing a test specimen pressurized with test gas. The test chamber 11 is connected to a test port 20, which leads into a gas line 22. Downstream of the test port 20, the gas line 22 comprises a vacuum pump 32 in the form of a compressor pump, a compression chamber 34, a valve 27, and a backing pump 16.
[0046] First, the test chamber 11 is evacuated using the pre-pump 16 with the valve 27 open. The vacuum pump 32 can also be used to assist the evacuation process. As soon as a pressure threshold in the test chamber 11 is undershot, the valve 27 is closed. The vacuum pump 32 compresses gas flowing from the test chamber into the compression volume 34. The internal pressure of the test specimen is greater than the internal pressure in the test chamber 11, so that test gas from the test specimen enters the test chamber 11 through a leak and is compressed from there into the compression volume 34 by the vacuum pump 32 via the connection 20 when the valve 27 is closed. A second valve 29, not shown in Fig. 1 but provided in the embodiment shown in Fig. 2, can be provided in the gas line 22 between the vacuum pump 32 and the test connection 20, or alternatively between the compression volume 34 and the vacuum pump 32.Valve 29 allows the vacuum pump 32 to be disconnected from the test port 20 when changing the test specimen or test chamber. Valves 27 and 29 allow the compression volume 34 to be closed.
[0047] The vacuum pump 32 is connected to a pressure measuring device 24 such that the pressure measuring device 24 receives information about the power consumption or rotational speed of the vacuum pump 32. For this purpose, the pressure measuring device 24 is electronically connected to the electronic control unit of the vacuum pump 32. The pressure measuring device, which may be a microcontroller or a computer with data storage and software, is configured to determine the pressure at the test port 20 from the information received from the vacuum pump 32 regarding its power consumption or rotational speed. This pressure reading may, for example, be an estimated value or information about whether the pressure is changing and, if so, how large or presumed the pressure change is.
[0048] If, for example, test gas from a leak in the test specimen enters the test chamber when valve 27 is closed, the pressure at the test port 20 increases. With increasing pressure, the power consumption of the vacuum pump 32 also increases. The pressure sensing device 24 detects the increase in power consumption and thus identifies a pressure increase and therefore a leak in the test specimen.
[0049] Alternatively, with valve 27 closed, the vacuum pump 32 can be deactivated, and the pressure sensing device 24 can be used to monitor the change in the vacuum pump's speed. If the pressure at the test port 20 increases due to a leak in the test specimen, the vacuum pump 32 experiences increased braking, resulting in a greater drop in speed than at lower pressure, i.e., when there is no leak in the test specimen. The pressure sensing device detects this increased drop in speed, for example, using threshold values, and derives information about the presence of a leak in the test specimen.
[0050] The pressure measuring device 24 thus enables an integral total pressure measurement of the pressure at the test port 20 with the valve 27 closed, and therefore of the pressure within the test chamber 11. Based on the accumulation principle, leak detection can therefore be carried out without the need for a separate pressure sensor.
[0051] The compression volume 34 has a housing with an inlet and an outlet, the inlet and outlet each being connected to a section of the gas pipeline 22. The housing of the compression volume 34 can have a larger cross-section than the pipeline of the gas pipeline 22, so that the compression volume 34 is larger than a section of the pipeline of the gas pipeline 22 of the same length. Furthermore, the compression volume 34 is smaller than the test specimen 11 or the test chamber 11 at connection 20.
[0052] The same applies to the embodiment shown in Fig. 2. In addition to the pressure measuring device 24 for integral measurement according to the accumulation principle, a mass spectrometric gas detector 12 is provided, which is evacuated via a turbomolecular pump 18 and a backing pump 16. The turbomolecular pump 18 and the backing pump 16 form a vacuum pump system 14. The outlet of the backing pump 16 is open to the atmosphere. The gas line 22 opens at its end opposite the connection 20 into a gas line 30 connecting the backing pump 16 and the turbomolecular pump 18. A further gas line 28 connects an intermediate connection of the turbomolecular pump 18 with a section of the gas line 22 arranged between the compression volume 34 and the valve 27. The gas line 28 has a further controllable valve 25.The controllable valve 27 and the controllable valve 25 form a locking device 26 with which the compression volume 34 can be shut off from the vacuum pump system 14.
[0053] With the embodiment shown in Fig. 2, it is possible, in integral leak detection according to the accumulation principle, to measure the gas pressure not within the test chamber or in the test specimen, but with a compressing vacuum pump 32 at the test port 20 and the pressure measuring device 24 connected to the compressor pump 32. The compressor pump 32, arranged between the test specimen or test chamber 11 and the compression volume 34, compresses the gas from the test specimen or test chamber 11 into a separate compression volume 34 when the sealing device 26 is closed. This increases the gas pressure rise by a factor of the volume ratio between the compression volume 34 and the volume within the test specimen or test chamber. The smaller the volume of the compression volume 34 and the more efficiently or strongly the compressor pump 32 compresses the gas, the greater the resulting pressure rise in the compression volume 34.
[0054] In the embodiment shown in Fig. 3, a test specimen 11 is connected to a test port 20, which is gas-conducting and connected to the inlet of a test specimen high-vacuum pump 32. The test specimen high-vacuum pump 32 is connected to a backing pump 16 via a test specimen line 22 and has a gas pressure measuring volume 34, which is gas-conducting and connected via a first part of the test specimen line 22 to the outlet 19 of the test specimen high-vacuum pump 32 and via a second part of the test specimen line 22 to the inlet of the backing pump 16. The test specimen high-vacuum pump 32 is connected to a pressure measuring device 24 corresponding to those of the embodiments in Figs. 1 and 2. An intermediate gas vacuum port 26 of the test specimen high-vacuum pump 16 is connected via a first gas line 58 to a detector high-vacuum pump 36. The detector high-vacuum pump 36 and the test object high-vacuum pump 32 are each conventional turbomolecular pumps.The inlet of the detector high-vacuum pump 36 is connected to the gas detector 12. The gas detector 12 is a mass spectrometer that is evacuated by the detector high-vacuum pump 36. The detector high-vacuum pump 36 is connected to the backing pump 16 via a connecting line 54. The arrangement shown in Fig. 3 is a countercurrent mass spectrometric gas leak detector in which the gas from the test specimen 11 enters the mass spectrometer 32 via the gas line 58 in a countercurrent flow.
[0055] A second gas line 56 connects the gas pressure measurement volume 34 to another intermediate gas connection of the detector high-vacuum pump 36. This second gas line 56 has a throttle 38 with a predetermined and, for example, adjustable gas conductivity. Gas can continuously flow from the gas pressure measurement volume 34 countercurrently through the detector high-vacuum pump 36 into the mass spectrometer 12 via the second gas line 56. While the first gas line 58 and the second gas line 56 are shown together in the embodiment depicted in Fig. 3, other embodiments not shown in the figures are conceivable, in which either the first gas line 58 is present without the second intermediate gas line 56, or in which the second intermediate gas line 56 is present without the first gas line 58.
[0056] A third gas line 60 connects the gas pressure measuring volume 34 to the other intermediate gas connection of the gas detector high-vacuum pump 36 and has a selectively closable valve V3. The gas pressure measuring volume 34 can be vented via valve V3 and the third intermediate gas line 60. The first gas line 58 has a selectively closable first shut-off valve VI. The second intermediate gas line 56 has a selectively closable second shut-off valve V2. The third intermediate gas line 60 has a selectively closable third shut-off valve V3. The second section of the test piece line 22, connecting the gas pressure measuring volume 34 and the backing pump 16, has a selectively closable fourth shut-off valve V4. The connecting line 54, connecting the detector high-vacuum pump 36 to the backing pump 16, has a selectively closable fifth shut-off valve V5.
[0057] The test specimen high-vacuum pump 32 separates the gas stream extracted from the test specimen 11 into lighter components, such as helium and / or hydrogen, which are mainly transported to the detector high-vacuum pump 36 and used for localizing leak detection (spray leak detection), while the majority of the air extracted from the test specimen 11 is transported to the gas pressure measurement volume 34 downstream of the test specimen high-vacuum pump 32. Due to the high compression between the intermediate gas vacuum port 46 and the outlet 19 of the test specimen high-vacuum pump 32, the test specimen high-vacuum pump 32 acts as a barrier to the air components.
[0058] The gas pressure measuring volume 34 is cyclically closed by switching at least one of the valves in the detector lines 22, 56, 60 connected to the gas pressure measuring volume 34, i.e., at least one of the valves V2, V3, or V4, preferably by switching the third valve V3. The inflowing air, compressed by the test specimen high-vacuum pump 32, increases the pressure in the gas pressure measuring volume 34 and the power consumption of the test specimen high-vacuum pump 32. This increase in power consumption is detected by the pressure measuring device 24. The increase in power consumption is proportional to the pressure increase, which in turn is proportional to the integral leakage of the test specimen 11. The intermediate gas vacuum port 46, which can also be referred to as the intermediate gas outlet, is continuously open and connected to the gas detector 12, more precisely to a first intermediate gas port of the detector high-vacuum pump 36.This allows for simultaneous localizing leak detection, in this case in the form of spray leak detection, according to the mass spectrometric countercurrent principle.
Claims
Claims 1. Leak detection device for detecting a gas leak in a test object, with a test port (20) for the test specimen or a test chamber (11) to receive the test specimen, a gas line path (22) connected to the test connection (20), which has a valve (27) for selectively closing the gas line path (22), wherein the gas line (22) has a vacuum pump (32) such that the inlet of the vacuum pump (32) is connected via the gas line (22) to the test port (20) and the gas outlet of the vacuum pump (32) is connected via the gas line (22) to the valve (27), characterized by that the leak detection device has a pressure measuring device (24) connected to the vacuum pump (32) in such a way that the pressure measuring device (24) receives information about the power consumption or the speed of the vacuum pump (32) and that the pressure measuring device (24) is designed to determine, from the information about the power consumption or the speed of the vacuum pump (32), a statement about the pressure applied to the test port (20).
2. Leak detection device according to claim 1, characterized in that the pressure detection device (24) is configured to detect a change in the power consumption or the speed of the vacuum pump (32) and to determine a change in the pressure at the test port (20) from the change in the power consumption or the speed.
3. Leak detection device according to claim 1 or 2, characterized in that the pressure detection device (24) is designed for integral leak detection based on the pressure increase at the test port (20) by evaluating the power consumption or the speed of the vacuum pump (32) in order to detect the presence of a leak in a test object based on the pressure increase.
4. Leak detection device according to one of the preceding claims, characterized in that the vacuum pump (32) is a compressor pump or a turbomolecular pump.
5. Leak detection device according to one of the preceding claims, characterized in that the pressure detection device (24) is configured to determine the pressure increase at the test port (20) under the assumption that the change in power consumption is proportional to the change in pressure at the test port (20).
6. Leak detection device according to one of the preceding claims, characterized in that the pressure measuring device (24) is designed to determine the resulting drop in the rotational speed of the vacuum pump (32) when the vacuum pump (32) is switched off and to determine the increase in pressure at the test port (20) from the drop in rotational speed.
7. Leak detection device according to the preceding claim, characterized in that the pressure measuring device (24) determines the pressure increase at the test port (20) under the assumption that the drop in the rotational speed of the vacuum pump (32) is proportional to the increase in pressure at the test port (20).
8. Leak detection device according to any of the preceding claims, characterized in that the vacuum pump (32) is a turbomolecular pump of a mass spectrometric countercurrent gas leak detector, the inlet of which is connected to a mass spectrometer and to the test port (20).
9. Leak detection device according to one of the preceding claims, characterized in that the vacuum pump (32) is a booster pump of a mass spectrometric countercurrent gas leak detector, wherein the booster pump evacuates the test port (20) and its output is connected via a connecting line to the inlet of a turbomolecular pump evacuating a mass spectrometer, wherein the connecting line has the valve (27).
10. Method for detecting a gas leak in a test specimen using a leak detection device according to one of the preceding claims, comprising the steps: Pumping a gas from a test chamber (11) connected to the test port (20) or from a test specimen connected to the test port (20) using the vacuum pump (32) while the valve (27) is closed, Determining information about the power consumption or speed of the vacuum pump (32), Determining a statement about the pressure at the test port (20) from the information obtained.
11. Method according to the preceding claim, characterized in that the change in power consumption during the operation of the vacuum pump (32) is determined and that a change in pressure at the test port (20) is determined from the change in power consumption.
12. Method according to one of the preceding claims, characterized in that the drop in speed of the vacuum pump (32) after switching off the vacuum pump (32) is determined and that an increase in pressure at the test port (20) is determined from the drop in speed.