EP1121893A2

EP1121893A2 - Device for supplying washing liquid in the tub of a household washing machine, in particular a dishwasher

Info

Publication number: EP1121893A2
Application number: EP01101222A
Authority: EP
Inventors: Carlo Carli
Original assignee: T&P SpA
Current assignee: T&P SpA
Priority date: 2000-01-21
Filing date: 2001-01-19
Publication date: 2001-08-08
Also published as: ITTO20000064A1; IT1319801B1; EP1121893A3

Abstract

Device for supplying washing liquid to a household washing machine, in particular a dishwasher, said device (1) having a body (2) consisting of two parts (2A,2B) substantially mirror-like welded to each other, where inside said body (2) one or more functional elements (3,4,6,9,13,14) are delimited, such as a water non return device (3) to the waterworks, and/or at least a chamber (4) for collecting water, in particular required for regenerating the softening resins of the washing water, and/or at least a vent (14) directed to the outer environment, and/or at least an outlet column (13) for the steam coming from the wash tub of the machine, said column (13) being in communication with said tub through an opening (12), and/or at least a duct (6;9) to let water flow through, wherein one or more of said operating elements (3,4,6,9,13,14) are at least partially formed or delimited inside said body (2) by portions of said two parts (2A,2B) welded between them. According to the invention, means (15) are provided for checking or verifying the efficiency condition of all weld areas between said two parts (2A,2B) located inside said body (2).

Description

The present invention refers to a device for supplying washing liquid in the tub of a household washing machine, in particular a dishwasher.
As known, dishwashers comprise a device for supplying washing liquid in the wash tub, which device is located outside the tub itself, usually on one of its side walls.
This device performs several essential functions, such as:

a water non return device to the waterworks by means of an air break, in the event of a likely depression within the water system itself,
collecting water for regenerating the softening resins of the washing water,
a vent directed to the outer environment, as required for preventing any overpressures on the pressure switch, which may cause a wrong operation of the latter or possible malfunctions,
an outlet column for the steam coming from the wash tub and its partial condensation before being discharged in the environment.

These functions are obtained by means of ribs delimiting a number of water flow channels, at least a chamber collecting water for regeneration purposes and vent openings, of which one at least is located in line with an opening of the wash tub for venting the steam that forms inside the tub, and at least another one on the top of the connecting device to the outer environment.
As known, this device consists of two half-shells, which are subsequently welded between them by a hot blade welding process.
The air break, besides performing the function of a water non return device to the waterworks, has to warrant, according to market specifications, a water leak not exceeding the total amount of water supplied to the dishwasher by 3-5%. This maximum value is due to the fact that a water leak from the air break will be conveyed in the wash tub directly through the steam vent opening without flowing through the decalcifying device; this will entail consequent problems, such as calcareous rests on the dishes.
Therefore, to ensure a correct air break execution, a half-moon shaped insert assuring extremely controlled dimensions is utilized. In fact, during the hot blade welding stage of both half-shells, the material of the ribs forming the water flow channels will melt and form a flash that solidifies after the welding process, whose dimensions cannot be controlled. Moreover, this flash would be deleterious in line with an air break flow, because the fluid streams tending to follow the channel shapes by adhesion surface will follow the flash and let a consistent amount of the water supplied flow out.
Introduction of an additional insert in a half-shell, before the hot blade welding process, will not only increase its assembly costs, but cause problems for the automated manufacturing process of the device, as high investment costs are involved. Moreover, should an additional component be erroneously omitted, operating problems would then ensue.
Moreover, inserting any additional element inside the device, will not allow its manufacture as a single body, since insertion of an additional element requires manufacture of the device in two pieces, for its assembly on one of the two parts before welding them together.
A further drawback of the devices manufactured according to the known state of the art is represented by a faulty welding of the two half-shells with a consequent water leakage when the device is assembled in a washing machine. Quite often, such a defective welding of the two half-shells is not detected by present processes, since the device has openings and outlets towards the outer environment, which hinder a weld check letting air in, as normally done for other devices manufactured with a hot blade welding process, which have a sealed volume.
A water leakage outside the device may occur due to a defective peripheral welding, with consequent electric safety issues, since the leak may involve electric components located in the lower section of the washing machine, or water dripping on the floor where the washing machine is resting.
In order to obviate to this drawback, are know devices that have their peripheral edge consisting of two parallel ribs so as to form a closed gap between them along the whole perimeter of the device after welding both half-shells. Correct execution of the welding can be detected by injecting an air jet in this gap through a hole made at the moment, making sure there is no pressure drop of the air introduced therein.
This system allows detecting a peripheral leakage but not an inner leakage, which may not even be detected after the device has been assembled on the washing machine.
An inner leakage, due to a defective welding, may cause several issues according to the location where the leak takes place and its amount. Should a leak occur, for example, between the water collecting chamber for resins regeneration and the water inlet duct to the wash tub, then the amount of water required for a satisfactory resins regeneration would decrease with consequent calcareous deposit inside the machine.
If the leak occurs on the ribs near the air break or near the rib separating the steam vent from the collecting chamber for the regeneration water, then the wash tub will take in a higher amount of non decalcified water and undergo the same effects as described above.
In the particular event of a leakage occurring on a rib upstream the air break and the channel downstream the air break, a backflow of polluted water may occur to the main following a pressure drop in the waterworks, i.e. a serious malfunction of the non return device, which is an obvious infringement of the existing standards.
It is the object of the present invention to solve the above drawbacks of the devices already known.
In this frame, it is a main object of the present invention to provide a device supplying washing liquid in the tub of a household washing machine, in particular a dishwasher, in which the device is of simple and compact realization, and therefore economical, ensuring an improved performance reliability as well as an easier, cost-effective production, with respect to the solutions already known.
A further object of the present invention is to provide a above mentioned device having a higher reliability, by virtue of its means apt for detecting any welding faults.
Another object of the present invention is to provide a device, which can be manufactured as one piece alone.
These and others aims are achieved according to the present invention by a device for supplying washing liquid in the tub of a household washing machine, in particular a dishwasher, incorporating the features of the annexed claims, which form an integral part of the description herein.
Further objects, features and advantages of the present invention will become apparent from the following detailed description and annexed drawings, which are supplied by way of non limiting example, wherein:

Fig. 1 shows schematically a vertical section of a device for supplying washing liquid in the tub of a household washing machine, according to the present invention;
Fig. 2 shows an enlarged scale of a cross section of the channel in the air break area before welding, according to the present invention;
Fig. 3 shows an enlarged scale of a cross section of the channel in the air break area after welding, according to the present invention.

In Fig. 1 is represented a vertical section of a metering device of the washing liquid in the tub of a household washing machine, according to the present invention.
In this figure, reference 1 indicates the device for supplying the washing liquid, which consists of two substantially symmetric half-shells welded together by the hot blade welding process, reference 2 indicates the device body; reference 3 indicates an air break operating as a water non return device to the waterworks, reference 4 indicates a chamber for collecting regeneration water for the softening resins of the washing water, reference 5 indicates a connector of the device 1 for its connection to the waterworks; a solenoid valve controlled by a programming device of the washing machine is located between the connector 5 and the waterworks.
Water reaching the connector 5 is further conveyed inside a duct 6, flows through the air break 3 and enters in the chamber 4 through an opening 7. After filling the chamber 4 and overcoming a partition level 8, water overflows into a second duct 9, and through a second connector 10 reaches the wash tub flowing through a softening device (not shown here).
Reference 11 indicates a third connector for connecting the chamber 4 to a salt stank for regenerating the softening resins of the washing water. Water flow from chamber 4 to the salt tank is controlled by a solenoid valve driven by the programming device of the washing machine.
Reference 12 indicates an opening for collecting the steam coming from the wash tub, reference 13 indicates a vent and condensing chamber of said steam, which is then discharged in the environment through a second opening 14 placed on top of the vent chamber 13. The opening 12 also operates to let any water unable to overcome the air break 3 enter the wash tub.
The surrounding walls of the body 2 and those delimiting the ducts 6 and 9, the chamber 4 for collecting regeneration water, the vent chamber 13 and the air break 3, are obtained with a double rib indicated with 15A and 15B respectively, so as a continuous closed volume channel 15 between both ribs is obtained when welding both half-shells to each other.
The double wall delimiting the ducts 6 and 9, the chamber 4 for collecting regeneration water, the vent chamber 13 and the air break 3 is obtained by the rib 15B alone, which extends continuously inside the body 2. Moreover, the ducts 6 and 9 are obtained by the wall 15B.
The weld of both half-shells require heating of the ribs until their ends reach a plastic state and then joined them under a certain pressure, causing the ribs of both half-shells enter each other, then letting the whole set cool down. This procedure causes an height reduction of the ribs and consequently of the channel 15; in order to avoid that the air contained in the channel 15 may be compressed and cause welding problems, a hole 16 is provided in the outer wall of the channel of one of the two half-shells, which will let the air inside the channel 15 flow outside.
The hole 16, besides letting the air contained in the channel 15 flow out during the welding of both half-shells, is utilized during the testing stage of the device 1 to verify a correct welding execution.
In fact, the test is performed introducing an air jet in the channel 15 through the hole 16, making sure no air pressure drop occurs. In the event of a pressure drop, this means that the weld has a leak, so the component will be rejected and not used.
Thus, all manufactured devices can be checked and their defective rate due to a faulty welding practically reduced to zero.
In order to avoid that welding flash in the air break area may cause any issues as mentioned above, the channel near the air break is manufactured according to the illustrations in Figs. 2 and 3.
In these figures, representing an enlarged scale of the cross section of the air break area before and after welding both half-shells, references 2A and 2B indicate both half-shells, reference 6 indicates in Fig. 2 the duct before welding and in Fig. 3 the duct after welding both half-shells. Reference 18 indicates two equal recesses realized in the rib 15B, which are delimited on one side by a wall 19 of the duct 6 and on the other side by a wall 20 delimiting the outer side of the rib 15B.
When both half- shells 2A and 2B of the device 1 are positioned one on top of the other for welding, the wall 20 of one is in contact with the same wall 20 of the other, whereas a certain clearance exists between the wall 19 of one and the wall 19 of the other (see Fig. 2). The distance between the walls 19 of both half-shells is so selected to be in line with the height reduction of the walls 20 during welding of both half-shells, as described above.
As a result, at the end of the welding process, both walls 19 will match without being welded, thus avoiding possible flash formation in line with a path having an air cut, which may favor the outlet of a consistent portion of the water flowing through the air break.
Welding of the walls 20 will produce a flash indicated with 21, which is due to the squeezing of the two shells during welding and to the plasticity of the walls 20 for their welding.
However, the flash 21 does not involve the duct 6, since a portion of it is contained in the recess 18, delimited between the walls 20 and 19, and one portion outside of the wall 20 inside the channel 15.
Likely water leaks that may occur between the wall ends 19, not welded to each other, will not be dispersed in the device I and consequently in the wash tub, since they are contained in the recess 18.
From the above description the features of the present invention are clear.
In particular, a device for supplying liquid in the tub of a household washing machine, particularly a dishwasher, has been described, which device is of simple, compact, low-cost manufacture, and ensuring, in respect of the know realization, an improved performance reliability as well as an easier, cost-effective production.
In a preferred embodiment of the present invention are provided means for detecting leakage due to a defective welding both outside and inside the device.
From the above description also the advantages of the present invention are clear; in particular the following advantages should be pointed out:

its manufacturing simplicity, since an additional component is removed;
automatic moulding and welding of both half-shells, having no additional internal components;
verification of all welding points of both half-shells;
absolute reliability of the device at the washing machine manufacturer's and consequently for the end user.

It is obvious that many changes are possible for the man skilled in the art to the device for supplying washing liquid in the tub of a household washing machine, in particular a dishwasher, described above by way of example, without departing from the novelty spirit of the invention.
According to a possible embodiment, the removal of the additional component required for the air break, allows manufacture of the device in one piece alone by means of the blow moulding process. Thus, welding is no longer required with a consequent obvious reduction of manufacturing costs.
Moreover, both a double rib on the outer wall and inner ribs for a welding test channel are no longer required, with a consequent clear reduction of material and relevant costs.
It is obvious that many other changes are possible for the man skilled in the art to the device for supplying washing liquid in the tub of a household washing machine, in particular a dishwasher, described above by way of example, without departing from the novelty spirit of the invention.

Claims

A device for supplying washing liquid to a household washing machine, in particular a dishwasher, said device (1) having a body (2) consisting of two parts (2A,2B) substantially mirror-like welded to each other, where inside of said body (2) one or more functional elements (3,4,6,9,13,14) are delimited, such as:

a water non return device to the waterworks, and/or

at least a chamber (4) for collecting water, in particular required for regeneration of the softening resins of the washing water, and/or

at least a vent (14) directed to the outer environment, and/or

at least an outlet column (13) for the steam coming from the wash tub of the machine, said column (13) being in communication with said tub through an opening (12), and/or

at least a duct (6;9) to let water flow through,

wherein one or more of said functional elements (3,4,6,9,13,14) is at least partially formed or delimited inside of said body (2) by portions of said two parts (2A,2B) welded between them;
characterized in that are provided means (15) for ensuring verification or control of the efficiency condition of all weld areas between said two parts (2A,2B) located inside said body (2).
A device according to claim 1, characterized in that said means (15) are additionally provided for allowing checking or control of the efficiency state of all welding areas between said two parts (2A,2B) facing outside said body (2).
A device according to claim 1 or 2, characterized in that said means (15) comprise at least a channel (15) apt for containing a fluid under pressure.
A device according to claim 3, characterized in that said channel (15) has at least a wall (15A,15B) delimiting the outer perimeter of said body (2).
A device according to claim 3, characterized in that said channel (15) has at least a wall (15A,15B) delimiting one or more of said functional elements (3,4,6,9,13,14).
A device according to claim 4, characterized in that said wall (15A,15B) is formed by two portions of said two parts (2A,2B) welded to each other.
A device according to claim 5 or 6, characterized in that said wall (15A,15B) delimits said chamber (4) for collecting water.
A device according to claim 5 or 6, characterized in that said wall (15A,15B) delimits said column (13) for steam outlet.
A device according to claim 5 or 6, characterized in that said wall (15A,15B) delimits said duct (6;9) for the water to flow through.
A device according to claim 3, characterized in that said channel (15) has a continuous closed volume trend.
A device according to claim 3, characterized in that said channel (15) is an integral part of said device (1) for liquid supply.
A device according to claim 5 or 6, characterized in that said wall (15A,15B) forming said channel (15) has a continuously development without any interruptions.
A device according to claim 9, characterized in that said wall (15B) delimiting said duct (6) has at least a recess (18) apt for containing a welding flash (21).
A device according to the previous claim, characterized in that said recess (18) is restricted to a portion of said wall (15B), in particular at the end of said water non return device (3) to the waterworks.
A device according to at least one of the previous claims, characterized in that one side (19) of said recess (18) has a lower height than the opposite side (20).
A device according to one or more of the previous claims, characterized in that said body (2) contains no additional components on the inside.
A device for supplying washing liquid to a household washing machine, in particular a dishwasher, said device (1) having a body (2) wherein are delimited one or more functional elements (3,4,6,9,13,14), such as:

a water non return device to the waterworks, and/or

at least a chamber (4) for collecting water, in particular required for regeneration of the softening resins of the washing water, and/or

at least a vent (14) directed to the outer environment, and/or

at least an outlet column (13) for the steam coming from the wash tub of the machine, said column (13) being in communication with said tub through an opening (12), and/or

at least a duct (6;9) for the water to flow through;

characterized in that said body (2) is obtained in one piece alone.
A device for supplying washing liquid to a household washing machine, in particular a dishwasher, said device (1) having a body (2) wherein are delimited one or more functional elements (3,4,6,9,13,14), such as:

a water non return device to the waterworks, and/or

at least a chamber (4) for collecting water, in particular required for regeneration of the softening resins of the washing water, and/or

at least a vent (14) directed to the outer environment, and/or

at least an outlet column (13) for the steam coming from the wash tub of the machine, said column (13) being in communication with said tub through an opening (12), and/or

at least a duct (6;9) for he water to flow through;

characterized in that said water non return device (3) to the waterworks is obtained without any additional means.