Water-bearing domestic appliance

Abstract

A water-conducting household appliance includes a moving component, an electric motor for moving the component, a load apparatus configured to apply a resistance to counter movement of the component as a function of a position of the moving component, and a control apparatus for actuating the electric motor. The control apparatus is configured to detect a drive current drawn which is drawn by the electric motor and is a function of the resistance applied by the load apparatus and to ascertain the position of the moving component as a function of the detected drive current.

Claims

1. A water-conducting household appliance, comprising: a moving component comprising a spray arm of a dishwasher, the spray arm being configured to perform a rotating movement about an axis; an electric motor for rotatably moving the spray arm; a load apparatus configured to apply a resistance to counter the rotating movement of the spray arm as a function of a position of the spray arm, the load apparatus being configured to apply the resistance a plurality of times as a function of a degree of rotation of the spray arm over one complete movement amplitude of 360 degrees; and a control apparatus for actuating the electric motor, said control apparatus being configured to detect a drive current which is drawn by the electric motor and is a function of the resistance applied by the load apparatus and to ascertain the position of the spray arm as a function of the detected drive current.

2. The water-conducting household appliance of claim 1, wherein the load apparatus comprises a transmission unit for coupling the electric motor to the moving component.

3. The water-conducting household appliance of claim 2, wherein the transmission unit is configured to reduce a rotation speed of the electric motor by a predefined factor when coupling the electric motor to the moving component.

4. The water-conducting household appliance of claim 1, wherein the load apparatus is configured to apply the resistance according to a predetermined load function as a function of a degree of rotation of the moving component.

5. The water-conducting household appliance of claim 1, wherein the load apparatus is configured to apply the resistance as an increased resistance or as a reduced resistance relative to a basic resistance, which corresponds to a resistance when the moving component moves without activation of the load apparatus.

6. The water-conducting household appliance of claim 1, wherein the control apparatus is configured to actuate the electric motor as a function of the ascertained position of the moving component in such a manner that the moving component is moved into a predetermined position.

7. The water-conducting household appliance of claim 1, wherein the control apparatus actuates the electric motor to perform the one complete movement amplitude to ascertain a current load function of the moving component and detects the drive current that has been drawn by the electric motor.

8. The water-conducting household appliance of claim 1, wherein the control apparatus is configured to identify blocking of the moving component as a function of the drive current drawn by the electric motor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further advantageous configurations and aspects of the invention are set out in the subclaims and the exemplary embodiments of the invention described in the following. The invention is also described in more detail based on preferred embodiments with reference to the accompanying figures.

(2) FIG. 1 shows a schematic perspective view of an embodiment of a water-conducting household appliance;

(3) FIGS. 2a and 2b each show a diagram of a drive current drawn by an electric motor;

(4) FIGS. 3a-3c show an embodiment of a load apparatus in one position respectively;

(5) FIGS. 4a and 4b show a further embodiment of a load apparatus in one position respectively; and

(6) FIG. 5 shows a schematic block diagram of an embodiment of a method for operating a water-conducting household appliance.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS OF THE PRESENT INVENTION

(7) Identical elements or those of identical function are shown with the same reference characters in the figures, unless otherwise specified.

(8) FIG. 1 shows a schematic perspective view of an embodiment of a water-conducting household appliance 1, configured here as a household dishwasher. The household dishwasher 1 comprises a dishwashing container 2, which can be closed by a door 3, in particular in a watertight manner. To this end a sealing facility (not shown) can be provided between the door 3 and the dishwashing container 2. The dishwashing container 2 is preferably box-shaped. The dishwashing container 2 can be arranged in a housing of the household dishwasher 1. The dishwashing container 2 and door 3 can form a wash chamber 4 for washing items to be washed.

(9) The door 3 is shown in its opened position in FIG. 1. The door 3 can be closed or opened by pivoting about a pivot axis 5 provided at a lower end of the door 3. The door 3 can be used to close or open a loading opening 6 of the dishwashing container 2. The dishwashing container 2 has a base 7, a top 8 arranged opposite the base 7, a rear wall 9 arranged opposite the closed door 3 and two opposing side walls 10, 11. The base 7, the top 8, the rear wall 9 and the side walls 10, 11 can be made of stainless steel sheet for example. Alternatively the base 7 can be made of a plastic material.

(10) The household dishwasher 1 also has at least one receptacle 12, 13, 14 for items to be washed. A number of, for example three, receptacles 12, 13, 14 for items to be washed can preferably be provided, it being possible for the receptacle 12 for items to be washed to be a lower receptacle for items to be washed or a lower rack, the receptacle 13 for items to be washed to be an upper receptacle for items to be washed or an upper rack and the receptacle 14 for items to be washed to be a flatware drawer. As also shown in FIG. 1 the receptacles 12, 13, 14 for items to be washed are arranged one above the other in the dishwashing container 2. Each receptacle 12 to 14 for items to be washed can be moved as required into the dishwashing container 2 or out of it. In particular each receptacle 12, 13, 14 for items to be washed can be pushed into the dishwashing container 2 in an insertion direction E and can be pulled out of the dishwashing container 2 in a pull-out direction A counter to the insertion direction E.

(11) An electric motor 20, a load apparatus 30 and a moving component 40 are also arranged on the base 7 of the household dishwasher 1. The electric motor 20 is designed to move the moving component 40, which is configured as a spray arm of the household dishwasher 1 here, in particular at a predefined speed. To this end the electric motor 20 is in particular coupled mechanically to the spray arm 40. The spray arm 40 is supported rotatably on an axis (not shown). Movement of the spray arm 40 therefore corresponds to rotation or rotational movement and the predefined speed to a predefined angular speed. The load apparatus 30 is coupled to the rotational movement of the spray arm 40 and is designed to counter the rotation with a resistance, which is a function of the position of the spray arm 40. The position of the spray arm 40 is in particular unambiguously defined by a degree of rotation between 0 and 360°. The resistance countering the rotation means that the spray arm 40 is slowed, reducing the angular speed or rotational frequency of the spray arm 40. A temporarily higher drive power is required to maintain the predefined angular speed. To achieve this, the electric motor 20 temporarily draws an increased drive current I.sub.0, I.sub.1, I.sub.2 (see FIGS. 2a, 2b). The duration of the time interval during which the drive current is increased here is a function in particular of the predefined angular speed and also the angle range in which the resistance is increased.

(12) A control apparatus 50 is also arranged on the door 3 of the household dishwasher 1. The control device 50 is designed to actuate the electric motor 20 to move the spray arm 40. In particular the control apparatus 50 supplies the electric motor 20 with a predefined drive voltage for this purpose and makes the drive current I.sub.0, I.sub.1, I.sub.2 drawn by the electric motor 20 available. The control apparatus 50 is also designed to detect the drive current I.sub.0, I.sub.1, I.sub.2 drawn by the electric motor 20. Based on the detected drive current I.sub.0, I.sub.1, I.sub.2 the control apparatus 50 is also designed to ascertain the position of the spray arm 40. To this end provision can be made for the control apparatus 50 to compare values, perform calculations, determine functional values, perform pattern recognition, in particular a spectral analysis, and/or make assignments.

(13) FIG. 2a shows a diagram of a drive current I.sub.0, I.sub.1 drawn by an electric motor 20 as a function of a degree of rotation φ of a moving component 40. It is for example the electric motor 20 of the household dishwasher 1 illustrated in FIG. 1, which is designed to move the spray arm 40.

(14) A certain basic power is required to move the spray arm 40 and this is for example a function of the manner in which the spray arm 40 is supported. The electric motor 20 achieves this basic power in the present example by drawing a drive current of amplitude I.sub.0. A load apparatus 30 is also provided, which counters movement with an increased resistance in a range of the degree of rotation φ of the spray arm 40 from 135° to 180°. In this range a greater power is required to perform the rotational movement, in particular with a predefined angular speed. Therefore in this range the electric motor 20 draws a greater drive current I.sub.1 to provide this increased power. The control apparatus 50 is designed to detect the drawn drive current I.sub.0, I.sub.1, for example as a function of the degree of rotation φ of the spray arm 40 and to ascertain the position of the spray arm 40 as a function of this.

(15) To this end for example the control apparatus 50 compares the detected drive current I.sub.0, I.sub.1 with a value stored in a storage unit (not shown), which corresponds to the drive current for basic power. If the detected drive current I.sub.0, I.sub.1 is greater than the stored value, the position of the spray arm 40 is in a degree of rotation range from 135°-180°. Alternatively or additionally the control apparatus 50 is designed for example to determine a change in the detected drive current I.sub.0, I.sub.1 and to ascertain the position of the spray arm 40 from this. As soon as the spray arm 40 passes beyond 135°, the drive current I.sub.0, I.sub.1 suddenly increases, resulting in a significant positive change signal. A significant negative change signal results correspondingly when the spray arm 40 passes beyond 180°. In this example therefore the position of the spray arm 40 can be ascertained precisely at two points.

(16) FIG. 2b shows a further diagram of a drive current I.sub.0, I.sub.1, I.sub.2 drawn by an electric motor 20 as a function of a degree of rotation φ of a moving component 40. It is for example the electric motor 20 of the household dishwasher 1 illustrated in FIG. 1, which is designed to move the spray arm 40. A load apparatus 30 (see for example FIG. 1) is also provided, providing a resistance to the rotational movement of the spray arm 40 as a function of position.

(17) In contrast to the example in FIG. 2a, three load levels are shown in FIG. 2b, being characterized by a respective drive current I.sub.0, I.sub.1, I.sub.2. The basic load corresponds to a drive current I.sub.0, an increased load corresponds to a drive current I.sub.1 and a reduced load corresponds to a drive current I.sub.2. In this example three ranges with increased load are provided in the first 90°, at 30° intervals respectively, each spanning 5°-10°. After a further 90° three ranges follow, also at 30° intervals, in which the load is reduced for 5°-10° respectively. The drive current I.sub.0, I.sub.1, I.sub.2 drawn by the electric motor 20 is therefore increased or reduced in the respective ranges.

(18) In this example the control apparatus 50 is therefore able to ascertain the position of the spray arm 40 very precisely.

(19) FIGS. 3a-3c show an embodiment of the load apparatus 30, for example the load apparatus 30 from FIG. 1, in one position respectively. In this example the load apparatus 30 comprises two toothed wheels 31, 32, which engage in one another. The first toothed wheel 31 is mounted on a shaft or drive axle 21, which is driven by the electric motor 20 (see FIG. 1), possibly by way of a transmission unit (not shown). The teeth of the first toothed wheel 31 engage in the teeth of the second toothed wheel 32, transferring a force to the second toothed wheel 32. The second toothed wheel 32 is mounted in particular on a shaft or drive axle 41, which is designed to drive or move a moving component 40 (see FIG. 1). The first toothed wheel 31 has the particular feature that there are no teeth present in a small angular range. When this angular range of the first toothed wheel 31 faces the second toothed wheel 32, no force is transferred to the second toothed wheel 32. This means that a load, which is coupled to the second toothed wheel 32, such as the moving component 40, is not driven in this range. No drive power is therefore required and a drive current I.sub.0, I.sub.1, I.sub.2 (see FIGS. 2a, 2b) drawn by the electric motor 20 driving the first toothed wheel 31 is therefore reduced relative to a basic load.

(20) FIG. 3a shows a moment when the second toothed wheel 32 is still being driven by the first toothed wheel 31. The first toothed wheel 31 nevertheless continues to rotate in the rotation direction shown, with the result that the angular range of the first toothed wheel 31, in which there are no teeth present, is rotated toward the second toothed wheel 32.

(21) FIG. 3b shows a moment when the angular range of the first toothed wheel 31, in which there are no teeth present, is facing the second toothed wheel 32. In this position therefore the second toothed wheel 32 is also not driven and a load for the electric motor 20 and therefore also a drive current I.sub.0, I.sub.1, I.sub.2 drawn by it are reduced. The moving component 40 possibly also continues to move at this moment due to movement inertia. However the movement is preferably slowed so the moving component 40 is in a defined position.

(22) FIG. 3c shows a moment when the first toothed wheel engages in the second toothed wheel 32 again and therefore drives it again. The load and therefore also the drawn drive current I.sub.0, I.sub.1, I.sub.2 are back to the basic level again after this time point. It can therefore happen that at the first moment, when the first toothed wheel 31 engages in the second toothed wheel 32 again, an increased load temporarily results, when the moving component 40 has been slowed for the time being and then speeded up again.

(23) FIGS. 4a and 4b show a further embodiment of a load apparatus 30, for example the load apparatus 30 from FIG. 1, in one position respectively. In this example the load apparatus 30 has a concentric structure with cylindrical elements 33, 34, 35 arranged inside one another. A friction means 33 is arranged on an inner shaft or drive axle 21, being connected in a fixed manner to the drive axle 21. The friction means 33 comprises polymer components in particular. At a distance from the friction means 33, which forms a gap, is a friction layer 34, which for its part is arranged on the inner face of a sleeve 35 and connected in a fixed manner thereto. The sleeve 35 is connected in a fixed manner for example to an external housing (not shown) and therefore unmovable.

(24) The friction means 33 has a particular feature in the form of a projection 36, which is so large that it bridges the gap between the friction means and the friction layer 34. In other words the projection 36 touches the friction layer 34 and rubs against it. This is shown by way of example in FIG. 4a. Such friction causes an increased resistance to counteract rotation of the drive axle 21. The projection 36 can be made of the same material as the friction means 33 but provision can also be made for it to be made of a different, in particular more robust, material or for a coating of a more robust material to be applied to it.

(25) The friction layer 34 has a further particular feature in the form of a cutout 37. This cutout 37 is dimensioned such that the projection 36, when aligned in the direction of the cutout 37, no longer rubs against the friction layer 34. This is shown by way of example in FIG. 4b. Therefore the additional load generated by friction is no longer present in this alignment, in other words when the projection 36 is aligned toward the cutout 37.

(26) Therefore an increased basic load, which is reduced specifically in one position, is generated for the load apparatus 30 in this exemplary embodiment.

(27) FIG. 5 shows a schematic block diagram of an embodiment of a method for operating a water-conducting household appliance 1, for example the household dishwasher in FIG. 1.

(28) In a first method step S1 an electric motor 20 is actuated by a control apparatus 50. This means in particular that the control apparatus 50 supplies the electric motor 20 with a predefined drive voltage and makes available a drive current I.sub.0, I.sub.1, I.sub.2 drawn by the electric motor 20 (see FIGS. 2a, 2b).

(29) In a second method step S2 a load apparatus 30 (see FIGS. 1, 3a-3c, 4a, 4b) provides a resistance, which is a function of a position of a moving component 40 driven by the electric motor 20.

(30) In a third method step S3 the drive current I.sub.0, I.sub.1, I.sub.2 which is drawn by the electric motor 20 and is a function of the resistance provided, is detected. For example the control apparatus 50 has a current measuring device for this purpose. Detection of the drive current I.sub.0, I.sub.1, I.sub.2 can also include storing the detected value.

(31) In a fourth method step S4 the position of the moving component 40 is ascertained as a function of the detected drive current I.sub.0, I.sub.1, I.sub.2. It is ascertained in particular by the control apparatus 50, for example by comparing the detected drive current I.sub.0, I.sub.1, I.sub.2 with values stored in a table.

(32) Although the present invention has been described based on exemplary embodiments, it can be modified in many different ways.

(33) In particular there are many conceivable further variants for the load apparatus. For example, as an alternative to the extensive friction layer illustrated in FIGS. 4a, 4b, provision can be made for friction points only to be arranged at individual points in order not to increase the basic load. Different materials or coatings can also be provided for the friction layer, having different friction coefficients and therefore bringing about different load states. In addition to the proposed mechanical load apparatuses magnetic ones are also conceivable, influencing a course of movement of the moving component in a predetermined manner as a function of position using appropriately arranged permanent magnets.