Dishwasher comprising at least one fan impeller in the dishwashing compartment

Abstract

A dishwasher, in particular household dishwasher, includes a dishwasher cavity for receiving an item to be washed, a rotatable fan wheel arranged in the dishwasher cavity and configured to draw in air and to blow out the air, and a motor operably connected to the fan wheel and operating at a rotational speed which is variable over time.

Claims

1. A household dishwasher comprising: a dishwasher cavity for receiving items to be washed; a plurality of rotatable fan wheels held on and sharing a common frame disposed below and in proximity to an upper ceiling of the dishwasher cavity, said plurality of rotatable fan wheels configured to draw in air and to blow out the air over a top portion of the items to be washed; and a separate motor operably connected to each of the plurality of rotatable fan wheels and operating at a rotational speed which is variable over time, wherein each motor is configured to operate in a continuous operation at a rotational speed of less than 5,000 revolutions per minute during a program phase, and is configured to also operate in a boost operation at a higher rotational speed in a range of 5,000 to 12,000 revolutions per minute during a blowing-off phase than during the continuous operation, wherein the boost operation that is carried out during the blowing-off phase occurs before the continuous operation, and wherein during operation of each motor in the boost operation during the blowing-off phase, the plurality of rotatable fan wheels blow out air over the top portion of the items to be washed at such a velocity to blow out any water puddles on the top portion of the items to be washed over respective edges of the item to be washed.

2. The household dishwasher of claim 1, wherein each motor is an electronically commutated, permanent magnet-excited synchronous motor.

3. The household dishwasher of claim 1, wherein each motor is configured to operate in a rotational speed range from 1,500 revolutions to 12,000 revolutions per minute.

4. The household dishwasher of claim 1, wherein the boost operation lasts less than 120 seconds.

5. The household dishwasher of claim 1, wherein the rotational speed of each motor during the blowing-off phase is at least 20% greater than the rotational speed of each motor during the continuous operation which follows in time.

6. The household dishwasher of claim 1, wherein each motor is configured for measurement of a motor current and determination of a blocking of a corresponding fan wheel.

7. The household dishwasher of claim 1, wherein each motor is configured for control or regulation to a desired rotational speed in a sensorless manner.

8. The household dishwasher of claim 1, wherein each motor is arranged above a corresponding fan wheel.

9. The household dishwasher of claim 1, wherein each motor has an axial extent of less than four centimeters.

10. The household dishwasher of claim 1, wherein each motor and a corresponding fan wheel have an overall structural height which is less than five centimeters.

11. The household dishwasher of claim 1, wherein the plurality of rotatable fan wheels is assigned to a cutlery drawer and/or a basket.

12. The household dishwasher of claim 1, wherein the plurality of fan wheels comprises four fan wheels held on the shared frame in a square-shaped arrangement when viewed from above.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention and its advantageous embodiments and developments as well as the advantages thereof are described below in greater detail with reference to drawings illustrating exemplary embodiments. These are schematic principle sketches in which:

(2) FIG. 1 shows a schematic perspective view obliquely from the front of an advantageous embodiment of a dishwasher, with a door on the front side here and a dishwasher cavity inside,

(3) FIG. 2 shows a side view of an exemplary dishwasher cavity with two loading units filled with items to be washed and with a plurality of fan wheels in the upper region, which are able to apply air to the dishwasher cavity,

(4) FIG. 3 shows the dishwasher cavity in a view from the front,

(5) FIG. 4 shows a detailed view of a fan wheel with a drive motor therefor situated vertically above it, and

(6) FIG. 5 shows a top view of the fan wheels arranged above, which here by way of example are held on a shared frame in a square-shaped arrangement.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

(7) In FIGS. 1 to 5, corresponding parts are provided with the same reference characters. Only those elements of a household dishwasher are described and provided with reference characters that are necessary to the understanding of the invention.

(8) The dishwasher 1 schematically represented in FIG. 1 is a household dishwasher. It has, as an element of an appliance body 5 which is partially open or closed to the outside, which is often also referred to as a carcass, a dishwasher cavity 2 for receiving items to be washed and treated such as dishware, pots, cutlery, glasses, cooking utensils and the like. Here, each item to be washed may be held for example in loading units 10, 11, in accordance with the drawing specifically in baskets 11 and/or a cutlery drawer 10, and what is known as washing liquor may be able to be applied thereto. Here, by way of example, two baskets 11 are arranged one above the other, and an additional cutlery drawer 10 is arranged in the upper region of the dishwasher cavity 2. This arrangement is not mandatory. In the case of bulky objects to be washed, for example, an upper basket 11 or the cutlery drawer 10 may also be removed by the customer for a specific wash cycle.

(9) Washing liquor is understood to mean fresh water or in particular water circulating during operation with or without detergent and/or rinse-aid and/or desiccant. The dishwasher cavity 2 can have an at least substantially rectangular—in particular approximately square-shaped—floor plan with a front side V facing toward a user in the operating position. Here, this front side V can form a part of a kitchen front consisting of kitchen units arranged side by side, or in the case of a free-standing appliance, can also be unrelated to further units.

(10) The dishwasher cavity 2 is able to be closed off by means of a door or flap 3, in particular on this front side V. This door 3 is shown in FIG. 1 in a partially open position, in which it is then slanted with respect to the vertical. In its closed position, on the other hand, it stands upright and is pivotable forward and downward about a lower horizontal axis in the direction of the arrow 4 according to the drawing, so that it lies at least almost horizontal in the fully opened position.

(11) On its outer and front side V which is vertical in the closed position and faces toward the user, the door 3 can be provided with a décor panel 6 in order thus to undergo a visual and/or haptic enhancement and/or an adaptation to surrounding kitchen units.

(12) The dishwasher 1 is embodied in this case as a free-standing or what is known as a partly integrated or fully integrated appliance. In the latter case, the appliance body 5 can also close substantially with the outer walls of the dishwasher cavity 2. A housing surrounding the latter on the outside can then be dispensed with. A base 12, in particular for receiving functional elements such as a recirculating pump for the washing liquor for example, can be disposed in the lower region of the dishwasher.

(13) In the exemplary embodiment according to the drawing, a control panel 8 extending in the transverse direction Q of the dishwasher is assigned to the movable door 3 in its upper region, which control panel 8 can comprise an engaging opening 7 accessible from the front side V for manually opening and/or closing the door 3. In the transverse direction Q, the dishwasher often has an extent of 45, 50 or 60 centimeters. Viewed rearward in the depth direction from the front side V, the extent often also amounts to approximately 60 centimeters. The values are not mandatory.

(14) When the door or flap 3 is closed, the dishwasher cavity 2 is delimited circumferentially by three solid vertical walls 13 and two horizontal walls 15 in total, of which one forms a ceiling (above) and a further one forms a bottom (below) of the dishwasher cavity 2. In this context, the wall 14 which is arranged toward the front side V, toward a user standing in front of the dishwasher 1, and is able to move here, forms an inner element of the movable door or flap 3.

(15) The wall 15 which forms the bottom of the dishwasher cavity 2 and delimits it substantially toward the bottom lies approximately horizontally, i.e. in parallel with an external floor B on which the dishwasher 1 stands.

(16) At least one rotatable fan wheel 17 is arranged in the dishwasher cavity 2, with which air is able to be drawn in on one side and blown out on the other, wherein the at least one fan wheel 17 is assigned a motor 18, the rotational speed of which can be varied over time.

(17) At a low rotational speed, a convection/flow is forced in the interior of the dishwasher cavity 2 or flow between the individual items to be washed. This—relatively slow-flow improves the removal of moisture on the surface of the dishware. As a result, the temperature during rinsing with rinse-aid can be reduced and thus energy can be saved.

(18) At a high rotational speed, by contrast, such high flow velocities are generated that water puddles in cup bottoms, bowl bottoms or other depressions, particularly on the top side, are blown out over the respective edge of the item of dishware. In the subsequent drying process, only the surface then has to be dried.

(19) The variation of the rotational speed may either be stored in a controller or may take place differently and adapted in each case in the form of regulation when determining drying parameters.

(20) In FIG. 5, a symmetrical arrangement of four fan wheels in a shared plane is shown by way of example. Just one large central fan wheel or also two or three fan wheels in the shared plane, possibly within a shared frame 16, would also be possible for example.

(21) The fan wheel 17 or the fan wheels by way of example may be installed close below the upper ceiling 15 of the dishwasher cavity 2 (FIGS. 2, 3) or alternatively also may lie between the loading planes 10, 11 (not shown). An upper cutlery drawer 10 is not provided in FIGS. 2 and 3. Instead, the frame 16 with the fan wheels 17 is used here. Arranged above each fan wheel 17 can be a separate motor 18 which drives it. Alternatively, a plurality of fan wheels 17 also may be able to be driven by a shared motor—not shown here.

(22) Here, the at least one motor 18 is a brushless, permanent magnet-excited synchronous motor, the rotational speed of which is simple to regulate and/or control. In particular, the motor 18 has an electronic commutation and preferably operates in a sensorless manner, but is also able to be realized with a sensor (Hall effect sensor, rotary encoder).

(23) The at least one motor 18 may for example be able to be operated in a rotational speed range between 1,500 revolutions to 12,000 revolutions per minute, so that the aforementioned various operating modes result at low and at high rotational speeds.

(24) Thus, the one or each motor 18 may be able to be operated in a continuous operation for the first operating mode, in a rotational speed range of less than 5,000 revolutions per minute during a program phase, for example the drying phase. In this rotational speed range, both volume and frequency of the motor and fan movement are pleasant in terms of acoustics. In this mode, the depicted convection support can be operated.

(25) From this rotational speed range, brief boosts into a high rotational speed range from 5,000 to 12,000 revolutions per minute are able to be carried out for the second operating mode, for example such that the brief boosts each last less than 120 seconds, preferably around 90 seconds. In this operating mode, the blowing-out of the cavities, depressions etc. can take place, which can be effected with a high air throughput and a downward flow component. The higher flow noise is acceptable due to the brief interval duration, which may be repeated a number of times, for this operating mode.

(26) A boost in the rotational speed of the motor assigned to the respective fan wheel is preferably able to be carried out during a blowing-off phase before the continuous operation following in time, wherein the rotational speed of the motor during the blowing-off phase is greater, in particular at least 20% greater, than the rotational speed of the motor during the continuous operation following in time. The blowing-off phase may preferably take place after the end of the liquid-carrying operation of the final liquid-carrying partial wash cycle, in particular rinse cycle with rinse-aid, if the recirculating pump has stopped its operation or has such a low rotational speed that washing liquid no longer travels over the one or more spray devices or, expressed more generally, liquid distribution devices, to strike the items to be washed, which have been washed and are now to be dried. The continuous operation of the motor may take place after the blowing-off phase, preferably during a temporary subsection or the entire remaining duration of the wash-cycle-concluding drying cycle of the wash cycle of a dishwashing program to be performed to support the convection in the dishwasher cavity.

(27) Additionally, a blocking of a fan wheel 17, due to an improper loading for instance, is favorably able to be detected via a measurement of the motor current of a motor 18 assigned to said fan wheel 17 in each case. A corresponding warning signal can then be output.

(28) A needs-based operation of the fan wheels 17 with a high degree of efficiency and cost advantages while adhering to safety standards is thus made possible. The quality is optimized in relation to the service life. There are also advantages in terms of wear and noise.

(29) The motor 18 for driving the fan wheel 17 shown here in detail in FIG. 4 is embodied as a wet rotor, i.e. at least the rotor 22 rotates in the wet region 26 and has a wet lubricant by way of the washing liquor. The rotor 22 rotates the shaft 19, which is rotatably mounted via a bearing assembly 21, in particular bearing sleeve, and then the winged wheel 17 via the fan wheel hub 20. The rotor 22 may in particular be formed by a ferrite ring.

(30) Furthermore, the motor 18 embodied as a wet rotor comprises what is known as a motor can 23, which is somewhat pot-shaped and separates the wet-running rotor 22 from a stator 24 held in the dry area 25.

(31) The ferrite ring, as a rotor 22, has certain emergency running properties in the motor can 23, in particular when it is formed from plastic, so that even a possible dry run, which cannot be ruled out, without lubrication by way of the washing liquor does not lead to damage in the motor 18 and this does not lead to the motor can 23 grinding through. The drive can therefore be embodied as free from a shaft sealing or other moving seal. The long-term durability is improved and wear is reduced. This emergency running property of the motor can be ensured, in particular in an improved manner, by the rotor chamber 26 being filled with water, or another fluid medium, or filling up with washing liquid during the washing operation. This is because a free, in particular liquid-filled gap remains intact between the rotor 22 and the motor can 23, without the rotor brushing against the motor can.

(32) In particular, an inner bearing sleeve 21, in particular arranged in a stationary manner, is provided for the radial bearing assembly of the shaft 19 on one side of a shaft section arranged facing away from the fan wheel and in the motor can 12. Rotatably mounted therein is the section of the shaft 19 facing away from the fan wheel 17, about which a rotor is arranged on the outside with its rotor magnets or it magnetic ring, preferably ferrite magnetic ring, preferably in a substantially concentric manner. This inner bearing sleeve 21 preferably provides a radial bearing which is continuous over the axial extent of the rotor, or in particular a twin radial bearing, or a multiple radial bearing with more than two radial bearing points for the shaft 19. It replaces a conventional rotary bearing assembly of the shaft with an A-bearing before the front end face of the rotor facing the fan wheel and with a B-bearing behind the rear end face of the rotor facing away from the fan wheel. The shaft 19 is preferably connected via a coupling element 30 of the rotor 22 in a fixed manner. The coupling element 30 is preferably embodied in the form of a sleeve with a bottom 31, i.e. in the shape of a pot. The shaft 19 stands perpendicular to the bottom 31 of the pot-shaped coupling element 30 and runs from its input opening facing the fan wheel 17 toward the center thereof. In particular, the front-side end of the shaft facing away from the fan wheel 17 (from the opening of the pot-shaped coupling element 30) is guided through a through-opening in the center of the bottom 31 of the sleeve-shaped coupling element 30 and is grasped there in a twist-proof manner. The cylindrical jacket 32, in particular circular cylindrical jacket, of the sleeve-shaped coupling element 30 preferably has a radial gap distance 33 from the outer surface of the inner bearing sleeve 21. It is preferably arranged substantially concentric with respect to the inner bearing sleeve 21. The inner bearing sleeve 21 thus plugs into the cylindrical jacket 32 of the pot-shaped coupling element 30 with a subsection facing away from the fan wheel 17, in particular with its end section facing away from the fan wheel, or with its entire extent. This results in a flat design of the drive motor 18 which is pushed in an axial direction (when viewed along the shaft). Compared to a conventional drive motor with one bearing for the shaft before and after the rotor, it is shortened in terms of its axial extent. Mounted around the outside of the circular cylindrical jacket of the sleeve-shaped coupling element are one or more permanent magnets, and these are held there. The coupling element thus forms the magnetic bearing of the rotor. In particular, a ferrite ring can be arranged at and attached to the outer circumference of the sleeve-shaped coupling element. Thus, the coupling element 30 and the one or more rotor magnets mounted on its cylindrical jacket 32, in particular permanent magnets, form the rotor or the rotor unit 22. In this context, the rotor 22 revolves around the inner bearing sleeve 21 preferably arranged in a stationary manner during rotational operation of the motor 18. The end face of the inner bearing sleeve facing away from the fan wheel (when viewed along the central axis of the shaft) forms a thrust ring for the bottom of the sleeve-shaped coupling element. It provides an axial bearing for the sleeve-shaped coupling element 30 or for the rotor unit during rotational operation of the drive motor. This results in a combined radial and axial bearing for the unit consisting of drive shaft, coupling element and one or more rotor magnets.

(33) Preferably, the material of the coupling element 30 is chosen to be different from the material of the inner bearing sleeve 21, so that the inner surface of the bottom 31 of the coupling element 30 facing the fan wheel 17 is able to slide on the end face of the inner bearing sleeve 21 facing away from the fan wheel in a largely low-friction manner, in particular on startup of the motor 18. No inadmissibly high degree of abrasion, i.e. wear, is able to occur between the bottom of the coupling element and the end face of the inner bearing sleeve, due to the favorable material combination thereof. In particular, a metal is chosen for the coupling element 30, while the inner bearing sleeve 21 is manufactured from a plastic material. A friction-reducer such as graphite, carbon, PTFE for instance can expediently be added thereto, or the bearing sleeve can be provided with an outer layer coating of a friction-reducer. A material is advantageously chosen for the shaft 19 which is different from the material of the bearing sleeve 21. In particular, it is preferably manufactured from a metal, such as stainless steel for example. This results in a very low-wear and maintenance-free bearing assembly consisting of shaft and/or rotor, which also functions reliably over many years of continuous operation and also has sufficiently favorable dry-running properties, as a dry run cannot be ruled out.

(34) This specific embodiment of the motor(s) 18 is particularly advantageously combined with the described rotational speed variations. The one or more motors 18 may be arranged axially directly above the fan wheels 17 assigned to it, so that a compact structural unit is formed from the drive motor and fan wheel in each case, which has only a very small structural height. In particular, the respective fan wheel is embodied as an axial fan. The electric motor assigned to it is embodied and/or arranged such that its shaft in particular projects vertically downward. Expediently, the fan wheel is attached to the free end of the shaft which protrudes downward. At its end facing away from the fan wheel, it is preferably only mounted on one side—as described above. If, in a liquid-carrying partial wash cycle, such as the cleaning cycle of the wash cycle of a dishwashing program to be performed, washing liquid is distributed in the interior of the dishwasher cavity by means of one or more liquid distribution devices, in particular is sprayed, then the washing liquid may possibly also reach the rotor chamber of the drive motor provided by the pot of the motor can from below, where it supplies a liquid lubrication of the shaft and/or the rotor. This may be favorable for a rotational operation of the drive motor later in time, e.g., during a blowing-off phase or the drying phase of the wash cycle.

(35) In particular, the respective drive motor 18 has an axial extent of less than four centimeters, wherein the overall structural height of the motor 18 and fan wheel 17 then favorably amounts to less than five centimeters. The restriction for the remaining loading height in the dishwasher cavity 2 is minimized as a result.

(36) The frame 16 may also be part of a loading plane 10, 11, so that the one or the plurality of fan wheel(s) 17 is/are directly assigned to a cutlery drawer 10 and/or a basket 11. The installation height is minimized as a result, and the structural outlay is low.

(37) An electrical contacting of the motors 18 can be ensured via cable conduits 27 which branch off from a central conduit 28 and are sealed.