Nilfisk-Advance CS7000 Fuel Cell EcoFlex, Руководство по обслуживанию

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354 Service Manual – CS7000
Steering System
Functional Description
Summary
The steering system utilizes steer by wire technology. The major electrical components are the Steering
Controller, Steering Wheel Rotation Sensor, Steering Actuator and the Steering Travel Limit Switches.
The Steering Controller receives input signals from the Steering Wheel Rotation sensor that tell it which
direction the steering wheel is turning and how fast it is rotating. Based on these inputs the Steering
Controller drives the Steering Actuator Motor with a three phase alternating current to rotate a gear. The
gear is meshed to a large ring gear that rotates the drive wheel assembly either right or left. The Steering
Controller also monitors two travel limit switches (proximity switches) that signal when the drive wheel has
steered to is maximum desired angle in either direction.
Steering Wheel Rotation Sensor
The Steering Wheel Rotation Sensor has an internal
“encoder” that translates steering wheel rotation
information into four digital signals. The end of the
steering shaft has a special “diametrically polarized”
magnet on it. The line of separation between the north
and south magnetic poles rotates in close proximity to
the encoder. The three images below show how a wire
on a clear plastic CD case rotates as the shaft rotates.
The encoder “reads” the movement of the magnetic
fields and creates a four 5v square wave signals.
There are two pairs of signals. For each pair, when
the steering wheel rotates, one of the signals switches
before the other so that the controller can tell which
direction the steering wheel is being turned. The second
pair of signals provides “redundant” information.
Steering Actuator Steering Wheel
Rotation Sensor
Proximity Sensor - Travel
Limit Switch
Steering Controller
The wire rotates with the magnetic field as the steering wheel rotation sensor shaft is turned
Encoder
Magnet
Steering
Shaft
(Rotates)