Apparatus and method for detecting leaks

Abstract

To provide means enabling the highest possible test gas sensitivity during control operation, and capable of evacuating a detector as quickly as possible in a case of test gas contamination.SOLUTION: At least one bypass 27, 28 is provided for test gas 21. The bypass leads from a bypass outlet 29 toward the outside of a turbopump region, which is located at the height of a test gas inlet 25 or upstream of the test gas inlet, directly to a detector 19 or to a bypass inlet 31 toward the inside of the turbopump region, which is located upstream of the bypass outlet, and at that time, the bypass bypasses at least some parts 17a, 18b, 18c of the turbopump region.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a device for detecting leaks according to a vacuum method based on the countercurrent principle, comprising: a vacuum pump unit having a turbo vacuum pump which can be connected to a test object to be evacuated and comprises a turbo pump region formed by one or more turbo pump stages; and a detector for detecting a test gas, particularly helium, particularly a mass spectrometer, wherein the turbo vacuum pump is connected to the detector via at least one axial and / or radial suction port, has a test gas inlet on a downstream side of the suction port, and at least a part of the turbo pump region is located between the suction port and the test gas inlet in a pumping direction of the turbo vacuum pump.

[0002] Furthermore, the present invention relates to a method for inspecting leaks according to a vacuum method based on the countercurrent principle using a leak inspection device, particularly the leak inspection device disclosed herein, wherein the leak inspection device comprises a vacuum pump unit and a detector, the vacuum pump unit can be connected to a test object to be evacuated and has a turbo vacuum pump comprising a turbo pump region, and the turbo pump region is formed by one or more turbo pump stages. [Background Art]

[0003] The term "turbo..." as used herein is employed as an abbreviation for "turbomolecular..." for the sake of simplicity within the scope of the present disclosure. That is, for example, when reference is made to a turbo vacuum pump or a turbo pump stage, this is to be understood as a turbomolecular pump or a turbomolecular pump stage.

[0004] The concept of leak detection following the vacuum method based on the countercurrent principle is fundamentally known in vacuum technology. The object of test is the component itself, also called the "test specimen," which is to be actually tested. This assumes that this component can be evacuated to a certain vacuum pressure, or the object of test is the vacuum chamber in which the component to be tested is located. In the latter case, it is the vacuum chamber, not the component itself, that is evacuated. In both cases, the detector detects the test gas located inside the vacuum chamber; specifically, the test gas is measured and expressed, for example, as the so-called leak rate.

[0005] Various leak detectors, especially helium directors, are generally known to specialists. The countercurrent principle and the countercurrent leak detectors used therein, as mentioned here, also belong to the field of expertise in vacuum technology. For this, refer in particular to the 11th edition of "Wutz Handbuch Vakuumtechnik (Hrsg. Karl Jousten)" in Springer Vieweg, and specifically to Chapters 14.4 "Leckdetektoren", 19 "Lecksuchtechniken", and 19.4 "Lecksuchverfahren mit Heliumleckdetektoren".

[0006] In principle, the goal is to achieve the highest possible sensitivity in the leak detection device; that is, more test gas (per unit of time) should be able to flow towards the detector. Therefore, the requirement for the type of leak detection device described herein is the largest possible amount of test gas backflow through the turbopump region located upstream of the test gas inlet. Thus, in control operation, i.e., during leak detection (also referred to here as the "test mode" of the leak detection device), it is essentially advantageous for the relevant portion of the turbopump region to have a relatively low compression and relatively low pumping speed for the test gas, provided that it is ensured that the turbovacuum pump can maintain the low pressure required in the detector during the test mode.

[0007] However, it must be noted that, in practice, so-called "test gas contamination" of the detector can occur, especially when there is a relatively large leak in the test object. In this case, the detector must first be evacuated, that is, the test gas must be discharged from the detector, and then the detector is ready for operation again for further leak detection. For this discharge process (also referred to here as the "vacuum evacuation mode" of the leak detection device), high compression of the test gas and the resulting high exhaust speed are aimed for in the turbopump range.

[0008] Therefore, given this background, conflicting requirements arise in practice between leak detection devices and, in particular, the turbopump region of turbo vacuum pumps. Specifically, the turbopump region, which is advantageous in the case of test gas contamination and is optimized for high pumping speed and high compression, allows for relatively little test gas backflow, which hinders the requirement for the detector to be as sensitive as possible to the test gas during the test mode, i.e., during control operation. [Prior art documents] [Non-patent literature]

[0009] [Non-Patent Document 1] “Wutz Handbuch Vakuumtechnik(Hrsg. Karl Jousten)” 11th edition, Springer Vieweg [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] Therefore, the object of the present invention is to provide a means that enables the highest possible sensitivity to the test gas during control operation and allows the detector to be evacuated as quickly as possible in the event of test gas contamination. [Means for solving the problem]

[0011] This problem is solved by the features of each independent claim.

[0012] The leak detection device according to the present invention is provided with at least one bypass for the test gas, the bypass being located at the height of the test gas inlet or upstream of the test gas inlet, and leading from a bypass outlet that exits the turbopump area directly to the detector or to a bypass inlet located upstream of the bypass outlet that enters the turbopump area, while bypassing at least a portion of the turbopump area.

[0013] Preferably, the bypass is provided with an adjustment device that changes the conductance of the test gas, and the adjustment device is controllable by the device's control unit, thereby changing the conductance between a relatively high value and a relatively low value depending on the operating status of the device.

[0014] The method for detecting leaks according to the present invention is characterized by providing at least one bypass for the test gas that is generated in the test object, reaches the turbo vacuum pump, and flows to the detector in the opposite direction to the pumping direction, wherein the bypass bypasses at least a portion of the turbo pump area and goes directly to the detector or returns to the turbo pump area.

[0015] Preferably, during the operation of the leak detection device, the conductance of the bypass with respect to the test gas is changed from a relatively high value in the test mode in which the test gas is detected by the detector to a relatively low value in the vacuum evacuation mode in which the detector is evacuated.

[0016] The bypass allows the test gas to bypass at least a portion of the turbopump region. Therefore, at least this portion of the turbopump region can be optimized to achieve the highest possible compression and exhaust speed, without compromising the detector's sensitivity to the test gas during control operation. In this case, if test gas contamination occurs, the relatively high compression and the resulting high exhaust speed force advantageously allow the test gas to be discharged from the detector relatively quickly.

[0017] For this operation, also referred to herein as the vacuum evacuation mode, the bypass conductance can be reduced, i.e., to a relatively low value, but this is not mandatory.

[0018] It is possible to implement a bypass for the test gas, and it has been found that the conductance of the bypass with respect to the test gas does not need to be reduced for the vacuum evacuation mode. The conductance of the bypass can be kept constant, and in this case, no undesirable "short-circuit effect" occurs in the vacuum evacuation mode, that is, the test gas discharged from the detector is not returned to the detector through the bypass to an undesirable extent. Such particularly passive bypasses, i.e., bypasses whose conductance with respect to the test gas cannot or does not change, may have, for example, a capillary or a selection device such as a selection diaphragm. A gas conduit in the form of a capillary has a higher conductance for lighter gases, especially helium, than for heavier gases, especially nitrogen or air, or such a selection diaphragm is passable for the test gas, especially helium, but not for external gases heavier than the test gas, especially nitrogen.

[0019] Therefore, the bypass concept according to the present invention meets the conflicting requirements for leak detection devices mentioned at the beginning. At the same time, high test gas sensitivity of the detector during control operation and rapid recovery of the detector's operational readiness in the event of test gas contamination of the detector are achieved.

[0020] Whether the test gas reaches the detector directly via a bypass during control operation, or first returns to the turbopump region, depends particularly on the specific form of the turbovacuum pump and / or the arrangement of the turbovacuum pump relative to the detector. This will be discussed in more detail elsewhere, in relation to the illustrated embodiment. When the turbovacuum pump has only one axial intake port relative to the detector, for example, a radial bypass outlet may be located between two turbopump stages, and the bypass may lead directly to the detector. When the vacuum pump is configured and arranged to have multiple radial intake ports relative to the detector, or one axial intake port and at least one radial intake port, the bypass may allow the test gas to bypass a portion of the turbopump region and then return to the turbopump region, from where the test gas reaches the detector.

[0021] In both cases, the turbo vacuum pumps may each be configured as so-called split-flow vacuum pumps. The radial intake of the split-flow vacuum pump may be connected to the exhaust port of the valve unit of the vacuum pump unit, regardless of whether the split-flow vacuum pump is connected to the detector by one or more radial intakes or by axial intakes only, as disclosed elsewhere.

[0022] In this specification, the terms “downstream” and “upstream,” as used in particular in relation to the locations of the test gas inlet, bypass outlet and bypass inlet, and the locations of the turbopump stages, refer, unless otherwise specified within the scope of this disclosure, to the pumping direction of the turbovacuum pump of the vacuum pump unit, and consequently to the rotation axis of the rotor of the turbovacuum pump.

[0023] The term "directly to the detector" applies when the bypass is not returned to the turbopump region. This does not exclude that in some possible embodiments, the bypass may extend through one or more other devices before opening into the detector, or may lead into a chamber in a housing of a device arranged upstream of the detector, for example a leak detection device, from which the test gas then proceeds to the detector.

[0024] Further embodiments of the present invention are also described in the dependent claims, the description and the drawings.

[0025] At least two bypasses may be provided for the test gas. The bypasses may exit the turbopump region at different locations and / or lead directly to the detector at different locations, or may first be returned to the turbopump region. The sensitivity of the detector can be further increased by means of one or more additional bypasses.

[0026] The plurality of bypasses may be designed such that portions of the turbopump region having different levels of compression and / or different pumping speeds are bypassed.

[0027] Furthermore, when an adjusting device is provided, it can be contemplated that the conductance of the bypasses is changeable independently of each other.

[0028] The turbopump region preferably has a plurality of turbopump stages arranged consecutively in the pumping direction. As a whole, the turbopump region has a plurality of alternating rotor blades and stator blades, the rotor blades and stator blades being arranged at a predetermined axial spacing, wherein the term "axial direction" applies to the rotation axis of the rotor of the turbomolecular vacuum pump coupled to the rotor blades, and thus to the pumping direction of the turbomolecular vacuum pump. Referring to individual turbopump stages, individual turbopump stages can be defined relative to one another in that the axial spacing between two turbopump stages is greater than the axial spacing between the rotor blades or stator blades within each respective turbopump stage.

[0029] Regarding the location of the test gas inlet, it may be intended to be located at the height of one turbopump stage, or downstream of one turbopump stage, particularly between two turbopump stages. Alternatively, the test gas inlet may be intended to have an axial spacing such that it not only occupies the intermediate space between two turbopump stages, but additionally occupies a portion of one of the two turbopump stages that define the intermediate space, or a portion of each of the two turbopump stages that define the intermediate space.

[0030] Regarding the location of the bypass outlet, it may be intended to be located at the height of one turbopump stage, or downstream of one turbopump stage, particularly between two turbopump stages. Therefore, it is not essential that the bypass outlet be located at the height of the axial intermediate space between two consecutive turbopump stages. The bypass outlet may be located at the height of one of the turbopump stages. Alternatively, the bypass outlet may be intended to have axial dimensions such that it not only occupies the intermediate space between two turbopump stages, but additionally occupies a portion of one of the two turbopump stages that define the intermediate space, or a portion of each of the two turbopump stages that define the intermediate space.

[0031] According to some embodiments, the test gas inlet and bypass outlet may be positioned at at least substantially the same height axially, particularly between two turbopump stages, so that no portion of the turbopump region exists between the axial height of the test gas inlet and the axial height of the bypass outlet. In this case, the test gas reaches the bypass without first flowing through any portion of the turbopump region. The bypass may have, as described elsewhere in this specification, a capillary and / or selection device, particularly a selection diaphragm. In particular, the bypass may be passive if no adjustment device is provided to change the conductance of the bypass to the test gas, which can be achieved, for example, by a capillary or selection device, as described herein.

[0032] Ba Regarding the location of the bypass inlet, that is, if the bypass does not directly lead to the detector, the bypass inlet may be intended to be located at the height of one turbopump stage or between two turbopump stages. The bypass inlet may be intended to have axial dimensions such that it not only occupies the intermediate space between two turbopump stages, but additionally occupies a portion of one of the two turbopump stages that define the intermediate space, or a portion of each of the two turbopump stages that define the intermediate space.

[0033] Generally, the portion of the turbopump region located between the bypass outlet and bypass inlet may be designed to achieve higher compression and / or higher exhaust velocities than the portion of the turbopump region located upstream of the bypass inlet. This can be achieved by a greater number of turbopump stages or by a greater number of interacting rotor and stator vanes that contribute to the pumping action. The portion of the turbopump region located between the bypass outlet and bypass inlet is the portion that is bypassed and therefore does not require the test gas to pass through during control operation. At least a portion of this portion of the turbopump region can be optimized for the highest possible compression and / or the highest possible exhaust velocities, and thus, in vacuum exhaust mode, the detector can be exhausted as quickly as possible in the event of test gas contamination of the detector.

[0034] According to some embodiments, the turbo vacuum pump is connected to the detector exclusively via an axial intake, and the bypass may lead directly to the detector from a bypass outlet located at the height of the turbo pump stage or between two turbo pump stages. Thus, all portions of the turbo pump area located upstream of the bypass outlet are bypassed in this manner.

[0035] In alternative embodiments, the turbovacuum pump is connected to the detector via a plurality of radial intakes spaced apart from each other in the pumping direction, or via one axial intake and one or more radial intakes spaced apart from each other in the pumping direction, in particular, the bypass inlet may be intended to be located at the height of one turbopump stage or between two turbopump stages. In this case, a portion of the turbopump region located upstream of the bypass outlet is bypassed, i.e., the test gas returns to the turbopump region before reaching the detector.

[0036] Alternatively or additionally, even in a turbovacuum pump connected to a detector by essentially one or more radial intakes, it may be intended that the bypass does not return to the turbopump area but leads directly to the detector or to the housing to which the detector is connected, above the turbopump stage furthest upstream. It is also conceivable that two or more bypasses are provided, in which case one or more bypasses each return to the turbopump area and one or more other bypasses lead directly to the detector. In this case, the bypass outlets of the bypasses may, but are not required to be, located at the same axial height, and the bypass outlets may, but are not required to be, located at the same circumferential position with respect to the rotation axis of the vacuum pump rotor.

[0037] Furthermore, the portion of the turbopump region located between the bypass outlet and the radial intake port closest to the bypass outlet on the upstream side may be designed to achieve higher compression and / or higher exhaust velocities than the portions of the turbopump region located further upstream between the radial intake port closest to the bypass outlet on the upstream side and the bypass inlet or the upstream side of the bypass inlet.

[0038] For example, a turbo vacuum pump may have three turbo pump stages upstream of the test gas inlet, in which case, when viewed in the pumping direction, the intake port, the first turbo pump stage, the bypass inlet, the second turbo pump stage, another intake port, the third turbo pump stage, and the test gas inlet are arranged in axial order. For example, the third and second turbo pump stages may be bypassed. At least the third turbo pump stage located immediately upstream of the test gas inlet may be configured to provide higher compression and / or higher pumping speeds than the first and second turbo pump stages.

[0039] This configuration, which will be described later based on one embodiment, is merely one example of a possible design for a vacuum pump unit according to the present invention. The specific configuration can be selected according to the requirements of each case.

[0040] The bypass itself, and any bypass adjustment devices, can, in principle, be designed in a variety of ways. Given that changes in conductance are assumed in each embodiment of the present invention, there are diverse possibilities for changing the conductance of the bypass with respect to each test gas.

[0041] Generally, when a control device is provided, it is possible, but not essential, to reduce the bypass conductance to zero for the vacuum evacuation mode, in which the detector should be evacuated in the event of test gas contamination. Therefore, the conductance can be reduced to zero or greater than zero during the vacuum evacuation mode.

[0042] In some embodiments, the bypass may have at least one gas conduit, and the regulating device may have at least one bypass valve controllable by a control device. The bypass valve may be, for example, a solenoid valve. The flow cross-sectional area of ​​the bypass valve is variable by the control device, for example, continuously variable or stepped. Alternatively, the bypass valve may be a simple switching valve that can be switched between two positions, in particular between a fully open position and a fully closed position.

[0043] For example, a rolling diaphragm may be used as an actuator for a valve configured in a conventional manner. Such a rolling diaphragm may be used as an actuator for a throttle or slider that changes the flow cross-sectional area of ​​a bypass gas pipeline.

[0044] Bypass valves may be located within the gas pipeline, within the turbovacuum pump, particularly adjacent to or within the pump housing, or within a valve unit assigned to the turbovacuum pump. For example, a bypass valve may be located at a bypass outlet directly outside the turbopump area. The valve unit mentioned in connection with one of these embodiments is a group of leak detection device structures generally known to those skilled in the art with respect to their structure and function. The valve unit, also called a valve block, may be connected between the inlet of the object to be vacuumed and the test gas inlet of the turbovacuum pump, and may also be connected to a backup pump to the turbovacuum pump. The valve unit allows for adjustment of the sensitivity of the leak detection device by taking out a different compression of the turbovacuum pump in accordance with the switching of individual valves in the valve unit, in a manner known to those skilled in the art.

[0045] In an alternative configuration, the bypass may have a gas conduit, particularly without valves. The gas conduit may be a capillary tube. Such a gas conduit has higher conductance for lighter gases than for heavier gases. In particular, the bypass may use a gas conduit having higher conductance for helium than for nitrogen or air. According to a possible development of the present invention, a heating device controllable by a control device may be provided for the gas conduit to change the conductance of the gas conduit with respect to the test gas, and the heating output of the heating device is variable to change the conductance of the gas conduit. This allows us to take advantage of the gas-specific temperature dependence of the conductance for the corresponding gas conduit, particularly the capillary tube.

[0046] In a further alternative configuration, the bypass may be intended to have a gas pipeline without valves, which is passable to the test gas but not to heavier external gases, particularly nitrogen, and may be equipped with a selective device, especially a so-called selective diaphragm. For example, if such a selective device is provided at the bypass outlet leading out from the turbopump region, the conductance of the gas pipeline to the test gas will be relatively high. In this case, during the test mode, i.e., during control operation, the test gas can flow through the bypass, but heavier gases cannot.

[0047] The selection device may be located within the gas pipeline, within the turbovacuum pump, particularly adjacent to or within the pump housing, or within a valve unit assigned to the turbovacuum pump.

[0048] In such embodiments of the method according to the present invention, in which a bypass conductance change is made, the bypass conductance is changed to return to a new, relatively high value after the detector has been evacuated, thereby enabling the leak detection device to operate in a new test mode.

[0049] Therefore, in principle, by appropriately adjusting the bypass conductance each time, it is possible to keep the leak detection device running even if temporary contamination of the test gas occurs.

[0050] Contamination of the test gas within the detector can be detected by proper pressure measurement within the detector. If the measured gas pressure within the detector exceeds a predetermined value, the control unit can automatically switch from test mode to vacuum evacuation mode.

[0051] In some embodiments, the conductance of the bypass can be changed by varying the flow cross-sectional area of ​​the bypass valve.

[0052] In further alternative embodiments, the conductance of the bypass can be altered by heating and cooling the gas pipeline for the test gas, particularly the capillary tube.

[0053] According to another aspect of the present invention, as claimed independently herein, the leak detection device has a test gas channel leading directly to a detector. Here, “directly to the detector” is understood to mean that the test gas does not flow in the opposite direction to the pumping direction through any part of the pumping region of the vacuum pump. In particular, there is no backflow of the test gas through the turbopump region. In this case, on the one hand, the vacuum evacuation of the detector by a conventional type of vacuum pump, in particular the turbovacuum pump disclosed herein, and on the other hand, the supply of the test gas to the detector are carried out in somewhat separate channels. For example, the test gas can be led directly to the detector from a valve unit as described herein. By appropriate means, it can be ensured that no external gas, such as nitrogen or air, reaches the detector, or that only a small amount of external gas component permissible for each detector reaches the detector through the test gas channel. Appropriate means may include, for example, capillary and / or selection devices, such as a selection diaphragm as disclosed elsewhere herein. A vacuum pump for evacuating the detector, particularly a turbo vacuum pump as disclosed herein, may in this case be configured without a test gas inlet or may be provided with a closable test gas inlet.

[0054] The present invention will be described illustratively below with reference to the drawings. [Brief explanation of the drawing]

[0055] [Figure 1] A schematic diagram of a leak detection device according to the present invention, to which a test object is connected, is shown according to a first embodiment of the present invention, and the turbo vacuum pump is connected to the detector exclusively via an axial intake port. [Figure 2] An alternative embodiment of the present invention, corresponding to Figure 1, is shown, in which the turbo vacuum pump is connected to the detector via an axial intake and a radial intake. [Modes for carrying out the invention]

[0056] The leak detection devices shown in Figures 1 and 2 each include a vacuum pump unit 11. The vacuum pump unit 11 has a turbomolecular vacuum pump 15, a valve block 14, and a backup pump 39. Of the vacuum pump 15, only the pump housing 16 and the rotating components that perform the pumping action are schematically shown along with the rotor 41. The differences between the two vacuum pumps 15 and the arrangement of the vacuum pumps within the device will be described in detail later.

[0057] The turbo vacuum pump shown in Figure 1 is a split-flow vacuum pump and has an axial intake port 23 for connection to a detector 19. Three turbo pump stages 17a, 17b, and 17c are connected to the axial intake port 23 in the pumping direction P. A Holbeck pump stage 43 is connected to the last turbo pump stage 17c.

[0058] In the embodiment shown in Figure 2, the turbo vacuum pump 15 is also a split-flow pump and has an axial intake port 23 and a radial intake port 23 downstream of it for connection to the detector 19. Between the two intake ports 23 are the first turbo pump stage 18a and the second turbo pump stage 18b. Downstream of the radial intake port 23, the vacuum pump 15 has two further turbo pump stages 18c, 18d, to which the Holbeck pump stage 43 is connected.

[0059] The turbo vacuum pump 15 is connected to a detector 19, which also belongs to a leak detection device in the form of a mass spectrometer. In the embodiment of Figure 1, the detector 19 is connected to an axial intake port 23 via an opening 19a. In the embodiment of Figure 2, the detector 19 is positioned laterally to the vacuum pump 15. The pump housing 16 is here an outer housing, and the pump 15 is inserted into the outer housing together with the base housing, and the detector 19 is connected to the base housing via an opening 19a assigned to the intake port 23. The vacuum pump 15 inserted into the outer housing 16 may be, for example, a so-called cartridge vacuum pump.

[0060] The leak detection devices shown in Figures 1 and 2 each further include a control device 35 that controls the operation of the leak detection device.

[0061] During the control operation (test mode), the test object 13 is connected to the vacuum pump unit 11. As described above, the test object 13 may be a component (test specimen) or a vacuum chamber whose vacuum airtightness should be tested, and the component to be tested is located inside the vacuum chamber.

[0062] For the test mode, the detector 19 and the test object 13 are evacuated to a sufficiently low vacuum pressure by the vacuum pump unit 11. When the test object has a leak, the test gas 21 (usually helium), specifically indicated by arrows in Figures 1 and 2, respectively, reaches the test gas inlet 25 via the valve unit 14, and thus reaches the turbopump region of the turbo vacuum pump 15, which is formed by the individual turbopump stages 17a to 17c (Figure 1) or 18a to 18d (Figure 2).

[0063] As described elsewhere, the valve unit 14 allows for adjustment of the leak detection device's sensitivity. Since the individual valves of the valve unit 14 are connected to ports of the turbo vacuum pump 15 that are spaced apart from each other in the pumping direction P, the compression of the turbo molecular pump 15 is taken up each time, depending on the valve switching state of the valve unit 14, which is selected based on the expected magnitude of the leak in the object 13 to be tested. For example, if a relatively large leak is expected, only the lower of the three valves of the valve unit 14 is opened.

[0064] Each leak detection device operates according to the so-called countercurrent principle, meaning the test gas 21 travels against the pumping direction P to the detector 19, where it is detected. In this case, according to the present invention, the test gas 21 does not need to pass through the entire portion of the turbopump area located upstream of the test gas inlet 25. This is because two bypasses 27a, 27b (Figure 1) or one bypass 28 (Figure 2) are provided, which allow the gas to bypass a portion of the turbopump area located upstream of the test gas inlet 25. The differences between the two embodiments shown in Figures 1 and 2 related to this will be described in detail below.

[0065] In the embodiment shown in Figure 1, two bypasses 27a and 27b are provided for the test gas 21 flowing back through the turbopump region. Alternatively, a single bypass 27 may be provided, or three or more bypasses 27 may be provided.

[0066] The two bypasses 27a and 27b each have a gas pipeline 37 that leads directly to the detector 19 from a bypass outlet 29 that exits the turbopump region. The bypass outlet 29 of bypass 27a, shown on the left in Figure 1, is located between the two turbopump stages 17a and 17b, which are located furthest upstream in the axial direction. The bypass outlet 29 of bypass 27b, shown on the right in Figure 1, is located at the same height as the turbopump region 17a, which is closest to the axial intake port 23 in the axial direction.

[0067] Each of the two gas lines 37 is assigned a control device 33 in the form of a bypass valve 33. The bypass valve 33 may be a solenoid valve that can be controlled by, for example, a control device 35. For example, the control device 35 can switch each valve 33 between an open state and a fully closed state.

[0068] During the control operation for the detector 19 to detect the test gas 21, the valves 33 are open, meaning that the conductance of the gas lines 37 relative to the test gas 21 is relatively high. In this case, the test gas 21 may flow from the test gas inlet 25 in the reverse direction, i.e., opposite to the pumping direction P, through the turbopump region, as specifically indicated by the arrows, to the bypass outlet 29, from where the test gas 21 is guided directly to the detector 19 via the gas lines 37. When the valves 33 are open, the gas lines 37 each have relatively high conductance relative to the test gas 21, so the first turbopump stage 17a, located closest to the intake port 23, is completely bypassed by bypass 27a, shown on the left in Figure 1, and this turbopump stage 17a is partially bypassed by bypass 27b, shown on the right in Figure 1. Overall, this results in a significantly higher test gas flow within the detector 19 compared to when bypasses 27a and 27b are not present, thereby significantly increasing the sensitivity of the detector 19.

[0069] For example, if the pressure of the test gas 21 in the detector 19 is too high due to a relatively large leak in the test object 13, this can be confirmed by measuring the pressure in the corresponding detector 19, in which case the control device 35 will close the bypass valve 33. This means that the conductance of the gas pipeline 37 relative to the test gas 21 decreases, so the turbo vacuum pump 15 can evacuate the detector 19 relatively quickly, and in the process, the discharged test gas 21 cannot return to the detector 19.

[0070] Therefore, the turbo vacuum pump 15 can be designed to enable rapid vacuum evacuation of the detector 19 in the event of test gas contamination or other circumstances, with respect to pumping speed and compression, and this characteristic of the turbo molecular pump 15 does not impair the test gas sensitivity of the detector 19, because during control operation, a portion of the turbo pump area is bypassed based on bypasses 27a and 27b.

[0071] In the embodiment shown in Figure 2, the bypass 28 similarly has a gas conduit 37, and a bypass valve 33, for example in the form of a solenoid valve, is located within the gas conduit 37. The bypass outlet 29 is located axially, at the height of the intermediate space between two turbopump stages 18c and 18d, through which the test gas inlet 25 opens. Since the pressure level at the test gas inlet 25 can be relatively high under certain circumstances, it may be advantageous in control operation to allow at least essentially only the test gas 21 to flow through the bypass 28. In this case, the bypass 28 may have, for example, a capillary and / or selection device, particularly a selection diaphragm, to allow the test gas 21 to pass through but not heavier external gases, as will be discussed elsewhere.

[0072] The test gas 21 can bypass the two first turbopump stages 18c and 18b located upstream of the test gas inlet 25 via the bypass 28, and return axially to the turbopump region via the bypass inlet 31 between the first turbopump stage 18a and the second turbopump stage 18b. From there, the test gas 21 reaches the detector 19, where it is detected. Alternatively, the bypass inlet 31 may be located upstream of the first turbopump stage 18a. Alternatively or additionally, the two first turbopump stages 18a and 18b may be combined to form a single turbopump stage. In this regard, the configuration of the vacuum pump 15 and the positioning of the bypass 28 shown in Figure 2 are merely illustrative.

[0073] The bypass 28 makes it possible to design the turbopump stage 18c, located downstream of the radial intake port 23 of the vacuum pump 15 and just upstream of the test gas inlet 25, to achieve higher compression and higher pumping speeds than the two turbopump stages 18a and 18b located further upstream, by having more rotor and stator vanes. The relatively high compression and relatively high pumping speed of turbopump stage 18c does not impair the test gas sensitivity of the detector 19 because this turbopump stage 18c is bypassed by the bypass 28, but in vacuum evacuation mode, it works to allow the detector 19 to be quickly vacuumed, for example, if the test gas of the detector 19 is contaminated.

[0074] For the vacuum evacuation mode, the valve 33 of the bypass 28 is closed by the control device 35, so that in this operating mode, backflow of the test gas 21 through the gas pipeline 37 of the bypass 28 is prevented.

[0075] In the aforementioned embodiment, the bypass 28 is provided with an adjustment device in the form of a valve 33. As mentioned at the beginning, in another possible embodiment of the present invention, no adjustment device is required for the bypass to change the conductance with respect to the test gas. This application relates to the invention described in the claims, but also includes the following other embodiments. 1. A device for detecting leaks according to the vacuum method using the countercurrent principle, A vacuum pump unit (1) is connected to a test object (13) to be vacuum-evacuated and has a turbo vacuum pump (15) comprising a turbo pump region formed by one or more turbo pump stages (17, 18), A detector (19) for detecting a test gas (21), especially helium, and a mass spectrometer, Equipped with, The turbo vacuum pump (15) is connected to the detector (19) via at least one axial and / or radial intake port (23), and has a test gas inlet (25) downstream of the intake port (23), In an apparatus in which at least a portion of the turbo pump region is located between the intake port (23) and the test gas inlet (25) in the pumping direction (P) of the turbo vacuum pump (15), The apparatus is characterized in that it is provided with at least one bypass (27, 28) for a test gas (21), the bypass (27, 28) leading from a bypass outlet (29) located at the height of the test gas inlet (25) or upstream of the test gas inlet (25) toward the outside of the turbopump area, directly to the detector (19) or to a bypass inlet (31) located upstream of the bypass outlet (29) toward the inside of the turbopump area, while bypassing at least a portion (17a, 18b, 18c) of the turbopump area. 2. The apparatus according to item 1, further comprising an adjustment device (33) for changing the conductance of the bypass (27, 28) with respect to the test gas (21), wherein the adjustment device (33) is controllable by a control device (35) of the apparatus, thereby changing the conductance between a relatively high value and a relatively low value depending on the operating status of the apparatus. 3. The apparatus of the 1 or 2 described above, wherein at least two bypasses (27a, 27b) are provided for the test gas (21), the bypasses (27a, 27b) exiting the turbopump region at different locations and / or leading to the detector (19) or the turbopump region at different locations. 4. The apparatus of the 3, wherein the bypasses (27a, 27b) bypass portions of the turbopump region designed to obtain different heights of compression and / or exhaust velocity, and / or the conductances of the bypasses (27a, 27b) are independently variable. 5. The turbopump region has a plurality of turbopump stages arranged continuously in the pumping direction (P), and the test gas inlet (25) is located downstream of one turbopump stage, particularly between two turbopump stages, and / or The turbopump region has a plurality of turbopump stages arranged continuously in the pumping direction (P), and the bypass outlet (29) is located at the height of one turbopump stage or downstream of one turbopump stage, particularly between two turbopump stages, in any one of the devices 1 to 4 described above. 6. Any one of the devices 1 to 5 described above, wherein the test gas inlet (25) and the bypass outlet (29) are located at at least substantially the same height in the axial direction, particularly between two turbopump stages (18c, 18d), so that the turbopump region does not exist between the axial height of the test gas inlet (25) and the axial height of the bypass outlet (29). 7. The turbopump region has a plurality of turbopump stages arranged continuously in the pumping direction (P), and the bypass inlet (31) is located at the height of one turbopump stage or between two turbopump stages, one of the devices from 1 to 6 above. 8. Any one of the devices 1 to 7, wherein the portion of the turbopump region located between the bypass outlet (29) and the bypass inlet (31) (18b, 18c) is designed to obtain higher compression and / or higher exhaust velocity than the portion of the turbopump region located upstream of the bypass inlet (31) (18a). 9. The turbo vacuum pump is connected to the detector (19) exclusively via an axial intake port (23), and the bypass (27) leads directly to the detector (19) from one bypass outlet (29), in particular the bypass outlet (29) being located at the height of one turbo pump stage (17a) or between two turbo pump stages (17a, 17b), or occupying an intermediate space between two turbo pump stages in the axial direction and a portion of at least one of the turbo pump stages defining the intermediate space, one of the devices from 1 to 8 above. 10. The turbo vacuum pump (15) is connected to the detector (19) via a plurality of radial intake ports (23) spaced apart from each other in the pumping direction (P), or via one axial intake port (23) and one or more radial intake ports (23) spaced apart from each other in the pumping direction (P), and the bypass inlet (31) is located at the height of one turbo pump stage or between two turbo pump stages (18a, 18b), or occupies an intermediate space between two turbo pump stages in the axial direction and a portion of at least one of the turbo pump stages defining the intermediate space, any one of the devices from 1 to 8 above. 11. The apparatus of the 10, wherein the portion (18c) of the turbopump region located between the bypass outlet (29) and the radial intake port (23) closest to the bypass outlet (29) on the upstream side is designed to obtain higher compression and / or higher exhaust velocity than the portions (18a, 18b) located further upstream of the turbopump region, which are located between the radial intake port (23) closest to the bypass outlet (29) on the upstream side and the bypass inlet (31) or the portion (18a, 18b) located on the upstream side of the bypass inlet (31). 12. The bypass (27, 28) has at least one gas conduit (37), the regulating device has at least one bypass valve (33), in particular a solenoid valve, controllable by the control device (35), the flow cross-sectional area of ​​the bypass valve (33) is variable, in particular the flow cross-sectional area can be reduced to a value of 0 for vacuum evacuation mode, any one of the devices from 2 to 11 above. 13. The apparatus of the 12, wherein the bypass valve (33) is located within the gas pipeline (37), within the turbo vacuum pump (15), particularly in contact with or within the pump housing (16), or within a valve unit (14) assigned to the turbo vacuum pump (15). 14. The bypass (27, 28) has a gas conduit (37) without a valve, in particular a capillary, and in particular a regulating device, the regulating device has a heating device for the gas conduit (37) that is controllable by the control device (35), and the heating output of the heating device is variable to change the conductance of the gas conduit (37), any one of the devices from 2 to 13 above. 15. The bypass (27, 28) is provided with a gas pipeline (37) without a valve, which is passable to the test gas but not to an external gas heavier than the test gas, particularly nitrogen, and is equipped with a selective device, particularly a selective diaphragm, one of the devices from 2 to 14 above. 16. The selection device is located within the gas pipeline (37), within the turbo vacuum pump (15), particularly in contact with or within the pump housing (16), or within a valve unit (14) assigned to the turbo vacuum pump (15). 17. A leak detection device, particularly a method for detecting leaks in the vacuum method using any one of the above 1 to 16 leak detection devices, comprising a vacuum pump unit (11) and a detector (19), wherein the vacuum pump unit (11) has a turbo vacuum pump (15) that is connectable to a test object (13) to be vacuum-evacuated and has a turbo pump region, the turbo pump region being formed by one or more turbo pump stages (17, 18), wherein the leak detection device comprises a vacuum pump unit (11) and a detector (19), the vacuum pump unit (11) has a turbo vacuum pump (15) that is connectable to a test object (13) to be vacuum-evacuated and has a turbo pump region, the turbo pump region being formed by one or more turbo pump stages (17, 18), A method comprising providing at least one bypass (27, 28) for a test gas (21), particularly helium, which is generated in the test object (13), enters the turbo vacuum pump (15), and flows toward the detector (19) in the opposite direction to the pumping direction (P), wherein the bypass (27, 28) bypasses at least a portion (17a, 18b, 18c) of the turbo pump area and goes directly to the detector (19) or returns to the turbo pump area. 18. The method of 17, wherein, during the operation of the leak testing device, the conductance of the bypass (27, 28) with respect to the test gas (21) is changed from a relatively high value in the test mode in which the test gas (21) is detected by the detector (19) to a relatively low value in the vacuum exhaust mode in which the detector (19) is evacuated. 19. The method of 17 or 18, wherein after evacuating the detector (19), the conductance of the bypass (27, 28) is changed back to a relatively high value in order to operate the leak detection device again in test mode. 20. One of the methods described in 17 to 19 above, wherein when the gas pressure inside the detector (19) exceeds a predetermined value, the system switches from test mode to vacuum evacuation mode. 21. One of the methods 17 to 20 above, wherein the conductance of the bypass (27, 28) is changed by changing the flow cross-sectional area of ​​the bypass valve (33), and in particular, the bypass valve (33) is completely closed in order to run a vacuum. 22. One of the methods described in 17 to 21 above, wherein the conductance of the bypass (27, 28) is changed by heating and cooling the gas conduit (37) for the test gas (21), particularly the capillary. [Explanation of Symbols]

[0076] 11 Vacuum pump unit 13. Subjects of the Examination 14 valve unit 15 Turbo vacuum pump 16 Pump Housing 17, 18 Turbo pump stages 19 Detectors 19a aperture 21 Test gas 23 Air intake 25 Test gas inlet Bypass 27, 28 29 Bypass Exit 31 Bypass Entrance 33 Adjustment device, bypass valve 35 Control device 37 Gas pipelines 39. Spare pump 41 Rotor 43 Holbeck pump stage P Pumping direction

Claims

1. A device for detecting leaks according to the vacuum method using the countercurrent principle, A vacuum pump unit (11) is connectable to a test object (13) to be vacuum-evacuated and has a turbo vacuum pump (15) comprising a turbo pump region formed by one or more turbo pump stages (17, 18), and a detector (19) for detecting a test gas (21), Equipped with, The turbo vacuum pump (15) is connected to the detector (19) via at least one axial and / or radial intake port (23), and has a test gas inlet (25) downstream of the intake port (23), In an apparatus in which at least a portion of the turbo pump region is located between the intake port (23) and the test gas inlet (25) in the pumping direction (P) of the turbo vacuum pump (15), The apparatus is characterized in that it is provided with at least one bypass (27, 28) for a test gas (21), the bypass (27, 28) leading from a bypass outlet (29) that exits the turbopump area and is located at the height of the test gas inlet (25) or upstream of the test gas inlet (25) to the detector (19) or to a bypass inlet (31) that enters the turbopump area and is located upstream of the bypass outlet (29), while bypassing at least a portion (17a, 18b, 18c) of the turbopump area.

2. The apparatus according to claim 1, further comprising an adjustment device (33) for changing the conductance of the bypasses (27, 28) with respect to the test gas (21), wherein the adjustment device (33) is controllable by a control device (35) of the apparatus, thereby changing the conductance between a relatively high value and a relatively low value depending on the operating status of the apparatus.

3. The apparatus according to claim 1 or 2, wherein at least two bypasses (27a, 27b) are provided for the test gas (21), the bypasses (27a, 27b) exiting the turbopump region at different locations and / or leading to the detector (19) or the turbopump region at different locations.

4. The apparatus according to claim 3, wherein the bypasses (27a, 27b) bypass portions of the turbopump region designed to obtain different heights of compression and / or exhaust velocity, and / or the conductances of the bypasses (27a, 27b) are independently variable.

5. The turbopump region has a plurality of turbopump stages arranged continuously in the pumping direction (P), and the test gas inlet (25) is located downstream of one turbopump stage, and / or The apparatus according to claim 1 or 2, wherein the turbopump region has a plurality of turbopump stages arranged continuously in the pumping direction (P), and the bypass outlet (29) is located at the height of one turbopump stage or downstream of one turbopump stage.

6. The apparatus according to claim 1 or 2, wherein the test gas inlet (25) and the bypass outlet (29) are located at at least substantially the same height in the axial direction, so that the turbopump region does not exist between the axial height of the test gas inlet (25) and the axial height of the bypass outlet (29).

7. The apparatus according to claim 1 or 2, wherein the turbopump region has a plurality of turbopump stages arranged continuously in the pumping direction (P), and the bypass inlet (31) is located at the height of one turbopump stage or between two turbopump stages.

8. The apparatus according to claim 1 or 2, wherein the portion of the turbopump region located between the bypass outlet (29) and the bypass inlet (31) (18b, 18c) is designed to obtain higher compression and / or higher exhaust velocity than the portion of the turbopump region located upstream of the bypass inlet (31) (18a).

9. The apparatus according to claim 1 or 2, wherein the turbo vacuum pump is connected to the detector (19) exclusively via an axial intake port (23), and the bypass (27) leads directly to the detector (19) from one bypass outlet (29).

10. The apparatus according to claim 1 or 2, wherein the turbo vacuum pump (15) is connected to the detector (19) via a plurality of radial intake ports (23) located apart from each other in the pumping direction (P), or via one axial intake port (23) and one or more radial intake ports (23) located apart from each other in the pumping direction (P), and the bypass inlet (31) is located at the height of one turbo pump stage or between two turbo pump stages (18a, 18b), or occupies an intermediate space between two turbo pump stages in the axial direction and a portion of at least one of the turbo pump stages defining the intermediate space.

11. The apparatus according to claim 10, wherein the portion (18c) of the turbopump region located between the bypass outlet (29) and the radial intake port (23) closest to the bypass outlet (29) on the upstream side is designed to obtain higher compression and / or higher exhaust velocity than the portions (18a, 18b) of the turbopump region located further upstream, between the radial intake port (23) closest to the bypass outlet (29) on the upstream side and the bypass inlet (31) or the portion (18a, 18b) located on the upstream side of the bypass inlet (31).

12. The apparatus according to claim 2, wherein the bypass (27, 28) has at least one gas conduit (37), the regulating device has at least one bypass valve (33) controllable by the control device (35), and the flow cross-sectional area of ​​the bypass valve (33) is variable.

13. The apparatus according to claim 12, wherein the bypass valve (33) is located in the gas pipeline (37), in the turbo vacuum pump (15), in contact with the pump housing (16), in the pump housing (16), or in a valve unit (14) assigned to the turbo vacuum pump (15).

14. The apparatus according to claim 2, wherein the bypass (27, 28) has a gas pipeline (37) without a valve.

15. The apparatus according to claim 2, wherein the bypass (27, 28) has a gas conduit (37) and is provided with a selection device that allows passage through the test gas but prevents passage through an external gas heavier than the test gas.

16. The apparatus according to claim 15, wherein the selection device is located in the gas pipeline (37), in the turbo vacuum pump (15), in contact with the pump housing (16), in the pump housing (16), or in a valve unit (14) assigned to the turbo vacuum pump (15).

17. A method for inspecting leaks according to the vacuum method using a leak inspection device, comprising a vacuum pump unit (11) and a detector (19), wherein the vacuum pump unit (11) has a turbo vacuum pump (15) that is connectable to a test object (13) to be vacuum-evacuated and has a turbo pump region, the turbo pump region being formed by one or more turbo pump stages (17, 18), wherein A method comprising providing at least one bypass (27, 28) for the test gas (21) that is generated in the test object (13), enters the turbo vacuum pump (15), and flows toward the detector (19) in the opposite direction to the pumping direction (P), wherein the bypass (27, 28) bypasses at least a portion (17a, 18b, 18c) of the turbo pump area and goes directly to the detector (19) or returns to the turbo pump area.

18. The method according to claim 17, wherein, during operation of the leak testing device, the conductance of the bypass (27, 28) with respect to the test gas (21) is changed from a relatively high value in a test mode in which the test gas (21) is detected by the detector (19) to a relatively low value in a vacuum evacuation mode in which the detector (19) is evacuated.

19. The method according to claim 18, wherein after evacuating the detector (19), the conductance of the bypasses (27, 28) is changed back to a relatively high value in order to operate the leak detection device again in test mode.

20. The method according to claim 18, wherein when the gas pressure inside the detector (19) exceeds a predetermined value, the system switches from test mode to vacuum evacuation mode.

21. The method according to claim 18, wherein the conductance of the bypass (27, 28) is changed by changing the flow cross-sectional area of ​​the bypass valve (33).

22. The method according to claim 18, wherein the conductance of the bypass (27, 28) is changed by heating and cooling the gas conduit (37) for the test gas (21).

23. The apparatus according to claim 1, wherein the test gas (21) is helium.

24. The apparatus according to claim 1, wherein the detector (19) is a mass spectrometer.

25. The test gas inlet (25) is located between two turbopump stages, and / or The apparatus according to claim 5, wherein the bypass outlet (29) is located between two turbopump stages.

26. The apparatus according to claim 6, wherein the test gas inlet (25) and the bypass outlet (29) are located between two turbopump stages (18c, 18d).

27. ​​The apparatus according to claim 9, wherein the bypass outlet (29) is located at the height of one turbopump stage (17a) or between two turbopump stages (17a, 17b), or occupies an intermediate space between two turbopump stages and a portion of at least one of the turbopump stages defining the intermediate space in the axial direction.

28. The apparatus according to claim 12, wherein the bypass valve (33) is a solenoid valve.

29. The apparatus according to claim 12, wherein the flow cross-sectional area can be reduced to a value of 0 for vacuum evacuation mode.

30. The apparatus according to claim 14, wherein the gas conduit (37) is a capillary tube.

31. The apparatus according to claim 14, wherein an adjustment device is provided, the adjustment device having a heating device for the gas pipeline (37) that is controllable by the control device (35), and the heating output of the heating device is variable to change the conductance of the gas pipeline (37).

32. The apparatus according to claim 15, wherein no valve is provided in the gas pipeline (37).

33. The apparatus according to claim 15, wherein the external gas is nitrogen.

34. The apparatus according to claim 15, wherein the selection device is a selection diaphragm.

35. The method according to claim 17, wherein a leak is inspected in accordance with the vacuum method using the leak inspection device according to claim 1 or 2, based on the countercurrent principle.

36. The method according to claim 17, wherein the test gas (21) is helium.

37. The method according to claim 21, wherein the bypass valve (33) is completely closed for vacuum exhaust mode.

38. The method according to claim 22, wherein the gas conduit (37) is a capillary.

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