Project 2

Backdoor wiring harness assembly -Project #2

Route the Wiring harness on the Given car body and Prepare to flatten the view drawing in CATIA V5. Application of all Packaging rules, Industry best practices studied in this course shall be demonstrated in design. Apply Protection coverings as required.

Available connector 3D data can be used, or you can download the connectors from www.te.com

Prepare & Submit all necessary reports like clearance, Clipping/Clamping selection, Harness fixing requirements, Harness continuity, and Assumptions if any along with CATIA 3D data.

wiring harness design of the car

sample images of the backdoor wiring harness.

OBJECTIVE

• Define all the mechanical connectors electrically and save them in the Catalogue.
• Place required Connecters on the Back door CAD data.
• Place Fir Tree clips at the required position by following the packaging rules.
• Create the Wiring Harness Routing with all the electrically defined connectors and mounting equipment.
• Create branching points at required locations to create sub-branches and connect to various connectors in the geometrical bundle.
• Apply Protection coverings as required.
• Create Wiring harness flattening for the final geometrical bundle.
• Using the drafting workbench, create a drawing sheet with the flattened wiring harness.

Important packaging rules and best practices to be considered during wire harness routing and placing of the clips and clamps are as follows –

• The distance between two clamps on a straight branch should be a maximum of 200mm.
• The minimum branch length should be 50mm.
• The minimum distance between the clip and the nearest branching point should be 25mm.
• The minimum distance between two straight connection points should be 200mm.
• The minimum distance between two breakout points should be 50mm.
• To limit the number of branches from a single branch point to 4.
• Enough clip clamps shall be provided to ensure positive clearance with surroundings and the safety of the wiring harness.
• Fir tree clips and other clips can be added to the Geometric bundle as they are electrically defined and are part of the Wire harness routing and should be provided with the Wire bundle package.
• Enough slack should be provided to the wiring harness which helps it not to get damaged during the opening and closing of the Back Door.
• Easy manufacturing, installation, removal, and maintenance have to be considered while designing the wire harness.
• The wire routing should be done keeping in mind the cost-effectiveness of the bundle package.
• To avoid the harness routing and clipping in blind zones of the operator during the assembly and the service.
• To provide proper slack at end connectors so that there will be no tension on the wire bundle.
• To avoid sharp edges on the sheet metal parts and if it is not possible then provide protection parts to prevent damage of the wire bundle.
• Routing through small structural holes and openings shall be avoided. To minimize chaffing and handling of the wiring harness during installation.
• To provide separate branch points for separate connectors to ensure Poka-Yoke.
• The bend ratio for all the bundle segments is considered to be 1.4

To download the Back Door CAD data from the given source.

Creating Holes on the given Back door data for reference purposes.

Here in this project, I have created Holes in the Flanges on the upper right corner of the back door for routing the harness properly into the back door assembly from the Car body part. It is considered a critical region that affects on closing and opening of the back door.

Then modified on the outer panel sheet metal surface where the Number plate holder and its light assembly are going to be fixed.

Creating the context assembly

Context assembly is nothing but the product file which contains the back door 3D-CAD data and the back door geometrical bundle. Here the geometrical bundle product contains all the connectors and clips which are electrically defined for the assembly.

• Create a new product file and rename it as Back door harness assembly context.

Now add the back door CAD data into the context assembly and also create the geometrical bundle product file inside the context assembly.

Define the geometrical bundle product file electrically using the geometrical bundle command.

Add the required suitable Connectors from the Connectors Catalogue.

Back Door Harness Assembly requires the following connection connectors

1. Interconnection Connector – 1
2. Top mounted stop light connector – 1
3. Defogger connectors – 2
4. Brake Light Assembly Connections – 2(LH and RH)
5. Number plate Light Connections – 2
6. Wiper motor Connection - 1
7. and required Mounting Equipments

Interconnection Connector C-776438-4

This Connector is already used and defined as an Electrical component for project-1, so for this project-2 is also taken from the catalog.

4Pole Connector_C-1563689-1 used for Brake Light assembly connections and Wiper motor connection

This connector C-282080-1 is used for defogger and numberplate connections

This connector C-173090-1 for high Mount Stop Light

Position the fir tree clips to the required locations to ensure proper harness routing throughout the Assembly.

Ensure no fouling of the harness to the back door sheet metal components.

Enough clamps shall be provided to ensure positive clearance with the surroundings and the safety of the wiring harness. The distance between two clamps/clips on a straight branch should be a maximum of 200mm. the clamping requirements should be decided based on the harness bending and mounting arrangements.

Creation of Wiring Harness Routing

Add branch points at a minimum of 25mm distance from clips and clamps to create new sub branches connecting various connectors.

The minimum length of bundle should be 50mm.

Now, the car tail gate assembly is ready for the bundle routing as shown in below image

We have activated Geometrical bundle product file from the context assembly to create new multi-branchables.

First, we have started bundle routing from interconnection connector to the nearest Mounting clip available and the continue to add multibranchabe bundles to achieve the required harness bundle. Main bundle harness diameter is considered as 15mm.

Then create a branch point to route the sub-routing bundle segment to the Top mount brake lamp connector. Fir tree clips are added in between the branch point and top mount brake lamp connector to ensure proper and safe routing. Bundle diameters are considered as 5mm.

Add a clip on the sheet metal in between the main harness bundle and number plate connector connections. This will improve the routing and prevent the bundle from unwanted fouling with sheet metal components.

final geometrical bundle

Adding Protective Cover (COT Tubes)

After bundle routing, we have to add a protective covering to the harness bundle so that it will get protected from damage.

The harness bundle should be protected with a flexible rubber cover at the interconnection region where it is a critical place and subjected to opening and closing of the door. There are more possibilities to damage the wiring harness if no proper protection coverage is provided.

sample images from Skoda car

Geometrical Bundle after applying COT tubes

Corrugated conduits and protective hoses with various properties, from heat resistance through abrasion protection and impact strength to noise reduction, protect valuable cables against all unfavorable external influences.

Slit COT tubes are provided for protecting the harness from physical and other environmental damages that can occur in the long run.

Start or End Extrimities at the Connector bundle entry side should be given a gap of 30mm

The selection of corrugated tubes is by the wiring harness routing bundle diameter and temperature resistance requirements.

ELECTRICAL CONTINUITY CHECK

We need to ensure that the entire bundle is fully connected.

Go to edit and then click on the search command.

Go to advanced

Select workbench as electrical, type as bundle segment, and attribute as Fully connected

The select result should be TRUE or FALSE and click search to see the connectivity analysis result

For now, we will select "TRUE" and search for results. All the bundle segments are highlighted and found showing that all the bundle segments are electrically connected.

WIRING HARNESS FLATTENING

The wiring harness Bundle packaging process is done. Now we need to convert the geometrical bundle into a flattened wiring harness in the Electrical Harness Flattening Workbench.

To create the Flattened Harness, we need to create a new product file and switch it into the electrical harness flattening workbench.

Now we need to define the Harness Flattening Parameters, save it in the same folder with all other files of the back door harness project and then Extract the geometric bundle from the wiring harness context product file.

Then select all the branches and flatten the entire Geometric bundle.

Flattening Wiring Harness View in Drawring Sheet

Create a Drawing File for the flattened harness product.

First, we need to make sure that in the flatten parameter settings bundles and protective coverings have different graphical representation which are

Bundle Segments – Single line representation

Protective coverings – Double line representation.

Create a new drawing file in the drafting workbench

Insert the flattened harness product into the drawing sheet using view option and selecting the front view command.

Final Back Door Wiring Harness Flattening Drawing

A car back door wiring harness assembly has been successfully completed considering all the packaging rules and industry standards, Wiring harness flattening and Flattened view drawing preparations are also done by using CATIA v5 software.