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2.4 DC THEORY OF OPERATION
IBP BOARD
The IBP board is an integrated board that contain the Main Procesor section and the Power supply section.
The operating voltage for the Main Processor is 5VDC and they are generated and supplied by the Power Supply
section.
These 5VDC are then supplied to the Optoencoder. The Main processor section transforms 5VDC in 3.3VDC to supply
the distance and diameter potentiometers.
INCREMENTAL ENCODER BOARD MAIN SHAFT
The optoencoder receives 5VDC from the Integrated Display. This voltage can be measured on the Integrated Display
at X6, pin 6. Output directly goes to the Integrated Display. The optoencoder is built so there are no adjustments.The
encoder disk consists of a re! ective slotted sleeve which is mounted on the main shaft and cannot be replaced unless
replacing the vibratory system.
DISTANCE POTENTIOMETER
The distance potentiometer is a 10K pot. It is supplied at 3.3 VDC from the Integrated Display. This input voltage can
be measured at the Integrated Display X7, pin 3. The output voltage is dependent upon the de! ection of the gauge
from the home position.
DIAMETER POTENTIOMETER
The diameter potentiometer is a 10K pot. It is supplied at 3.3 VDC from the main processor. This input voltage can be
measured at the Integrated Display X6, pin 3. The output voltage is dependent upon the rotation of the gauge from the
home position.
TRANSDUCERS
The transducers are installed in a manner that it forms a virtual transducer on each end of the shaft. This
con" guration gives the balancer greater accuracy along with minimal amount of erroneous readings. Both
measuring transducers are arranged in one plane. The transducers produce a charge output. The charge that is gene-
rated is sent back to the processor.
ELECTROMAGNETIC BRAKE
The PCB sends 150VDC to the Electromagnetic brake on the motor stopping the tire and wheel assembly at TDC for
the outside weight location. The voltage can be measured at X3 on the Integrated Display.
2.5 FUNCTIONAL DESCRIPTION
The wheel balancer is designed to compute static and dynamic imbalance of car, light truck, motorcycle wheels.
Wheel is clamped to the shaft using precision centering adapters and retainers and to compute correct imbalance
values, the parameters (diameter, width, and o# set) of the wheel to be balanced must be entered.
By sliding the 2D SAPE arm, the rim o# eset and diameter data are entered automatically and the rim width is entered
by sonar sensor.
The rotating shaft is perfectly balanced and rotates on precision bearings on the shaft support. The wheels clamped
normally represent an imbalance, which creates centrifugal force and a dynamic momentum as it is spun on the balan-
cer shaft. The wheel is spun by means of a motor.
The centrifugal forces created by any imbalance are detected by the two transducers located between the shaft sup-
port and the machine frame. These transducers contain small discs of special quartz which generate electric charge
when compressed. The charge created is linearly proportional to the compression force. Centrifugal force vectors are
generated by imbalances in the rotating wheel. This causes a signal to be generated by the transducers (which pick
up only one component of the constrained forces) in the form of a periodic sine wave.
The signal is not perfectly sinusoidal, due to noises from the suspension system, which add to the signal generated by
the imbalance of the wheel. To determine acutal imbalance the signal must be " ltered.
To " nd wheel imbalance, the transducers signal magnitude and encoder timing are both required.
A series of timing marks on the shaft that interrupt light transmitted between two optocouplers generate a DC Square
wave each time a mark moves past an optocoupler. One additional mark o# set from the encoders’ metallic strip, inter-
rupts a third optocoupler on the board, creating a zero-signal reset or home position.
The encoder detects 512 angular positions during each turn of the shaft, plus the home or reset position.
The frequency of the DC square wave generated by the encoder allows the balancer to compute shaft speed, wheel
acceleration and weight location. The encoder and transducer signals are multiplexed by the Processor section of the
Integrated Display, to give weight amount and location readings.
The Processor section gathers the information generated from the encoder and transducer via a ribbon cable. This
board is powered with 5VDC received from the Power Supply section of the Integrated IBP board.
Calculated imbalance values are then shown on the display after a spin cycle.
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