DE2838200A1 - Split rotor type pump - has auxiliary impeller at delivery end to produce axial thrust to balance impeller thrust - Google Patents

Abstract

The pump has an impeller on the shaft extension of a rotor. The rotor is enclosed by a sleeve and is within the liquid space. A part of the liquid flows to the non pump end through a bore through the rotor and returns through the gap between the rotor and the sleeve. This circulation is established by an auxiliary impeller at the non pump end. The back plate of the auxiliary impeller carries radial blades. A stator plate is fixed close to the outer edge of these. The blades and stator plate produce an axial thrust which balances the axial thrust of the main impeller.

Description

Method for operating a canned motor pump unit or the like. and canned motor pump unit or the like. to carry out of the procedure

The invention relates to a method for operating a branched off Partial flow of the flow having canned motor pump units or the like.

It is known that canned motor pump units have a pump part and a drive motor connected to it via a shaft. The rotor of the drive motor is in one Can space which is essentially enclosed by a can. This results in a gland-free closure of the pump drive shaft including the motor rotor. The side cavities adjoining the can on the face are also in the present case considered to belong to the can space.

The branched off partial flow of the pumped medium flows through the can space between the rotor and the can as well as a further partial flow guide, for example through a V.'ellen longitudinal bore be formed in the common part of the motor and the pump can. The branched off partial flow is used for bearing and motor cooling and also for bearing lubrication,

With the above-mentioned units, considerable axial forces sometimes occur on the impeller or rotor during operation. Main cause of thrust represents the impeller, in multi-stage pumps the rotor set, whereby the thrust of the impeller is generally used for the S / Gu / RH / 2

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Shows pump suction side.

When the partial flow from the pump part flows over the rotor Step on the rotor towards the end of the unit remote from the pump additional thrust forces that oppose the axial forces of the impeller and more or less compensate for them.

However, it is often also useful under certain operating conditions u./od. The conveyed media transfer the branched partial flow in the opposite direction from the end remote from the pump to the pump part to let the rotor flow. In this case, an additional thrust force of the rotor arises in addition to the axial forces of the impeller in the direction of the pump side, which compensates for the total thrust, for example by taking measures on the pump impeller and the like. difficult.

One possible measure for axial thrust compensation is here the so-called relief disc mentioned, which is connected to the shaft and whose flat sides are subjected to different pressures in the sense of an axial thrust compensation. These However, the measure usually requires considerable design effort and, in addition, there is also a loss of delivery.

The object of the invention is therefore first of all to provide a method to operate a canned motor pump unit of the type mentioned, in which the occurring unbalanced Part of the axial thrust is at least largely compensated.

In particular, there should also be an axial thrust compensation for units, whose motor rotor is overflowed from the side remote from the pump, be possible.

To solve this problem, it is proposed according to the invention in particular that that a residual axial thrust of the pump impeller or the like at least largely by generating a counter-axial thrust in the branched off partial flow is compensated.

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The remaining axial thrust that would otherwise arise can thereby be practically dismantled, so that, among other things, complex axial bearings are also required and the like. Can be dispensed with.

It is provided according to a further feature of the invention that with the generation of the Gegen.en-AxialSchubes a pressure difference is created for a secondary circuit of the branched partial flow, which preferably lubricates a shaft bearing remote from the pump and / or. flowing through it for cooling. In other words, this means that a separate secondary circuit is created, which has a pressure gradient which is especially matched to the lubrication and cooling requirements. This ensures, among other things, a good supply of this camp. In particular, however, this can also result in an effective pressure reduction in the area close to the shaft, for example between the bearing diameter and the shaft end _/ , which contributes significantly to the axial thrust compensation.

According to a further proposal of the invention, it is preferable for canned motor pump units of single-stage design, especially for liquid gas j, if the amount of the branched partial flow circulating in the unit of time is essentially independent of the operating state of the pump or its delivery rates and approximately constant over the operating range of the pump, and if, in addition, a residual axial thrust of the pump impeller is at least largely compensated for by generating a counter-axial thrust in the branched off partial flow. This method enables, on the one hand, a cooling and lubrication of the bearings and drive of the unit that is independent of the operating point of the pump, but at the same time enables counter-axial thrust to be generated to compensate for the remaining axial thrust of the pump impeller.

The invention also relates to a split-drum unit Purapen unit or the like, with, among other things, the Mator Botor or the like. containing, by a withdrawn partial flow of the pump delivery flow through which the can space flows, in particular for carrying out the method according to the invention ο This unit is particularly characterized according to the invention in particular "that in the area of the end of the can space remote from the pump a pump impeller-like ₉ in the branched off

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Partial flow working counter-axial thrust generator is provided.

The branched off partial flow is advantageously with The counter-axial thrust generator is used to compensate for the rest of the axial thrust.

In the case of a unit that has an auxiliary pump impeller in the area of the end of the can space remote from the pump for conveying the branched off Has partial flow from the end of this can remote from the pump through the gap in the direction of the pump part it is useful if the counter-axial thrust generator on the auxiliary pump impeller is arranged.

In this embodiment a canned motor pump unit Axial thrust compensation is particularly difficult because here, in addition to the thrust component of the pump impeller, that of the Motor rotor or the like. occurs in the same direction.

However, by means of the counter-axial thrust generator according to the invention in this case, too, a compensation of the axial thrust which has not yet been compensated in any other known way can be created. In addition, the counter-axial thrust generator can be used with little effort due to the arrangement on the auxiliary pump impeller provided here.

An advantageous embodiment of an assembly according to the invention provides that the counter-axial thrust generator on the Pump impeller or the like. A shaft that connects to the motor rotor and is open on one side to the end remote from the pump, a counter-axial thrust impeller has, whose high pressure side with the can space and its low pressure side via bearing gaps or the like. Passages in the case of a shaft bearing remote from the pump, they are connected to a further partial flow of the branched-off partial flow, the flow channels of the counter-axial thrust impeller in the axial direction are covered by a flow guide counter plate.

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The Gegen-Axialscliub impeller has with its open, the Side having flow channels to the end of the unit remote from the pump. The flow guide counter-plate arranged at a short distance from this side has the function of a pump housing with an open impeller. By means of this counter-axial thrust impeller in connection with the "stationary counter-plate" as well as the preferably provided, separate secondary circuit, one can effective axial thrust compensation component can be built up. The counter-axial thrust generator works in the desired manner like an active, pump impeller-like "axial compensation disc".

In the case of a canned motor pump unit that does not have an auxiliary pump impeller has, in particular in an assembly in which the motor rotor is flowed over from the pump side, has Counter-axial thrust impeller expediently one on the shaft non-rotatably seated turntable with several, preferably radially oriented, ribs attached to a flat side.

In a further embodiment of the invention, the number and / or are. the geometric dimensions of the ribs of the counter-axial thrust impeller, the size of the opposing surface of the counter plate and the width of the bearing gap or the like to the intended Axial thrust compensation component can be adjusted, preferably by simple reworking.

The ribs can vary in their radial extent, in their axial width and also in their number according to the requirements be provided.

The flow guide counter-plate is expediently formed by a plate-like flange connected to the stationary part of the bearing remote from the pump, in particular the end shield. _E di counter plate can also be integrally connected to the bearing plate, so that it is equal in its preparation

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is molded with. Additional assembly work can therefore be omitted. There is also a good positional fixation in relation to the counter-axial thrust impeller given.

According to an expedient further development, the shaft is known per se Way as a hollow shaft with an inlet opening on the remote from the pump Formed at the end, where a throttle point there, preferably - is provided by a screw with a throttle hole. By this throttle point can specify the delivery rate of the secondary circuit of the partial flow and thus the thrust behavior can be changed. It is through Changing the throttle point with regard to its throttling effect is a change the axial thrust compensation component possible.

In particular, in a unit with an auxiliary pump impeller it is advantageous if in the area of the impeller space of the Can space or the like separating closure or the like, flow guide channels on the one hand from the pump impeller chamber to the longitudinal bore of the shaft and on the other hand from the pump impeller chamber to the part of the can space near the pump are provided, the Degree or the like, preferably as a bearing plate for the near the pump is used. On the one hand, the entire partial flow is thereby housed within the unit housing and In addition, there is also the advantage that both the partial flow removal and the return of the partial flow guidance essentially result at points of approximately the same, opposite the suction side and possibly also opposite an intermediate stage in the case of multi-stage Pumps, however, are connected to an increased pressure level. The auxiliary pump impeller ensures the flow cycle of the partial flow. This embodiment is particularly useful when promoting Liquids close to their evaporation limit are advantageous.

The following is the invention in its essential details explained in more detail with reference to the drawing.

It shows:

Fig. 1 A partially broken away ^ in longitudinal section

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1 <r 2338200

held side view of an economical engine pump unit,

Fig. 2 shows a section of the end of the pump-remote end of the with an auxiliary

pump gear equipped unit,

Fig. 3 is a view similar to Fig. 2, but here without auxiliary pump

Wheel,

Fig. 4 is an end view of an auxiliary pump impeller with counter

Axial thrust rotorM,

5 shows a counter-axial thrust generator shown approximately on one side

with drawn pressure distribution and

Fig. 6 is a partial longitudinal section of a motor-pump assembly, the

has a magnetic coupling and is equipped with a counter-axial thrust generator according to the invention.

A canned motor pump unit V (Fig. 1) has a pump part 2 'of single-stage design with a pump impeller 3 and a Drive motor 4 on. The pump part 2 and the drive motor 4 ″ have a common shaft 5 which, on the one hand, is the pump impeller 3 and on the other hand the motor rotor 6 carries. It is mounted in bearings 8 on the pump side and at the end 7 remote from the pump.

In the region of the drive motor 4, a gap pipe 9 "which encloses a canned space 10 and the motor rotor 6 tight in relation to the other parts of the drive motor 4, seals especially against the stator 11 can be seen.

The motor rotor 6 is located within the can space 10 ′ and also the camp 8. With this embodiment of the unit with a can 9, the pump drive is terminated without a stuffing box sxvel Ie including the motor rotor was created.

For cooling and lubrication purposes, a partial flow branched off from the conveying medium flows through the can space 10. To feed this branched off partial flow serves a trowel longitudinal bore 12 the at the inflow end on the pump side via transverse bores 13 and an annular space 14 with the pressure side of the guide spiral 15 of the pump

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housing is connected. At the end T remote from the pump, this branched off partial flow again enters an auxiliary pump impeller 16 via transverse bores 13a. This branched off partial flow then flows over the motor rotor between this and the can 9 and finally reaches the impeller space 17 * again.

Occurs during operation of the unit, on the one hand caused by the pump impeller 3 ', and in the present case additionally also by the overflow of the motor rotor 6 by the branched off Partial flow, an axial thrust in the direction of arrow Pf 1.

In addition to known axial thrust compensation not shown here in detail facilities has the canned motor pump unit according to the invention 1 in the area of the end 7 of the can space 10 remote from the pump, a pump impeller-like, in the branched off partial flow working counter-axial thrust generator 18 on. This is essentially by a counter-axial thrust impeller 19 seated on the shaft 5 and open on one side toward the end 7 ″ remote from the pump formed that with a flow guide counter-plate 20 cooperates. This counter plate 20, which is arranged at a small distance from the open side of the counter axial thrust impeller 19 is, practically has the function of a pump housing with an open impeller. The counter plate 20 is rigid connected to the unit housing.

In the preferred embodiment of a canned motor pump unit 1 according to the invention shown in FIGS. 1 ″ and 2 ′ , the counter-axial thrust generator 18 is arranged on the auxiliary pump impeller 16. For this purpose, on the rear side 21 of the auxiliary pump impeller 16 facing the end 7 remote from the pump, approximately radially oriented Ribs 22 attached (see also Fig. 4). In the embodiment, the counter-axial thrust impeller 19, which here also represents a part of the auxiliary pump impeller 16, has six ribs 22. It can also be seen that the radial extension

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this rib is smaller than that of the impeller rear side 21 and also smaller than the radial extension of the axial delivery channels 23 of the auxiliary pump impeller 16.

The counter-axial thrust with the help of the counter-axial thrust generator 18 is now structured as follows:

The branched off through the Trowel longitudinal bore 12 in its suction side area reaching partial flow promoted. There is a canned space near the auxiliary pump impeller accordingly, the pressure generated by the auxiliary pump impeller 16. This causes a secondary fluid circuit via the counter-axial thrust impeller 19 and the motor-side bearing 8 and through the rear end of the longitudinal shaft bore 12 back to Suction side of the auxiliary pump impeller. The driving pressure for this The secondary circuit is formed by the differential pressure between the auxiliary pump impeller 16 and the counter-axial thrust impeller 19.

5 clearly shows from the pressure distribution diagram drawn in that the pressure reduction on the side of the counter-axial thrust generator 18 facing the end 7 remote from the pump takes place in two stages. The coordinate axes of the pressure distribution diagram are identified by the arrows Pf 4 and Pf 5, the arrow Pf 4 indicating the change in pressure and the arrow Pf 5 indicating the distance from the longitudinal axis L. On the side of the counter-axial thrust generator 18 facing the can space 10, there is a pressure distribution according to the curve K .., the prevailing pressure being almost constant up to the shaft 5 or only decreasing slightly. In contrast, the opposite pressure prevailing on the other side of the counter-axial thrust generator 18 towards the shaft 5 decreases significantly more (KuTVeK ₂ ). This results in a resulting pressure component in the direction of arrow Pf 2, which counteracts the axial thrust (arrow Pf 1). The intended secondary circuit with the throttle point 31 now takes place in one

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Stage rait subsequent gradual decrease in pressure Another pressure reduction on the side facing the end 7 remote from the pump. This is shown by the curve JC3. The reduction in pressure takes place here as a result of the throttling effect of the bearing gap, provided that the shaft bore is dimensioned so large that no additional throttling effect of wave 5 occurs. Without this separate secondary ice run, the dashed line pressure distribution would result (Curve K4). This would mean a higher application of pressure given the circular ring surface 34 of the "shaft end face and thus a reduction in the counter-axial thrust component (Pf * 2). On the other hand, according to curve K3, which occurs when a secondary circuit is provided, an effective pressure relief of the shaft end created. By changing the throttle bore 33 of the throttle point, the counter-axial thrust can be changed within certain limits, because this reduces the pressure on the engine-side Shaft end (circular ring surface 34) can be varied. The bore 33 should for effective relief of the shaft end be as big as possible.

It should be mentioned again that the intended secondary circuit In addition to the lubrication and cooling function for the bearing, it is essential for the creation of the counter-axial thrust contributes. All the more so since the ribs 22 on the counter-axial thrust impeller 19 often only attached to the outer diameter area of the counter-axial thrust impeller 19 for reasons of space can be.

It should also be mentioned that the pressure reduction according to curve K2 also takes place without a separate secondary circuit via the motor-side bearing 8.

Briefly summarized, this results in the counter-axial thrust force according to arrow Pf 2 in Fig. 2 and 5 from the to the front

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Cover disk 24 of the auxiliary pump impeller 15 acting, generated by the auxiliary pump impeller 16 and the pressure generated on the back 21 of the auxiliary pump impeller or the counter-axial thrust impeller 19 acting pressure forces. From this it follows there is a differential pressure as counter-axial thrust in the direction of arrow Pf 2.

As already made clear above, the high pressure side 25 of the counter-axial thrust impeller 19 is with the can space 10 and its low pressure side 26 or the like via bearing gaps. Entrances, e.g. also the throttle stele 31 on the one remote from the pump Shaft bearing 8 is connected to the longitudinal shaft bore 12. The secondary circuit flows through from the Coming on the pressure side of the auxiliary pump impeller 16, the area of the counter-axial thrust impeller 19, the bearing gap and then occurs into the shaft bore 12. From there it reaches the suction area of the auxiliary pump impeller 16 and is then again promoted to its print side.

Fig. 3 shows a section of a somewhat modified, according to the invention Canned motor pump unit 1, in which the flow circuit of the branched off partial flow compared to that in Fig. 1 'and 2 shown is provided reversed. The motor rotor 6 is flowed over in the direction of the end 7 remote from the pump. This will a counter-axial thrust already built up to a certain extent, which opposes the axial thrust generated by the pump impeller. Of the The branched off partial flow is after the overflow of the motor rotor

6 passed into the longitudinal shaft bore 12 via transverse bore 13a. In the present case, no auxiliary pump impeller is provided. However, by appropriate selection of the connection and the outlet for the branched off partial flow in the area of the pump, the desired circulation can also be achieved here. ■

The counter-axial thrust impeller 19 is between the motor rotor 6 and the bearing 8 remote from the pump. It is essentially 'by a turntable 27 which is seated non-rotatably on the shaft 5 with several on its in functional position, the end remote from the pump

7 facing flat side attached ^ radially oriented ribs 22 formed.

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The flow guide counter-plate 20 can be replaced by a plate-like, with the fixed part of the bearing remote from the pump, in particular the flange 29 connected to the end shield 28 may be formed.

As already mentioned and as shown in Figure 4 ', the ribs 22 have a somewhat reduced radial extent. In adaptation to the desired pressure conditions, the Number and / or the geometric dimensions of the ribs can be matched to the intended axial thrust compensation component. Even by the size of the surface of the counter plate 2o opposite these ribs and the width of the bearing gap and the like influencing the pressure conditions is possible. Also by changing the throttle point 31, such an influence is as already mentioned, possible.

1 to 4 clearly show that the throttle point 31 is provided at the inlet opening 30 of the hollow shaft 5. This is formed by a screw 32 screwed into the longitudinal shaft bore 12 with an axial throttle bore 33. By the dimensioning of the throttle bore 33, the counter-axial thrust can be influenced.

The flow guidance of the branched off partial flow, which can be seen in FIG. 1, in particular the removal and the return of this partial flow at points of approximately the same pressure and also overall increased pressure level has the advantage that it is also close to their evaporation limit horizontal media can be conveyed without any problems. The overall increased pressure level of the partial flow increases namely in an advantageous manner on the temperature side the distance of the partial flow medium from its evaporation limit. Farther it is advantageous that the branched off partial flow and the pressure conditions even with major changes in the delivery conditions the pump remain essentially constant, so that even when pumping in the vicinity of their

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Liquids lying at the evaporation limit are approximately uniformly favorable.

The canned motor pump assembly according to the invention thus combines the advantage of an approximately constant, partial flow circuit with the advantages of an effective axial thrust compensation .

It should also be mentioned that under canned motor pump units or the like. also those with a magnetic coupling (so-called. Magnetic pumps).

Such a motor-pump 1a is shown in FIG. 6. One can be seen here between the drive motor 4 and the pump part 2 provided magnetic coupling 35. The inner coupling part 36 is enclosed by a can 9a. Outside of of the can 9a is the outer, pot-shaped one Coupling part 37 can be seen, which comprises the can 9 a and the coupling part 36 located therein. The coupling part In terms of its function, 36 corresponds approximately to the motor tube 6, e.g. according to Fig. 1. The counter-axial thrust generator 18a (Fig. 6) is arranged approximately the same as that in Fig. 1 and functions in the same way.

All in the description, the. Claims and the drawing Features shown can be essential to the invention both individually and in any combination with one another be.

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Claims (1)

Claims Method for operating a branched off partial flow of the Canned motor pump units or the like having the conveying medium, characterized in that a residual axial thrust of the pump impeller (3) or the like, at least largely compensated for by generating a counter-axial thrust in the branched off partial flow will. 2. The method according to claim T, characterized in that with the generation of the counter-axial thrust created a pressure difference for a secondary circuit of the branched off partial flow which preferably flows through a shaft bearing remote from the pump in a lubricating and / or cooling manner. 3. The method according to claim | or 2 _s, preferably for canned motor pump units of single-stage design ^, especially for liquid gasj, characterized by the combination that "- .. a) the amount of the branched-off partial flow circulating in the unit of time is essentially independent of the operating state of the pump or its delivery rate and approximately constant over the operating range of the pump is _a and that b) a residual axial thrust of the pump impeller, at least largely is compensated by generating a counter-axial thrust in the branched off partial flow. 4 * canned motor pump unit or the like. with one of the Motor rotor, containing, from a branched off partial flow of the Θ3001 1/0331 ⁿ - Pump delivery flow through which the can space flows, in particular for carrying out the method according to claims 1 to 3 ', characterized in that in the area of the end remote from the pump (7) of the can space (10) a pump impeller axtiger, in the branched off Partial flow working counter-axial thrust generator (18) is provided. 5. Unit according to claim 4, which is in the area of the pump remote At the end of the canned space there is an auxiliary pump impeller for pumping of the branched off partial flow from the end of this canned space away from the pump through the space in the direction of the pump part has out, characterized in that the counter-axial thrust generator (18) is arranged on the auxiliary pump impeller (16). 6. Unit according to claim 4 or 5, characterized in that the Counter-axial thrust generator (18) is a one-sided shaft (5) that connects the pump impeller (3) or the like to the motor rotor (6) to the end remote from the pump (7) open counter-axial thrust impeller (19) has its high pressure side (25) with the can space (10) and its low pressure side (26) via bearing gaps or the like. Passages in a shaft bearing (8) remote from the pump with a further partial flow of the branched off partial flow is in communication, and that the flow channels of the counter-axial thrust impeller (19) in ″ axial direction through a flow guide counter plate (20) are covered " 7. Unit according to one or more of claims 4 to 6, characterized characterized in that the counter-axial thrust impeller (19) a turntable (27) which is seated non-rotatably on the shaft (5) and has several preferential prices attached to one flat side has radially oriented ribs (22) » _s in ο unit according to one or more of the preceding claims characterized in that the number "/ od. and.. the geometric dimensions of the ribs (23) of the counter-thrust-impeller (19), the size of this opposing surface of the counterplate ( 20) the throttle point {31) and the width of the bearing column etc. / 3 © 300 11/0337 on the intended. Axial thrust compensation component can be adjusted are, preferably by simple reworking. 9. Unit according to one or more of claims 4 to δ thereby characterized in that the flow guide counter plate (20) by a plate-like, with the fixed part of the pump-remote bearing (8), in particular with the end shield (28) connected flange (29) is formed. 10. Unit according to one or more of claims 4 to 9, characterized characterized in that the shaft (5) is designed as a hollow shaft with an inlet opening (30) at the end (7) remote from the pump, a throttle point (31) being provided there, vzw. by a screw (32) with a throttle bore (33). 11. Unit according to one or more of the preceding claims, characterized in that in the area of the de.n impeller space (17) from the can space (10) or the like separating closure or the like, Flow guide channels on the one hand from the pump impeller chamber (17) to the shaft longitudinal bore (12) of the shaft (5) and on the other hand are provided from the pump impeller space (17) to the part of the can space (10) close to the pump, and that the conclusion or the like. vzw. serves as a bearing plate (28a) for the bearing (8) close to the pump. -Patent attorney- 0300 11/033 7