Drying device, in particular an air circulation drying device

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

[0001] The invention relates to a drying device, in particular a circulating air drying device, for a dishwasher, having an intake duct providing an air intake opening, an outlet duct providing an air outlet opening and a fan to which the intake duct on the air intake side and the outlet duct on the air outlet side are fluidically connected, wherein the intake duct and / or the outlet duct have an overstroke in the form of a part-circular duct deflection, wherein a duct is equipped in the region of its duct deflection with air guide ribs running in the direction of duct flow.

[0002] 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.

[0003] A dishwasher, particularly a household dishwasher, of the typical design has a wash tub that provides a wash chamber and serves to hold the items to be cleaned. In the case of a household dishwasher, the items to be washed are, in particular, dishes and / or cutlery.

[0004] When a dishwasher is used as intended, the dishes are dried after cleaning. Various drying methods are known in the art, including hot-air drying, in which the dishes to be dried are exposed to previously heated drying air. The air in the dishwasher's wash tub can be used as the drying air, in which case hot-air drying takes place in recirculation mode. Alternatively and / or in combination with this, fresh air drawn from the atmosphere surrounding the dishwasher can also be used for drying.

[0005] Regardless of whether hot-air drying is carried out using recirculated air and / or fresh air, a drying device is used for air flow and heating. This device provides appropriate air ducts and is equipped with a fan and a heating element. Furthermore, temperature sensors can be provided to regulate the heating output and monitor the system.

[0006] A generic drying device for hot-air drying has an intake duct on the one hand and an outlet duct on the other. The intake duct provides an air intake opening, whereas the outlet duct has an air outlet opening. During intended use, the intake duct is supplied with drying air through the air intake opening, which is then conveyed through the outlet duct to the air outlet opening. The drying air leaving the drying device through the air outlet opening then enters a washing compartment of a dishwasher that interacts with the drying device.

[0007] The drying system is equipped with a fan to convey the drying air. The intake duct on the air intake side and the outlet duct on the air outlet side are connected to this fan.

[0008] 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.

[0009] When a dishwasher is used as intended, water spray from the wash tub can enter the drying unit through the air outlet opening and / or the air intake opening. To prevent this, a duct has a so-called overtravel, typically in the form of a partially circular duct deflector. This overtravel extends vertically upwards from the duct-side opening so that any water spraying into the duct can flow back into the wash tub via the duct-side opening due to gravity. This advantageously prevents any rinse water flowing into the duct from flowing directly towards the fan fluidically connected to the duct.

[0010] However, such an overstroke intended for the purpose of water retention has the disadvantage 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 provide air guide ribs aligned in the direction of flow through the duct. The duct is equipped with such air guide ribs in the area of ​​its duct deflection. Such air guide ribs are known, for example, from the aforementioned DE 10 2008 039 898 A1.

[0011] Although the prior art design has proven itself in everyday practical use, there is still room for improvement. In particular, the aim is to further minimize the pressure loss associated with the necessary overstroke in the air flow passing through the overstroke. Therefore, Task The invention is to further develop the design of a drying device of the type mentioned at the outset in such a way that, when used as intended, an air flow through the channels 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.

[0012] To SolutionTo 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.

[0013] The symmetrical design of the air guide ribs provided by the invention prevents an 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.

[0014] Abrupt flow deflections are particularly critical because they result in massive flow separation, resulting in 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 abrupt flow deflections.

[0015] According to a further feature of the invention, the air guide ribs are semicircular. This configuration is particularly preferred when the duct has an overflow with a semicircular duct deflection. Such a semicircular duct deflection is particularly preferred with regard to optimized protection against unwanted water ingress. In this case, the air guide ribs are geometrically adapted to the duct deflection, so that an optimized flow deflection can take place, i.e., with the lowest possible pressure loss while simultaneously achieving the most uniform flow possible.

[0016] According to a further feature of the invention, the radial spacings between adjacent air guide ribs are designed to be different. It is therefore proposed that a first radial spacing between two adjacent air guide ribs be dimensioned differently than a radial spacing between two other adjacent air guide ribs. The air guide ribs are therefore not designed to be equidistant in their radial spacing.

[0017] The ducts of the drying device are comparatively flat due to the lack of installation space provided by the housing of a dishwasher. In the case of narrow duct deflections in comparatively flat ducts, either a comparatively large number of equidistantly arranged air guide ribs can be used to deflect the flow, so that the flow after the deflection is more uniform, although this results in a relatively high pressure loss. Or, instead, significantly fewer air guide ribs can be used, which reduces the pressure loss but results in significantly higher separation effects. The design according to the invention provides a remedy here because, in a departure from the prior art, the air guide ribs no longer have an equidistant radial spacing from one another, but rather one that varies between two adjacent air guide ribs.

[0018] According to a particularly preferred embodiment, the radial spacing increases with increasing distance between the air guide ribs from the common center point. The air guide ribs therefore have a spacing between them that increases from the center point outwards. This not only achieves low turbulence in the wake of the deflection, but also keeps the unavoidable pressure loss to a minimum. Due to the inventive spacing design between the individual air guide ribs, a comparatively narrow air flow occurs in the inner region of the deflection, where the air flow experiences the greatest forces, whereas a less narrow air flow occurs in the outer regions, where the forces acting on the flow decrease. As a result, a surface that causes pressure losses is only used where its advantages more than compensate for the associated disadvantages.In addition, fewer air guide fins are used in the outer area, where they have a larger surface area. This contributes to minimal pressure loss.

[0019] As a result, pressure loss can be reduced as much as possible with the most uniform flow possible.

[0020] 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.

[0021] The growth factor S of the increasing radial distance between the air guide fins is crucial for the optimized compromise between flow guidance 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.

[0022] According to a further feature of the invention, the growth factor S can be described by the following equation: r 2 … n = r 1 × n × S n with r 1 : Deflection radius of the first air guide rib and r 2... n :Deflection radius of the air guide ribs following the first air guide rib in the radial direction, where r1=r0+β with r 0 : Deflection radius and β :Value in the range between 2mm and 12mm.

[0023] The radius of the first air guide rib in the radial direction is dependent on the deflection radius r 0. Preferably, the distance β between deflection radius r 0 and radius r 1 of the first air guide rib between 2 mm and 12 mm.

[0024] 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 separation 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.

[0025] In combination with the non-equidistant spacing between the individual air guide ribs, the scaling factor can be further increased synergistically by extending the ribs through trailing ribs, allowing a reduction in the total number of air guide ribs required. This measure not only further reduces pressure loss but also significantly evens out the wake flow area. However, the trailing ribs must not be too long in order to keep the additional surface area over which the air flows as small as possible. A trailing rib preferably has a longitudinal extension in the range of 2 mm to 20 mm.

[0026] It is preferred that the trailing ribs have different longitudinal extensions. In this context, it is further preferred that the end edges of the trailing ribs, remote from the air-guiding ribs, lie on a common straight line. This optimizes the previously described flow conditions, resulting in the lowest possible pressure loss while simultaneously homogenizing the wake flow. The inventive design thus leads to a significant harmonization of the flow behind the deflection, while simultaneously reducing the pressure loss, thus optimizing the two inherently conflicting interests.

[0027] This flow optimization advantageously allows for the use of less powerful drying fans to achieve the volume flow required for proper drying. This is not only advantageous for energy-saving reasons, but also, in particular, can reduce noise pollution during normal fan operation. The acoustic impact on the atmosphere surrounding a dishwasher can thus be significantly reduced, which is considered advantageous for users.

[0028] Further features and advantages of the invention will become apparent from the following description with reference to the figures. Fig. 1 shows a schematic perspective view of a dishwasher according to the invention; Fig. 2 shows a schematic side view of the dishwasher according to Fig. 1and Fig. 3 in a schematic side view, a section of the drying device of the dishwasher according to the Fig. 1 and 2 .

[0029] Fig. 1 shows a schematic perspective view of a dishwasher 1 according to the invention.

[0030] The dishwasher 1 has, in a manner known per se, a washing container 2 providing a washing chamber 3, which, when used as intended, serves to hold items to be cleaned.

[0031] For the purpose of hot air drying of dishes in the washing container 2, the dishwasher 1 has a drying device 9.

[0032] As can be seen from a summary of the Fig. 1 and 2The drying device 9 has an intake duct 10 on the one hand and an outlet duct 12 on the other hand for guiding drying air. Furthermore, the drying device 9 has 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 fluidly connected.

[0033] The fan 14 of the drying device 9 is arranged in the base area 18 of the dishwasher 1, ie in the vertical direction 8 below the washing container 2. The two channels, ie 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.

[0034] As can be seen particularly from the presentation after Fig. 1The washing container 2 has two washing container side walls 4, a ceiling part 5, a base part 6 and a rear wall 16. Opposite the rear wall 16 there is a loading opening 7 through which the washing container 2 can be loaded with wash items when used as intended.

[0035] As can be further seen from a summary of the Fig. 1 and 2 The intake duct 10 of the drying device 9 provides an air intake opening 11.

[0036] Accordingly, the outlet channel 12 has an air outlet opening 13. Both openings, ie the air intake opening 11 and the air outlet opening 13, both open into the washing chamber 3. Accordingly, in the intended use, an air flow can take place, as shown in Fig. 2 The arrows 17 shown here indicate the direction of flow.

[0037] In accordance with the representation according to Fig. 2 When the drying device 9 is used as intended, recirculation mode occurs. The fan 14 draws in drying air from the wash cabinet 3 through the air intake opening 11. This drying air passes through the intake duct 10 and through the fan 14 to the outlet duct 12. A heating device 15 is integrated into the outlet duct 12, by means of which the drying air passing through the outlet duct 12 is heated. The heated drying air leaves the drying device 9 through the outlet opening 13 provided by the outlet duct 12 and is returned to the wash cabinet 3.

[0038] As the Fig. 1 to 3 As can be seen, 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.

[0039] The overstrokes 19 and 21 each serve to prevent any water penetrating into a channel 10 or 12 via the respective opening 11 or 13 from flowing to the fan 14. This is because any water introduced into the channels 10 or 12 via the openings 11 or 13 cannot, thanks to the respective overstroke 19 or 21, i.e., thanks to the respective channel deflection 20 or 22 provided, migrate upwards against the acting force of gravity, but is instead guided back into the flushing chamber 3 through the respective opening 11 or 13 under the influence of gravity.

[0040] However, these overstrokes 19 and 21, which are provided to protect the fan 14 in particular from unwanted water ingress, have the disadvantage, with regard to the drying air to be guided from the drying device 9 through the ducts 10 and 12, that unavoidable pressure losses and an uneven flow occur in the area of ​​the duct deflections 20 and 22. This is particularly due to the fact that the ducts 10 and 12 are designed to be comparatively flat due to the space constraints, as is particularly evident in the illustration according to Fig. 1The pressure loss resulting from the channel deflections 20 and 22 during intended use leads to a reduced volume flow. To generate the volume flow required for proper drying, a correspondingly powerful fan 14 is required. This results in a significant noise level during intended use, which is perceived as disadvantageous by users.

[0041] One of the most important parameters for flow components in general is pressure drop. In addition to component size and flow velocity, deflections are a major cause of pressure drop. Very abrupt deflections are particularly critical, as they cause significant flow separation. High pressure drop results in only a low flow rate being achievable or in the need for a more powerful and therefore quieter blower.

[0042] This problem is particularly relevant for drying devices in dishwashers. The limited and often very shallow space available in the housing of a dishwasher is counterproductive for high volume flow. 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. The design according to the invention also serves this target. Accordingly, as shown in particular in the illustration according to Fig. 3As can be seen, 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.

[0043] How Fig. 3 As can also be seen, the air guide ribs 23, 24, 25, 26, 27 are each semicircular in shape, corresponding to the respective channel deflection 20 and 22.

[0044] As can be seen from the illustration Fig. 3Furthermore, the radial distances between adjacent guide ribs are designed to vary in size, with the radial distances increasing with the distance between the air guide ribs 23, 24, 25, 26, 27 from their respective common center point. The air guide ribs 23, 24, 25, 26, 27 are therefore not equidistant from one another; rather, the distance between two adjacent air guide ribs increases with radial distance from the respective associated center point. This design ensures a uniform wake flow while simultaneously minimizing pressure loss.

[0045] The growth factor S of the increasing radial distance between the air guide fins 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 by the following equation: r 2 … n = r 1 × n × S n with r 1 : Deflection radius of the first air guide rib and r 2... n :Deflection radius of the air guide ribs following the first air guide rib in the radial direction, where r1=r0+β with r 0 : Deflection radius and β :Value in the range between 2mm and 12mm.

[0046] The radius of the inner deflection is dependent on the deflection radius r 0. Preferably, the first distanceβ 2 mm to 12 mm in size.

[0047] A further constructive improvement of the concentrically arranged guide ribs is achieved by trailing ribs 28, 29, 30, 31, 32, whereby 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 is also Fig. 3 can be recognized.

[0048] 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 shown in the illustration according to Fig. 3As can be seen, the trailing rib 28 is assigned 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 to the air guide rib 27. The trailing ribs 28, 29, 30, 31, 32 are designed differently with regard to their longitudinal extent, with the trailing ribs 28 and 29 or 30, 31, 32 of a duct 10 or 11 lying with their end edges remote from the air guide ribs on a common straight line 33 or 34. The already described effect of a uniformed wake flow with simultaneously minimized pressure loss is thereby further enhanced. Reference symbol

[0049] 1 Dishwasher 2 Washing container 3 Washing chamber 4 Washing container side wall 5 Ceiling section 6 Floor section 7 Loading opening 8 Height direction 9 Drying device 10 Intake duct 11 Air intake opening 12 Outlet duct 13 Air outlet opening 14 Fan 15 Heating device 16 Rear wall 17 Arrow (flow direction) 18 Base area 19 Overtravel 20 Duct deflection 21 Overtravel 22 Duct deflection 23 Air guide rib 24 Air guide rib 25 Air guide rib 26 Air guide rib 27 Air guide rib 28 Trailing rib 29 Trailing rib 30 Trailing rib 31 Trailing rib 32 Trailing rib 33 Straight 34 Straight r Deflection radius S Growth factor β Distance n Number

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) and the outlet duct (12) are fluidically connected on the air intake side and the outlet duct (12) on the air outlet side, wherein the intake duct (10) and / or the outlet duct (12) have an overstroke (19, 21) in the form of a partially circular duct deflection (20, 22), wherein a duct (10, 12) is equipped in the region of its duct deflection (20, 22) with air guide ribs (23, 24, 25, 26, 27) running in the duct flow direction (17), characterized in that the air guide ribs (23, 24, 25, 26, 27) are each partially circular and arranged concentrically.

2. Drying device according to claim 1, characterized in thatthe air guide 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 r 2 … n = r 1 × n × S n with r 1: Deflection radius of the first air guide rib and r 2...n : Deflection radius of the air guide ribs following the first air guide rib in the radial direction, where r 1 = r 0 + β with r 0: deflection radius and β: 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 the associated air guide rib (23, 24, 25, 26, 27) is extended tangentially.

9. Drying device according to claim 8, characterized in that the trailing ribs (28, 29, 30, 31, 32) have a different longitudinal extension.

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.

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