Household appliance with a drying function

Abstract

The description relates to a household appliance (1) with a drying function, comprising a housing (2) in which a rotatably mounted drum (4) which can be closed by a door (3) and which holds the material to be dried, and an electronic control system (5) are present, wherein the household appliance further comprises at least one unit (6) for generating process air and means for directing the flow of the process air and at least one measuring unit for determining the moisture content by measuring the conductivity of the material to be dried, and the measuring unit in turn comprises at least one sensor element (7) which makes contact with the material to be dried during the drying process and at least one contact element corresponding thereto. The invention can be seen in the fact that the door-side means (8) for guiding the flow of the process air is designed as a plastic injection-molded component which integrates the sensor element (7) during its production by an injection-mold process.

Description

[0001] The invention relates to a household appliance with a drying function according to the preamble of patent claim 1.

[0002] Such a household appliance with a drying function, comprising a housing in which a rotatably mounted drum, closable by a door, for holding the goods to be dried and an electronic control system, as well as a unit for generating process air and means for directing the flow of the process air and at least one measuring unit for determining the moisture content by measuring the conductivity of the goods to be dried, are present, wherein the measuring unit in turn comprises at least one sensor element in the form of an electrode, which has contact contacts with the goods to be dried during the drying process, and at least one corresponding contact element in the form of a sliding contact sliding along the outside of the drum, is already known from EP 1 914 341 A1. In this solution, several sensor elements are present on the ribs arranged inside the drum, which has the result that the sensor elements rotate with the drum.The sliding contact element located on the outside of the drum has proven to be disadvantageous in that it is subject to increased wear and tear, and the resulting grinding noise is perceived as annoying. The items to be dried in the household appliance described are laundry.

[0003] A similar design of a household appliance with a drying function is known from EP 3 269 872 A1. In this case, sensor elements, referred to in the document as conductivity sensors, are arranged on the rear and front of the rotating drum.

[0004] DE 2 839 333 A1 also describes a household appliance with a drying function featuring the features mentioned above. The special feature of the solution presented in this document, however, is that measuring electrodes are arranged at two opposite positions within the drum and connected in parallel. According to the disclosure of the document, these measuring electrodes influence a humidity-dependent control circuit.

[0005] It is well known that the means for guiding the process air flow can be manufactured as plastic injection-molded components. This production requires an injection mold whose cavity is filled with a liquid plastic to produce the means.

[0006] In the household appliances in question here, the flow of process air starts from the unit for generating the process air, which may be a fan, for example, whose airflow is heated by a heating device. A heat pump, for example, can be used as the heating device. The heated process air generated in this way is usually led from the back of the drum through flow openings in the back into the interior of the drum, where it comes into contact with the items to be dried, for example laundry, and absorbs the moisture from the items before being discharged through air outlets in the front of the drum. The process air takes the previously absorbed moisture with it and then discharges it into the environment.It has proven advantageous to design the door-side means for guiding the process air as a plastic injection-molded component, as this allows the creation of a component that is lightweight and easy to manufacture, while at the same time optimizing the flow of the process air.

[0007] What all solutions known from the state of the art have in common is that the sensor elements required to determine the moisture content of the material to be dried usually have to be installed in a complex manner and are usually attached to the drum, which has so far been done using an ultrasonic welding process or other material-locking connections as well as with the help of screws or rivets, so that a not inconsiderable installation effort is required in each case.

[0008] The invention therefore addresses the problem of providing a household appliance with a drying function in which the sensor element required to determine the residual moisture of the goods to be dried can be arranged more simply and thus more cost-effectively in the household appliance, so that the assembly effort for this is considerably reduced or no assembly effort is required at all.

[0009] According to the invention, this problem is solved by a household appliance with a drying function having the features of patent claim 1. Advantageous embodiments and further developments of the invention emerge from the following subclaims.

[0010] A household appliance with a drying function, comprising a housing in which a rotatably mounted drum which can be closed by a door and which holds the goods to be dried and an electronic control system are present, further comprising a unit for generating process air and means for directing the flow of the process air and at least one measuring unit for determining the moisture content by measuring the conductivity of the goods to be dried, wherein the measuring unit in turn comprises at least one sensor element which has contact contacts with the goods to be dried during the drying process and at least one contact element corresponding thereto, was further developed according to the invention in that the door-side means for directing the flow of the process air is designed as a plastic injection-molded component which integrates the sensor element during its production by an injection-mold process.

[0011] With the solution according to the invention, the at least one sensor element is integrated into the door-side means for guiding the flow of the process air without requiring any additional assembly effort. This eliminates the need for components such as rivets or screws, which were previously required to secure the sensor elements. The ultrasonic welding process previously used in some household appliances to fix the sensor elements can also be completely eliminated according to the invention. According to the invention, the means for guiding the flow of the process air is produced in an injection molding tool, with the special feature being that before the actual injection molding process, the sensor element is inserted into a cavity provided for this purpose in the injection molding tool and is overmolded with the plastic during the injection molding process.This significantly simplifies the production of such a household appliance and it has also been found that errors caused by sensor elements that are not or only inadequately mounted can now be completely avoided, which leads to a reduction in scrap production.

[0012] According to a first embodiment of the invention, it is proposed that the door-side means for guiding the flow of the process air be a one-piece plastic injection-molded component. This one-piece design significantly simplifies the overall manufacturing effort for a household appliance according to the invention, because the complex flow guidance within the household appliance, by combining several channels in a one-piece plastic injection-molded component, not only reduces assembly effort but also eliminates the need for various components.

[0013] As already described in connection with the discussion of the prior art, it is also possible in a household appliance according to the invention for the contact element of the measuring unit to be arranged on the outside of the metal drum. This can also be a sliding contact arrangement. A preferred embodiment is one in which the contact element is arranged as close as possible to the rotational axis of the drum in order to reduce the length of the sliding path per rotation of the drum. This measure results in a reduction in wear, which in turn reduces the maintenance and repair effort of a household appliance according to the invention.

[0014] A further development of the invention is that the sensor element has at least one bulge that extends into the interior of the drum. The bulge formed on the sensor element ensures that, as the drum rotates, the items to be dried, such as laundry, frequently come into contact with the sensor element, which improves the accuracy of measuring the moisture content of the items to be dried. This measure also allows for significant energy savings because the household appliance switches off immediately after the items in the drum have been dried.

[0015] In order to improve the integration of the sensor element into the means for guiding the flow of the process air, which is designed as a plastic injection-molded component, it is also advantageous if, according to an embodiment of the invention, surface sections extend laterally projecting or circumferentially arranged from the bulge of the sensor element and are integrated into the plastic of the means for guiding the flow of the process air.

[0016] To determine the conductivity, the sensor element must be made of an electrically conductive material. Accordingly, the sensor element is preferably made of a metallic material, although it goes without saying that these materials are non-corrosive. The sensor element also has connecting contacts for an indirect, electrically conductive connection to the corresponding contact element. The drum of the household appliance is preferably used as the means for transmitting the electrically conductive connection, as it is made of metal and is therefore electrically conductive.

[0017] To ensure that regular contact occurs between the sensor element, and in particular its bulge, and the material to be dried, a further development of the invention is that the means for guiding the process air flow has a window in which the sensor element is accommodated. By forming a window in which the sensor element is arranged, the sensor element protrudes practically freely into the interior of the drum, thus optimizing contact with the material to be dried.

[0018] In a household appliance according to the invention, the sensor element can advantageously be, for example, between 5 and 15 cm long and between 1 and 3 cm wide. A further development involves the surface sections of the sensor element forming a border that is preferably approximately 0.5 cm wide around the sensor element.

[0019] The invention is explained in more detail below with reference to the accompanying drawings. The illustrated embodiment does not represent a limitation to the variant shown, but serves merely to explain a principle of the invention.

[0020] Identical or similar components are always designated by the same reference numerals. To illustrate the functionality of the invention, the figures show only highly simplified schematic diagrams, omitting components that are not essential to the invention. However, this does not mean that such components are not present in a solution according to the invention.

[0021] It shows: Fig. 1: a household appliance in a perspective view, Fig. 2: a means for guiding the flow of process air in a representation as a separate individual part, Fig. 3: an enlarged view of the section of the process air flow guide equipped with the sensor element and Fig. 4: a section through the sensor element and the area of ​​integration of the sensor element into the means for guiding the flow of the process air.

[0022] In the Fig. The household appliance 1 shown in Figure 1 is a tumble dryer, which can also be designed as a combination appliance comprising a washing machine and a tumble dryer. The housing 2 of the household appliance 1 contains a drum 4 which is rotatable about a rotation axis and has an interior space into which the laundry to be dried, i.e. the laundry, is introduced through a door opening. The door opening is closed by the door 3 during operation of the household appliance 1. In the illustration of Fig. 1, however, the door 3 is shown in an open state for better illustration. In a manner known per se, such a household appliance 1 has an electronic control 5, which in the Fig. 1 is only indicated by dashed lines. The electronic control unit 5 communicates with all units of the household appliance 1 and is also responsible for recording and evaluating the measured values ​​of such a household appliance 1. Inputs for controlling the operation of the household appliance 1 can be made by the user via the control unit 13 located on the front of the household appliance 1. In addition, the control unit 13 also has a display to show important operating instructions or input settings. To the side of the control unit 13 there is a compartment 14 which, in the case of a household appliance 1 designed as a washing machine with a drying function, can be used to add detergent. Behind the cover 6 located in the lower area at the front of the household appliance 1 there is also a Fig. 1 shows a unit (not shown) for generating process air, which may be, for example, a fan whose air flow is heated by a heating device. On the front side of the drum 4, a means 8 for directing the flow of process air can also be seen, which in turn has a sensor element 7 shown only by dashed lines. The means 8 for directing the flow of process air has numerous air outlet openings 16 through which the heated process air is discharged for drying the laundry. The heated process air initially flows through openings in the rear wall of the drum, absorbing the moisture from the laundry being moved by the rotation of the drum 4, and is then discharged through the aforementioned air outlet openings 16 of the means 8 for directing the flow of process air and is ultimately released into the environment along with the moisture contained in the process air.Of course, systems are also known that reuse the heat from the process air through heat recovery. This principle can also be applied to the household appliance 1 according to the invention.

[0023] From the Fig. 2, a means 8 for guiding the flow of process air is shown as a separate individual part, wherein the illustration already illustrates that this is a one-piece plastic injection-molded part. During the manufacture of the means 8 for guiding the flow of process air in a designed and suitable injection molding tool, the sensor element 7 is inserted into the injection molding tool before the actual injection molding process is carried out. As a result, the sensor element 7 is integrated into the means 8 for guiding the flow of process air directly during its manufacture, and no further assembly processes are required to arrange the sensor element 7 in its intended position for measuring the moisture content of the material to be dried, i.e., measuring the moisture content of the laundry to be dried.The means 8 for directing the process air flow has an opening 15 through which the laundry to be dried can be introduced into the drum 4 located behind it. On the underside of the means 8 for directing the process air flow, there are also numerous air passage openings 16 through which the process air is discharged in the manner already described.

[0024] The Fig. 3 and Fig. 4 each illustrate an enlarged view of the section of the means 8 for guiding the flow of the process air equipped with the sensor element 7. The exploded view of the Fig. 3 it is clear that the sensor element 7 is inserted in the direction of arrow A into a recess 17 provided for this purpose and is thereby directly integrated into the means 8 during the injection molding process required to produce the means 8 for guiding the flow of the process air. In this example, the sensor element 7 has a central measuring section which is designed as a bulge 9 and in the Fig. 4. The bulge 9 is surrounded by surface sections 10 and 11, which form a kind of edge and serve to integrate the means 8 into the plastic for guiding the flow of the process air, so that, as can be seen more clearly from the enlarged illustration of the Fig. 4, the bulge 9 extends into the interior of the drum 4, thereby causing frequent contact with the material to be dried during the rotation of the drum 4. This improves the overall measurement result and makes it significantly more accurate than with previously known solutions, which also leads to energy savings, because the household appliance 1 switches off when it is determined by an evaluation of the measurement results within the electronic control 5 that the material to be dried contains little or no residual moisture. As can be seen from the Fig. As can also be seen in Figure 4, the surface sections 10 and 11 of the sensor element protrude into the plastic of the means 8 for guiding the process air flow. The sensor element 7 is accommodated entirely in a window 12 of the means 8, which also improves the contact with the material to be dried. LIST OF REFERENCE SYMBOLS: 1 household appliance 2 housings 3 Door 4 drums 5 Electronic control 6 Unit for generating process air 7 Sensor element 8 Means for flow control of the process air 9 Bulging 10 Area section (edge) 11 Area section (edge) 12 windows 13 Control unit 14 compartments 15 Opening 16 air vents 17 trough QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 1 914 341 A1

[0002] EP 3 269 872 A1

[0003] DE 2 839 333 A1

[0004]

Claims

[1] Household appliance (1) with a drying function, comprising a housing (2) in which a rotatably mounted drum (4) closable by a door (3) for receiving the material to be dried and an electronic control (5) are present, further comprising at least one unit (6) for generating process air and means for directing the flow of the process air and at least one measuring unit for determining the moisture content by measuring the conductivity of the material to be dried, wherein the measuring unit in turn comprises at least one sensor element (7) having contact contacts with the material to be dried during the drying process and at least one contact element corresponding thereto, characterized by that the door-side means (8) for guiding the flow of the process air is designed as a plastic injection-molded component which integrates the sensor element (7) during its production by an injection-mold process. [2] Household appliance according to claim 1, characterized by that the door-side means (8) for guiding the flow of process air is a one-piece plastic injection-molded component. [3] Household appliance according to one of the preceding claims, characterized by that the contact element of the measuring unit is arranged on the outside of the metallic drum (4). [4] Household appliance according to claim 3, characterized by that the contact element is arranged adjacent to the axis of rotation of the drum (4). [5] Household appliance according to one of the preceding claims, characterized by that the sensor element (7) has at least one bulge (9) which projects into the interior of the drum (4). [6] Household appliance according to claim 5, characterized by that laterally projecting or circumferentially arranged surface sections (10, 11) extend from the bulge (9) of the sensor element (7) and are integrated into the plastic of the means (8) for guiding the flow of the process air. [7] Household appliance according to one of the preceding claims, characterized by that the sensor element (7) consists of an electrically conductive material and has connecting contacts for indirect, electrically conductive connection with the corresponding contact element. [8] Household appliance according to one of the preceding claims, characterized by that the means (8) for guiding the flow of the process air has a window (12) in which the sensor element (7) is accommodated. [9] Household appliance according to one of the preceding claims, characterized by that the sensor element (7) is 5-15 cm long and 1-3 cm wide. [10] Household appliance according to one of claims 6 to 9, characterized by that the surface sections (10, 11) of the sensor element (7) form an edge which is 0.5 cm all around the sensor element (7).

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