Ebara Corporation

Shinichiro Arakawa

Hideo Ikeda

Kikuichi Mori

Kenichi Kajiwara

Isamu Ichiki

Renzo Ghiotto

Yukimasa Nakatsukasa

Shu Nagata

A pump casing made of sheet metal comprises a casing jacket having a cylindrical cup shape, an end plate formed at one side of the casing jacket, a casing flange formed at the other side of the casing jacket and a projecting portion radially outwardly bulged so as to have a volute shape. The end plate is axially outwardly bulged so as to have an arcuately curved surface, and the base portion of the projecting portion is located on the extension of the arcuately curved surface of the end plate so as to provide continuity from the end plate to the projecting portion. With the above structure, there is no portion where a great deal of bending stress caused by stress concentration is generated, and the pump casing has a sufficient strength and rigidity against not only piping forces but also internal pressure.

Pump casing made of sheet metal

A centrifugal pump casing of a centrifugal pump, includes a casing shell accommodating a rotary impeller therein and having as a basic circle an inner peripheral circle having a diameter greater than the diameter of the outer peripheral circle of the impeller. A bulged portion bulged radially outwardly is integrally formed on the outer peripheral wall of the casing shell, the bulged portion extends from a starting point remote from the winding starting point of the casing shell in a circumferential direction to an end point while gradually increasing in height in the direction from the starting point to the end point. A pipe-like discharge nozzle is connected with the casing shell so that it extends between the end point where the bulged portion is highest and the winding starting point where no bulged portion is formed. In this arrangement, since the bulge height above the basic circle is not so great even at the end point where a maximum height is reached, the bulged portion can be formed through only one pressing process without the need for an annealing process. Further, since the difference in height between the end point where the bulged portion is highest and the winding starting point where no bulged portion is formed is not so great, the wall portion of the casing shell at the winding starting point can serve as a guide; and accordingly, a guide for discharge water which is required in the prior art may be eliminated.

Method of manufacturing a centrifugal pump casing

A centrifugal pump casing of a centrifugal pump, comprising a casing shell accommodating a rotary impeller therein and having as a basic circle an inner peripheral circle having a diameter greater than the diameter of the outer peripheral circle of the impeller is disclosed. A bulged portion bulged radially outwardly is integrally formed on the outer peripheral wall of the casing shell, the bulged portion extends from a starting point remote from the winding starting point of the casing shell in a circumferential direction to an end point while gradually increasing in height in the direction from the starting point to the end point. A pipe-like discharge nozzle is connected with the casing shell so that it extends between the end point where the bulged portion is highest and the winding starting point where no bulged portion is formed. In this arrangement, since the bulge height above the basic circle is not so great even at the end point where a maximum height is reached, the bulged portion can be formed through only one pressing process without the need for an annealing process. Further, the wall portion of the casing shell at the winding starting point can serve as a guide, and accordingly, a guide for discharge water which is required in the prior art may be eliminated.

Centrifugal pump casing

A sheet-metal centrifugal pump casing comprising a casing shell having a suction port and being formed of a steel plate by means of deep drawing using a press, and having a suction flange firmly attached to the suction port of the casing shell is disclosed. The centrifugal pump casing further comprises a partition body firmly attached to the inner surface of the casing shell for partitioning a space within the casing shell into a suction chamber and a pressure chamber, and a diffuser which is integrally extended from the suction side end portion of the partition body and which tapers off toward peripheral edge of said suction port so that an axial gap is formed between the end edge of the diffuser and the peripheral edge of said suction port. Since the axial gap is formed between the end edge of the diffuser and the peripheral edge of the suction port, even in the case of the suction flange is acted upon by an external force such as by piping, a deformation does not affect the partition body, thus, problems such as contact between the partition body and the impeller may be completely avoided.

Sheet-metal centrifugal pump casing

A submersible pump comprising: a discharge casing open at the bottom thereof; a motor case fixed inside the discharge casing and containing therein a motor for driving an impeller; a support plate positioned so as to close an opening of the discharge casing for supporting the motor case; a downwardly concaved pump casing placed under the support plate for defining a pressure chamber between it and the support plate; and a downwardly concaved strainer placed under the pump casing for defining a suction chamber between it and the pump casing is disclosed. In this submersible pump, the discharge casing has an increased-diameter stepped flange integrally formed along the periphery of the opening of the discharge casing. Within a stepped portion of the stepped flange there are sequentially mounted respective peripheral portions of the support plate, of the pump casing, and of the strainer. The discharge casing and the support plate are fastened together by first bolts vertically extending therethrough, and in that the support plate, the pump casing and the strainer are fastened together by second bolts vertically extending therethrough. By this arrangement, the entire pump can be easily assembled by fastening the first and second bolts.

Submersible pump

A pump casing manufactured by press forming of steel plate and including a volute casing encircling a pump impeller so as to form a fluid path around the pump impeller is disclosed. The cross-sectional area of the fluid path is gradually increased towards a discharge port of the pump casing. The pump casing includes a casing body which is formed at first by press forming a metal plate into a cylindrical cup shape having an opening portion at one side thereof and a closed bottom portion at the other side of the same, and then by press forming the cylindrical cup shaped casing body so as to have a volute portion radially outwardly expanded from a cylindrical surface of the casing body at an axially intermediate portion thereof which radially opposite to the pump impeller, a casing flange outwardly extending from the opening portion and an aperture serving as a suction port at the bottom portion. Since no separate volute member is provided within the pump casing to form the volute portion, the outer diameter of the pump casing can be made small and also the shape of the fluid path in the volute casing can be made smooth.

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Kanagawa, Japan

Shinichiro Arakawa