EP2708754A2 - Pump - Google Patents

Abstract

The pump (11) has a pump chamber (13) and a rotating impeller (30). An inlet (16) is lead into the pump chamber and an outlet (19) is lead out from the pump chamber. A pump motor (20) is provided with a rotor (22), for driving the impeller. The rotor and the impeller are connected to each other. The impeller is supported in the axial direction towards the inlet. A thrust bearing (39) is provided against axial support and is located on a rotational axis of the rotor.

Description

The invention relates to a pump according to the preamble of claim 1.

From the DE 19921365 B4 is known a corresponding pump. An axial support for the impeller against the pump housing is achieved here by two sliding rings as plain bearings, which are arranged between an end face of the impeller and a shoulder in the pump housing at the inlet. In addition to an axial support for the impeller or an assembly of impeller and rotor of the pump motor so a seal is created between the suction side of the impeller inlet and pressure side impeller outlet to prevent backflow through the gap between the pump housing and impeller back to the inlet. Such reflux would significantly reduce the efficiency of the pump.

Task and solution

The invention has for its object to provide an aforementioned pump, can be avoided with the disadvantages of the prior art and in particular a practical axial support of the impeller is possible with simple production.

This object is achieved by a pump with the features of claim 1. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. The wording of the claims is incorporated herein by express reference.

It is envisaged that the pump has a pump chamber and a rotor or impeller rotating therein. Into the pump chamber in a pump housing introduces an inlet and an outlet leads out again. To drive the impeller, the pump has a pump motor with a rotor, wherein rotor and impeller are interconnected. Advantageously, the pump motor is brushless. The impeller, which is usually pulled towards the inlet during operation, is supported in this axial direction towards the inlet or away from the rotor, for which purpose an axial support against an axial bearing is provided.

According to the invention, the axial bearing is located on a rotation axis or axis of rotation of the rotor, ie in the center. This means that the axis of rotation of the rotor and thus also the impeller passes through a bearing surface of the thrust bearing. In this case, this axis of rotation of the rotor must not be confused with the motor axis, although of course the axis of rotation passes centrally through the motor axis.

An advantage of this central design and arrangement of the thrust bearing is that such a necessary bearing surface can be kept relatively small. Likewise, the relative speed at which the bearing surfaces move against each other on the axial bearing is relatively low. As a result, on the one hand, the size can be reduced or it is possible to reduce the amount of material for the axial bearing, which is usually special, difficult to process and / or expensive material. At the same time, the resulting compressive forces in such a pump are not too great in that the impeller is pulled to the inlet. In this respect, these forces can be absorbed even with a relatively small-area axial support. In addition, as a very low-friction storage can be achieved compared to the aforementioned storage by means of sliding rings, which in turn has an advantageous effect on energy consumption and efficiency of the pump.

Another advantage is that the arrangement of the impeller in the pump housing is much more precise possible while simplifying the manufacture of the pump. By bearing with the thrust bearing in the area where it is important for the impeller, it can be very precise. This will be explained in more detail below.

In an advantageous embodiment of the invention, rotor and impeller are designed as a structural unit. They can not only be mounted together somehow, but advantageously be insoluble or made in one piece. The formation of rotor and impeller as a unit is advantageously carried out before assembly of the pump. For example, rotor and impeller can be made as a unit in one piece in a plastic injection molding of plastic, particularly advantageous in two or three steps.

Furthermore, the assembly of rotor and impeller can be advantageously designed such that the impeller is, so to speak, placed directly on the rotor or at least no pump chamber wall is located therebetween. In particular, no pump chamber floor should be in between, so that construction or assembly are very easy to perform. For this purpose, the impeller advantageously has a larger diameter than the rotor, so that the structural unit can be mounted in the direction of the engine.

In an embodiment of the invention, the thrust bearing is in extension of the inlet, in the region or within the inlet. It can thereby be achieved that the basic design of the impeller does not have to be changed very much by the thrust bearing according to the invention.

Furthermore, the inlet of one of the parts of the pump housing which are closest to the impeller in the region of the rotational axis of the rotor is particularly advantageous. Such is the arrangement of the Axial bearings relatively easy. Finally, arranged in the inlet region thrust bearing also disturbs the inflow of the pumped fluid into the pump into little, since such impeller pumps are usually pressure pumps and no suction pumps. Again, the arrangement of the thrust bearing on the axis of rotation of the rotor centrally in the inlet of advantage, which advantageously also extends coaxially to this axis of rotation, whereby no large inflow resistance is formed.

In an advantageous further embodiment of the invention, the thrust bearing can be seen radially within the impeller or at its axial height, in particular in its upper end region. So just the structure of the impeller can be largely conventional.

In a preferred embodiment of the invention, the thrust bearing is substantially free in the inlet or is arranged there. It is supported by means of several supports at the inlet, in particular in the manner of struts, which are particularly preferably in the radial direction and may be formed flat in cross-section such that they just form the lowest possible flow resistance in the axial direction. There may be provided several supports for the thrust bearing, which can be distributed around the thrust bearing or in the same direction in the same direction. For example, it may be two to four supports for a sufficiently stable mounting of the thrust bearing.

The impeller may have a tubular top facing towards the inlet. The inlet, in particular an aforementioned elongated inlet, may comprise or form a collar which overlaps the tubular upper part of the impeller and which likewise has approximately the shape of a short tube. This collar can in particular form a taper of the inlet. The tubular upper part and the collar overlap each other in the axial direction, which serves to avoid too large aforementioned backflow of water from the pressure side to the suction side. It can be particularly advantageous, the collar a piece extend into the tubular upper part of the impeller. The supports provided for the axial bearing extend at the end of this collar or as far as possible in the direction of the impeller and can thus be arranged within the tubular upper part of the impeller. Thus, the thrust bearing extends quasi as far as possible to the impeller.

Advantageously, the thrust bearing on a sliding bearing on which the impeller or the assembly formed with it rests. The plain bearing may have a bearing surface. Particularly advantageous is a bearing projection arranged on a projection or a survey in the interior of the impeller, said bearing projection can cooperate with the sliding bearing of the thrust bearing. Slide bearing and bearing projection can be designed such that they have a curvature and indentation, which are applied against each other or to each other and rotate together. Due to the shape of the curvature and indentation can advantageously be achieved that a centering of the assembly or the impeller is carried on the axis of rotation of the rotor and thus also the entire pump. This means that the other storage of the unit or the rotor of the pump motor must be less expensive, in particular no further radial bearings needed because their centering on the side facing away from the impeller side of the unit only needs to be present and not on the entire length of the unit must extend. Buckle and indentation are advantageously designed such that the indentation has a larger radius or is less curved than the curvature that lies in it. Thus, advantageously, the aforementioned self-centering.

It is possible, the slide bearing on the thrust bearing concave curved form away from the impeller and the bearing projection on the impeller with a convex curvature away from this. Thus, virtually engages a tip or curvature of the bearing projection of the impeller in the recess or indentation of the thrust bearing at the inlet of the pump housing. Preference is given to an approximately uniform or rounded curvature. For each Convex convex part, so to speak, the tip on the thrust bearing, could actually be provided a very fine tip. Then, however, a point-shaped storage would essentially result, which in turn is susceptible to wear and also makes very high demands on a production.

It is possible to form a part of the axial bearing made of plastic. The other part may also be made of plastic, alternatively made of metal or graphite or ceramic. At least one inwardly curved slide bearing as a recess should be made of plastic. Here, generally preferred plastics can be used for such bearings, for example polyamide, Teflon-reinforced, POM or generally fiber-reinforced plastics. Sinterbronze or brass are suitable as metallic materials, in particular because of their corrosion resistance when using the pump in a dishwasher.

A sliding bearing of the axial bearing on the pump housing or in the inlet is advantageously injected or injected. Thus, it can be attached thereto in the same operation of manufacturing the pump housing.

A bearing on the plain bearing of the thrust bearing bearing projection of the impeller is advantageously also molded or injected at this. Again, there are the benefits of simple and accurate manufacturing. Alternatively, it could also be a usable from above separate part, which in any case can not fall out of the impeller by the system pressure on the thrust bearing during operation of the pump.

Advantageously, the assembly rotates on a fixed motor axis, which runs coaxially with the axis of rotation of the rotor. This motor shaft may be fixed to the end facing away from the impeller, in particular to a motor housing at the end facing away from the inlet end of the pump. Preferably, it is a round motor shaft which rotates in a bearing bush, which is arranged in the rotor, in particular injected. The length of the motor shaft can be freely selected within wide limits. It can be almost as long as the entire assembly of rotor and impeller. But since at the other end the thrust bearing provides for the storage and in particular for the centering of the assembly, the motor axis does not need to be very long and can protrude only a few inches or only a small piece into the rotor. Essentially, this short motor axis must then ensure a radial securing or centering of the rotor or the structural unit. The centering at the other end of the assembly is formed by the thrust bearing at the inlet, which is sufficient overall.

These and other features will become apparent from the claims but also from the description and drawings, wherein the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections as well as intermediate headings does not restrict the general validity of the statements made thereunder.

Brief description of the drawings

Fig. 1

eine seitliche Schnittansicht durch eine erfindungsgemäße Pumpe mit einer Baueinheit aus Impeller und Rotor auf einer feststehenden Motorachse, die gegen ein Axiallager im Pumpeneinlass abstützbar ist,

Fig. 2

das Axiallager aus Fig. 1 in Vergrößerung im noch nicht abgestützten Zustand vor Anlaufen des Pumpenmotors,

Fig. 3

eine Draufsicht auf die Pumpe aus Fig. 1 mit Blickrichtung in den Einlass auf das Axiallager,

Fig. 4

eine Abwandlung eines Axiallagers ähnlich Fig. 2 mit umgekehrten Wölbungen und

Fig. 5

eine nochmalige weitere Abwandlung eines Axiallagers entsprechend Fig. 2.

Embodiments of the invention are shown schematically in the drawings and are explained in more detail below. In the drawings show:

Fig. 1

4 is a side sectional view through a pump according to the invention with an assembly of impeller and rotor on a fixed motor axis, which is supported against a thrust bearing in the pump inlet,

Fig. 2

the thrust bearing Fig. 1 in magnification in the not yet supported state before starting the pump motor,

Fig. 3

a plan view of the pump Fig. 1 looking in the inlet to the thrust bearing,

Fig. 4

a modification of a thrust bearing similar Fig. 2 with inverted bulges and

Fig. 5

a further further modification of a thrust bearing accordingly Fig. 2 ,

Detailed description of the embodiments

In the Fig. 1 a pump 11 according to the invention is shown in a sectional side view. It has a pump part 12 with a pump chamber 13 in a pump housing 14. The pump 11 is obviously designed as an impeller pump and can be advantageously used in a water-conducting household appliance, in particular a dishwasher or a washing machine.

In the pump chamber 13 into a central inlet 16 leads along a dash-dotted longitudinal center axis. The inlet 16 has an inlet tube 17, which opens into a radially inner collar 18. Furthermore, an outlet 19 is provided on the pump housing 14, see also the plan view Fig. 3 ,

On the other hand, the pump 11 has a motor part 20 with a stator 21 and a rotor 22, which has a rotor laminated core 23 and magnets 23 '. It is therefore a brushless wet rotor, as it is known and familiar for such applications.

In the rotor 22 is a bearing bush 25 which runs on a motor shaft 20 fixedly inserted in the motor part 26. An impeller 30 adjoins the region of the rotor 22 surrounding the rotor laminated core 23 and the magnets 23 'or is produced in one piece therewith, in particular by an aforementioned plastic injection molding. The impeller 30 has a bottom disk 31 and a cover disk 32 with therebetween arranged, curved impeller blades 33. Such impellers are known in the art, see for example the DE 102012209832.1 the same applicant with filing date of June 12, 2012. Furthermore, the impeller 30, a tubular upper part 34, which adjoins the cover plate 32. The central axis 35 raises a central projection 35 on the bottom plate 31. The motor shaft 26 may extend into this central projection 35 into it, but need not be so long and can, for example, extend only to the lower end of the bearing bush 25. At the end of the central projection 35, a bearing projection 37 is provided or arranged, which is slightly convexly curved or toward the inlet 16. This is from the following explained strong magnification in Fig. 2 clear.

To the Fig. 2 It should be noted that although an axial bearing 39 according to the invention is shown here, for the sake of clarity in a state in which no contact has yet been reached. So there is still a small distance, which may correspond, for example, a resting state of the pump 11. Opposite the bearing projection 37, the thrust bearing 39 on a bearing shell 40, which is arranged in a bearing holder 41, for example, pressed or injected. It may also be the same part. The bearing holder 41 in turn is about three struts 42, the radial arrangement of Fig. 3 can be seen on the pump housing 14 and held on the inlet tube 17 and collar 18. Also, the thrust bearing 39 and bearing holder 41 and strut 42 may advantageously be formed integrally with the inlet.

When the pump 11 starts, it pulls the impeller 30 toward the inlet 14, in the Fig. 1 So down. As a result, the bearing projection 37 comes to rest on the bearing shell 40 of the axial bearing 30. By the respective curvature ensures that a centering of the assembly of impeller 30 and rotor 22 takes place on the dot-dashed central longitudinal axis or axis of rotation of the rotor. For this purpose, the outwardly arched bearing projection 37 with a smaller radius or one The difference may, for example, be given geometrically such that the radius, in the case of circular areas or approximate circular areas, of the bearing shell 40 is 1.5 times to 4 times larger as the one of the bearing projection 37. The bearing projection 37 may consist of the same plastic as the other impeller 30. Alternatively, it may consist of a separate applied material. The same applies to the bearing shell 40, for this reference is made to the examples described above for respective material choices.

In Fig. 4 a modification of a thrust bearing 139 is shown. Basically, the principle of the arrangement of the thrust bearing 139 on the axis of rotation of the rotor is the same, also here three struts 142 are provided. The bearing holder 141 is here, however, not curved inward as in Fig. 2 but arched outwards or forms the bulged part of the thrust bearing 139th

Adjacent to the bearing projection 137 of the impeller 130 has a recess shell 138 as quasi bearing shell. This can, as indicated, made of a different material than the bearing projection 137 and be molded or attached. Similar to already in Fig. 2 are in the Fig. 4 the bulges formed differently strong for a good ratio of abutting surface and centering effect.

In Fig. 5 is a still further modification shown, the one from the Fig. 2 similar. The thrust bearing 239 here has a bearing shell 240 which is held by three struts 242. The bearing shell 240 is supported by a bearing holder 241 and is advantageously made of hard material or metal, in particular brass. At the bearing projection 237 of the impeller 230, a bearing tip 244 is provided, which advantageously also consists of metal and is attached or molded. While the bearing cup 240 is substantially curved, similar to the previous embodiments, the bearing tip 244 is much sharpened. It can either be formed directly as a tip as fine as possible, alternatively also have a flattening of about 1 mm in diameter at the front or a corresponding rounding. Especially in conjunction with the slightly more inwardly curved bearing shell 240 is achieved by a very good centering. If the respective materials are sufficiently wear-resistant, a very low-friction bearing can be achieved thereby, which in turn has an advantageous effect on energy consumption and efficiency of the pump.

Another great advantage of the design of the pump 11 with a thrust bearing 39 is that the axial position of the impeller 30 in the pump chamber 13 can be accurately determined. In particular, a gap between the impeller 30 or cover disk 32 and the tubular upper part 34 towards the pump housing 14, in particular in the region of the inlet pipe 17 or the collar 18, can be minimized without running the risk of a direct concern. As a result, a loss flow typical of impeller pumps can be reduced from the pressure side to the suction side. As a result, the efficiency or energy efficiency of the pump 11 is increased. This very precise storage is favored in addition to the axial support by the centering due to the special design of the thrust bearing 39.

Due to the design of the impeller 30 including the rotor 22 and its part of the axial bearing and a very easy and precise installation can be achieved.

Claims (15)

A pump having a pumping chamber and an impeller rotating therein, an inlet leading into the pumping chamber and leading an outlet out of the pumping chamber, the pump for driving the impeller having a pumping motor with a rotor, the rotor and the impeller being interconnected , wherein the impeller is supported in the axial direction towards the inlet and wherein for an axial support against a thrust bearing is provided, characterized in that the thrust bearing is located on a rotational axis of the rotor. Pump according to claim 1, characterized in that the rotor and impeller are formed as a unit, in particular are made in one piece, even before assembly of the pump, wherein preferably the assembly of rotor and impeller is made in one piece in a single plastic injection molding of plastic. Pump according to claim 1 or 2, characterized in that rotor and impeller are formed as a unit without Pumpenkammerwandung therebetween and arranged in the pump. Pump according to one of the preceding claims, characterized in that the thrust bearing is located in the extension of the inlet in the region thereof or within the inlet. Pump according to one of the preceding claims, characterized in that the axial bearing is radially seen within the impeller and / or at its axial height and in particular is surmounted by the impeller. Pump according to one of the preceding claims, characterized in that the thrust bearing is substantially free in the inlet and supported by a plurality of supports at the inlet, wherein preferably in the direction of rotation a plurality of supports are arranged towards the pump housing, in particular evenly distributed. Pump according to one of the preceding claims, characterized in that the impeller has a tubular upper part in the direction of the inlet, wherein the inlet has a tubular cross-section of the impeller cross-collar which forms in particular a taper of the inlet, wherein the collar a piece in the tubular upper part of the impeller extends, preferably within this tubular upper part of the impeller, the supports are arranged according to claim 6 for the thrust bearing. Pump according to one of the preceding claims, characterized in that the thrust bearing has a sliding bearing on which the impeller or the assembly is applied, wherein preferably a bearing projection on a projection in the interior of the impeller is arranged to cooperate with the sliding bearing of the thrust bearing. Pump according to claim 8, characterized in that slide bearing and bearing projection are formed such that they have a curvature and a bulge, which are mutually applied and rotate in such a way that a centering of the assembly takes place on the axis of rotation of the rotor. Pump according to claim 8 or 9, characterized in that the sliding bearing on the thrust bearing is concavely arched away from the impeller and the bearing projection is convexly curved away from the impeller. Pump according to one of claims 8 to 10, characterized in that the inwardly curved part of slide bearing or bearing projection is less curved than the other fitting thereto outwardly curved part. Pump according to one of claims 8 to 11, characterized in that a part of the thrust bearing is made of plastic, and preferably the other part of metal, wherein preferably at least the inwardly curved sliding bearing consists of plastic. Pump according to one of claims 8 to 12, characterized in that the sliding bearing is molded or injected on the pump housing. Pump according to one of claims 8 to 13, characterized in that the voltage applied to the sliding bearing bearing projection is molded or injected on the impeller. Pump according to one of the preceding claims, characterized in that the assembly rotates on a fixed motor shaft, which is preferably secured to the end facing away from the impeller end, in particular in a motor housing or attached to a motor housing, preferably arranged in the rotor bearing bush is that rotates on the motor axis.

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