CA1148838A - Warewasher bypass soil collector - Google Patents

Abstract

WAREWASHER BYPASS SOIL COLLECTOR
Abstract of the Disclosure A warewasher such as a domestic dishwashing machine has a first recirculating path for recirculating wash and rinse fluids through nozzles which spray the fluid onto food ware items in the wash chamber of the warewasher. Fluid is also circulated from the wash chamber through a fluid bypass circuit which bypasses the spray nozzles and conducts fluid to a soil collector which is separated from the wash chamber. The soil col-lector removes food soil debris from the fluid and holds it for discharge into the warewasher drain system when the fluids are drained from the warewasher.

Description

WAREWASHER BYPASS SOIL COLLECTOR
Back~round of the Invention The present invention relates to warewashing machines, and more particularly to domestic or household-type dishwashers. Food ware items are cleaned in suchmachines by a sequence of one or more wash and rinse periods under the control of a timer. During a wash period, water and detergent are introduced into the wash chamber of the warewasher, and this wash fluid is sprayed under pressure onto the food ware items by a recirculat-ing pump which pumps the wash fluid through the nozzles of a rotating wash arm system. At the end of each wash period the soiled wash fluid is drained. For rinsing, clean water alone is introduced into the wash chamber, and this rinse fluid is also recirculated and sprayed onto the food ware items, and then drained. Normally, several rinses are required.
Such machines ~enerally have several different operational modes or "cycles", with the number of wash and rinse periods for each being determined by the soil conditions and the quantities or types of articles typic-ally washed in such a cycle. For example, a dishwasher such as shown in U.S. Patent 3t549l294 (assi~ned to the assignee of the present invention) enables the machine operator to select any of several wash cycles having different time periods and different numbers of wash and rinse periods. In the '294 machine, a Normal Wash is typicallv used to clean dishes, glasses, and other dinnerware, while a Soak Cycle is preerably used for removin~ heavily baked-on encrustations from pots, pans, or casserole dishes which have been used in cooking or baking. While the total quantity of soil removed during any particular cycle is related, of course, to the number of food ware items placed within the warewasher and the extent to which the machine operator may already have scraped food soil from the items before placing them J~ 3~3 in thP warewasher, it is normally expected that moresoil will be removed during a Soak Cycle than during a Normal Cycle. As a result, a Soak Cycle will typically include more wash and/or rinse periods than a Normal Cycle.
The need for several wash and rinse periods results from using the same single wash chamber and recirculating and spraying system for both the washing and rinsing phases of the warewashing operation~ No matter how well the fluid may be filtered as it is used, some of the food soil debris unavoidably becomes suspended within the fluid and then passes continually through the recirculating pump and spraying system as the fluids are being sprayed onto the food ware items. Many of these food soil particles are then redeposited onto the food ware items as they are being washed and/or rinsed.
Some also remain behind on the walls of ~he wash chamber and within the recirculating pump and spray arms. Multiple rinse periods help reduce this redeposit problem, since, during each rinse period, fresh water is introduced, sprayed, and then drained, so that less and less of this fine soil remains, and less and less is redeposited.
There are two principle methods or theories of washing dishes in a domestic dishwashing machine.
In one, the fluid which is sprayed onto the food ware items is first finely filtered of soil, to enable the uye of small wash arm orifices (typically as small as 4mm across) and a fairly high pressure pump. Without fine filtering, small orifices and acceptably sized pumps could not be used, and high spray pressures and velocities could not be reliably achieved, due to the likelihood of cloggin~ such small orifices. A small orifice/high pressure system therefore usually re~uires a fine filter for capturing rather than recirculating the soil. Such a system also typically uses two pumps, one for pumping the filtered fluids through the wash arms, and another, located essentially upstream of the filter, for pumping the water and collected soils to a drain at the end of a wash or rinse period.
In the other method or theory of washing dishes, only a single pump is required for both spraying and draining. There is no fine filter to capture and remove the soil from the recirculating fluid. Instead, the soil is essentially recirculated continuously (except, of course, for the soil particles which are just too large for the pump and spray system to handle. These must eventually be removed manually). The wash arm spray orifices in such a non-filtering system are necessarily much larger ~typically 7mm) to permit passage of the larger soil particles without clogging the orifices.
lS Larger quantities of fluid may therefore be pumped, but usually at lower pressures. Since the soil is substan-tially continuously recirculated along with the fluid, due to the absence of a fine filter in such a system, it is repeatedly subjected to forces which break it up and disintegrate it much more quickly than in systems using a fine filter. This produces a much larger quantity of fine soil particles, which are proportionately more difficult to remove from the food ware items and the warewasher itself, unless a correspondingly larger number of rinse periods is used than is customary in systems employing fine filters.
Even with systems employing a fine filter, however, the recixculating fluid necessarily passes through the debris which has been captured by the filter. In heavy soil conditions, it is possible for the fluid flow to become sufficiently obstructed at the filter, as by partial clogging thereof, to impair the efficiency and effectiveness of the recirculating and spraying system.
It is therefore desirable to remove as much of the soil as possible to a remote location separated from the recir-culating and spraying system. This not only prevents ~FN 6555 -5 clogging of the recirculating and spraying system, but also minimizes disintegration and emulsification of the food soil at the filter, caused by turbulence in the fluids, which continuously agitates the collected food soil debris.
The general principle of separate soil removal is widely recognized in a number of other fields. For example, in many oil-lubricated machines, such as internal combustion engines, in which the lubricating oil is recirculated, a portion thereof is circulated through a bypass filter, thus extending the effective life of the lubricant and of the engine or machine itself.
Similarly, in the clothes washing art, an auxiliarly water recirculating path is often provided to pass some of the water through a lint filter for subsequent separate removal.
Thus, the more soil which is removed from the primary recirculating and spray system within the ware-washer~ and the faster it is removed, the fewer wash and~or rinse cycles, and hence the less hot water, that will be required. Further, by "extending" the usefulness of the water, early soil separation and removal can reduce the amount of hot water needed in each particular period~
As a result, considerable energy and resource savings can be realized both in the quantity of water consumed during each wash or rinse period, and in the total number o periods required.
The prior art relating to domestic dishwashing machines includes several examples of filters intended to supply the advantages of a bypass filter in accordance with the above discussion. However, they are generally only partially effective, or require servicing by the machine operator, or both. Preferably, such a system should remove large as well as small soil particles from the recirculating and spray system as quickly as possible (without first requiring them to pass through the 3~3 ~FN 6555 -6-recirculating spray system itself), and should flush them completely down the drain during draining of the fluid from the warewasher, with essentially no intervention or assistance from the machine operator.
SuT~nary of the Invention Briefly, the present invention meets the above needs and purposes by providing an inexpensive, highly effective fluid bypass circuit which draws the wash and rinse fluids from the bottom of the wash chamber, passes them through a bypass soil collector, and returns the filtered fluid ("supernatant") back to the wash chamber - of the warewashing machine.
The fluid bypass circuit is independent of and bypasses the primary spray means within the wash chamber. That is, a typical domestic dishwasher will have one or more spray arms which receive pressurized wash and rinse fluids from the recirculating pump and spray the fluids onto the food ware items within the wash chamber of the dishwasher. In such a machine, the wash arms are the primary spray means since they are responsible for and provide the pressurized fluid spray which impinges on the food ware items to clean and rinse them. Some warewashing machines also include other spray-ers or sprinklers to supplement the action of the primary spray rneans, and these can be distinguished by the fact that the manufacturer would consider the supplementary spray members to be helpful but not essential for satis-factory operation of the dishwasher, while the primary spray means is considered essential and necessary.
In the preferred embodiment, the dishwasher has a circulating system consisting of two pumps, a recir-culating pump and a drain pump, and the recirculating pump and primary spray arrns can therefore be independent of the fluid bypass pump and bypass soil collector.
The present invention can also be used in a warewashing machine having but a single pump, but when two pumps /

fB&~3 are used, the recirculating pump does not h~ve to supply fluid for the bypass soil collector~ Instead, it is reserved for supplying hiyh pressure wash and rinse fluids to the spray arms alone, and the drain pump is utilized S to supply fluid independently to the fluid bypass circuit, through the soil collector, and back to the wash chamber.
The soil collector is located in a portion of the fluid bypass circuit which is separated from the wash chamber, in order to remove the food soil debris from the wash chamber as quickly as possible, to retain it outside the wash chamber, and to protect it from the emulsifying and disintegrating forces of the wash and rinse fluids within the wash chamber as they are being distributed by the primary spray arms. In this sense, the soil collector could be inside the actual dishwasher tank as long as the soil collector defined a protected volume or space which was separated from the remaining -volume of the tank. In that case, it would not be possible to place food ware items within the volume of the soil collector, so the volume of the soil collector would not form a portion of the volume of the wash chamber.
Instead, the volume of the tank would actually be greater than the volume of the wash chamber. However, in order not to reduce the available wash chamber volume, it is preferable to locate the soil collector entirely outside the wash tank of the warewashing machine.
In the preferred embodiment, the inlet to the fluid bypass circuit is at the very bottom of the wash chamber. A dishwashing machine will usually have a sump, and the inlet to the fluid bypass circuit will then be at the bottom of the sump. Since much of the food soil debris which is washed from the food ware items tends to settle to the bottom of the wash chambe~, the fluid bypass circuit and soil collector will remove this debris very quickly. In fact, the amount of food soil debris which is removed will usually be greater, in proportion to the fluid flowing through the fluid bypass circuit, BFN 6555 -a-for these very reasons.
Another advantage of the independence of the fluid bypass circuit from the primary spray means is that the fluid bypass circuit and soil collector can accept large pieces of food soil debris, much larger than could be allowed to enter the spray arms. The latter can accept particles no larger than the spray orifices therein or the spray nozzles will become clogged. On the other hand, the fluid bypass circuit and soil col-lector can accept food soil debris sizes close to thesize of the drain line in the dishwashing machine.
It is also an advantage of the present inven-tion, however, that it can be used on dishwashers having but a single pump. In such a case, the output of the recirculating pump would be divided, the largest portion going to the primary spray means, and a bypass portion going through the fluid bypass circuit, the soil collector, and then directly back to the wash chamber independently of the primary spray means. Thus, even though a single pump must necessarily restrict the permissible food soil debris intake sizes to smaller dimensions, the use of the present invention with such a single pump would still provide substantial advantages. The spray arms and soil collector could each be optimized to provide the best performance independently of the other, and the food soil debris would be removed and isolated early and quickly.
The soil collector is operable in two modes, a soil collecting mode and a soil discharging mode. In the soil collecting mode the wash or rinse fluids are circu-lated to the soil collector,-which removes the food soil debris from the fluids and collects and holds the debris for subsequent discharge from the warewashing machine. In the soil discharging mode the collected food soil debris is discharged from the soil collector. The soil collector is operated in the soil discharging mode whene~er the drain system of the warewashing machine is draining the r~

wash or rinse fluids out through the drain line. Whendraining is taking place, the soil collector discharges the collected food soil debris so that it passes directly out through the drain line. At the other times that the wash and rinse fluids are being recirculated within the warewashing machine, the soil collector is operated in the soil collecting mode to provide simultaneous and continuous cleaning of the fluids by the soil collector.
In the preferred embodiment, the soil collector includes a soil collector body having an upwardly open hollow interior which is attached to the underside of a correspondingly shaped opening in the wash chamber bottom. A fine mesh screen is mounted at the interface between the soil collector body hollow interior and the wash chamber opening, the screen and the upwardly open hollow interior of the collector body defining a soil collecting compartment. As will be seen, the fluids cir-culating in the fluid bypass circuit are forced to flow through the fine mesh screen, which thus serves as a separating means to separate the food soil debris from the fluid. The fine mesh screen also serves as the fluid outlet for the soil collector body.
The soil collector body has a fluid inlet conduit and a debris outlet conduit which merge into a common opening at the bottom of the hollow interior, and the hollow interior bottom is sloped downwardly toward this common opening. As the fluid inlet conduit merges with the debris outlet conduit, they are shaped to form a venturi which develops a slight negative pressure in the debris outlet as fluid is forced through the fluid inlet conduit and through the venturi. This acts as a hydraulic check valve, having no movin~ parts, which keeps the collected debris within the collector body compartment while the soil collector is operating in the soil collecting mode. When it is time to drain fluid from the warewasher, a diverter valve diverts the output BFN 6555 -10~

of the drain pump ~rom the fluid inlet of the soil col-lector to the drain line of the warewashing machine~
This discontinues operation of the venturi, and as the fluid level within the warewashing machine drops, the ~luid in the soil collecting compartment flows out through the debris outlet~ carrying the collected food soil debris with it.
The debris outlet conduit opens directly opp-osite the inlet to the drain pump, so that the debris is entrained in the fluid which is being drawn into the drain pump. This carries the debris directly out through the drain line without dispersing it back into the wash chamber. As the food soil debris is being discharged through the drain line, cleaning of the fine mesh screen is facilitated by a fluid spray jet on one of the wash arms which directs a back~flushing spray against the upper side of the fine mesh screen, somewhat similar to that shown in U.S. Patent 4,038,103, assigned to the assignee of the present invention.
If the machine operator should interrupt opera-tion during the wash or rinse portion of a machine cycle, thereby stopping operation of the pumps, the soil collector body is located below the normal static level of the fluid in the wash chamber. Thus, there will be no move-ment of fluid into or ollt of the submerged soil collector body, and the collected food soil debris will remain in the soil collector compartment. On the other hand, after the wash and rinse fluids have been fully drained from the warewashing machine, the soil collector will also be fully drained of fluids, so that a "broth" is not left behind in which bacteria might develop between dishwashing operations.
It is to be expected that there will be food soil debris introduced into the warewashing machine that will be too large for the recircu]ating and spray system, and some which will be too large for the drain pump and , . ' ' ! ' ~

soil collector in the fluid bypass circuitO Also, the debris which is removed by the bypass soil collector, regardless of its size, will not all be removed at once.
Thus, in the preferred embodiment, a relatively fine filter is provided in the fluid inlet path for the recir-culating pump and spray arms. That filter is principally to prevent ~ood soil debris from clogging the water spray jets on the spray arms, and not for the purpose of remov-ing fine food soil for controlling ~ndesirable redeposits.
Thus, the recirculating system filter does not materially interfere with or obstruct operation of the primary spray system.
Although the drain systQm can accept larger food soil debris particles than the recirculating system, it too has upper limits. The inlet to the drain pump is therefore provided with a food waste comminuter or disposer for reducing large-sized food soil debris part-icles to sizes which can be safely discharged out of the machine through the drain line. These particles are then forcibly pumped directly into the soil collector compartment, and trapped therein by an extremelY fine mesh screen (having holes 0.3mm diameter) as described above. The drain pump and disposer are operated contin-uously while the fluids are being recirculated during washing or rinsing of the food ware items. This provides the disposer with the maximum opportunity to do its job, that of comminuting and reducing large food soil particles to sizes suitable for passage through the fluid bypass circuit. Further, since the disposer is in the fluid bypass circuit upstream of the soil collector, it will pass the comminuted food soil particles but a single time to the soil collector. This debris reduction and removal starts immediately and continues throughout the period that the fluids are being sprayed onto the food ware items and the food soil debris is being removed therefrom, thereby providing for more effective soil ~FN 6555 -12-reduction than in systems where operation of the disposer is effectively limited to short drain periods. The im-mediate removal of the debris by the fluid bypass circuit following the reduction avoids the unnecessary and exces-sive disintegration of the debris which would resultif the reduced debris were simply recirculated.
Due to the operation of the ventur, a secondary pumping action is provided which causes some food soil debris to be drawn directly into the soil collector com-partment through the debris outlet conduit. This venturi-powered secondary pumping action further increases the rate of soil removal.
Thus, the present invention provides very effective early soil removal which is independent of the primary spray means. The principal aspect of the invention is to separate soil from the recirculating wash or rinse water, collect the soil at a point removed from the main dishwashing operation, and subsequently dispose of the collected soil down a sewer or drain, preferably by pumping it under positive pressuxe to a sink drain or a food waste disposer connected to the sink drain, and simultaneously cleansing the soil col-lector for its next use. Soil collection in this manner improves main recirculating pump efficiency and obtains ~5 better washing results. Redeposit is substantially reduced, permitting a substantial reduction in water usage. The captured food soil debris can be disposed of on command (by switching to the soil discharging mode). Thus, disposal of collected food soil debris may be accomplished at the end of each wash or rinse period, when the sump is drained. Or, with several embodiments~ during an early wash period while soil is being collected in large quantities, soil can be ejected to the sewer in spurts or pulses while draining only a small amount of water from the sump.
As a result of the early soil removal, the 3~3 ~FN 6555 13-present invention enables the washing of dishes, pots, and pans with baked-on soils, etc. under heavy or gross soil conditions, with a smaller number of wash and rinse periods than previously possible. The reduction of the number of wash and rinse periods (and the utilization where possible of a smaller quantity of water for each such period~ results in reduced water consumption and inherently, where hot water is involved, a reduction also in the energy which would have been used to heat the water which has been saved. This improvement in washing effi-ciency, although using less water, is actually accompanied by an improvement in washing effectiveness.
Virtually no moving parts are re~uired in the preferred embodiment, and the invention is self-cleaning without requiring manual assistance. It is also very tolerant of overload conditions. That is, if the soil collecting compartment in the soil collector body should become filled, this will not interfere with operation of the primary spray means. The high pressure washing and rinsing sprays will continue to be provided for clean-ing the food ware items within the warewashing machine, and the collected food soil debris will be discharged into the drain line at the end of that particular wash or rinse cycle. The venturi check valve of the preferred embodiment will serve as a pressure relief valve during such an overload condition to limit the pressure which develops within the soil collecting compartment of the soil collector body. Thus, excess pressure will not be developed which might extrude some of the collected food soil debris through the fine mesh screen.
It is therefore an object of the present inven-tion to provide an improved warewashing machine, such as a domestic dishwasher, having a fluid bypass means which is independent of and bypasses the primary spray means to conduct fluid from the wash chamber through a soil collector which is separated from the wash chamber, to remove, collect, and hold the debris thereat and to return the resulting supernatant to the wash chambex independently of the primary spray means; to provide such a combination in which the soil collector can be operated in both a soil collecting and soil discharging mode; in which the soil discharging mode causes the col-lected food soil debris to be ~ischarged through the drain line; in which the removed food soil debris is protected from disintegration and emulsification due to recirculation and spraying of wash and rinse fluids onto the food ware items; in which the food soil debris is removed directly from the wash chamber without first having to pass through or be propelled by the primary spray means; and to provide the above objects and purposes in an inexpensive, versatile, and reliable configuration readily suited for use in a wide variety of warewashing machines whether equipped with a single pump or a plural-ity of pumps~
Other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims.
Brief Descript~on of the D awi~
Fig. 1 is a partially broken away cross-sectional view of a domestic dishwashing machine including a bypass soil collector according to the present invention;
Fig. 2 is a cross-sectional view of the soil collector shown in Fig. 1, taken on line 2-2 in Fig. 3;
Fig. 3 is a top view of the Fig. 1 soil collector;
Fig. 4 is a cross-sectional view of the Fig.'l soil collector taken on line 4-4 in Fig. 3;
Fig. 5 is a fragmentary cross-sectional view of the Fig. 1 soil collector taken on line 5-5 in Fig. 3;
Fig. 6 is a fragmentary cross-sectional view of the Fig. 1 soil collector taken on line 6-6 in Fig. 2;
Fig. 7 is a somewhat diagrammatic illustration showing the flow paths of the fluid through the Fig. 1 soil collector and the dishwashing machine sump during a wash or rinse period in the machine cycle;

B

FigO 8 is a view similar to Fig. 7 showing move-ment of the fluid during a drain period;
Fig. 9 is a cross-sectional view similar to Fig. 2 of another embodiment of the invention;
Fig. 10 is a view of the Fig. 9 embodLment analogous to Figs. 3 and 6;
Fig. llis a partially broken away cross-section-al view of a domestic dishwashing machine incorporating another embodiment of the present invention;
Fig. 12is a cross-sectional view of the soil collector shown in Fig.ll ;
Fig. 13is a cross-sectional view of the Fig.ll soil collector taken on line 13-13 of Fiy.12 ;
Fig. 14 illustrates movement of fluids through the Fig. 11 soil collector;

'4 ~

Fig 15 is a chart illustrating a typical operational sequence or machine cycle for a domestic dishwashing machine incorporating a bypass soil collector according to the present invention; and Fig. 16 illustrates a variation on the Fig-15 cycle.
Description of the Preferred Embodiments With reference to the drawings, a warewashing machine 50, such as a domestic dishwasher, includes conventional upper and lower racks 51 and 52 for supporting food ware items, such as cups, saucers, plates, silverware, and so on, within a tank 54. Tank 54 substantially defines the rear~ bottom, sides and top of a wash chamber 55 within machine 50 where the washing and rinsing of the food ware items takes place. The front of chamber 55 is defined by a door (not shown) which closes tank 54 during washing and rinsing of the food ware items.
As shown and described in greater detail in U.S.
Patent No. 4,097,307, issued June 27, 1978, assigned to the assignee of the present invention, machine 50 also includes a fluid circulating means consisting in part of a recirculating pump 57, drain pump 58, and drive motor 59, mounted coaxially on a common drive shaft. A sump 60 in the bottom of tank 54 comprises part of wash chamber 55, and the recirculating pump 57 and drain pump 58 are posi-tioned within this sump. Drain pump 58 i5 part of a drain system which has an opening in the bottom of sump 60 for receiving and draining the wash and rinse fluids from the warewashing machine 50, through a drain line 61, and into a conventional household drain, for example.
In the embodiment shown in Fig. 1, the dxain pump inlet 63 (Fig. 4) is the inlet to the drain system.
The recirculating pump inlet 64 (Fig. 11) is located in sump 60 slightly above the drain pump inlet 63. Inlet 64 is protected by a filter screen 65 to prevent excess-ively large food soil debris particles from entering the recirculating pump 57 and blocking or clog ~ng the jet spray orifices on the upper or lower wash arm assem-blies 67 and 68. Wash arm assemblies 67 and 68 are theprimary spray means for cleaning the food ware items within machine 50, and are connected by suitable conduits to the outlet of the recirculating pump 57. It will be recognized that the description thus far of machine 50 is of well-known and conventional components usually found in high quality domestic dishwashing machines.
With reference to Fig. 1, the improvement of the present invention includes a bypass soil collect~r 70 which is independent of and bypasses the wash arm assemblies 67 and 68. Collector 70 is the preferred embodiment of the present invention and consists in part of a fluid bypass circuit 72 which includes a portion 73 separated from wash chamber 55. In the preferred ~ embodiment shown in Figs~ 1-8, the fluid bypass circuit 3~ 72 includes portions of the drain line 61, as well as the drain pump 58, which affirmatively conducts fluids through the fluid bypass circuit 72. The drain pump inlet 63 (Fig. 4) is the inlet for the fluid bypass cir-cuit 72, and is located substantially at the bottom of sump 60 to expedite removal of food soil debris as it settles to the bottom of the wash chamber 55. A soil ~ .

B~38 collector having a body 75 is also located in and formsa part of the fluid bypass circuit portion 73. As des-cribed more particularly below, soil collector body 75 has a fluid return outlet for returning the fluid back to the wash chamber. The fluid bypass circuit is thus connected to the wash chamber 55 for conducting fluid therefrom, through the fluid bypass circuit, and back to chamber 55 independently of the wash arm assemblies 67 and 68.
A diverter valve 78 is located in drain line 61 for selectably continuing passage of fluids through the drain line and out of the warewashing machine 50, or diverting the 1uid from the drain line to flow through fluid circuit portion 73 and thence back into the wash chamber. Diverter valve 78 is perferably under the control of a timer (not shown) which causes the diverter valve to divert fluids to flow through the fluid bypass circuit or to send the fluids out through the drain line 61. When the warewashing machine is operated in a washing or rinsing cycle, the fluid circulating means operates in a fluid recirculating mode in which it recirculates and sprays the fluids onto the food ware items. In this mode the diverter valve 78 is operated to divert the output of the drain pump 58 through circuit portion 73 and the soil collector body 75, causing the soil collector to operate in a soil collecting mode in which food soil debris is removed from the fluids circulating therethrough and held for subsequent removal, as further described below. When the warewashing machine is operated in a drain cycle, the fluid circulating means operate in a fluid draining mode. In this mode the diverter valve 78 is operated to send the fluids out of machine 50 through the drain line 61, and the soil collector is operated in a soil discharging mode to discharge th~ collected 3~ food soil debris into the drain system, as also further described below.

~ t~

With reference to Fig. 2, the soil collector body 75 includes an upwardly open hollow interior compart-ment 80, and is shaped to be attached to and to cover the underside of a wash chamber bottom opening 83. Open-ing 83 is roughly kidney shaped, and describes an arcof substantially constant radius from the vertical axis o~ rotation of the lower ~ash arm assembly 68. ~he bottom 84 of the hollow interior compartment 80 is sloped down-wardly toward an opening 85 thereinto which is a common opening shared by a fluid inlet conduit 87 and a debris outlet conduit 88, extending from one side of the soil collector body 75.
A fine mesh screen 90 at the interface between the soil collector body hollow interior compartment 80 and the wash chamber bottom opening 83 defines a fluid outlet from the soil collector body. The filter screen is in the fluid flow path which is connected by and through the hollow interior 80 between the fluid inlet 87 and the fluid outlet which the screen itself defines. Screen 90, which forms a portion of the boundary of compartment 80 in soil collector body 75, therefore acts as a separat-ing means to capture and retain food soil debris within the compartment 80, while allowing the resulting super-natant to pass out through the fine mesh screen separator/
outlet and back into the main wash chamber volume.
As best shown in Figs. 6 and 7, the fluid inlet 87 and debris outlet 88 are joined at angled with respect to each other, and are directed into the hollow interior 80 through the common opening 85, such that as fluid is pumped into the soil collector body 75 tArough the inlet conduit 87 by drain pump 58, the connection between inlet conduit 87 and debris outlet conduit 88 acts as a venturi 91 to creat a slightly negative pressure within the debris outlet conduit 88. At a minimum, this will retain fluids and debris within the hollow interior com-partment 80, and in normal operation will actually act BFN 6555 ~ B

as a secondary pump to cause a small reverse or inward flow of fluid through the outlet conduit 88 into the compartment 80, as shown in the Fig. 7 soil collecting mode flow diagram. The venturi may also be suitably modi-fied, if desired, to increase the secondary pumping actionto create a substantial reverse flow of fluid and debris through conduit 88 into compartment 80, thereby further increasing the rate at which food soil debris is removed by collector 70.
~s shown in Fig. 6 7 a preferred embodiment of the venturi 91 has the fluid inlet conduit 87 enter the debris outlet conduit 88 at an angle of approximately 30 degrees, and a distance of 5 cm from the common open-ing 85. The fluid inlet conduit 1 cm in diameter, the debris outlet conduit 2 cm in diameter, and the drain pump 58 normally causes the fluid to circulate through the fluid inlet conduit at a velocity of approximately 350 cm per second.
During operation in the soil collecting mode, the supernatant passes through the fine mesh screen 90 and reenters the wash chamber 55. The captured food soil debris remains behind and is collected in the com-partment 80 independently of the primary spray arm asse~-blies 67 and 68. Further, it remains in compartment 80 in a relatively quiescent state where it is protected from disintegration and emulsification due to recircula-tion and spraying of the wash and rinse fluids onto the food ware items by the primary spray arm assemblies 67 and 68. Capture and removal of the food soil debris is aided by a comminuter or food waste disposer plate 93 (Fig. 7) in drain pump 58, as shown more particularly in the above-noted U.S. Patent 4,097,307~ The bypass fluid circuit 72 enables disposer piate 73 and the drain pump impeller to comminute larger food soil debris part-icles continuously during the wash and rinse phases ofthe warewashin~ machine cycle. This affords the disposer BFN 6~55 -21-ror greater opportunity to do an effective job than would be the case if its operation were effectively restricted to the limited duration drain periodsO This combination also reduces and removes the food soil debris from the wash chamber, faster and more quickly t and with but a single pass through the disposer, for better and earlier capture by the bypass soil collector.
When it is time to drain the wash or rinse fluids from the warewashing machine 50, the diverter 1~ valve 78 is operated, as described above, to cause the fluids to flow out through the drain line and discontinue flowing through the fluid circuit portion 73 and soil collector body 75, as shown in the Fig. 8 flow diagram.
As the fluid level in wash chamber 55 recedes, the fluid and debris in compartment 80 flow downwardly across the sloped bottom 84 (see Fig. 2) and through opening 85 into the debris outlet conduit 88. Conduit 88 has a debris outlet 92 which is positioned to discharge the collected food soil debris and fluid as it leaves compart-ment 80 into the sump substantially adjacent the drainpump inlet 63. Thus, the food soil debris is entrained in the fluids in the sump 60 flowing into the drain system inlet as the debris is discharged from the soil collector body 75 while the fluids are being drained from the ware-washing machine 50. A shroud 9~ between outlet 92 andthe drain pump inlet 63 further guides the food soil debris directly from the former to the latter, to minimize dispersion of the discharged debris into the wash chamber sump 60 and to conduct the collected food soil debris from compartment 80 directly out through the drain line 61.
With reference to Fig. 2, the average static fluid level 98 is indicated, and is the approximate level which the fluid finds when the recirculating pump is stopped at the end of a wash or rinse cycle. Level 98 is thus also the level of fluid which a ma~hine operator 3~

would find upon interrupting a wash or rinse cycle when the machine is being operated. As may be seen in Fig~

2, level 98 is above the level of the soil collector body fluid outlet 90, defined by the fine mesh screen.
During such an interruption, therefore, the soil collector body 75 and its compartment 80 will remain entirely sub-merged. This means that there will be no fluid flow into or out of the soil colle~tor during such an interrup-tion, and the collected food soil debris will automatically be retained within compartment 80.
On the other hand, while fluid is being drained from the warewashing machine through drain line 61, sub-stantially all fluid will be simultaneously drained from the soil collector. This is a result of the sloped bottom 84 (Fig. 2) of compartment 80, and also the relative elevations (see Fig. 4) of the common opening 85, the debris outlet conduit 92, and the drain pump inlet 63.
That is, outlet 92 is below opening 85, and at least as high as inlet 63, so that the fluids readily flow downwardly out of compartment 80 and into the drain pump 58. As they flow out they carry the collected food soil debris directly into the drain line as described above.
A fluid spray jet 99 (Fig 4) is provided on the bottom of at least one of thè~arms of the lower wash 2S arm assembly 68. Jet 99 is positioned and aimed for spraying fluid onto the soil collector fine mesh screen 90 through the wash chamber bottom opening 83. This assists in flushing the soil collector compartment 80 with at least a portion of the fluid in the warewashing machine as the collected food soil debris is being dis-charged from the compartment 80 into the drain line 61.
That is, the inlet 64 to the recirculating pump 57 is located well below the average static fluid level 98.
Thus, during draining, fluid will continue to be avail-able at the recirculating pump inlet 64 until well afterhalf of the fluid within the wash chamber has been drained.

' I

~ ~ f~ 35;3 The recirculating pump 57 will therefore continue to operate during the first portion of a drain cycle, and fluid will continue to issue through the fluid spray jets, including jet 99, in the upper and lower wash arm assemblies 67 and 68. The fluid from jet 99 will therefore assist in flushing the food soil debris out of compartment 80 and out of machine 50 through the drain line 61.
The venturi 91 provides several advantages.
Principal among these is the absence of any moving parts.
The venturi acts as a check valve to keep the collected food soil debris within compartment 80 and to prevent it from flowing out through the outlet 88 during opera-tion in the soil collecting mode, and thus effectively "closes" the debris outlet conduit 88, with no moving parts. On the other hand, if a particularly heavy load of soil is placed within wash chamber 55, and compartment 80 becomes quickly filled, pressure could begin building therein due to partial blockage of the fine mesh screen 90. Such an increase in pressure might extrude some of the food soil debris into and through the openings in the fine mesh screen 90. This would be undesirable since that food soil debris could become lodged in the screen and would be difficult to remove without manual assistance from the machine operator. The venturi advan-tageously operates as a pressure relief valve, however, relieving excess pressure through the debris outlet conduit 88 if the main fluid outlet 90 of the soil collector body 75 becomes obstructed. This limits the pressure within compartment 80 to less than the maximum pressure of which the drain pump ~8 is capable, and effectively prevents serious extruding of the food soil debris through the fine mesh filter screen 90.
Finally, it should be clear that the soil collec-tor operates in the soil collecting mode when wash and rinse fluids are being recirculated within the warewashing ~FN 6555 machine 50, but operates exclusively in the soil discharg-ing mode when diverter valve 78 is switched to drain fluids from the wash chamber 55 through drain line 61.
At that time, no additional food soil debris is collected or removed by the bypass soil collector, so that debris wherever situated within the warewashing machine 50 may be removed therefrom and discharged without hindrance during draining of the wash or rinse fluids. This ~rovides an important advantage over prior art filter systems which operates in series with the primary spray means and continue to capture and entrain food soil debris at the very time it should be released to be flushed down the drain.
Although a typical machine cycle, as shown in Fig. 15, will be described further below, it is worth noting at this point that the optional cycle shown in Fig. 16 is particularly advantageous with a bypass soil collector such as the collector 70 shown in Figs. 1-8.
In that cycle, the bypass soil collector receives a very quick purge to remove any food soil debris which might remain following a normal drain cycle. First, it should be noted that both the drain pump 58 and recirculating pump 57 are normally operated while fluid is being intro-duced into wash chamber 55 during a fill period in the operation of machine 50. Since the drain pump inlet 63 is preferably located at the very bottom of the sump 60, the first fluid introduced into the wash chamber will be circulated through the fluid bypass circuit and lnto the bypass soil collector. Due to the check valve operation of venturi 91, compartment 80 will quickly fill with fluid. If, before sump 60 has begun to fill, machine 50 is then switched to a drain mode of operation, b~ discontinuing the fill and operating diverter valve 78 accordingly, the level of fluid in compartment 80 will be well above that in sump 60, and the fluid will rush out of compartment 80 throuqh the debris outlet

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~ .. .

conduit 88 and directly into the drain pump inlet 63O
This rapid outflowing of the fluid will flush most all of the debris which may remain in compartment 80 ~hrough the drain line 61. It is possible, therefore, to provide 5 the timer for the warewashing machine with a short fill cycle comprising substantially less than the average amount of wash or rinse fluid which is supplied during a normal wash or rinse period. The timer would then operate the recirculating means, that is, drain pump 10 58, to fill compartment 80 with fluid rrom the short fill, ollowing which the drain system would be operated to drain the fluid from the warewashing machine.
Figs~ 9 and 10 illustrate another embodiment 100 of the bypass soil collector which is similar to 15 bypass soil collector 70. However, collector 100 has a fluid inlet conduit 103 which terminates in a pressure operated bellows 105 as it joins the debris outlet conduit 106. As the two conduits 103 and 106 merge, they enter the soil collecting compartment 110 through a common 20 opening 111. The bellows is suitably sized, positioned, and connected, as shown, so that when operated in the soil collecting mode, the pressure of the fluid supplied to bellows 105 by drain pump 58, through the fluid bypass circuit 72, causes it to respond to the pressure of the ~5 fluid and expand across and seal the common opening 111.
Compartment 110 and the fine mesh screen 112 are the separating and connecting means for collector 100, simil-arly as in the preceding embodiment. When the circulating means is operating in the fluid draining mode and the 30 soil collector is therefore operating in the soil discharg-ing mode, as illustrated in Fig. 10, pressure is removed from bellows 105 and it retracts away from opening 111.
This allows the fluid and collected food soil debris in compartment 110 to flow out through the debris outlet ~5 conduit 106 as the fluids are drained from the warewashing machine 50.

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Figs. 11-14 illustrate another bypass soil collector embodiment 130, which is shaped generally like a canister and attached to the bottom of the warewashing machine tank 54 through an opening 132 into the wash chamber 55. Unlike the preceding embodiments, there - is no diverter valve used with the bypass soil collector 130. Instead, it is located directly in the drain line 61 between the drain pump 58 and a drain valve 134.
During a wash or rinse cycle the drain valve 134 is closed, but, as with the previous embodiments, the drain pump 58 remains in operation as long as the recirculating pump 57 and drive motor 59 are operating. This causes fluid to circulate through the fluid bypass circuit into the fluid inlet 135 of the bypass soil collector 130.
The fluid then exits through a fluid outlet 136 at the top of collector 130 where it returns to the wash chamber 55.
A debris outlet 137 connects collector 130 to the drain line through the drain valve 134. The interior of collector 130 is hollow and forms a soil debris collect-ing compartment 138. A filter screen 139 separates compart-ment 138 from the fluid outlet 136. Before the fluid can reach screen 139, it must ascend through an internal extension 142 of fluid inlet 135, and after passing over ~5 ~he walls 143 thereof, the ~luid and food soil debris descend in compartment 138 toward the debris outlet 137.
Screen 139 retains the food soil debris in compartment 138 while permitting the supernatant to return to the wash chamber as indicated above.
As may be seen, the effective cross-sectional flow area of the fluid outlet 136 due to its small diameter, is substantially smaller than that of the internal exten-sion 142 and compar~ment 138, which connect the fluid inlet 135, fluid outiet 136 and debris outlet 137. As a result, the fluid velocity in compartment 138, due to its much larger cross-sectional flow area, is corres-pondingly substantially reduced in comparison with the 33~

velocity in fluid outlet 136. The substantially reduced net velocity of the fluid as it flows through compartment 138 provides an almost static or quiescent zone in the compartment 138 of the soil collector. In the quiescent zone the velocity of the fluid flowing therethrough is so slow that the food soil debris falls and settles to the bottom of the compartment, at the debris outlet 137.
The supernatant which passes through the filter screen 139 then returns to the wash chamber compartment through the fluid outlet 136 which is located well above the bottom of the bypass soil collector 130.
When the soil collector 130 is operated in a soil discharging mode rather than the soil collecting mode, by opening drain valve 134, a large volume high velocity flow of fluid passes through compartment 138 and flushes the collected food soil debris down through the drain line 61. Thus, unlike the preceding embodiments, soil collector 130 is actually located directly in the drain line, and compartment 138 is flushed with the fluids 2Q being drained from the warewashing machine as they are forced to flow into the fluid inlet 135, through compart-ment 138, and out through debris outlet 137. As is also clear from the drawings, the upstream side of the filter 8creen 139 is adjacent the flow path of the fluid as it passes from the fluid inlet to the debris outlet during operation in the soil discharging mode. The movement of the fluid therepast aids in removing debris from the ~ilter screen and flushing it out through the drain line.
Also, by locating the soil collector 130 directly in the drain line itself, the collected food soil debris is forcibly flushed out through the drain line during operation in the soil discharging mode, for affirmatïvely moving the collected food soil debris out of the warewash-ing machine.

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Fig. 15 illustrates a typical wash cycle sequence for a warewashing machine such as machine 50. It is believed that the chart is self-explanatory, showing a Sequence of operations such as ~ill, wash and drain, and no further explanation should be necessary. Fig.
28 shows the first several minutes of the Fig. 15 cycle, to which an optional short purge cycle has been added, as described hereinabove. The balance of the Fig. 16 cycle would be the same as the balance of the Fig. 15 cycle.
As may be seen, therefore, the present invention provides nurnerous advantages. The major benefit is the substantial conservation of water which this invention makes possible. It goes without question that the cleaner the water at the start, the cleaner will be the food ware items at the end. It is therefore important to get the soil off the food ware items and out of the wash chamber as fast as possible. For example, a warewashing machine of the type shown in Fig. 1~ manufactured by the assignee of the present invention and not equipped with the present invention, fills and drains six times and uses approximately 13 1/2 gallons of hot water in a normal wash cycle. When equipped with the bypass soil collector 70 and operated according to the cycle shown ~5 in Fig. 15, equivalent results were obtained with but ~our fills and ~ gallons of hot water, a saving of 41 percent. Recognizing the importance of saving energy and natural resources, it can be seen that the present invention provides substantial and important improvemen~s in the operation of such warewashing machines.
Since the present invention is independent of the primary spray means, much finer filtering may be used to reduce the redeposit problems. For example, filter screen 65 for the recirculating system has openings of 1.2mm diameter, whereas the circulating system f ine mesh filter screen 90 in collector 70 has openings of only 0.8mm diamter. Ordinarily screen 90 does not become blocked, but during extreme soil conditions, if the very small openings in the fine mesh screen 90 should become blocked, this will not impair the operation of the prima~y ~pray means. Further, the debris which is stopped hy screen 90 and held in compartment 80 is isolated fxom the influence of the primary spray means and is therefore not emulsified or disintegrated. Instead, it is quickly flushed out through the drain line as soon as the ware-washing machine wash chamber is emptied, thereby furtherreducing redeposit problems. At the conclusion of the drain period, the ~ash chamber and the bypass soil col-)lector are both drained o~ flu~ds, so that water is notleft standing where bacteria might develop and grow during periods that the warewashing machine is not being used.
In the preferred embodiment, two separa~e pumps are used, although the present invention can also be used in warewashing machines which have but a single pump. Dual pum~ machines provide the additional advantage that the bypass soil collector does not reduce the fluid volume and pressure flowing through the recirculating pump and spray means. Instead, the bypass soil collector relies on the drain pump for circulating the fluids through the fluid bypass circuit. In either case, circu-lation through the fluid bypass circuit is affirmative,in direct response to the action of a pump, and is much more effective than random or splash methods of debris collection. Flow through the fluid bypass circuit is also essentially unrestricted, in the sense that it is not affected or retarded by the high pressure or primary spray arms. Also, the debris which has been collected is readily and quickly disposed of on command when opera-tion is shifted from soil collecting to soil discharging.
While diverter and drain valves 78 and 134 have been used with the foregoing embodiments, the present invention is equally suited for use in warewashing machines having other drainage controls. For example, a valveless drain system having a reversible pump and elevated drain conduit, as shown in U.S. Patent 3,810,480, may be used.
In such a system, a bypass soil collector such as collectors 130 or 150, would be located in the drain line at heights below the standing fluid height in the elevated drain conduit. Then, during a wash or rinse period the reverse rotating drain impeller would create a pressure head sufficient to conduct fluid through the bypass soil col-lector and back to the wash chamber, but not great enoughto pass the fluid out through the drain line. During a drain period the drain pump rotation would be reversed, to turn in its forward direction, thereby developing a much greater pressure and pumping the fluid and debris out through the bypass soil collector and drain line.
Another principal advantage of the present invention is that it is essentially self-cleaning. ~anual intervention or assistance on the part of the machine operator is almost never required. The screen 90 and upwardly open compartment 80 have been located in positions readily accessible to the machine user, in the event that cleaning or servicing should be desired, but such service is virtually never required. The collected debris readily flushes outwardly through the drain line on command.
The disposer g3 at the drain pump inlet virtually eliminates the need for a coarse filter and reduces almost all the large size food soil debris particles to dimensions which will pass through the bypass soil collection circuit and then out through the drain line. The present invention thus provides maximum washability with minimum maintenanceO
The soil collector 70 (as well as several of the other embodiments) includes several additional advan- -tages. Its venturi check valve, which keeps the collected food debris within compartment 80 until the collector is operated in the soil discharging mode, has no moving parts, thus minimizing maintenance and maximizing longevity.
If a cycle is interrupted, the soil collector will retain the food soil debris in the compartment until the proper time for discharging it. The soil collector is also highly tolerant of overload conditions. Upon disposal, the collected food soil debris is flushed out the drain with essentially no contamination of ~he wash chamber itself.
The versatility of the present invention and its many alternative embodiments thus sui~ it for use in the widest variety of warewashing applications and machine and pumping configurations. It is suitable for use in circulating systems having one or more than one pump, whether valved or valveless, with single or plural wash arms or splash impellers, as well as the many other modifications within the scope of the invention which will become apparent on reading the present disclosure.
The construction is neither complicated nor expensive, yet is durable, reliable, and efficient, saving water and energy resources by substantially reducing the con-sumption of both.
While the methods herein described, and theforms of apparatus for carrying them into effect, consti-tute preferred embodiments of this invention, it is to be understood that the invention is not limited thereto, and that changes may be made therein without departing from the scope of the invention.

Claims (7)

CLAIMS:

1. In a dishwasher which utilizes multiple fluid fills for sequentially washing and rinsing food ware items during a complete cycle, said diswasher having a wash chamber including rack means for receiving and supporting food ware items therein and a sump at the bottom of said chamber for containing fluid therein; primary spray means including a wash pump operable in a recirculating mode for recirculating and spraying fluid from said sump onto food ware items to remove food soil particles therefrom and carry food soil particles to the sump; a drain system having a drain inlet adjacent the bottom of said sump, a drain outlet communicating with a drain, and a drain pump operable in a draining mode for pumping fluid and food soil particles therein from said sump to a drain at intervals between successive fluid fills; and soil collector means for continuously collecting and removing food soil particles from fluid in said sump while said primary spray means is operating; the improvement comprising:
a) said soil collector means comprising a soil collecting circuit having an inlet connected to receive fluid from said drain pump, a return outlet located within said wash chamber, and a portion, independent of said primary spray means and said wash chamber, in fluid communication with said inlet and said return outlet;
b) said portion including a relatively fine screen, soil collecting filter in said portion for removing food soil particles from fluid circulating through said soil collecting circuit to be retained with said portion during said recirculating mode, said filter having its upstream side in position to have collected soil particles flushed therefrom toward said drain outlet and into a drain during said draining mode; and c) means for selectively controlling said dishwasher to operate said drain pump in either a soil collecting mode by circulating fluid through said soil collecting circuit while said primary spray means is recirculating and spraying fluid onto food ware items or in a drain mode to simultaneously pump fluid and soil particles from said sump during draining.

HMC 6555 Can. - Claims

2. The dishwasher of claim 1 wherein said drain system includes a drain line communicating with said soil collecting circuit and extending from said drain pump to said drain outlet and said selective control means comprises valve means located in said drain line between said drain outlet and said filter, whereby fluid is caused to circulate through said soil collecting circuit when said valve means is closed and caused to pass through said drain system when said valve means is opened.

3. The dishwasher of claim 2 wherein said outlet of said soil collecting circuit includes a fluid flow restriction and wherein said valve means comprises a drain valve operable between open and closed positions, opening of said drain valve enabling fluid under pressure from said drain pump to follow the path of least resistance through said drain system.

4. The diswasher of claim 2 wherein said drain system is so located with respect to a downstream side of said soil collecting filter that opening of said drain valve causes said drain pump to simultaneously drain fluid and soil and flush said soil collecting filter.

5. The dishwasher of claim 1 including a separate screen filter having a mesh size slightly larger than said soil collecting filter and arranged for filtering food soil particles from fluid entering said wash pump of said primary spray means, the relative mesh size of said soil collecting filter and said separate filter being such that said soil collecting filter traps and collects relatively fine soil particles on their initial pass through said soil collecting circuit, and soil particles passing through said separate filter and thereby being recirculated onto ware being soil particles which have not been entrained in said soil collecting circuit and which are also of a slightly larger particle size capable of passing through said separate filter.

HMC 6555 Can. - Claims

6. The combination of claim 1, 2, or 3, further comprising means forming a compartment in said soil collecting filter in which food soil particles are collected and held, said compartment communicating with said drain system such that it is flushed with at least a portion of fluid from within said wash chamber as collected food soil particles are being discharged from said compartment into said drain system to assist in flushing food soil particles out through said drain system.

7. The combination of claim 4 or 5, further comprising means forming a compartment in said soil collecting filter in which food soil particles are collected and held, said compartment communicating with said drain system such that it is flushed with at least a portion of fluid from within said wash chamber as collected food soil particles are being discharged from said compartment into said drain system to assist in flushing food soil particles out through said drain system.