Hospira LifeCare XL Series, Technical & Service Manual

Page: 45 / 278

SECTION 4 THEORY OF OPERATION
430-00587-008 (Rev. 2/05) 4 - 20 Plum XL Series
Figure 4-3. Mechanism Valve Pins and Sensor Locations
4.3.2.3
INLET/OUTLET VALVE SUBSYSTEM
The inlet/outlet valve subsystem is similar in function and build to the primary/secondary
valve subsystem, but it does not contain a series of interrupters or a pin detection
assembly. Refer to
Section 4.3.2.2, Primary/Secondary Valve Subsystem , for the inlet/
outlet valve subsystem theory of operation.
4.3.2.4
PLUNGER DRIVE SUBSYSTEM
The plunger drive subsystem includes a stepper motor. The stepper motor rotates
approximately 1-2/3 revolutions per infusion system cycle to permit a 0.33 mL fluid
displacement every infusion system cycle. The stepper motor then reverses and the plunger
returns to home position. This cycle repeats for the duration of fluid administration.
Excluding the stepper motor, the plunger drive subsystem includes the following
components: ball thrust bearing, screw/coupler assembly, and plunger/support system.
The ball thrust bearing is positioned against the mechanism assembly chassis. As the
plunger extends into the cassette diaphragm to displace fluid, the resulting load (due to
pumping action and back pressure) is transferred axially through the ball thrust bearing
to the mechanism assembly chassis.
The screw/coupler assembly links the motor and the plunger. This assembly includes a
flag that passes through an interrupter module. This screw/coupler flag/interrupter
module combination is used in conjunction with predetermined factory calibration data
to determine the plunger position.
During operation, if the screw/coupler flag passes through the interrupter module at the
incorrect time sequence, a motor phase loss is detected.
PRIMARY VALVE
REGULATOR ACTUATOR
AIR-IN-LINE SENSOR
(DISTAL)
PRESSURE SENSOR
CASSETTE LOCATOR
OUTLET VALVE
PLUNGER
INLET VALVE
SECONDARY VALVE
(PIGGY BACK)
AIR-IN-LINE SENSOR
(PROXIMAL)
04K01003