EP1530942A1

EP1530942A1 - Dishwasher provided with improved control device

Info

Publication number: EP1530942A1
Application number: EP03025901A
Authority: EP
Inventors: Claudio Cenedese; Giampaolo Burello; Sergey Argudyaev; Maurizio Ugel
Original assignee: Electrolux Home Products Corp NV
Current assignee: Electrolux Home Products Corp NV
Priority date: 2003-11-12
Filing date: 2003-11-12
Publication date: 2005-05-18

Abstract

Dishwasher controlled by a programming device (16) and comprising a cabinet (10) which encloses a tub (11) and at least a basket (12) mounted inside the tub for supporting dishware.

A sensor of electric field intensity (14) is connected to at least an electrode (15) located inside the tub form one side and with the programming device (16) from the other side, in order to detect some characteristics of the load into the machine.

Technical solution which is particularly cheap, simple and reliable, and may interact with components already present in the machine.

Description

The present invention refers to a dishwasher, particularly of domestic type, which is provided with an improved control device, in order to make the machine more "intelligent" in its use.
Dishwashers are normally provided with interfaces, which allow users to select different working cycles depending on the amount of load of dishware charged into the machine and the relevant dirty degree. However, even an expert user may give a wrong evaluation of the charge so as to select an inappropriate cycle.
It is also known to employ sensors which detect various functional characteristics of the machine, e.g. rotation of the spray arms, water charge and the like, and give corresponding warnings in case of malfunctioning. Such kind of information are simply passive, i.e. they do not modify the behaviour of the machine but ask for an action by the user.
US patent No. 5,330,580 discloses a dishwasher incorporating a closed loop system for controlling machine load that includes a sensor for detecting power consumption surges. However, the system is limited for controlling the amount of liquid to be delivered into the washing tub.
As all modem appliances, also dishwashers are requested to be more and more self-controlling, particularly with the scope to save water and energy or reduce the washing time and environmental pollution. This means to make intelligent machines.
From this point of view, a very helpful feature for a dishwasher should be a control device which is able to detect type and amount of loaded dishware and to decide automatically the right cycle to be activated.
A solution has been proposed which employs a videocamera (DE-A-10048081), but clearly it involves technical problems for assembling, protecting and setting such a delicate component, beside its high cost.
US patent No. 6,622,754 discloses another solution, wherein the dish load for an automatic dishwasher is determined by detecting temperatures of the dishes in different time of the washing cycle and comparing the relevant ratios to a predetermined threshold value in order to evaluate amount dishware loaded into the machine.
The main purpose of the present invention is to provide a dishwasher having an improved control device which should be able to detect some characteristics of the load in order to let the electronic control to select or modify the washing program of the machine.
Another purpose of the invention is to arrange the dishwasher with a new control device which is cheap, simple and reliable, and may interact with components already present into the machine.
Again, a purpose of the invention is to provide a dishwasher with a control device which is multifunctional, so as it can be applied to detect a number of different features of the machine.
According to the present invention these purposes are achieved by a dishwasher provided with a sensor device of electric field as described in the appended claims.
The invention will be better appreciated from the following description given solely by way of non-limiting example and with reference to the accompanying drawings, in which:

Figure 1 shows schematically a first embodiment of a dishwasher according the present invention;
Figure 2 shows schematically a second embodiment of a dishwasher according to the present invention;
Figure 3 shows schematically a third embodiment of a dishwasher according to the present invention;
Figure 4 shows schematically a plan view of the dishwasher of Figure 3.

Figure 1 refers to a first embodiment of a dishwasher according to the invention and represented in a schematic way. The machine comprises essentially a cabinet 10 which encloses a tub 11. At least a basket 12 is mounted inside the tub for supporting dishware. A spray arm 13 is associated to the basket and is rotated to spray washing liquor against the surface of dishware.
A sensor of electric field intensity 14 is connected to at least an electrode 15 located inside the tub from one side, and with the programming device 16 from the other side. This sensor is able to detect changes in the electric field around said electrode, that acts as an antenna. In particular, this arrangement allows to detect the type and amount of items which are charged into the tub of the dishwasher, since different materials have different electric permeability with respect to an electric field. Therefore, it is possible with a proper design of the antenna to detect the configuration of the electrical field inside the tub at empty machine and after the load of dishware in it. By comparing these measures, a signal is issued form the sensor 14 to the programming device 16 for setting the right washing cycle requested by the present dishware load.
A sensor adapted for the scope previously described is an electric field sensor for applications where non-contacting sensing of objects is desired. An example is the IC called MC33794 Electric Field Imaging Device, produced by Motorola Inc. It contains circuitry necessary to generate a low level electric field and measure the field loading caused by objects moved into the field associated with an electrode. The IC generates a low frequency sine wave, which is used to drive up to nine electrodes. A microcontroller unit (MCU) can be programmed to interpret the resulting data and make the determination of an object interfering in the electric field.
Figure 1 shows a first embodiment of the invention, wherein the electrodes 15 are shaped as sheets applied on the internal surface of the tub 11 and are connected by electric wires 17 to the sensor 14.
Figure 2 shows a second embodiment of the invention, wherein the electrodes 15 are shaped as nets placed in the gap between the wall of the tub 11 and the two baskets 12.
Figure 3 shows a third embodiment of the invention, wherein each basket 12 or portion of the basket, like the grid normally present to support a row of dishes, acts as an electrode and is directly connected to the sensor 14. The connection of the slidable basket 12 to the sensor 14 can be achieved by means of a watertight contact 18, as shown in Figure 4. The contact 18 is fastened to the rear wall of the tub 11 and is protected by an elastic bellow 19. The contact is activated when the basket 12 is fully entered inside the tub.
As the sensor 14 is able to drive up to nine electrodes, some of them may be used to control different components of the machine, by using the sensor as a multipurpose user interface. An electrode may be associated, for instance, to the valve controlling the water flow to the upper spray arm. Another electrode may be used to detect possible loss of water on the bottom of the machine or to detect the moisture degree of dishware in order to control the drying process.
In conclusion, the technical feature of the present invention allows to achieve a control system for a dishwasher which is reliable in use, easy to be applied to the machine without substantial change in the structure of the same, and able to control different functions.

Claims

Dishwasher, particularly of domestic type, controlled by a programming device (16) and comprising a cabinet (10) which encloses a tub (11) and at least a basket (12) mounted inside the tub for supporting dishware, characterised in that a sensor of electric field intensity (14) is connected to at least an electrode (15) located inside the tub from one side, and with the programming device (16) from the other side.
Dishwasher according to claim 1, characterised in that the sensor (14) is able to detect changes in the electric field around the electrodes (15) which act as antennas.
Dishwasher according to claim 1, characterised in that the sensor (14) is connected to a plurality of electrodes (15) shaped as sheets applied to the inner surface of the tub (11).
Dishwasher according to claim 1, characterised in that the sensor (14) is connected to a net of electrodes (15) shaped as nets placed in the gap between the wall of the tub (11) and the basket (12).
Dishwasher according to claim 1, characterised in that the sensor (14) is connected to the basket itself (12), or portion of the baskets, which acts as electrode.
Dishwasher according to claim 5, characterised in that the basket (12) is connected to the sensor (14) through a watertight contact (18).