WASH TUB FOR DISHWASHERS

Abstract: A wash tub (3) for dishwashers has a rectangular cross-section and houses a spray arm (5) rotatable about an axis (10) adjacent to the centre of said cross-section. The larger side walls (12) of the tub are provided with recesses (11) capable of receiving the end portions of the spray arm during rotation thereof. The length and washing effectiveness of the rotary spray arm (5) is increased.

Description: The present invention relates to a wash tub for a dishwasher, particularly to a household dishwasher. Household dishwashers are usually provided with a tub forming a washing chamber of parallelepipedonal shape having an open side which can be closed by means of a loading door. The tub houses one or more spray arms which are mounted rotatably about a vertical axis. The tub generally has a horizontal square cross-section. The spray arms having a length which is slightly smaller than the horizontal extension of the side wall of the tub. In this construction the spray arms are of maximum possible length, but still not highly effective in the corner parts of the tub. Some of the modern household dishwashers are of reduced size and do not have a square horizontal cross-section. In these dishwashers the spray arms have a length which is smaller than the extension of the smaller side wall. This furthermore reduces washing effectiveness. US-A-40 64 887 shows a dishwasher of the above kind, where the side walls are not plane over the entire area but have inwardly projecting parts which serve as tracks for supporting a dishrack The object underlying the invention is to provide for an optimum washing effectiveness in a dishwasher having a wash tub of rectangular cross-section. This object is solved by the characterizing features of claim 1. A preferred embodiment is referred to in claim 2. The features and advantages of the present invention will become more evident from the following description, which is only given as a non-limiting example, with reference to the accompanying drawings: Figure 1 diagrammatically shows a longitudinal section of a dishwasher provided with a tub forming a washing chamber according to a preferred embodiment of the invention; Figure 2 diagrammatically shows a cross-section of the dishwasher of Figure 1, taken along lines II-II. With reference to figures 1 and 2, the tub 3 is housed in a support cabinet 4 of a dishwasher and is interiorly provided with a lower rotary spray arm 5 and an upper rotary spray arm 6. In a traditional way, the spray arms 5 and 6 are capable of sprinkling the crockery (not shown) which is supported on relevant baskets 7 and 8. The tub 3, and the cabinet 4 of the dishwasher is of parallelepipedonal shape with an open front side which can be closed by means of a loading door 9 (see Figure 2). The tub 3 has a rectangular horizontal cross-section, and the axis of rotation 10 of the spray arms 5 and 6 clashes With, or is adjacent to the center of such a rectangular cross-section. As shown in Figure 2, the axis of rotation 10 preferably stands backwards with respect to the door 9. The larger side walls 12 of the tub 3 are provided, at least in correspondence of the plane of rotation of the lower spray arm 5 (which plane could even be inclined), with relevant recesses 11 capable of receiving the end portions of the same spray arm 5 during rotation thereof. Preferably, the recesses 11 each have a cross-section in the form of a circular segment concentric to the axis of rotation 10 of the lower spray arm 5. It is, thus, possible to use a spray arm 5 which is longer than the shorter sides 13 of the cross-section of the tub 3. As a consequence, the area of such a cross-section which is not swept by the spray arm 5 during its rotation (this area being hatched in figure 2) is advantageously reduced at a minimum. Of course, this results in the items supported by the basket 7 being more effectively washed; as is known, these items are usually more soiled than the ones supported by the upper basket 8. Obviously the dishwasher described above may undergo several modifications without departing from the scope of the present invention as defined in the appendent claims. For instance, the upper spray arm 6 may be as long as the lower spray arm 5; in this case the tub 3 may be provided, at a suitable height, with further recesses in its larger side walls 12, like recesses 11. As an alternative, the recesses 11 shown in Figure 1 may extend upwards at least until the plane of rotation of the upper spray arm 6. Of course, it is also possible that the recesses 11 are only provided in correspondence of the upper spray arm 6. Finally, it is to be noted that the dishwasher according to the invention may be constructed in every other size, whenever it is desired to use rotary spray arms having an increased length and, consequently, an increased washing effectiveness.

Claims: Wash tub for a dishwasher of substantially parallelepipedonal shape, having a rectangular cross-section, the tub (3) housing at least one spray arm (5,6) which is mounted rotatably about a vertical axis (10) extending adjacent to the centre of said cross-section, characterized in that the spray arm (5) is longer than the shorter side (13) of the cross-section, and that the larger side walls (12) of the tub (3) are provided at least in the plane of rotation of the spray arm (5) with recesses (11) to allow free rotation of the spray arm (5). Wash tub according to claim 1, characterized in that said recesses (11) each have a cross-section in the form of a circular segment concentric to the axis of rotation (10) of the spray arm (5).

Inventors: SGOBARDO, ROBERTO, TASSOTTI, SERGIO
Applicants: INDUSTRIE ZANUSSI S.P.A.
Application year: 1988
Main classification: A47L15
IPC codes: A47L15