Pump and a method of manufacturing such a pump

Abstract

The pump housing (2) includes a circumferential wall (3), a pump casing (20) and a shaft cover (40). The pump casing (20) is attached to the circumferential wall (3) by a plurality of connection elements. The pump casing (20) includes a central opening (27) to form an axial supply (14) of the pump housing (2) for material to be pumped. The circumferential wall (3) closes the pump housing (2) along its outer circumference. The pump (1) includes a plurality of connection elements (22) connecting the pump casing (20) to the circumferential wall (3). The connection elements (22) are positioned in groups along the circumference of the pump housing (2), wherein the groups are regularly distributed along the circumference of the pump housing (2).

Claims

1. A pump housing comprising a circumferential wall, a pump casing and a shaft cover, wherein the pump casing is attached to the circumferential wall and wherein the pump casing comprises a central opening to form an axial supply of the pump housing for material to be pumped, the circumferential wall being an outer wall of the pump housing, wherein the pump housing comprises connection means connecting the pump casing to the circumferential wall, wherein the connection means are positioned in groups along the circumference of the pump housing, each group comprising a plurality of connection means, wherein the groups are distributed along the circumference of the pump housing, wherein the connection means are formed by bolts, and bolt receiving holes provided on the circumferential wall and bolt receiving holes provided on the pump casing, wherein the circumferential wall comprises bolt receiving structures provided on the outer circumference of the circumferential wall, wherein the bolt receiving structures protrude in a radially outward direction, wherein each bolt receiving structure comprises at least two bolt receiving holes, wherein the pump casing comprises a plurality of reinforcing ribs positioned radially with respect to the central opening, wherein the connection means are positioned adjacent reinforcing ribs, and wherein the connection means of each group are positioned on opposite sides of the adjacent reinforcing rib.

2. The pump housing according to claim 1, wherein the connection means are positioned along the outer circumference of the pump housing and connect the pump casing to a radial outer wall of the circumferential wall.

3. A pump comprising a pump housing according to claim 1.

4. A method of manufacturing a circumferential wall for a pump housing, wherein the circumferential wall comprises bolt receiving holes provided on the outside of the circumferential wall, the method comprising: providing a mould for the circumferential wall, the mould comprising a plurality of casting openings, filling the mould with a liquid casting material by supplying the casting material to the mould via the casting openings, allowing the casting material to solidify in the mould, and removing the mould, wherein the bolt receiving holes are positioned in groups along the circumference of the circumferential wall, wherein the groups are regularly distributed along the circumference of the circumferential wall, wherein the circumferential wall comprises bolt receiving structures provided on the outer circumference of the circumferential wall, wherein the bolt receiving structures protrude in a radially outward direction, wherein each bolt receiving structure comprises at least two bolt receiving holes, and wherein the bolt receiving structures align with the casting openings and/or function as risers during casting.

5. The method according to claim 4, wherein the casting material is one of steel, cast steel, grey or white cast iron.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments will now be described, by way of example only, with reference to the accompanying schematic drawings in which corresponding reference symbols indicate corresponding parts, and in which:

(2) FIGS. 1 and 2 schematically show two different cross-sectional views of a pump according to the prior art,

(3) FIG. 3 schematically shows a perspective view of a pump housing according to an embodiment,

(4) FIG. 4 schematically depicts a side view of a pump housing according to an embodiment,

(5) FIG. 5 schematically depicts a detail of the pump housing according to an embodiment, and

(6) FIGS. 6a-6 b schematically depict a pump housing according to different embodiments.

(7) The figures are meant for illustrative purposes only, and do not serve as restriction of the scope or the protection as laid down by the claims.

DETAILED DESCRIPTION

(8) The embodiments will now be described with reference to the figures. FIGS. 1 and 2 show a pump according to the prior art and were discussed above.

(9) FIG. 3 shows an embodiment of a pump 1, a centrifugal pump, comprising a pump housing 2 with a circumferential wall 3, a pump casing 20 and a shaft cover 40 as described above. The circumferential wall spirals outwardly to form a tangential outlet 5, as shown in the figures.

(10) The pump housing 2 may be suitable for pumping a slurry comprising a mixture of water and dredged materials, such as sand, rocks etc. Therefore, the pump 1 is arranged to accommodate a rotor 7 comprising rotor blades 15, a shaft shield 11 and a suction shield 12 as described above.

(11) The pump casing 20 is formed as a lid arranged to cover the pump housing 2 and provide the pump housing 2 with additional strength. The pump casing 20 has a substantially disc shaped part 26, although the disc shaped part 26 may not have a circular outer circumference, as it may deviate from a circular shape at the position of the outlet 5. In the centre of the pump casing 20 a central opening 27 is provided to allow mass to be pumped to enter the pump housing 2 via the axial inlet 6 and axial supply 14. At the central opening 27 an inlet conduit 28 may be formed as integral part of the pump casing 20, the inlet conduit 28 protruding from the pump casing 20 in the direction of the axial rotation axis A, away from the shaft cover 40 (not shown in FIG. 3). The inlet conduit 28 may form the axial inlet 6.

(12) The pump casing 20 comprises a stepped part 23 forming a transition between the disc shaped part 26 and the inlet conduit 28, making the pump casing 20 strong. Furthermore, a plurality of reinforcing ribs 21 are provided. Each reinforcing rib 21 is substantially perpendicular with respect to the disc shaped part 26 and each reinforcing rib 21 is orientated in a different radial direction.

(13) Also provided is a shaft cover 40 forming the counterpart of the pump casing 20, positioned on the shaft side of the pump housing. The shaft cover 40 also comprises a central opening to allow the drive shaft 51 of motor 50 to pass through and drive the rotor 7 to rotate about axis A.

(14) As shown in FIG. 3, the connection means 22 (connecting the pump casing 20 to the circumferential wall 3) are provided in groups, such as pairs, positioned regularly, i.e. at regular intervals. This will be explained in more detail below with reference to FIG. 6.

(15) The connection means 22 are also positioned adjacent the reinforcing ribs 21. The term adjacent is used here to indicate that that the connection means 22 are positioned close to a reinforcing rib 21, for instance at least 5 times, preferably at least 10 times closer to the closest reinforcing rib 21 than to the second closest reinforcing rib 21.

(16) The connection means 22 may also be positioned close to the outer circumference of the pump casing 20, such that the connection means 22 engage the circumferential wall 3 at the position of the radial outer wall 32. In this case, the term ‘close to’ is used to indicate that the distance between the connection means 22 and the outer circumference of the pump casing 20 is less than 25%, or preferably less than 10%, of the radius of the pump casing 20, measured from the centre of the central opening 27 to the outer circumference of the disc shaped part 26.

(17) According to the embodiment shown in FIG. 3, the connection means 22 are provided in pairs, i.e. each reinforcing rib 21 has two associated, adjacent, connection means 20, which are provided symmetrically on both sides of the reinforcing rib 21. Of course, more than two connection means 22 may be provided in association with one reinforcing rib 21. In general, a group of connection means 22 may be provided in association with a reinforcing rib 21.

(18) In FIG. 3, connection means 22 are provided for each reinforcing rib 21. However, according an embodiment, some reinforcing ribs 21 may be without associated connection means 22, for instance the reinforcing ribs 21′ near the outlet 5.

(19) The connection means 22 may be any suitable connection means 22, such as clamping devices clamping the pump casing against the circumferential wall 3 or clamping the pump casing 20 and the shaft cover 40 together squeezing them against the circumferential wall 3.

(20) As shown in the Figures, the connection means 22 may be formed by a connection member 223, such as a bolt, and a corresponding bolt receiving hole 224 provided on the circumferential wall 3 and a bolt receiving hole 222 provided on the pump casing 20. This is shown in more detail in FIG. 5, showing part of the circumferential wall 3 and the pump casing 20.

(21) The circumferential wall 3 may be provided with bolt receiving members or bolt receiving structures 221 provided on the outer circumference of the circumferential wall 3, protruding from the spiral outer shape of the outer wall 32 of the circumferential wall 3, and comprising bolt receiving holes 21. The dashed line L shown in FIG. 5 shows the contour of the circumferential wall 3 as it would be without the bolt receiving structure 221, clearly showing that the bolt receiving structure 221 protrudes from the outer wall of the circumferential wall 3.

(22) One bolt receiving structure or structure 221 may comprise one or two bolt receiving holes 21.

(23) The bolt receiving holes 222, 224 are parallel to the axial rotation axis A of the pump, i.e. parallel to the direction in which the internal pressure of the pump 1 will try to move the pump casing 20.

(24) FIG. 5 further shows that the pump casing 20 may comprise annular slots 241 in which sealing members 242, such as O-rings, may be positioned to provide a fluid-tight connection between the circumferential wall 3 and the pump casing 20.

(25) The circumferential wall 3 may be provided with soft inserts 228 which are suitable for forming a threaded bolt receiving hole 224 therein.

(26) FIG. 4 shows a side view of the pump 1 in the direction of the axial supply 14. It can be seen that the reinforcing ribs 21 are all orientated in a different radial direction at regular mutual angles α. The reinforcing rib 21 or reinforcing ribs 21 close to the outlet 5 may be a bit longer or shorter in radial direction to follow the irregularity of the outer circumference of the pump casing 20 and the circumferential wall 3.

(27) The distribution of the connection means 22 will now be explained in more detail with reference to FIG. 6a-b, showing a view of the pump housing 20 in the direction of the rotation axis A.

(28) As shown, the connection means 22 may be positioned in groups, such as pairs (FIG. 6a) or in larger groups, for instance comprising four connection means 22, as shown in FIG. 6b. The groups are positioned along the circumference of the pump housing 2 and are regularly distributed along the circumference of the pump housing 2. A group may be defined as a number of connection means 22 that are relatively close to each other compared to other connection means 22 which thus do not belong to that group. A group may be defined as a plurality of connection means 22 whereby a largest distance between any two connection means of the group (d1 in FIG. 6b) is at least ½ the distance between each connection means of that group to the next closest connection means of a different group (d2 in FIG. 6b). This ratio may preferably be ⅓ or even ⅕. This definition also applies to a group of two connection means 22. FIG. 6a also shows distances d1 and d2, whereby d1<½d2, preferably d1<⅓ d2 or d1<⅕ d2.

(29) The term regularly distributed is used to indicate that the groups are distributed along the circumference of the pump housing 2 at substantially constant angles α as shown in FIGS. 6a-b when seen from a centre point of the pump housing 2. In FIGS. 6a-6 b there are sixteen groups at a mutual angle α=(360/16)°. The term substantially constant is used to indicate that the different angles deviate less than 5°, preferably less than 2° with respect to each other.

(30) Alternatively, the term regularly distributed may be used to indicate that the groups are distributed along the circumference of the pump housing 2 at substantially constant intervals. The term constant is used to indicate that these distances do not deviate more than 15%, preferably less than 10%.

(31) According to an embodiment, the groups are regularly distributed along a substantial part of the circumference of the pump housing 2, whereby the substantial part of the circumference of the pump housing 2 forms at least 75% of the total circumference, so is at least 270°.

(32) Manufacturing a pump 1 or a pump housing 2 as described above may involve casting one or more of the pump parts, such as the circumferential wall 3.

(33) The bolt receiving structures 221 or bolt receiving structures provided on the outer circumference of the circumferential wall 3, protruding from the outer wall of the circumferential wall 3 allow for an advantageous casting process.

(34) The casting mould 230 is provided with casting openings 232 to supply casting material into the mould 230 (see FIG. 3). The bolt receiving structures 221 can be aligned with the casting openings 232 of the mould 230 providing an excellent structure for supplying the casting material into the casting mould. This saves material and thus cost with respect to supplying casting material at other positions.

(35) Also, the bolt receiving structures 221 can advantageously function as risers. During the casting process, the casing material inside the mould will solidify and thus shrink. Risers can function as a buffer reservoir for casting material. Once the material inside the mould has shrunk, the space in between the mould and the shrunk casting material will be filled with casting material from the risers. The risers may not be too small, as this will cause the casting material to cool down relatively quickly compared to the cooling of the rest of the casting material in the mould.

(36) Shaft Cover

(37) It is noted that all the configurations and embodiments of the connection means as described above may also be applied to the connection means 42 connecting the shaft cover 40 to the circumferential wall 3. These connection means 42 may also be positioned in groups along the circumference of the pump housing 2, wherein the groups are regularly distributed along the circumference of the pump housing 2. The shaft cover 40 may comprise a plurality of reinforcing ribs positioned radially with respect to a central opening for the drive shaft, wherein the connection means 42 are positioned adjacent the reinforcing ribs. The connection means 42 of a group may be positioned on opposite sides of the adjacent reinforcing rib. The connection means may be positioned along the outer circumference of the pump 1 and connect the shaft cover 40 to a radial outer wall 32 of the circumferential wall 3. The connection means 42 may be formed by a connection member, such as a bolt, and bolt receiving holes provided on the circumferential wall 3 and bolt receiving holes provided on the shaft cover 40. The circumferential wall 3 may comprise bolt receiving structures provided on the outer circumference of the circumferential wall. Each bolt receiving structure may comprise two bolt receiving holes.

(38) Advantages

(39) The embodiments described provide a pump, which is relatively strong and stiff. The pump can be casted in an efficient way, still resulting in a pump which is strong and stiff.

(40) The descriptions above are intended to be illustrative, not limiting. It will be apparent to the person skilled in the art that alternative and equivalent embodiments of the invention can be conceived and reduced to practice, without departing from the scope of the claims set out below.