Pump arrangement

A pump arrangement, in particular a magnetic clutch pump arrangement, includes a pump housing containing an impeller shaft, a containment shell which seals an enclosed chamber within the inner chamber of the pump housing, an impeller mounted on one end of the impeller shaft, an inner rotor mounted on the other end of the impeller shaft, an outer rotor which is mounted on the drive shaft and co-operates with the inner rotor, and an auxiliary impeller mounted in the chamber adjacent to a domed base of the containment can. The auxiliary impeller is secured to the inner rotor and includes vanes and impeller channels for circulation of media.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of PCT International Application No. PCT/EP2014/058706, filed Apr. 29, 2014, which claims priority under 35 U.S.C. § 119 from German Patent Application No. 10 2013 007 849.0, filed May 8, 2013, the entire disclosures of which are herein expressly incorporated by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

The invention relates to a pump arrangement, in particular magnetic clutch pump arrangement. The pump arrangement has an interior space formed by a pump casing a containment can which hermetically seals off a chamber surrounded by said containment can with respect to the interior space formed by the pump casing, an impeller shaft which can be driven in rotation about an axis of rotation, an impeller which is arranged on one end of the impeller shaft, an inner rotor arranged on the other end of the impeller shaft, an auxiliary impeller arranged in the chamber, and an outer rotor which interacts with the inner rotor.

German patent document no. DE 27 54 840 A1 has disclosed a magnetic clutch pump arrangement of said type with an auxiliary impeller. The auxiliary impeller is of disk-shaped construction and is equipped with radial bores. However, said embodiment, with regard to its efficiency, constitutes an inefficient impeller or delivery variant, and lowers the overall efficiency of the pump arrangement. Furthermore, a not inconsiderable level of outlay is required to produce the auxiliary impeller.

It is the object of the invention to provide a magnetic clutch pump arrangement with a forced-lubrication flow drive which is simple to produce and which exhibits improved efficiency.

The object of the invention is achieved in that the auxiliary impeller is fastened to the inner rotor.

Since the auxiliary impeller is fastened by way of its open side to that face side of the inner rotor which faces toward the base of the containment can, it is possible for the advantages of a closed channel-type impeller to be utilized by way of an open impeller, which is much easier to produce. Furthermore, the impeller does not have a hub and is easy to assemble and disassemble.

In one refinement, the containment can has a main body with an open side and with a side which is situated opposite the open side and which is closed by way of a domed base, and the auxiliary impeller has a rear shroud, whose outer surface facing toward the base of the containment can has a domed form.

By virtue of the fact that the domed form of the outer surface of the rear shroud substantially corresponds to the domed form of the base of the containment can, the dead space that is normally spanned by the domed base of the containment can is filled, whereby no additional axial structural space required by the magnetic clutch is taken up. Furthermore, the pressure resistance of the containment can is not unnecessarily reduced.

To improve the flow guidance of the medium as it enters a fluid inlet region of the auxiliary impeller, a paraboloid-like elevation is ideally provided in the center of the rear shroud.

In a further refinement, it is provided that, on the rear shroud, at a radial distance from the elevation, there are formed multiple raised portions which form vanes and corresponding impeller channels of the auxiliary impeller.

In a further refinement, it is proposed that the impeller channels have a channel base which is similar in form to a rampant three-center arch. This leads to an improvement in flow guidance.

In a further refinement of the invention, it is provided that the upper side of the vanes opposite the rear shroud, has a step close to the channel inlet edge. The step serves as an abutment shoulder and centering device for precise alignment of the auxiliary impeller fastened to the inner rotor.

For simple and inexpensive production, the impeller shaft and the inner rotor form a cover shroud, situated opposite the rear shroud, of the auxiliary impeller.

In a further advantageous refinement, in the raised portions which form the vanes, there are formed further impeller channels which extend in a radial direction from the outer lateral surface as far as a point close to the step.

To improve the flow guidance of the medium, the further impeller channels have a channel base which, at least in part, has a domed form which corresponds substantially to the domed form of the outer surface of the rear shroud.

According to the invention, the impeller shaft has an axial channel which is connected to the fluid inlet region of the auxiliary impeller.

In the context of the invention, it is proposed that, in a further embodiment, in the inner rotor, there are provided fluid channels which issue into the further impeller channels of the auxiliary impeller.

DETAILED DESCRIPTION

FIGS. 1 and 2show a pump arrangement1in the form of a magnetic clutch pump arrangement. The pump arrangement1has a multi-part pump casing2of a centrifugal pump, which pump casing comprises a hydraulic casing3in the form of a spiral casing, a casing cover4, a bearing carrier cage5, a bearing carrier6and a bearing cover7.

The hydraulic casing3has an inlet opening8for the intake of a delivery medium and has an outlet opening9for the discharge of the delivery medium. The casing cover4is arranged on that side of the hydraulic casing3which is situated opposite the inlet opening8. The bearing carrier cage5is fastened to that side of the casing cover4which is opposite from the hydraulic casing3. The bearing carrier6is mounted on that side of the bearing carrier cage5which is situated opposite the casing cover4. The bearing cover7in turn is fastened to that side of the bearing carrier6which is opposite from the bearing carrier cage5.

A containment can10is fastened to that side of the casing cover4which is opposite from the hydraulic casing3, and said containment can extends at least partially through an interior space11delimited by the pump casing2, in particular by the casing cover4, by the bearing carrier cage5and by the bearing carrier6. The containment can10hermetically seals off a chamber12, which is enclosed by said containment can and by the casing cover4, with respect to the interior space11.

An impeller shaft13which is rotatable about an axis of rotation A extends from a flow chamber14, which is delimited by the hydraulic casing3and by the casing cover4, into the chamber12through an opening15provided in the casing cover4.

An impeller16is fastened to a shaft end, situated within the flow chamber14, of the impeller shaft13, and an inner rotor17arranged within the chamber12is arranged on the opposite shaft end, which has two shaft sections13a,13bwith increasing diameters in each case. The inner rotor17is equipped with multiple magnets18which are arranged on that side of the inner rotor17which faces toward the containment can10. An auxiliary impeller20is fastened to the inner rotor17by way of screws19or other suitable fastening means.

Between the impeller16and the inner rotor17there is arranged a bearing arrangement21which is operatively connected to the impeller shaft13, which can be driven in rotation about the axis of rotation A.

A drive motor, preferably an electric motor, which is not illustrated drives a drive shaft22. The drive shaft22, which can be driven about the axis of rotation A, is arranged substantially coaxially with respect to the impeller shaft13. The drive shaft22extends through the bearing cover7, through the bearing carrier6, and at least partially into the bearing carrier cage5. The drive shaft22is mounted in two ball bearings23,24which are accommodated in the bearing carrier6. On the free end of the drive shaft22there is arranged an outer rotor26, which bears multiple magnets25. The magnets25are arranged on that side of the outer rotor26which faces toward the containment can10. The outer rotor26extends at least partially over the containment can10and interacts with the inner rotor17such that the rotating outer rotor26, by way of magnetic forces, sets the inner rotor17and thus likewise the impeller shaft13and the impeller16in rotation.

The containment can10, illustrated on an enlarged scale inFIG. 3, has a substantially cylindrical main body27. The main body27is open on the side facing toward the casing cover4, and is closed by way of a domed base28on the side situated opposite the open side. On the open side, there is arranged a ring-like attachment flange29which is formed integrally with the main body27or which is fastened to the latter by welding or other suitable fastening means or devices, for example screws, rivets or the like. The attachment flange29has multiple bores30which extend parallel to the axis of rotation A and through which screws31can be passed and screwed into corresponding threaded bores in the casing cover4. The base28of the containment can10is formed by a substantially spherical segment-shaped spherical cap region32and an outer rim region33which forms the transition region between main body27and spherical cap region32.

As can be seen fromFIGS. 3 and 4, the auxiliary impeller20has a rear shroud34, whose outer surface, facing toward the base28of the containment can10, has a domed form. The domed form of the outer surface of the rear shroud34substantially corresponds to the domed form of the base28of the containment can10. In the center of the rear shroud34, a paraboloid-like elevation35is provided in a fluid inlet region36. Furthermore, multiple raised portions are formed on the rear shroud34at a radial distance from the elevation35, which raised portions form vanes37with a channel inlet edge38, facing toward the elevation35, and corresponding impeller channels39of the auxiliary impeller20. The elevation35is conducive to improving the flow guidance of the medium as it enters the impeller channels39of the auxiliary impeller20. In the exemplary embodiment shown, the vanes37extend in curved fashion from the fluid inlet region36to an outer lateral surface40of the auxiliary impeller20. The impeller channels39have a channel base41, which in turn has a domed form substantially corresponding to the domed form of the outer surface of the rear shroud34. The channel base41of the impeller channels39is, in the longitudinal section shown, similar in form to a rampant three-center arch, as illustrated inFIG. 6. The impeller channels39have a first width W1at the fluid inlet region36and have a second width W2at the outer lateral surface40, wherein the second width W2is greater than the first width W1or at least corresponds to the first width W1.

The upper side of the vanes37has a step42close to the channel inlet edge38, which step serves as an abutment shoulder and centering device for the auxiliary impeller20fastened to the inner rotor17. A cover shroud which is situated opposite the rear shroud34and which closes off the impeller channels39formed between the vanes37can be dispensed with, as the impeller shaft13and the inner rotor17form the cover shroud of the auxiliary impeller20. Owing to its semi-open construction, the auxiliary impeller20is easy to produce both by casting, as it is easily demoldable, and by mechanical machining, as the impeller channels can be easily milled out.

At a distance radially outward from the steps42, installation holes43are provided which extend through the rear shroud34and the vanes37, through which installation holes the screws19are passed and screwed into the threaded bores44formed on that side of the inner rotor17which faces toward the base28of the containment can10. The auxiliary impeller20can thus be fastened by way of its open side to that face side of the inner rotor17which faces toward the base28of the containment can10. On the side situated opposite the channel inlet edge38, each vane37preferably has at least one recess45. An additional pressure increase is generated in this way.

As shown inFIG. 2, in the casing cover4, there are provided at least one passage opening46and, in a bearing ring carrier47which fixes the bearing arrangement21, at least one radial passage opening48. The passage opening48extends through a flange-like region49by which the bearing ring carrier47, which is positioned coaxially with respect to the axis of rotation A and which extends into the chamber12, is fastened to the casing cover4by way of a screw connection (not illustrated). The passage openings46and48connect the flow chamber14to an inner region50of the bearing ring carrier47.

Thus, for the cooling and lubrication of the bearing arrangement21, delivery medium can be extracted from the flow chamber14and supplied by the passage openings46and48to the bearing arrangement21. Via at least one radial bore51, the delivery medium is delivered from the inner region50into an axial channel52, which extends from a region of the impeller shaft13surrounded by the bearing arrangement21to that end of the impeller shaft13which is situated within the chamber12, and thus to the auxiliary impeller20. The axial channel52is thus connected to the fluid inlet region36of the auxiliary impeller20. If necessary, at least one further radial bore53is formed which is likewise connected to the axial channel52formed in the impeller shaft13. The auxiliary impeller20delivers the medium used for cooling and lubrication radially outward into the chamber12, from where said medium is delivered back into the flow chamber14via multiple axial passage openings54formed in the flange-like region49and passage openings55formed in the casing cover4, said passage openings being shown inFIG. 1.

FIGS. 5 to 8show a further exemplary embodiment of the invention. The auxiliary impeller20, illustrated in detail inFIG. 5, has vanes37which are formed by raised portions on the rear shroud34and which define impeller channels39which extend radially outward from the fluid inlet region36. In the exemplary embodiment shown, the vanes37extend rectilinearly from the fluid inlet region36to the outer lateral surface40of the auxiliary impeller20. The impeller channels39have a first width W1at the fluid inlet region36and a second width W2at the outer lateral surface40, wherein the second width W2is greater than the first width W1or at least corresponds to the first width W1.

Further impeller channels56are formed in the raised portions which form the vanes37, which further impeller channels extend in the radial direction likewise in substantially straight form, that is to say without a curvature or without a significant curvature, from the outer lateral surface40to a point close to the step42, and which further impeller channels have a channel base57which, at least in part, has a domed form which substantially corresponds to the domed form of the outer surface of the rear shroud34. As viewed in longitudinal section, the channel base57of the impeller channels56is similar in form to a rampant three-center arch, as illustrated inFIG. 7. The impeller channels56widen toward the outer lateral surface40proceeding from the region adjacent to the step42, and said impeller channels have a first width W3at a fluid inlet region56aand a second width W4at the outer lateral surface40, wherein the second width W4is greater than the first width W3or at least corresponds to the first width W3.

FIGS. 6 to 8show a pump arrangement1which is equipped with an auxiliary impeller20as illustrated inFIG. 5. Here, the view inFIGS. 6 and 7corresponds to the view inFIG. 1. The view inFIG. 8corresponds to the view inFIG. 2. As can be seen fromFIG. 6, the at least one radial bore53leads into an axial channel52which is shorter than inFIGS. 1 and 2. Furthermore, the bearing ring carrier47has fluid channels58running parallel to the axis of rotation A, which fluid channels connect the inner region50of the bearing ring carrier47to the chamber12which is enclosed by the containment can10and by the casing cover4.

FIG. 7shows the pump arrangement1shown inFIG. 6with an inner rotor17rotated through 45° about the axis of rotation A. In the inner rotor17there are provided fluid channels59which are arranged approximately at the same radial distance from the axis of rotation A as the fluid channels58of the bearing ring carrier47, and which are thus substantially in alignment with said fluid channels58at least in the position illustrated. The fluid channels59issue into the impeller channels56of the auxiliary impeller20, which is arranged on that face side of the inner rotor17which faces toward the base28of the containment can10.

For the cooling and lubrication of the bearing arrangement21, delivery medium is extracted from the flow chamber14and, as shown inFIG. 8, is supplied to the bearing arrangement21via the at least one passage opening46in the housing cover4and via the at least one passage opening48in the flange-like region49of the bearing ring carrier47. Via the at least one radial bore53, the delivery medium is delivered from the inner region50of the bearing ring carrier47into the axial channel52and to the auxiliary impeller20. By way of the impeller channels39, the auxiliary impeller20delivers the medium used for cooling and lubrication radially outward into the chamber12.

At the same time, as perFIG. 7, the delivery medium extracted from the flow chamber14is delivered from the inner region50of the bearing ring carrier47, via the fluid channels59formed in the inner rotor17, into the impeller channels56of the auxiliary impeller20, and radially outward into the chamber12.

From the chamber12, the medium is delivered back into the flow chamber14via the at least one passage opening55(shown inFIGS. 6 and 7) formed in the casing cover4.

In the exemplary embodiments shown, the auxiliary impeller20is shown either with the impeller channels39or with the impeller channels39and the impeller channels56. It is self-evident that the auxiliary impeller20may also be equipped only with the impeller channels56.

LIST OF REFERENCE DESIGNATIONS