EP2812581B1 - Pump with integrated heater - Google Patents

Description

The invention relates to a pump, as it can be used in particular for a water-conducting household appliance such as a dishwasher or a washing machine. Furthermore, the invention relates to a method for heating an aforementioned pump according to the invention.

For example, from the DE 102007017271 A1 is a generic pump known.

From the JP S58-72699 A Another generic pump is known. This has, on a heat-conducting element on a pump chamber cover, a heating element applied spirally around the heat-conducting element. This allows the water in the pump chamber to be heated.

Task and solution

The invention has for its object to provide a pump mentioned above and a corresponding method for heating a pump with which problems of the prior art can be avoided, in particular with regard to calcification of a heated Pumpenkammerwandung, at the same time the best possible heat coupling into the pumped liquid.

This object is achieved by a pump with the features of claim 1 and a method for heating a pump with the features of claim 8. Advantageous and preferred embodiments of the invention are the subject of further claims and are explained in more detail below.

The pump is designed as an impeller pump with a central water inlet to a rotating impeller to promote water in the radial direction from the impeller into a pump chamber surrounding the impeller annular. The pump chamber is bounded on its outside by an at least partially heated Pumpenkammerwandung. Furthermore, in the end region of the pump chamber, the pump has an outlet at an axial distance from the impeller, which protrudes from the pump chamber wall, in particular in the tangential direction. Advantageously, the outlet can be axially spaced so far from the impeller that, viewed in the axial direction, it lies approximately at the height of the water inlet as an inlet.

According to the invention, heating elements are or are provided on the pump chamber wall. The heating elements have in the axial direction of the pump to the outlet toward a decreasing performance with respect to the generated or resulting area performance. This means that in regions, the heat generation or heating effect of the heating elements is reduced in the axial direction from the impeller to the outlet.

With the invention can be achieved that in the area where the water is emerging from the impeller even colder, a larger heat output can be coupled. In the then flowing in the axial flow to the outlet and in this direction becoming warmer water can not be coupled so much heating power or it may then be the risk of local overheating, which in the water to increased precipitation of contained lime odgl. can lead and is undesirable on the heating elements or the Pumpenkammerwandung itself. So local overheating points can be avoided. Above all, by a reduced overheating of the water, a calcification can be reduced to the Pumpenkammerwandung, which is generally disturbing and then in turn worsens the efficiency of heating.

Furthermore, it is possible that the area performance in the area of the pumping chamber in which the flow of the conveyed liquid is rather turbulent is higher in the lowest area of the pumping chamber close to the outlet from the impeller and in the transition to the area in which the flow then rather laminar, is less or in this area then only relatively low. This flow effect may assist the invention, but does not characterize the invention.

In the invention, the heating elements are Schichtheizelemente. They may have a constant layer thickness and preferably be thick-film heating elements. Their power density is sufficiently large.

In a further embodiment of the invention, a plurality of heating elements may be provided which extend substantially in the axial direction of the pump, in particular exactly in the axial direction. Viewed in this direction, the heaters may have nearer to the impeller a smaller width or smaller cross-sections than at their end near the outlet and toward the outlet, respectively. Due to a smaller cross-section, the heating elements generate more heat in this area or have a higher heat output. Thus, for example, the aforementioned reduction of the heating power can be made in the axial direction. In this case, it can be provided, in particular, that with individual heating elements the width or the cross section continuously increases along the axial direction towards the outlet. In this case, a thickness of the heating elements is advantageously chosen constant, so that the influence can be determined more accurately.

In an alternative basic embodiment of the invention it can be provided that the heating elements extend substantially transversely to the axial direction of the pump. In this case, they can advantageously each annularly substantially surround the pump chamber wall, for example circulate by about 300 ° and then with its two ends on connecting rails or feeder rails or the like. be connected or contacted as contacts. It can be advantageously provided that the width or the cross section of a single annular or semi-annular heating element remains the same. However, the width or the cross-section of successive heating elements in the axial direction towards the outlet increases, so that here as well the area performance of the heating on the pump chamber wall decreases in the axial direction towards the outlet. If the spacings of the heating elements in this axial direction are not too great, then a relatively continuous distribution of the area performance of the heating can be achieved, just decreasing towards the outlet.

In the aforementioned embodiment of the invention can be provided that the one heating element which is closest to the outlet, has the largest width or the largest cross-section. Thus, it can be achieved that in fact the lowest area performance of the heating is close to the outlet by arranging the single heating element with the lowest power in this area.

In a further embodiment of the invention as an additional basic alternative can be provided that the heating elements in turn extend substantially transversely to the axial direction to the outlet. As mentioned above, they can surround the pump chamber wall in a ring-like manner as described above, ie in particular not completely circulate. Here it is then provided that the distance between the heating elements increases in the axial direction toward the outlet, while in the above-described variant of the invention, the distance was advantageously the same. Thus, by means of substantially identical or identical heating elements, which are simply arranged with more distance from each other, an area-effect heating which decreases in the axial direction can likewise be achieved. As long as the distances of the heating elements are not too large, so for example, the width of the heating elements themselves exceed significantly, can through the intervening lying pump chamber wall, which usually and advantageously consists of metal as a support for the heating elements, still a good and largely continuous distribution of the area performance can be achieved. This can thus decrease substantially continuously in the axial direction to the outlet.

Of the above ring-shaped heating elements can be provided about four to twelve pieces, particularly advantageous six to ten pieces. Of the aforementioned heating elements extending essentially in the axial direction, a similar number can be provided.

The formation of the pump chamber wall of a suitable material, in particular a metal such as one of DE 198 03 506 A1 known steel for thick-film applications, as a carrier for the heating elements is known in the art. The formation of the heating elements in the thick-film process is also familiar to the person skilled in the art, and he can resort to methods known per se. The same applies to any existing insulating layers, protective layers or electrical contacts.

Advantageously, it is provided that all heating elements of the heating of the pump chamber wall are controlled simultaneously, particularly advantageously via a single supply connection.

Thus, it can thus be achieved with the invention as a heating method, that the pump chamber wall can be heated with a plurality of distributed heating elements, which advantageously cover substantially the entire pump chamber wall, although they do not cover each area directly. In the region of a pump bottom under the impeller, the pump chamber wall is heated to a greater extent, in particular at the impeller outlet, than in the region of an outlet from the pump chamber wall, which is arranged in the axial direction away from the pump bottom. In particular, this is Outlet located at most far away from the pump bottom, so almost at the other end of the pump chamber or the Pumpenkammerwandung.

A change in the heating power can be at least a factor of 1.2 to 3, advantageously 1.5 to 2.5. This applies both to the electrical heating power or area performance and to the aforementioned dimensions of the individual heating elements in terms of width or thickness or conductor cross-section.

Brief description of the drawings

Fig. 1

einen Schnitt durch eine erfindungsgemäße Pumpe mit einer rohrförmigen Heizeinrichtung mit Heizelementen auf der Außenseite,

Fig. 2 bis 8

Draufsichten auf alternative Heizeinrichtungen entsprechend Fig. 1 mit unterschiedlich ausgebildeten und verlaufenden Heizelementen.

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

Fig. 1

a section through a pump according to the invention with a tubular heater with heating elements on the outside,

Fig. 2 to 8

Top views of alternative heating according to Fig. 1 with differently shaped and extending heating elements.

Detailed description of the embodiments

In Fig. 1 a pump 11 according to the invention is shown in section, as they are of the construction essentially of the aforementioned DE 102007017271 A1 , to which reference is explicitly made in this respect, corresponds to a radial pump or impeller pump. It can be advantageously used in a dishwasher or a washing machine. The pump 11 has in the left region a pump housing 12 with inlet 13, outlet 14 and pump chamber 16. Close to a pump chamber bottom 17, a conventional impeller 18 is arranged as a rotor or impeller. It is driven by an unspecified pump motor 20. By rotation of the impeller 18 fluid at the inlet 13 is sucked in the axial direction along the dashed longitudinal center axis L of the pump 11 and then ejected from the impeller 18 in the radial direction. Then, the fluid in the pump chamber 16 is circulated or runs around and finally exits from the pump 11 at the outlet 14. For this purpose, it has an axial flow component in addition to the circulating movement component of the fluid.

The pump chamber 16 is bounded or formed to the outside substantially by a metallic support tube 24, or on the outside thereof on an insulating layer 25 heating elements 26 are provided, so that a heating device 22 is formed. The support tube 24 is sealingly arranged by means of seals or sealing rings 21 in the pump housing.

In Fig. 2 FIG. 10 is an enlarged plan view of a first embodiment of a heater 22a according to FIG Fig. 1 shown. It can be seen how 25 heating elements 26a are provided on the support tube 24 and on the outside thereof on an insulating layer. These heating elements 26a are all formed identically and extend in the direction of the axial flow component S of the water in the pump chamber 16 accordingly Fig. 1 , In this case, the heating elements 26a are not quite up to the lower and the upper edge of the support tube 24, so that this well Fig. 1 can be installed with the sealing rings 21.

The heating elements 26a face downwardly to tapered starting portions 28a, which after about one-third of the length have reached a width which they then maintain at upper end portions 30a. The thickness of the heating elements 26a, which are formed as thick-film heating elements, is the same everywhere. By reducing the width at the lower end of the starting portions 28a, which is in particular less than half of the main width, which in turn extends to the upper end portions 30a, here a strong increase in the power or the heat energy generated is achieved. A transition of the aforementioned turbulent flow of the pumped water in the pump chamber 16 outside the impeller 18 on the inside of the heater 22 in a laminar flow is indicated to the right of the heater 22a by a dashed line. However, the transition is not as sharp or abrupt as the dashed line indicates, but occupies a certain area where the flow gradually changes from turbulent to laminar.

This transition thus runs slightly above that range from which the heating elements 26a have reached a constant width or no longer change their width and thus their heating power. This means that in the area of the laminar flow, there is less surface area than in the area of the turbulent flow. In addition, the area performance in the area of the laminar flow is substantially constant in the direction of the axial flow component.

It is off Fig. 2 It can be seen that due to the tapered initial regions 28a in the lower region of the heating device 22a more heating power is provided or more heat is generated. In particular, the heating power can be at least twice as high as in the upper Area near the end portions 30a, and thus the area performance can be almost twice as well.

In the further alternative of a heater 22b according to Fig. 3 For example, the heating elements 26b are designed such that they continuously widen in their longitudinal direction along the flow direction S from lower initial regions 28b to upper end regions 30b, which in each case bear against contacts 33 on the carrier 24 and the insulating layer 25, respectively. The smallest width in the lower starting region 28b and the largest width in the upper end region 30b corresponds approximately to those of FIG Fig. 2 , In the Fig. 3 It can also be seen that in the lower region of the heating device 22b, the surface power is greater than in the upper region, the surface power, so to speak, substantially continuously decreasing along the axial flow component S, whereas in FIG Fig. 2 yes just below the dashed transition from the turbulent flow to the laminar with a jump or rather jumped.

Not shown, but for the skilled person are easily imagined other variants of the course of the width of the heating elements 26 according to the FIGS. 2 and 3 , So, instead of widening continuously, they can also get bigger and bigger. It can also be provided a combination of uniform and sudden widening. However, even broadening is considered more advantageous in terms of current flow and power generation.

In the further alternative of a heater 22c according to Fig. 4 Now, the heating elements 26c do not run along or in the direction of the axial flow component S, but perpendicular thereto, ie in the circumferential direction on the carrier tube 24. It can be seen that the heating elements 26c in the lower end are considerably narrower than the heating elements 26c at the upper end, So in the direction S, the width of the heating elements 26c increases from one to the next. The heating elements 26c according to Fig. 4 each have the same distance from each other.

Overall, the width of the lowermost heating element 26c is less than half of the uppermost heating element 26c. Thus, a decreasing heating power is also provided here by the upwardly increasing width of the heating elements 26c. It follows, similar to the heaters according to the FIGS. 2 and 3 in that the area performance in the lower area is significantly higher than in the upper area, in particular at least twice as high. The increase in the width of the heating elements 26c from bottom to top along the axial flow component S may be uniform, for example, in each case by 20% to 30%.

In another embodiment, a heating device 22d accordingly Fig. 5 six heating elements 26 are provided, as well as otherwise already in the heater 22c according to Fig. 4 , The bottom three heating elements 26d have the same width.

Above the dashed line shown transition from the turbulent to the laminar flow two heating elements 26d are provided, which are significantly wider than the lower three, in particular about twice as wide. Above this, a heating element 26d is provided, which in turn is significantly narrower, in particular approximately as narrow as the lower three heating elements 26d.

Thus, according to the heating device 22d Fig. 5 the heat output of the individual heating elements 26d and thus, due to the same distance from each other, the area performance in the lower region of the heater 22d, in turn, similar to in FIG Fig. 4 , considerably larger than in the upper area. However, it has no or only a slight change along the axial flow component S in the lower region. This change is then more abrupt above the dashed line shown, namely towards about a halving the area performance.

After reaching the upper end of the heating device 22d, the surface output then increases once more through the narrower uppermost heating element 26d, which in turn ensures a higher area output in the uppermost area. Out Fig. 1 can be seen that this is as close as possible to the outlet 14 from the pump 11, so that here again at the end trying to bring as much heat in the pumped water. Here, too, the flow can change from laminar to turbulent, so that an increased heat loss is possible.

Unlike in Fig. 4 is also in the Fig. 5 the electrical contacting of the heating elements 26d shown via the two contacts 33d. The contacts 33d are elongated strips as contact fields, advantageously made of very good electrically conductive material such as silver conductive paste or the like. All heating elements 26d are thus connected in parallel, which also applies to the embodiments of Fig. 4 . 6 and 7 applies. The heating elements 26 of the heaters 22a and 22b of FIGS. 2 and 3 were connected in series. However, also in the heaters according to the Fig. 4 to 7 Thickness and composition of the heating elements equal or constant.

In a further alternative of a heater 22e according to Fig. 6 have the respective heating elements 26e again at the same distance from each other. Two lower heating elements 26e have the same width and extend approximately to the transition shown in dashed lines zoom. Two heating elements 26e arranged above it are considerably wider, in particular approximately twice as wide. Thus, although there are only two types or widths of heating elements 26e, each with its own power. However, since again in the upper region of the heater 22e, the area performance due to the lower heating power provided is significantly smaller than in the lower region, there is also the effect of the invention in the axial direction along the flow direction S of the pump 11 to the outlet 14 toward decreasing area performance.

In Fig. 7 is a further alternative of a heater 22f shown with heating elements 26f, which in turn have all the same distance from each other. Two lower heating elements 26f correspond in width to those of the heater 22e of FIG Fig. 6 and they extend to roughly the dashed transition between turbulent and laminar flow. Above this, a wide heating element 26f is arranged, and above this again a narrow heating element 26f. In view of the above explanations, it is clear here that in the lower area, the area performance is relatively large, then in the region of the wide heating element 26f above the dashed junction shown the area performance decreases, and then up to increase again. Thus, here an effect similar to the heater 22d according to Fig. 5 be reached, which has already been explained above.

In Fig. 8 another alternative of a heater 22g is shown. Here are five equally wide heating elements 26g provided, the distance between them but each along the axial flow component S is greater, ie increases. Thus, although all heating elements 26g produce the same heat output. In any case, according to the invention, the surface power is reduced in the direction S according to the invention by the respective increasing distance from each other. This is done relatively evenly, since the distances are also, so to speak, evenly larger, for example, each increase by 20% to 30%. It can be seen that the representation of the Fig. 8 in about an inverse representation of those Fig. 4 is where the individual heating elements 26c each became uniformly wider, while the intervals between them remained the same.

Claims (9)

1. Pump (11), in particular for a water-conducting domestic appliance such as a dishwasher or a washing machine, the pump (11) being configured as an impeller pump having a central water inflow to a rotating impeller (18) for conveying the water in the radial direction out of the impeller (18) into a pump chamber (16) which surrounds the impeller (18) in a ring-like manner and is delimited on its outer side by an at least partially heated pump chamber wall, the pump (11) having an outlet (14) in the end region of the pump chamber (16) at an axial spacing from the impeller (18), in particular with an outlet (14) in the tangential direction from the pump chamber wall, wherein heating elements (26) are arranged on the pump chamber wall, wherein the heating elements are film heating elements,
   characterized in that
   the heating elements (26) are configured such that they have a decreasing output or area output in the axial direction of the pump (11) toward the outlet (14).
2. Pump (11) according to claim 1, characterized in that the heating elements (26) have a constant film thickness, preferably are thick film heating elements.
3. Pump (11) according to claim 1 or 2, characterized in that a plurality of heating elements (26) run essentially in the axial direction of the pump (11) and, in this direction, have a smaller width or smaller cross section at the start close to the impeller (18) than at the end toward the outlet (14).
4. Pump according to claim 3, characterized in that in the case of the individual heating elements (26), the width or the cross section increases continuously along the axial direction toward the outlet (14).
5. Pump (11) according to claim 1 or 2, characterized in that the heating elements (26) run essentially transversely with respect to the axial direction toward the outlet (14), in particular in each case so as to surround the pump chamber wall substantially in a ring-like manner, the width or the cross section of an individual heating element (26) remaining unchanged and the width or the cross section of successive heating elements (26) increasing in the axial direction toward the outlet (14).
6. Pump (11) according to claim 5, characterized in that the heating element (26) which is closest to the outlet (14) has the greatest width or the greatest cross section.
7. Pump (11) according to claim 1 or 2, characterized in that the heating elements (26) run substantially transversely with respect to the axial direction toward the outlet (14), in particular in each case so as to surround the pump chamber wall substantially in a ring-like manner, the spacing of the heating elements (26) from one another increasing in the axial direction toward the outlet (14).
8. Method for heating a pump (11) according to any of the preceding claims, wherein the pump (11) is an impeller pump with the pump chamber wall and a pump chamber bottom below the impeller (18), wherein the pump chamber wall is heated by way of a plurality of distributed film heating elements as heating elements (26),
   characterized in that
   the pump chamber wall is heated to a greater extent in the region of the pump chamber bottom under the impeller (18) owing to the configuration of the heating elements than in the region of the outlet (14) from the pump chamber wall in the axial direction away from the pump chamber bottom.
9. Method according to claim 8, characterized in that the change in the heating output is at least by the factor 1.2 to 3.

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