(under subclass 437) Apparatus in which a single pump chamber includes two or more pumping members.
(1) Note. The plural pumping members may act upon the pump fluid within the single chamber either simultaneously, successively, or selectively.
(2) Note. For purposes of this definition, the pump chamber is construed as including only that chamber volume formed downstream of valve means controlling inlet of pump fluid to the chamber and upstream of valve means controlling discharge pump fluid from the chamber.
(3) Note. The plural pumping members under this definition may be laterally spaced, coaxial, or concentric and each must be disclosed as positively driven to act upon fluid within the pump chamber. However, in the case of concentric pumping members, the pumping faces thereof must be either axially spaced or relatively movable, e.g., a pumping member having a sealing ring or separable drive rod portion forming a portion of the pumping face is considered to be a single pumping member and is excluded under this definition.
SEE OR SEARCH THIS CLASS, SUBCLASS:
215+, for plural pumping members in a single chamber with condition responsive control of a drive transmission to change the phase relationship of the pumping members.
SEE OR SEARCH CLASS 92, Expansible Chamber Devices,
6, for a working member having a selectively variable end face area, and subclasses 60+ for a resiliently biased nonworking member movable wall in constant communication with a working chamber.
