Suspension - 悬挂

关于悬挂

  1. 非独立悬挂。轮轴之间被刚性连接。几乎只用在硬派的越野车上。
  2. 独立悬挂。每个轮子分别互不干扰。
    • 麦弗逊悬挂（MacPherson）-只有上臂没有下臂（衍生：双球节、查普曼）：（-）避振基本只能直上直下，操控性会略差；（+）最大程度的精简——轻且成本低；（+）给驱动空间，整体空间占用小。
    • 双叉臂（Double Wishbone）-一上一下双臂（升级：多连杆MultiLink）。（+）车轮上下运动时候，可以动态改变轮子的外倾角，操控性提升；（-）结构复杂，成本高；（-）阻挡驱动，占用空间大。
  3. 半独立悬挂。
    • 扭力梁（Torsion Beam）:（+）成本低；（+）不占用空间；（-）舒适操控差；（-）不能四轮定位。

Wheel alignment - 四轮定位

关于汽车四轮定位和悬挂调校, Wheel alignment - what is camber, caster and toe?

  1. Toe 前束 - 车轮前进方向的指向。
    • 前轮Toe-in（内八字）走直线更稳定，后轮Toe-in转弯更稳。Toe-out使得车更敏感，潜在危险。
  2. Camber 侧倾角 - 车轮侧面和地面垂直线的夹角。
    • 影响过弯的稳定性，调整轮胎的抓地。
  3. Caster 主销后仰角 - 转向运动时轴心与地面垂直线夹角。
    • 增加caster，增加方向盘的稳定性。

Manual Transmission

How a Manual Transmission and Clutch Works

Wheel Speed Sensor (ABS)

Wheel Speed Sensor Operation & Testing. The Difference Between Active and Passive Wheel Speed Sensors

  • Passive Wheel Speed Sensor : 2 wire permanent magnet, produces an AC voltage signal, generated when a toothed tone ring passes by the sensor.
  • Active Wheel Speed Sensor : look the same, (more accurate at lower speeds), output a digital signal DC square ware signal.

Electronic Control Unit

Understanding the CAN BUS - Part 1, Part 2 - Electrical Signals, Part 3 - The protocol, CAN synchronisation

  • CAN (Controller Area Network) BUS
    • Two twisted wires (twisted to reduce electromagnetic interference, and protect against the radio frequency interference) :
    • Need be terminated at both sides by 120 ohms resistor (might be implanted in modules).
  • Transceivers - transform the original signal to CAN HIGH (2.5V - 3.5V) and CAN LOW (1.5V - 2.5V) balanced signal (to make the message more recognizable).
    • 0 : CanH = 3.5 V, CanL = 1.5V; 1 : CanH = 2.5V, CanL = 2.5V.
  • Protocol
    • Data Frame. broadcasted, all connected devices can receive. (with arbitration - lowest ID win)
    • Remote Request Frame, require a can ID frame.
    • Error Frame. one controller is detecting errors in a data frame received, it will send out error frame if error detected, and everyone else will ignore that data frame.
    • Overload Frame. detection controller is busy.

ECU TESTING : Explained! CAN BUS Diagnosis – How to Troubleshoot Faults

  • Information needed:
    • OBD2 pin output.
    • Full wiring diagram for vehicle - modules connected to can bus, where potential fail could lie.
  • (1) Rule out a faulty battery.
  • (2) Check the can bus network if asleep. (voltage between 6 & 14)
  • (3) Test the can bus terminating resistance. (ohm between 6 & 14, should be 55-70Ω, since two 120Ω resistance at both end )
  • (4) Diagnosing for each module. (60Ω or 120Ω reading, short to ground/voltage)

Electrical Vehicle

EV Electrical Systems BASICS!, How an Electric Car Works?.

  1. High-Voltage System.
    • Battery, Charger, Converter & Inverter (change the currency & regeneration), Motor.
  2. Low-Voltage System.
    • Vehicle Accessories.
  3. Multiple CAN Networks.

Electric Vehicle Operation and Diagnosis