Method for testing the tightness of a cable and test device therefor

Abstract

A method is specified for testing the tightness of a cable (2) by means of a testing device (4), wherein the cable (2) has at least two end pieces (6), a sheath (8), and a conductor (10), wherein the sheath (8) and the conductor (10) extend between the two end pieces (6), wherein the sheath (8) encloses an interior space (12) in which the conductor (10) is arranged, wherein the cable (2) has a parasitic cavity (14) within the interior space (12), through which a fluidic connection is formed between the end pieces (6), wherein the testing device (4) has a sealing cage (16) for each end piece (6), in which a pressure can be adjusted using a test medium (M), wherein each end piece (6) is inserted into one of the sealing cages (16), such that the parasitic cavity (14) is fluidically connected to the sealing cages (16),wherein a leak test is carried out on at least one of the end pieces (6) using the test medium (M), while a respective pressure is set in all sealing cages (16). Furthermore, a corresponding testing device (4) is specified.

Description

[0001] The invention relates to a method for testing the tightness of a cable and to a testing device which is designed to carry out such a method.

[0002] A cable is used to transmit electrical energy, e.g. from an energy storage device to a consumer, or an electrical signal, e.g. between two devices. The cable can be a simple wire or a more complex wiring harness or something similar. Depending on the intended use, special requirements are placed on the cable with regard to its impermeability to certain media, e.g. air or water. For example, the cable is part of the on-board electrical system of a motor vehicle and is therefore regularly exposed to strong environmental influences such as dirt and moisture. The impermeability of such a cable is then tested during or after production as part of a leak test. If the cable passes the leak test, it is approved for further use; otherwise it is not.

[0003] The cable itself is composed of various elements, such as a sheath, a conductor, and a number of connectors. The primary purpose of the leak test is to check the tightness of the connectors. For this purpose, the connectors are subjected to a test medium at a specific pressure in a test device, and then monitored to determine how the pressure develops over time in order to determine whether there is a leak or something similar. A corresponding test device is described, for example, in patent DE 10 2023 212 790 B3.

[0004] Further reference is made to US 2011 / 0 011 163 A1, CN 1 15 479 735 A, CN 2 16 846 771 U.

[0005] However, the accuracy of the leak test may be limited, for example, when using a stranded conductor as the conductor, since several gaps are formed between the individual strands of the stranded conductor through which the test medium can escape, in addition to escaping via a leak. This additional path can distort the leak test result and, in any case, limits the accuracy achievable in the leak test.

[0006] Against this background, the object of the invention is to improve the leak test on a cable. To this end, an improved method for leak testing and a suitable testing device are to be provided. In particular, the accuracy of the leak test is to be improved.

[0007] The object is achieved according to the invention by a method for leak testing on a cable by means of a testing device, wherein the cable has at least two end pieces, a sheath and a conductor, wherein the sheath and the conductor extend between the two end pieces, wherein the sheath encloses an interior space in which the conductor is arranged, wherein the cable has a parasitic cavity (also referred to as "cavity" for short) within the interior space, through which a fluidic connection is formed between the end pieces, wherein the testing device has a sealing cage for each end piece, in which a pressure can be adjusted using a test medium, in particular air, wherein each end piece is or is inserted into one of the sealing cages, so that the parasitic cavity is fluidically connected to the sealing cages, wherein a leak test is carried out on at least one of the end pieces by means of the test medium,while a respective pressure, in particular a test pressure, is set in all sealing cages. In other words: first, a pressure is set in all end pieces that are fluidically connected via the parasitic cavity, and only when this pressure is set is the actual leak test performed. The pressure that is set is preferably an overpressure, greater than ambient pressure, and / or greater than 1.1 bar. Preferably, the pressure that is set in a respective sealing cage is a test pressure for the end piece in this sealing cage. The aforementioned setting of the pressure before the actual leak test is expediently part of the method according to the invention.

[0008] In this case, it is assumed, without loss of generality, that the pressure in the sealing cage is positive pressure, and then the test medium escapes from the sealing cage. An equivalent configuration, not described in detail below, is one in which the pressure is negative pressure, i.e., lower than the ambient pressure, resulting in a reversed flow direction and the test medium or possibly even ambient air flowing into the sealing cage.

[0009] In this case, it is assumed, without loss of generality, that the cable has exactly two end pieces, but the statements also apply analogously to cables with more than two end pieces.

[0010] The object is further achieved by a testing device which is designed to carry out the method, in particular in combination with a cable as described.

[0011] Advantageous embodiments, further developments, and variants are the subject of the dependent claims. The statements in connection with the leak testing method also apply mutatis mutandis to the testing device, and vice versa. If steps of the method are described implicitly or explicitly below, advantageous embodiments for the testing device result from the fact that it is designed to perform one or more of these steps. In particular, the testing device has a correspondingly designed control unit for this purpose.

[0012] In a suitable design, the same pressure is set in all sealing cages for the leak test. "Equal" is understood in particular to mean "equal within a possible tolerance," which may arise, for example, due to the design or the accuracy of the control of the test device. The pressure differs in particular from the ambient pressure and is either overpressure or underpressure relative to the ambient pressure. Using the same pressure for all end pieces leads to a maximum reduction in the escape of test medium into the cavity (at overpressure; at underpressure, the test medium flows into the cavity analogously) and thus to maximum accuracy.

[0013] Nevertheless, it is also possible to set different pressures for the end pieces, e.g., due to differing requirements and / or specifications. In a suitable design, each end piece then has its own pressure, in particular the test pressure, which is set in the respective sealing cage. This may result in different pressures in the sealing cages and thus a suboptimal compensation, but still a partial compensation, which at least slightly improves accuracy.

[0014] Preferably, the leak test should simultaneously check the tightness of all cable end pieces. Since all end pieces are already subjected to pressure, particularly the respective test pressure, it is possible to test their tightness simultaneously, thus completing the leak test more quickly.

[0015] The test device has a control unit with which the method is implemented. The leak test is centrally controlled by the control unit. For this purpose, all sealing cages are connected to the control unit, e.g., via a bus system of the test device. The sealing cages, in particular the sensors and media supplies, are controlled, for example, using appropriate switches, relays, and / or digital input / output connections.

[0016] In this case, the control unit monitors whether all end pieces are inserted into a respective sealing cage, e.g. by means of a respective presence sensor, and only allows (and also carries out) the leak test when all end pieces are inserted into a respective sealing cage and, in particular, the respective pressure to be set there is also set. Instead of detecting the insertion of an end piece into one of the sealing cages, e.g. by means of a switch contact, and then immediately and automatically carrying out a leak test on the corresponding end piece, the system waits until all end pieces are inserted into a respective sealing cage before then carrying out the leak test. Although the first-mentioned solution has the advantage of starting the leak test as quickly as possible, it prevents the inventive prevention of the test medium escaping from or flowing into the parasitic cavity.

[0017] The sealing cages suitably each have a sensor with which any escape or inflow of the test medium is measured during the leak test. A respective sensor is, for example, a pressure sensor or a flow sensor. The sensor is used to measure, for example, the pressure in the sealing cage as a function of time and then to derive any leakage of the end piece. In particular, each end piece is tested with its own sensor, in contrast to a design in which a central sensor is used to test several end pieces one after the other. The present method is then advantageously parallelized, so that the leak test is carried out on several or all end pieces simultaneously using a respective sensor.

[0018] With the solution described here, locating the leak may be difficult because the end pieces are fluidically connected and may also be tested simultaneously. The leak test on one end piece therefore potentially influences the leak test on another end piece. Therefore, an intelligent evaluation is appropriately carried out in order to identify the end piece with the greatest leak, as this is then very likely to actually be leaking. Using an appropriately designed control unit of the testing device, the results of the leak test of the individual end pieces are jointly evaluated and then a corresponding result is derived and output. This is possible in particular through the above-mentioned use of multiple sensors, namely a separate sensor for each combination of sealing cage and end piece. In a preferred embodiment, a leak is measured for each end piece, e.g.as a pressure drop over a specific time interval, and the end piece with the greatest leakage is identified as leaking. Optionally, the leakage is additionally compared with a predefined limit, and the end piece is only identified as leaking if the leakage also exceeds the limit. The limit can be, for example, an absolute limit or a limit relative to the leakages measured for the other end pieces.

[0019] The sheath is made, in particular, of an electrically insulating material and is then also referred to as insulation. The conductor is made of an electrically conductive material, e.g., copper. Preferably, the conductor is a stranded conductor with multiple wires, and the parasitic cavity corresponds to at least one gusset formed by the wires. Alternatively or additionally, the parasitic cavity is formed between the sheath and the conductor. In particular, the conductor has an outer contour that partially abuts an inner contour of the sheath, thereby forming a corresponding parasitic cavity.

[0020] In a preferred embodiment, at least one of the end pieces is a plug connector, e.g. a plug or socket. Suitably, at least one of the end pieces has a housing and a terminal which is fastened to the end of the conductor and inserted into the housing. In other words: the conductor is in particular pre-assembled with a terminal, i.e. a terminal is fastened to the end of the conductor. The terminal is in particular part of the end piece, so that the conductor is connected to the end piece. The conductor and the sheath run together through a corresponding hole in the housing. The hole is expediently sealed with a seal (e.g. a grommet), through which the sheath and the conductor then run and into the housing.The seal also serves in particular to seal the end piece during the intended use of the cable and the tightness of the seal is therefore expediently, but not necessarily, the subject of the leak test carried out here. However, a design in which the sheath and the housing are manufactured in one piece (monolithic) or are at least materially connected to one another is also suitable. The terminal itself is in particular also attached to the housing, e.g. plugged into it. The terminal forms in particular an electrical connection of the cable for connecting e.g. to a device. Accordingly, the housing in particular has an opening, e.g. a plug-in face, through which the terminal is accessible. During the leak test, this opening points into the sealing cage and is thus sealed against the environment. The test medium also enters the housing through the opening in order to test its tightness.From here, the test medium then, in principle, also enters the parasitic cavity. The above statements apply primarily to all end pieces.

[0021] The terminal, for example, is a crimp that is attached to the end of the conductor and thus secured. In a preferred embodiment, the terminal is an insulation crimp that is also attached to the sheath. The additional attachment to the sheath also provides advantageous strain relief.

[0022] The end pieces suitably each have a seal to seal against the respective sealing cage. The seal also serves, in particular, to seal the end piece during the cable's intended use, and the seal's tightness is therefore appropriately, but not necessarily, the subject of the leak test performed here.

[0023] A key concept of the invention is a synchronized and particularly complex leak test. Instead of testing the various cable end pieces independently of one another, they are simultaneously subjected to a respective pressure in order to reduce or even completely prevent any distortion of the test result caused by the parasitic cavity. This particularly exploits the fact that when pressure is applied simultaneously to all ends of the parasitic cavity, additional leakage via this cavity is no longer possible, or at least only to a limited extent within the framework of possibly differing pressures at the end pieces. In any case, this increases the accuracy of the leak test.

[0024] The invention is based in particular on the observation that the accuracy of a leak test on a cable can be limited due to its design. Problematic, for example, are additionally sealed connectors or cables in the cable if they are intended to pass through a seal, as this can lead to leaks that are difficult to detect. Accordingly, a method is conceivable in which only a presence check of complete seals is carried out, but their leak tightness is not then checked in detail. Equally conceivable is a method in which the leak tightness is also tested in detail, although this is then typically only possible with limited accuracy due to the design of the cable. In the present case, it was observed that, particularly with stranded conductors with crimps attached at the ends (also: crimp contacts), a complete seal along the conductor is not achieved, so that the test medium can escape or flow in here.More precisely, between the individual wires of the conductor on the one hand, and possibly also between the wires and the sheath on the other hand, gussets are formed, for example, which then form one or more parasitic cavities through which the test medium can escape or flow. During the leak test, a corresponding pressure loss occurs, which falsifies the test result. Depending on the size of the cavity, i.e. depending on the specific design of the cable, e.g. with regard to the number and cross-section of the individual wires of the conductor, the leak test can be very inaccurate. When the crimp is applied, sufficient force is typically not applied to completely close the parasitic cavities.

[0025] Therefore, in this case, the start and / or performance of the various measurements for the leak test for the various end pieces are advantageously synchronized as far as possible, i.e. carried out simultaneously if possible, so that the additional leaks into the parasitic cavity cancel each other out as far as possible. This enables a more precise leak test, i.e. in particular a more precise measurement, which then also enables better and more targeted conclusions to be drawn about the quality of the seal actually to be tested, e.g. in the form of cable seals. Nevertheless, a design is also suitable in which a less precise leak test is initially carried out as soon as a single one or only a few end pieces of the cable are connected to the test device and specifically inserted into the sealing cage. In this way, the presence of a seal on the end piece is at least qualitatively detected.The more precise, synchronized, and advantageously quantitative leak test described here follows as soon as all end pieces are connected to the test device. Whether a particular end piece is connected is suitably measured using a presence sensor.

[0026] Generally, a leak test is performed on at least one of the end pieces; this end piece is also referred to as the test end piece. In this case, in addition to the test end piece, all cable end pieces connected to the test end piece via the parasitic cavity are advantageously subjected to a pressure that prevents the test medium from escaping from the test end piece through the parasitic cavity to another end piece (or—in the case of negative pressure—prevents inflow in the opposite direction). It is particularly advisable to test all of these end pieces, which are fluidically connected to one another via the parasitic cavity, simultaneously.However, this is not mandatory; rather, within the scope of the invention it is sufficient that at least a pressure is present there which reduces or completely prevents the test medium from escaping from the test end piece through the parasitic cavity. Furthermore, ideally the same pressure is used for all end pieces in order to achieve maximum accuracy, but this is not absolutely necessary. For example, different test specifications exist for different end pieces, possibly with different test pressures, whereby the additional leakage via the parasitic cavity is still at least reduced. It is particularly important that a pressure is set in each of the end pieces which are fluidically connected via the parasitic cavity in such a way that the pressures counteract each other in order to reduce or completely prevent the test medium from escaping into the cavity.This effect is stronger and the accuracy correspondingly greater the more similar the pressures are.

[0027] The leak test is generally performed on the cable, more specifically on its end pieces. Accordingly, the end pieces are also referred to as "measuring bodies," as the leak test measures their tightness and determines whether or not it is adequate, e.g., by comparing it with a specified limit. The respective result is then output by the test device.

[0028] By design, the parasitic cavity extends along the conductor and the sheath and in the same direction as these. This direction is also referred to as the longitudinal direction. Viewed perpendicular to the longitudinal direction, the cable has a cross-section in which the sheath completely surrounds the conductor and the parasitic cavity. The cavity creates a fluidic connection between the end pieces, i.e. a fluid, in this case specifically the test medium, can flow through the cavity. The cavity is referred to as “parasitic” in this case because it results primarily from the design of the cable and not primarily from the fact that a specific element or medium is to be guided through the cavity. The cavity is in particular hollow, i.e. only filled with air and otherwise empty. The cavity runs in particular continuously, i.e. without interruption, from one end piece to the other.

[0029] Each sealing cage of the test device serves as a holder for a respective end piece. The sealing cages do not necessarily have to be of identical design, and the same applies to the end pieces. Each sealing cage has, in particular, a media supply for the test medium. The test medium flows to the end piece via the media supply, which is then subjected to a corresponding pressure. For this purpose, the end piece is sealed against the sealing cage, and the sealing cage itself is then also sealed. For example, the sealing cage has a recess with a base and a wall that runs around the base. The end piece is inserted into the sealing cage towards the base and sealed against the wall, e.g. by means of a corresponding seal as part of the end piece, e.g. as described above. A volume is now formed between the end piece and the base, into which the test medium flows.For this purpose, the media supply is conveniently integrated into the base or wall. The seal builds up a corresponding pressure. This pressure is typically greater than the ambient pressure, causing the test medium to flow into the environment through any leaks, which is then measured, in particular, by a corresponding sensor in the sealing cage. The sensor is either integrated into the wall or base or formed separately and then connected, for example, via a suitable line, to the specified volume in the sealing cage.

[0030] A particular advantage of the invention is the more precise and faster detection of leaks, i.e., damage to seals on a cable and its end pieces. The method presented here is particularly accurate and also requires very little effort for the operator of the testing device. The method presented here is particularly suitable for leak testing on a cable with a stranded conductor, to which a crimp terminal is attached at the end. The leak tightness of such cables can now be tested with particularly high accuracy. Therefore, replacing the conductor and / or the terminal is not necessary.

[0031] In the following, exemplary embodiments of the invention are explained in more detail with reference to a drawing. In each case, the following schematically show: Fig. 1 a procedure, Fig. 2 a pressure loss due to a parasitic cavity, Fig. 3 a test device and a cable, Fig. 4 a variant of the test device from Fig. 4, Fig. 5 a section of a cable in a perspective view, Fig. 6 the cable Fig. 5 in a side view, Fig. 7 the cable Fig. 5 in a cross-sectional view.

[0032] In Fig. 1 shows an embodiment of a method for testing the tightness of a cable 2 using a testing device 4. Two embodiments of the testing device 4 are shown in the Fig. 3 and Fig. 4, an embodiment of the cable 2 is shown in three different views in the Fig. 5, Fig. 6 and Fig. 7. The cable 2 has at least two end pieces 6 (in Fig. 4 has three end pieces 6), a sheath 8, and a conductor 10, with the sheath 8 and the conductor 10 extending between the two end pieces 6. The sheath 8 encloses an interior space 12 in which the conductor 10 is arranged. The cable 2 has a parasitic cavity 14 (also referred to as "cavity" for short) within the interior space 12, through which a fluidic connection is formed between the end pieces 6.

[0033] As in the Fig. 3 and Fig. 4, the test device 4 has a sealing cage 16 for each end piece 6, in which a pressure can be set using a test medium M, here air. Each end piece 6 is inserted into one of the sealing cages 16 in a first step S1, so that during the leak test each end piece 6 is inserted into a sealing cage 16. In this way, the parasitic cavity 14 is fluidically connected to the sealing cages 16. By means of the test medium M, a leak test is now carried out on at least one of the end pieces 6, while a respective pressure is set in all sealing cages 16. In other words: first, in a second step S2, a pressure is set in all end pieces 6 that are fluidically connected via the parasitic cavity 14, and only when this pressure is set is the actual leak test carried out in a third step S3.The pressure that is set in this case is an overpressure, greater than ambient pressure and / or greater than 1.1 bar. The pressure that is set in a respective sealing cage 16 is in this case a test pressure for the end piece 6 in this sealing cage 16.

[0034] In one possible embodiment, in the second step S2, the same pressure is set in all sealing cages 6 for the leak test. This results in maximum accuracy during the leak test. Alternatively, it is also possible to set different pressures for the end pieces 6, e.g., due to differing requirements and / or specifications. In one possible embodiment, each of the end pieces 6 then has its own pressure, in particular the test pressure, which is set in the respective sealing cage 16. This may then result in different pressures in the sealing cages 16 and thus in a potentially suboptimal compensation.

[0035] In the Fig. 3 and Fig. 4, the leak test in the third step S3 simultaneously checks the leak tightness of all end pieces 6. The test device 4 shown here as an example has a control unit 18 with which the method is implemented. The leak test is centrally controlled by the control unit 18.

[0036] For this purpose, all sealing cages 16 are connected to the control unit 18, e.g. via a bus system of the test device 4.

[0037] In the embodiment shown here, the control unit 18 monitors whether all end pieces 6 are inserted into a respective sealing cage 16, and only allows and carries out the leak test in the third step S3 when all end pieces 6 are inserted into a respective sealing cage 16 and the pressure to be set there is also set.

[0038] The sealing cages 16 each have a sensor 20, e.g., a pressure sensor or flow sensor, which measures any leakage or inflow of the test medium M during the leak test. In the present case, each end piece 6 is tested with its own sensor 20, in contrast to a design in which a central sensor is used to test several end pieces 6 sequentially. The present method is then parallelized, so that the leak test is then performed on each end piece 6 simultaneously with a respective sensor 20.

[0039] In this case, an intelligent evaluation is also carried out to identify the end piece 6 with the greatest leakage, as this is then very likely to actually be leaking. The control unit 18 is designed accordingly and evaluates the results of the leak test of the individual end pieces 6 together and derives a corresponding result from this, which is then output. For each end piece 6, a leak is then measured, e.g. as a pressure drop over a certain time interval, and the end piece 6 with the greatest leakage is identified as leaking. Optionally, the leakage is also compared with a predetermined limit value, and the end piece 6 is only identified as leaking if the leakage also exceeds the limit value.

[0040] The sheath 8 is made of an electrically insulating material. The conductor 10 is made of an electrically conductive material. Fig. 5, Fig. 6 and Fig. 7, the conductor 10 is a stranded conductor with a plurality of wires 22, and the parasitic cavity 14 corresponds to at least one gusset formed by the wires 22. Alternatively or additionally, the parasitic cavity 14 is formed between the sheath 8 and the conductor 10 (not shown).

[0041] In the embodiment shown here, the end pieces 6 are each a connector, e.g., a plug or socket. Each of the end pieces 6 has a housing 24 and a terminal 26, which is attached to the end of the conductor 10 and inserted into the housing 24. Fig. 5, Fig. 6 and Fig. 7, only the terminal 26 is shown and the housing 24 is omitted for clarity. The terminal 26 is part of the end piece 6, so that the conductor 10 is connected to the end piece 6. The conductor 10 and also the sheath 8 run together through a corresponding hole in the housing 24. The hole is sealed, for example, with a seal (not shown), through which the sheath 8 and the conductor 10 then run and into the housing 24. However, an embodiment is also possible in which the sheath 8 and the housing 24 are manufactured in one piece (monolithic) or are at least materially connected to one another. The terminal 26 itself is also fastened to the housing 24, e.g. plugged into it. The terminal 26 forms an electrical connection of the cable 2 for connecting, for example, to a device. Accordingly, the housing 24 has in particular an opening 28, e.g. a plug-in face, through which the terminal 26 is accessible.This opening 28 points into the sealing cage 16 during the leak test and is thus sealed from the environment. The test medium M also enters the housing 24 through the opening 28 to test its leak tightness. From here, the test medium M then, in principle, also enters the parasitic cavity 14. The terminal 26 in this case is a crimp, which is attached to the conductor 10 at the end and thus secured, and specifically even an insulation crimp, which is additionally secured to the sheath 8. The end pieces 6 also each have a seal 30 for sealing against the respective sealing cage 16.

[0042] The method provides a synchronized and complex leak test. Instead of testing the various end pieces 6 of the cable 4 independently of each other, as in Fig. 2, these are simultaneously subjected to a respective pressure in order to reduce or even completely prevent any falsification of the test result by the parasitic cavity 14. This takes advantage of the fact that when pressure is applied simultaneously to all ends of the parasitic cavity 14, additional leakage via this cavity 14 is no longer possible, or at least only to a limited extent within the scope of possibly different pressures at the end pieces 6. In any case, however, the accuracy of the leak test is increased.

[0043] Fig. 2 illustrates the problem that the accuracy of a leak test on a cable 2 can be limited due to its design. In the case of stranded conductors with crimps attached to the ends, a complete seal is not achieved along the conductor 10, so that the test medium M can escape or flow in here. As already described above, between the individual wires 22 of the conductor 10 on the one hand and possibly also between the wires 22 and the sheath 9 on the other hand, gussets are formed, which then form one or more parasitic cavities 14 through which the test medium M can escape or flow in. During the leak test, a corresponding pressure loss results, which in Fig. 2 is illustrated by the arrow 32, which indicates the flow direction of the test medium M (here for the case of overpressure). In contrast, in this case, the start and execution of the various measurements for the leak test for the various end pieces 6 are synchronized as far as possible and carried out simultaneously, so that the additional leaks into the parasitic cavity 14 cancel each other out as much as possible, as indicated by the two arrows 34 in Fig. 3 is indicated.

[0044] Each sealing cage 16 of the test device 4 serves as a receptacle for a respective end piece 6. The sealing cages 16 do not necessarily have to be of identical design; the same applies to the end pieces 6. Each sealing cage 16 has a media supply 36 for the test medium M. The test medium M flows to the end piece 6 via the media supply 36, which is then subjected to a corresponding pressure. For this purpose, the end piece 6 is sealed against the sealing cage 16, and the sealing cage 16 itself is then also sealed. In the examples shown here, the sealing cage 16 has a recess with a base 38 and a wall 40 that runs around the base 38. The end piece 6 is inserted into the sealing cage 6 in the direction of the base 38 and sealed against the wall 40, e.g. by the already mentioned seal 30 as part of the end piece 6. Between the end piece 6 and the base 38, a volume is now formed into which the test medium M flows.The seal builds up a corresponding pressure that is greater than the ambient pressure, so that the test medium M flows through any leaks into the environment, which is then measured with the corresponding sensor 20. In the . Fig. 3 and Fig. 4 the sensor 20 is integrated into the base 38 but can also be integrated into the wall 40 or formed separately and then connected, for example, via a suitable line to the volume in the sealing cage 16. List of reference symbols 2 cables 4 Test device 6 End piece 8 coat 10 ladders 12 Interior 14 (parasitic) cavity 16 Sealing cage 18 Control unit 20 sensors 22 wire 24 housings 26 Terminal 28 Opening (plug-in face) 30 Seal 32 Arrow 34 Arrow 36 Media supply 38 Reason 40 wall M test medium S1 first step (insert end pieces into sealing cages) S2 second step (set pressures) S3 third step (leak test)

Claims

[1] Method for testing the tightness of a cable (2) by means of a testing device (4), a. wherein the cable (2) has at least two end pieces (6), a sheath (8) and a conductor (10), b. wherein the sheath (8) and the conductor (10) extend between the two end pieces (6), c. wherein the sheath (8) encloses an interior space (12) in which the conductor (10) is arranged, d. wherein the cable (2) has a parasitic cavity (14) within the interior (12) through which a fluidic connection is formed between the end pieces (6), e. wherein the test device (4) has a sealing cage (16) for each end piece (6), in which a pressure can be adjusted using a test medium (M), f. wherein each end piece (6) is or is inserted into one of the sealing cages (16) so that the parasitic cavity (14) is fluidically connected to the sealing cages (16), g. wherein a leak test is carried out on at least one of the end pieces (6) by means of the test medium (M), while a respective pressure is set in all sealing cages (16), h. wherein the testing device (4) has a control unit (18) which monitors whether all end pieces (6) are inserted into a respective sealing cage (16) and which only allows the leak test when all end pieces (6) are inserted into a respective sealing cage (16). [2] Method according to claim 1, wherein the same pressure is set in all sealing cages (16) for the leak test. [3] Method according to claim 1, wherein each of the end pieces (6) has its own pressure which is set in the respective sealing cage (16). [4] Method according to one of claims 1 to 3, wherein during the leak test the leak tightness of all end pieces (6) is checked simultaneously. [5] Method according to one of claims 1 to 4, wherein the sealing cages (16) each have a sensor (20) with which an escape or an inflow of the test medium (M) is measured during the leak test. [6] Method according to one of claims 1 to 5, wherein a leakage is measured for each end piece (6) and the end piece (6) which has the greatest leakage is recognized as leaking. [7] Method according to one of claims 1 to 6, wherein the conductor (10) is a stranded conductor with several wires (22), wherein the parasitic cavity (14) corresponds to at least one gusset formed by the wires (22). [8] Method according to one of claims 1 to 7, wherein the parasitic cavity (14) is formed between the sheath (8) and the conductor (10). [9] Method according to one of claims 1 to 8, wherein at least one of the end pieces (6) is a connector. [10] Method according to one of claims 1 to 9, wherein at least one of the end pieces (6) has a housing (24) and a terminal (26) which is attached to the end of the conductor (10) and is inserted into the housing (24). [11] Method according to claim 10, wherein the terminal (26) is an insulation crimp which is additionally also attached to the jacket (8). [12] Method according to one of claims 1 to 11, wherein the end pieces (6) each have a seal (30) for sealing against the respective sealing cage (16). [13] Method according to one of claims 1 to 12, wherein the pressure which is set is an overpressure, is greater than an ambient pressure and / or is greater than 1.1 bar. [14] Testing device (4) which is designed to carry out a method according to one of claims 1 to 13.

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