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CHAPTER 2 THEORY OF OPERATION
Effective
09/2005
ENCODER
The encoder is built into the shaft with no adjustments. The encoder disk is built onto the shaft and cannot be
replaced without replacing the vibratory member.The new incremental encoder is fitted in the vibratory tube and
consists of a reflective slotted sleeve which is mounted on the main shaft and the optoelectronic unit. To prevent
dirt and light entering, the opening in the vibratory tube
must
be sealed with black adhesive (electrical tape)
tape. A red visible LED and four light detectors are fitted in the encoder part of the optoelectronic unit, behind
the lenses. Part of the light is reflected back from the webs of the slotted sleeve to the encoder part and fo-
cussed by the lens, such that the web-slot pattern of the sleeve is mapped on the four light detectors. Two light
detectors are connected to one amplifier respectively in the encoder part. The difference in brightness between
the detector pairs determines the instantaneous output states of channels A and B. To exclude interference
from extraneous signals and to guarantee EMC-reliability, the two signals are amplified by an IC. One slot in the
sleeve is wider than the other 255 slots. Therefore the absolute angular position of the main shaft can be deter-
mined at constant rotating speed. The surface of the slotted sleeve must be clean and shiny, the slots must
have a dull black background. Should a dirt particle have settled on a web or in a slot, it can be lifted off of the
slotted sleeve with self-adhesive tape by applying it onto a strip of strong paper so that half of the tape is on the
paper and the other half overhanging.
CAUTION!
If the slotted sleeve is twisted relative to the main shaft when
being cleaned, the step Compensation of residual shaft unbalance has to be carried out with P84. A defective
slotted sleeve cannot be replaced in the field because the ball bearings of the main shaft are pressed in. The
incremental encoder can be checked with test functions P36.
ELECTRONIC BRAKE
The brake solenoid is provided with 12VDC to brake the balancer. This system has been used on other
balancers with great success.
While the balancer is spinning, the main processor pcb is gathering information
from the encoder and transducers. After the needed information is gathered the main pcb sends a signal to
the power supply pcb which sends 12VDC to the brake solenoid braking the balancer and bringing the shaft to
a stop.
SAPE (SEMI-AUTOMATIC-PARAMETER-ENTRY)
The handspin balancer utilizes a 1D SAPE to automatically input the distance from the balancer to the inside
weight location. The SAPE plugs into the main processor at connection X6. As the SAPE is pulled out
towards the wheel the voltage changes the correct distance is determined using the calibrated values.
VIBRATORY SYSTEM
The vibratory member is the foundation of the balancer. It houses the encoder and transducers along with a
temperture sensor for the tranducers.