[0001] The present invention relates to a centrifugal pump driven by a synchronous motor
which - as is known - may indifferently be started in either of two opposite directions
of rotation.
[0002] Accordingly, centrifugal pumps driven by a synchronous motor are arranged substantially
as described in EP-A-0 207 430. More particularly, these pumps comprise a pressure
chamber, having a substantially circular cross-section, from which a delivery pipe
branches off radially; furthermore, an impeller having radial blades is provided in
the pressure chamber. Such a symmetrical structure is necessary in a centrifugal pump
driven by a synchronous motor, unless special uni-directional starting devices are
undesirably provided, in order to obtain equal hydraulic performances in both directions
of rotation of the impeller.
[0003] The performance of the pump is however reduced, mainly because of the incorrect alignment
of the delivery pipe with respect to the virtual direction of the fluid outflow, which
is substantially tangential to the inner periphery of the pressure chamber. As a consequence,
a portion of the pressurized fluid in the pump chamber tends to be re-circulated within
the chamber, instead of being delivered through the radial delivery pipe.
[0004] It is the scope of the present invention to provide a centrifugal pump driven by
a synchronous motor having simple construction and improved performances in both directions
of rotation of the impeller.
[0005] According to the present invention, this scope is attained in a centrifugal pump
driven by a synchronous motor embodying the features recited in the appended claims.
[0006] The characteristics and advantages of the invention will become more apparent from
the following description, given only by way of non-limiting example, with reference
to the accompanying drawings, in which:
- Figure 1 diagrammatically shows a cross-section of the centrifugal pump according
to the invention, in a preferred embodiment;
- Figure 2 diagrammatically shows a top view of the pump as in Figure 1.
[0007] With reference to the drawings, the centrifugal pump basically comprises a pressure
chamber 3 having a substantially circular cross-section and tapered towards a peripheral
outlet 4 from which a delivery pipe 5 branches off substantially radially. In addition,
the pressure chamber 3 is provided with a central suction inlet 6 which is substantially
concentric with respect to the drive shaft 7 of an impeller 8. The impeller 8 is formed
with substantially rectilinear radial blades 9 and the shaft 7 is rotatably driven
by a synchronous electric motor 10.
[0008] A baffle 11 is provided in the pressure chamber 3, adjacent to the outlet 4. Preferably,
the baffle 11 has a regular flat configuration, its width being just narrower than
the inner axial length of chamber 3, and in correspondence of its innermost end portion
12 is freely hinged on the side walls of the chamber along an axis which is substantially
parallel to the drive shaft 7. Furthermore, the end portion 12 of the baffle 11 is
disposed in the chamber 3 at a radial distance from the axis of the drive shaft 7
which is just longer than the radius of the impeller 8. The free end portion 13 of
baffle 11 is capable of abutting against the edge of outlet 4, such that the baffle
may freely pivot about its hinge axis between two angularly opposite operative positions.
In this connection, the edge of outlet 4 is preferably shaped accordingly, that is,
with at least two diametrically opposite rectilinear portions 14, 15 (Figure 2) against
which the baffle 11 can stop; for instance, the outlet 4 and at least a portion of
the delivery pipe 5 have a substantially square cross-section.
[0009] When the impeller 8 is driven by the motor to rotate in either a clockwise or anti-clockwise
direction, respectively, the fluid pressure inside the pressure chamber 3 causes the
baffle to abut against the outlet 4 in the position which in Figure 1 is shown with
continuous and dotted lines, respectively. In any case, the baffle 11 effectively
diverts towards the outlet 4 the fluid which in the chamber 3 is pressurized by the
impeller 8, with the result that the pump has an improved performance, substantially
equal in both directions of rotation.
[0010] It should be noticed, in addition, that the negligible gap provided between the baffle
11 and the periphery of the impeller 8 prevents possible solid foreign bodies from
getting stuck between the said two elements, where they could block the impeller 8.
[0011] The structural simplicity of the pump according to the invention should be apparent;
of course, a number of modifications may be provided without departing from the scope
of the invention. For example, the two operative positions of the baffle 11 may be
defined by respective projections (not shown), instead of the edge of the outlet 4,
which are preferably formed integrally with the pressure chamber 3.
1. Centrifugal pump comprising a pressure chamber having a substantially circular cross-section
and provided with a peripheral outlet from which a substantially radial delivery pipe
branches off, an impeller driven by a synchronous motor and formed with radial blades
being provided in the pressure chamber, characterized in that in the pressure chamber (3) are further provided, freely hinged on an axis substantially
parallel to the drive shaft (7) of the impeller (8), baffle means (11) capable of
moving between two angularly opposed operative positions in which a free end portion
(13) of the baffle means is adjacent to the edge of said outlet (4).
2. Centrifugal pump according to claim 1, characterized in that in said operative positions the baffle means (11) abut against the edge of said outlet
(4).
3. Centrifugal pump according to claim 2, characterized in that said baffle means (11) have a flat configuration and the edge of said outlet (4)
is formed with at least two substantially rectilinear portions (14, 15) against which
said baffle means (11) abut in said operative positions, respectively.
4. Centrifugal pump according to claim 1, characterized in that said baffle means (11) are hinged in correspondence of an end portion (12) thereof
which is disposed at a radial distance, from the axis of said drive shaft (7), just
longer than the radius of said impeller (8).
5. Centrifugal pump according to claim 1, characterized in that said baffle means (11) have a width that is just narrower than the inner axial length
of said pressure chamber (3), on the walls of which the baffle means are hinged.
