US3280752A

US3280752A - Pumps

Info

Publication number: US3280752A
Application number: US407498A
Authority: US
Inventors: Luhmann Reinhold
Original assignee: Siemen and Hinsch GmbH
Current assignee: Siemen and Hinsch GmbH
Priority date: 1963-10-31
Filing date: 1964-10-29
Publication date: 1966-10-25
Anticipated expiration: 1983-10-25
Also published as: DE1528822B2; CH417341A; GB1074796A; NL6412635A; DE1528822A1; NL147515B

Description

R. LHMANN Oct. 25, 1966 PUMPS 3 Sheets-Sheet l Filed Oct. 29, 1964 ngz Oct. 25, 1966 n. LUHMANN 3,280,752

PUMPS Filed Oct. 29, 1964 5 Sheets-Sheet 2 Oct. 25, 1966 R. LUHMANN 3,280,752

PUMPS Filed Oct. 29, 1964 3 Sheets-Sheet 3 United States Patent O 3,280,752 PUMPS Reinhold Lhmann, Itzehoe-Tegelhorn, Germany, assignor to Siemen & Hnsch m.b.H., Itzehoe, Holst, Germany, a corporation of Germany Filed Oct. 29, 1964, Ser. No. 407,498

Claims priority, application Germany, Oct. 31, 1963,

3 Claims. (Cl. 103-96) This invention relates to a side channel centrifugal pump with a side channel open to an open impeller wheel and ilow baille rribs in the side channel.

Side channel centrifugal pumps are known to have a steep delivery capacity characteristic curve. The delivery lhead normally :rises linearly with decreasing delivery ilow, in the same way as the power requirements. These pumps have poor eillciency at low delivery ilow rates and with a delivery ilow of zero they absorb maximum power. In many cases in operation, the delivery point of the pump cannot always be accurately maintained in one position and it may be possible that the pump is also driven for a short period against a closed pressure side, that is with zero delivery ilow. The associated motor must be made correspondingly large, even when the pump normally only operates in the range of the higher delivery ilows and operation with low delivery ilow or with the pressure side closed only seldom oocurs.

It is known that in the case of side channel pumps of large dimensions whose side channel cross-section is formed as a semicircle and in which there is not an open side channel, with baille ribs arranged in the inner zone of the side channel, the delivery capacity characteristic curve can be flattened oif in the range of the lower delivery ilows. With this construction however the baille ribs extend tightly against the impeller wheel and the construction of this pump is made very expensive by the special construction of the cross-section of the side channel. This type of construction is therefore not suitable for pumps with a low delivery capacity.

Through the invention a side channel centrifugal pump with the side channel open to an open impeller wheel formed from straight or singly curved vanes is obtained, which does not have the disadvantages mentioned, but still has in the range of the lower delivery ilows a downward `deflection of the delivery capacity and power absorption curves. It is proposed to arrange at least one baille rib in the side channel, which rib extends from the bottom of the channel over about half to three quarters of the height of the channel. It has been found to be superiluous to take those baille ribs right to the rotor, as directly at the impeller wheel an uncontrollable flow direction prevails, which can therefore be locally very diversiiied, nor can it be positively iniluenced by baille ribs.

For similar reasons it is advantageous to arrange the baille rib or ribs, viewed radially, only in the central zone of the side channel and to leave free in each case in the inner and outer zone of the side channel about a quarter of its radial extent.

It has also been found advantageous for technical reasons connected with production to make the baille rib or ribs in the side channel singly curved, so that it or they can be produced in the open casting. This does not affect the action of the rib or ribs.

If it is desired to have a Hat-extending delivery capacity characteristic curve over the whole delivery capacity range of the centrifugal pump, it is advisable to arrange in the side channel only one rib extending concentrically to this.

If a multiplicity of ribs are provided in the side channel, they preferably extend inclined to the impeller wheel hub, viewed in the delivery direction, with a slight curvature outwards. Through the angular position the size ICC and curvature of the ribs, the characteristic curve of the pump can be affected, that is t-he point can thereby be determined starting from which the delivery capacity curve and the power absorption curve rise more flatly.

A further proposal of the invention likewise envisages as simple as possible a 'construction of the foundry pattern, by the free longitudinal edge or edges of the rib being made to extend parallel to the plane of the impeller wheel.

In order primarily not to disturb the ilow in the suction slot zone and to obtain favorable entry conditions through the suction aperture into the side channel, -it is further proposed according to the invention that between the suction aperture end of the side channel .and the (according to circumstances) iirst rib in the side passage viewed in the peripheral direction, there is a distance of at least two or three pitches of the impeller wheel.

For similar reasons it is ladvisable that there should be a distance of at leas-t one to two vane pitches of the impeller wheel between the (according to circumstances) last rib lin the side channel and the beginning of the side channel discharge aperture.

The invention will now be described by way of example with reference to the accompanying drawings, in which:

FIGURE 1 shows the characteristic curve of a pump with and without baille ribs in the side channel,

FIGURE 2 shows the power requirement of the pump,

FIGURE 3 is a view of the side channel component of a vertical pump embodying the invention with a number of baille ribs in the side channel,

FIGURE 4 shows a cross-section through the side channel component represented in FIGURE 3, taken along the section line 4 4,

FIGURE 5 is la view of the side channel component of a pump embodying the invention with only one rib extending concentrically to the side channel, and

FIGURE 6 is a cross-section through the side channel component represented in FIGURE 5 taken along the section line 6 6.

In FIGURES l and 2 the values Q-H or O'N for a pump wit-hout baille ribs in the side channel are shown in dashed line, and the Values for a pump with baille ribs in the side channel are shown in sol-id line.

With delivery ilow less than 2O cubic meters per hour, in the case of the pump with baille ribs in the side channel the delivery head still only rises very slightly and, as can be seen from FIGURE 2, the same thing applies in the case of the power consumption. With a pump with baille ribs a motor can be chosen that is smaller by one or even two sizes than that required for the pump without baille ribs, which obviously advantageously affects the total cost price of the unit.

FIGURES 3 and 4 are views of a side 10 of a casing 12 for an impeller wheel 14 (shown diagrammatically). The side has a channel component having a multiplicity of baille ribs, in which the suction and pressure slots or apertures are arranged on the same side of the impeller Wheel. The impeller wheel 14 is of conventional construction and has a rotor 16, which is rotatable, and is provided with radially extending blades 18 that sweep over the side 10. The side channel 1 is deilned by a concave surface in the side and is bounded externally by a contour or side portion 2 and inwardly by a contour or side portion 3 and has a bottom portion. The delivery liquid arrives through a suction aperture 4 and discharges through la pressure aperture 5. The concave surface channel has an abutment end 1a which communicates with the suction intake aperture 4 and an abutment end 1b which communicates with the outlet aperture 5. In the side channel 1 are located ilow baille ribs 6, which exert the same advantageous eilect on the characteristic curves of the pump as already described. Each rib has a leading edge 6a and, downstream from the leading edge, a trailing edge 6b. l

As can be seen from FIGURE 4, the ribs extend from the bottom of the channel about over half to three quarters the depth of the concave surface channel 1.

As can also be seen from FIGURE 4, the bafe ribs 6 are arranged only in the radially central zone of the side channel and a free space or zone is provided radially outwardly and inwardly of the ribs in the side channel of each case.

The free longitudinal edges 6a of the ribs extend parallel to the plane of the rotor. A free space likewise exists between the end of the suction aperture and the beginning of the rst baffle rib in the side channel, which free space is equivalent t-o at least two/three vane pitches of the impeller wheel, in order not to disturb the ow conditions in the suction slot of the pump. For similar reasons a space is left free between the last baffle rib in the side channel 1 and the pressure aperture 5, which space is to be equivalent to at least about one to two vane pitches.

FIGURES 5 and 6 show a casing and channel arrangement identical to that of FIGS. 3 and 4 (s-o that like reference numerals are used to refer to the same parts) except that only one rib 7 is provided extending concentrically to lthe side channel. With this construction again, with only one concentric rib in the side channel a free space as described above remains between the end of the suction aperture 4 .and the beginning of the rib 7 and also between the end of the rib 7 and the beginning of the pressure aperture 5. The rib 7 has a free longitudinal edge 7a spaced from the impeller wheel (not shown but the same as that shown in FIG. 4).

The sizes and if requisite the number of the ribs to be provided must be adapted in this connection to the size .and shape of the side channel and may vary according to different pump sizes.

What I claim is:

1. A centrifugal pump comprising a rotatable impeller wheel having a rotatable rotor and vanes radially extending from the rotor, a casing formed as a body of revolution and having a side facing the impeller wheel, said side being formed with an arcuate channel concentric to the axis of the rotor and open to the vanes, said vanes dehning pockets opening to the channel, said channel being formed substantially concave in the side of the casing and being defined by a substantially concave surface and being yspaced away from the vanes in adirection longitudinally parallel with the axis of rotation of the rotor, said channel having closed ends, one of the ends of said concave surface channel being in communication with an intake suction aperture formed in the casing and the other end of said concave surf-ace channel being in communication with an outlet pressure aperture formed in the casing, said concave surface channel having a bottom portion and opposing side portions, at least one flow baffle rib positioned in the concave surface channel between the intake and outlet apertures, said rib extending from the bottom portion of the concave surface channel in -a direction toward the vanes of the impeller wheel to an extent at least over half but less than three quarters of the depth of the concave surface channel and having a free longitudinal edge disposed parallel to and spaced away from the vanes and said rib being spaced from the side portions of the -concave surface channel so that the concave surface channel has inner and outer free radial zones on opposite sides of the rib.

2. The invention of claim 1, wherein a plurality of ribs are provided, each of said ribs being curved and the ribs being spaced apart circumferentially in the concave surface channel and having outer longitudinal free edges which lie in a common plane.

3. The invention of claim 2, wherein said ribs include a rst rib adjacent the intake aperture and a last rib adjacent the outlet aperture, said rst rib being spaced from the intake aperture a distance of approximately three vane pitches of the impeller wheel and the last rib being spaced from the outlet aperture a distance of approximately two vane pitches of the impeller wheel.

References Cited by the Examiner UNITED STATES PATENTS V2,015,200 9/1935 Spoor 103-96 2,923,246 2/ 1960 Wright 103-96 FOREIGN PATENTS 448,265 5/ 1948 Canada. 581,808 8/ 1933 Germany.

MARK NEWMAN, Primary Examiner.

HENRY F. RADUAZO, Examiner.

Claims

1. A CENTRIFUGAL PUMP COMPRISING A ROTATABLE IMPELLER WHEEL HAVING A ROTATABLE ROTOR AND VANES RADIALLY EXTENDING FROM THE ROTOR, A CASING FORMED AS A BODY OF REVOLUTION AND HAVING A SIDE FACING THE IMPELLER WHEEL, SAID SIDE BEING FORMED WITH AN ARCUATE CHANNEL CONCENTRIC TO THE AXIS OF THE ROTOR AND OPEN TO THE VANES, SAID VANES DEFINING POCKETS OPENING TO THE CHANNEL, SAID CHANNEL BEING FORMED SUBSTANTIALLY CONCAVE IN THE SIDE OF THE CASING AND BEING DEFINED BY A SUBSTANTIALLY CONCAVE SURFACE AND BEING SPACED AWAY FROM THE VANES IN A DIRECTION LONGITUDINALLY PARALLEL WITH THE AXIS OF ROTATION OF THE ROTOR, SAID CHANNEL HAVING CLOSED ENDS, ONE OF THE ENDS OF SAID CONCAVE SURFACE CHANNEL BEING IN COMMUNICATION WITH AN INTAKE SUCTION APERTURE FORMED IN THE CASING AND THE OTHER END OF SAID CONCAVE SURFACE CHANNEL BEING IN COMMUNICATION WITH AN OUTLET PRESSURE APERTURE FORMED IN THE CASING, SAID CONCAVE SURFACE CHANNEL HAVING A BOTTOM PORTION AND OPPOSING SIDE PORTIONS, AT LEAST ONE FLOW BAFFLE RIB POSITIONED IN THE CONCAVE SURFACE CHANNEL BETWEEN THE INTAKE AND OUTLET APERTURES, SAID RIB EXTENDING FROM THE BOTTOM PORTION OF THE CONCAVE SURFACE CHANNEL IN A DIRECTION TOWARD THE VANES OF THE IMPELLER WHEEL TO AN EXTENT AT LEAST OVER HALF BUT LESS THAN THREE QUARTERS OF THE DEPTH OF THE CONCAVE SURFACE CHANNEL AND HAVING A FREE LONGITUDINAL EDGE DISPOSED PARALLEL TO AND SPACED AWAY FROM THE VANES AND SAID RIB BEING SPACED FROM THE SIDE PORTIONS OF THE CONCAVE SURFACE CHANNEL SO THAT THE CONCAVE SURFACE CHANNEL HAS INNER AND OUTER FREE RADIAL ZONES ON OPPOSITE SIDES OF THE RIB.