Filtering apparatus with rotatable filter elements and seal

A filter comprising:

• a housing defining a closed chamber;
• a hollow shaft rotatable in said chamber about an axis;
• a sleeve connected to said housing and centered on said axis;
• a plurality of filter elements connected to and rotatable with said shaft;
• means including a filtrant inlet opening into said chamber and a filtrate outlet opening into said shaft for passage of a suspension to be filtered from said inlet to said outlet through said filter elements;
• a pair of axially connected sealing surfaces connected to and rotatable with said shaft and annularly surrounding said axis;
• a pair of annular bellows-type seals each having a hollow interior and concentrically surrounding said shaft, said seals each having one axial end secured nonrotatably to said sleeve and an opposite axial end axially engageable with a respective one of said surfaces, and said seals each being axially extensible between a normal relaxed position with said opposite end spaced from the respective surface and an extending position with said opposite end bearing axially on the respective surface, said seals forming with said shaft and sleeve in the respective extended positions an annular compartment isolated from the interior of said shaft and from said chamber and annularly surrounding said shaft;
• means for introducing a clean liquid under pressure into said annular compartment between said seals and thereby flushing particles between said opposite ends and the respective surfaces;
• and
• means including a fluid passage opening into said hollow interior of said seals for pressurizing said interiors and thereby extending said seals into said extended positions. , 2. The filter as defined in claim 1,
• wherein said seals are made of metal. 3. The filter as defined in claim 1, wherein each of said seals has a portion engageable with said shaft member and is formed at said portion with throughgoing holes, whereby fluid under
• pressure in each of said seals can exit therefrom through said holes. 4. The filter as defined in claim 3, wherein said holes are passages opening at right angles to the surface of said respective seals at said
• portion. 5. The filter as defined in claim 3, wherein said holes are passages opening at non-right angles to the surface of said respective
• seals at said portion. 6. The filter defined in claim 1, wherein said surfaces each lie in a respective plane perpendicular to said axis.