CA1115624A - Dishwasher having improved self-cleaning bypass filter - Google Patents
Dishwasher having improved self-cleaning bypass filterInfo
- Publication number
- CA1115624A CA1115624A CA314,822A CA314822A CA1115624A CA 1115624 A CA1115624 A CA 1115624A CA 314822 A CA314822 A CA 314822A CA 1115624 A CA1115624 A CA 1115624A
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- Prior art keywords
- soil
- washing liquid
- filter
- spray
- liquid
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
An automatic dishwashing machine is provided with a bypass soil-collector and filter disposed independent of the sump whereby food soil suspended in the recirculated washing liquid are filtered and collected in a receptacle during the washing/rinsing operation. It includes filter cleaning means as part of the rotation spray arm whereby pressurized washing liquid is directed from the rotation spray arm at the filter screen as the spray arm rotates thereover to backflush soil particles therefrom to prevent clogging. The soil particles fall back into the soil-collector to which the drain is connected so as to remove the washing liquid and the filtered food soil from the receptacle during the drain cycle.
An automatic dishwashing machine is provided with a bypass soil-collector and filter disposed independent of the sump whereby food soil suspended in the recirculated washing liquid are filtered and collected in a receptacle during the washing/rinsing operation. It includes filter cleaning means as part of the rotation spray arm whereby pressurized washing liquid is directed from the rotation spray arm at the filter screen as the spray arm rotates thereover to backflush soil particles therefrom to prevent clogging. The soil particles fall back into the soil-collector to which the drain is connected so as to remove the washing liquid and the filtered food soil from the receptacle during the drain cycle.
Description
11156Z4 9D-D~1-1051~
BACKGROUND OF THE INVENTION
The domestic automatic dishwasher ;s generally of the type having a washing chamber with open-framework racks therein for holding dishes to be washed and means for recirculating washing liquid accumu-lated in the lower end of the washing chamber upwardly over the dishes to loosen and carry away food soil therefrom. An inherent problem in such a machine is that food soil particles are suspended in the recir-culating flow of washing liquid and that redeposition of these par-ticles on the clean dishes can occur during the cleaning process.
During the recirculation of the washing liquid large food particles flushed from the dishes will be carried downwardly and broken up into particularly small particles that are then washed back on to the dishes. These small particles adhere to the cleaned items and often defy removal during subsequent rinsing steps in the operation of the machine.
An approach to correcting this problem has been to provide a means to remove food particles from the recirculating flow so that the washing liquid moving downwardly in the washing chamber carries food soil with it but the same washing liquid redistributed upwardly in the washing chamber is relatively free of these soii particles.
To accomplish this a filtering medium in the form of a screen has been interposed in the path af the liquid recirculation whereby soil particles are prevented from further passage while washing liquid is free to move therethrough and be recirculated in the machine's washing chamber. The use of a filtering screen introduces its own problem;
that of the need for cleaning the collected soil from the screen either between each use of the dishwasher or between wash and rinse steps of the operational cycle so that the screen does not become clogged and thereafter prevent passage of liquid therethrough.
, ~1~56Z4 9D-DW-1051 6 One approach to the filter-cleaning problem has been to provide a removable filter that the machine operator can take out of the machine, rinse in the sink, and then reinstall in the machine for further use. Another and more popular approach has been the provision of a self-cleaning filter wherein the filter is flushed by a reversed flow or an automatic filter rinsing step provided in the operational cycle of the machine. A-notable example of a dish-washing machine having a self-cleaning filtering arrangement is disc,losed in U.S. P'atent No. 2,629,391 issued to F.S. Hummel on February 24, 1953. Hummel teaches the provision of a filtering screen disposed over the sump in the bottom of a dishwashing machine's wash chamber. He also teaches the, use of a specific liquid in-jection step to flush soil from the filter and also to wash collected soil from the sump and outwardly through a gravity drain line.
More recent examples of self-cleaning filter arrangements in dishwashers will be found ih U.S. Patent No. 3,090,391 issued to H.J. Kaldenberg' et al on May 21, 1963 and U.S. Patent No. 3,575,185 issued to D.J. Barbulesco on April 20, 1971. The Kaldenberg et al and Barbulesco patents relate to dishwashing machines utilizing an-annular sump arrangement provided circumjacent the axial flow pumping mechanism in a dishwasher and having an annular screen filter arrange-ment disposed in close proximity to the sump. Each of these patents teaches a different structure for a means for slinging liquid out-wardly toward the annular filter whereby a backwash is accomplished to remove soil particles therefrom.
Commonly assigned U.S. Patent No. 3,807,419, issued to the i, inventors hereof and dated April 30, 1974, teaches the combinati¢n of a self-cleaning filter arrangement with a soil receptacle disposed at a position remote from the wash chamber's sump. Drainage means specifically provide for draining particles from the receptacle during the 11~56Z4 Y~-UW- I u~
drain cycle. This type of filtering system is referred to as a "bypass"
or "partial flow" system since only a portion of the washing liquid is filtered at any given time. At present washing volumes and pump rates, the total volume of liquid is recirculated through the spraying system approximately 20 times per minute. Therefore, it is reasonable to conclude that all of the liquid e'ventually passes through the "bypass"
filter. ûf course, one of the primary advantages of this system, in addition to not requiring manual filter cleansing, is that the dish-washer will continue to operate even if the filter becomes completely clogged. The filter is cleaned or backflushed by the downwardly cas-cading washing liquid which impinges against the downstream-side of the filter screen. It has been fbund that reliance on the downwardly cascading liquid to clean the filter has not been entirely satisfactory and that a more positive self-cleaning arrangement would be more preferable.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an auxiliary filter cleaning spray means for use with a bypass filtering system which preferably takes advantage of existing structure within the machine.
The present invention may be broadly summarized as relating to an automatic dishwashing machine of the type having a washing chamber and means therewith for providing washing liquid in the wash-ing chamber and accumulating it at a relatively low level therein.
~he washing machine includes a spray a~m for circulating the flow of washing liquid generally throughout the washing chamber, and a drainage sump is provided in the bottom wall of the chamber for supplying liquid to the spray arm and for conducting soil-laden washing liquid or effluent out of the machine. A soil-collecting receptacle or trough is provided in the wash chamber having an open portion disposed above the normal level of accumulated liquid in the chamber and in the path of a portion of the liquid recirculated within the chamber. Adjacent the soil-:' ' ' ' '' ' '' ;
ll~S6Z4 collecting receptacle is a fine-mesh screen filter disposed across the flow of liquid recirculation and adapted to pass liquid therethrough while blocking the passage of food soil particles. The filtering screen is situated so that its "collecting" side is disposed toward the aforementioned collecting receptacle. The other side of the screen filter is sprayed with pressurized washing liquid ejecting from a spray-jet formed in the spray arm whereby the soil particles collected on its upstream side are flushed into the collecting receptacle. Means for draining the collected particles from the receptacle is also provided.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l is a side elevational cut-away view of the bottom portion of a domestic dishwashing machine in accordance with the present invention.
Figure 2 is a fragmentary sectional view of a spray arm according to the present invention.
Figure 3 is a fragmentary plan view taken along lines 3-3 of Figure l, and having a cut-away view of the terminal end of the spray arm.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In Flgure l there is illustrated the lower portion of an automat~c dishwashing machine lO including a cabinet ll defining therein a washing chamber 12. Access to the washing chamber 12 is obta1ned by opening a door 13 pivoted at its lower end and located on the front side of the cabinet ll. A dish rack 14 is shown supported for slidable movement within the washing chamber 12 so that it may be selectively slid outwardly through the cabinet's front ~^
access open1ng to facilitate loading and unloading of the items to be washed in the machine lO. The lower end of the washing`chamber 12 1s defined by a bottom wall or floor portion 15 that separates it from a,lower motor-pump compartment 16. Housed within the compartment ` 11~L5624 9D-DW-10516 16 is a motor-pump assembly 17 including an electric motor 18 that drives a pump means 19 for recirculating washing liquid to and from the washing chamber 12 and for draining washing liquid from the washing -chamber 12 outwardly to the household sewage system. The operational cycle of such a machine generally includes a number of washing and rinsing steps and a final drying step. In a dishwasher machine, such as that shown in Figure 1, heated water from the household supply line is directed into the washing chamber 12 by valve means actuated by a timer control ~not shown). The water accumulates to a predetermined level on the floor portion 15 and then the timer control of the mdchine causes the electric motor 18 to be energized to drive the pump 19 in a recirculation operation. This method of fill is called the "static" method. A dynamic fill is also used whereby the motor is energized ant the pump goes into the recirculation mode during a time-controlled fill period. In the recirculation operation the accumulated washing liquid is drained out of the washing chamber 12 by means of a sump 20 emptying into a conduit 21 leading to the pump 19. The liquid is then forced upwardly by the pump 19 through a conduit 22 leading to a hollow horizontally elongated spray arm 25 located within the !ower portion of the washing chamber 12.
Generally, clean water is introduced into the machine for each wash step and again for each rinse step, and detergent is added, by automatic means (not shown), for the wash step. The term "washing liquid" is therefore used herein in a generic sense to refer broadly to any fonm of cleansing liquid utilized for recirculation within the dishwashing machine. The washing liquid is distributed from the spray arm 25 by means of orifices 26 spaced therealong. The spray arm 25 is reactively driven by having at least one of the orifices disposed to discharge a jet stream in a direction such that the spray arm reacts to the force of the discharge and rotates in a horizontal plane. A
1~156~ 9D-DW-10516 thorough and generally uniform distribution of washing liquid in the wash1ng chamber 12 is thereby obtained. Recirculation of the washing liquid from the washing chamber 12, through the pump 19 and, thence through the spray arm 25, is continued for a predetermined length of ` time after which the electrical circuit to a drain valve means (not shown) causes the valve to automatically switch an outlet within the pump means 19 so that recirculation ceases and the pump 19 begins to discharge the washing liqu1d from the washing chamber 12 outwardly through a drain hose 27 leading ultimately to the household sewage system.
Shown in Figure 1 and more specifically in Figure 3, is a so11-removal means 82 in the form of a receptacle 30 having a trough 31 d1sposed 1n the path of recirculation of liquid within the washing chamber 12 and adapted to fill and overflow with the recirculated 11quid caught therein. The so11-removal means further includes the f11ter~ng means 32 contiguous to the trough 31 and disposed in the path of the 11qu1d flow whereby liquid from the receptacle passes through the screen wh11e soil particles carried in the washing liquid are blocked from passage and therefore halt against the back or up-stream side of the screen. As shown in Figure 3, the trough 31 may be transversely elongated to extend across the substantially entire back wall 34 of chamber 12. In addition to the trough 31, the receptacle 30 further comprises a lower end portion in the form of a tubular box or hopper 35. The trough 31 has a configuration such that liquid and soil part1cles collected therein will flow centrally downwardly through an opening (not shown) into the hopper 35. A bottom 33a of the trough 31 1s sloped centrally downwardly, and a back wall portion 33b, as shown in Figure 1, is sloped inwardly whereby motion of the liquid collected 1n the trough will cause soil particles to flow toward the central bottom open~ng. The side of the trough 31 facing toward the wash . . . _ . , .
1~56Z4 9D DW 10516 chamber 12 has an erect wall portion 33c that extends upwardly to the lower edge of the filtering screen 32. It should be noted that wall 33c of trough 31 is at least partially above the normal level of washing liquid accumulated on the bottom 15 of chamber 12. The filtering screen 32 is disposed at approximately a 45 angle with reference to the back wall 34 of the wash chamber 12, and the upper long edge of the filtering screen 32 abuts against the forward edge of a horizontally disposed perforated cover plate 37. The cover plate 37 is disposed across the trough's opening and is provided with a uniform arrangement of apertures 38 equidistantly spaced thereacross, as shown in Figure 3. Successive longitudin-ally oriented slots 39 are also provided in the cover plate 37.
The cover plate 37 may be said to partially enclose a first open top means 88 of receptacle 30 serving to collect recirculating liquid falling therein. Cover plate 37 also forms a second open top means 89 of receptacle 30 wherein the filter 32 is secured as described above.
For more detailed illustration and description of the soil-removing means 82 reference may be made to the above-mentioned com~only-assigned U.S. Patent No. 3,807,419, and specifically Figures 2-4 thereof.
Referring more specifically to Figures 2 and 3, the filter cleaning means 70 is shown. Figure 2 illustrates one of the terminal ends of spray arm 25, having an orifice 80 formed therein. One skilled in the art will appreciate that the orifice or spray-jet 80 could take on several configurations, e.g., a protruding nozzle, and could serve to reactively drive the spray arm 25 as described above. As the spray arm 25 rotates thereby periodically traversing or passing over the filter means 32 r shown better in Figure 3, it can be seen that the pressur-ized liquid is directed generally radially outwardly and downwardly against the filter means 32. Although spray-jet 80 is shown adjacent the terminal end of spray arm 25 and in rather close proximity to soil-removing means 82 (see Figure 1), the exact location may be varied to accommodate the various internal structural embodiments of such dishwashers without departing from the scope and intent of the invention. The direct force of the liquid spray from the jet 80 impinging against the outside or downstream surface of filter 32 serves to jar soi~ loose from the upstream or back side of the filter 32 whereby it will continually move away from the filter as it collects thereagainst to keep the filter open for passage of washing liquid therethrough. .
In the operation of the dishwasher 10 shown in Figure 1, the washing step of the operational cycle commences with the intro-duction of water to the washing chamber 12 whereby water accumulates on the floor portion 15 to a maximum level below the under surface of the spray arm 25 and below the bottom-most portion of screen 32.
Detergent is automatically added to the water and the resultant washing liquid is caused to follow a circular path down the sump 20 and through the conduit 21 to the pump 19. As heretofore described, motor 18 causes the pump 19 to force the washing liquid upwardly and outwardly through the hollow spray arm 25. The spray arm 25 rotates in response to a ~et stream discharged from at least one end thereof and the orifices 26 discharge strezms of washing liquid upwardly over items stored in the rack 14 and generally over additional items in one or more other vertically spaced racks (not shown). The cascade of wash-ing.liquid distributed through the washing chamber 12 tends to progress downwardly over the items in the rzck but primarily down along the inside surface of the door 13, the side walls of the wash chamber 12 and the back wall 34. Therefore, the back wall 34 serves as a shedding ~ . . . . ... .: . .
. . .
surface for directing recirculated washing liquid downwardly against the cover plate 37.
As the washing step (or rinsing step) progresses for its predetermined time, the soil-laden washing liquid flows downwardly repeatedly along the washing chamber back wall 34 toward the cover plate 37. Much of the washing liquid moves through the slots 39 and the perforations 38 of the cover plate 37 and into the trough 31.
Obviously, once the trough 31 is initially filled, it flows over its forward wall 33c and outwardly through the filtering screen 32. The filtering screen 32 is preferably of a fine mesh whereby even very smal1 food soil particles will be blocked.from passage therethrough and retained by the back side of the filtering screen 32. The filtering screen 32 is disposed whereby washing liquid moving down behind the rack 14 and forward of the back wall 34 will strike against the outside surface of the screen. The force of the downwardly cas-cading washing liquid and the pressurized spray from jet 80 as described above, impinges against the outside surface of the screen 32 serving to jar soil loose from the back side of the screen 32 whereby it will continuously move away from the screen as it collects thereagainst to keep the screen open for passage of washing liquid therethrough. As quantities of soil particles retained in the trough 31 by the screen 32 increase and agglomerate, they tend to precipitate and settle downwardly into the tubular hopper 35 so that by the end of the wash step of the machine's operational cycle a high percentage of suspended soil particles have thus been removed from the recirculated washing liquid in the wash chamber 12 and collected in the hopper 35. At the end of the washing step, the timer-control means (not shown) energizes the drain valve means for a period to permit final drainage of liquld from the cleaned items in the chamber 12. After the drain valve is automatically moved from the first to 1~5624 9D-DW-10516 the second position, the pump 19 continues to receive the washing liquid from the chamber 12 through the sump 20 and the conduit 21 and will pump it outwardly through the drain line 27 to the lower end of the hopper 35. The drainage flow or effluent is pumped through the hopper and outwardly through a final discharge line 44 draining out-wardly from the dishwasher 10. The final discharge line 44 on a permanently installed dishwasher would lead directly to the household sewage system. On a portable type of dishwashing machine the final discharge line 44 would be provided with an outer end disposed to dispense the effluent liquid into the kitchen sink.
In order to accomplish effective drainage of hopper 35 various mechanisms may be employed. Two such devices are shown and described in the above-mentioned commonly-assigned U.S. Patent No.
3,807,419, and specifically Figures 4 and 5 thereof.
It should be apparent to those skilled in the art that the embodiments described heretofore are considered to be the presently preferred fonms of this invention. In accordance with the Patent - Statutes, changes may be made in the disclosed mechanism in the manner in which it is used without actually departing from the true spirit and scope of this ~nvention. For example, a cleaning jet could be located at the ~b (22) below the spray anm, or positioned in a vertical extension from the top of the spray arm 25 (as is known in the art) and be directed at the filter 32 thereby cleaning the filter as the spray arm revolutes.
BACKGROUND OF THE INVENTION
The domestic automatic dishwasher ;s generally of the type having a washing chamber with open-framework racks therein for holding dishes to be washed and means for recirculating washing liquid accumu-lated in the lower end of the washing chamber upwardly over the dishes to loosen and carry away food soil therefrom. An inherent problem in such a machine is that food soil particles are suspended in the recir-culating flow of washing liquid and that redeposition of these par-ticles on the clean dishes can occur during the cleaning process.
During the recirculation of the washing liquid large food particles flushed from the dishes will be carried downwardly and broken up into particularly small particles that are then washed back on to the dishes. These small particles adhere to the cleaned items and often defy removal during subsequent rinsing steps in the operation of the machine.
An approach to correcting this problem has been to provide a means to remove food particles from the recirculating flow so that the washing liquid moving downwardly in the washing chamber carries food soil with it but the same washing liquid redistributed upwardly in the washing chamber is relatively free of these soii particles.
To accomplish this a filtering medium in the form of a screen has been interposed in the path af the liquid recirculation whereby soil particles are prevented from further passage while washing liquid is free to move therethrough and be recirculated in the machine's washing chamber. The use of a filtering screen introduces its own problem;
that of the need for cleaning the collected soil from the screen either between each use of the dishwasher or between wash and rinse steps of the operational cycle so that the screen does not become clogged and thereafter prevent passage of liquid therethrough.
, ~1~56Z4 9D-DW-1051 6 One approach to the filter-cleaning problem has been to provide a removable filter that the machine operator can take out of the machine, rinse in the sink, and then reinstall in the machine for further use. Another and more popular approach has been the provision of a self-cleaning filter wherein the filter is flushed by a reversed flow or an automatic filter rinsing step provided in the operational cycle of the machine. A-notable example of a dish-washing machine having a self-cleaning filtering arrangement is disc,losed in U.S. P'atent No. 2,629,391 issued to F.S. Hummel on February 24, 1953. Hummel teaches the provision of a filtering screen disposed over the sump in the bottom of a dishwashing machine's wash chamber. He also teaches the, use of a specific liquid in-jection step to flush soil from the filter and also to wash collected soil from the sump and outwardly through a gravity drain line.
More recent examples of self-cleaning filter arrangements in dishwashers will be found ih U.S. Patent No. 3,090,391 issued to H.J. Kaldenberg' et al on May 21, 1963 and U.S. Patent No. 3,575,185 issued to D.J. Barbulesco on April 20, 1971. The Kaldenberg et al and Barbulesco patents relate to dishwashing machines utilizing an-annular sump arrangement provided circumjacent the axial flow pumping mechanism in a dishwasher and having an annular screen filter arrange-ment disposed in close proximity to the sump. Each of these patents teaches a different structure for a means for slinging liquid out-wardly toward the annular filter whereby a backwash is accomplished to remove soil particles therefrom.
Commonly assigned U.S. Patent No. 3,807,419, issued to the i, inventors hereof and dated April 30, 1974, teaches the combinati¢n of a self-cleaning filter arrangement with a soil receptacle disposed at a position remote from the wash chamber's sump. Drainage means specifically provide for draining particles from the receptacle during the 11~56Z4 Y~-UW- I u~
drain cycle. This type of filtering system is referred to as a "bypass"
or "partial flow" system since only a portion of the washing liquid is filtered at any given time. At present washing volumes and pump rates, the total volume of liquid is recirculated through the spraying system approximately 20 times per minute. Therefore, it is reasonable to conclude that all of the liquid e'ventually passes through the "bypass"
filter. ûf course, one of the primary advantages of this system, in addition to not requiring manual filter cleansing, is that the dish-washer will continue to operate even if the filter becomes completely clogged. The filter is cleaned or backflushed by the downwardly cas-cading washing liquid which impinges against the downstream-side of the filter screen. It has been fbund that reliance on the downwardly cascading liquid to clean the filter has not been entirely satisfactory and that a more positive self-cleaning arrangement would be more preferable.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide an auxiliary filter cleaning spray means for use with a bypass filtering system which preferably takes advantage of existing structure within the machine.
The present invention may be broadly summarized as relating to an automatic dishwashing machine of the type having a washing chamber and means therewith for providing washing liquid in the wash-ing chamber and accumulating it at a relatively low level therein.
~he washing machine includes a spray a~m for circulating the flow of washing liquid generally throughout the washing chamber, and a drainage sump is provided in the bottom wall of the chamber for supplying liquid to the spray arm and for conducting soil-laden washing liquid or effluent out of the machine. A soil-collecting receptacle or trough is provided in the wash chamber having an open portion disposed above the normal level of accumulated liquid in the chamber and in the path of a portion of the liquid recirculated within the chamber. Adjacent the soil-:' ' ' ' '' ' '' ;
ll~S6Z4 collecting receptacle is a fine-mesh screen filter disposed across the flow of liquid recirculation and adapted to pass liquid therethrough while blocking the passage of food soil particles. The filtering screen is situated so that its "collecting" side is disposed toward the aforementioned collecting receptacle. The other side of the screen filter is sprayed with pressurized washing liquid ejecting from a spray-jet formed in the spray arm whereby the soil particles collected on its upstream side are flushed into the collecting receptacle. Means for draining the collected particles from the receptacle is also provided.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure l is a side elevational cut-away view of the bottom portion of a domestic dishwashing machine in accordance with the present invention.
Figure 2 is a fragmentary sectional view of a spray arm according to the present invention.
Figure 3 is a fragmentary plan view taken along lines 3-3 of Figure l, and having a cut-away view of the terminal end of the spray arm.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
In Flgure l there is illustrated the lower portion of an automat~c dishwashing machine lO including a cabinet ll defining therein a washing chamber 12. Access to the washing chamber 12 is obta1ned by opening a door 13 pivoted at its lower end and located on the front side of the cabinet ll. A dish rack 14 is shown supported for slidable movement within the washing chamber 12 so that it may be selectively slid outwardly through the cabinet's front ~^
access open1ng to facilitate loading and unloading of the items to be washed in the machine lO. The lower end of the washing`chamber 12 1s defined by a bottom wall or floor portion 15 that separates it from a,lower motor-pump compartment 16. Housed within the compartment ` 11~L5624 9D-DW-10516 16 is a motor-pump assembly 17 including an electric motor 18 that drives a pump means 19 for recirculating washing liquid to and from the washing chamber 12 and for draining washing liquid from the washing -chamber 12 outwardly to the household sewage system. The operational cycle of such a machine generally includes a number of washing and rinsing steps and a final drying step. In a dishwasher machine, such as that shown in Figure 1, heated water from the household supply line is directed into the washing chamber 12 by valve means actuated by a timer control ~not shown). The water accumulates to a predetermined level on the floor portion 15 and then the timer control of the mdchine causes the electric motor 18 to be energized to drive the pump 19 in a recirculation operation. This method of fill is called the "static" method. A dynamic fill is also used whereby the motor is energized ant the pump goes into the recirculation mode during a time-controlled fill period. In the recirculation operation the accumulated washing liquid is drained out of the washing chamber 12 by means of a sump 20 emptying into a conduit 21 leading to the pump 19. The liquid is then forced upwardly by the pump 19 through a conduit 22 leading to a hollow horizontally elongated spray arm 25 located within the !ower portion of the washing chamber 12.
Generally, clean water is introduced into the machine for each wash step and again for each rinse step, and detergent is added, by automatic means (not shown), for the wash step. The term "washing liquid" is therefore used herein in a generic sense to refer broadly to any fonm of cleansing liquid utilized for recirculation within the dishwashing machine. The washing liquid is distributed from the spray arm 25 by means of orifices 26 spaced therealong. The spray arm 25 is reactively driven by having at least one of the orifices disposed to discharge a jet stream in a direction such that the spray arm reacts to the force of the discharge and rotates in a horizontal plane. A
1~156~ 9D-DW-10516 thorough and generally uniform distribution of washing liquid in the wash1ng chamber 12 is thereby obtained. Recirculation of the washing liquid from the washing chamber 12, through the pump 19 and, thence through the spray arm 25, is continued for a predetermined length of ` time after which the electrical circuit to a drain valve means (not shown) causes the valve to automatically switch an outlet within the pump means 19 so that recirculation ceases and the pump 19 begins to discharge the washing liqu1d from the washing chamber 12 outwardly through a drain hose 27 leading ultimately to the household sewage system.
Shown in Figure 1 and more specifically in Figure 3, is a so11-removal means 82 in the form of a receptacle 30 having a trough 31 d1sposed 1n the path of recirculation of liquid within the washing chamber 12 and adapted to fill and overflow with the recirculated 11quid caught therein. The so11-removal means further includes the f11ter~ng means 32 contiguous to the trough 31 and disposed in the path of the 11qu1d flow whereby liquid from the receptacle passes through the screen wh11e soil particles carried in the washing liquid are blocked from passage and therefore halt against the back or up-stream side of the screen. As shown in Figure 3, the trough 31 may be transversely elongated to extend across the substantially entire back wall 34 of chamber 12. In addition to the trough 31, the receptacle 30 further comprises a lower end portion in the form of a tubular box or hopper 35. The trough 31 has a configuration such that liquid and soil part1cles collected therein will flow centrally downwardly through an opening (not shown) into the hopper 35. A bottom 33a of the trough 31 1s sloped centrally downwardly, and a back wall portion 33b, as shown in Figure 1, is sloped inwardly whereby motion of the liquid collected 1n the trough will cause soil particles to flow toward the central bottom open~ng. The side of the trough 31 facing toward the wash . . . _ . , .
1~56Z4 9D DW 10516 chamber 12 has an erect wall portion 33c that extends upwardly to the lower edge of the filtering screen 32. It should be noted that wall 33c of trough 31 is at least partially above the normal level of washing liquid accumulated on the bottom 15 of chamber 12. The filtering screen 32 is disposed at approximately a 45 angle with reference to the back wall 34 of the wash chamber 12, and the upper long edge of the filtering screen 32 abuts against the forward edge of a horizontally disposed perforated cover plate 37. The cover plate 37 is disposed across the trough's opening and is provided with a uniform arrangement of apertures 38 equidistantly spaced thereacross, as shown in Figure 3. Successive longitudin-ally oriented slots 39 are also provided in the cover plate 37.
The cover plate 37 may be said to partially enclose a first open top means 88 of receptacle 30 serving to collect recirculating liquid falling therein. Cover plate 37 also forms a second open top means 89 of receptacle 30 wherein the filter 32 is secured as described above.
For more detailed illustration and description of the soil-removing means 82 reference may be made to the above-mentioned com~only-assigned U.S. Patent No. 3,807,419, and specifically Figures 2-4 thereof.
Referring more specifically to Figures 2 and 3, the filter cleaning means 70 is shown. Figure 2 illustrates one of the terminal ends of spray arm 25, having an orifice 80 formed therein. One skilled in the art will appreciate that the orifice or spray-jet 80 could take on several configurations, e.g., a protruding nozzle, and could serve to reactively drive the spray arm 25 as described above. As the spray arm 25 rotates thereby periodically traversing or passing over the filter means 32 r shown better in Figure 3, it can be seen that the pressur-ized liquid is directed generally radially outwardly and downwardly against the filter means 32. Although spray-jet 80 is shown adjacent the terminal end of spray arm 25 and in rather close proximity to soil-removing means 82 (see Figure 1), the exact location may be varied to accommodate the various internal structural embodiments of such dishwashers without departing from the scope and intent of the invention. The direct force of the liquid spray from the jet 80 impinging against the outside or downstream surface of filter 32 serves to jar soi~ loose from the upstream or back side of the filter 32 whereby it will continually move away from the filter as it collects thereagainst to keep the filter open for passage of washing liquid therethrough. .
In the operation of the dishwasher 10 shown in Figure 1, the washing step of the operational cycle commences with the intro-duction of water to the washing chamber 12 whereby water accumulates on the floor portion 15 to a maximum level below the under surface of the spray arm 25 and below the bottom-most portion of screen 32.
Detergent is automatically added to the water and the resultant washing liquid is caused to follow a circular path down the sump 20 and through the conduit 21 to the pump 19. As heretofore described, motor 18 causes the pump 19 to force the washing liquid upwardly and outwardly through the hollow spray arm 25. The spray arm 25 rotates in response to a ~et stream discharged from at least one end thereof and the orifices 26 discharge strezms of washing liquid upwardly over items stored in the rack 14 and generally over additional items in one or more other vertically spaced racks (not shown). The cascade of wash-ing.liquid distributed through the washing chamber 12 tends to progress downwardly over the items in the rzck but primarily down along the inside surface of the door 13, the side walls of the wash chamber 12 and the back wall 34. Therefore, the back wall 34 serves as a shedding ~ . . . . ... .: . .
. . .
surface for directing recirculated washing liquid downwardly against the cover plate 37.
As the washing step (or rinsing step) progresses for its predetermined time, the soil-laden washing liquid flows downwardly repeatedly along the washing chamber back wall 34 toward the cover plate 37. Much of the washing liquid moves through the slots 39 and the perforations 38 of the cover plate 37 and into the trough 31.
Obviously, once the trough 31 is initially filled, it flows over its forward wall 33c and outwardly through the filtering screen 32. The filtering screen 32 is preferably of a fine mesh whereby even very smal1 food soil particles will be blocked.from passage therethrough and retained by the back side of the filtering screen 32. The filtering screen 32 is disposed whereby washing liquid moving down behind the rack 14 and forward of the back wall 34 will strike against the outside surface of the screen. The force of the downwardly cas-cading washing liquid and the pressurized spray from jet 80 as described above, impinges against the outside surface of the screen 32 serving to jar soil loose from the back side of the screen 32 whereby it will continuously move away from the screen as it collects thereagainst to keep the screen open for passage of washing liquid therethrough. As quantities of soil particles retained in the trough 31 by the screen 32 increase and agglomerate, they tend to precipitate and settle downwardly into the tubular hopper 35 so that by the end of the wash step of the machine's operational cycle a high percentage of suspended soil particles have thus been removed from the recirculated washing liquid in the wash chamber 12 and collected in the hopper 35. At the end of the washing step, the timer-control means (not shown) energizes the drain valve means for a period to permit final drainage of liquld from the cleaned items in the chamber 12. After the drain valve is automatically moved from the first to 1~5624 9D-DW-10516 the second position, the pump 19 continues to receive the washing liquid from the chamber 12 through the sump 20 and the conduit 21 and will pump it outwardly through the drain line 27 to the lower end of the hopper 35. The drainage flow or effluent is pumped through the hopper and outwardly through a final discharge line 44 draining out-wardly from the dishwasher 10. The final discharge line 44 on a permanently installed dishwasher would lead directly to the household sewage system. On a portable type of dishwashing machine the final discharge line 44 would be provided with an outer end disposed to dispense the effluent liquid into the kitchen sink.
In order to accomplish effective drainage of hopper 35 various mechanisms may be employed. Two such devices are shown and described in the above-mentioned commonly-assigned U.S. Patent No.
3,807,419, and specifically Figures 4 and 5 thereof.
It should be apparent to those skilled in the art that the embodiments described heretofore are considered to be the presently preferred fonms of this invention. In accordance with the Patent - Statutes, changes may be made in the disclosed mechanism in the manner in which it is used without actually departing from the true spirit and scope of this ~nvention. For example, a cleaning jet could be located at the ~b (22) below the spray anm, or positioned in a vertical extension from the top of the spray arm 25 (as is known in the art) and be directed at the filter 32 thereby cleaning the filter as the spray arm revolutes.
Claims (11)
1. In combination with an automatic dishwashing machine having a wash chamber, means for accumulating washing liquid in the lower portion of the chamber and circulating the washing liquid throughout the chamber, soil-removal means independent of the accumu-lating means and disposed in the path of a portion of the recirculated liquid for filtering and collecting soil particles, the soil-removal means including means for effecting drainage thereof at a predetermined time during operation of the machine, the improvement comprising:
means for directing pressurized washing liquid at said soil-removal means in a direction opposite to that of the normal path of recirculation.
means for directing pressurized washing liquid at said soil-removal means in a direction opposite to that of the normal path of recirculation.
2. The combination of Claim 1 wherein the means for accumulating and circulating washing liquid includes rotatable spray means adaptable to periodically traverse said soil-removal means.
3. The combination of Claim 2 wherein the means for directing washing liquid at said soil-removal means comprises spray-jet means formed in said rotatable spray means.
4. The combination of Claim 2 wherein said rotatable spray means comprises an elongated spray arm having a plurality of washing jets formed to spray dishes stacked in said machine.
5. The combination of Claim 4 wherein the means for dir-ecting washing liquid at said soil-removal means comprises at least one spray jet formed in said spray arm, said jet disposed so as to direct pressurized washing liquid at substantially the entire filtering surface of said soil-removal means as said rotating spray arm traverses said soil-removal means.
6. The combination of Claim 5 wherein said spray jet is formed adjacent the terminal end of said spray arm.
7. In an automatic dishwashing machine of the type having a housing enclosing an interior space wherein dishes are placed, pump means in the bottom of the housing including a sump wherein wash-ing liquid is collected for recirculation, means for recirculating washing liquid in communication with the pump means, soil-removing means independent of the sump and having filter means disposed at least partially above the normal level of accumulated liquid, the filter means being in the path of a portion of washing liquid being recirculated and having a soil-collecting up-stream side and a down-stream side, means for draining the soil-removing means and the sump outwardly from the machine, and filter cleaning means in liquid flow communication with said recirculating means, said cleaning means adap-ted to direct pressurized washing liquid against said downstream side of said filter means thereby dislodging soil particles therefrom.
8. The combination of Claim 7 wherein the recirculating means comprises a rotatable elongated spray arm having a plurality of spray jets therein generally directed upwardly toward the dishes placed in the machine, and disposed so as to periodically traverse said filter means in close proximity to its downstream side.
9. The combination of Claim 8 wherein the filter cleaning means comprises jet means formed in said spray arm, said jet means disposed so that washing liquid is sprayed generally radially down-wardly against said filter means.
10. The invention of Claim 7 wherein the soil-removing means comprises a receptacle having drainage means disposed at the bottom thereof, and first and second generally open top means, said first top means adapted to collect a portion of the liquid being recir-culated by said recirculating means, and said second top means adapted to receive said filter means therein and pass the fluid collected in said receptacle to the interior of the machine for collection in the sump.
11. The invention of Claim 10 wherein the filter means comprises a fine-mesh screen having said soil-collecting side facing interior of said receptacle and said downstream side facing said cleaning means.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US86131677A | 1977-12-16 | 1977-12-16 | |
| US861,316 | 1977-12-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1115624A true CA1115624A (en) | 1982-01-05 |
Family
ID=25335477
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA314,822A Expired CA1115624A (en) | 1977-12-16 | 1978-10-30 | Dishwasher having improved self-cleaning bypass filter |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1115624A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108498046A (en) * | 2017-02-27 | 2018-09-07 | 伊莱克斯商用电器有限公司 | Wash the dishes machine |
-
1978
- 1978-10-30 CA CA314,822A patent/CA1115624A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108498046A (en) * | 2017-02-27 | 2018-09-07 | 伊莱克斯商用电器有限公司 | Wash the dishes machine |
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