Smart Positioner
YT-1000 / 1050 series
Product Manual
Ver. 1.04
30
3. principle of positioner movement
3.1
Linear Positioner
Fig. 3-1: Linear positioner with an actuator
When INPUT SIGNAL is supplied to the positioner to open the valve, power is generated
from
①
the torque motor and pushes
②
the flapper to the opposite side of
③
the nozzle.
The gap between
③
the nozzle and
②
the flapper becomes wider and from inner part of
④
the pilot, left to
⑤
the spool, air inside
⑨
the chamber is exhausted through
③
the nozzle.
Due to this effect
⑤
the spool moves to the right. Then,
⑦
the seat which was blocked by
⑧
the poppet pushes the poppet away and supplied pressure (air) goes through
⑦
the seat
and OUT1 Port and enters into
⑩
the chamber of the actuator. Then
⑩
chamber’s pressure
will increase and when there is enough pressure inside the chamber to push the actuator’s
⑪
spring, a
ctuator’s
⑫
stem will start to go down and through the feedback lever, stem’s
linear motion will be converted to span
⑭
lever’s rotary motion. This span
⑭
lever’s rotary
motion will then once again rotate
⑮
the span and pulls
the spring. When the valve’s
position reaches to given input signal, span
⑯
spring’s pulling force and
①
torque motor’s
power will be balanced and move
②
the flapper back its original position to reduce the gap
between
③
the nozzle. The amount of air being exhausted through
③
the nozzle will reduce
and left to
⑤
the spool
⑨
the chamber pressure will increase again.
⑤
Spool will move
back to its original position on the left and
⑧
the poppet will also move in same direction
blocking
⑦
the seat to stop the air coming into the
⑩
chamber through the SUPPLY. As a
result, the actuator will stop operating and the positioner will return to its normal condition.