METHOD FOR TESTING A CABLE SET AND TESTING DEVICE

Description

[0001] The invention relates to a method for testing a cable set using a test device and to such a test device.

[0002] Cable sets are regularly used in the electrical systems of motor vehicles. A cable set connects various components of the vehicle and therefore typically includes one, but usually several, cables. Examples of cables include electrical cables for power and / or data transmission. Such electrical cables have, for example, one or more conductors surrounded by one or more sheaths. Another example of cables are fluid hoses that carry a medium. Regardless of the specific design of the cables, they are typically terminated at their ends with a suitable connector. The cable set itself is thus composed of several individual components, such as a connector housing (part of a connector) and a cable with a sheath enclosed by the connector housing.Therefore, it is desirable that the entire cable assembly be as sealed as possible, especially against water ingress. In other words, the cable assembly should have the highest possible, or at least sufficient, water resistance.

[0003] To test the tightness, and in particular the water resistance, of a cable assembly during manufacturing, a suitably designed test device is used. The cable assembly is connected to the test device, which then performs a leak test, at the end of which it indicates whether the cable assembly is sufficiently tight (pass) or not (fail).

[0004] For example, EP 3 495 796 B1 describes a device and a method for testing a charging socket. The method comprises the steps of: contacting a sealed connector of a wiring network comprising the sealed connector, a charging socket, and a cable connecting the connector and the charging socket, the cable having at least one electrical conductor and insulation enclosing the at least one electrical conductor; supplying a fluid to the sealed connector by means of a test adapter; guiding the supplied fluid from the sealed connector via the cable to the charging socket; and detecting the tightness of the charging socket and the wiring network based on the supplied fluid.

[0005] Reference is made to DE 10 2016 102794 A1 and CN 210 141 974 U.

[0006] Against this background, an object of the invention is to improve the leak test for a cable set. To this end, a suitable test device and a method for testing a cable set using such a test device are to be specified. The test device and the method are to be specifically designed for testing various cable sets.

[0007] The problem is solved according to the invention by a method for testing a cable set using a test device, wherein the test device has at least one test port to which the cable set is or is connected, wherein the test device has a media supply for introducing a test medium into the cable set through the test port, wherein the test device has a flow sensor for a leak test, wherein the flow sensor is arranged in a flow path of the test medium, wherein a test pressure for the cable set is set using the test medium and then a number of measured values ​​are generated with the flow sensor at a flow rate of the test medium, wherein the tightness of the cable set is determined on the basis of the measured values. In the simplest case, the tightness is determined as sufficient (pass) or insufficient (fail). "A number of" generally means "at least one".The introductory statements above apply in particular to the cable set.

[0008] The task is also solved by a testing device which is designed to carry out the procedure.

[0009] Advantageous embodiments, further developments, and variants are the subject of the dependent claims. The statements relating to the method also apply mutatis mutandis to the test device and vice versa. Where steps of the method are described implicitly or explicitly below, advantageous embodiments for the test device result from its configuration to perform one or more of these steps. In particular, the test device includes a correspondingly designed control unit for this purpose.

[0010] This method is used to test a cable assembly using a test device; it is therefore a testing procedure. Within this procedure, the cable assembly is tested for leaks using the test medium. The flow sensor is positioned in the flow path of the test medium and thus measures the amount of test medium flowing into the cable assembly and therefore also through the flow sensor during the leak test. In a first step, the test pressure is set using the test medium, and then, in a second step, the flow rate of the test medium is measured with the flow sensor. The flow sensor is controlled accordingly by a control unit of the test device. The measured values ​​are also received and evaluated by the control unit.

[0011] The test medium is preferably air, regardless of the specific medium the cable assembly will be exposed to during subsequent, intended use. The media supply is accordingly also referred to as the main air supply. The test medium generally flows along the flow path in one direction through the test device and into the cable assembly.

[0012] The leak test includes, in particular, determining the tightness, i.e., generating one or more flow rate measurements and using these to determine the tightness. For the leak test (but not necessarily as part of it), the cable assembly is first connected to the test port in a sealed manner, so that no test medium can escape from the cable assembly during the subsequent leak test. The test port is advantageously separated from the media supply so that no test medium flows towards the cable assembly. The leak test is then preferably carried out using one or more of the following steps: first, in the aforementioned initial step, the test pressure is set, e.g., by first setting a fill pressure, which then subsequently drops to the test pressure.For this purpose, during the first phase, the test port is connected to the media supply, typically via a switching valve, in such a way that the test medium flows into the cable assembly, thereby initially establishing the fill pressure (this is also referred to as the "filling time"). Afterwards, a waiting period is observed to stabilize the pressure within the cable assembly (this is also referred to as the "stabilization time"). Typically, the pressure within the cable assembly drops slightly from the fill pressure during this time, i.e., by 5% to 15%. Alternatively, the test pressure may simply be identical to the fill pressure, and the stabilization period is omitted. In any case, the test pressure will have been established by the end of the first phase. The primary purpose of this first phase is to establish a homogeneous flow of the test medium into the cable assembly. This first phase is typically a few seconds long, e.g., 8 seconds, with 4 seconds each for the fill time and stabilization time.Subsequently, during a second period, the flow rate is measured at least once, preferably repeatedly, and most preferably continuously, using the flow sensor, and the corresponding measured values ​​are output by the flow sensor as a function of time. This second period is therefore also referred to as the "measurement period." The measured values ​​obtained during or at the end of the measurement period are then used to determine the tightness. The measurement period typically lasts longer than the first period, for example, an order of magnitude longer, lasting from 10 to 100 seconds.

[0013] The tightness is also appropriately evaluated, generating a rating that is output by the test device. For example, the tightness is assessed by comparison with a limit value. Depending on the result of the comparison, a rating is then generated, indicating, for example, whether the cable set has passed the tightness test, i.e., exhibits sufficient tightness (pass), or not, i.e., exhibits insufficient tightness (fail). The rating is then displayed via an output element (e.g., light, speaker, screen, etc.) of the test device.

[0014] During the leak test, the tightness is ultimately determined based on the flow rate, effectively performing a leakage measurement. This is based on the premise that if the cable assembly is not properly sealed, the test medium will continuously escape, allowing for a constant inflow of test medium, which occurs at a suitably set test pressure. This results in a non-zero flow rate (also referred to as the "leakage rate"), meaning it is greater than 0 ml / min. In contrast, with a perfectly sealed cable assembly, no test medium would escape, and a flow rate of 0 ml / min would be reached after the cable assembly is completely filled. The flow rate reached after a specific time (especially after the measurement period) is therefore a measure of the tightness. In principle, even a single measurement is sufficient, e.g.,at the end of the measurement period.

[0015] It is advisable to choose a non-zero value as the limit for assessing the tightness, e.g., 1.8 ml / min. If the flow rate falls below the limit within the measurement period, then the cable set is sufficiently tight (pass); otherwise, it is not (fail).

[0016] In a suitable configuration, the flow sensor uses a measurement method based on thermal heat transfer. A controlled temperature sensor is exposed to the flow of the test medium, which cools it to a greater or lesser degree depending on the flow rate. This effect generates a measurement value which, with appropriate calibration, indicates the actual flow rate.

[0017] The leak test is preferably carried out with a test pressure of a maximum of 1 bar (low pressure), preferably in the range of 100 mbar to 500 mbar, e.g. 200 mbar.

[0018] Leak testing using a flow sensor, as described, is particularly simple because no complicated calculations are required to determine and evaluate the leak tightness. Furthermore, the overall testing time is very short. In addition, a particularly high level of measurement accuracy is achieved, allowing even minor leaks to be detected, especially those caused by only localized damage to the cable harness.

[0019] In principle, it is conceivable to use a general test fixture, such as one designed for a laboratory environment, for leak testing. However, such test fixtures are typically expensive, not very robust, require regular maintenance, have a wider measuring range than is necessary for testing cable assemblies, and lack some features desirable for cable assembly testing. At the same time, the environmental conditions during cable assembly manufacturing are considerably harsher compared to a laboratory application.

[0020] Preferably, the flow sensor has a maximum measuring range of 2 ml / min to 100 ml / min, more preferably 2.5 ml / min to 25 ml / min. It has been found that in 90% of cases, a leak test is sufficient only within the range of 2.5 ml / min to 25 ml / min. By limiting the range accordingly, it is then possible to use a particularly cost-effective and, in particular, only a single flow sensor.

[0021] The test device expediently includes a switching valve for controlling the supply of the test medium. The switching valve is opened to start the leak test. After completion of the leak test, the switching valve is closed again. During the first period for setting the test pressure, the switching valve is open. It is also open during the second period for measuring the flow rate, allowing a continuous flow of test medium. During the measurement period, an equilibrium is established in which the inflow of test medium into the cable harness exactly matches the outflow of test medium through any leaks in the cable harness. The switching valve is controlled accordingly by the test device's control unit, i.e., opened and closed.

[0022] The flow sensor is suitably arranged along the flow path between the switching valve and the at least one test port. In other words, the flow sensor is arranged downstream of the switching valve and upstream of the test port.

[0023] It was found that setting the test pressure during the initial test period is particularly advantageous for additionally checking the cable set for any blockages (e.g., kinks or pressure points). This is based on the observation that the cable set must first be filled with the test medium during this initial period, resulting in a correspondingly high flow rate at the flow sensor, e.g., up to 100 ml / min at a test pressure of 200 mbar. Since the cable set is generally elongated and may also contain cavities that are not directly connected to the test port but are located far from it, the test medium must first travel a certain distance through the cable set to completely fill it. If a blockage exists along this path, e.g.,Because the cable assembly is not correctly mounted in the test fixture and is locally compressed, kinked, or pinched, this blockage prevents the further flow of the test medium, thus reducing the test volume (i.e., the volume that can be filled with the test medium) in the hose. Accordingly, in this case, before or at the beginning of the measurement period (the second period), the cable assembly is filled with the test medium during an initial time interval, and a decrease in the flow rate is determined. In other words, before or at the beginning of the measurement period, an initial flow of the test medium into the cable assembly is monitored and quantified and, for example, compared with a limit value. Generally, a sharp increase is expected at the beginning, followed by a decrease in the flow rate. If a blockage is present, the flow rate decreases significantly faster than without a blockage; the decrease is therefore considerably greater.The initial time interval is preferably a portion of the previously mentioned measurement time. The flow rate is measured during this initial interval, but not for the actual leak test; rather, it's for a preceding blockage test. The decrease in the flow rate is then used to determine whether the cable assembly has a blockage that prevents complete filling with the test medium (blockage test function). For this purpose, the decrease (e.g., as a negative slope, i.e., a change over a specific time interval) of the flow rate is measured as a function of time. This decrease is then compared to a limit value, and depending on whether the decrease is greater or less than this limit value, a blockage is concluded (greater than limit value) or not (less than limit value), and the test device issues a corresponding notification.

[0024] In a suitable variant, either alternatively or additionally, the cable harness is filled with the test medium during an initial time interval at the beginning of the leak test, and the increase in the flow rate is measured. In other words, at the start of the leak test, the initial flow of the test medium into the cable harness is monitored and quantified and, for example, compared with a limit value. Generally, a strong increase is expected at the beginning; otherwise, a blockage is likely present. The initial time interval is preferably part of the aforementioned initial period for setting the test pressure and, in a suitable configuration, corresponds to the filling time until the filling pressure is reached. In particular, the initial time interval begins with the opening of the switching valve, i.e., generally with the start of the leak test, and then ends, for example, when the filling pressure is reached; any stabilization is therefore not taken into account.The flow rate is measured during the initial time interval, but not for the actual leak test; rather, it's for a preceding blockage test. The increase in the flow rate is then used to determine whether the cable assembly has a blockage that prevents it from being completely filled with the test medium (blockage test function). For this purpose, the slope of the flow rate is measured as a function of time, or the time at which a maximum is reached is determined. The slope, the time, or the maximum reached is then compared to a limit value, and depending on whether this limit is higher or lower, a blockage is concluded or not, and the test device issues a corresponding notification.

[0025] To enable testing of as many different cable sets as possible with the same test device, the device suitably has several test ports to which the cable set is connected, depending on its configuration. Only those test ports to which the cable set is actually connected are activated and used during the leak test. In an advantageous embodiment, the test device has several selection valves and several test ports that can be activated by means of the selection valves to direct the test medium to the respective test port. The cable set is then only connected to a subset of the test ports, and the selection valves activate only those test ports to which the cable set is connected before the start of the leak test.The test medium is then supplied only to the activated test ports; the remaining test ports remain disconnected from the media supply. Conveniently, the test device automatically detects whether a cable set is connected to a particular test port, for example, by means of a presence sensor that sends a corresponding presence signal to the control unit when a cable set is connected to the associated test port. Alternatively, the selection valves can be switched manually, or the control unit can be configured to specify which cable set is to be tested and then retrieve from a database which test ports should be activated for this purpose. The test device thus allows for a selection of the test ports to be used (selection function) and is therefore particularly flexible for testing different cable sets.Different cable sets can then be tested at the same workstation using the same testing device.

[0026] Ideally, at least two of the test ports can be activated using the same selection valve, meaning a single selection valve can activate multiple test ports. While this slightly reduces flexibility, it also limits the number of selection valves required, making the test device more cost-effective and simplifying the control system. For example, the test device might have one or more (e.g., four) selection valves, each connected to two test ports, so that two test ports can always be activated with a single selection valve. This is particularly advantageous when both ends of a cable are connected to the test device. Since a cable typically has two ends, only an even number of test ports are needed.

[0027] Before the actual leak test, it is advantageous to check the test device itself for correct functionality and, in particular, to ensure that cable sets with defective sealing are reliably detected. Therefore, in an advantageous embodiment, the cable set is a reference cable set exhibiting defective sealing, and the test device is only released for testing further cable sets once the defective sealing of the reference cable set has been successfully detected during the leak test. This is also referred to as the "release test for the release of the test device." Thus, before the leak test on an actual cable set, a reference test is performed on a reference cable set (release test function). The reference cable set is also referred to as the "bad sample" or "golden sample."The reference cable set is intentionally designed with a defective seal, such that the test device detects this defect (i.e., outputs a "fail" message) when functioning correctly. The release test is always performed, for example, at shift changes when the test device is handed over from one worker to the next.

[0028] Advantageously, the test device includes a proportional valve for setting the test pressure. This proportional valve is located in the flow path, specifically between the media supply and the switching valve. The proportional valve reduces the pressure supplied by the media to the required pressure for the leak test. The proportional valve is controlled accordingly, particularly by the control unit. A precision regulator for setting the test pressure is not required, nor is one present. Optionally, a manual valve (e.g., with a pressure gauge) is also located in the flow path between the media supply and the proportional valve. This valve allows for a rough initial reduction of the pressure from the media supply, which is then automatically fine-tuned by the proportional valve.For example, the media supply provides a pressure of 6 bar, which is pre-reduced to approximately 1 bar using the manual valve, and then reduced particularly precisely to a test pressure below 1 bar using the proportional valve.

[0029] One of the primary functions of a proportional valve is to generate a stable test pressure. In a suitable configuration, the proportional valve is a continuous valve which, for example, with a proportional solenoid, allows not only discrete switching positions but also a continuous transition of the opening degree from open to closed and / or vice versa. The proportional valve is particularly suitable for applications requiring a variable flow rate, such as the test procedure described here. The proportional valve exhibits a non-linear flow rate characteristic.

[0030] Preferably, the test device includes a pressure vessel along the flow path to stabilize the test medium and / or reduce turbulence. The pressure vessel is advantageously arranged upstream of the switching valve and downstream of the proportional valve. The pressure vessel suitably has a volume in the range of 50 ml to 500 ml, e.g., 100 ml.

[0031] The test device preferably includes a locking mechanism that secures the cable assembly to the test terminal during the leak test. This locking mechanism is preferably connected to the media supply and actuated by the test medium. Advantageously, the locking mechanism is part of a safety mechanism of the test device, designed to prevent, or at least allow, the cable assembly to be removed from the test terminal during the test, e.g., by being pulled off.

[0032] In a suitable embodiment, the test device for each test port includes a presence sensor that outputs a presence signal if the cable set is connected to that port. Regardless of whether a safety mechanism is present, the locking mechanism secures the cable set to the respective test port, i.e., prevents it from being removed. For this purpose, the locking mechanism includes a locking element for each test port. In a suitable embodiment, the locking element is a hook cylinder. "Locking" does not mean opening or closing the test port to allow the test medium to flow into or out of the cable set; this is appropriately achieved, if necessary, by means of a suitable switching valve.It is particularly advantageous to use the control unit to measure whether and which presence signals are present and to actuate the locking mechanism accordingly, so that the cable set is locked during the leak test. The presence signals are received and evaluated by the control unit, which then controls the locking mechanism accordingly. The presence signal is, for example, a simple electrical voltage output by the corresponding presence sensor.

[0033] In a suitable embodiment, the locking mechanism has a locking element (as mentioned above) and a closing valve for each test port; that is, a separate closing valve for each locking element. To lock the cable set, the respective closing valve is opened, thereby actuating the corresponding locking element by means of the test medium. Therefore, air, in particular compressed air, is preferably used to lock the cable set; alternatively, the locking element is electrically actuated. Unlocking is performed in the reverse manner.

[0034] Exemplary embodiments of the invention are explained in more detail below with reference to a drawing. Each drawing schematically shows: Fig. 1 a method for testing a cable set, Fig. 2 a test device for the procedure from Fig. 1 , Fig. 3 the flow rate as a function of time.

[0035] In Fig. 1 Figure 1 shows an embodiment of a method for testing a cable set 2 using a test device 4. Figure 2 shows an embodiment of the test device 4. Figure 3 shows an embodiment of the test device 4. Fig. 2 The test device 4 has at least one test port 6 to which the cable set 2 is or will be connected. The cable set 2, shown here as an example, has two conductors, each with two ends, each with a connector (not explicitly labeled), and is connected to four of the eight test ports 6. The test device 4 also has a media supply 8 to introduce a test medium, in this case air, into the cable set 2 through the test port 6. Furthermore, the test device 4 has a flow sensor 10 for leak testing. The flow sensor 10 is arranged in a flow path S of the test medium. In a first step S1, a test pressure pt is set for the cable set 2 using the test medium, and then in a second step S2, a number of measured values ​​12 are generated with the flow sensor 10 at a flow rate Q of the test medium.In a third step, S3 uses the measured values ​​12 to determine the tightness D of the cable set 2. The flow sensor 10 is controlled by a control unit 14 of the test device 4. The measured values ​​12 are also received and evaluated by the control unit 14.

[0036] The leak test includes determining the tightness D, i.e., generating one or more measured values ​​12 for the flow rate Q, and using these values ​​to determine the tightness D. For the leak test (but not necessarily as part of it), the cable set 2 is first connected to the test port 6. The test port 6 is disconnected from the media supply 8, so that no test medium yet flows towards the cable set 2. The leak test is then carried out by means of the following steps: first, in the first step S1, the test pressure pt is set. An embodiment of this is described with reference to Fig. 3 The flow rate Q as a function of time t is explained below: In an initial period t1, a filling pressure pf is first established, which then subsequently drops to the test pressure pt. For this purpose, during the first period t1, the test port 6 is connected to the media supply 8 by means of a switching valve 16 such that the test medium flows into the cable assembly 2, thereby initially establishing the filling pressure pf (this is also referred to as the "filling time"). Afterwards, a waiting period is observed to stabilize the pressure within the cable assembly 2 (this is also referred to as the "stabilization time"). Typically, the pressure within the cable assembly 2 drops slightly from the filling pressure pf during this time. Alternatively, the test pressure pt is simply identical to the filling pressure pf, and the stabilization period is omitted (not shown). At the end of the first period t1, the test pressure pt has been established.The first period t1 primarily serves to establish a homogeneous flow of the test medium into the cable assembly 2. This first period t1 lasts a few seconds, for example, 8 s, with 4 s each for filling and stabilization. Subsequently, in the second step S2, during a second period t2, the flow rate Q is measured once or repeatedly, e.g., continuously, using the flow sensor 10. The flow sensor 10 outputs corresponding measured values ​​12 as a function of time t. The second period t2 is therefore also referred to as the "measurement time." The measured values ​​12 obtained during or at the end of the measurement time are then used in the third step S3 to determine the tightness D. The measurement time typically lasts longer than the first period t1, e.g., 40 s.

[0037] In the third step S3, the tightness D is also evaluated, generating a rating which is output by the test device 4 (not shown). For example, the tightness D is evaluated by comparison with a limit value g, e.g., as in Fig. 3 recognizable. Depending on the result of the comparison, an evaluation is then generated, which, for example, simply indicates whether cable set 2 has passed the leak test, i.e., exhibits sufficient leak tightness D (pass, in). Fig. 3 the solid line), or not, i.e., it exhibits a defective tightness D (fail, in Fig. 3 the dotted line).

[0038] During the leak test, the tightness D is ultimately determined based on the flow rate Q, thus effectively performing a leakage measurement. This is based on the assumption that if the tightness D of cable set 2 is insufficient, the test medium will continuously escape from the cable set 2, allowing for a continuous inflow of test medium, which occurs at a correspondingly set test pressure pt. This results in a non-zero flow rate Q (also referred to as the "leak rate"), i.e., it is greater than 0 ml / min, as shown in Fig. 3 This is shown as an example. In contrast, with a perfectly sealed cable set 2, no test medium would escape, and after the cable set 2 is completely filled, a flow rate Q of 0 ml / min would be established. The flow rate Q reached after the measurement time t2 is therefore a measure of the tightness D. In principle, a single measured value 12 is therefore sufficient, e.g., at the end of the measurement time t2.

[0039] The limit value g for evaluating the tightness D is chosen here as a value other than zero, e.g. 1.8 ml / min. If the flow rate Q falls below the limit value g within the measurement time t2, then the cable set 2 is sufficiently tight (pass), otherwise not (fail).

[0040] The test device 4 shown here has a switching valve 16 for controlling the supply of the test medium M. The switching valve 16 is opened to start the leak test. After completion of the leak test, the switching valve 16 is closed again. During the first period t1, for setting the test pressure pt, the switching valve 16 is open. The switching valve 16 is also open during the second period t2, for measuring the flow rate Q, so that test medium can continuously flow in. During the measurement time t2, an equilibrium is established in which the inflow of test medium into the cable assembly 2 exactly corresponds to the outflow of test medium through any leaks in the cable assembly 2. The switching valve 16 is controlled accordingly by the control unit 14 of the test device 4, i.e., opened and closed.

[0041] In the illustrated embodiment, the flow sensor 10 is arranged along the flow path S between the switching valve 16 and the test port 6.

[0042] During the first period t1, the cable set 2 must first be filled with the test medium, resulting in a correspondingly high flow rate Q at the flow sensor 10, e.g. up to 100 ml / min at a test pressure of 200 mbar, as shown in Fig. 3 This is evident. Since the cable set 2 is generally elongated and may also contain cavities that are not directly connected to the test port 6, but are located far from it, the test medium must first travel a certain distance through the cable set 2 to completely fill it. If there is a blockage along this path, for example, because the cable set 2 is not correctly mounted in the test device 4 and is locally compressed, kinked, or pinched, then the further flow of the test medium is prevented by this blockage, which is correspondingly evident when measuring the flow rate Q. Accordingly, a decrease 18 in the flow rate Q is determined before or at the beginning of the measurement time t2 during an initial time interval ti. Generally, a sharp increase is observed at the beginning, as in Fig. 3 The expected outcome was shown, but then a decrease in the flow rate Q, as also shown in Fig. 3 This is noticeable. If a blockage is present, the flow rate Q drops significantly faster, and the reduction 18 is greater. The initial time interval ti is, in this case, a part of the previously mentioned measurement time t2. The flow rate Q is already measured during the initial time interval ti, but not for the actual leak test; rather, for a preceding blockage test. Based on the reduction 18 of the flow rate Q, it is then determined whether the cable set 2 has a blockage that prevents complete filling with the test medium (blockage test function). For this purpose, the reduction 18 is measured, for example, as the change in the flow rate Q within the initial time interval ti.The reduction 18 is then compared with a limit value and depending on whether the reduction 18 is greater or less than this limit value, a conclusion is drawn about a blockage (greater than limit value) or not (less than limit value) and a corresponding indication is issued by the test device 4.

[0043] To enable testing of as many different cable sets 2 as possible with the same test device 4, the device shown here has several test ports 6. Depending on its configuration, the cable set 2 is connected to these ports, and only those test ports 6 to which the cable set 2 is actually connected are activated and used during the leak test. The test device 4 even has several selection valves 20 and several test ports 6, which can be activated by means of the selection valves 20 to direct the test medium to the respective test port 6. The cable set 2 is then only connected to a subset of the test ports 6, and the selection valves 20 activate only those test ports 6 to which the cable set 2 is connected before the start of the leak test.The test medium is then supplied only to the activated test ports 6; the remaining test ports 6 remain disconnected from the media supply 8. For example, the test device 4 automatically detects whether a cable set 2 is connected to a particular test port 6, e.g., by means of a presence sensor (not shown), which outputs a corresponding presence signal to the control unit 14 when a cable set 2 is connected to the associated test port 6. Alternatively, the selection valves 20 are switched manually, or the control unit 14 is configured to specify which cable set 2 is to be tested and then retrieves from a database which test ports 6 should be activated for this purpose. The test device 4 thus enables a selection of the test ports 6 to be used (selection function) and can therefore be used to test different cable sets 2.

[0044] In the illustrated embodiment, at least two of the test ports 6 can be enabled by means of the same selection valve 20, i.e., a single selection valve 20 enables several test ports 6. For example, the test device 4 has, as in Fig. 2 The figure shows four selection valves 20, each connected to two test terminals 6, so that two test terminals 6 can always be activated by a single selection valve 20. Since each line of the cable set 2 typically has two ends, only an even number of test terminals 6 is required.

[0045] Before the actual leak test, it is advantageous to check the test device 4 itself for correct functionality and to ensure that cable sets 2 with defective sealing D are reliably detected. Therefore, in one embodiment, the cable set 2 is a reference cable set which exhibits defective sealing D, and the test device 4 is only released for testing further cable sets 2 once the defective sealing D of the reference cable set has been successfully detected during the leak test. The reference cable set intentionally has defective sealing D, which is designed in such a way that the test device 4 recognizes it as such when functioning correctly (i.e., outputs "fail").

[0046] The test device 4 shown here also includes a proportional valve 22, which is used to set the test pressure pt. The proportional valve 22 is located in the flow path S between the media supply 8 and the switching valve 16. The proportional valve 22 reduces the pressure supplied by the media supply 8 to the pressure required for the leak test, as needed. The proportional valve 22 is controlled accordingly by the control unit 14. Optionally, a manual valve 24 is also located in the flow path S between the media supply 8 and the proportional valve 22. This valve is used to initially reduce the pressure from the media supply 8 coarsely, before the proportional valve 22 automatically fine-tunes it.

[0047] Optionally, the test device 4 includes a pressure vessel 26 along the flow path S for stabilizing the test medium and / or reducing turbulence. The pressure vessel 26 is located upstream of the switching valve 16 and downstream of the proportional valve 22.

[0048] The test device 4 also optionally includes a locking mechanism 28, which locks the cable set 2 at the test port 6 during the leak test. The locking mechanism is connected to the media supply 8 and is actuated by the test medium. The locking mechanism 28 locks the cable set 2 at the respective test port 6. For this purpose, the locking mechanism 28 has a locking element 30 for each test port 6, e.g., a hook cylinder. The locking mechanism 28 shown here also has a closing valve 32 for each test port 6. To lock the cable set 2, a respective closing valve 32 is opened, thereby actuating the respective locking element 30 by means of the test medium (in Fig. 2 (The connections between the closing valves 32 and the locking elements 30 for the supply of the test medium are omitted for clarity). Alternatively, the locking element is electrically actuated (not shown). Unlocking is performed in reverse.

[0049] In the exemplary embodiment of the Fig. 2 The test device 4 also has a distributor 34 downstream of the media supply 8, with which the test medium is distributed to the various closing valves 32 and in the direction of the test connections 6. Reference symbol list

[0050] 2 Cable set 4 Test device 6 Test connection 8 Media supply 10 Flow sensor 12 Measured value 14 Control unit 16 Switching valve 18 Lowering 20 Selection valve 22 Proportional valve 24 Manual valve 26 Pressure bottle 28 Locking mechanism 30 Locking element 32 Closing valve 34 Distributor DD Leakage g Limit value pf Filling pressure pt Test pressure Q Flow rate S Flow path S1 First step S2 Second step S3 Third step t Time t1 First period t2 Second period, Measurement time t Initial time interval

Claims

1. Method for testing a cable set (2) using a test device (4), a. wherein the test device (4) has at least one test terminal (6) to which the cable set (2) is or will be connected, b. wherein the test device (4) has a medium supply (8) to convey a test medium into the cable set (2) through the test connection (6), c. wherein the test device (4) has a flow sensor (10) for a leak testing, wherein the flow sensor (10) is disposed in a flow path (S) of the test medium, d. wherein a test pressure (pt) for the cable set (2) is set using the test medium and then a number of measurement values (12) relating to a flow rate (Q) of the test medium are generated with the flow sensor (10), e. wherein a tightness (D) of the cable set (2) is determined, based on the measurement values (12), characterized in that f. the flow rate (Q) is measured with the flow sensor (10) during a time period (t2), g. before or at the beginning of the time period (t2) during an initial time interval (ti), a reduction (18) of the flow rate (Q) is determined, h. based on the reduction (18) is determined whether the cable set (4) has a blockage that prevents it from being completely filled with the test medium.

2. The method according to claim 1, wherein the flow sensor (10) has a measuring range of 2 ml / min to 100 ml / min, preferably from 2.5 ml / min to 25 ml / min.

3. The method according to claim 1 or 2, wherein the test device (4) has a switching valve (16) which is opened to start the leak test, wherein the flow sensor (10) is arranged along the flow path (S) between the switching valve (16) and the at least one test connection (6).

4. The method according to any one of claims 1 to 3, wherein the test device (4) has several selection valves (20) and several test connections (6) which can be activated by means of the selection valves (20) in order to convey the test medium to the respective test connection (6), wherein the cable set (2) is only connected to a subset of the test connections (6), wherein, by means of the selection valves (20), only those test connections (6) to which the cable set (2) is connected, are activated before the start of the leak test.

5. The method according to claim 4, wherein at least two of the test connections (6) can be enabled by means of the same selection valve (20).

6. The method according to any one of claims 1 to 5, wherein the cable set (2) is a reference cable set which has a defective tightness (D), wherein the test device (4) is only released for testing further cable sets (2) when, during the leak tightness test of the reference cable set, its defective tightness (D) was successfully detected.

7. The method according to any one of claims 1 to 6, wherein the test device (4) has a proportional valve (22) with which the test pressure (pt) is set.

8. The method according to any one of claims 1 to 7, wherein the test device (4) has a pressure vessel (26) along the flow path (S).

9. The method according to any one of claims 1 to 8, wherein the test device (4) has a locking mechanism (28) with which the cable set (2) is locked at the test connection (6) during the leak test, wherein the locking mechanism (28) is connected to the media supply (8) and is actuated by means of the test medium.

10. Test device (4), a. which has at least one test connection (6) to which a cable set (2) is or will be connected, b. which has a media supply (8) to convey a test medium into the cable set (2) through the test connection (6), c. which has a flow sensor (10) for leak testing, wherein the flow sensor (10) is disposed in a flow path (S) of the test medium, d. which is configured such that i. a test pressure (pt) for the cable set (2) is set using the test medium and then a number of measurement values (12) relating to a flow rate (Q) of the test medium are generated with the flow sensor (10), ii. the tightness (D) of the cable set (2) is determined, based on the measurement values (12), iii. the flow rate (Q) is measured by the flow sensor (10) during a period of time (t2), iv. before or at the beginning of the time period (t2) during an initial time interval (ti), a reduction (18) of the flow rate (Q) is determined, v. based on the reduction (18) is determined whether the cable set (4) has a blockage that prevents it from being completely filled with the test medium.