Automotive Circuit Harness Design Method

Utformingen av Automotive Circuit Harnesses trenger å vurdere sikkerhet omfattende, Pålitelighet, Elektromagnetisk kompatibilitet og vedlikeholdskonferanse. Følgende er kjernedesignmetodene og prinsippene:
1. Designprinsipper og spesifikasjoner
Sikkerhet først
Høyspentledninger (som nye energikjøretøyer) må ta i bruk en tosporsdesign for å unngå kroppen som et jordingspunkt, og følg strengt kravene til høyspenningsmotstand og beskyttelsesnivå.
Selene må unngå kollisjonsdeformasjonsområder (som anti-kollisjonsbjelker og innvendige dører) for å forhindre isolasjonsskader og lekkasje.
Ledningene må pakkes pent sammen, festet og klemt, og beskyttet når du passerer gjennom hull, og forskyvningen under nødbremsing bør reserveres.

‌Modulært og segmentert design‌
Del selemodulene (som motorsele, instrument sele, dørsele, etc.) i henhold til funksjonsområder for å redusere lengden på hovedselen, redusere kostnader og lette demontering og montering.
Segmented connectors should be arranged in a hidden and easy-to-maintain location to avoid the risk of bumps.

‌Electromagnetic compatibility (EMC)‌
High-voltage harnesses should be routed under the chassis as much as possible to reduce electromagnetic interference. For sensitive signal lines (som CAN-buss), twisted pair or shielded wire design is used to enhance anti-interference ability.

Detaljert forklaring av bilkretsdiagramgjenkjenning og analyse

2. Arrangement method
‌Fixation and spacing requirements‌
The spacing between adjacent fixing points of high-voltage harnesses is determined according to the cross-sectional area:
When the cross-sectional area is greater than 16 mm², the spacing is ≤300 mm;
When the cross-sectional area is ≤16 mm², the spacing is ≤200 mm‌.
The gap between the harness and the stationary parts is ≥10 mm, avoiding contact with sharp edges, høye temperaturer, og bevegelige deler. Om nødvendig, add a heat shield or corrugated tube for protection‌.

‌Wiring path optimization‌
High-voltage harnesses should avoid crossing or winding, and the positive and negative wires should be routed in the same path. De tilhørende selene (such as the three-phase wires of the motor) should be arranged symmetrically‌.
When the cockpit and the front cabin harnesses are connected, they must be passed through the body sheet metal holes and sealed to prevent water and dust leakage‌.

‌Three-dimensional layout specifications‌
Combine the body sheet metal structure to plan the direction of the wiring harness to ensure the convenience of assembly and maintenance. Kontakten er anordnet i en posisjon som er lett å betjene for å unngå vanskeligheten med å koble til og fra med én hånd‌8.

Iii. ‌Spesialdesign av høyspent ledningsnett
‌Dobbeltsporssystem og koblingsvalg‌
Høyspentkretsen vedtar strengt en tosporsdesign. Koblingen må ha sløyfeforrigling, høyt beskyttelsesnivå (som IP67) og skjermingsfunksjon, og modne leverandører foretrekkes‌.

Høyspent ledningsnett som drivsystemer og ladestasjoner må arrangeres uavhengig og jevnt symmetrisk‌.

‌ Protective tiltak‌
Motorrommets ledningsnett må være motstandsdyktig mot høy temperatur og vibrasjoner, og faste punkter må settes hver 200 mm, med en avstand på ≥100 mm fra varmekilden‌.

Use plastic protective covers when passing the door wiring harness through holes, and arrange them on the dry side of the door to reduce the risk of water leakage‌.

IV. ‌Verifisering og optimalisering
Gjennomgang av ordningen
The design stage needs to pass multi-departmental reviews (design, behandle, kvalitet, produksjon) for å sikre gjennomførbarheten av ordningen.

‌Prøveproduksjon og testing
Verify the two-dimensional drawings through three-dimensional wiring diagrams and schematics, og opptre funksjonell, durability and environmental adaptability tests after trial production‌.
The above design methods need to be comprehensively optimized in combination with the vehicle electrical load, driftsforhold (such as continuous/short-time/random working system) og miljøfaktorer (temperatur, vibrasjon).

Forskning og anvendelse av designmetode for ledningsnett for biler

Som en viktig andel av ledningsnettkostnaden, ledningsnettet i bilen har en betydelig innvirkning på optimaliseringen av kostnadene for ledningsnettet. Det er også direkte relatert til sikkerheten og påliteligheten til kjøretøyets elektriske apparater. Basert på arbeidspraksis, denne artikkelen oppsummerer mange betraktninger for sløyfedesign både når det gjelder kostnad og ytelse, og foreslår spesifikke kontrollstrategier og implementeringstilnærminger, gir teknisk støtte for effektiv og nøyaktig design av ledningssløyfe. Det har sterk veiledende betydning for ledningsnettdesignere.

1 Introduksjon
Ledningsprodukter fungerer som tilkoblingsbærer for elektriske funksjoner i biler og realiserer kretsforbindelsen mellom forskjellige elektriske komponenter. Startpunktet og sluttpunktet for hver kretsforbindelse utgjør sløyfen i ledningsnettproduktet. Det kan sies at ledningsnettkretsen er kjernen i ledningsnettproduktet. Kvaliteten på kretsdesignet til ledningsnettproduktet bestemmer direkte sikkerheten og påliteligheten til kjøretøyets ledningsnett. Ettersom graden av elektrifisering av kjøretøy øker, dataene til elektriske komponenter øker, signalsamspillet mellom elektriske apparater blir mer og mer intimt, og antallet ledningsnettsløyfer for biler øker også kraftig. The wiring harness circuit data of general vehicle models has reached nearly 1,000 (Figur 1).
How to optimize and coordinate such a large number of circuits is a difficult problem faced by automotive wiring harness design.
The existing technical information on automotive wire harness design mainly provides design guidance for wire harness design in the selection of wire harness materials and manufacturing and processing links, but lacks systematic analysis of the planning and design concepts of wire harness circuits. This article explains the relevant key points of wire harness loop design from two aspects: cost and performance, and provides specific control paths. It has a certain guiding role in the design of wiring harness circuits.

2 Cost-based loop design method
The wiring harness loop accounts for about 90% of the wiring harness material cost, including wires and connectors. To control the cost of wire harness design, we must start from the optimization of wire harness loop design.
Regarding the use of wires, how to achieve the loop connection function with the minimum wire length is the first issue to be considered in loop design. This involves two aspects of design elements: the placement location of electrical components and the selection of wiring harness layout paths. These two factors are independent but interrelated and have a significant impact on the use of wire length.
Først, it is necessary to determine the connection method of the circuit based on the principle of components, and then determine the preliminary position of the layout of each component in the vehicle environment. The selection of the wiring harness layout path is based on the layout position of the components, using the shortest wire harness length to cover as much of the component layout area as possible. This is also the prototype of the vehicle electrical topology.

After completing the vehicle topology construction, it needs to be designed and verified. By calculating the specific wire usage, we can determine whether the layout position of components and the wiring harness layout path are reasonable (there are currently a large number of software on the market that can realize this function). The specific method is to compare by adjusting the parts one by one. Som vist i figur 2 og figur 3, the designs of different BCM layout positions are compared to check the length and amount of wires used in the vehicle, and then determine which position of BCM layout is better.
I denne prosessen, mutual influence often occurs: the adjustment of the layout of component A will affect the selection of the location of component B. Derfor, after determining the impact of each component and wiring harness path on the length of the wire one by one, the one that has a greater impact on the length of the wire will be selected as the first-round preferred solution. På dette grunnlaget, the topology is rebuilt and other secondary solutions are compared and analyzed again. This achieves a topology design platform with the smallest wire length.
A perfect topology can ensure the minimum amount of wire usage. Samtidig, regarding the use of wires, the traditional design concept has clear requirements for the selection of wires. In order to avoid confusion in terminal plugging, more wire colors are often used to distinguish them. Imidlertid, as the manufacturing level and inspection methods continue to improve, the wire colors of the wires can actually be appropriately designed and adjusted to realize the loop function with the minimum number of wire types, which is also a method to reduce the loop design cost from a design perspective.
For connectors, how to minimize the use of connectors and reduce transfer loops is what needs to be focused on in loop design. Her, the wiring harness design engineer needs to transform into a system design engineer, and the design work of reducing the use of connectors and transfer loops needs to be moved to the design and planning of electrical components. There are two main aspects to consider:
On the one hand, functional circuits of electrical components can be distinguished according to vehicle model configurations. For eksempel, for airbag controllers, basic functional circuits can be designed in the same connector, while advanced or extended functions can be arranged in another connector. På denne måten, only one connector can be used on low-end models, and the electrical circuit function can also be realized.
On the other hand, it can also be planned according to the connection area of the circuit, such as the airbag controller. Some designers will consider designing the functions of the chassis in the same connector and the functions of the instrument panel in another connector. This kind of planning can reduce the mutual transfer of circuits in various regions. This area-based functional loop design is particularly effective for electrical components with a large number of connected pins (such as BCM controllers).

3 – Circuit design method based on wire harness performance
The wiring harness loop is the core of realizing circuit connection. The safety and reliability of its circuit connections are requirements that must be met. The wires and connectors in the circuit design must comply with the requirements of the load and environment. These contents have been described in detail in other design materials. This article only explains how to ensure the design of loop performance from the perspective of loop path selection.
Først, the circuit design must avoid undetectable failure modes. Som vist i figur 4, the rear part of the fuse is connected in parallel with the relay coil end and contact end. This kind of design is very common in vehicle circuit design. This design is obviously reasonable when the relay coil end and contact end terminals are different. Imidlertid, when the relay coil end and contact end terminals are the same, current electrical inspection equipment cannot identify such a failure mode when the terminals are inserted into the relay holes in the wrong position.
Derfor, this loop design method cannot be used in some cases. Selvfølgelig, different design engineers face different design environments and manufacturing environments, and the specific failure modes will also be different, but the avoidance of failure modes in circuit design is the first thing to consider.
On the other hand, the current level of automotive electronics has improved significantly. As an electronic carrier, the electromagnetic environment faced by automobiles is also more complex, and how to reduce electromagnetic interference in wire harness circuit design is an inevitable topic. Wire coupling interference (Figur 5), power supply interference, ground interference, radiation interference, osv. will all have adverse effects on the normal operation of electrical devices. The circuits in the wire harness are bundled together, and the wire coupling interference generated between the wire harness loops and between the wire harness and the metal conductor is particularly prominent in the wire harness.
To reduce wire coupling interference in loop design, we must first distinguish between interference loops and sensitive loops. To put it simply, inductive load circuits such as ignition coils, høyttalere, motorer, osv. are interference circuits, while circuits such as imaging, radar probes, low-power LED lights, and various sensors are sensitive circuits. Interference loops and sensitive loops need to be arranged separately during the design process. Tests have shown that increasing the distance between wires can reduce high-frequency interference (Figur 6). If the distinction cannot be made, functional testing needs to be carried out by injecting interference into the wires to determine the correctness of the circuit design.
Samtidig, in order to reduce the influence of wire harness radiation and coupling, the circuit loop area and wire harness length should be reduced as much as possible. In the design of the entire vehicle, it is necessary to minimize the loop area of the wiring harness, spesielt kraftledningene og jordledningene. Det kreves at ledningsnettene i sløyfen skal føres parallelt så mye som mulig og festes så nært metalllegemet som mulig for å redusere sløyfearealet, og avstanden mellom ledningene bør ikke overstige 50 cm.
I tillegg til vurderingen av utformingen av interferensløkker og sensitive løkker, antiinterferenskomponentene tvunnet par og skjermede ledninger som brukes på ledningsnettet, må også tas hensyn til i sløyfedesignen for å oppnå skjermingsforventninger. De to ledningene til det tvunnede paret skal ha samme diameter og lengde, og vridningsavstanden skal være 10~20mm. Den spesifikke vrilengden er gjenstand for eksperimentell testing. Skjoldjordingsterminalen skal koble skjermen 360° til skjermskallet i begge ender. Skjermingslaget og skjermingsskallet danner et komplett skjold på signallinjen. Hvis skallet til komponenten som er koblet til den skjermede kabelen ikke er av metallstruktur, ledende metallklemmer kan brukes til å presse skjermingslaget på metallplaten som er pålitelig koblet til bilens karosseri. Skjermingseffektiviteten skal nå 60dB.

4 Konklusjon
Denne artikkelen analyserer designmetoden for ledningsnett for biler fra to aspekter: cost and performance, og forklarer anvendelsen av spesifikke metoder basert på arbeidspraksis. Nøkkelpunktene i ledningssløyfedesign trekkes ut, som har veiledende betydning for ledningsnettdesignere i sløyfedesignprosessen.