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Technical Details
8
8.1 Theory of Operation
A peristaltic pump is a fluid pump which operates to create a
moving region of compression along a flexible tube. The
motion of the compressed region of the tube along its axis
forces fluid ahead and creates a partial vacuum behind the
region. This partial vacuum forces more fluid forward. The
pump has a Rotor Assembly which rotates an attached set of
rollers up against a tube backed by a fixed circular wall called
the Stator. The rotary motion of the Rotor Assembly around
the center axis of the pump forms the region of moving
compression in the tube.
8.2 Design Considerations
One side effect of the friction between the Rollers and the
tube is a net force on the tube in its axial direction. When
unchecked, this force tends to cause the tube to "creep" or
move forward. A pump must have some type of mechanism
to counter this force. In addition, is must give customers the
ability to change the tubing quickly, to use the same pump
with a wide variety of tube diameters and materials, and to
stack more than one pump onto a motor.
8.3 Design Solution
The peristaltic pump provides a novel solution to today's
customer needs. In this design a Rotor Assembly consists of
two stainless steel rotors which sandwich three rollers
between ball bearings. The Rotor Assembly is rotated by a
Rotor Shaft, driven by a pump motor. The Rotor Assembly is
supported by a pump base. A stator is mounted to the Base
and acts as a tubing compression surface for peristaltic
pumping of fluid when in the closed position. In addition, the
tight fit of the mating areas of the Stator and the Lower Shield
(also mounted to the Base) acts to fully enclose the pump
region. This enclosure prevents splashing of fluid in the event
that the tubing fails and fluid leaks.
8-1
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