Patent Application
20140202502
The subject matter of the present disclosure relates generally to filtration of the wash and/or rinse fluids in a dishwashing appliance.
During wash and rinse cycles, dishwashers typically circulate a fluid through a wash chamber over articles such as pots, pans, silverware, and other cooking utensils. The fluid can be e.g., various combinations of water and detergent during the wash cycle or water (which may include additives) during the rinse cycle. Typically the fluid is recirculated during a given cycle using a pump. Fluid is collected at or near the bottom of the wash chamber and pumped back into the chamber through e.g., nozzles in the spray arms and other openings that direct the fluid against the articles to be cleaned or rinsed. Fluids used in e.g., the wash or rinse cycles may be heated. For example, hot water may be supplied to the dishwasher and/or the dishwasher may include one or more heat sources (e.g., electrically-resistant heating elements) for heating fluids used in wash or rinse cycle and for providing heat during a drying cycle.
Depending upon the level of soil upon the articles, fluids used during wash and rinse cycles will become contaminated with soils in the form of debris or particles that are carried with the fluid. In order to protect the pump and recirculate the fluid through the wash chamber, it is beneficial to filter the fluid so that relatively clean fluid is applied to the articles in the wash chamber and materials are removed or reduced from the fluid supplied to the pump.
For mechanical filtration, the selectivity of the filter to remove soil particles of different sizes is typically determined by providing fluid paths (such as pores or apertures) through a filter media that are smaller than the particles for which filtration is desired. Particles having a dimension larger than the width of the fluid paths will be trapped or prevented from passing through the filter while particles smaller than the width of the fluid path will generally pass through. Some particle sizes and/or types may be not harmful to the pump or spray assemblies and, therefore, can be allowed to pass into the pump inlet. However, while some smaller particles may not be harmful to the pump, leaving such particles in the wash or rinse fluid may not be acceptable as these particles may become deposited on the articles being washed/rinsed and thereby affect the user's perception of the cleanliness and/or appearance.
While larger particles can generally be readily removed from the fluid circulated through the wash chamber, challenges are presented in removing smaller particles—particularly as the particle size targeted for removal decreases. For example, if a dishwashing appliance is provided with a fine particle filter—such as one for removing particles 200 microns or larger—the filter can be prone to clogging particularly during the early stages of the cleaning process. During a pre-wash cycle or early stage of a wash cycle, a greater amount of larger food particles may be present on the articles placed in the wash chamber. A fine particle filter—such as one for removing particles 200 microns are larger—may become substantially clogged.
To unclog the filter, a conventional approach has been to drain the dirty fluid from the wash chamber to remove the particles clogging the filter. New—i.e. clean fluid—is then reintroduced for cycling again. Depending on the level of soil still present on the articles, yet another cycle of draining and refilling may have to be repeated. Unfortunately, this run, drain, and refill approach for unclogging a filter is inefficient as it requires the use of additional fluid (i.e. water) and, when the fluid is heated, additional energy is consumed as the fluid is drained and the new water is reheated. Of course, a filter media can be selected that only captures larger particles so that it clogs less, such as e.g., 0.30″ or larger, but this comes at the expense of losing the ability to remove smaller particles from the fluid and an associated effect on the resulting cleanliness of the articles.
Another challenge with filtration of the wash fluid is servicing of the filter and, more particularly, the filter media. Sometimes, for example, food particles can become lodged in the filter requiring that the filter be removed and either manually cleaned or replaced. Certain conventional dishwashing appliances do not have a filter that is readily accessible to the user and/or otherwise readily cleanable or serviceable.
Accordingly, a dishwasher appliance having filtering system for the removal of particles from the wash fluid would be useful. More particularly, a filtering system that can remove both large and fine particles (e.g., 50 to 100 micron or larger) without repeated draining and refilling to unclog the filter would be particularly beneficial. Such a filtering system using a filter that can also be readily accessed and serviced would also be useful.
The present invention provides a filtering system for a dishwashing appliance that can remove fine particles from the wash and rinse fluids. A filter cartridge is provided that can be rotated between filter media that are equipped for removal of different particulate sizes depending upon e.g., the cycle or stage of the cleaning process and/or anticipated particle size. The filter cartridge is positioned upstream from the pump inlet. In certain embodiments, the filter cartridge can be removable for servicing. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be apparent from the description, or may be learned through practice of the invention.
In one exemplary embodiment, the present invention provides a dishwashing appliance that includes a wash chamber having sump portion; at least one spray arm assembly for providing fluid onto articles placed in the wash chamber; a pump in fluid communication with the spray arm assembly, the pump having a pump inlet; and a filter system positioned in fluid communication the sump portion of the wash chamber and in fluid communication with, and upstream from, the pump inlet. The filter system includes a rotatable, cylindrically-shaped filter cartridge having a plurality of filter media positioned about the filter cartridge. Each of the filter media are configured for removing different sized particulates than the other filter media. A motor is in mechanical communication with the filter cartridge whereby the filter cartridge may be rotated to select between different filter media for filtering fluid travelling to the pump inlet from the filter system.
In another exemplary embodiment, the present invention provides a dishwashing appliance that includes a wash chamber having a sump portion. The sump portion includes a filter receptacle having a fluid outlet. A pump is provided for circulating fluid through the wash chamber, the pump having a pump inlet in fluid communication with the filter receptacle whereby fluid may be received by the pump from the filter receptacle. A rotatable filter cartridge is received into the filter receptacle, the filter cartridge defining a cylindrically-shaped wall surrounding an internal chamber and defining axial and circumferential directions. The cylindrically-shaped wall comprises a plurality of filter media positioned proximate to each other along the circumferential direction. A motor is connected with the rotatable filter cartridge and is configured for rotating the filter cartridge so that one of the plurality of filter media is positioned in fluid communication with the fluid outlet of the receptacle.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
As used herein, the term “article” may refer to, but need not be limited to, dishes, pots, pans, silverware, and other cooking utensils and items that can be cleaned in a dishwashing appliance. The term “wash cycle” is intended to refer to one or more periods of time during the cleaning process where a dishwashing appliance operates while containing articles to be washed and uses a detergent and water, preferably with agitation, to e.g., remove soil particles including food and other undesirable elements from the articles. The term “rinse cycle” is intended to refer to one or more periods of time during the cleaning process in which the dishwashing appliance operates to remove residual soil, detergents, and other undesirable elements that were retained by the articles after completion of the wash cycle. The term ‘drying cycle” is intended to refer to one or more periods of time in which the dishwashing appliance is operated to dry the articles by removing fluids from the wash chamber. The term “fluid” refers to a liquid used for washing and/or rinsing the articles and is typically made up of water that may include other additives such as detergent or other treatments.
Upper and lower guide rails 124, 126 are mounted on tub side walls 128 and accommodate roller-equipped rack assemblies 130 and 132. Each of the rack assemblies 130, 132 is fabricated into lattice structures including a plurality of elongated members 134 (for clarity of illustration, not all elongated members making up assemblies 130 and 132 are shown in
The dishwasher 100 further includes a lower spray-arm assembly 144 that is rotatably mounted within a lower region 146 of the wash chamber 106 and above a tub sump portion 142 so as to rotate in relatively close proximity to rack assembly 132. A mid-level spray-arm assembly 148 is located in an upper region of the wash chamber 106 and may be located in close proximity to upper rack 130. Additionally, an upper spray assembly 150 may be located above the upper rack 130.
The lower and mid-level spray-arm assemblies 144, 148 and the upper spray assembly 150 are part of a fluid circulation assembly 152 for circulating water and dishwasher fluid in the tub 104. The fluid circulation assembly 152 may also include a pump 154 located in a machinery compartment 140 located below the bottom sump portion 142 (i.e. bottom wall) of the tub 104, as generally recognized in the art. Each spray-arm assembly 144, 148 includes an arrangement of discharge ports or orifices for directing washing liquid onto dishes or other articles located in rack assemblies 130 and 132. The arrangement of the discharge ports in spray-arm assemblies 144, 148 provides a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the lower spray-arm assembly 144 provides coverage of dishes and other dishwasher contents with a washing spray.
The dishwasher 100 is further equipped with a controller 137 to regulate operation of the dishwasher 100. The controller may include one or more memory devices and one or more microprocessors, such as a general or special purpose microprocessors operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor.
The controller 137 may be positioned in a variety of locations throughout dishwasher 100. In the illustrated embodiment, the controller 137 may be located within a control panel area 121 of door 120 as shown in
It should be appreciated that the invention is not limited to any particular style, model, or configuration of dishwasher. The exemplary embodiment depicted in
As shown in
Referring now specifically to
Filtering system 200 removes soiled particles from the fluid that is recirculated through the wash chamber 106 during operation of dishwasher 100. After the fluid is filtered by passing through filter media of filter cartridge 206, it is fed to the inlet 155 of pump 154 for return to the wash chamber 106 by way of fluid circulation assembly 152. After being sprayed onto articles in the dishwashing appliance using one or more of spray elements 144, 148, and 150, the fluid eventually flows to sump portion 142.
Based on the shape of sump portion 142 (see
In order to avoid clogging of filter cartridge 206 during operation of the appliance 100, filter cartridge 206 is rotatable about axial direction A-A so that one of the plurality of filter media may be positioned to filter fluid exiting through fluid outlet 232. The filter media can be selected, for example, depending upon the size and/or amount of particulates expected in the fluid. More particularly, for this exemplary embodiment, the cylindrically-shaped wall 234 of filter cartridge 206 includes a first filter media 214, a second filter media 216, and a third filter media 218. Filter media 214, 216, and 218 are positioned proximate or adjacent to each other along the circumferential direction C. Each filter media is equipped to remove particles of a different size than the other filter media. The use on only three filter media is provided by way of example only. A different number of filter media other than three may be used with the present invention as well.
Referring now to
As shown in
By choosing the filter media so that each removes different sizes of particles from the fluid, filtering system 200 can be used to adjust the degree of filtration to the amount and size of particles present at different times during the cleaning process. For example, the filter media can be chosen such that progressively finer filtration can be used—i.e. filtering of smaller and smaller particles by selecting between filter media 214, 216, and 218—as the cleaning process for articles placed in appliance 100 progresses.
Accordingly, in one exemplary aspect of the present invention, first filter media 214 is configured for removing particles in the size range of about 0.030″ to about 0.060″ or equipped with holes of this size. For example, the filter media may be a screen or mesh having holes in the size range of about 0.030″ to about 0.060″. Second filter media 216 is configured for removing particles in the size range of about 300 micron to about 600 micron or e.g., is equipped with holes of this size. Third filter media 218 is configured for removing particles in the size range of about 50 micron to about 150 micron or equipped with holes of this size. These size ranges are provided by way of example only. Other ranges may be used in certain exemplary embodiments of the invention as well.
For this exemplary aspect of the invention, controller 137 provides a signal that causes motor 220 to position first filter media 214 at fluid outlet 232 of receptacle 204. Controller 137 then causes appliance 100 to execute a pre-wash cycle where only larger particles are removed (about 0.030″ to about 0.060″ or larger) without necessarily clogging filter cartridge 206. Next, in a main wash cycle, controller 137 provides a signal that causes motor 220 to position second filter media 216 at fluid outlet 232 such that smaller particles are removed (about 300 micron to about 600 micron or larger) without necessarily clogging filter cartridge 206. Finally, in a rinse cycle, controller 137 provides a signal that causes motor 220 to position third filter media 218 at fluid outlet 232 of receptacle 204 such that finest of particles are removed (about 50 micron to about 150 micron or larger) while avoiding clogs of filter cartridge 206. Other methods of operation including different steps and cycles may be used with the present invention as well.
Pressure drop in the fluid flowing through filter cartridge 206 is affected by hole size in the filter media as well as the percent of open area of the filter media. In certain exemplary embodiments of the invention, a percent of open area of about 30 percent may be used. In another embodiment, a percent of open area of about 40 percent may be used. In still another embodiment, a percent of open area of about 50 percent may be used.
Tests were conducted to determine the effect of different filter media on a user's ability to perceive soils or particles on dishes. Soiled dishes were washed with fluid filtration using different media as indicated in Table I below. Three test subjects were asked to evaluate the cleanliness of the dishes based on the grades shown in Table II. The results indicate that users can detect particles as small as 150 microns on dishes and may be able to detect particles smaller than 100 microns on dishes. Accordingly, a filtering system that can remove particles in the range of about 50 micron to about 150 microns without clogging is advantageous.
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
