Guide and seal assembly for a piston of a drowned piston type pump

Claim 1

A guide and seal assembly for a piston of a drowned piston type pump comprising at least a chamber within which the said piston reciprocates to suck into and supply from the said chamber a liquid, the said seal assembly being arranged to guide the said piston and create a seal between the said chamber and the outside, characterized in comprising a ring delimited by a single inner cylindrical surface having a diameter substantially equal to the diameter of a seat in which the assembly is housed, the said ring having a first frontal seat for a first annular seal element having a substantially C-shaped cross-section with inner and outer diameters substantially equal to the corresponding diameters of the said ring, and an annular groove formed in the said inner cylindrical surface of the said ring and arranged to accomodate a second annular seal element of substantially U-shaped cross-section, having an inner diameter substantially equal to the said inner diameter of the said ring and an outer diameter smaller than the outer diameter of the ring itself, a first annular cavity formed in the said outer surface of the said ring and between the said seal elements, and a second annular cavity formed in the said inner surface of the said ring and between the said seal elements, the said annular cavities communicating with each other by means of at least a radial hole formed in the ring, and the said first annular cavity communication with at least a discharge hole for the liquid which gathers in the said first cavity.