Patent Description:
Electrical components such as couplings, connectors, terminals and fuses are tested during assembly to ensure that they are inserted correctly. A process control system may involve the testing of insertion forces during assembly to establish correct insertion. The withdrawal force may also be tested during an extraction or disassembly process. The application of a consistent insertion force is essential to ensure the security of the electrical connection and to avoid unintended release of the connectors in use.

A known method for testing insertion forces uses insertion tools having electrical micro switches with springs maintaining a contact gap of the switch. The spring is selected such that compression under a given insertion force results in closure of the switch, which indicates that the required insertion force has been applied. Connection security is also reliant on the point of application of the insertion force. If the force is applied off-centre, or away from the optimum point of application, it may be imbalanced and cause the connector to move out of correct alignment. As a result, the connector may not insert correctly and securely despite the application of the required insertion force.

Automotive connectors experience significant vibrations and acceleration forces during operation of a vehicle. Such connectors must therefore be properly seated and connected to prevent connection failure in use. An installation procedure for an automotive electrical component such as a fuse box may require an operator to apply a required verified insertion force, ensure that the component has 'clicked' into location, and then pull the wires of the component to confirm secure seating. This test is referred to as a 'push-click-tug' test. Following completion of the push-click-tug test a connector presence assurance (CPA) test is conducted to confirm that an electrical connection has been established and that there is electrical continuity.

In certain conditions it is possible that the connector may not be fully and accurately inserted despite each of the required testing steps being completed to the satisfaction of the operator. The insertion force and CPA tests may indicate that the connector has been correctly inserted despite the connector being misaligned or not fully seated. As a result, the connector may become disconnected in use, or during installation in the vehicle.

Document <CIT> discloses an apparatus, systems, and methods which operate to receive measurements corresponding to a plurality of forces sensed substantially simultaneously at a substantially planar, weight-bearing measurement surface.

It is therefore desirable to provide an improved test apparatus, which addresses the above described problems and/or which offers improvements generally.

According to the present disclosure there is provided a test apparatus for verifying plugging force as described in the accompanying claims. In an aspect of the disclosure there is provided a test apparatus for verifying plugging force during assembly of a first electrical component having one or more electrical connection points for receiving one or more corresponding second electrical components in a push fit arrangement. The test apparatus comprises a load plate having a support surface and orthogonally arranged first and a second axes defined parallel to the support surface. A holder is provided for retaining the first electrical component on the load plate. A plurality of load cells support the load plate and are arranged at spaced locations about the load plate such that a plugging force applied to the first electrical component retained on the load plate, via the second electrical component, in a direction perpendicular to the support surface of the load plate is transferred to the plurality of load cells. A processor is provided for receiving load cell data from the load cells corresponding to the force applied to each load cell respectively. The processor is operative to determine the magnitude of the plugging force and the location at which the plugging force is applied to the first electrical component relative to the first and second axes of the load plate based on the load cell data and the location of the load cells relative to the load plate.

The first electrical component may be a fuse box and the second electrical component may be one or more fuses, which may include relays, connectors or other attached components. The first and second axes are orthogonal x,y axes defined across the surface of the load plate. The term "holder" refers to any component capable of holding the first electrical component in a fixed location on the load plate during insertion of the second electrical components. The holder is also preferably able to hold the first electrical component in position on the load plate when a pulling force is applied to the second electrical component. The processor preferably comprises a computer running software for performing the operations required of the processor. The term 'load cell data' may comprise electrical signals, digital information or any other load cell output.

The processor is preferably programmed with location information relating to the location of the one or more sockets of the first component on the load plate when the first electrical component is retained in the holder. The location information is x,y coordinates of each socket and the location at which the pushing force must be applied to each fuse or other component when it is inserted into the socket. The processor is operative to compare the determined x,y location of the point of application of the plugging force with the desired location and provide an output based on said comparison. The output may be an indication as to whether the plugging force was applied at the correct x,y location or not. The required x,y location may have a tolerance radius within which the point of the plugging force may be considered compliant.

The processor may be programmed with force information relating to the desired magnitude of the pushing force for each socket and is operative to compare the determined magnitude of the plugging force for each socket with the desired plugging force and provide an output based on said comparison. The desired magnitude is a minimum force threshold that must be met to provide suitable assurance that the second component has been fully seated within the socket and may be defined by the component manufacturer. The processor may also determine whether a maximum force threshold is reached above which there is risk of damage to first and/or second components and may provide an alert if the maximum threshold is reached.

A visual display unit may be provided, and the processor may be operative to display on the visual display unit a visual representation of the load plate and the first electrical component and to generate and display a visual indicium of the location of the plugging force. The visual representation may be a pre generated image such as a photograph or graphical representation of the load plate and first electrical component stored on a computer readable memory of the processor or may be a live image captured by a camera. The image may alternatively comprise an image of the first electrical component located on a 2D grid representative of the x,y coordinate of the load plate. The indicium may be a graphical image superimposed on the visual representation indicating the point of application of the plugging force. The processor may also be operative to generate and display an indicium of the magnitude of the plugging force. The force indicium may be separate to the location indicium or may be defined by the first indicium. For example, the first indicium may vary in size or colour depending on the magnitude of the force.

The load cells are preferably mounted to a support structure at a first proximal end and are connected to the load plate at a second distal end. The support structure may be a support frame, a base plate located beneath the load cell or any other structure suitable to support the load cells while they hold the load plate in a suspended arrangement.

The load plate may comprise a third load axis (z-axis) arranged perpendicular to the first and second axes, and the load cells are arranged to support the load plate in the direction of the third load axis. Preferably the load plate is horizontally arranged with the x,y axes being horizontal axes and the z axis being a vertical axis.

The load cells may comprise a plurality of strain gauges mounted on opposing upper and lower surfaces thereof. The load cells may be operative to determine the direction and the magnitude of a force applied to the load plate in the third load axis based on the output of the strain gauges.

The processor may be operative to determine, based on whether the load cell signals are positive or negative, whether the force applied to the load plate is a plugging force directed towards the support surface of the load plate or a pulling force directed away from the support surface of the load plate, the plugging and puling forces being in the third load axis.

The processor may be operative to verify a test procedure comprising a first step of inserting a second electrical component into a socket of the first electrical component and applying a plugging force to the second electrical component and a second step of pulling the second electrical component to ensure the second electrical component is properly seated in the socket. The processor is operative to verify the first step by determining the magnitude and location of the plugging force and comparing each with a required plugging force magnitude threshold and location relative to the first and second axes respectively, and wherein the processor is operative to confirm that the first steps has been conducted correctly if the plugging force is determined to have been applied at the correct location and to have met the plugging force threshold. The processor determines the x,y coordinate of the location at which the plugging force is applied, and compares this x,y location with the x,y co-ordinates of the required point of application to establish whether the plugging force has been applied at the correct location.

The processor may be operative to verify the second step by determining the magnitude of the pulling force and comparing this with a required pulling force threshold. The processor is operative to confirm that the second step has been conducted correctly if the pulling force is determined to have been applied at the correct location and to have met the pulling force threshold. The processor may also determine the location at which the pulling force is applied, which may be used to confirm for example that the correct fuse has been pulled.

The load plate may comprise a peripheral edge and the load cells are arranged about the periphery of the load plate. The load cells are preferably located beneath the load plate with the load plate being mounted thereon. The load plate may comprise a plate and support frame to which the plate is mounted. The load cells are preferably connected to the support frame of the load plate.

Each load cell is preferably mounted at a first end to a support element which may be a rigid structure, and extends from the support element in a cantilever arrangement. The opposing second end is connected to the load plate. Preferably the load cells and the support elements are located beneath the load plate and within the perimeter or footprint of the load cell.

In another aspect of the invention there is provided a method of conducting a plugging force verification test comprising:.

The method may further comprise, following insertion of the second electrical component, applying a pulling force to the second electrical component and verifying whether the pulling force meets a pulling force threshold and is applied at a required location relative to the first and second axes.

The method may further comprise displaying an image of the electrical component on a display unit and indicating on the display the location and/or magnitude of the plugging force and/or pulling force.

The method may further comprise providing a feedback signal to the operator to confirm whether the plugging force threshold has been reached.

The method may further comprise providing an indication that the plugging force verification test has been successfully completed if it is determined that the plugging force threshold has been reached and the plugging force was applied at the correct location.

The present disclosure will now be described by way of example only with reference to the following illustrative figures in which:.

The following description presents exemplary embodiments and, together with the drawings, serves to explain principles of the disclosure. In some cases, several alternative terms (synonyms) for structural features have been provided but such terms are not intended to be exhaustive.

Descriptive terms should also be given the broadest possible interpretation; e.g. the term "comprising" as used in this specification means "consisting at least in part of" such that interpreting each statement in this specification that includes the term "comprising", features other than that or those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted in the same manner. Directional terms such as "vertical", "horizontal", "up", "down", "upper" and "lower" are relative terms that may be used for convenience of explanation usually with reference to the illustrations and are not intended to be ultimately limiting if an equivalent function can be achieved with an alternative dimension and/or direction.

The description herein refers to embodiments with particular combinations of configuration steps or features. However, it is envisaged that further combinations and cross-combinations of compatible steps or features between embodiments will be possible. The description of multiple features in relation to any specific embodiment is not an indication that such features are inextricably linked, and isolated features may function independently from other features and not necessarily require implementation as a complete combination.

Referring to <FIG>, a system for testing the insertion of electrical automotive components comprises a horizontally arranged load plate <NUM> mounted on an inner frame <NUM>. The load plate <NUM> includes a holder <NUM> located on its upper surface for receiving and holding a fuse box <NUM>, having a plurality of electrical connection points <NUM> in the form of sockets to which a plurality of corresponding fuses are to be connected. However, it will be appreciated that the present disclosure could be applied to any electrical component or apparatus configured to receive one or more corresponding electrical connectors. The inner frame <NUM> comprises four frame members <NUM> arranged in a square or rectangular formation. The frame members comprise a pair of first and second frame members 8a,8b arranged in parallel with each other and a pair of third and fourth frame members 10a,10b arranged in parallel with each other. The first and second frame members 8a,8b are connected to the third and fourth frame members 10a,10b and arranged orthogonally thereto.

The inner frame <NUM> is mounted to and suspended within an outer frame <NUM>. The inner frame <NUM> is mounted to the outer frame <NUM> by a plurality of load cells <NUM> spaced around the inner frame <NUM>. A first load cell <NUM> and second load cell <NUM> are connected to the first frame member <NUM>. The first and second load cells <NUM>,<NUM> are spaced from each other along the first frame member <NUM> and are located at opposing ends of the first frame member <NUM> proximate the third and fourth 10a,10b frame members respectively. The first and second load cells <NUM>,<NUM> have an upper surface <NUM> and a lower surface <NUM>. The first frame member 8a is mounted to the each of the first and second load cells <NUM>,<NUM> at a spaced position above the upper surface <NUM> of each load cell <NUM>,<NUM>.

A guide pin <NUM> connects the first frame member <NUM> to each load cell <NUM>,<NUM>. The guide pin <NUM> is rigidly secured to the inner end of the load cell <NUM>,<NUM> and extends through the upper surface <NUM>,<NUM>. A first spring <NUM> is located about the guide pin <NUM> between the upper surface <NUM>,<NUM> of the load cell <NUM>,<NUM> and the lower surface of the first frame member 8a. The guide pin extends through the first frame member 8a and has an enlarged diameter head <NUM> located at its upper end. A second spring <NUM> is located about the guide pin <NUM> between the upper surface of the first frame member <NUM> and the head <NUM>. The first frame member 8a is slidingly supported on the guide pins <NUM> and is able to move up and down away from and towards the load cells <NUM>,<NUM>. The first and second springs <NUM>,<NUM> act as dampers as the first frame member <NUM> is urged downwardly or upwardly. Damping the connections between the load cells and inner frame, rather than providing a rigid connection, ensures that the load cells do not require recalibration following installation. A dampened connection also reduces tension in the frame and ensure an effective force distribution between load cells.

A third load cell <NUM> and fourth load cell <NUM> are connected to the second frame member 8b. The third load cell <NUM> and fourth load cell <NUM> are spaced from each other along the second frame member 8b and are located at opposing ends of the second frame member 8b proximate the third and fourth frame members <NUM>,<NUM> respectively. The load cells <NUM>,<NUM> have an upper surface <NUM> and a lower surface <NUM>. The second frame member 8b is mounted to the each of the third and fourth load cells <NUM>,<NUM> at a spaced position above the upper surface <NUM> of each load cell <NUM>,<NUM>. Similarly to the first frame member 8a, a guide pin <NUM> connects the second frame member 8b to each load cell <NUM>,<NUM>. The guide pin <NUM> is rigidly secured to the inner end of the load cells <NUM>,<NUM>. A first spring <NUM> is located about the guide pin <NUM> between the upper surface <NUM>,<NUM> of the load cell <NUM>,<NUM> and the lower surface of the second frame member <NUM>. A second spring <NUM> is located about the guide pin <NUM> between the upper surface <NUM> of the second frame member 8b and the head <NUM>. The second frame member 8b is slidingly supported on the guide pins <NUM> and is able to move up and down away from and towards the load cells <NUM>,<NUM>.

The load cells <NUM>,<NUM>,<NUM>,<NUM> are tensometric beams and are connected to the inner frame <NUM> at their inner ends and at their outer ends to the outer frame <NUM>. The outer ends of the load cells are connected to the outer frame in a cantilever arrangement, with the outer end of each load cell <NUM>,<NUM>,<NUM>,<NUM> being mounted on an upper surface of the outer frame <NUM> and projecting inwardly from the outer frame <NUM> towards the inner frame <NUM>. The distance between the point of connection of each load cell <NUM>,<NUM>,<NUM>,<NUM> with the outer frame <NUM> and the point of connection of each load cell <NUM>,<NUM>,<NUM>,<NUM> with inner frame <NUM> defines a lever arm.

The holder <NUM> is arranged to receive and hold the fuse box <NUM> such the fuse box <NUM> is secured rigidly within the holder <NUM> and relative to the inner frame <NUM>. In this way, forces applied to the fuse box <NUM> are transferred to the inner frame <NUM> via the load plate <NUM>. The load plate has a first horizontal x axis and a second horizontal y axis orthogonal to the x axis. The first and second inner frame members 8a,8b are arranged along the x axis and the third and fourth frame members 10a,10b are arranged along the y axis. A vertical z axis is defined orthogonally to the x and y axes. Vertical forces applied to the fuse box <NUM> in z axis are transferred to and distributed between the load cells <NUM>. The load cells <NUM>,<NUM>,<NUM>,<NUM> are configured and operative to measure the value of force vector applied to the load cell in z axis. The load cells <NUM>,<NUM>,<NUM>,<NUM> are configured to measure the z axis force vector in both a positive direction corresponding to a downward 'pushing' force and a negative upwards 'pulling' force.

The principle of operation of the load cells <NUM>,<NUM>,<NUM>,<NUM> to measure the force applied to the load plate <NUM> relies on strain gauges provided on the outer surfaces of the load cells <NUM>,<NUM>,<NUM>,<NUM> as shown in the <FIG>. The strain gauges may for example comprise bonded metallic strain gauges consisting of very fine wires or a grid of metallic foil. A first pair of strain gauges <NUM>,<NUM> are mounted in a spaced relationship along the length of the upper surface of each load cell <NUM>,<NUM>,<NUM>,<NUM>. A second pair of strain gauges <NUM>,<NUM> are mounted in a spaced relationship along the length of the lower surface of each load cell <NUM>,<NUM>,<NUM>,<NUM>.

The strain gauges of each load cell <NUM>,<NUM>,<NUM>,<NUM> are connected respectively in a Wheatstone bridge as illustrated in <FIG>. The output voltage Vo is measured as the difference between voltage output'+' and output '-'and varies according to the load applied load cell. As shown in <FIG>, each load cell <NUM>,<NUM>,<NUM>,<NUM> is connected to a dedicated PCB <NUM>,<NUM>,<NUM>,<NUM> that is configured to function as a load cell amplifier. The output voltage signal Vo from each load cell <NUM>,<NUM>,<NUM>,<NUM> is amplified by the dedicated load cell amplifier <NUM>,<NUM>,<NUM>,<NUM>, which converts the measured analogue output Vo to a digital signal. The digital output signal from each load cell amplifier <NUM>,<NUM>,<NUM>,<NUM> is transmitted to a micro controller <NUM>. The microcontroller converts the signal from each load cell amplifier <NUM>,<NUM>,<NUM>,<NUM> to a value indicative of the load applied to each respective load cell <NUM>,<NUM>,<NUM>,<NUM>.

The force applied to the component received with the holder <NUM> is transferred to the load plate <NUM>. The applied force is then divided between each of the load cells <NUM>,<NUM>,<NUM>,<NUM>. The x,y location of the applied force on the load plate can be determined based on the distribution of the force across each of the load cells <NUM>,<NUM>,<NUM>,<NUM>. Referring to Figure XIII, a force F1 is applied to the load plate <NUM> at an x,y location. The x,y axes are arranged relative to the load plate <NUM> and the load cells <NUM>,<NUM>,<NUM>,<NUM> such that the first and fourth load cells <NUM>,<NUM> (A,D) and the second and third load cells <NUM>,<NUM> (B,C) are arranged at a common y locations respectively. The third and fourth load cells <NUM>,<NUM> (C,D) and the first and second load cells <NUM>,<NUM> (A,B) are arranged at a common x locations respectively. The first and fourth load cells <NUM>,<NUM> (A,D) are arranged at xo and third and fourth load cells <NUM>,<NUM> (C,D) are arranged at yo.

During application of the applied force the inner frame <NUM> remains stationary. Therefore, the sum of torque applied across the load cells <NUM>,<NUM>,<NUM>,<NUM> zero. The value of the force vector is the sum of the readings of all four load cells <NUM>,<NUM>,<NUM>,<NUM>: <MAT>.

The x,y coordinates of the applied force are determined by calculating what part of the total force vector is measured by the load cells at common x and y locations respectively from the xo,yo axis. The x,y are co-ordinates are therefore calculated as follows: <MAT> <MAT>.

The load cells <NUM>,<NUM>,<NUM>,<NUM> are arranged such that the output of each load cell <NUM>,<NUM>,<NUM>,<NUM> is positive if the force is applied is a positive i.e. downward direction and negative if the force is applied in the reverse upwards direction. The load cells <NUM>,<NUM>,<NUM>,<NUM> may therefore be used to determine the magnitude, location and direction of applied forces during both 'push' test and a 'pull' test.

The microcontroller <NUM> may be an ESP <NUM> microcontroller and is configured sample date from the load cell amplifiers <NUM>,<NUM>,<NUM>,<NUM> at a high frequency and to process the load cell amplifier data to calculate the x,y coordinates and magnitude of the applied force. The microprocessor data is supplied to a PC that provides a user interface for conducting the 'push-click-tug' tests. The PC is programmed with information relating to the shape and size of the fuse box or other component, the location of the sockets to which the connectors are to be supplied, and the required location of the applied force for each connector. The PC is also programmed with the x,y position of the holder <NUM> and fuse box on the load plate <NUM>, and the x,y location of each socket.

Prior to the insertion of a component the load cells are auto tared to zero the readings of each and account for the weight of the load plate <NUM> and the fuse box. The auto tare function is operated by the microcontroller. The auto tare function of the microcontroller comprises detecting a stabilised reading from each load cell, indicating that the pushing or pulling forces have stopped, and auto taring the stabilised reading is detected. The auto tare procedure is completed following each push-click-tug test.

When a fuse is inserted, the x,y position of the applied force is calculated. The position and magnitude of the applied force is cross references with the required force location and magnitude for the respective fuse. It is determined whether the applied force is of sufficient magnitude and applied at the correct location. The user also established by manual and aural feedback whether the fuse has clicked into location. The use then applies a pulling force to fuse. The pulling force is also detected and cross referenced to determine whether it is of sufficient magnitude and applied at the correct location. If it is determined that the insertion (push) and retraction (pull) forces were applied and the correct locations and were of sufficient magnitude, a positive signal is generated indication that the test was conducted correctly.

The PC may additionally be provided with a graphical representation of the load plate and the fuse box, which may be a pre-loaded image or a live capture image of the load plate <NUM> from a camera. The image of the load plate is overlaid with an x,y grid and features of the image, including the periphery of the fuse box and the sockets are assigned x,y coordinates. A display image is generated comprising an image of the fuse box on the load plate <NUM>, on which the location of applied force is represented based on the calculated x,y position. This real time visualisation of the measured force vector relative to the fuse box provides immediate feedback to the operator. The system may be configured to provide audio and/or visual feedback of a successful or unsuccessful completion of the test. The software may be configured to enable to operator to vary parameters such as force thresholds and other settings.

The visual display provides may provide guidance to an operator during testing, for example indicating the required location of the applied force and/or the required force direction for a given test step, and verify the correct application of each step ness.

The PC may be programmed with the configuration data for a range of electrical components and a range of corresponding test procedures and protocols. The system can therefore be adapted for applying any component plugging force verification test.

In an alternative embodiment, as shown in <FIG>, a load plate <NUM> is mounted on a load plate frame <NUM>. A holder <NUM> located on the upper surface of the load plate <NUM>. The holder <NUM> has a recess shaped to receive a fuse box <NUM>, having a plurality of sockets <NUM> to which a plurality of corresponding fuses are to be connected. The load plate frame <NUM> comprises four frame a pair of first and second frame members 8a,8b arranged in parallel with each other and a pair of third and fourth frame members 110a,110b arranged in parallel with each other. The first and second frame members 8a,8b are connected to the third and fourth frame members 10a,10b.

Load cells <NUM>,<NUM>,<NUM>,<NUM> are mounted to a base plate <NUM>. The base plate <NUM> is located beneath the load plate <NUM> and load plate frame <NUM>. It will be appreciated however that in other embodiments the load plate may be supported directly on the load cells and my not require a load plate frame, with the load cells being connected directly to the lower surface of the load plate rather than a load plate frame. <FIG> shows base plate <NUM> and load cells <NUM>,<NUM>,<NUM>,<NUM>, with the load plate <NUM> represented in dashed line. The load cells <NUM>,<NUM>,<NUM>,<NUM> are each mounted to the base plate <NUM> by a rigid support block <NUM> that spaces the first end of the load cell <NUM>,<NUM>,<NUM>,<NUM> from the base plate <NUM>. The load cells <NUM>,<NUM>,<NUM>,<NUM> extend horizontally from the respective support <NUM> in a cantilever arrangement. The first and second load cells <NUM>,<NUM> are longitudinally aligned with the first frame member 108a and the edge of the load plate <NUM>. The first load cell <NUM> is spaced beneath the first frame member 108a and is connected to a first end of the first frame member 108a by a first pair of rubber dampers <NUM>. The support block <NUM> is located inwardly of the first end along the length of the first frame member 108a. The second load cell <NUM> is similarly spaced beneath the first frame member 108a and is connected to a second end of the first frame member 108a by a second pair of rubber dampers <NUM>. The support block <NUM> of the second load cell <NUM> is located inwardly of the second end along the length of the first frame member 108a. The first and second dampers <NUM>,<NUM> provide a dampened connection between the first frame member 108a and the load cells <NUM>,<NUM>.

Claim 1:
A test apparatus for verifying plugging force during assembly of a first electrical component having one or more electrical connection points (<NUM>) for receiving one or more corresponding second electrical components in a push fit arrangement, the test apparatus comprising;
a load plate (<NUM>) having a support surface and orthogonally arranged first and second axes defined parallel to the support surface;
a holder (<NUM>) for retaining the first electrical component on the load plate;
a plurality of load cells (<NUM>, <NUM>, <NUM>, <NUM>) supporting the load plate arranged at spaced locations about the load plate such that a plugging force applied to the first electrical component retained on the load plate in a direction perpendicular to the support surface of the load plate is transferred to the plurality of load cells;
a processor (<NUM>) for receiving load cell data from the load cells corresponding to the force applied to each load cell respectively;
wherein the processor is operative to determine the magnitude of the plugging force and the location at which the plugging force is applied to the first electrical component relative to the first and second axes of the load plate based on the load cell data and the location of the load cells relative to the load plate.