EP0170175B1 - Regenerative pump with force balancing - Google Patents

Abstract

The present invention relates to a regenerative pump having a casing with a casing inlet and casing outlet, an impeller disposed on a shaft and containing at least one bucket ring with axially and radially open bucket compartments on the first and second side of the impeller, and mutually separated side channels having an entrance port, an exit port and an interrupter. The arrangement herein is such that the conveying streams on the two sides of the impeller are separated from each other. The entrance ports of the side channels on the two impeller sides are in communication with the casing inlet, and the exit ports are in communication with the casing outlet, so that the conveying streams are first subdivided and then recombined. The entrance port, the exit port, and the interrupter in opposition to the first impeller side are arranged to be offset in the direction of rotation of the impeller by such an angular amount with respect to the corresponding elements on the second impeller side that the radial forces on the first impeller side, resulting from the pressure differences in the conveying streams between the inlets and the outlets, are counterbalanced by radial forces on the second impeller side that are the same with respect to amount but are effective in the opposite direction. In this way, compensation of the radial forces acting on the pump shaft is attained.

Description

The invention relates to a side channel pump with a housing with a housing inlet and a housing outlet, in which the radial forces generally acting on the impeller shaft in side channel pumps are compensated, so that the pump is suitable for generating high and very high pressures.

As is known, multi-stage side channel pumps are particularly well suited for achieving high pressures with relatively low flow rates. Multi-stage side channel pumps are particularly easy to set up if only one impeller is used which has a plurality of differently sized vane cell rings with relatively short blades on each side of the impeller. Usually, the blade cells arranged on the outer circumference are separated from one another in the axial direction by a central web and work in a common side channel. Since the pressure in the pumped medium increases steadily from the inlet of the side channel to its outlet in the running direction, the resultant force component in the radial direction results from the pressure acting on the impeller. This radial force takes on considerable dimensions at high delivery pressures. In the case of high-pressure pumps of this type, reinforced shafts and also reinforced bearings must consequently be provided, which entails considerable additional costs, in particular for the shaft seals, and also leads to an undesirably large diameter of the first impeller inside the impeller.

From DE-OS 21 05 121 a side channel pump is known, in which pressure pockets are arranged in the housing in order to compensate for these radial forces are connected to the suction and pressure sides of the pump. The arrangement of the pressure pockets and the connecting lines is such that the pressure prevailing in the pressure pockets acts on a special part of the impeller provided for this purpose in such a way that the forces acting radially inward on the impeller are compensated for by the pumping process. However, this solution requires additional regulating elements in the connecting lines in order to match the pressure conditions built up in the pressure pockets to the respective delivery head or the delivery pressure of the pump. In addition, with this arrangement, a short circuit of the pump leading to leakage losses is accepted, which leads to a flow of the conveyed medium from the pressure side via the throttle gap of the pressure pockets to the suction side. These losses significantly reduce the hydraulic efficiency of the pump, especially with small volume flows.

From DE-OS 31 28 374 a side channel pump is known, the impeller of which has a blade ring with closed blade cells on each side, separate side channels being arranged opposite these blade rings, each having an inlet opening and an outlet opening and an interrupter. The pumped medium flows in this pump in two separate feed streams via the side channels from the respective side channel inlet to the respective side channel outlet. However, the radial forces mentioned at the outset also occur in this pump.

From US Pat. No. 2,662,479 a single-stage turbine pump provided with side channels is known, in which a force equalization is achieved by dividing the working channel into two ring halves, which are arranged opposite one another (at a distance of approximately 180 °), both of which are provided by supply channels the intake and on the discharge side are connected to the discharge port of the pump by channels. In this way, a balance of forces is achieved, but for the price of a greatly reduced pressure increase compared to a pump of the same size, in which the working channel is not interrupted.

From US Pat. Nos. 2,574,724 and 1,979,621, two-rotor side channel pumps are known in each case, in which the channels of one rotor are offset in the circumferential direction in relation to those of the other rotor in such a way that there is a radial force compensation between the rotors. In both cases, they are single-stage, double-flow pump units. The two-stage process results from the axial series connection of two separate rotors with assigned working channels.

Based on the above-mentioned prior art, the present invention has for its object to improve a single-rotor high-pressure side channel pump so that the shaft of the impeller essentially only has to transmit or absorb torques.

This object is achieved by a side channel pump with a housing with a housing inlet and a housing outlet, with an impeller on a shaft, with at least one blade ring with radially and axially open blade cells on the first and on the second side of the impeller, with side channels separated from one another by sealing gaps , each with inlet opening, outlet opening and interrupter, the inlet openings being connected to the housing inlet and the outlet opening being connected to the housing outlet for dividing and reuniting the conveying flows, and the side channels being arranged opposite the blade rings in such a way that a conveying medium is in two essentially from one another separate flow flows through the side channels from the respective side channel inlet to the respective side channel outlet with increasing pressure,
which is characterized in that the inlet openings, the outlet openings and the breaker (s) of the first impeller side are (are) offset in the circumferential direction of the impeller by 180 ° to the corresponding elements of the other impeller side, that the two impeller sides and the associated side channels in the are essentially identically shaped so that each side channel extends essentially over the entire circumference of the respective pump stage, so that the beginning and end of the side channel of a stage are only separated by the short interrupter,
that an axial final stage sealing gap for the sealing separation of the two flow rates is arranged on the outer circumference of the impeller,
and
that at least two vane cell rings with different diameters are arranged on at least one impeller side, the respective side channels of which are connected in series.

This measure, which can be represented very easily in terms of construction, compensates for the inevitable radial forces already in the impeller, so that no more radial forces act on the shaft of the impeller. In this way, on the one hand, the bearing of the shaft with the associated seal can be made smaller in a cost-effective manner without reducing the service life of the pump. In addition, the smaller dimensions of the impeller shaft mean that an inner blade ring with a small diameter and correspondingly low peripheral speed can be provided during operation. Because the peripheral speed is low, the efficiency-reducing acceleration impact on the medium is reduced when entering the pump.

Furthermore, the arrangement according to the invention makes it possible to mount a large number of blade rings of different diameters with corresponding side channels, that is to say a large number of pumping elements connected in series, on a single impeller, which is because of the previously radial forces occurring was not possible and was avoided by dividing the pressure stages over several separately mounted impellers.

The solution according to the invention results in a further advantage in multi-stage impellers in that the individual blade rings can each be constructed with axially and radially open blade cells, the sealing between the conveying stages being effected by radial sealing gaps, so that the blade cell rings are at the theoretical minimum distances can be graduated. This minimum gradation in turn reduces the above-described acceleration impact on the conveying medium from the entry of the one into the subsequent stage with its disadvantageous effects. This option has also not been able to be used so far, since this construction results in very wide impellers which lead to undesirably large bearing distances.

In the present side channel pump, the two impeller and side channel sides, which are separated from one another in a sealing manner, have an inverse effect, i.e. the respective pressure build-up along the side channel circumference of one side is offset by 180 ° about the shaft axis, i.e. opposite to the other side channel side. Thus, radial forces of equal magnitude are juxtaposed at each point on the side channel circumference, so that the radial forces which arise on both sides of the impeller are automatically compensated for without loss and without additional devices at each operating point of the pump.

Due to the radial force-free construction of the pump, the otherwise occurring vibrations of the shaft due to its deflection are avoided, so that the service life of the pump is further increased.

The overturning moment, which is generated by the opposite axial forces on the two impeller sides, runs opposite to the overturning moment, which acts on the two wheel sides due to the radial forces. If the depth of the impeller is dimensioned accordingly, torque can be equalized and thus an essentially force-free shaft (except for the torques).

Figur 1

einen Längsschnitt durch eine bevorzugte Ausführungsform der erfindungsgemäßen Seitenkanalpumpe entlang der Linie I-I aus Fig. 2,

Figur 2

eine Ansicht in Pfeilrichtung (A) der Seitenkanalpumpe nach Fig. 1 mit abgenommenem stirnseitigen Gehäusedeckel,

Figur 3

eine Aufsicht auf das Laufrad aus Fig.1 und 2,

Figur 4

einen Schnitt entlang der Linie II-II aus Fig. 3,

Figur 5

einen Schnitt entlang der Linie IV-IV aus Fig. 6, des ersten Seitenkanalteiles aus Fig. 1 mit strichpunktiert eingezeichnetem Laufrad,

Figur 6

einen Schnitt entlang der Linie III-III aus Fig. 5,

Figur 7

einen Schnitt entlang der Linie VI-VI aus Fig. 8 des zweiten Seitenkanalteiles aus Fig. 1 mit strichpunktiert eingezeichnetem Laufrad,

Figur 8

einen Schnitt entlang der Linie V-V aus Fig. 7,

Figur 9

einen Halbschnitt durch eine weitere bevorzugte Ausführungsform eines Laufrades mit Schaufelzellenkränzen und strichpunktiert angedeuteten Seitenkanälen und mit axialen Endstufen-Dichtspalten zur Trennung der Förderströme und mit axialen Zwischenstufenspalten, und

Figur 10

einen Halbschnitt durch eine weitere bevorzugte Ausführungsform eines Laufrades mit Schaufelzellenkränzen mit strichpunktiert angedeuteten Seitenkanälen und radialen Endstufen-Dichtspalten am äußeren Umfang und radialen Zwischenstufendichtspalten.

Exemplary embodiments of preferred embodiments of the invention are explained in more detail below with the aid of figures. Here shows

Figure 1

2 shows a longitudinal section through a preferred embodiment of the side channel pump according to the invention along the line II from FIG. 2,

Figure 2

2 a view in the direction of the arrow (A) of the side channel pump according to FIG. 1 with the front cover removed,

Figure 3

a top view of the impeller from Fig. 1 and 2,

Figure 4

4 shows a section along the line II-II from FIG. 3,

Figure 5

6 shows a section along the line IV-IV from FIG. 6, the first side channel part from FIG. 1, with the impeller shown in broken lines,

Figure 6

4 shows a section along the line III-III from FIG. 5,

Figure 7

8 shows a section along the line VI-VI from FIG. 8 of the second side channel part from FIG. 1 with the impeller shown in broken lines,

Figure 8

7 shows a section along the line VV from FIG. 7,

Figure 9

a half section through a further preferred embodiment of an impeller with vane cell rings and side channels indicated by dash-dotted lines and with axial final stage sealing gaps for separating the flow rates and with axial intermediate stage gaps, and

Figure 10

a half-section through a further preferred embodiment of an impeller with vane cell rings with side channels indicated by dash-dotted lines and radial final stage sealing gaps on the outer circumference and radial intermediate stage sealing gaps.

The preferred embodiment of the pump shown in FIGS. 1 to 8 shows a two-stage, double-flow side channel pump with a radial final stage sealing gap 36 and consists of a housing 10 and an impeller 30. The housing 10 is constructed in several parts and consists of a housing ring 11 with a housing inlet opening 12 and outlet opening 13 (Fig. 2), an end housing cover 14, a drive-side bearing cover 15 and the two side channel parts 16 and 16 '.

In the side channel parts 16 and 16 ', the side channels 17 and 17' are arranged with side channel inlet openings 18 and 18 ', side channel outlet openings 19 and 19', transfer channels 21 and 21 ', and the side channel breakers 20 and 20'.

The housing cover 14 and the bearing cover 15 are sealed in the housing ring 11 by round cord rings 24 and screwed to the housing ring 11 with housing screws 26 (indicated by center lines). The side channel parts 16 and 16 ′ arranged in the housing 10 are sealed off from one another by a round cord ring 25 and are fixed in the axial direction by the housing cover 14 and bearing cover 15. In the bearing cover 15 of the housing 10, a shaft 28, which is sealed by packing rings 27, is mounted, which is set in rotation in the direction of the arrow (FIG. 2) by a drive motor, not shown, for example an electric motor. The impeller 30 is fastened to the free end of the shaft 28 by means of a feather key 29.

The two-stage impeller 30 has blade cell rings 31, 31a on its first side, and blade cell rings 31 ', 31'a on its second side, which are formed from radially and axially open blade cells 32, 32a and 32', 32'a, respectively.

The conveying medium entering through the housing inlet opening 12 of the housing 10 divides in a distribution channel 23, which is incorporated into the housing 10, into two conveying streams which are separated into the side channel inlet openings 18 and 18 'via feed channels 37, 38 in the side channel parts 16 and 16'. reach. Here are the Side channel inlet openings 18 on one side of the impeller are offset by 180 ° about the shaft axis to the side channel inlet openings 18 'on the other side of the impeller. The conveying medium entering the side channels 17, 17 'of the first stage reaches the blade cells 32, 32' of the blade cell rings 31, 31 'of the rotating impeller 30. In the blade cells 32 and 32', centrifugal forces form displacer flows, each in flow in a helically wound current path over the entire length of the side channels and alternately reenter the blade cells 32 and 32 'of the impeller 30. As a result of this constant re-entry, energy of the blade cells 32, 32 'of the impeller 30 is transferred to the lower flow energy flow (pressure, speed), which flows more slowly in the side channel.

At the end of the side channels 17, 17 ', the conveyed medium enters the side channels 17a and 17'a of the second stage via transfer channels 21, 21', where the blade cell rings 31a and 31'a of the impeller 30 enter via the blade cells 32a and 32'a further pulse exchange, as described above for the first stage, takes place. After this further supply of energy, the conveyed medium passes via the side channel outlets 19 and 19 'in the side channel parts 16 and 16' into a feed channel 22 in the housing 10 and from there out of the housing through the outlet opening 13.

The pressure build-up in the side channels 17 and 17a of the side channel part 16 takes place inversely due to the angular offset (by 180 °) to the side channel part 16 'with side channels 17' and 17'a. This means that at any point on the circumference of the side channels 17 and 17a of the side channel part 16 in radial force acting on the shaft counteracts an amount of equal magnitude counterforce from each point of the circumference of the side channels 17 'and 17'a of the side channel part 16'.

The two impeller outer rings 31a and 31'a on the outside of the impeller are separated from one another by a relatively wide web, which thus forms a cylindrical outer surface of the impeller. The two side channel parts 16, 16 'together form an equally wide "web" between the two outer side channels 17a, 17'a, so that the two flow rates of the output stages are sealed from one another via a radial output stage sealing gap 36. In this embodiment, the sealing between the steps on the respective impeller sides takes place by means of axial intermediate step sealing gaps 33, 33.

With appropriate selection or calculation of the radial and axial dimensions of the blade rings, not only the radial forces acting on the shaft are compensated, but also the torques caused by them around the center of the impeller, which causes it to tip on the shaft, since the impeller in Forces acting in the axial direction produce a torque opposite to the first-mentioned torque.

In FIGS. 9 and 10, only half cross-sections through impellers of further preferred embodiments are shown, the associated side channel parts having side channels, overflow channels, sealing gaps, etc. being designed in accordance with the embodiment described above, unless otherwise stated.

In the embodiment according to FIG. 9, vane cell rings 31, 31a, 31b are arranged on one side of the impeller and vane cell rings 31 ', 31'a and 31'b are arranged on the other side, which side channels (indicated by dash-dotted lines) 17, 17a, 17b and 17 ', 17'a, 17'b are opposite. The separating seal between the output stages 17b, 17'b on the two impeller sides takes place via axial output stage sealing gaps 34 and 34 ', which are arranged between the impeller 30 and the side channel parts 16, 16'.

In the further preferred embodiment of the side channel pump shown in FIG. 10, the delivery flows are sealed both from stage to stage and from the two output stages to one another via radial sealing gaps 35, 35a, 35 ', 35'a and 36. In this impeller, the diameters increase the blade cell rings only by the minimum possible amount, since the sealing from step to step is carried out essentially exclusively by radial gaps. The fact that the peripheral speed of the blade cells only increases by a small amount from stage to stage results in only a small acceleration shock which reduces the efficiency of the pump when the conveying medium enters the next side channel. In this way it is possible to connect a relatively large number of stages in a side channel pump with a single impeller, so that high pressures can be achieved despite the low construction costs (few parts, low installation costs). Such wide impellers, which result from such a construction, could not be used until now because the impeller width caused an undesirably large distance between the two shaft bearings.

Claims (4)

1. Lateral channel pump having a housing with housing inlet and housing outlet,
   having an impeller on a shaft,
   having at least one bucket ring with radially and axially open bucket compartments on the first and second sides of the impeller,
   with lateral channels separated from one another by sealing gaps, each channel having an inlet port, outlet port and break, the inlet ports being connected to the housing inlet and the outlet ports to the housing outlet in order to divide and reunite the delivery currents, the lateral channels being arranged opposite the bucket rings in such a way that a flow medium flows in two substantially separate currents through the lateral channels from the respective lateral channel inlet to the respective lateral channel outlet whilst the pressure increases, characterised in that the inlet port(s) (18), the outlet port(s) (19) and the break(s) (20,20a) on the first side of the impeller are offset relative to the corresponding elements (18',19',20',20'a) on the other side of the impeller by an angle of 180° in the direction of rotation of the impeller, in that the two sides of the impeller and the associated lateral channels (17,17a,17b; 17',17'a,17'b) are substantially identical in shape, in that each lateral channel extends substantially over the entire periphery of the respective pump stage, so that the start and finish of the lateral channel of a stage are separated only by the short break (20,20a), in that an axial end stage sealing gap (34,34') is provided on the outer circumference of the impeller (30) in order to separate the two delivery currents in sealed manner, and in that, on at least one side of the impeller, there are at least two bucket rings (31,31a,31b; 31',31'a,31'b) of different diameters, the lateral channels (17,17a,17b; 17',17'a,17'b) of which are connected in series.
2. Lateral channel pump according to claim 1, characterised in that radial intermediate-stage sealing gaps (35,35') are provided in order to form a seal between the bucket rings (31,31') of different diameters of the impeller (30) and the lateral channels (17,17') incorporated in lateral channel sections (16,16').
3. Lateral channel pump according to claim 2, characterised in that axial intermediate-stage sealing gaps (33,33') are provided in order to form a seal between the bucket rings (31,31') of different diameters of the impeller (30) and the lateral channels (17,17') incorporated in the lateral channel sections (16,16').
4. Lateral channel pump according to one of the preceding claims, characterised in that the bucket rings (31,31a,31b; 31',31'a,31'b) and the associated lateral channels (17,17a,17b; 17',17'a,17'b) are of such dimensions, with respect to the effective surface areas of the pressure of delivery current on the impeller, that the moments about the centre of the impeller resulting from the axial and radial forces cancel each other out.

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