GB1563772A

GB1563772A - Reflux prevention device for dish-washers and the like

Info

Publication number: GB1563772A
Application number: GB9000/78A
Authority: GB
Original assignee: EURO HAUSGERAETE GmbH
Current assignee: EURO HAUSGERAETE GmbH
Priority date: 1977-03-10
Filing date: 1978-03-07
Publication date: 1980-04-02
Also published as: IT7820932A0; FR2382881A1; IT1093172B; SE7802534L; DE2710364C2; DE2710364A1; FR2382881B1

Description

(54) REFLUX PREVENTION DEVICE FOR DISH-WASHERS AND THE LIKE (71) We, EURO HAUSGERATE G.m.b.H., of 6680 Neunkirchen/Wellesweiler (Saar), Heidenhubel, Postfach 1128, Federal Republic of Germany, a German company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: THE INVENTION relates to a reflux prevention device for a water-using machine, in particular a domestic appliance such as a dish-washer, the device having means for connecting a water inlet duct to a machine part, for example a water softener, via a control valve, and the device having an air break in the path of the water supply.

In a water-using machine, such as a dish-washer, the water supply means must be designed so that in the case of a reduction of the pressure within the water supply mains no discharge water can be sucked from the machine back into the water supply main. Generally, this requirement is met by having the water enter the machine via a ventilating free-jet path. In washing machines, but also in dish-washers not having a water softener, this problem is overcome by the provision of a simple air break device. Particularly domestic dish-washing machines generally use softened water, which means that water supply is to be effected via a regenerable water softener unit. As both the passage of water through the softener unit and passage through an associated regenerator, that is a container filled with brine, should be effected under a positive water pressure, non-return valves and vent tubes with inserted movable parts have been used hitherto as reflux-prevention devices. These reflux prevention devices now no longer meet the current requirements of the water supply authorities.

In order to solve this problem free-jet nozzles have been used. These are ventilated housings having two confronting openings (a jet nozzle and a collector funnel) spaced from each other by a free air gap. It has been found that these free-jet nozzles can produce the necessary operating pressure, but that they are extremely susceptible to the presence of any water scale deposit because even a small amount of scale deposit on the nozzle can cause a divergence of the resulting free water jet.

With a substantial divergence, the amount of leakage water which is lost from the collector funnel becomes significant and since this lost water does not get softened it leads to the deposit of an undesirable amount of water hardness scale in the dish-washing machine.

It is an object of the invention to provide a reflux prevention device which is of simple construction, provides good return-flow protection and which ensures that the amount of leakage water remains low.

According to the invention, there is provided a reflux prevention device for a water-using machine, in particular a domestic appliance such as a dish-washer, the device having means for connecting water inlet duct to a machine part, for example a water softener unit, via a control valve, in which rhe water is directed through two water supply sections in a housing which is preferably ventilated to a water container of the machine, said two water supply sections taking the form of curved ducts with a free air gap located at the inside of each curved duct, the sections being offset in such way as to be ventilated to a ventilation opening in the housing.

A reflux prevention device of this type can ensure a correct water supply both via the water softener unit and its re generator.

As in the case of a free air gap the amount of leakage water is always minimal, it is advantageous if the ventilation opening in the housing takes the form of an outlet opening which has an outlet directed towards the water container. In view of the need to locate the reflux prevention device relative to the other parts of the water-using machine, it is advantageous to give the housing a flat shape.

By way of example, -an embodiment of the invention will be described in more detail with reference to the accompanying drawing. In the drawing: Figure 1 schematically represents some parts which are necessary for the water supply of a dish washer, Figures 2 and 3 in plan view and side view schematically show a reflux prevention device, details such as hose connections, thicknesses of the walls which take up the pressure etc., being omitted.

As depicted in Figure 1 in order to fill a washing tub 1 or an associated sump, not shown, of a dish-washing machine respectively, electromagnetic valves 3 and 4 have been incorporated after a water supply line 2. From the valves 3 and 4 hose lines 5 and 6 pass to a reflux prevention device 7 and from there further hose lines 8 and 9 pass to a water softener vessel 10 and a salt dispenser 11. A rising line 12 connects the softener to an outlet ventilator 13 which precedes the tub 1 and which joins the tub 1 at an outlet 14. A free air gap 15 is provided in the reflux prevention device for the line 5, 8 and a similar gap 16 is provided for line 6, 9.

From Figures 2 and 3 it can be seen that the reflux prevention device takes the form of a flat housing, in which channelshaped water supply sections 25 and 26 as well as 28 and 29 are carried. The housing may consist of an injection moulded part the channels being covered by corresponding covering plates. The free air gaps 15 and 16 are connected to an outlet 17 via an open space, through which outlet any leakage water can be discharged into the tub 1. The free air gaps 15 and 16, in accordance with two mutually offset jet nozzles 18 and 19, are freely connected to the outlet 17. The channel-shaped water supply sections 25, 28 and 26, 29 are arcuated in the housing, so that for example a waer jet which is supplied by the line 5 via the nozzle 18 against the outer wall of the channel bridges the air gap 15 without any significant leakage losses and can be fed into the line 8 after being caught by a collector funnel 20. It has been found that a water jet which is thus supplied produces a pressure in the line 8 which is amply sufficient to feed the water through the water softener vessel 10 and the line 12 into the tub 1.

From Figure 3 it can be seen that the water supply sections in the reflux prevention device 7 may have different crosssectional areas because for example the amount of water required for regeneration per unit of time is substantially smaller than that required for filling the machine.

Accordingly, the nozzle 19 has been given a smaller cross-sectional area than the nozzle 18. In the present example the nozzles are slot-like with a rectangular cross-sectional shape, but they may take any other suitable form.

Suitably, the collector funnels 20 and 21 are given a slightly larger cross-sectional area than the corresponding confronting nozzles 18 and 19.

If -- as is shown in the drawing - the free air gaps 15 and 16 are situated at the vertically highest point of the complete water supply system of the machine, it is ensured that at the location of the free air gaps there will be no places likely to retain water so that the formation of scale deposit is unlikely to occur.

Clearly, the housing of the reflux prevention device 7 in addition to its outlet may have further ventilation openings, for example openings disposed at the side of the cover, so that a ventilation which is independent of the tub is possible.

Where the water supply sections are of a parabolic shape, the air gaps may be substantially disposed at the location of the vertex of the parabola.

It has been found that with the described embodiment in which the water supply takes an arcuate or parabolic path, the so-called leakage losses do not exceed 10% even at a low flow rate, that is at a correspondingly low pressure, and at a counter-pressure up to 1.5 bar. For supply conditions, that is at more than five litres per minute, the leakage losses decrease to less than 2%.

WHAT WE CLAIM IS:- 1. A reflux prevention device for a water-using machine, the device having means for connecting a water inlet duct to a machine part, for example a water softener unit, via a control valve, in which the water is directed through two water supply sections in a housing which is preferably ventilated to a water container of the machine, said two water supply sections taking the form of curved ducts with a free air gap located at the inside of each curved duct, the sections being offset in such a way as to be ventilated to a ventilation opening in the housing.

2. A reflux prevention device as claimed in Claim 1, in which the ventilation opening in the housing takes the form

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. generator. As in the case of a free air gap the amount of leakage water is always minimal, it is advantageous if the ventilation opening in the housing takes the form of an outlet opening which has an outlet directed towards the water container. In view of the need to locate the reflux prevention device relative to the other parts of the water-using machine, it is advantageous to give the housing a flat shape. By way of example, -an embodiment of the invention will be described in more detail with reference to the accompanying drawing. In the drawing: Figure 1 schematically represents some parts which are necessary for the water supply of a dish washer, Figures 2 and 3 in plan view and side view schematically show a reflux prevention device, details such as hose connections, thicknesses of the walls which take up the pressure etc., being omitted. As depicted in Figure 1 in order to fill a washing tub 1 or an associated sump, not shown, of a dish-washing machine respectively, electromagnetic valves 3 and 4 have been incorporated after a water supply line 2. From the valves 3 and 4 hose lines 5 and 6 pass to a reflux prevention device 7 and from there further hose lines 8 and 9 pass to a water softener vessel 10 and a salt dispenser 11. A rising line 12 connects the softener to an outlet ventilator 13 which precedes the tub 1 and which joins the tub 1 at an outlet 14. A free air gap 15 is provided in the reflux prevention device for the line 5, 8 and a similar gap 16 is provided for line 6, 9. From Figures 2 and 3 it can be seen that the reflux prevention device takes the form of a flat housing, in which channelshaped water supply sections 25 and 26 as well as 28 and 29 are carried. The housing may consist of an injection moulded part the channels being covered by corresponding covering plates. The free air gaps 15 and 16 are connected to an outlet 17 via an open space, through which outlet any leakage water can be discharged into the tub 1. The free air gaps 15 and 16, in accordance with two mutually offset jet nozzles 18 and 19, are freely connected to the outlet 17. The channel-shaped water supply sections 25, 28 and 26, 29 are arcuated in the housing, so that for example a waer jet which is supplied by the line 5 via the nozzle 18 against the outer wall of the channel bridges the air gap 15 without any significant leakage losses and can be fed into the line 8 after being caught by a collector funnel 20. It has been found that a water jet which is thus supplied produces a pressure in the line 8 which is amply sufficient to feed the water through the water softener vessel 10 and the line 12 into the tub 1. From Figure 3 it can be seen that the water supply sections in the reflux prevention device 7 may have different crosssectional areas because for example the amount of water required for regeneration per unit of time is substantially smaller than that required for filling the machine. Accordingly, the nozzle 19 has been given a smaller cross-sectional area than the nozzle 18. In the present example the nozzles are slot-like with a rectangular cross-sectional shape, but they may take any other suitable form. Suitably, the collector funnels 20 and 21 are given a slightly larger cross-sectional area than the corresponding confronting nozzles 18 and 19. If -- as is shown in the drawing - the free air gaps 15 and 16 are situated at the vertically highest point of the complete water supply system of the machine, it is ensured that at the location of the free air gaps there will be no places likely to retain water so that the formation of scale deposit is unlikely to occur. Clearly, the housing of the reflux prevention device 7 in addition to its outlet may have further ventilation openings, for example openings disposed at the side of the cover, so that a ventilation which is independent of the tub is possible. Where the water supply sections are of a parabolic shape, the air gaps may be substantially disposed at the location of the vertex of the parabola. It has been found that with the described embodiment in which the water supply takes an arcuate or parabolic path, the so-called leakage losses do not exceed 10% even at a low flow rate, that is at a correspondingly low pressure, and at a counter-pressure up to 1.5 bar. For supply conditions, that is at more than five litres per minute, the leakage losses decrease to less than 2%. WHAT WE CLAIM IS:-

1. A reflux prevention device for a water-using machine, the device having means for connecting a water inlet duct to a machine part, for example a water softener unit, via a control valve, in which the water is directed through two water supply sections in a housing which is preferably ventilated to a water container of the machine, said two water supply sections taking the form of curved ducts with a free air gap located at the inside of each curved duct, the sections being offset in such a way as to be ventilated to a ventilation opening in the housing.

of a discharge opening.

3. A reflux prevention device as claimed in Claim 2, in which the discharge opening communicates with the water container.

4. A reflux prevention device as claimed in any one of Claims 1 to 3, in which the housing has a flat shape.

5. A reflux prevention device as claimed in any one of Claims 1 to 4, in which the water supply sections are channel-shaped and closed by covering parts.

6. A reflux prevention device as claimed in Claim 5, in which the water supply sections are carried in the housing.

7. A reflux prevention device as claimed in any one of Claims 1 to 6, in which the water supply sections in the housings are parabolically shaped and that the air gaps are substantially disposed at the location of the vertex of the parabola.

8. A reflux prevention device as claimed in any one of Claims 1 to 7, in which the water supply sections have different cross-sections.

9. A reflux prevention device as claimed in any one of Claims 1 to 8, in which the water supply sections take the form of slot-like nozzles at the location of the free air gaps.

10. A reflux prevention device as claimed in Claim 9, in which the collector funnels have a larger cross-sectional area than the nozzles confronting them.

11. A reflux prevention device as claimed in any one of Claims 1 to 10, in which the water supply sections in the housing and the connections are designed and situated so that the free air gaps in respect of level are located at the vertically highest point of the complete water supply systern of the machine.

12. A reflux prevention device substan tally as hereinbefore described with reference to the accompanying drawing.