Discussion on Modular Design of Automobile Harness

KSK is the abbreviation of German Kundenspezifischer Kabelbaum, which means customer-made Wiring Harness. Its concept and principle were put forward and put on the market by German DeKosmir Group in 1990. This idea that wire harnesses with different configurations can be delivered to customers in time was favored by BMW, Mercedes-Benz and Audi at that time, and it can be well matched with the new Just-in-time manufacturing mode in automobile production. Because KSK can meet the special requirements of vehicles with different configurations including different parts, this idea subverts the traditional design mode of automotive wiring loom at that time, and pushes the personalized customization of automobiles to the stage of history. It is precisely because of this innovation that DeCosmir has established its position as a global leader in automotive wiring harness industry.

1 The Necessity of Modularization

As early as the 2011 Hannover Industrial Fair in Germany, a research group composed of Bosch and Leo-poldina has put forward the concept of Industry 4.0, which is defined as the traditional process and service that connects the digital Internet world with the production economy.

Industry 4.0 aims to integrate the current Internet and Internet of Things technologies, optimize the production processes in traditional industries, and build an intelligent factory. Its ultimate goal is to realize mass customization, quickly respond to customer needs, meet different individual needs of different customers, and take into account low-cost and high-efficiency mass production.

As a highly automated automobile industry, it will surely become the pioneer of Industry 4.0. However, how to meet the increasing customer customization needs has become an important issue in the process of realizing Industry 4.0. When the car is highly customized, most of the configurations in the car can be selected according to the needs of customers. If these possibilities are arranged and combined, there will be thousands of different results. As a separate individual part of the automobile, the wiring harness connects all the electric appliances in the automobile, and it needs to meet different functional configurations, so it has high complexity. At this time, we must simplify the complexity. At this time, the concept of modular production came into being. The basic idea is: during the design, all the functions in the car that customers can choose are divided into different modules, and then the wiring harness is produced by pulling the modules in the actual production, and finally it is matched with the customized production of the whole car. Every part of automotive wiring harness should have its module attribute. The application of modular production can make the production of Wire Harness more diversified, realize one car and one line, and meet the individual needs of customers.

2 How to Achieve Modularity

2.1 Module Division

At the beginning of wiring harness design, the modules must be clearly defined, and then each part is divided into different modules. Each module must contain components of wiring harness such as connectors, wires, terminals, waterproof plugs, fasteners, fuses and relays. When defining modules, all the functions of electrical appliances should be divided into two types: basic modules and functional modules.

2.1.1 Basic Modules

The foundation of the module is defined as Module Basic, which is unique. All parts in the module are used for the required functions suitable for all vehicle configurations, and these functions do not contain multiple configurations. Therefore, there should be only one basic module in the wiring harness drawing, and all models share the same basic module. The basic module generally includes general functions such as BCM, fuse box in inner cabin and diagnosis.

2.1.2 Functional Modules

A module contains functions that have multiple choices or may have multiple choices in the future. With the rapid growth of the number of automotive electrical appliances, a huge group of functional modules will be generated. In order to manage these modules more easily, functional modules can be divided into three levels: module group, functional modules and branch modules.

1) module groups are divided into module groups, such as Module A, Module B and Module C, according to their functions, such as ABS module, headlamp module and radio module.

2) Functional modules are subdivided into modules such as Module AA, Module AB and Module AC according to specific functional differences. For example, under the headlamp module, they can be divided into halogen headlamp module, xenon headlamp module and LED headlamp module.

3) The same function of the branch module is matched with different sheet metal, resulting in different branch lengths, so it is necessary to additionally derive modules Module AAA, Module AAB, etc. In actual production, branches with different lengths can be selected according to the needs of sheet metal.

2.2 Definition of Wire Module

As an important part of the wire harness, in the process of modularization, a clear module definition is required. However, the loop always connects the devices at both ends, which has its particularity. Whether a certain loop will be placed in the module of equipment side A or the module of equipment side B is the place to be considered.

Generally, the following principles are followed to define modules for wires:

1) Two of the basic modules are connected by electrical appliances, and this circuit belongs to the basic module.

2) The electrical appliance of the basic module is directly connected with the electrical appliance of the functional module, and this wire belongs to the functional module.

3) If the electrical appliances of two different functional modules are connected, it is necessary to judge their affiliation and then classify the circuits.

4) There is a welding point between the basic module electrical appliances and the functional module electrical appliances. The welding point can be regarded as an electrical appliance and its module attribute can be judged. Then judge the module attribute of the connected circuit according to the first three items.

5) If only one end of a certain circuit is connected with electrical appliances and the other end is grounded, the circuit is defined according to its electrical appliances.

2.3 Complexity Reduction

How to divide the basic modules and functional modules has been introduced. However, if each optional or potentially optional electrical appliance in the automobile is taken as a functional module alone, a highly complex module group will be generated, which is obviously inappropriate for the current technology, because it will greatly increase the management cost. For example, it is a waste of module definition to divide four window shutters into four different functional modules. Therefore, it is necessary to merge modules, optimize module management and reduce management costs on the premise of ensuring module flexibility.

1) The same type of electrical appliances have the same type, and ensure that they will be assembled at the same time. For example, four seats in the front and rear rows have heating function, and there can be four modules in theory. However, in fact, no single seat will be selected for heating, but the front or front and rear rows will be heated. Therefore, the front seat heating can be combined into one module, and so can the rear seat.

2) Functions coexist with different types of electrical appliances, but they are connected to each other and serve the same function. For example, a car phone includes a microphone, buttons, a radio, and an antenna. If the modules are divided separately, four modules will be established. In practical application, these four electrical appliances serve the function of the car phone at the same time, and only need to be divided into the car phone module.

3) Configuration and selection. At present, users mainly choose the type of car, and configure the vehicle according to the selected comfort or flagship type or optional package. For example, high-profile models are equipped with rearview mirror electric folding and induction wiper. Although these two functions are different in type and function, they can be selected at the same time, so the two electrical appliances can also be combined in the same module. This can reduce the current module management cost, and then disassemble it when necessary.

4) Redundant cabling includes some branches in some specific configurations, whether customers have ordered them or not. For example, whether the customer chooses the front fog lamp or not, this branch is included in the harness parts. This method is only applicable when the reduced management cost is greater than the actual material increase cost.

3 Modular Solutions for Different Software

In order to realize the modular design in the wiring harness, the electronic system design software (ESD) developed by Mentor Graphics simplifies the definition of module codes in the design stage, and speeds up the material distribution of functional modules in the engineering stage and production modules in the manufacturing stage. At the beginning of the design, the functions supported by each wire and the relationship among them are defined. When designing, wires are synthesized first, and then modules are automatically assigned to the wires, and wires with the same expression are classified into the same module. For wires without expression, it means that the wires are all selected for all models, and this kind of wires are assigned to the core module code. In the whole process, the software can automatically complete the work related to modularization and provide reliable configuration.

In view of the highly complex wire harness design, Aucotec Company has launched the Engineering Base software (EB for short). EB central data module covers the whole process from design to production. The software adopts 150% modular design method, supports variable design of connectors, modular design of wires and variable design, and controls the production configuration of actual vehicle models by combining variables with modules. In addition, EB can also face the production, configure the actual information of each individual wire harness, and automatically analyze and redistribute the modules, and export the manufacturing special modules, which saves a lot of work in the production process and improves the production efficiency.

To meet the design requirements of KSK, Zuken also developed E3.Harness Analyzer software. This software can combine KBL (Harness Information List) and SVG (Scalable Vector Diagram) data into HCV database, support harness drawings with module information, and display relevant information of modules and module groups according to STEP AP212 KBL data structure. In the software, users can select and configure the modules and store them in the HCV database.

4 Modularization of Automobile Parts

Nowadays, KSK's wire harness production mode has been gradually popularized in OEMs and suppliers, but its initial stage is mainly aimed at the customization of wires and related accessories. In the future, we can continue to expand this concept and extend it to every part of the car that customers can choose.

At present, the next stage that is more likely to be realized is the modularization of fuse box. The fuse and the base in the fuse box can be divided into small fuse groups, which can be divided into basic and functional modules according to their functions. These fuse groups are equipped with small fuse boxes, and the fuse boxes can be spliced and disassembled from each other. In actual production, modules are selected according to the vehicle configuration, and then different modules are spliced and assembled. The modules of these fuse boxes have mechanical and electrical connections at the same time, which can be superimposed and used as required like imposition, and continuously expanded. This not only increases the versatility and stability of the fuse box, but also reduces the material, installation space, quality and cost. In this way, from the perspective of parts, it meets the needs of customers' customization, and will be extended to more functional parts in the future.

5 Concluding Remarks

KSK is the initial embodiment of customer customization in industrial production. Some large OEMs in Germany have begun to adopt modular production. After determining the combination of engine and transmission, customers can freely combine and match the interior and exterior decoration and electronic functions of automobiles. However, such production and development methods have not been popularized in the Chinese market. At present, only Volkswagen, Audi, Skoda, BMW and Mercedes-Benz have adopted modular production methods. Among them, only some models of Volkswagen and Skoda have completed the development of modular wiring harnesses in China, and the rest are produced according to drawings. There is still great potential in the direction of modular production in China.

With the continuous improvement of users' personalized needs, KSK's production mode will become the mainstream, and it will continue to develop into various fields in the future, so as to achieve high-complexity production in mass production. This requires enterprises like Kable-X to make all-round reforms from R&D to production, from logistics to management, which is both an opportunity and a challenge. Industry 4.0 will lead the 4th industrial revolution, and its ultimate goal is to meet customer needs and make industrial products more personalized and humanized. I hope that in the near future, everyone can enjoy customized products that fully meet their own needs.