DEVICE FOR A DISH-WASHER

Abstract: This invention relates to a device for a dish-washer comprising a tub with a bottom (10) which is provided with a sump (11) for collecting liquid circulating in the tub. When the machine is emptied, the liquid is distributed from the sump to the inlet side of a sewage pump (20) from which the liquid is discharged to a sewage or the like. In order to make the overall height of the machine small to limit the quantity of water remaining in the sump and to considerably decrease the working time of the pump for reaching this small quantity the bottom surface of the sump (11) is placed below or on the same level as the pump housing (23) and the inlet (21) of the pump is via a pipe (17) having rest­ riction (26) communicating with the sump.

Description: This invention relates to a dishwasher comprising a tub with a bottom which is provided with a sump for collecting liquid circulating in the tub the bottom surface of the sump being situated below or on the same level as a housing of a pump, the inlet of the pump being provided with a pipe connection communicating with the sump and having an outer part whose axial direction is mainly vertical and an inner part whose axial direction is mainly horizontal the pipe connection also being provided with a restriction. Dishwashers of this type are previously known, see US -A-2 681 658. However the pump arrangement is solely used for the circulation pump in order to make the pump accessible from the inside of the tub. Dishwashers usually are so designed, see the abovementioned publication, that the liquid, which usually is water, via a hose by means of gravity flows from the sump to the sewage pump which is placed below the bottom of the tub. This usually is a reliable method safeguarding that the remaining quantity of water is minimized which is desirable in order to prevent that water remains in the tub and pollutes the fresh water which is taken in during a following dishcycle. The above arrangement is used for machines which are placed on the floor as well as on the bench. However the arrangement has a drawback - in particular on machines which are placed on a bench where it is important to restrict the overall dimensions of the machine as much as possible for a given size of the tub - since the overall height of the machine becomes much larger than the height of the tub because of the disposal of the pump. DE 2 428 941 shows a dishwasher having a pump placed outside and above the bottom of the tub. According to this arrangement the inlet side of the pump is connected to the tub by means of a conduit which has a check-valve preventing the water in the outlet hose and in the pump from flowing back into the tub. Such an arrangement is however not reliable since there is a risk that particles in the water flow get stuck on the valve seat thereby preventing the valve body from closing. Moreover since the outlet of the tub has a comparatively large diameter air will be sucked into the pump before the level sinks to the bottom surface. It is also known to place a circulation pump in a dish-washer beside the sump - see FR 2 425 228 - and to connect the pump with the sump by a knee-shaped pipe. In order to use a small quantity of water during the washing procedure the inlet opening of the pipe is placed close to the bottom of the sump and the bottom is shaped so that the flow into the pipe is facilitated. However no measurements have been taken to safeguard that the water from the inlet side of the pipe is distributed into the pump. The purpose of this invention is to create an arrangement where the height of the dish-washer is limited, where the remaining water quantity when emptying the machine is as small as possible and where the working time of the pump for creating this small quantity is considerably reduced. This is achieved with a device according to the invention and having the characteristics mentioned in the claim. An embodiment of the invention will now be described with reference to the accompanying drawings in which Fig. 1 is a vertical section of the lower part of the tub with the sewage pump whereas Fig. 2 is a graph showing the remaining water quantity as a function of the working time of the pump. As appears from Figure 1 10 is the bottom of the tub which is provided with a sump 11 in which the water circulating in the machine is collected. From the sump 11 an edge part 12 extends vertically upwards and continues via a mainly flat surface 13 into the wall 14 of the tub. The edge part 12 has a hole 15 which forms a cylinder shaped sealing surface 16. Through the hole 15 a pipe 17 is inserted. The pipe has an outer mainly vertical part 18 and an inner mainly horizontal part 19. The end of the inner part has a collar so that a socket for the inlet to the sewage pump 20 is formed. The inlet of the pump is shaped as a sleeve 21 which is inserted in the collar end of the pipe 17. Between the pipe 17 and the sealing surface 16 there is an O-ring 22 by means of which the tub is sealed from the surrounding. The inlet sleeve 21 of the pump 20 continues into a pump housing 23 in which an impeller 24 rotates in the usual way and distributes the water to an outlet 25 from which it by means of a hose is distributed to a sewage. The pipe 17 which preferably is made of plastic has a restriction comprising a wall part 26 extending vertically upwards from the area 27 where the vertical outer part 18 continues into the horizontal inner part 19. Preferably the restriction area of the wall part 26 is somewhat less than half the area of the inner pipe section. The inlet 28 of the pipe connection 17 is placed a short distance, preferably 3 - 8 mm, from the bottom of the sump 11. This means that the lower part of the pump housing 23 is placed at mainly the same height as the inlet 28 of the pipe connection 17. The outer shell of the dish-washer is in the Figure marked with 29 and it appears from the Figure that the distance between the bottom of the dish-washer and the shell can be minimized by the arrangement. The importance of the wall part 26 appears from the graphs in Fig. 2 where the dash-dotted line shows the remaining quantity R of water as a function of the working time T of the sewage pump with a pipe connection without any wall part whereas the full line shows R and T with the pipe connection having said wall part. From the graph it clearly appears that it is possible to decrease the emptying time by means of the restriction wall from 60 to 30 sec. for a given remaining water quantity of 1 dl. This might depend on that the pump during the final period of the emptying procedure, that is when air begins to flow into the inlet 28, distributes the water step by step. Thus the wall part 26 prevents the water which is successively thrown up into the pipe 17 from flowing back to the sump 11 but this water will temporarily fill the pump housing and then be forced to its outlet.

Claims: Dishwasher comprising a tub with a bottom which is provided with a sump (11) for collecting liquid circulating in the tub the bottom surface of the sump being situated below or on the same level as a housing (23) of a pump, the inlet (21) of the pump being provided with a pipe connection (17) communicating with the sump and having an outer part (18) whose axial direction is mainly vertical and an inner part (19) whose axial direction is mainly horizontal the pipe connection also being provided with a restriction (26), caracterized in that the pump is a sewage pump which distributes the liquid from the sump (11) to a sewage, that the outer part has no restriction but that the restriction (26) of the pipe connection is a wall part extending mainly vertically upwards from the pipe connection (17) at its inner part (19). Device according to claim 1, caracterized in that the wall part (26) is placed at the intermediate area (27) between the outer and the inner part (18 and 19 resp). Device according to any of claims 1 - 2, caracterized in that the surface of the wall part is less than half the inner section area of the pipe. Device according to any of the preceding claims, caracterized in that the lower limiting surface of the pump housing (23) is placed mainly at the same level as the inlet (28) of the pipe connection.

Inventors: STRIDH, KEIJO AULIS, TOLF, ANDERS KARL HENRIK
Applicants: AKTIEBOLAGET ELECTROLUX
Application year: 1990
Main classification: A47L15
IPC codes: A47L15