A dishwasher provided with an integrated system for controlling quantities of water

Abstract

 The dishwasher includes:
- a water feed and treatment device (10) comprising a feed pipe (16) with a filling valve (18), a first reservoir (28) for containing substances with decalcifying properties, and a second reservoir (30) for containing salt to be dissolved in water in order to generate a brine for the regeneration of these substances; and
- a control system comprising a sensor (42) located in a well (12) which forms the base of the washing chamber (14), and a control unit (44) for receiving signals sent by the sensor (42) and for measuring, on the basis of these signals, the quantity of water used to regenerate the substances with decalcifying properties.

Description

[0001] The present invention relates to a dishwasher. More specifically, the dishwasher is provided with a water feed and treatment device comprising a feed pipe with a filling valve, a first reservoir for containing substances with decalcifying properties, and a second reservoir for containing salt.

[0002] As is known, after a number of washing cycles depending on the hardness of the water at the location where the dishwasher is installed, the substances with decalcifying properties have to be regenerated by a flow of brine which is produced by making a certain quantity of water flow through the second salt reservoir. In the prior art, this quantity is controlled by various systems, for example by providing a suitable collecting vessel with an appropriate volume, or by measuring the quantity with a flow meter, or by opening a diversion valve for a specified interval of time.

[0003] All of these known systems are intended to perform either the sole function of controlling the quantity of water for generating the brine, or this function combined with the additional function of measuring the quantity of water used to fill the machine. In both cases, they form a supplementary component of the dishwasher, in addition to the safety devices that must be provided in all cases to determine the presence of a minimum quantity of water in the washing chamber, resulting in a complicated and expensive structure.

[0004] The object of the present invention is to overcome this drawback.

[0005] This object is achieved by means of a dishwasher which includes:

• a water feed and treatment device comprising a feed pipe with a filling valve, a first reservoir for containing substances with decalcifying properties, and a second reservoir for containing salt to be dissolved in water in order to generate a brine for the regeneration of said substances, and
• a control system comprising a sensor located in a well which forms the base of the washing chamber and a control unit for receiving signals sent by said sensor and for measuring, on the basis of said signals, the quantity of water used to regenerate the substances with decalcifying properties.

[0006] The essential component of the control system of the dishwasher according to the invention is the sensor, which is typically a pressure sensor which is normally present in known dishwashers, in which it operates solely as part of a safety system for stopping the operation of the machine when there is insufficient water in the washing chamber. According to the present invention, however, this pressure sensor is also used to control the quantities of water required, in particular, for the execution of the regeneration cycles. Consequently, the components required for this function are available at very little cost or at no cost at all.

[0007] The control system of the dishwasher according to the invention also has the advantages of providing a high level of accuracy in measurement and of also making it possible, if desired, to measure a quantity of water required for washing the substances with decalcifying properties after the regeneration treatment.

[0008] Further advantages and features of the present invention will be made clear by the following detailed description, which refers to the attached drawings provided by way of non-limiting example, in which:

Figure 1 is a schematic representation of the principal components of a dishwasher according to the invention, and

Figure 2 is a schematic representation of the components of Figure 1 in a different operating configuration, namely that used for the regeneration stage.

[0009] A dishwasher (Fig. 1) comprises a water feed and treatment device 10 and a well 12 placed at the bottom of the washing chamber 14.

[0010] The water feed and treatment device 10 comprises a feed pipe 16, on which is fitted a filling valve 18 and, downstream of the latter, a "jump in the air" portion 20. A diversion valve 22 is also fitted on the pipe 16, the pipe being divided into a first branch 24 and a second branch 26 at the position of this valve. The first branch 24 opens into a first reservoir 28 for containing substances with decalcifying properties, particularly ion exchange resins, while the second branch 26 opens into a second reservoir 30 for containing salt, the outlet aperture 32 of this reservoir being connected by another pipe 34, provided with a selective shut-off device 36, to the first reservoir 28.

[0011] The first reservoir 28 has an outlet aperture 38 connected by a discharge pipe 40 to the bottom of the well 12, where a pressure sensor 42, for example a sensor of the type described in IT-1 337 356, is located.

[0012] A control unit 44 can receive signals sent by the pressure sensor 42, and can determine the quantity of water present in the well 12, on the basis of these signals; it can then act accordingly to open or close the filling valve 18 and to control the setting of the diversion valve 22.

[0013] In the normal operation of the dishwasher (Fig. 1), the water fed through the pipe 16 passes through the first reservoir 28 (arrow 46) where it is decalcified, then enters the discharge pipe 40 and is guided (arrow 48) into the well 12. On the basis of the signals received from the sensor 42, the control unit 44 operates the filling valve 18, keeping it open for the time required to allow the inflow of the quantity of water necessary for the execution of the desired washing programme. In this stage of operation, the control unit 44 also controls the diversion valve 22 in such a way that it directs the water which is fed in into the first branch 24 of the pipe 16.

[0014] After a number of washing cycles depending on the hardness of the water at the location where the dishwasher is installed, the resins contained in the first reservoir 28 have to be regenerated. For this purpose, the control unit 44 operates the diversion valve 22 in such a way that (Fig. 2) it directs the water which is fed in into the second branch 26 (arrow 50), from where it flows into the second reservoir 30 to form a brine which is directed (arrow 52) through the additional pipe 34 into the first reservoir 28, where it regenerates the spent ion exchange resins. The flow of water from the first reservoir 28 is then directed (arrow 48) into the well 12 through the discharge pipe 40. On the basis of the signals received from the sensor 42 in this stage of operation, the control unit 44 controls the setting of the diversion valve 22 in such a way that it directs the water which has been fed in into the second branch 26 for the time required to allow the necessary quantity of water to flow into the second reservoir 30 in order to generate the desired brine for regeneration.

[0015] It is clear from the above description that the control unit 44 acts on the basis of the signals received from the sensor 42 to operate the filling valve 18 and control the diversion valve 22 in such a way that these valves cause the quantity of water required for a given washing programme to flow into the washing chamber 14 and cause the necessary quantity of water to flow into the salt reservoir 30 to generate the brine to be used for regenerating the ion exchange resins, respectively.

[0016] The control unit 44 performs other functions concerned with safety, on the basis of the signals received from the sensor 42. For example, if the quantity of water in the well 12 is less than a specified amount, the control unit 44 prevents the activation of the washing water heating means, typically an electrical resistor, so that the operation of the dishwasher is stopped or prevented even before its commencement. Similarly, if the quantity of water in the well 12 and in the chamber 14 is greater than a specified amount, the control 44 stops the operation of the dishwasher or prevents it from starting, thus acting as a safety device for preventing overflow.

[0017] Also acting on the basis of the signals received from the sensor 42, the control unit 44 measures the quantity of water that has passed through the first reservoir 28, in order to determine when it is necessary to regenerate the substances with decalcifying properties contained therein, and also checks that the well 12 has been emptied at the end of the washing cycle. The control unit 44 can also record data processed on the basis of these signals, to be used as a reference to determine the quantity of filling water for a subsequent washing cycle.

[0018] Thus the dishwasher is provided with an integrated system for controlling the quantities of water, in which the same components are capable of making a plurality of measurements of pressure, and consequently of level, the results of these measurements being used for different purposes.

[0019] The fact that such a control system also performs safety functions does not mean that a dishwasher provided with the system may not be equipped with other safety devices as well, in order to provide better protection against leaks.

[0020] An example of another safety device which could be used is the device housed on the bottom of the base of a dishwasher as described in patent application EP-1 836 943, the content of which is incorporated by reference in the present description. This safety system comprises: a stationary chamber for collecting leaking water, having an aperture for the entry of the water and a constricted aperture for the outflow of the water into an auxiliary chamber; a member located in the collection chamber and capable of floating on the water collected therein; and a switch placed above the floating member and capable of being operated thereby when the water reaches a predetermined level within the collection chamber and thus causes the floating member to rise.

[0021] Clearly, provided that the principle of the invention is retained, the details of construction and the forms of embodiment can be varied widely from what has been described purely by way of example, without departure from the scope which has been claimed. As an alternative to the system described above, the diversion valve 22 could cause only part of the water to flow into the second branch 26 in the regeneration stage, allowing the remainder to continue flowing into the first branch 24 and to be fed directly into the first reservoir 28. The water feed and treatment device 10 could also comprise another branch acting as a by-pass running around the first reservoir 28 which contains the exchange resins.

Claims

1. A dishwasher, including

- a water feed and treatment device (10) comprising a feed pipe (16) with a filling valve (18), a first reservoir (28) for containing substances with decalcifying properties, and a second reservoir (30) for containing salt to be dissolved in water in order to generate a brine for the regeneration of said substances, and

- a control system comprising a sensor (42) located in a well (12) which forms the base of the washing chamber (14), and a control unit (44) for receiving signals sent by said sensor (42), and for measuring, on the basis of said signals, the quantity of water used to regenerate the substances with decalcifying properties.

2. A dishwasher according to Claim 1, in which said water feed and treatment device (10) also comprises a diversion valve (22) for directing the water into the first reservoir (28) and/or into the second reservoir (30), and said control unit (42) controls the setting of the diversion valve (22) in such a way that the quantity of water required to generate the desired brine for regenerating the substances with decalcifying properties contained in the first reservoir (28) is made to flow into the second reservoir (30) when said regeneration is to be carried out.

3. A dishwasher according to Claim 1 or 2, in which the control unit (44) receives signals sent by said sensor (42) and measures, on the basis of said signals, the quantity of water present in the well (12), so as to cause the filling valve (18) to open or close in order to make the quantity of water required for the execution of a washing programme flow into the washing chamber (14).

4. A dishwasher according to any one of the preceding claims, in which the control unit (44) prevents the activation of the washing water heating means in order to stop the operation of the dishwasher or to prevent it from starting, if the quantity of water present in the well (12) which has been measured by means of the signals sent by the sensor (42) is less than a specified value.

5. A dishwasher according to any one of the preceding claims, in which the control unit (44) stops the operation of the dishwasher or prevents it from starting if the quantity of water present in the well (12) and in the chamber (14) which has been measured by means of the signals sent by the sensor (42) is greater than a specified value, thus acting as a safety device for preventing overflow.

6. A dishwasher according to any one of the preceding claims, in which said control unit (44) measures, on the basis of said signals, the quantity of water that has passed through the first reservoir (28), in order to determine when it is necessary to regenerate the substances with decalcifying properties contained in the first reservoir (28).

7. A dishwasher according to any one of the preceding claims, in which said control unit (44) checks the emptying of the well (12) on the basis of said signals.

8. A dishwasher according to any one of the preceding claims, in which said control unit (44) records data processed on the basis of said signals, these data being used as a reference to determine the quantity of water required for subsequent filling.

Drawing