Project 1

Aim:To route the wiring harness of given Engine model and prepare flatten view drawing in CATIA V5. Apply all packaging rules and industry best practices.

INTRODUCTION:

WIRING HARNESS OR CABLE HARNESS:

A cable harness, also known as a wire harness, wiring harness, cable assembly, wiring assembly, or wiring loom, is an assembly of electrical cables or wires which transmit signals or electrical power. The cables are bound together by a durable material such as rubber, vinyl, electrical tape, conduit, a weave of extruded string, or a combination thereof.

Cable harnesses are usually designed according to geometric and electrical requirements. A diagram is then provided (either on paper or on a monitor) for the assembly preparation and assembly.

The wires are first cut to the desired length, usually using a special wire-cutting machine. The wires may also be printed on by a special machine during the cutting process or on a separate machine. After this, the ends of the wires are stripped to expose the metal (or core) of the wires, which are fitted with any required terminals or connector housings. The cables are assembled and clamped together on a special workbench, or onto a pinboard (assembly board), according to design specification, to form the cable harness. After fitting any protective sleeves, conduit, or extruded yarn, the harness is either fitted directly in the vehicle or shipped.

Assumpions and packing rules :

• Wiring harness routing shall provide ease in manufacturing, accessibility, easy removal and easy maintenance of attached equipments and routing harness.
• Wiring harness should be routed in such a way that it is easy to assemble on a vehicle.
• Wiring harness should be kept away from sharp environments like sheet metal brackets, panel edges, corners etc.
• Avoid harness routing and clipping in blind zone of operator during harness during installation.
• Ensure that routing meets the clearance requirements with the different surrounding parts.
• Routing shall provide enough slack for each branch to avoid additional stress on wire and terminal crimping joints but ensure that extra slack does not cause wiring harness foul with surrounding parts and impact desired clearance requirements.
• Enough clamps should be provided to ensure the positive clearance with surrounding and safety of wiring harness.
• Use of plastic guided channels are recommended to meet the clearances in critical areas if it is difficult to achieve by use of clamps.
• Branch length should be minimum 50mm.
• Minimum distance between clip and nearest branching point should be 25mm.
• Minimum distance between two breakouts should be 50mm.
• Limit the no. of branches from single branch point to 4.
• Ensure that harness protection is provided according to surrounding temperature, manufacturabilty and expected reliability.
• The min. bend radius is to be 1.4.
• Consider min 5% slack in the wiring harness if needed.

Procedure :

Create context assembly product file:

Image : Context assembly product file

Create context assembly as shown in the image above. The context assembly will contain 3D CAD data for the engine and engine harness geometrical bundle assembly. Any sheet metal component such as L-clip required will be added into the context assembly.

Define the connectors electrically

(a).Connectors:

Before adding connectors into the geometrical bundle define all the required connectors electrically.

Part No: C-1563689-1

No of terminals: 4

No of Quantity : 20

Part No : C-776438-4

No of terminals: 12

No of Quantity : 1

(b).Mounting Equipment:

Part No: C-1924487-2

No of Quantity : 1

3. P Clamp:

Inserting connectors into geometrical bundle and positioning them.

The connectors are inserted into the geometrical bundle and positioned onto the fuel injectors, camshaft sensors, vehicle speed sensor, neutral position sensor and engine coolant sensor as shown in the images below.

Connectors connected to fuel injectors

Connectors connected to camshaft sensors, vehicle speed sensor, engine coolant sensor and neutral position sensor.

Defining P clamp as support

Use support command again and select first plane definition as exit point and exit plane, this is done to obtain wiring entry from either sides of P-clamps.

P-Clamps are mounted on the existing bolts and screws to provide positive clamping and ensure proper clearance management for the wiring harness routing.

Adding plastic guiding channels

The given V-16 engine has 8 injectors both on the left and right side of the engine which are close to one another, hence using plastic guiding channels is the best option for easy and proper routing of the wiring harness and maintain clearance requirement of the wires from the high temperature parts of the engines.

Before adding guiding channels into the geometrical bundle assembly it is necessary to define electrical properties to it, which is done by following steps.

First create geometrical parameters such as bundle entry points, and external reference line in the part design workbench to route the wiring harness into the guiding channel as shown below.

Go to electrical part design and define the part as equipment using equipment command and define bundle connection points using bundle connection point command towards the entry points of the guiding channel as shown in the image below.

Now insert the guiding channel into the geometrical bundle and position it accordingly as required, both on the left and right side of the engine as shown in the image below.

Discuss with engine design team to provide additional tappings wherever required to mount the guiding channels with bolts and screws.

Now as all the components are inserted and positioned into the geometrical bundle, the assembly is ready to route the harness.

HARNESS ROUTING:

Applying protective covering.

CONNECTIVITY CHECKUP:

Creating flatten pattern of wiring harness bundle.

To make a flattened view of any wiring harness we should be working in the Electrical Harness Flattening workbench of CATIA V5.We should also make sure that the flattening file is saved in the same folder where we have all the parts of the harness assembly.

Defining the Harness Flattening parameter.Make sure to use the "single line" for the Bundle segment and "Double line" for protrctive covering.

We have extracted the bundle assembly into Engine Harness Flattening Product file and then flattened the file along face of interconnection connector as shown in above figure.

At this stage, for clarity, we have been hidden the flattening diagram of the plastic guiding channels from the drawing view.

Create drawing of the flattened harness

i) Go to new and select drawing to create a new drawing file.

ii) Select front view command, go to the flattened harness window and select a suitable face to create drafting of the harness. The wiring harness appears as shown below.

iii) To make the bundle segments visible right click on the drawing sheet and go to properties, in the view tab, highlight '3D wireframe' and 'is always visible' in the dress up settings.

The bundle segment appears in the wiring harness as shown below.

Conclusion: Thus the engine harness routing is completed and the flatten view drawing is created.