125000353 - 3340A ABS CHECK/ADJUSTMENT DEVICES

DESCRIPTION OF COMPONENTS

Electro-hydraulic unit

Composition

StructureThe unit consits of an electronic control unit (1) and an electro-hydraulic control unit (2).

Electronic control unit

Specifications

Function

The electronic control unit carries out the following functions:

  • acquiring the data coming from the wheel rpm sensors
  • memorizing the control parameters defined during the vehicle P.D.I.
  • memorizing the software
  • processing the data acquired
  • controlling the braking process
  • detecting faults in the ABS components
  • memorizing the fault codes and activating the ABS and EBD warning lights
  • transmitting and receiving data via the C-CAN line
  • transmitting and receiving data via the diagnostic connector
PIN OUT
1 - Power earth2 - +30 power supply3 - N.C.4 - N.C.5 - Signal earth6 - +30 Supply7 - N.C.8 - N.C.9 - N.C.10 - N.C.11 - K diagnostic line12 - Left front sensor signal13 - Left rear sensor positive14 - Left rear sensor signal15 - Right front sensor positive16 - Left rear sensor signal17 - N.C.18 - N.C.19 - N.C.20 - N.C.21 - N.C.22 - N.C.23 - +15 Supply24 - CAN-H line25 - N.C.26 - N.C.27 - N.C.28 - Left front sensor positive29 - N.C.30 - Right rear sensor positive31 - Right rear sensor signal32 - N.A. stop button33 - N.C.34 - N.C.35 - N.C.36 - N.C.37 - VSO vehicle speed (recovery)38 - N.C.39 - N.C.40 - CAN-L line41 - N.C.42 - N.C.BASIC WIRING DIAGRAM
A - Solenoid valve relayB - Pump motor relayC - Pump motorD - Valve assemblyE - Electronic control unitFL - Left front sensorFR - Right front sensorRL - Left rear sensorRR - Right rear sensor1A-1B - Left front wheel solenoid valves3A-3B - Right front wheel solenoid valves4A-4B - Left rear wheel solenoid valves2A-2B - Right rear wheel solenoid valves

Electro-hydraulic control unit

Specifications

Function

It has the task of modulating the pressure of the fluid at the brake calipers via solenoid valves with the following operating stages:

  • brake fluid pressure increase
  • brake fluid pressure maintenance
  • brake fluid pressure discharge

Composition

Structure

the electro-hydraulic control unit is composed of:

  • eight 2-way solenoid valves
  • a dual circuit recovery pump
  • two low pressure accumulators
  • two high pressure accumulators
1 - Brake servo brake pump assembly2 - Electro-hydraulic control unit3 - Left rear wheel4 - Right front wheel5 - Left front wheel6 - Right rear wheel

Active sensors

Specifications

System details

The adoption of active sensors offers the following advantages:

  • less sensitivity to the distance between the sensor and the magnetic ring (gap)
  • a reduction in sensitivity to electro-magnetic interference
  • the capacity of the active sensor to measure wheel rpm speeds down to zero (instead of 2.5 km/h for passive sensors)
  • a saving in weight and dimensions
  • a simplification of the transmission couplings through the elimination of the flywheels.

Composition

Structure

Active sensors consist of two fundamental components:

  • a multipolar magnetic codifier (1) incorporated in the wheel hub bearing
  • a (magnectic-resistive) receiver (2) facing the codifier.
FRONT SENSOR
REAR SENSOR

Operation

General remarks

The active sensor operates according to the variation in the internal electrical resistance according to the intensity and direction of the lines of force of an external magnetic field (multipolr magnetic codifier) producing a variable square wave signal whose frequency varies according to the rotation speed of the wheel, but with a constant amplitude.The active sensor is therefore an integrated electronic sensor, connected by means of a cable to the ABS control unit, from which it receives an electrical supply and to which it transmits the speed of the vehicle.The flywheel is a multipolar ring, an elastomer with a certain quantity of magnetic particles which, by means of a special magnetization technique, are orientated to produce different magnets with alternate North South poles in a circumference arrangement.
1 - Magnetized seal2 - Bearing3 - Sensor head4 - Active sensor5 - Sealed connector