Challenge

Project 1 - Wiring harness routing on given Engine

AAnjith Vs27 Jun 2023

AIM

To route the Wiring harness on Given Engine and Prepare flatten view drawing in CATIA V5.

THEORY

Wiring Harness

An automotive wiring harness is a network of interconnected wires, cables, and connectors that are used to transmit electrical signals and power throughout a vehicle. It serves as the central nervous system of a car, connecting various electrical components and systems to enable their proper functioning.

The wiring harness is designed to organize and protect the electrical wiring in a vehicle, ensuring reliable and efficient transmission of signals and power. It consists of multiple individual wires, each with a specific purpose, such as supplying power to different components, transmitting data signals, or controlling various functions.

Wiring Harness Terms

Wiring harness is the assembly of different systems, sub-systems in the vehicle. It won’t have any function; it depends on its system and sub-systems. It used to pass the signals between components.

Wires and Cables: The wiring harness is composed of numerous wires and cables of different gauges and colors. These wires are made of copper or aluminum, which are excellent conductors of electricity. The gauges and colors of the wires are standardized and follow specific industry conventions.
Connectors: Connectors are used to join different sections of the wiring harness together or to connect it to electrical components. They provide secure and reliable connections, enabling easy installation, maintenance, and repairs. Connectors can be of various types, such as plugs, sockets, terminals, or splices, and they often have unique shapes or keying to prevent incorrect connections.
Branches and Terminations: Wiring harnesses are designed to accommodate the complex electrical layout of a vehicle. They have branches and terminations that split off from the main harness to reach various components, such as the engine, lights, dashboard, entertainment system, or sensors. These branches ensure that the wiring reaches the required destination without excessive length or unnecessary complexity.
Protection and Insulation: Automotive wiring harnesses are typically protected by non-conductive materials, such as plastic or rubber sleeves, to prevent wires from chafing, short-circuiting, or getting damaged due to heat, moisture, or vibrations. Some areas of the harness may have additional protection, such as conduit or loom, to enhance durability and safeguard against environmental conditions.
Labeling and Identification: To simplify installation, troubleshooting, and maintenance, wiring harnesses often feature labeling or color-coding. Wires are marked with specific identification codes or labels that correspond to the vehicle's electrical diagrams or manuals. This makes it easier to identify individual wires and their intended connections.
Clips and clamps: Wide variety of clips and clamps are available to mount the wiring harness.
Fuse and relay box: are plastic moulded parts used to package Fuses and relays in systematic manner. It also protects them for any damage (Physical and Environmental).
Retention device: are plastic moulded parts to mount connectors and other harness components. (Connector mounts, secondary locks, connector back shell etc). Primary locking is provided by the terminal itself; secondary locks are not mandatory but there are used to ensure that there is no damage. Back shells are the packaging devices which are used at the end of the connectors. It guides the wire to the connector in a constrain packaging area or to provide the better appearance at the end of the connector.
Guiding channels: are plastic moulded or metal parts designed to guide harness bundle in given geometric area to secure and protect the harness.
Electronic components: Diodes, terminating resistors, Flasher, Timer circuits are sometimes part of harness supply.

Wiring Harness Routing

Wiring harness routing refers to the process of arranging and securing electrical wiring harnesses within a vehicle or any other machinery. A wiring harness is a collection of wires, connectors, and other components that are bundled together to provide a centralized electrical connection and ensure proper functioning of various electrical systems.

During the manufacturing or assembly process, wiring harnesses are routed and positioned within the vehicle or machinery to optimize their functionality, ensure safety, and minimize the risk of damage or interference. This involves determining the most suitable path for the harnesses to follow, taking into account factors such as electrical requirements, space constraints, heat management, and protection against vibration or abrasion.

Wiring harness routing typically involves the following steps:

Design and planning: Engineers or designers analyze the electrical requirements of the vehicle or machinery and create a wiring diagram that outlines the connections and components of the wiring harness. They also consider the physical layout of the vehicle or machinery to determine the most efficient routing paths.
Path selection: Based on the design and available space, engineers select the optimal path for routing the wiring harness. They consider factors such as the proximity to electrical components, avoidance of heat sources or moving parts, and accessibility for maintenance or repairs.
Mounting and securing: Once the routing path is determined, the wiring harness is mounted and secured using various methods such as clips, brackets, or adhesive tapes. This ensures that the harness remains in place and is protected from damage due to vibration or contact with other components.
Testing and validation: After the wiring harness is routed and secured, it undergoes testing to verify proper electrical connections and functionality. This may involve continuity tests, insulation checks, and other electrical tests to ensure that the harness is correctly installed and operating as intended.

Design Criteria for Wiring harness

Wiring harness should be routed in following way that :

it is easy to assemble on vehicle.
It is easy to access in case of service or failure analysis.
It should be secured properly so that it should not get damaged by surrounding component intraction.
It should be kept away from heat zones like engine exhaust,mufflers,turbo chargers.
It should be kept away from areas of direct water splashes.
It should be kept away from sharp environment like sheetmetal bracket edges, corners, panel edges etc.
It has to ensure human or machine intraction will not cause any dameges to harness.
It should be kept away from driver or passanger reach zone.
It should be kept away from High pressure fluid lines.
Dynamic conditions of the vehicle should not damage the wiring harness.
Keep harness away from tyre envlope.
The harness should not be visible or exposed inside the vehicle.

Packaging Rules

Wiring harness routing shall provide ease in manufacturing, accessibility, easy removal, and easy maintenance of attached equipment and wiring harnesses.
Routing through small structural holes and openings shall be avoided, minimizing chaffing and handling of the wiring harness during installation.
Avoid the harness routing and clipping in the Blind zone of the Operator during harness assembly or in service.
Routing shall offer protection against possible damage through common misuses such as being handheld and temporary support for test equipment.
Provide additional slack to the harness according to the surroundings and harness bending requirements.
Ensure the routing meets the clearance requirements with different surrounding parts.
Routing shall provide enough slack for each branch to provide additional stress on wire and terminal crimping joint but also ensure extra slage creates wiring harness fouling.
Avoid routing over the bolts, near the bolted joints. It may damage the harness or puncture the harness. Keep harnesses away from panel mounting screws.
Avoid harness routing near sharp edges, if not possible provide protection to the harness.
The maximum distance between two clips on a straight branch is 200mm.
Provide Clips and clamps if the harness is going to bend at multiple locations.
The use of too many sheet-metal brackets should be avoided.
The branch length should be more than 50 mm.
The minimium distance between the clip and the branching point is to be 25 mm.
The minimium between two branch breakouts should be 50 mm.
Use of rubber grommets is recommended if the harness is passing through sheet metal panels.
Always keep the harness connector at higher than the harness routing and branching points, to make sure water does not enter due to gravity.

Assumptions :

Provide clips/clamps as per requirement.
Make sure that there is no falling case while designing the wire harness. Additional clips/clamps may be used to avoid falling cases.
Give additional slack if needed. 5-10% slack is sufficient.
Avoid routing over the bolt and bolted joints to avoid harness puncture.
Avoid routing on sharp edges or else provide protection over the harness.
Follow the clearance distance and keep away the harness from heat generation components.
Protection should be provided as needed according to the surrounding temperature.
Avoid direct support for harnesses on fuel lines routed in the engine.
Use plastic guiding channels if needed.
The branch length should be greater than 50mm.
The minimum distance between two branch points should be at least 50mm.
The minimum distance between the clip and the branch point should be at least 25mm.
Avoid too many sheet metal brackets on the engine. Try to use available threaded bosses on the engine or demand for it.
The wiring harness should be easy to assemble and easy to access.
While using dummy connectors, ensure that whatever positions you are defining is practical. Bundle diameters and other placements can be defined properly for the wire harness routing.
If the packaging area is too tight and there are many packaging constraints then we can think of creating a harness channel that can be used to route and protect the wire harness effectively.

Clearance Managment

PROCEDURE

Step 1 : Defining the connectors electrically and clamps and clips.

Defining 12 pole connector :

Defining Mounting Clip:

Opened Electrical assembly design and imported connector and mountin clip to connect eachother :

Defining 4 pole connector :

Defining 2 pole connector :

Connector - C-282080-1 :

Defining Channel :

First Geometrical parameteres were defined, then the part is defined as equipment

Now the bundle entry points were added to the part

Defining Fir tree clip

Step 2 : Creating Context Assembly

A Context Assembly for Engine Harness is created which will work as the main assembly.

A Context Assembly will contain Engine Assembly data for Engine and Engine Harness Geometrical Bundle Assembly.

Step 3 : Add Engine assembly to the Context assembly

Step 4 : Add New product int the Context assembly and rename it as 'Engine Harness Geometrical Bundle' and save it in the same folder.

Step 5 : Inserting the connectors and position them accordingly.

Here we have to place connectors to fuel injector sensors and cam-shaft sensors.

Total 20 connectors are required to added in the Engine Harness Geometrical Bundle.

Inserting 4 pole connectors for the injectors:

Connectors at front of engine:

2 pole connector at front of the engine

RPM sensor connector :

Coolant temperature sensor :

Inserting L clip for mounting interconnection connector.

Inserted 12 pole interconnection connector :

Inserting Channel :

Inserting P clamp and Fir tree clip for support:

Two type of fir tree clip is used in the design one id 15 mm and other is 10 mm clip according to the bundle size.

Step 6: Wiring harness routing

After inserting and placing all the required connectors, clips and channels required the next step is wiring harness routing.
Switch to Electrical harness assembly workbench
Define the assembly as electrical assembly and start routing

The routing starts from the interconnection connector:

Injector wiring routing with packing:

The main harness is given diamater of 15 mm,whereas the 4 pole connector wirings were given diameter of 10 mm and other connectors wire diameter is taken as 8 mm.