199002181 - INTRODUCTION - BRAKING SYSTEM CONTROL/ADJUSTMENT DEVICES (A.B.S.)
DESCRIPTION OF COMPONENTS
Electrohydraulic unit
CompositionStructureThe unit consits of an electronic control unit (1) and an electro-hydraulic control unit (2).
Electronic control unit
SpecificationsFunctionThe electronic control unit carries out the following functions:- acquiring the data coming from the wheel rpm sensors- memorises the control parameters defined during the vehicle P.D.I.- memorizing the software- processes the data acquired- controls 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 connectorABS/EBD PIN OUT
1. Power earth2. +30 engine power supply3. +30 valve power supply4. Signal earth (on chassis)5. Left front sensor signal6. Left rear sensor positive7. N.C.8. Right rear sensor positive9. Left front sensor positive10. Right front sensor signal11. N.C. ABS diagnostic K line12. N.C.13. N.C.14. C-CAN L115. C-CAN L216. Left front sensor positive17. Left rear sensor signal18. Power supply (+15)19. Right rear sensor signal20. STOP signal21. N.C.22. N.C.23. Speedometer signal24. N.C.25. C-CAN H126. C-CAN H2
Electrohydraulic control unit
SpecificationsFunctionIt performs the function 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 decreaseCompositionStructureThe electro-hydraulic control unit consists of:- eight 2-way solenoid valves- a dual circuit scavenging 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
SpecificationsSystem detailsThe 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 size- a simplification of the transmission couplings through the elimination of the flywheels.CompositionStructureActive 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
OperationThe 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.
