ELECTRICAL
4 - 4
CX EXCAVATORS
RPM CONTROL
Throttle Motor, CX130/CX160
1) The engine speed on the CX130/CX160 excavators is adjusted with a stepper motor.
Stepping Motor
A stepping motor is a motor that rotates when synchronization is turned into a pulse signal
from a pulse oscillator.
When using a stepping motor, the pulse oscillator is what determines rotational speed and
rotation degree. The driver circuit is what switches to change the current in the stepping
motor. It is necessary to amplify the signal in order to drive the stepping motor.
Pulse Oscillator
This circuit develops the pulse signal that determines rotation degree and rotational speed of
the stepping motor. A stepping motor rotates synchronizing with the pulse signal, which is
turned into an oscillation from this circuit. There are 1023 pulses in 52° of motor shaft
rotation.
Driver Circuit (throttle driver)
Driver circuit of a stepping motor consists of the logical section which forms and distributes a
pulse signal from an oscillator, and an amp section which amplifies and supplies a signal to
the motor. In other words, it is a circuit sending current by the decided sequence to the motor
coil at the pulse output from an oscillator. This “excitation method” excites the coil by the
decided order.
The output shaft of the throttle motor can turn 52°.
There are 1023 pulses in 52° of shaft rotation.
One pulse equals 0.05°.
There are limit switches inside the motor on both ends of motor rotation.
One motor pulse = 1.8° and the gear reduction of the motor to output shaft is 1/35.37, so
throttle output shaft rotation = .05 / pulse.
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