BE1032425A1 - Drying device, in particular recirculating air drying device - Google Patents

Abstract

The invention relates to a drying device, in particular a circulating air drying device, for a dishwasher, with an intake duct (10) providing an air intake opening (11), an outlet duct (12) providing an air outlet opening (13) and a fan (14), to which the intake duct (10) on the air intake side and the outlet duct (12) on the air outlet side are fluidically connected, wherein the intake duct (10) and/or the outlet duct (12) have an overstroke (19, 21) in the form of a part-circular duct deflection (20, 22), wherein a duct (10, 12) in the region of its duct deflection (20, 22) is equipped with air guiding ribs (23, 24, 25, 26, 27) running in the duct flow direction (17), characterized in that the air guiding ribs (23, 24, 25, 26, 27) are each partially circular and arranged concentrically.

Description

Description

Drying device, in particular recirculating air drying device

The invention relates to a drying device, in particular a

Circulating air drying device for a dishwasher, with a

An intake duct providing an air intake opening, an outlet duct providing an air outlet opening and a fan to which the air intake side of the

Intake duct and the outlet duct on the air outlet side are fluidically connected, whereby the intake duct and/or the outlet duct have an overstroke in the

Design of a partially circular channel deflection, wherein a

The duct is equipped with air guide ribs running in the direction of duct flow in the area of its duct deflection.

Dishwashers in general, and those with a drying device of the type mentioned above in particular, are well known in the art, so a separate written reference is not required here. Reference is therefore made to DE 10 2008 039 898 A1 as an example.

A dishwasher, in particular a household dishwasher, of the typical design has a washing container providing a washing chamber, which

For holding items to be cleaned. In case of

In a household dishwasher, the items to be washed are in particular

Crockery and/or cutlery.

When a dishwasher is used as intended,

After washing the dishes, the dishes are dried.

Different drying processes are known in the art, including hot air drying, in which the items to be dried are exposed to previously heated drying air. The air in the washing tub of the dishwasher can be used as drying air, in which case hot air drying is

Alternatively and/or in combination with this, fresh air can also be used for drying, which comes from the air surrounding the dishwasher.

atmosphere.

Regardless of whether hot air drying is carried out using circulating air and/or fresh air, a drying device is used for air guidance and heating, which provides the appropriate air guidance and uses a fan and a

Heating element. Furthermore, temperature sensors can be provided to regulate the heating output and monitor the system.

A generic drying device for hot air drying has an intake duct on the one hand and an outlet duct on the other.

Intake duct provides an air intake opening, whereas the exhaust duct has a

When used as intended, the air outlet is

Feeding the intake duct with drying air through the air intake opening, which is then conveyed through the outlet duct to the air outlet opening. The air leaving the drying device through the air outlet opening

Drying air then enters a washing container of a dishwasher that interacts with the drying device. ı5 For the purpose of conveying the drying air, the drying device has a

Blower. The intake duct on the air intake side and the exhaust duct on the air outlet side are fluidically connected to this blower.

To heat the drying air, the drying device also has a heating element. This is typically located in the outlet duct, meaning that the air drawn in by the fan passes through the heating element before leaving the drying device through the air outlet opening.

When a dishwasher is used as intended,

Splash water from the washing container can enter the drying device through the air outlet opening and/or the air intake opening. To prevent this, a duct has a so-called overstroke, typically in the form of a partially circular duct deflection. This overstroke extends from the duct-side opening upwards in the vertical direction, so that any water spraying into the duct can flow back into the washing container via the duct-side opening due to gravity. This is advantageous.

This prevents any flushing water flowing into the sewer from flowing directly into

Direction of the fan connected to the duct.

However, such an overlift intended for the purpose of water retention brings the

The disadvantage is that, when used as intended, pressure losses occur within the drying air passing through such an overstroke. To minimize such pressure losses, it is known from the prior art to

Air guide ribs are provided that are aligned in the direction of flow through the duct. The duct is equipped with such air guide ribs in the area of its channel deflection. Such air guide ribs are known, for example, from the aforementioned DE 10 2008 039 898 A1.

Although the construction known from the state of the art is used in everyday

Although this has proven itself in practical use, there is still room for improvement. The aim is, in particular, to further minimize the pressure loss associated with the necessary overstroke in the air flow passing through the overstroke. It is therefore the object of the invention to provide a drying device of the type mentioned at the outset.

Art constructively to further develop it so that in the intended

In this case, an air flow through the ducts of the drying device is permitted which is subject to the lowest possible pressure loss and, at the same time, a flow which is as uniform as possible.

To achieve this object, the invention proposes a drying device of the type mentioned at the outset, which is characterized in that the

Air guide ribs are each partially circular and arranged concentrically.

The symmetrical design of the air guide ribs provided by the invention prevents abrupt deflection of the air flow in the area of the overstroke, i.e., in the area of the partially circular duct deflection. The air guide ribs are partially circular and thus, in terms of their geometric design, adapted to the partially circular duct deflection. The air guide ribs are arranged concentrically, i.e., symmetrically around a common center point.

Abrupt flow deflections are particularly critical because they result in a massive flow separation, which results in a high pressure loss. As a result, only a comparatively low volume flow can be achieved. The design according to the invention provides a remedy here, since the design of the air guide ribs provided according to the invention prevents an abrupt

Flow deflection is avoided.

According to a further feature of the invention, the air guide ribs are semicircular. This design is particularly preferred when the duct has an overstroke with a semicircular duct deflection. Such a semicircular duct deflection is particularly preferred with regard to optimized protection against unwanted water penetration. In this case, the air guide ribs are adapted in their geometric design to the duct deflection, so that an optimized deflection of the flow can take place, i.e. with the lowest possible pressure loss and at the same time

Achieving the most uniform flow possible.

According to a further feature of the invention, it is provided that the radial distances between adjacent air guide ribs are of different sizes. It is therefore proposed that a first radial distance between two adjacent

The air guide ribs are dimensioned differently than the radial distance between two other adjacent air guide ribs. The air guide ribs are therefore dimensioned differently in their radial

Distance keeping not equidistant.

The channels of the drying device are due to the lack of a housing of a

The installation space provided for the dishwasher is comparatively flat.

For narrow channel deflections in comparatively flat channels,

Flow deflection either comparatively many equidistantly arranged

Air guide ribs are used so that the flow is more even after the deflection, although this results in a relatively high pressure loss. Or, instead, significantly fewer air guide ribs are used, which

Pressure loss is reduced, but significantly higher separation effects occur. The inventive design provides a remedy here because, in contrast to the prior art, the air guide ribs no longer have an equidistant radial spacing from one another, but rather a spacing that varies between two adjacent air guide ribs.

According to a particularly preferred embodiment, it is provided that the

Radial distances with increasing distance of the air guide ribs from the common

The air guide ribs therefore have a distance between them that increases from the center point outwards. This achieves low turbulence in the wake of the deflection and keeps the unavoidable pressure loss to a minimum.

Due to the spacing design between the individual air guide ribs, a comparatively narrow air flow takes place in the inner area of the deflection, where the air flow experiences the highest forces, whereas in the outer areas, where the air flow is directed towards the

The forces acting on the flow decrease and the air flow is less narrow.

This ensures that a surface that causes pressure loss is only used where its advantages outweigh the associated disadvantages. Furthermore, in the outer area, where the air guide fins have a larger surface area, fewer of these are used. This contributes to minimal pressure loss.

As a result, with the most even flow possible, a largely

Reduced pressure loss can be achieved.

According to a further feature of the invention, the growth factor

S of the increasing radial distance has a value between 1.4 and 2.2.

The growth factor S of the increasing radial distance between the air guide fins is crucial for the optimized compromise between flow control and pressure loss. As the applicant's investigations have shown, this growth factor S is preferably in the range between 1.4 and 2.2.

According to a further feature of the invention, the growth factor

S can be described with the following equation: on = 71, X NX S” with

T1! Deflection radius of the first air guide rib and 2x: Deflection radius of the first air guide rib following in radial direction

Air guide ribs, where n=n+f with

To: deflection radius and

B: Value in the range between 2mm and 12mm.

The radius of the first air guide rib in the radial direction depends on the deflection radius r9. Preferably, the distance 8 between the deflection radius 74 and

Radius 7 of the first air guide rib is between 2 mm and 12 mm. 11 According to a further feature of the invention, a trailing rib is arranged on an air guide rib facing away from the flow. This additionally contributes to reducing the formation of detachment bubbles. It is particularly preferred that a trailing rib be designed to run in a straight line and continue the associated air guide rib tangentially.

In combination with the non-equidistant distances between the individual

Air guide ribs can be extended by trailing ribs in synergistic

In this way, the scaling factor can be further increased, which allows the total number of air guide fins to be reduced. This measure not only further reduces the pressure loss, but also results in a significant

The wake area is evened out. However, the wake ribs must not be too long in order to keep the additional surface area over which the flow is carried as small as possible. A wake rib preferably has a longitudinal extension in the range of 2 mm to 20 mm.

It is preferred that the trailing ribs have a different longitudinal extension. In this context, it is further preferred that the end edges of the trailing ribs remote from the air guiding ribs are arranged on a common

Lie straight. This optimizes the previously described

Flow conditions take place with the result that the lowest possible pressure loss is achieved while at the same time the wake flow is evened out. The design according to the invention therefore leads to a significant harmonization of the flow behind the deflection, while at the same time reducing the

pressure loss, thus optimizing the two conflicting interests.

This flow optimization advantageously leads to the fact that in order to achieve the volume flow required for proper drying, less powerful

Drying fans can be used. This is not only for energy reasons

This is advantageous for many reasons, especially as it can reduce noise pollution during normal fan operation.

The pollution of the atmosphere surrounding a dishwasher can be significantly reduced, which is considered advantageous for users.

Further features and advantages of the invention will become apparent from the following

Description based on the figures.

Fig. 1 in schematic perspective view an inventive

Dishwasher;

Fig. 2 in a schematic side view the dishwasher according to Fig. 1 and

Fig. 3 shows a schematic side view of the

Drying device of the dishwasher according to Fig. 1 and 2.

Fig. 1 shows a schematic perspective view of an inventive

Dishwasher 1.

The dishwasher 1 has, in a manner known per se, a

Washing compartment 3 providing washing container 2, which is used in the intended

Use case for holding items to be cleaned.

For the purpose of hot air drying of wash items in the washing container 2, the

Dishwasher 1 via a drying device 9.

As can be seen from a summary of Figures 1 and 2 in particular, the

Drying device 9 for guiding drying air has an intake duct 10 on the one hand and an outlet duct 12 on the other hand. Furthermore, the

Drying device 9 via a blower 14, to which the intake duct 10 on the air intake side and the outlet duct 12 on the air outlet side are fluidically connected.

The fan 14 of the drying device 9 is located in the base area 18 of the

Dishwasher 1, i.e. in the vertical direction 8 below the washing container 2. The two channels, i.e. the intake channel 10 and the outlet channel 12, are arranged on the outside of the washing container 2 on a washing container side wall 4 of the washing container 2.

As can be seen in particular from the illustration in Fig. 1, the washing container 2 has two washing container side walls 4, a cover part 5, a base part 6 and a

Rear wall 16. Opposite the rear wall 16 there is a loading opening 7 through which, when used as intended, a

The washing container 2 can be loaded with wash items.

As can be seen from a synopsis of Fig. 1 and 2, the

Intake channel 10 of the drying device 9 provides an air intake opening 11.

Accordingly, the outlet channel 12 has an air outlet opening 13. Both

Openings, i.e. the air intake opening 11 and the air outlet opening 13, both open into the washing chamber 3. Accordingly, in the intended use

In this case, an air flow can take place, as shown in Fig. 2

Arrows 17 can be seen, which indicate the direction of flow.

In accordance with the illustration in Fig. 2, in the intended

When the drying device 9 is used, recirculation takes place. The fan 14 draws drying air from the washing chamber 3 through the air intake opening 11. This

Drying air passes through the intake duct 10 and through the fan 14 to the

Outlet channel 12. A heating device 15 is integrated into the outlet channel 12, by means of which the drying air passing through the outlet channel 12 is heated. The heated drying air leaves the drying device 9 via the

Outlet opening 13 provided by outlet channel 12, wherein it is returned to the rinsing chamber 3.

As can be seen from Figs. 1 to 3, both the intake duct 10 and the exhaust duct 12 each have an overstroke 19 and 21, respectively, each with a part-circular duct deflection 20 and 22, respectively.

The overflows 19 and 21 respectively serve to prevent any water entering a channel 10 or 12 via the respective opening 11 or 13 from flowing to the blower 14. Any water introduced into the channels 10 or 12 via the openings 11 or 13 can, thanks to the respective

Overstroke 19 or 21, i.e. thanks to the respective channel deflection 20 or 22 provided, does not migrate upwards against the acting force of gravity, but is rather guided under the influence of gravity through the respective associated opening 11 or 13 back into the rinsing chamber 3.

These overstrokes 19 and 21, which are provided to protect the fan 14 in particular from unwanted water ingress, bring, however, with regard to the

Drying device 9 through the channels 10 and 12 to be led ı5 drying air has the disadvantage that with regard to the air flow in the area of

Channel deflections 20 and 22 lead to unavoidable pressure losses and uneven flow. This is particularly due to the fact that the channels 10 and 12 are designed to be relatively flat due to the space constraints, as is particularly the case with the

The illustration according to Fig. 1 shows the channel deflections 20 and 22

The resulting pressure loss during normal use leads to a reduced volume flow. In order to build up the volume flow required for normal drying, a sufficiently powerful fan 14 is required.

In this case, the device generates a considerable amount of noise, which is perceived as a disadvantage by users.

One of the most important target values for flow components in general is the

Pressure loss. In addition to the component size and the flow velocity,

Deflections are a major cause of pressure loss. Very abrupt deflections are particularly critical, as they cause significant flow separation. High pressure loss results in only a low flow rate being achieved or in the need for a more powerful and therefore quieter blower.

This problem is particularly relevant for drying devices in dishwashers. The limited and often very flat space available in the housing of a dishwasher is not suitable for high

The volume flow is counterproductive. To make matters worse, the fan noise generated during operation increases significantly as the fan size decreases. Noise emission is an important target in the development of

Dishwashers. This target value is also served by the inventive

Design. Accordingly, as can be seen particularly in the illustration according to Fig. 3, air guide ribs 23, 24, 25, 26, 27 are provided, each of which is partially circular in shape. The intake duct 10 provides the air guide ribs 23 and 24, and the exhaust duct 12 provides the air guide ribs 25, 26, and 27. The air guide ribs 23 and 24 of the intake duct 10, as well as the air guide ribs 25, 26, and 27 of the exhaust duct 12, are each arranged concentrically.

As can also be seen from Fig. 3, the air guide ribs 23, 24, 25, 26, 27 are each semicircular in shape, corresponding to the respective channel deflection 20 or 22.

As can be seen from the illustration in Fig. 3, the radial distances between adjacent guide ribs are of different sizes, with the radial distances increasing with increasing distance of the air guide ribs 23, 24, 25, 26, 27 from the common

The air guide ribs 23, 24, 25, 26, and 27 are therefore not equidistant from one another; rather, the distance between two adjacent air guide ribs increases with radial distance from the respective center point. This design ensures a uniform wake flow while simultaneously minimizing pressure loss.

The growth factor S of the increasing radial distance between the air guide ribs

Is crucial for an optimized compromise between flow guidance and

Pressure loss. The growth factor S preferably has a value between 1.4 and 2.2 and can be described by the following equation:

According to a further feature of the invention, the growth factor

S can be described with the following equation:

Yan = 71, X NX S”

with

T1! Deflection radius of the first air guide rib and 2x: Deflection radius of the first air guide rib following in radial direction

Air guide ribs, where n=1n+ß with

To: deflection radius and

B: Value in the range between 2mm and 12mm.

The radius of the inner deflection depends on the deflection radius 7.

Preferably, the first distance 6 is 2 mm to 12 mm.

A further structural improvement of the concentrically arranged guide ribs is achieved by trailing ribs 28, 29, 30, 31, 32, wherein a trailing rib 28, 29, 30, 31, 32 is arranged on an air guide rib 23, 24, 25, 26, 27 facing away from the flow, as can also be seen in Fig. 3.

A trailing rib 28, 29, 30, 31, 32 is designed to run in a straight line and continues the associated air guide rib tangentially. As can be seen from the illustration in Fig. 3, the trailing rib 28 is connected to the air guide rib 23, the trailing rib 29 to the air guide rib 24, the trailing rib 30 to the air guide rib 25, the trailing rib 31 to the air guide rib 26 and the

Trailing rib 32 is assigned to the air guide rib 27. The trailing ribs 28, 29, 30, 31, 32 are designed differently with regard to their longitudinal extent, wherein the

Wake ribs 28 and 29 or 30, 31, 32 of a channel 10 or 11, respectively, with their end edges remote from the air-guiding ribs, lie on a common straight line 33 or 34. The previously described effect of a uniform wake flow with simultaneously minimized pressure loss is thereby further enhanced.

Reference numeral 1 Dishwasher 21 Overstroke 2 Washing container 22 Channel deflection 3 Washing chamber 23 Air guide rib 4 Washing container side wall 25 24 Air guide rib

5 Ceiling section 25 Air guide rib 6 Floor section 26 Air guide rib 7 Loading opening 27 Air guide rib 8 Height direction 28 Trailing rib

9 Drying device 30 29 Trailing rib 10 Intake duct 30 Trailing rib 11 Air intake opening 31 Trailing rib 12 Outlet duct 32 Trailing rib 13 Air outlet opening 33 Straight

14 Fan 35 34 Straight 15 Heating device 16 Rear wall r Deflection radius 17 Arrow (flow direction) S Growth factor 18 _ Base area B Distance

19 Overtravel n Number 20 Channel deflection

Claims (11)

Patent claims 1. Drying device, in particular a circulating air drying device, for a dishwasher, with an intake duct (10) providing an air intake opening (11), an outlet duct (12) providing an air outlet opening (13) and a fan (14), to which the intake duct (10) on the air intake side and the outlet duct (12) on the air outlet side are fluidically connected, wherein the intake duct (10) and/or the outlet duct (12) have an overstroke (19, 21) in the form of a part-circular duct deflection (20, 22), wherein a duct (10, 12) in the region of its duct deflection (20, 22) is equipped with air guiding ribs (23, 24, 25, 26, 27) running in the duct flow direction (17), characterized in that the air guiding ribs (23, 24, 25, 26, 27) Each is partially circular and arranged concentrically. 2. Drying device according to claim 1, characterized in that the air guiding ribs (23, 24, 25, 26, 27) are semicircular. 3. Drying device according to claim 1 or 2, characterized in that the radial distances between adjacent air guide ribs (23, 24, 25, 26, 27) are of different sizes. 4. Drying device according to claim 3, characterized in that the radial distances increase with increasing distance of the air guide ribs (23, 24, 25, 26, 27) from the common center. 5. Drying device according to claim 4, characterized in that the growth factor S of the increasing radial distance has a value between 1.4 and 2.2. 6. Drying device according to claim 5, characterized in that the growth factor S is calculated from θn = 71, X NX S" with T1! deflection radius of the first air guide rib and Tan; deflection radius of the air guide ribs following the first air guide rib in the radial direction, where n=n+f with To: deflection radius and B: value in the range between 2mm and 12mm. 7. Drying device according to one of the preceding claims, characterized in that a trailing rib (28, 29, 30, 31, 32) is arranged on an air guide rib (23, 24, 25, 26, 27) facing away from the flow. 8. Drying device according to claim 7, characterized in that a trailing rib (28, 29, 30, 31, 32) is designed to run in a straight line and tangentially extends the associated air guide rib (23, 24, 25, 26, 27). 9. Drying device according to claim 8, characterized in that the trailing ribs (28, 29, 30, 31, 32) have a different longitudinal extent. 10. Drying device according to claim 9, characterized in that the end edges of the trailing ribs (28, 29, 30, 31, 32) remote from the air guiding ribs lie on a common straight line (33, 34). 11. Dishwasher with a drying device according to one of the preceding claims 1 to 10.