General design requirements for high voltage wire harness protection

2022-02-01
General design requirements for high voltage wire harness protection
There are a variety of fixed ways for high voltage wiring harness. Different fixed parts can be reasonably selected according to the situation of different areas of the vehicle. The following rules are generally followed in the layout:  

(1) Insulation performance  
 
Any fixed/protective parts should be insulated and adequately protected against corrosion and rust, thereby affecting the reliability of their fixation.  
 
(2) Fixed parts layout distance  
 
To minimize the impact of the swing of the high-voltage cable harness on the connector or crimping terminal, secure the high-voltage cable harness at the outlet of the connector tail less than 120mm for the first time.  

If the high-voltage cable harness cannot be laid in the cable trough, fix it at intervals of 150mm to 250mm.  
 
When the hV wire harness is laid along a straight line, the gap between two adjacent fixed points should meet the following requirements:  
 
(1) The cross-sectional area of the high voltage wiring harness is greater than 16mm², and the gap between adjacent fixed points is less than or equal to 300mm;  

 
(2) The cross-sectional area of the high-voltage wire harness is ≤16mm², and the gap between adjacent fixed points is ≤200mm.  

When high voltage wire influenced by environment, need to install the active parts (such as belt, fan, transmission shaft, etc.), and must be fixed in the state of bending, requires the reasonable distribution of load, the general advice can increase long-term bear big force auxiliary fixing parts used in fixed, the adjacent two fixed spacing is 300 mm or less, and fixed in the corner of two endpoints,  The distance between the fixed point and the connector should be less than or equal to 150mm. Only in this way, the weight and vibration load of the wire harness can be borne without wear of the wire harness or interference of the nearby moving parts.  

[High voltage wire harness fixing scheme]  
High voltage wiring harnesses are usually arranged and fixed along the sheet metal of the car body. During the operation of the vehicle, vibration cannot be avoided. Therefore, all high voltage wiring harnesses need to be treated with anti-vibration and anti-wear.
Vibration resistance is generally achieved by using fasteners on high voltage wiring harnesses.  All kinds of fixers minimize the relative movement between the hV harness and the car body, and also fix, protect and guide the hV harness.   
Due to the high strength of the high voltage wire harness, different processing is needed according to the different length of the wire harness. It is generally required to fix the wire harness with smooth support without burr, wire groove, wire clip, tie belt, etc.  When using cable ties to fix the cable ties, you should fully consider the method of fixing the cable ties, so as to select appropriate cable ties to fix the cable ties and avoid the risk of fixing failure.   
Wear protection is generally achieved by using bellows/plastic wear resistant tubes and other components outside the high-voltage wire harness. In particular, there are metal components near the installation and layout area of the high-voltage wire harness, which may have burr and flange structures. Therefore, protective components should be used to protect the high-voltage wire harness to reduce the possibility of wear and tear.  
 
The distance between the wire harness fixed protectors shall not be greater than 400mm.  And the high voltage wire harness shall not cause interference to the moving parts, and the distance between the two shall not be less than 50mm.  The power battery of pure electric vehicle is arranged in the rear bottom plate of the vehicle, and the high-voltage wire harness led from the front end of the battery passes under the bottom plate of the vehicle, which is close to the ground. It is necessary to increase the protection of bellows outside the cable to prevent the high-voltage wire harness from the stone splashing on the road in the process of driving.  For some positions, bellows cannot be used to protect the wire harness due to space requirements. Plastic grooves can be added outside the high-pressure wire harness to protect the wire harness.  
 
At present, the common fastening methods of high voltage wiring harnesses include the following schemes:  

(1) Round hole fixation, usually using integrated fixed tie with wedge fixed head, integrated fixed tie with cedar shaped fixed head.  
 
(2) Welding stud fixing, usually use the integrated welding stud fixing tape, with welding stud fixing piece isolated double chuck tie tape.  (3) Pipe type fixation, using cable ties and pipe clamp buckle assembly hoop outside the high pressure wire harness.  
3) sheath protection  
 
The sheath can be used for the parts that are easy to be damaged and easily affected by impact, which can effectively prevent the wear of wire harness. It is characterized by high temperature resistance, impact proof, cutting proof, light weight and easy installation. Compared with bellows, its wear resistance is higher, the outer diameter is smaller, and it will be improved as it is.  
 
(4) The edge of the plate is fixed. For the metal plate with an edge less than 3mm, the edge buckle is used to fix it.  
 
(5) Wire bracket is fixed. For high-voltage wire with wire diameter ≥35mm², the high-voltage wire between wire brackets is generally lifted to make it separate from the protruding part of the body to prevent high-voltage wire wear.  

(6) Connector fixing refers to the fixing part installed on the high pressure connector. The fixing part generally has an extra fixing head that can be inserted into the sheet metal hole of the body to fix the connector on the body or high pressure equipment.