A wiring harness insulation testing device

Abstract

Invention relates to a wiring harness insulation testing device, comprising a first testing chamber for receiving one end of tested wiring harness with an electrical connector and a second testing chamber for receiving another end of tested wiring harness with an electrical connector. Each testing chamber comprising a chamber bottom and chamber top, which are openable in a released state and lockable into a hermetically closed state around said electrical connectors and around the insulation at the ends of said wiring harness to be tested. Each testing chamber comprising electrical testing means, an inlet connected to the means for generating negative or positive gas pressure inside said testing chamber, means for measuring pressure in said testing chamber, a control unit, which is configured to perform high-voltage tests on said wiring harness with said electrical testing means.

Description

A wiring harness insulation testing deviceTECHNICAL FIELD

[0001] Present invention relates to a wiring harness insulation testing device mainly for an automotive industry but is not limited thereto. Said testing device is suitable also for use in the industries for production of other transportation means, such as rail transportation means (such as electric trains, trams), agricultural vehicles (such as tractors, efc.) shipbuilding (ships, boats, other floating vessels), aircrafts, heavy transportation means (such as heavy equipment vehicles, heavy machinery, earthmovers, construction vehicles, etc).

[0002] Specifically, the invention relates to the insulation testing device of the non-shielded high-voltage wiring harnesses. Generally, in the context of the invention, a wiring harness, also known as a wire harness, cable assembly, cable harness, wiring assembly or wiring loom, is an assembly of electrical cables or wires which transmit signals or electrical power in a means of transport, such as an automotive vehicle, electric train, tram, etc.

[0003] In the automotive industry, high-voltage refers to voltages above 60 V. In the context of present invention high-voltage testing comprises testing cable harnesses with voltages equal or higher than 1000 V DC.BACKGROUND ART

[0004] Modern vehicles, especially hybrid (HEV) and electric vehicles (EV), comprise increasing number of power conduits and other wiring / cables. In majority cases said wiring is installed into the vehicles at early stage of their assembly, meaning that replacing faulty wiring and cables in many cases requires extensive disassembly of already installed parts. Faults in the cables include breakage of insulation, damaged or incorrectly installed connectors, presence of short circuit sources, such as wire burrs, loose copper strands etc.

[0005] There is increasing need for testing methods for electric vehicle cables and wiring harnesses (these include cables for charging ports, drive units, inverters and battery connections) of several new electric vehicles. But testing insulation integrity of these new cables proves to be problematic, because many of those cables contain only one electrical conduit and do not have any shielding to provide a reliable means to verify integrity of insulation with purely high-voltage testing. Therefore, present invention provides an alternative testing device and method.

[0006] This means high-voltage cables, high-voltage wiring harnesses and other conduits between charge port, battery pack and drive unit have become a common element in every electric vehicle.

[0007] Wiring harness testing has always been a key component in automotive manufacturing process, because most wiring harnesses are still hand built and manually assembled during final assembly of cars. In particular, reliable testing of the insulation of high-voltage cables is needed to make sure that the insulation has not been mechanically damaged during the manufacturing process. Any defect in the insulation may lead to an electric discharge, further deterioration of the insulation, fire hazard with accumulation of hazardous gases and risk of electric shock, therefore, the insulations of the cables must be properly inspected.

[0008] Most common testing methods are based on electrical testing, e.g., based on measuring resistance of the insulation. It would require, however, that an electrode is created around the length of the entire cable.

[0009] There are some alternative methods available to use electrical test for insulation integrity verification in single conduit cables without shielding.

[0010] Firstly, cable can be suspended in conductive liquid to provide measuring point against primary conduit to verify insulation integrity with high-voltage breakdown test. Alternatively, conductive mist can be used instead of liquid to provide means to measure insulation integrity against cable conduit.

[0011] Secondly, cable can be wrapped in a conductive foil, tape, mesh or other suitable electrically conductive cover to provide means to perform electrical breakdown test along the length of high-voltage cable.

[0012] Thirdly, entire wiring harness can be placed in sealed chamber filled with ionized gas and / or extremely low air pressure environment to provide means to perform electrical breakdown test. Such a solution is known from United States patent application US2022 / 0291274A1 (published 15.09.2022).

[0013] All these methods are extremely time consuming, cumbersome and have limited usability. In many cases wiring harnesses have non-shielded high-voltage cables installed in plastic carrier structures that are often used to protect cables and provide fixture points and correct positioning during assembly.

[0014] This means that wrapping the length of cable with conductive foil, tape, mesh or other suitable electrically conductive cover was not possible and suspending it in liquid would require elaborate custom vessel for each cable geometry. Using mist would require closed cabinet with controlled spray patterns and ventilation to clear residual mist after test is performed.

[0015] Liquid based solutions would also require rinsing off any conductive media residue after test is finished. Also, all conductive liquids propose a quality hazard if they somehow leak anywhere besides designated testing area and compromise the electrical properties of product being tested.

[0016] United States patent US5279147 (published 18.01.1994) discloses a method and device for locating disruptions, such as leak or fault in an electrical cable and determining extent thereof. In said method a testing device is used, comprising two connecting ports for mating hermetically to corresponding ends of tested cables.

[0017] According to said method, an interruptible pressurized gas is supplied to the cable's interstitial void space through said chambers, in both chambers flow rate of gas is measured to or from the interstitial void space of the tested cable.

[0018] Using said measurements, the location of the fault in the cable is determined and extent of the leakage. Said device is only intended to locate the disruption in the insulation. Said device does not allow testing electrical characteristics of the tested cable nor detect other problems with the tested cable.DISCLOSURE OF INVENTION

[0019] Present invention provides a wiring harness insulation testing device enabling testing both of electrical characteristics of tested wiring harness and detection of insulation faults in the tested harness (that is in the cable / cables in said harness) using a single testing device.

[0020] Invention disclosed provides a new solution for testing integrity of insulation in such non-shielded high-voltage wiring harnesses. Traditionally high-voltage test is used to verify insulation integrity. For cables with multiple conduits insulation defects are detected if there is electrical breakdown between conduits during high-voltage testing. Similarly, single conduit cables can be tested if they have conductive shielding. Then breakdown test using high-voltage is performed between the conduit and shielding to verify insulation integrity.

[0021] Present invention relates to a device for testing of insulation of electric cables having a conductive core, surrounded by an insulation and having at least one electrical connector at each end. For testing, the invention takes an advantage of the cable structure where insulation forms an elastic tube around the core consisting of conductive (for example copper) strands. There is always a void between said core and said insulation.

[0022] Testing device of the invention is based on this property of the cable. Essentially nonshielded high-voltage cables can be regarded as tubes made up of insulation material and their integrity can be verified with pressure test by a device comprising means for introducing negative or positive gas pressure inside the cable. Alternatively, cable can be sealed off from pressure regulated environment.TECHNICAL PROBLEM

[0023] Therefore, it is crucial to be able test quickly and reliably every wiring harness (e.g., power cables, etc.) to be installed into the vehicle / means of transport prior their installation.

[0024] In existing testing devices insulation is tested using high-voltage tests and other issues are tested using low-voltage tests, but those tests are carried out in separate devices. In high-voltage insulation tests usually effects of corona discharge are applied to find disruption in the insulation - said tests are performed on special test beds / tables.

[0025] However, using at least two separate testing devices for testing is time consuming as wiring harnesses must be installed and removed to and from both testing devices. Also, high- voltage corona discharge tests pose danger to the testing personal and to the electronic equipment connected to the harness due to the high-voltages used.

[0026] Therefore, there is a need for a testing device, which enables to carry out various tests for wiring harnesses in the single device quickly and safely, enabling testing both electrical connections and insulation in the same device and preferably simultaneously.TECHNICAL SOLUTION

[0027] Present invention provides a wiring harness insulation testing device, comprising a first testing chamber for receiving one end of tested wiring harness with an electrical connector and a second testing chamber for receiving another end of tested wiring harness with an electrical connector. Electrical connector in the present context is for example a male or female plug.

[0028] Each testing chamber comprises a chamber bottom and chamber top, said chamber top and bottom being hinged together and openable in a released state and lockable into a hermetically closed state around said electrical connectors and around the insulation at the ends of said wiring harness to be tested.

[0029] Preferably for hermetically closing said chamber top and bottom, an actuator is used, such as a pneumatic, hydraulic or electric actuator.

[0030] Each testing chamber comprises electrical testing means used for a high-voltage testing. In another embodiment of the invention, said electrical testing means comprises also low-voltage testing means, which are controlled by a control unit to perform low-voltage tests.

[0031] Additionally, each testing chamber comprises: an inlet connected to the means for generating negative or positive gas pressure inside said testing chamber; and means for measuring pressure in said testing chamber; a control unit, which is configured to perform high-voltage tests on said wiring harness with said electrical testing means; and where said control unit is configured to introduce negative or positive gas pressure into at least one of said testing chambers by the means for generating negative or positive gas pressure and to measure pressure in the testing chambers by said means for measuring pressure.

[0032] Said electrical testing means comprise high-voltage terminal and high-voltage electrode.

[0033] Said control unit is configured to detect pressure change over a predetermined period of time in at least one of said testing chambers by means for measuring pressure.

[0034] Testing of wiring harness is performed as follows:1) First end of the wiring harness with a plug is inserted into the receiving socket in the first chamber and the chamber is closed. At first closing is done mechanically by closing chamber top over the inserted plug in the chamber bottom and then chamber top and bottom are pressed pneumatically together to seal said chamber hermetically.2) Second end of the wiring harness with a plug is inserted into the receiving socket in thesecond chamber and the chamber is closed and said second chamber is closed hermetically as the first chamber.3) Pressurization of the first chamber takes place and pressure measurements are performed in the second chamber and measure values are compared with the predetermined values. It is important that the pressure applied in the first chamber is able to transfer inside insulation of wiring harness into the second chamber. Whenever cable insulation has penetrating damage, leaks are present in said damage area and predetermined pressure values are not achieved. Thus, test device determines cable insulation to be faulty and tested harness containing such cable with faulty insulation will not pass the test.4) Presence of required assembly elements (contacts) is checked.5) A high-voltage electrical test is performed check that the electrical connections of the wiring harness are within predetermined specifications and to check the quality of connections.6) A disruptive discharge test of high-voltage electrode of the chamber is performed to make sure, that no short circuit sources, such as wire burrs are present.

[0035] By providing a sealed connection at one end of the harness to be tested, and providing a second sealed connection to the other end of the harness to be tested, a pressure sensor connected to either said first connector or said second connector and control circuits for initiating source for negative or positive gas pressure to introduce gas into said void and for measuring pressure and / or pressure drop over time by said pressure sensor, and determining from said pressure and / or pressure drop whether the cable insulation has any mechanical defects.

[0036] The most challenging part is to create airtight seal at both ends of the non-shielded high-voltage cable, since they are attached to electrical connectors or terminals that come in various shapes and sizes. To form an airtight seal around the cable we created a pressure chamber built from two halves - chamber bottom and chamber top.

[0037] Each chamber has an adapter for positioning high-voltage connector inside the chamber, perimeter seal and cable seal. Locking mechanism is used for retaining the chamber in closed position and actuator is used to compress two halves together to form a sealed system.

[0038] Then pressure differential is applied inside the chamber via air inlet. Non-shieldedhigh-voltage insulation cable acts as a tube and air / gas under pressure will gradually move through the high-voltage insulation and create a pressure change in second chamber. This change can be measured and analysed.

[0039] It is obvious to the person skilled in the art, that the testing device according to the invention only works for a wiring harness with sufficient (measurable) air movement present between the ends of the cable or wiring harness being tested. In a cable or wiring harness having too small or tight cross-section, there is no measurable amount of air moving from one chamber to another.

[0040] Pressure chamber can be adapted to different high-voltage connectors by replacing bottom adapter half and top adapter half to fit a different high-voltage connector.

[0041] Pressure chamber can be adapted to different diameters of high-voltage cables by replacing bottom cable seal and top cable seal to fit a different high-voltage insulation.ADVANTAGEOUS EFFECTS

[0042] Device according to invention enables simultaneous testing both electrical connectors of the cable and insulation of the cable. There is no need to reposition tested wiring harnesses into different testing devices for different tests.

[0043] This saves time and effort used for testing. Thus, the testing device according to invention is more economical compared to known testing devices from the prior art.

[0044] In addition, because high-voltage tests are contained within corresponding testing chambers of the device, complexity of testing device is reduced, and same time safety of the device is increased.BRIEF DESCRIPTION OF DRAWINGSIn the following present invention is described in more detail manner with references to the accompanying drawings, where:Figure 1 depicts schematically a typical wiring harness, comprising a high-voltage cable having electrical connectors at both ends;Figure 2 depicts one end of the cable with connector;Figure 3 depicts schematically a test device comprising two test chambers that are closed around high-voltage connectors of the tested wiring harness;Figure 4 depicts a testing chamber of testing device of the invention in an opened state;Figure 5 depicts a testing chamber according to Figure 4 with test cable inserted into the receiving socket;Figure 6 depicts a testing chamber according to Figure 5 in an initial closing stage, where chamber top has been placed onto a chamber bottom;Figure 7 depicts a chamber according to Figure 6, where chamber bottom and chamber top are being sealed together around the end of the cable to be tested.MODE(S) FOR CARRYING OUT THE INVENTION

[0045] The electric drivetrain of an HEV or EV is mainly composed of a high-voltage battery, charge port, inverters, and motors. They are connected to each other with high- voltage wiring harnesses, such as depicted in Figure 1.

[0046] Typical high-voltage conduit in a wiring harness consists of single high-voltage cable with electrical connectors at each end, Figures 1 and 2.

[0047] The testing device of the invention comprises two identical testing chamber, one for each end of the tested wiring harness.

[0048] As can been from Figure 3, testing chamber comprises chamber bottom 1, chamber top 2, compression frame 3, actuator 4, adapter bottom half 5, adapter top half 6, bottom perimeter seal 7, top perimeter seal 8, bottom cable seal 9, top cable seal 10, hinge 11, actuator piston 12 and air inlet 13.

[0049] The high-voltage connector 14 of the tested wiring harness, including a high-voltage insulation 15 and high-voltage copper leads 16, is received between the adapter bottom half 5 and top half 6. The adapter bottom half 5 comprises high-voltage terminal 17 and high- voltage electrode 18.

[0050] High-voltage connector 14 is inserted in bottom adapter half 5 so that high-voltage insulation 15 is aligned with bottom cable seal 9. High-voltage connector 14 is electrically contacting high-voltage terminal 17.

[0051] Top chamber 2 is moved to closed position until it can be mechanically locked. High- voltage connector 14 is now properly aligned. Cut view shows high-voltage insulation 15 and high-voltage copper leads 16 acting as a pneumatic hose, where airflow can occur.

[0052] Actuators 4 move compression frame 3 in downward motion to create airtight system between bottom perimeter seal 7, top perimeter seal 8, high-voltage insulation 15, bottom cable seal 9 and top cable seal 10.

[0053] Airflow is introduced in air inlet 13 to create overpressure inside test device. Due to pressure differential some of air starts flowing inside high-voltage insulation 15 between high-voltage copper leads 16.

[0054] At this stage also electrical and other tests can be performed. High-voltage terminal 17 contacting high-voltage connector 14 is used to test electrical parameters of cable circuit.

[0055] High-voltage electrode 18 is used to detect loose copper strands by means of electrical breakdown test. For example, high-voltage testing is performed using voltages starting from 2 kV DC.

[0056] When pressure differential is introduced in one chamber, it is transferred to the second chamber via high-voltage insulation that acts as a tube.

[0057] This gas flow leads to change in pressure at other end of the system, where it can be measured. When high-voltage cable has insulation damage (lacerations, punctures), system detects pressure loss between chambers.INDUSTRIAL APPLICABILITY

[0058] Proposed testing device provides a reliable means of testing insulation integrity using gas pressure while simultaneously all electrical and mechanical tests are performed inside the chambers.LIST OF REFERENCE NUMBERS

[0059] 1 chamber bottom2 chamber top3 compression frame4 actuator5 adapter bottom half6 adapter top halfbottom perimeter seal top perimeter seal bottom cable seal top cable seal hinge actuator piston air inlet high-voltage connector high-voltage insulation high-voltage copper leads high-voltage terminal high-voltage electrode

Claims

Claims1. A wiring harness insulation testing device, comprising: a first testing chamber for receiving one end of tested wiring harness with an electrical connector and a second testing chamber for receiving another end of tested wiring harness with an electrical connector; each testing chamber comprising a chamber bottom and chamber top, said chamber top and bottom being hinged together and openable in a released state and lockable into a hermetically closed state around said electrical connectors and around the insulation at the ends of said wiring harness to be tested; where each testing chamber comprises electrical testing means, characterized in that, each testing chamber comprises: an inlet connected to the means for generating negative or positive gas pressure inside said testing chamber; and means for measuring pressure in said testing chamber; a control unit, which is configured to perform high-voltage tests on said wiring harness with said electrical testing means; and where said control unit is configured to introduce negative or positive gas pressure into at least one of said testing chambers by the means for generating negative or positive gas pressure and to measure pressure in the testing chambers by said means for measuring pressure.

2. Device according to claim 1, characterized in that, the electrical testing means comprise high-voltage terminal and high-voltage electrode.

3. Device according to claim 1, characterized in that, said control unit is configured to detect pressure change over a predetermined period of time at least one of said testing chambers by means for measuring pressure.

4. Device according any one of the preceding claims, characterized in that, electrical testing means comprise low-voltage testing means.

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