198002683 - 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. Power earth (engine and valves)2. Engine power supply +303. Valve power supply +304. Signal earth (on chassis)5. Left front sensor signal6. Left rear sensor positive7. N.C.8. Right rear sensor positive9. Right front sensor positive10. Right front sensor signal11. 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
Hydraulic control unit
SpecificationsFunctionIt performs the function of modulating the pressure of the fluid at the brake callipers via solenoids. It has 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:- a reduction in sensitivity to electro-magnetic interference- a saving in weight and size- a simplification of the transmission couplings through the elimination of phonic wheels.Thanks to the possibility of detecting very low speeds, the active sensors improve the precision of the on-board navigation systems.These systems update the position of the vehicle in the memorised maps via the GPS system: continuous information about the route travelled by the vehicle, even at low speeds, is therefore essential in calculating its exact position.CompositionStructureActive sensors consist of two fundamental components:- a multipolar magnetic coding device (1) built into the wheel hub bearing (complete with controls)- a Hall effect receiver (2) that faces the coding device.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.
