DE102012209832B3 - Pump and method of making an impeller for a pump - Google Patents

Abstract

In a centrifugal pump with an impeller for conveying fluid with central axial suction and radial outlet of the fluid to be delivered from the impeller, the impeller has an upper cover disk and a lower cover disk and a plurality of blades therebetween. The blades extend in the radially inner region substantially in the axial direction of the pump parallel to the axis of rotation of the impeller and thus are upright, wherein they are increasingly inclined in their course radially outward or obliquely.

Description

Field of application and state of the art

The invention relates to a pump, in particular for household appliances such as dishwashers or washing machines. The pump is designed as a so-called centrifugal pump. Likewise, the invention relates to a method for producing an impeller for such a pump.

Such a pump is out of the EP 2150165 B1 known. The centrifugal pump described therein has an impeller with an upper cover plate and a lower cover plate, between which there are several blades.

Task and solution

The invention has for its object to provide an aforementioned pump and a method for producing an impeller for such a pump with which problems of the prior art can be avoided and in particular an efficient delivery of fluid is possible and advantageously an easy to manufacture, reliably functioning impeller can be provided.

This object is achieved by a pump with the features of claim 1 and a method for producing an impeller with the features of claim 10. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below. Some of the features listed below are only described for the pump or impeller or just for the procedure. However, they should apply regardless of both the impeller and the pump as well as for the procedure. The wording of the claims is incorporated herein by express reference.

It is provided in such a pump, in particular for household appliances such as dishwashers or washing machines, that it has an impeller for conveying fluid, wherein the pump is designed with the impeller for a function as a centrifugal pump with central axial suction and radial outlet of the fluid to be delivered from the impeller. The impeller has an upper cover disk and a lower cover disk, wherein a plurality of blades lie or are arranged between the cover disk. The impeller is thus designed as a so-called closed impeller.

According to the invention, the blades extend in the radially inner region substantially upright or more strongly in the axial direction of the pump or the impeller parallel to the axis of rotation of the impeller than in their further course to the outside or towards the radially outer region. Advantageously, the blades are thus less inclined in the radially inner region relative to the longitudinal central axis than in the radially outer region. Particularly advantageous they are approximately upright in the radially inner region.

In their further course to the outside or to the radially outer region, the blades are thus increasingly inclined or inclined or increasingly inclined. Thus, its inclination advantageously changes from little or no inclination in the radially inner region to the maximum inclination in the radially outer end region.

As a result, on the one hand, an advantageous conveying effect or flow guidance for the fluid can be achieved. Furthermore, just for the later described in detail case, that the entire impeller is formed in one piece and the blades extend from the lower cover plate to the upper cover plate, given better manufacturability, in particular by plastic injection molding.

In a further embodiment of the invention, it is provided that the inclination of the blades is designed such that the blades are inclined towards the upper cover disk in the direction of rotation of the impeller or are inclined. Thus, in tests, the aforementioned better values with regard to flow guidance or better hydraulic characteristics can be established, for example in comparison with the impellers from the aforementioned EP 2150165 A with upright blades.

In a further embodiment of the invention, the change in inclination from monotonous radially inward to radially outward increase. This means that it is at least not falling again. Advantageously, it is steadily or strictly monotonically increasingly, the inclination thus increases continuously. It can grow evenly, but it does not have to. If the inclination increases approximately evenly, on the one hand the shape can be easily produced and on the other hand this in turn improves the flow guidance.

It can be provided that in the radially inner region only a very short region of the blade is upright or the blade immediately begins to tilt towards the upper cover disk in the direction of rotation of the impeller.

A maximum angle of inclination of the blades in the radially outer region may be less than 75 ° to the axis of rotation. Advantageously, it is between 45 ° and 70 °. It may be, for example, at the lower cover plate about 70 ° and at the top about 50 °.

In a further embodiment of the invention, the blade can differ in cross section from a straight extension. This means that it can be slightly curved in its course from the lower cover plate to the upper cover plate, advantageously again in the direction of rotation. The curvature may be a few percent of the extension length between the lower cover disk and the upper cover disk, for example 1% to 10% or even to 20%. It is preferably about 10%.

In yet another advantageous embodiment of the invention, the blades are curved in its longitudinal course from radially inward to radially outward, particularly advantageous against the direction of rotation curved. A curvature may preferably be uniform. As an approximate measure of the curvature, it may be between 5% and 30% of the extension length between the radially innermost and radially outermost points beyond the bond line between these two points, preferably 15% to 20%.

It is considered preferable if all blades of the impeller are formed identically. Although this not so much for the manufacturing process special advantages, but for the hydraulic properties and the concentricity of the impeller. Particularly advantageously, the impeller also has only said blades.

Preferably, an impeller has three to eight blades. More preferably, there are four to six blades. The blades do not point with their extension direction on the axis of rotation of the impeller, but past it. Furthermore, the vanes also do not occupy the radially innermost region of the impeller or are disposed only outside thereof. For example, the innermost 10% to 40% of the radius may be free of blades.

In a further advantageous embodiment of the invention, a central protruding projection is arranged on the lower cover plate of the impeller. This projection can project beyond the blades in the direction of the upper cover disk. The blades should extend to just before the projection, so have at least in the region of the lower cover plate only a small radial distance to him.

It is considered advantageous if the blades and the cover plates of the impeller, in particular also the aforementioned projection, are produced integrally or in one piece. Above all, a plastic injection molding process is suitable for this purpose. In such a plastic injection molding process, it is possible that only linear slides are moved into areas between the later blades of the impeller along a plane perpendicular to the axis of rotation of the impeller. The radially inner region of the impeller together with the surface of the top of the upper cover plate is produced by at least one further linear slide, which is moved up along the direction of the axis of rotation of the impeller. Thus, it is possible that for the production of the impeller by plastic injection molding only linear slide must be used and no otherwise commonly required curve slide. This greatly simplifies the manufacturing process and reduces manufacturing time and cost. In order to produce the blades by the aforementioned linear slide perpendicular to the axis of rotation of the impeller, it is considered advantageous if the lower cover plate and the upper cover plate not only in the radially outer region parallel or at the same distance from each other or from the inside out at least not nearly to each other, but are also particularly advantageous even. Advantageously, the entire lower cover plate is flat to the interior of the impeller. This applies particularly advantageous for the underside of the upper cover plate. Since the said linear slide should be retracted and extended perpendicular to the axis of rotation of the impeller in a direction which passes by the axis of rotation of the impeller, said equidistant spacings of the cover plates are mutually necessary at least at their sides facing each other.

It may be provided that a linear slide is used per blade, wherein advantageously a linear slide forms the front of a blade and the back of an adjacent blade or etc .. Its sliding direction can pass through the corresponding blade and preferably at least a portion of in the direction of rotation, hit the next following blade. The inclination of the blades in relation to the axis of rotation of the impeller, which becomes stronger from radially inward to outward, does not obstruct the use of the linear slide in any way.

In an advantageous further embodiment of the invention, the linear slide for all blades are retracted and extended from radially outside substantially in the same plane. This plane should be parallel to the lower cover plate, in particular also to the upper cover plate, or rather parallel to the inner sides of the cover plates.

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 Representations for which protection here is claimed. The subdivision of the application in individual sections as well as intermediate headings do not limit the statements made thereunder in their generality.

Brief description of the drawings

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

1 an oblique view of an impeller of a pump according to the invention including a linear slide used for the production,

2 a section through the impeller 1 .

3 a plan view of the impeller 1 with removed cover plate,

4 a side view of the arrangement 1 and

5 a pump according to the invention with an impeller described here.

Detailed description of the embodiments

In 5 is very schematically a pump 10 shown, which is designed as a radial impeller pump. In a pump chamber, it has an impeller 11 which sucks fluid through a central suction and radiates in the radial direction in the pump chamber. From there, the fluid can emerge after a few revolutions within the pump chamber from an outlet. This is known from the prior art. The impeller 11 is specially designed for this pump, as from the 1 to 4 becomes clear.

In the oblique view according to 1 has the impeller 11 an upper cover disk 13 and a lower cover disk 20 on. The upper cover disc 13 has a central suction opening 14 on. Concentric to this, the lower cover plate 20 an axle mount 21 on, with the impeller 11 is attached to an axis of a pump motor. The trained as a rounded survey axle 21 also deflects the sucked fluid radially outward. How out 1 It can be seen, is the top of the upper cover plate 13 flat except for a slightly thicker edge of the intake 14 , as well as above all 4 becomes clear. The same applies to the underside of the lower cover plate 20 and in both cases this does not have to be the case.

But the same is a subpage 16 the upper cover disc 13 flat or plane, in particular plane-parallel to the top. Except for a central area with the axle 21 this also applies to a top 23 the lower cover disc 20 , In particular, bottom are 16 and top 23 also in turn plane-parallel to each other except for the area of the axle 21 ,

The impeller 11 has five blades 27 on whose form or course mainly from the 2 and 3 can be seen. The shovels 27 are each identically formed or shaped. An outer edge 28a the blades 27 agrees with an outer edge 18 the upper cover disc 13 and an outer edge 24 the lower cover disc 20 , The outer edge 28a the blades 27 runs very inclined or oblique, see in particular the 1 and 4 , The initial angle to the lower cover plate 20 is about 20 °, in the upper area to the upper cover disk 13 There are more, and about 40 °.

In the longitudinal course of the blade 27 radially inward, the inclination decreases more and more, until it reaches an inner edge 28b almost perpendicular to the shrouds 13 and 20 and parallel to the longitudinal central axis of the pump or to the axis of rotation of the impeller 11 run. The inner edge 28b the blades 27 is located approximately where the slowly rising axle 21 starts.

Furthermore, the blades are 27 evenly spaced or evenly distributed. From the side view according to 4 It can be seen that the slope on the outer edge 28a the blades 27 always increasing, so strictly monotone. From the top view 3 It can be seen that a curvature of the blades 27 also increases from outside to inside, albeit only slightly.

In itself, such an impeller could 11 to be formed as desired in production of several parts with such in the longitudinal course in their inclination changing blades, since a production example, in plastic injection molding is very variable. In particular, if a separate upper cover plate is applied to the blades, for example glued, the upper cover plate and the lower cover plate could also be curved, as is known from other impellers in similar pumps, see for example the EP 2150162 A ,

However, in order to enable a one-piece design and manufacture and to avoid costly, expensive and vulnerable curve slide, at least the bottom 16 the upper cover disc 13 and the top 23 the lower cover disc 20 be plane-parallel to each other or evenly expand from the inside out, in each case in the radial direction. So you can not be curved as in the aforementioned prior art.

In such a trained impeller 11 can be used to produce a linear slide 30 can be used, as shown in the figures, or there are five such linear slides are used. The sliding direction S is shown. A form side 31 that in the 3 and 4 pointing to the right, is exactly the same as it is in 3 the lower cover disc 20 towards and in the direction of rotation facing side of the blades 27 equivalent. A scoop area 33 on the form side 31 exactly corresponds to this side of the blade 27 , This is followed by an interior area 34 on, so to speak to the axle 21 in each case the inner edges 28b the blades 27 Are defined. The axle mount 21 itself is produced by another slider, which in the 3 retracted into the drawing plane.

Another scoop area 33 ' on the linear slide 30 forms at the next blade in the circumferential direction 27 the counter to the direction of rotation facing side of the blade 27 , which therefore points to the previously described blade.

Through the impeller 11 With the differently inclined blades in the longitudinal direction very good conveying properties of the impeller can be achieved. A desired and very advantageous one-piece production is achieved by the plane-parallel cover plates or the plane-parallel, mutually facing sides of the cover plates, and the illustrated and described linear slide. Thus, even if the mold for the impeller is somewhat more expensive, the actual manufacturing process by plastic injection molding is well controlled and leads to good properties of the impeller. It's still a lot easier than realizing with cam pushers.

Claims (12)

Pump, in particular for household appliances such as dishwashers or washing machines, with an impeller for conveying fluid, wherein the pump with the impeller is designed for a function as a centrifugal pump with central axial suction and radial outlet of the fluid to be delivered from the impeller, wherein the impeller Upper cover plate and a lower cover plate and a plurality of intermediate blades, characterized in that the blades are less inclined in the radially inner region relative to the longitudinal center axis of the pump than in the radially outer region. Pump according to claim 1, characterized in that the blades are increasingly inclined in their course from the radially inner region to the radially outer region or obliquely, wherein they preferably extend in the radially inner region substantially in the axial direction of the pump parallel to the axis of rotation of the impeller and thus stand upright. Pump according to claim 1 or 2, characterized in that the inclination of the blades is designed such that the blades are inclined towards the upper cover disk in the direction of rotation or inclined. Pump according to one of the preceding claims, characterized in that the change in inclination is monotonically increasing from radially inward to radially outward, wherein it is preferably increasing steadily or strictly monotonically, in particular increasing approximately uniformly. Pump according to one of the preceding claims, characterized in that a maximum angle of inclination of the blades in the radially outer region is less than 75 ° to the axis of rotation, preferably between 45 ° and 70 °. Pump according to one of the preceding claims, characterized in that the blades are curved in their longitudinal course from radially inward to outward against the direction of rotation, are preferably uniformly curved. Pump according to one of the preceding claims, characterized in that the impeller has three to eight blades, preferably four to six blades. Pump according to one of the preceding claims, characterized in that centrally on the lower cover plate of the impeller, a protruding projection is arranged, which preferably projects beyond the blades, wherein the blades extend to just before the projection. Pump according to one of the preceding claims, characterized in that the blades and the cover plates are made integrally or in one piece, in particular the entire impeller, preferably in plastic injection molding. A method of manufacturing an impeller for a pump according to any one of the preceding claims, wherein the impeller is made by injection molding, wherein only linear slides are moved into areas between the later blades of the impeller along a plane perpendicular to the axis of rotation of the impeller. A method according to claim 10, characterized in that the linear slide for the blades are moved from radially outside all substantially in the same plane. A method according to claim 10 or 11, characterized in that at least one further linear slide along the later axis of rotation of the impeller or in the axial direction is retracted, preferably through the upper cover plate in the direction of the lower cover plate to the central region of the impeller or to the form radially inner region of the blades.

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