EP1347178B1 - Easily cleanable centrifugal pump - Google Patents

Abstract

Centrifugal pump comprises a pump housing having a pump chamber (20) with a suction region (26) and a pushing region (27), a running wheel (4) which rotates about a running wheel axis (18) within the pump chamber, and a running wheel drive consisting of a reluctance motor. The motor has an electrical contact-less rotor (5) magnetically arranged within the pump chamber and a stator arranged on or in the housing section (3) of the pump surrounding the rotor. Preferred Features: The rotor is magnetically arranged in the radial as well as in the axial direction in the pump chamber. The running wheel is coupled directly with the rotor.

Description

The present invention relates to centrifugal pump with a pump housing, which has a pump chamber comprising at least one of a suction area and an ejection area Impeller, which is rotatably mounted within the pump space about a wheel axis, and with an impeller drive, wherein the impeller drive consists of two reluctance motors, their stators at or in which the rotor surrounding housing portion of the pump are arranged.

Corresponding centrifugal pumps have been known in numerous variants for a long time. These Pumps are often used for pumping liquids in the chemical industry and also in the food industry. These applications often require one Avoid contamination of the pumping medium. Such contamination can either be caused by it occur that with the pump alternately different media are pumped, so that when pumping a new medium remains of the old medium in the pump available were, although possibly in the meantime a flushing medium was pumped, or in that a pumping process has been interrupted for a long time and in the pump or the Supply lines still remaining medium undergoes an aging process, for example by contact with atmospheric oxygen or simply due to inherent instability. This applies, for example in the case of foods containing only a small number of germs when fresh However, the germ count can increase dramatically if the medium for a long time at a Temperature above 0 ° C is left to itself.

Although contamination is not always dangerous or causes significant deterioration the pumped media leads, it is still desirable to use a centrifugal pump which is very easy to clean and in which e.g. by briefly pumping a flushing medium a previously existing in the pump pumping medium can be completely removed to Contamination of later pumped media to avoid, with the rinsing process as possible quick and easy and without disassembly and without using excessive amounts of Dishwashing agent should take place.

Conventional centrifugal pumps can meet these requirements only with considerable technical Effort to meet. Solution approaches to the design of pumps, a simple and fast Allow cleaning and therefore, e.g. Also suitable as so-called "sterile pumps" and Thus, meet the required in the food and medical sterilization conditions are known from German Patent Application Nos. 100 33 402.4 and 102 00 579.6.

Even if attempts have been made in these known pumps, the design effort so Keep as small as possible while avoiding dead spaces and so the sterility conditions too meet these pumps basically have the problem that the drive shaft for one or several impellers of the pump sealed in any way connected to a motor drive must become. Although you can appropriate seals, e.g. as sliding seals form what because of the mutually moving surfaces of a sliding seal causes between the Sealing surfaces entering pumping medium is also very quickly and easily replaced, however is the production and maintenance of appropriate seals relatively expensive and they also have only a limited life.

The documents WO 96/31 934, US-6,053,705 and EP-1 114 648 A2 show centrifugal pumps each with a reluctance motor, wherein the rotor of the motor and the impeller of the pump are integrated and represent a single, specially designed component. These known from the prior art Centrifugal pumps have in common that they do not allow the hydraulic components to build the pump in a modular manner and without the specifications of the function of the rotor to construct.

Compared to this prior art, the present invention has the object, a To provide centrifugal pump with the features mentioned, which is even easier and is easier to clean and which is therefore particularly suitable for sterile applications or in general for applications where simplified purging and cleaning of a pump is desired is.

According to the present invention, this object is achieved in that the impeller drive of Pump consists of at least one reluctance motor whose electrically non-contact rotor in the Recorded by the pumping medium volume of the pump chamber is received, and its stator is arranged on or in a surrounding the rotor housing portion of the pump.

Such a reluctance motor has traditionally been used for centrifugal pumps Drives have the advantage that the rotor must have neither permanent magnets nor any contains electrical windings that require a power supply. Furthermore, the rotors contain no permanent magnets.

This gives a rotor, e.g. can be connected directly to an impeller and the can rotate together with the impeller in the pump room. Here is under "pump room" one Centrifugal pump the entire existing between an inlet port and an outlet and understood space acted upon by the medium to be pumped. This space is insofar conceptual to distinguish from the space of a pumping cell, the volume within a pumping room limited, which is fully or largely acted upon by a rotating impeller.

Characterized in that the drive rotor no mechanical or electrical connection to other drive elements needed, you do not need any seals for appropriate transitions. The rotor can be connected directly to the driven impeller and both parts in common can be arranged in the pump room so that easy cleaning and rinsing these parts is easily possible.

It is particularly useful if the rotor is independent of the magnetic drive forces has a magnetic bearing. Such storage ensures that the rotor is in Operation of the pump does not come into contact with the pump housing, so that without appropriate Friction even higher speeds are possible. However, the invention would also be readily available one or more sliding bearings open on both sides can be realized, which are easy to flush through and to are clean, since such bearings need not have a sealing function. The magnetic storage is only possible or at least considerably facilitated by the fact that the rotor of the reluctance motor contains no permanent magnets for the drive, but only soft magnetic material.

Conveniently, moreover, the rotor is coupled directly to the impeller, so that no Transmission elements are present, in which parts of the pumping medium could get caught.

In the preferred embodiment of the invention, the rotor is a ring, which with a corresponding Drive shaft is connected, with gaps between radial projections of the Ringes are either filled with non-magnetic material or wrapped around the ring as a whole is, so that the gaps are covered.

The rotors of reluctance motors typically have radial projections of the teeth type a gear on, at different times by magnetic induction of a each nearest pole piece are tightened, according to the desired speed the rotor takes place a fast switching between several poles of the stator. Around despite the necessary radial projections of the rotor as smooth as possible surface to obtained, the design is as a substantially smooth ring with filled interdental spaces or a continuous enclosure preferred.

Furthermore, along the peripheral surface of the rotor, along those surfaces, the an inner housing surface opposite, provided pad cams, which in the case of Rotor standstill on corresponding housing surfaces rest and in the case of a Contact with the housing during rotation take over the function of sliding elements. In the preferred embodiment of the invention, these support cams are annular Webs, preferably on the outer cylindrical surface of the annular rotor and optionally also on one or both axial end faces of the rotor. Conveniently, the material of these casserole cams or webs is chosen so that it has the lowest possible sliding friction with the inner surface of the pump chamber housing has. Particularly preferred is an embodiment the invention in which two reluctance motors are provided for the drive, wherein each one rotor axially in front of an impeller or a group of successively connected wheels, and a rotor behind the impeller or group of cascaded impellers is arranged. Conveniently, the rotors are in the vicinity of the intake and the discharge area of the pump. To have the most balanced radial forces, so that the rotors and impellers remain substantially centered in the pump housing and if possible, do not come into contact with the pump housing, it is useful if the Pump is designed as an axial pump, that is as a pump, in which both the intake or intake manifold of the pump as well as the discharge area or discharge nozzle (discharge nozzle) the pump coaxial with the common axis of the rotor or the rotors and the impeller or the wheels are arranged.

Furthermore, an embodiment of the invention is preferred in which a plurality of wheels in series Rotate impeller cells.

The stator of the drive according to the invention is expediently outside the pump chamber arranged, with a four-pole winding for driving the rotor is preferred. In addition, can also a two- or multi-pole winding for the radial magnetic bearing of the rotor be provided. Other windings may be provided for the axial magnetic bearing of the rotor become. These windings are expedient in which the rotor or rotor ring directly surrounding wall portion of the pump housing arranged. For this purpose, e.g. special Recesses may be provided in the wall of the pump housing.

In the preferred embodiment of the invention, the radial clearance of the rotor is at most 1 to 2 mm and the axial play maximum 0.5 to 1 mm. It should be remembered that due to the expediently rigid and non-rotatable connection of the rotor or the rotor hub with the drive shaft the impellers in the same way on each radial and axial movement of the rotor the or the wheels is transmitted, so that the wheels in their Laufradzellen, that is opposite the partition walls provided in the pump chamber, which are the individual pump cells or impeller cells define, must have a corresponding radial and axial clearance. Out For this reason, it is of course preferred for a high efficiency of the pump, if the radial and axial play is kept as small as possible, but without running the risk that it To frequent or even regular contact of the rotor with the surrounding wall areas the pump housing comes.

Of course, the windings for magnetic bearing should be independent of the stator windings the reluctance motor be switchable, so that the magnetic bearing both at slow running can be guaranteed as well as at standstill of the rotor.

Any seals that exist between individual components of the pump housing or e.g. also between a hub of the rotor and the corresponding drive shaft for the wheels provided should, if possible, be open to the pump room and well accessible, that is neither before the seals should still between the seals and surrounding wall areas gendwelchen narrow, narrow sealing gaps remain, in which the pumping medium penetrate could and would be bad to clean. Instead, the seals to the pump room should be largely open and the gaskets on the inner walls of the pump should be designed so that the transition from sealing surface to adjacent housing surface always relatively abrupt and at an angle of more than 30 °, so that on this Way narrow and narrow sealing gaps are avoided.

For more details on the arrangement and design of the seals is on the above cited DE 102 00 579.6.

The rotor is suitably as spoked wheel with a hub and an annular rim as well typically three to a maximum of six spokes formed, which hub and rim or rim ring connect to each other, wherein the actual rotor, made of soft magnetic material with tooth-like radial projections, on the ring or rim area of such Spoked wheel limited. The spokes should have a cross section that allows the passage of the Pump medium hindered as little as possible, since the spokes in the intake and / or in the Exhaust area of the pumping medium are located.

Further advantages, features and applications of the present invention will be clearly from the following description of a preferred embodiment and the associated Figure.

The single FIGURE shows an axial longitudinal section through a preferred embodiment of the invention Centrifugal pump. The total designated 10 centrifugal pump consists of a multi-part pump housing, which in detail from a suction cover 1, a pressure lid 2, a first motor housing 3, a second motor housing 3 'as well as pump cell housings 13 is formed. Especially on the motor housing sections 3 and 3 'can additionally cooling fins 25 may be provided. The individual housing sections are sealed by means of sealing rings 6 and 7, respectively connected with each other.

The pump housing described above thus defines a pumping space 20, which has an intake area 26 and an ejection region or pressure region 27, wherein the actual pumping effect is generated by three successive impeller cells, which are separated by partitions 36 and 35 and housing sections 13 are defined. The intake manifold 16 and the discharge port 17 are arranged coaxially with the common axis 18 of the wheels 4 and the rotors 5. The first Impeller cell has a drive shaft 19 annularly surrounding the inlet opening 29, the pushes Pumping medium radially outward, from where it passes over baffles 21 in the next impeller cell is, which also has a central, annular inlet opening.

After passing through a third impeller cell, the pumping medium passes according to the illustrated Arrows in the discharge or pressure area 27 and from there through the discharge port 17 after outside or in a pressure line. As you can see, the pump medium flows through both in the process Intake region 26 as well as in the pressure region 27, the spoked wheels of the two rotors 5 and 5 '. In In the illustrated embodiment, the spokes 14 of the spoke wheels have a circular shape However, they could just as well have an oblong or oval or flat cross-section have and be employed against the axis 18 propeller-like. The rotors 5 are only very shown schematically. The flat, recessed bars 23, 24 represent soft magnetic Elements or recesses between them. The in the surrounding pump housing. 3 Shown, flat, bar-shaped elements 12, 22 represent the space for stator windings or for magnetic bearing windings.

The radially outer circumferential surface of a rotor 5 is formed by a slightly protruding, circumferential Web 9 formed, which could be divided into two or more narrower webs and which serves as an emergency bearing, in the event that there is a contact of the rotor 5 with the inner wall of the surrounding housing 3 comes. A similar web 9 is also on the axial outside of the rotors 5 and 5 'are provided, which also opposite respective inner surfaces of the pump housing, However, under normal operating conditions in a small, but essentially constant distance of the order of 0.5 mm to these surfaces are kept.

The radial play of the webs or cams 9 on the rotors 5 and 5 'is a maximum of 1 to 2 mm. A corresponding radial clearance thus have the wheels or impeller blades 4, the firm are mounted on a shaft 19 which in turn fixedly and rigidly connected to the hub 15 of the rotor 5 is. The rotor 5 and the wheels 4 therefore rotate about a common axis 18. Die Pump cells are formed by partitions 35, 36 which sandwich one of the impeller blades Include 4 repainted volumes. Central to the shaft 19, the first points Impeller cell on an annular suction port 29. The medium is passed through the impeller blades 4 guided radially outward into the pressure region 39 of the impeller cell in question and is from there About baffles 21 again the next, annular intake of a next impeller cell fed, etc., until the pumping medium finally from the last impeller cell in the pressure chamber 27 is ejected.

Both entering through the intake manifold 16 in the intake 20 pumping medium as also in the pressure region 27 and the corresponding discharge nozzle 17 emerging pumping medium must each pass between the spokes 14 of the rotors 5 and 5 '.

The cross section of the spokes is shown here as a circular cross section, but this can Cross section also be oval or oblong-flat and generally be designed so that it flows through the Pump medium as little resistance opposes or the pumping flow still supported. Conveniently, each rotor 5, 5 'has only three or four corresponding spokes.

The wheels 4 and the rotors 5, 5 'are fixedly connected to each other via the shaft 19, wherein individual Shaft sections in each case via seals 8 with the hubs 15 of the rotors 5, 5 'and the hubs the wheels 4 are connected. These seals 8 are, as it is with the seals 6 and 7 recognizes sealing rings, which with a considerable part of their peripheral surface to the inner Pump room are exposed and thus well washed by the pumping medium.

The pump is constructed so that it consists of as many similar parts. For example the suction cover 1 and the pressure cover 2 are identical components, which are only mirror images are arranged to each other. Also, the pump housing sections 3, 3 ', the same time the stator form the reluctance motors are identically constructed and only mirror images of each other arranged. The same applies to the rotors 5 including the associated spokes 14 and Hubs 22. Finally, the individual pump cell housing or pressure cover 13 of the various Pump cells formed identical, that is, they each have a cylindrical housing portion 13 and a radially inwardly extending partition 35, which the suction cover the next impeller cell forms. On the pressure side of each of the impeller cells are corresponding Guiding plates 21 provided on the partition wall 35. As can be seen, are shown in the Embodiment two identical impeller cells with corresponding identical housing sections 13 arranged one behind the other. A third cell consists of only one impeller 4.

The housing sections 3, 3 ', which form the stators to the reluctance, also have still cooling fins 25 on.

The axial arrangement of the suction nozzle 16 and the pressure port 17 causes the wheels experience no effective load in a radial direction, so that it is easier, the rotors 5, 5 'in the radial direction to store magnetically.

The axial magnetic bearing is independent of the radial bearing.

As you can see, the shaft no longer needs any connection to an outside of the pump Drive and there are no sliding seals or other types of seals provided to which could be part of the pumping medium. Regardless, instead of one could magnetic bearing and one or two stationary Gleitdichtlager for the shaft 19 is provided become.

Claims (16)

1. A centrifugal pump (10) comprising a pump housing which includes a pump chamber (20) which has a suction intake region (26) and a discharge region (27), at least one impeller (4) which is mounted rotatably within the pump chamber (20) about an impeller axis (18), and an impeller drive, wherein the impeller drive comprises at least one reluctance motor (3, 5), wherein the electrically contact-less rotor (5) is supported magnetically in the interior of the pump chamber (20) and its stator is arranged at or in the housing portion (3) of the pump (10), which surrounds the rotor, characterised in that there are provided two axially spaced reluctance motors with a respective rotor, which are arranged axially respectively in front of and behind an impeller or an impeller group.
2. A centrifugal pump according to claim 1 characterised in that the rotor (5) is magnetically supported in contact-free relationship in the pump chamber both in the radial direction and also in the axial direction.
3. A centrifugal pump according to claim 1 or claim 2 characterised in that the at least one impeller (4) is coupled directly to the rotor (5).
4. A centrifugal pump according to one of claims 1 to 3 characterised in that the rotor substantially comprises a smooth ring connected to a central drive shaft, wherein intermediate spaces between radial rotor projections are filled by non-magnetic material or are covered by a rotor casing.
5. A centrifugal pump according to one of claims 1 to 4 characterised in that the rotor has sliding projections which protrude slightly beyond the rotor surface on its faces which are towards the inside walls of the pump housing.
6. A centrifugal pump according to claim 5 characterised in that the sliding projections are provided in the form of annularly peripherally extending limbs along the outside peripheral surface and/or along an axial end face of the rotor.
7. A centrifugal pump according to one of claims 1 to 6 characterised in that the rotor is in the form of a spoked wheel.
8. A centrifugal pump according to claim 1 characterised in that a respective rotor is provided in the suction intake region and in the outlet region of the pump chamber.
9. A centrifugal pump according to one of claims 1 to 8 characterised in that a plurality of impellers are arranged in axially successively connected pump cells within the pump chamber.
10. A centrifugal pump according to one of claims 1 to 9 characterised in that the reluctance motor is a four-pole motor and has windings which are independent of the pole windings for a magnetic support means.
11. A centrifugal pump according to claim 10 characterised in that the windings are provided in the wall regions of the pump housing, which immediately surround the rotor or rotors.
12. A centrifugal pump according to claim 11 characterised in that the windings are provided in recesses in the wall of the pump housing.
13. A centrifugal pump according to one of claims 1 to 12 characterised in that the rotor surface or at least the sliding projections provided on the rotor surface comprise a material which has a low level of sliding friction with the inside wall of the pump housing.
14. A centrifugal pump according to one of claims 1 to 13 characterised in that the rotor has a maximum radial clearance of 1 to 2 mm and a maximum axial clearance of 0.5 to 1 mm in the pump housing.
15. A centrifugal pump according to one of claims 1 to 14 characterised in that the pump has seals which are readily accessible and open towards the pump chamber without narrow sealing gaps.
16. A centrifugal pump according to one of claims 1 to 15 characterised in that it is in the form of an axial pump with a coaxially arranged pump inlet and an also coaxially arranged pump outlet.

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