184000328 - 3340A ABS CHECK/ADJUSTMENT DEVICES

COMPONENT DESCRIPTION

Electrohydraulic unit

Composition

StructureThis consists of an electronic cotnrol unit (1) and an electro-hydraulic control unit (2).

Electronic control unit

Specifications

Operation

The electronic control unit performs the following functions:

  • downloading data from the wheel rpm sensors
  • memorizing the control parameters defined during the preparation of the vehicle
  • memorizing the control software
  • processing the data acquired
  • controlling the braking process
  • detecting ABS component faults
  • memorizing fault codes and activating the ABS and EBD warning lights
  • sending and receiving data via the C-CAN line
  • sending and receiving data via the diagnostic connector.
ABS/EBD PIN OUT
1. Power earth2. +30 supply3. +30 supply4. Signal earth (on chassis)5. Left front sensor signal6. Rear sensor positive left7. N.C.8. Rear sensor positive right9. Front sensor positive left10. Right front sensor signal11. ABS tester k line12. N.C.13. Signal for ABS warning light14. C-CAN L15. C-CAN L16. 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 H26. C-CAN H

Hydraulic control unit

Specifications

Operation

Responsible for modulating the pressure of the fluid at the brake calipers via two solenoid valves with the following stages:

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

Composition

Structure

The electro-hydraulic control unit consists of:

  • eight two-way solenoid valves
  • a dual circuit electric recovery pump
  • two low pressure accumulators
  • two high pressure accumulators
1 - Brake servo pump2 - Hydraulic control unit3 Rear left wheel4 - Front right wheel5 - Front left wheel6 - Rear right wheel

Active sensors

Specifications

Features of the system

The adoption of active sensors offers the following advantages:

  • less sensitivity to the distance between the sensor and the magnetic ring (gap)
  • it reduces sensitivity to electro-magnetic interference
  • the active sensor is able to measure wheel rpm speeds down to zero (instead of 2.5 km/h with the passive sensor)
  • it produces savings in weight and size
  • it simplifies the transmission couplings through the elimination of the phonic wheels.

Composition

Structure

The active sensors consist of two basic parts:

  • a magnetic multi-polar codifier (1) integrated in the instrumented wheel hub bearing
  • a 'magnetic-resistive' receiver (2) opposite the codifier.
FRONT SENSOR

Operation

Introduction

The operation of the sensor is based on the variation in the internal electrical resistance depending on the intensity and the direction of the lines of force of an external magnetic field (multipolar magnetic codifier) producing a variable square wave signal whose frequency depends on the rotation speed of the wheel, but whose range is constant.The active sensor is thus a proximity sensor with its own electronic system. It is connected to the ABS control unit by means of an electrical supply cable and sends vehicle speed information to the control unit.The phonic ring is a multipolar ring, an elastomer with a certain quantity of magnetic particles which are aligned by means of a special magnetization technique to produce different magnets with alternating north and south polarity around the circumference of the ring.
1 - Magnetised sealing ring2 - Bearing3 - Sensor head4 - Active sensor5 - Sealed connector