Device for dispensing at least one washing agent in a dishwashing machine

Abstract

The dispensing device includes a support body adapted to be mounted on the side of that door of the machine which is facing the washing chamber, in a position such that in the operation this body is periodically flushed, at least in part, by a flow of washing liquid emitted by at least one spraying rotor. In the support body there is incorporated an electrically conducting member whose electric capacitance with respect to earth is variable by the effect of the flow of washing liquid which periodically impinges onto the body; a detection and processing device being connected to the conducting member and being predisposed for detecting the variations of the electric capacitance of said conducting member with respect to earth and for correlating in a predetermined manner said variations with the operation of the spraying rotor.

Description

The present invention relates to a device for dispensing at least one washing agent in a dishwashing machine having a washing chamber which is closed by a door and in which there is mounted at least one spraying rotor for spraying a washing liquid.

More specifically the invention relates to a dispensing device comprising a support body adapted to be mounted on that side of the door which is towards the washing chamber, in a position such that in the operation said body is periodically flushed, at least in part, by a flow of washing liquid emitted by said at least one rotor.

One object of the present invention is to provide a dispensing device of the type specified above, which by simple and inexpensive means allows the modalities of operation of the abovementioned at least one spraying rotor to be detected.

This and other objects are achieved in accordance with the invention by means of a dispensing device of the type specified above, characterized in that in the support body there is incorporated an electrically conducting member whose electric capacitance with respect to earth is variable by the effect of the flow of washing liquid which periodically impinges onto said body; detection circuit means being connected to said conducting member and being predisposed for detecting the variations of the electric capacitance of the conducting member with respect to earth and for correlating in a predetermined manner said variations with the operation of said at least one spraying rotor.

In accordance with another feature, in the support body of the dispensing device there is defined at least one receptacle intended to receive an amount of a washing agent, and to which there is attached a further electrically conducting member which is likewise incorporated in the support body and whose electrical capacitance with respect to earth is variable as a function of the quantity or level of the washing agent in said receptacle, and in which detection circuit means are coupled to said further conducting member and are predisposed to detect variations of the electrical capacitance thereof with respect to earth.

Other features and advantages of the invention will become apparent in the course of the following detailed description, which is given purely by way of non-restrictive example, with reference to the appended drawings, in which:

FIG. 1 is a near-front perspective view of a dispensing device according to the present invention;

FIG. 2 is a diagrammatic side view of the dispensing device shown in FIG. 1; and

FIG. 3 is a block-type circuit diagram of an embodiment of the electrical/electronic part of a dispensing device in accordance with the present invention.

In FIGS. 1 and 2 the number 1 is a general reference for a device according to the invention for dispensing a washing agent in a dishwashing machine.

Referring particularly to FIG. 2, the dishwashing machine M comprises a washing chamber 2 which is closed on one side by a door 3. Mounted inside the washing chamber 2 is at least one spraying rotor of a type also known per se. In the illustrative embodiment shown schematically in FIG. 2 there are three spraying rotors SP1, SP2 and SP3 which are respectively the upper, intermediate and lower rotors.

B1, B2 and B3 are the respective jets of washing liquid emitted by these rotors.

The dispensing device or dispenser 1 is mounted on that side of the door 3 which is towards the washing chamber 2, in a position such that, in the operation said body is periodically flushed, at least in part, by the flows of washing liquid B1, B2 and B3 emitted by said rotors.

Although the embodiment illustrated by way of example in FIG. 2 has three rotors, the invention is not in any way limited to this number, but is applicable also in particular to the case in which the washing chamber of the dishwashing machine has only one or two spraying rotors.

The dispensing device 1 comprises a supporting body 4 in the form of for example a plastic moulding.

With reference to FIG. 1, the supporting body 4 contains two separate receptacles 5 and 6 shown in long and short dashes.

The receptacle 5 is in the shape of a tub, for example, and is designed to hold an amount or dose of a washing agent such as a detergent, e.g. in liquid or powder form. This receptacle is normally closed by a movable lid 7 which can be made to open in a manner known per se by means of an associated electrically driven actuator controlled by a control unit which controls the operation of the dishwashing machine.

The receptacle 6 is designed to contain an amount of another washing agent, such as rinse aid. This amount is usually equal to a plurality of doses, deliverable in succession, in the course of successive wash cycles.

Although the receptacles 5 and 6 in FIG. 1 are shown, for purely illustrative reasons, as essentially parallelepiped-shaped, this shape is in no way binding as these receptacles can be a great variety of different shapes.

Referring to FIGS. 1 and 2, the supporting body 4 of the dispensing device incorporates an electrically conducting member or electrode 10, e.g. in the form of an elongate metal strip, or possibly a conducting wire.

The electrical capacitance of the conducting member 10 with respect to earth is subject to variation during operation due to the flow of washing liquid periodically directed at the dispensing device 1 by the or each spraying rotor.

In the illustrated example of an embodiment, other conducting members 11 and 12 are attached to the receptacles 5 and 6, respectively, for the washing agents (see FIG. 1 in particular).

The electrical capacitances with respect to earth of these further conducting members 11 and 12 will vary in response to the amount or level of washing agents contained in the associated receptacles 5 and 6.

The conducting members 10, 11 and 12 may conveniently be incorporated in the supporting body 4 of the dispensing device during its moulding.

These conducting members are connected to detection and processing circuit devices which will be described later with reference to the conducting member 10, it being understood that the conducting members 11 and 12 are connected to the same or similar detection and analysis circuit devices.

With reference to FIG. 2, the dispensing device 1 comprises a detection and processing circuit device denoted as a whole by the number 20, comprising for example a microprocessor 21. This detection and processing circuit device may conveniently be mounted directly on the body of the dispensing device 1, and may be interfaced with the unit ECU which controls the operation of the dishwasher by means of a connection 22. The latter may simply be a single-wire serial link.

The detection and processing circuit device 20 is connected to earth E, or to the neutral conductor of the AC power supply line, for example by connecting it (directly or via unintended impedances) to the earth conductor or conductors of the dishwashing machine.

This device 20 is connected to the conducting members 10, 11 and 12 and is designed to detect variations in their respective electrical capacitances with respect to earth E.

The detection and processing device 20 is designed in particular to correlate the variations of capacitance with respect to earth of the conducting member 10 with the operation of the spraying rotor or rotors.

On the other hand, the same device 20 is designed to detect variations in the capacitance of the conducting members 11 and 12 with respect to earth E, and to correlate them in predetermined ways with the quantities or levels of washing agents contained in the associated receptacles 5 and 6.

With reference to the block diagram, FIG. 3, in the embodiment which this illustrates schematically and by way of example, the detection and processing device 20 comprises an excitation stage 30 suitable for applying high-frequency electrical excitation signals A, B and C to the conducting members or electrodes 10, 11 and 12, respectively, and an acquisition stage 31 for acquiring, for each of said conducting members or electrodes, corresponding respective low-frequency response signals a, b, c, which are influenced by the respective electrical capacitances with respect to earth of said conducting members or electrodes.

The response signals acquired by the stage 31 are passed to a filter FIR 32, whose output is connected to the input of an up-down counter 33.

The output of the counter 33 is connected to a unit 34 which runs an analytical algorithm. This receives a feedback signal from the acquisition stage 31 via a feedback unit 35. The unit 34 also receives, from a unit 36, the predefined parameter values which define characteristics of the spraying rotor or rotors of the dishwashing machine, and characteristics of the receptacles containing the aforementioned washing agents.

Lastly, the unit 34 is connected to an output unit 37 which produces signals indicating the modes of operation of the spraying rotor or rotors, and signals indicating the amounts or levels of washing agents in the respective receptacles. These signals are sent via the link 22 to the control unit ECU of the dishwashing machine.

Analysis of the response signals obtained from the conducting member or electrode 10 allows the device to discriminate between the following conditions: correct rotation of the spraying rotor or rotors, slow rotation (not correct) of one or more rotors, and one or more rotors not working.

The response signals obtained by the conducting members or electrodes 11 and 12 allow continuous monitoring of the amount or level of washing agents in the associated receptacles.

Clearly, without departing from the principle of the invention, the embodiments and details of construction may vary considerably from those described and illustrated purely by way of non-restrictive example, without thereby departing from the scope of the invention as defined in the following claims.

Claims

1. A device for dispensing at least one washing agent in a dishwashing machine having a washing chamber which is closed by a door and in which there is mounted at least one spraying rotor for spraying a washing liquid; the dispensing device comprising a support body adapted to be mounted on the side of the door facing the washing chamber, in a position such that in the operation said body is periodically flushed, at least in part, by a flow of washing liquid emitted by said spraying rotor;

wherein in said support body there is incorporated an electrically conducting member whose electric capacitance with respect to earth is variable by the effect of the flow of washing liquid which periodically impinges onto said body; detection and processing circuit means, coupled to earth, being connected to said conducting member and being predisposed for detecting the variations of the electric capacitance of said conducting member with respect to earth and for correlating in a predetermined manner said variations with the operation of said spraying rotor.

2. A dispensing device according to claim 1, wherein in said support body there is defined at least one receptacle intended to receive an amount of a washing agent, and to which there is attached a further electrically conducting member which is likewise incorporated in the support body and whose electrical capacitance with respect to earth is variable as a function of the quantity or level of the washing agent in said receptacle, and in which detection and processing circuit means are coupled to said further conducting member and are predisposed to detect variations of the electrical capacitance thereof with respect to earth.

3. A dispensing device according to claim 1, wherein the detection circuit means are predisposed to apply to the or each conducting member a respective high-frequency electric excitation signal and to acquire from the or each conducting member a corresponding low-frequency electrical response signal influenced by the respective electrical capacitance with respect to earth, and to analyse in predetermined ways said or each response signal.

4. A dispensing device according to claim 1, wherein said at least one spraying rotor is rotatable about an essentially vertical axis, and said conducting member has an elongate shape and extends in such a way that in the operation it is at least approximately horizontal.

5. A dispensing device according to claim 2, wherein said at least one further conducting member has an elongate shape, and extends in such a way that in the operation it is at least approximately vertical.