323000324 - INTRODUCTION - BRAKING SYSTEM CONTROL/ADJUSTMENT DEVICES (A.B.S.)
DESCRIPTION OF COMPONENTS
Electrohydraulic unit
CompositionStructureThe unit consists 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- memorising the control parameters defined during the vehicle P.D.I.- memorising the software- processing the data acquired- controlling the braking process- detecting faults in the ABS components- memorising 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. Pump power supply +302. N.C.3. F serial line4. N.C.5. N.C.6. Right front wheel sensor signal7. N.C.8. N.C.9. N.C.10. N.C.11. N.C.12. N.C.13. Pump earth14. C-CAN L1 in15. C-CAN L2 out16. N.C.17. K line18. Right front wheel sensor supply19. Right rear wheel sensor supply20. Left rear wheel sensor signal21. N.C.22. Left front wheel sensor signal23. N.C.24. N.C.25. Valve power supply +3026. C-CAN H1 in27. C-CAN H2 out28. N.C.29. N.C.30. Brake light signal switch (NA)31. Right rear wheel sensor signal32. Power supply (+15)33. Left rear wheel sensor supply34. Left front wheel sensor supply35. N.C.36. N.C.37. N.C.38. Valve earth
Hydraulic control unit
SpecificationsFunctionIt performs the function of modulating the pressure of the fluid at the brake callipers via solenoids, with the following operating stages:- brake fluid pressure increase- brake fluid pressure maintenance- brake fluid pressure decreaseCompositionStructureThe hydraulic control unit consists of:- eight 2-way solenoids- a dual circuit scavenging pump- two low pressure accumulators- two high pressure accumulators
1 - Brake servo brake pump assembly2 - 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 phonic wheels.CompositionStructureActive sensors consist of two fundamental components:- a multipolar magnetic coding device (1) built into the wheel hub bearing (complete with controls)- a (magnetic-resistive) receiver (2) facing the codifier.FRONT SENSOR
REAR SENSOR
OperationThe active sensor functions on the basis of variation in the internal electrical resistance, according to the intensity and direction of the lines of force of an external magnetic field (multipolar magnetic coding device). It produces a variable square wave signal whose frequency varies according to the rotation speed of the wheel, but has a constant amplitude.The active sensor is therefore a proximity sensor with built-in electronic system, 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 phonic wheel is a multipolar ring, an elastomer with a certain number of magnetic particles which are lined up using a special magnetisation technique to form several magnets with alternate North or South polarity in a circumferential direction.
