Volute shaped pump casing for a centrifugal pump

#This application claims the priority of European Application No. 10 166 566.9, filed Jun. 18, 2010, the disclosure of which is incorporated herein by reference.

#The invention relates to a volute shaped pump casing according to the preamble of claim 1 and to a centrifugal pump including such a volute shaped pump casing.

#Volute casing pumps are very common. Their characteristic feature is the volute-shaped pump casing which, as a rule, makes this pump type recognizable from the outside. Volute type casings can be built as part of a single stage or multistage pump arrangement. In some multistage pumps a volute shaped casing is provided only for the last stage. Single suction and double suction, double volute casing pumps are both used frequently.

#FIG. 1 is a section perpendicular to the axis of rotation through a conventional volute shaped pump casing having a double volute;

#FIG. 1A is a cross section through the outlet part of the conventional volute shaped pump casing in accordance with FIG. 1;

#FIG. 2 is a section perpendicular to the axis of rotation through an embodiment of a volute shaped pump casing according to the invention having a double volute;

#FIGS. 1, 1A and 3 show a conventional volute shaped pump casing 1 for a centrifugal pump, with FIG. 1 being a section A′-A′ perpendicular to an axis of rotation, FIG. 1A being a cross section C′-C′ through the outlet part and FIG. 3 being an axial section B′-B′ through the conventional volute shaped pump casing. The volute shaped pump casing shown includes a chamber for housing at least one impeller 4 mounted on a shaft 2 for rotation around an axis of rotation 2a when for example driven by a motor. The casing further includes a volute shaped chamber which forms a flow channel divided into a first volute 5.1 and a second volute 5.2 typically extending each over about half or less of the circle, and a first channel 6.1 and a second channel 6.2 connected to the first and the second volute respectively to guide the pumped medium out.

#The casing advantageously includes at least one wall 3 separating the first channel 6.1 from the second volute 5.2 and/or from the second channel 6.2, said wall 3 being called a rib or splitter rib or splitter rib wall. A leading edge part 7.1, 7.2 of the casing 1 which separates or guides the flow from a volute 5.1, 5.2 into a channel 6.1, 6.2 is designated cutwater lip or cut water and for any given length the top and bottom surface extending beyond the lip is termed the tongue. In the case of a casing with double volutes and double flow channels there are two cutwater lips 7.1, 7.2, with one of the cutwater lips being the leading edge part of the splitter rib 3 in the casing shown in FIG. 1.

#A conventional volute shaped pump casing with double volute and double discharge is arranged in such a way that the first channel 6.1, also called outer or long channel, is wrapped around the second volute 5.2, also called inner volute, and over the second channel 6.2, also called inner or short channel, so that the discharge of the pumped medium is made through a common discharge opening 8 which for example can be provided in a flange 8a. The final or last part of the channels 6.1, 6.2 can be arranged tangentially to the volute casing, as shown in FIG. 1 or arranged radially by providing e.g. a swan neck. The volute shaped pump casing can further include a suction duct or suction channel not shown in the Figures.