EP3545812B1 - Dishwasher, in particular household dishwasher - Google Patents

Description

The invention relates to a dishwasher, in particular in the form of a household dishwasher, with a washing compartment that provides a washing chamber and is used to hold items to be washed to be cleaned, a collection pot into which the washing compartment flows fluidically, and a circulating pump that is fluidically connected to the collection pot by means of a suction line connected.

Dishwashers of the type described above are well known from the prior art, which is why separate printed evidence is not required at this point.

Dishwashers of the generic type have a washing compartment that provides a washing area. This rinsing chamber is accessible to the user via a loading opening which can be closed in a fluid-tight manner by means of a pivotably mounted rinsing chamber door. When used as intended, the washing container serves to accommodate items to be cleaned, which in the case of a household dishwasher can be, in particular, crockery, cutlery and/or the like.

In order to apply washing liquid, the so-called washing liquor, to items to be washed that are to be cleaned, the dishwasher has a spray device configured on the washing chamber side. As a rule, this spray device provides rotatably mounted spray arms, with two or three such spray arms typically being provided. In the case of intended use, the dishes to be cleaned are subjected to washing liquor by means of rotating spray arms.

For the purpose of supplying the spray arms with washing liquid, a circulating pump is provided which is fluidically connected to the collection pot on the one hand and to the spray arms on the other hand.

When used as intended, the washing liquor released by the spray device collects in the collection pot into which the washing container flows flows. In circulating operation, the circulating pump conveys the washing liquor accumulating in the collection pot to the spray arms of the spray device, from where the washing liquor is then released in the direction of the items to be washed.

The CN 201861600 U discloses a dishwasher with a washing compartment and a collection pot and a circulating pump connected thereto.

The DE 9010254 U1 and the EP 0852928 A2 disclose a dishwasher in which the circulating pump is designed as an axial pump.

Although dishwashers of the type described above have proven themselves in everyday practical use, there is a need for improvement. In particular, efforts are being made to further minimize water and energy consumption when used as intended. It is therefore the object of the invention to improve the design of a dishwasher of this type in such a way that reduced water and/or energy consumption is achieved when used as intended.

To solve this problem, a dishwasher with the features of claim 1 is proposed with the invention.

The circulating pumps typically used according to the prior art are radial pumps. In contrast to this, the invention proposes that an axial pump be used as a circulating pump.

A circulating pump designed according to the prior art as a radial pump has an impeller which draws in the washing liquor from the collection pot parallel to the pump shaft and discharges it from the pump impeller radially to the pump shaft. This flow deflection creates centrifugal forces which, in conjunction with a guide wheel typically located adjacent to the pump impeller, lead to an increase in pressure within the washing liquor. An asynchronous motor is typically used to drive the pump shaft and thus also the pump impeller carried by it, which provides a nominal speed of just under 3000 rpm.

To at such an output speed of a typically used In order to be able to supply the asynchronous motor with the pressure increase required in the intended use of the dishwasher while at the same time achieving the required volume flow, it is absolutely necessary to use a circulation pump designed as a radial pump. This is because the centrifugal forces arising in a radial pump as a result of the flow deflection ensure a corresponding increase in pressure for a volume flow required for the intended use of the dishwasher. For this reason, radial pumps are also used as circulating pumps according to the prior art, with the pressure increases usually being between 10 ⁴ and 10 ⁵ Pa, the volume flows between 10 l/min and 250 l/min and the impeller speed between 1000 rpm and 4000 rpm lie.

However, a radial pump is not without disadvantage for use in a dishwasher. Thus, there is a disadvantage in that the guide wheel provided for increasing the pressure is, as is typical for construction, arranged on the outside around the impeller, which means that the pump has a relatively large diameter overall. A correspondingly large installation space must therefore be made available on the dishwasher side.

However, not only the space requirement is a disadvantage, but also the relatively large internal volume, also known as dead volume, due to the design. This dead volume has an influence on the water consumption that occurs when the dishwasher is used as intended, because the pump housing accommodating the impeller must be completely filled with rinsing liquor for proper operation of the pump, which rinsing liquor is not available for the actual washing process.

After a wash program has ended, the used wash water must be pumped out. Due to the dead volume, however, the pump is only partially emptied when the washing liquor is pumped out. This is because the pump is typically emptied via the intake manifold. The washing liquor inside the pump below the suction port cannot be pumped out and therefore remains in the pump and is carried over to the next wash cycle. In this case, the entrained washing liquor is comparatively large in accordance with the dead volume, which is perceived as disadvantageous.

With a radial pump, the amount of rinsing water required by the design to carry it out an intended rinse cycle not only has a negative effect in terms of water consumption, but also in terms of energy. This is because the washing liquor has to be heated to carry out a wash cycle as intended, with the heating energy required for this also increasing with increasing water consumption.

There is another disadvantage. The pumping capacity of a radial pump drops if gas is trapped in the pumped liquid, as is the case, for example, with air trapped in the washing-up liquid. The reason for this is that the centrifugal forces generated during pump operation cause the rinsing liquid and air to separate, with the rinsing liquid collecting on the outside of the diffuser stage, while the air remains on the inside of the impeller. As a result, only a limited increase in pressure is possible.

To overcome the disadvantages explained above, an axial pump is used as a circulating pump instead of a radial pump, a departure from the prior art. In doing so, the disadvantage is consciously accepted that at a given speed there is a reduced increase in pressure within the washing liquor due to a lack of centrifugal force.

In a dishwasher of the generic type, the washing compartment opens into a collecting pot. The rinsing liquid sprayed by the spray device when used as intended collects in the collection pot, from where it is fed to the circulating pump. The amount of rinsing water required for continuous and stable pump operation also depends, among other things, on the suction depth of the circulating pump. For this reason, it is also preferred to arrange the circulating pump as low as possible in the available installation space, with the installation space being limited at the bottom by the so-called floor pan.

The circulating pump designed according to the invention as an axial pump requires a comparatively small installation space in contrast to a radial pump serving as a circulating pump. This has the advantage that the suction depth can be greater in a circulating pump designed as an axial pump than in a comparable radial pump. In contrast to a radial pump, the flow in the impeller of an axial pump is axial on both the inlet and outlet sides, i.e. parallel to the pump shaft. An axial pump therefore does not work according to the centrifugal principle, which is why the guide wheel is not arranged around the outside of the impeller, but is positioned behind it in the conveying direction. As a result, this results in a reduced pump diameter, which in turn allows the pump connection to the collection pot to be moved further down in the direction of the floor pan, which leads to an increased suction depth compared to the prior art.

The increase in suction depth achieved with the configuration according to the invention results in reduced water consumption compared to the prior art. For proper pump operation, only a reduced amount of water is required due to the increased suction depth. This effect is also supported in a synergetic manner by the fact that an axial pump, in contrast to a radial pump, is not susceptible to air inclusions in the washing liquor. The air pockets taken up by the washing liquor as a result of bubbling in the collection pot are harmless for proper operation of the circulating pump designed as an axial pump, in contrast to a radial pump used as a circulating pump, which makes it possible for the liquid level that is set in the collection pot in the intended application to pass through to be able to reduce the use of washing liquor even further.

The configuration according to the invention therefore makes it structurally possible to reduce the minimum amount of water required for proper washing operation, which not only reduces water consumption, but also reduces the thermal energy required to heat the washing liquor to a target temperature that is desirable to be reached during washing operation.

When a dishwasher is used as intended, a typical operating point is, for example, a volume flow of 40 l/min delivered by the pump, and this at a pressure increase of 30,000 Pa. At a speed that is unchanged compared to operation of a radial pump, such values cannot be achieved with an axial pump, since the hydraulic efficiency of an axial pump at a speed typical of a radial pump is below that of a radial pump. It is therefore proposed with the invention that the circulating pump designed as an axial pump is designed for an impeller speed of >10000 rpm, preferably >11000 rpm and even more preferably >12000 rpm. It is such a use of an axial pump as a circulation pump without loss of efficiency compared to A radial pump may be used as a circulation pump. The impeller speed is preferably chosen so that the specific speed of the circulating pump, also known as the wheel shape index, is >120, preferably >125, even more preferably >130.

The asynchronous motors used according to the prior art are not suitable for achieving an impeller speed of >10,000 rpm or a specific speed of >120. It is therefore proposed with the invention according to a further feature that the circulating pump designed as an axial pump interacts with a synchronous motor, in particular a brushless direct current motor or preferably an electronically commutated synchronous motor. Such a drive motor provides the advantage of a high speed, and at the same time a comparatively small size. In combination with the axial pump, which is smaller than a radial pump, the inventive design synergistically results in an overall more compact design of the pump-motor arrangement, so that overall less installation space is required for the intended accommodation within the dishwasher.

In order to achieve the aforementioned operating point of 40 l/min with a pressure increase of 30,000 Pa with a circulating pump designed as an axial pump according to the invention, the impeller speed should be selected at around 12,000 rpm, for example, in which case an impeller shape index of 134 results.

If one compares the housing dimensions of a radial pump with those of an axial pump, which are required to achieve the working point mentioned above by way of example, the housing dimensions for the axial pump are significantly reduced. The housing diameter of a corresponding radial pump is around 100 mm, whereas the housing diameter of an axial pump is only around 30 mm. This reduction in the pump housing diameter achieved with the configuration according to the invention in contrast to the prior art can advantageously be used to increase the suction depth of the circulating pump, with the result that the water consumption of the dishwasher is significantly reduced. Because the circulating pump designed as an axial pump can, in contrast to a circulating pump designed as a radial pump, because of the reduced housing dimensions in the existing Space of the dishwasher are positioned deeper, which increases the suction depth of the pump. For example, the suction depth of a circulating pump designed as a radial pump is approximately 70 mm. An axial pump with the same delivery capacity and pressure increase enables the suction depth to be increased by around 35mm to 105mm, which results in a considerable reduction in water consumption when the dishwasher is used as intended. The configuration according to the invention therefore results in reduced water consumption while at the same time saving energy, without sacrificing efficiency.

Another advantage of the axial pump is that the housing diameter is usually not larger than the diameter of the suction port on the suction side. Since the pump is emptied via the suction nozzle when pumping out, the pump housing can be completely emptied so that no washing liquid is carried over to the next wash cycle.

The reduced size of the pump housing in an axial pump compared to a radial pump also has the advantage of a reduced dead volume. This also has a positive effect on water consumption.

For the intended execution of a rinsing process, it is also advantageous that a circulating pump designed as an axial pump can convey foamy, i.e. gaseous, rinsing liquor without loss of efficiency.

Another advantage of the axial pump is that the axial impeller is less sensitive to dirt or blockages. While a cover disk is required for a radial pump, the impeller of the circulating pump designed as an axial pump can preferably be designed without cover disks, whereby the blade channel is open so that fibrous dirt can slip from the blade noses into the housing gap. There it is then, if necessary, comminuted and conveyed onward, so that an imbalance or a drop in the conveying pressure cannot occur.

There are also advantages with regard to the drive motor interacting with an axial pump. In principle, axial pumps work at a comparable hydraulic operating point at a higher speed than radial pumps. At the same Shaft power, the torque is inversely proportional to the speed and is therefore significantly lower. However, since the size of motors does not depend on the power but on the torque, drive motors for axial pumps can be dimensioned much smaller.

Another major advantage of an axial pump compared to a radial pump is that an axial pump can be reversed in the direction of rotation of the impeller, which leads to a reversal of the conveying direction of the washing liquor. Such a reversal of the conveying direction is not possible with radial pumps due to the centrifugal force principle used in radial pumps. In this case, the possibility of reversing the conveying direction provided by an axial pump can be used in particular to bring about a return of the washing liquor, for example for automated filter backwashing.

According to a further feature of the invention, it is provided that the circulation pump is carried by a base pan and has an axial impeller arranged on a motor-driven shaft, the shaft, which is preferably aligned parallel or essentially parallel to the base pan, or the axis of the axial impeller in one Distance of 10 mm to 50 mm, preferably from 15 mm to 40 mm, more preferably from 20 mm to 30 mm is arranged to the floor pan.

With a radial pump, due to the comparatively large pump housing, it is not possible to arrange the shaft that drives the impeller during operation so close to the floor pan. The construction according to the invention therefore makes it possible to realize an increased suction depth of the pump, which brings about the advantages already described above.

In this context, it is also proposed that the impeller be arranged within a pump housing, with the intake line having an inside diameter of 20 mm to 80 mm, preferably 25 mm to 60 mm, even more preferably 30 mm to 50 mm. In this case, the suction line preferably transitions into the suction connector of the pump without or at least substantially changing the diameter. The pump housing adjoining the intake port preferably has dimensions that are identical or almost identical to the intake port, ie it represents one to the intake port and preferably also identical or at least almost identical inner diameter to the intake line. As a result, the dead volume is significantly reduced compared to a radial pump. Furthermore, a complete emptying of the pump is possible. Last but not least, the smaller design compared to a radial pump makes it possible to increase the suction depth compared to a radial pump, as has already been described above.

With the configuration according to the invention, a constructive innovation is proposed overall, which results in reduced water and energy consumption when carrying out a washing program as intended.

Fig. 1

in rein schematischer Seitenansicht eine Geschirrspülmaschine nach der Erfindung;

Fig. 2

in rein schematischer Seitenansicht eine erfindungsgemäß als Axialpumpe ausgebildete Umwälzpumpe;

Fig. 3

die Darstellung nach Fig. 1 mit Darstellung der Pumpenansaugtiefe;

Fig. 4

die Darstellung nach Fig. 3, wobei anstelle einer Axialpumpe eine Radialpumpe gezeigt ist und

Fig. 5

in rein schematischer Seitenansicht eine Geschirrspülmaschine nach dem Stand der Technik.

Further features and advantages of the invention result from the following description based on the figures. show it

1

a purely schematic side view of a dishwasher according to the invention;

2

in a purely schematic side view of a circulating pump designed according to the invention as an axial pump;

3

the representation 1 with representation of the pump suction depth;

4

the representation 3 , where a radial pump is shown instead of an axial pump and

figure 5

a dishwasher according to the prior art in a purely schematic side view.

figure 5 shows a dishwasher 1 according to the prior art in a purely schematic side view.

The dishwasher 1 has a housing 2 that accommodates a washing container 3 . The washing compartment 3 in turn provides a washing chamber 4 for receiving items to be washed to be cleaned. The washing compartment 3 has a loading opening 16 for loading the washing compartment 4 with items to be cleaned. This loading opening 16 can be closed in a fluid-tight manner by means of a rinsing chamber door 17, the rinsing chamber door 17 being mounted such that it can rotate about a horizontally extending pivot axis.

In the intended use case, the items to be cleaned are treated with washing liquor, for which purpose the dishwasher 1 has a spray device 6 . In the exemplary embodiment shown, the spray device 6 includes an upper spray arm 7 and a lower spray arm 8.

The spray device 6 is fluidically connected by means of a supply line 11 to a circulating pump 9, by means of which the spray arms 7 and 8 of the spray device 6 are supplied with washing liquor in the case of a washing operation.

The rinsing container 3 providing the rinsing space 4 opens out with respect to the plane of the drawing figure 5 into a collection pot 5 on the underside. The circulation pump 9 is connected to this collection pot 5 by means of an intake line 10 . In terms of fluid technology, between the collection pot 5 and the washing chamber 4 there is an in figure 5 arranged not shown screening device.

The rinsing water circulated by the circulating pump 9 when used as intended travels from the collection pot 5 via the intake line 10, the circulating pump 9 and the supply line 11 in the direction of arrow 14 to the spray arms 7 and 8 of the spray device 6. From here the rinsing water is pumped in the direction of the Arrows 18 are released onto the washware to be cleaned, from which it then drips and collects again in the collection pot 5 after passing through the sieve device.

Furthermore, a waste water line 13 together with a drain pump 12 is connected to the collection pot 5 . After completion of a washing operation that has been carried out as intended, the washing liquor that is no longer required in the collection pot 5 can be pumped out by means of the drain pump 12 in the direction of arrow 15 and transferred to a sewage system, not shown in detail.

The circulation pump 9 according to the prior art is a radial pump. In contrast to this, the configuration according to the invention provides an axial pump as the circulating pump 9, as can be seen from the illustration of the dishwasher according to the invention 1 results.

As can be seen from the schematic representation 1 results, the circulating pump 9 designed as an axial pump has a pump housing 24 which, in terms of the flow diameter, is preferably seamlessly connected to the intake line 10 in terms of flow. An axial impeller 20 is arranged within the pump housing 24 . This is operatively connected to a drive motor 22 via a shaft 21. Depending on the design, the shaft 21 penetrates the pump housing 24 or the supply line 11, with a corresponding shaft seal being provided for reasons of tightness, which is not shown in detail in the figures .

2 shows the structure of the circulating pump 9 designed as an axial pump in detail. As can be seen from this representation, the pump housing 24 provides a suction side 25 and a pressure side 26 . The axial impeller 20 is arranged on the suction side, so that when the supply line 11 is fed with washing liquor during normal operation, the direction of flow corresponds to that of the arrow 29, with the result that the washing liquor delivered by the axial pump reaches the suction side 25 to the pressure side 26. In the direction of flow 29 , the axial impeller 20 is followed by a guide wheel 27 which is fixedly arranged on a hollow shaft 28 . The hollow shaft 28 accommodates the drive shaft 21 which is used for the operative connection between the motor 22 and the axial impeller 20 .

In contrast to a radial pump, an axial pump does not work according to the principle of centrifugal force, which allows the pumping direction of the axial pump to be changed by reversing the direction of rotation of the impeller. The direction of flow 29 can therefore be reversed if necessary by reversing the direction of rotation of the impeller, in which case the pressure side 26 then becomes the suction side and the suction side 25 becomes the pressure side. Such a reversal of the conveying direction can be used, for example, to be able to backwash a screening device located in the collection pot 5 for the purpose of automatic cleaning.

In contrast to a radial pump, the pump housing of an axial pump is much smaller than the pump housing of a radial pump with the same degree of efficiency. This factual connection results from the representations according to the Figures 3 and 4 , whereby 3 an axial pump and 4 shows a radial pump.

The housing 2 of a dishwasher 1 includes the bottom side with the so-called Bottom pan 19, also called bottom plate, from. The distance A _B between the washing container floor 23 determines the installation space available on the peripheral side of the collection pot 5 . The suction depth of the axial pump A _A ( 3 ) or the suction depth of the radial pump A _R ( 4 ) results as the distance between the washing tank floor 23 and the axis of rotation of the axial impeller 20 ( 3 ) or the axis of rotation of the radial impeller 30 ( 4 ). The shaft 21 driving the axial impeller 20 or the radial impeller 30 is aligned parallel to the floor pan 19 . The distance A between the shaft 21 and the floor pan 19 is the difference between the installation space height _AB and the suction depth A _A with respect to the axial pump and A _R with respect to the radial pump. As can be seen from a comparison of Figures 3 and 4 results, the suction depth of an axial pump is significantly increased compared to the suction depth of a radial pump, which also results in a reduced distance A between the shaft 21 and the floor pan 19 .

The increased suction depth in an axial pump compared to a radial pump results from the fact that the dimensions of the pump housing of an axial pump are significantly reduced compared to those of a pump housing of a radial pump. It is therefore permitted to position the axial pump lower in the available installation space, i.e. to reduce the distance A between the axis of rotation of the drive shaft and the floor pan 19 and thus to increase the distance to the flushing tank floor 23, i.e. to increase the suction depth of the pump. In order to achieve the operating points to be achieved by the circulating pump 9 when the dishwasher is operating as intended, the motor 22 in an axial pump rotates at a higher speed than in a radial pump, for example at 12000 rpm in contrast to a typical radial pump speed of 3500 rpm, for example. at least

The inventive use of an axial pump as a circulating pump instead of a radial pump known from the prior art provides a number of advantages. Above all, it is advantageous that the pump housing of an axial pump is dimensioned smaller than the pump housing of a radial pump with the same degree of efficiency. The configuration according to the invention therefore makes it possible to arrange the pump deeper in the available installation space of the dishwasher, ie to form a greater suction depth. As a result, reduced water consumption and also lower energy consumption can be realized. The reduced energy consumption results in particular from the fact that less heating energy has to be expended due to the reduced water consumption.

Another advantage of the axial pump is that the dead volume is reduced compared to the radial pump and that it is also possible to allow the pump to be completely emptied in the event of pumping out, so that the amount of washing liquor that is carried over to the next washing step is minimized.

Furthermore, an axial pump enables any sieves in the collection pot to be automatically cleaned by backwashing, because an axial pump, in contrast to a radial pump, allows you to reverse the direction of rotation of the impeller by reversing the direction of rotation of the impeller.

Reference sign

1

dishwasher

2

Housing

3

flush tank

4

dishwashing room

5

collection pot

6

spray device

7

spray arm

8th

spray arm

9

circulation pump

10

intake line

11

supply line

12

drain pump

13

sewer line

14

Arrow

15

Arrow

16

loading opening

17

scullery door

18

Arrow

19

floor pan

20

axial impeller

21

Wave

22

engine

23

rinsing tank floor

24

pump housing

25

suction side

26

pressure side

27

idler wheel

28

hollow shaft

29

flow direction

30

centrifugal impeller

Claims (9)

1. Dishwasher, in particular a domestic dishwasher, comprising a housing (2), a washing container (3), which is received by the housing (2) and provides a washing chamber (4) and is intended to receive washware to be cleaned, a collection pot (5), into which the washing container (3) fluidically opens, a circulating pump (9) designed as an axial pump which is fluidically connected to the collection pot (5) by means of a suction line (10), characterised in that

   the housing (2) terminates at the bottom with a base trough (19), the circulating pump (9) being supported by the base trough (19) and having an axial impeller (20) arranged on a motor-driven shaft (21) which is oriented in parallel or substantially in parallel with the base trough (19),

   and the shaft (21) being arranged at a distance (A) of 10 mm to 50 mm from the base trough (19), at least in the region of the axial impeller (20),
   and/or

   the suction depth (A_A), which results from the distance between the base (23) of the washing container (3) and the axis of rotation of the axial impeller (20), of the circulating pump (9) being 80% to 90% of the distance (A_B) between the base (23) of the washing container (3) and the base trough (19).
2. Dishwasher according to claim 1,
   characterised in that
   the shaft (21), at least in the region of the axial impeller (20), is arranged at a distance (A) of 15 mm to 40 mm, even more preferably of 20 mm to 30 mm, from the base trough (19).
3. Dishwasher according to any of the preceding claims,
   characterised in that
   the axial impeller (20) is arranged within a pump housing (24), the pump housing having an internal diameter of 20 mm to 80 mm, more preferably of 25 mm to 60 mm, even more preferably of 30 mm to 50 mm.
4. Dishwasher according to any of the preceding claims,
   characterised in that
   the circulating pump (9) is designed for an impeller speed of > 10,000 rpm, preferably of > 11,000 rpm, even more preferably of > 12,000 rpm.
5. Dishwasher according to any of the preceding claims,
   characterised in that
   the circulating pump (9) is designed for a specific speed of > 120, preferably of > 125, even more preferably of > 130.
6. Dishwasher according to any of the preceding claims,
   characterised by
   a synchronous motor (22) interacting with the circulating pump (9), in particular a brushless DC motor or an electronically commutated synchronous motor.
7. Dishwasher according to any of the preceding claims,
   characterised in that
   the suction depth (A_A) of the circulating pump (9) is between 120 mm and 80 mm, preferably between 110 mm and 100 mm, even more preferably is 105 mm.
8. Dishwasher according to any of the preceding claims,
   characterised in that
   the pump housing (24) has a suction nozzle which is fluidically connected to the suction line (10), the throughflow diameters of the pump housing (24) and suction nozzles being equal in size.
9. Dishwasher according to any of the preceding claims,
   characterised in that
   the impeller of the circulating pump (9) is designed to be free of cover plates.

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