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(11) | EP 2 366 905 A3 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Improved tight multi-stage pump |
| (57) The invention is a multi-stage pump (1) comprising an external jacket (2) with a
suction port (3) and a delivery port (4), provided at one end with a casing cover
(5) and at the opposite end with a lantern bracket (6) supporting an electric motor
(7) associated with rotary pumping members (8). The casing cover (5) and the lantern
bracket (6) are coupled to the ends of the external jacket (2) through fixing means
with the interposition of annular gaskets (17). Each gasket is housed in an annular
seat (18) defined by a shaped annular area (19) present in the casing cover (5) and
the lantern bracket (6) and by a counter-shaped annular area (20) present in the corresponding
end of the external jacket (2), opposing each other. The counter-shaped annular area
(20) comprises an annular counteracting surface (20a), inclined with respect to the
longitudinal axis (Y) defined by the external jacket (2), suited to compress the annular
gasket (17) when the casing cover (5) and the lantern bracket (6) are coupled to the
external jacket (2) through the tie rods. The external jacket (2) is provided with
a plurality of shaped annular portions (28) suited to make the external jacket (2)
elastically yielding along the direction defined by its longitudinal axis (Y) and
the fixing means comprise a plurality of tie rods (12) each one of which is provided
with a first end (12a) constrained to the casing cover (5) and a second end (12b)
constrained to the lantern bracket (6).
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