Rotary piston pump with pressure equalization chambers for the shaft split seals

Claim 1

A rotary piston pump comprising a casing and partitions within said casing and defining therein an expansion chamber having opposite sides with a gear and bearing chamber on one side of said expansion chamber and a bearing chamber on the opposite side with said partitions separating said gear and bearing chamber and said bearing chamber from said expansion chamber, at least two shafts each extending between said gear and bearing chamber and said bearing chamber through said partitions into said expansion chamber, said partitions forming passages for receiving said shafts, split seals provided in said shaft passages and separating said gear and bearing chamber and said bearing chamber from said expansion chamber, each said split seal comprising two parts, said partitions defining pressure equalization chambers located between said gear and bearing chamber and said expansion chamber and between said bearing chamber and said expansion chamber and extending across said shaft passages and separating said two parts of said split seals, oil filters arranged between said pressure equalization chambers and the adjacent said gear and bearing chamber and bearing chamber located on the same side of said expansion chamber for equalizing the pressure difference therebetween, at least one of said casing and partitions form bores opening into said pressure equalization chambers, and vacuum-tight inspection windows arranged in said bores.