Fluid circulation assembly for a dishwasher appliance

Abstract

A dishwasher appliance includes a wash tub that defines a wash chamber, a sump for collecting wash fluid, a wash pump assembly in fluid communication with the sump for circulating a flow of wash fluid, a fine filter assembly fluidly coupled to the wash pump assembly, the fine filter assembly comprising a filter housing that defines a filter chamber and a screen filter, and a diverter assembly fluidly coupled to the wash pump assembly for selectively directing the flow of wash fluid, the diverter assembly comprising a first diverter outlet that is fluidly coupled to the filter chamber of the fine filter assembly.

Description

FIELD OF THE INVENTION

[0001] The present disclosure relates generally to dishwasher appliances, and more particularly to fluid circulation and filtering assemblies within dishwasher appliances.BACKGROUND OF THE INVENTION

[0002] Dishwasher appliances generally include a tub that defines a wash chamber. Rack assemblies can be mounted within the wash chamber of the tub for receipt of articles for washing. Wash fluid (e.g., various combinations of water and detergent along with optional additives) may be introduced into the tub where it collects in a sump space at the bottom of the wash chamber. During wash and rinse cycles, a pump may be used to circulate wash fluid to spray assemblies within the wash chamber that can apply or direct wash fluid towards articles disposed within the rack assemblies in order to clean such articles. During a drain cycle, a pump may periodically discharge soiled wash fluid that collects in the sump space and the process may be repeated.

[0003] With the increasing demand to reduce the water / energy usage of a dishwasher, conventional dishwasher appliances have generally shifted toward suction side passive filtration utilizing a manually cleaned fine filter. While this has successfully aided in reducing water / energy usage, it presents a problem of requiring the consumer to periodically clean this fine filter assembly. Many consumers are unaware of this required cleaning and instead receive lower than optimal wash performance. Certain conventional dishwashers utilize the circulation pump to automatically clean the fine filter assembly. However, these conventional designs require high energy / water usage due to the fact the pressured system is running at all times of circulation, resulting in elevated energy / water usage.

[0004] Accordingly, a dishwasher appliance that includes features that facilitate automated cleaning of a fine filter assembly would be useful. More specifically, a dishwasher including a fine filter wash system that is effective and water / energy efficient would be particularly beneficial.BRIEF DESCRIPTION OF THE INVENTION

[0005] 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.

[0006] In one exemplary embodiment, a dishwasher appliance is provided including a wash tub that defines a wash chamber, a sump for collecting wash fluid, a wash pump assembly in fluid communication with the sump for circulating a flow of wash fluid, a fine filter assembly fluidly coupled to the wash pump assembly, the fine filter assembly comprising a filter housing that defines a filter chamber and a screen filter, and a diverter assembly fluidly coupled to the wash pump assembly for selectively directing the flow of wash fluid, the diverter assembly comprising a first diverter outlet that is fluidly coupled to the filter chamber of the fine filter assembly.

[0007] In another exemplary embodiment, a fluid circulation assembly for a dishwasher appliance is provided. The dishwasher appliance defines a vertical direction and includes a wash tub that defines a wash chamber and a sump housing defining a sump for collecting wash fluid, the sump housing defining a drain basin. The fluid circulation assembly includes a wash pump assembly in fluid communication with the sump for circulating a flow of wash fluid, a fine filter assembly fluidly coupled to the wash pump assembly, the fine filter assembly comprising a filter housing that defines a filter chamber and a screen filter, and a diverter assembly fluidly coupled to the wash pump assembly for selectively directing the flow of wash fluid, the diverter assembly comprising a first diverter outlet that is fluidly coupled to the filter chamber of the fine filter assembly.

[0008] 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.BRIEF DESCRIPTION OF THE DRAWINGS

[0009] 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.

[0010] FIG. 1 provides a perspective view of an example dishwasher appliance of the with a door in a partially open position according to an example embodiment of the present subject matter.

[0011] FIG. 2 provides a side, cross sectional view of the example dishwasher appliance of FIG. 1 according to an example embodiment of the present subject matter.

[0012] FIG. 3 provides a perspective view of certain components of a fluid circulation assembly according to an example embodiment of the present subject matter.

[0013] FIG. 4 provides a perspective, cross-sectional view of the example fluid circulation assembly of FIG. 3 according to an example embodiment of the present subject matter.

[0014] FIG. 5 provides a perspective, cross-sectional view of the example fluid circulation assembly of FIG. 3 according to an example embodiment of the present subject matter.

[0015] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0016] 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.

[0017] As used herein, the terms “first,”“second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. The terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e., “A or B” is intended to mean “A or B or both”). In addition, here and throughout the specification and claims, range limitations may be combined and / or interchanged. Such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other. The singular forms “a,”“an,” and “the” include plural references unless the context clearly dictates otherwise.

[0018] Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “generally,”“about,”“approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of the methods or machines for constructing or manufacturing the components and / or systems. For example, the approximating language may refer to being within a 10 percent margin, i.e., including values within ten percent greater or less than the stated value. In this regard, for example, when used in the context of an angle or direction, such terms include within ten degrees greater or less than the stated angle or direction, e.g., “generally vertical” includes forming an angle of up to ten degrees in any direction, e.g., clockwise or counterclockwise, with the vertical direction V.

[0019] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” In addition, references to “an embodiment” or “one embodiment” does not necessarily refer to the same embodiment, although it may. Any implementation described herein as “exemplary” or “an embodiment” is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, 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 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.

[0020] As explained herein, aspects of the present subject matter are generally directed to a dishwasher including a pressured fine filter assembly and a diverter assembly that includes an independent diverter position that directs a flow of wash fluid into the pressurized fine filter assembly. For example, a circulation pump urges wash fluid and the diverter assembly includes a rotating diverting disk, which allows wash fluid to pump either to a plurality of spray devices to clean a dishware or a pressured fine filter. In this regard, a dedicated channel in a manifold may be located above the diverter disk which sends the wash fluid to a specific location, e.g., through a fine filter screen.

[0021] FIGS. 1 and 2 depict an exemplary domestic dishwasher or dishwashing appliance 100 that may be configured in accordance with aspects of the present disclosure. For the particular embodiment of FIGS. 1 and 2, the dishwasher 100 includes a cabinet 102 (FIG. 2) having a tub 104 therein that defines a wash chamber 106. As shown in FIG. 2, tub 104 extends between a top 107 and a bottom 108 along a vertical direction V, between a pair of side walls 110 along a lateral direction L, and between a front side 111 and a rear side 112 along a transverse direction T. Each of the vertical direction V, lateral direction L, and transverse direction T are mutually perpendicular to one another.

[0022] The tub 104 includes a front opening 114 and a door 116 hinged at its bottom for movement between a normally closed vertical position (shown in FIG. 2), wherein the wash chamber 106 is sealed shut for washing operation, and a horizontal open position for loading and unloading of articles from the dishwasher 100. According to exemplary embodiments, dishwasher 100 further includes a door closure mechanism or assembly 118 that is used to lock and unlock door 116 for accessing and sealing wash chamber 106.

[0023] As best illustrated in FIG. 2, tub side walls 110 accommodate a plurality of rack assemblies. More specifically, guide rails 120 may be mounted to side walls 110 for supporting a lower rack assembly 122, a middle rack assembly 124, and an upper rack assembly 126. As illustrated, upper rack assembly 126 is positioned at a top portion of wash chamber 106 above middle rack assembly 124, which is positioned above lower rack assembly 122 along the vertical direction V. Each rack assembly 122, 124, 126 is adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber 106, and a retracted position (shown in FIGS. 1 and 2) in which the rack is located inside the wash chamber 106. This is facilitated, for example, by rollers 128 mounted onto rack assemblies 122, 124, 126, respectively. Although a guide rails 120 and rollers 128 are illustrated herein as facilitating movement of the respective rack assemblies 122, 124, 126, it should be appreciated that any suitable sliding mechanism or member may be used according to alternative embodiments.

[0024] Some or all of the rack assemblies 122, 124, 126 are fabricated into lattice structures including a plurality of wires or elongated members 130 (for clarity of illustration, not all elongated members making up rack assemblies 122, 124, 126 are shown in FIG. 2). In this regard, rack assemblies 122, 124, 126 are generally configured for supporting articles within wash chamber 106 while allowing a flow of wash fluid to reach and impinge on those articles, e.g., during a cleaning or rinsing cycle. According to another exemplary embodiment, a silverware basket (not shown) may be removably attached to a rack assembly, e.g., lower rack assembly 122, for placement of silverware, utensils, and the like, that are otherwise too small to be accommodated by rack 122.

[0025] Dishwasher 100 further includes a plurality of spray assemblies for urging a flow of water or wash fluid onto the articles placed within wash chamber 106. More specifically, as illustrated in FIG. 2, dishwasher 100 includes a lower spray arm assembly 134 disposed in a lower region of wash chamber 106. Specifically, dishwasher 100 may include a sump housing 136 that is positioned at a bottom of tub 104, the sump housing 136 defining a sump space (referred to herein generally as a sump 138). According to example embodiments, lower spray arm assembly 134 is positioned in the lower region of wash chamber 106, e.g., just above sump 138, to rotate in relatively close proximity to lower rack assembly 122.

[0026] Similarly, a mid-level spray arm assembly 140 is located in an upper region of wash chamber 106 and may be located below and in close proximity to middle rack assembly 124. In this regard, mid-level spray arm assembly 140 may generally be configured for urging a flow of wash fluid up through middle rack assembly 124 and upper rack assembly 126. Additionally, an upper spray assembly 142 may be located above upper rack assembly 126 along the vertical direction V. In this manner, upper spray assembly 142 may be configured for urging and / or cascading a flow of wash fluid downward over rack assemblies 122, 124, and 126. As further illustrated in FIG. 2, upper rack assembly 126 may further define an integral spray manifold 144, which is generally configured for urging a flow of wash fluid substantially upward along the vertical direction V through upper rack assembly 126.

[0027] The various spray assemblies and manifolds described herein may be part of a fluid distribution system or fluid circulation assembly 150 for circulating water and wash fluid in the tub 104. More specifically, fluid circulation assembly 150 includes a pump 152 for circulating water and wash fluid (e.g., detergent, water, and / or rinse aid) in the tub 104. Pump 152 may be located within sump 138 or within a machinery compartment located below sump 138 of tub 104, as generally recognized in the art. Fluid circulation assembly 150 may include one or more fluid conduits or circulation piping for directing water and / or wash fluid from pump 152 to the various spray assemblies and manifolds. For example, as illustrated in FIG. 2, a primary supply conduit 154 may extend from pump 152, along rear 112 of tub 104 along the vertical direction V to supply wash fluid throughout wash chamber 106.

[0028] As illustrated, primary supply conduit 154 is used to supply wash fluid to one or more spray assemblies, e.g., to mid-level spray arm assembly 140 and upper spray assembly 142. However, it should be appreciated that according to alternative embodiments, any other suitable plumbing configuration may be used to supply wash fluid throughout the various spray manifolds and assemblies described herein. For example, according to another exemplary embodiment, primary supply conduit 154 could be used to provide wash fluid to mid-level spray arm assembly 140 and a dedicated secondary supply conduit (not shown) could be utilized to provide wash fluid to upper spray assembly 142. Other plumbing configurations may be used for providing wash fluid to the various spray devices and manifolds at any location within dishwasher appliance 100.

[0029] Each spray arm assembly 134, 140, 142, integral spray manifold 144, or other spray device may include an arrangement of discharge ports or orifices for directing wash fluid received from pump 152 onto dishes or other articles located in wash chamber 106. The arrangement of the discharge ports, also referred to as jets, apertures, or orifices, may provide a rotational force by virtue of wash fluid flowing through the discharge ports. Alternatively, spray arm assemblies 134, 140, 142 may be motor-driven, or may operate using any other suitable drive mechanism. Spray manifolds and assemblies may also be stationary. The resultant movement of the spray arm assemblies 134, 140, 142 and the spray from fixed manifolds provides coverage of dishes and other dishwasher contents with a washing spray. Other configurations of spray assemblies may be used as well. For example, dishwasher 100 may have additional spray assemblies for cleaning silverware, for scouring casserole dishes, for spraying pots and pans, for cleaning bottles, etc. One skilled in the art will appreciate that the embodiments discussed herein are used for the purpose of explanation only, and are not limitations of the present subject matter.

[0030] In operation, pump 152 draws wash fluid in from sump 138 and pumps it to a diverter assembly 156, e.g., which is positioned within sump 138 of dishwasher appliance. Diverter assembly 156 may include a diverter disk (not shown) disposed within a diverter chamber 158 for selectively distributing the wash fluid to the spray arm assemblies 134, 140, 142 and / or other spray manifolds or devices. For example, the diverter disk may have a plurality of apertures that are configured to align with one or more outlet ports (not shown) at the top of diverter chamber 158. In this manner, the diverter disk may be selectively rotated to provide wash fluid to the desired spray device.

[0031] According to an exemplary embodiment, diverter assembly 156 is configured for selectively distributing the flow of wash fluid from pump 152 to various fluid supply conduits, only some of which are illustrated in FIG. 2 for clarity. More specifically, diverter assembly 156 may include four outlet ports (not shown) for supplying wash fluid to a first conduit for rotating lower spray arm assembly 134, a second conduit for rotating mid-level spray arm assembly 140, a third conduit for spraying upper spray assembly 142, and a fourth conduit for supplying a fine filter assembly 220, which will be described in more detail below according to an exemplary embodiment.

[0032] The dishwasher 100 is further equipped with a controller 160 to regulate operation of the dishwasher 100. The controller 160 may include one or more memory devices and one or more microprocessors, such as 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. Alternatively, controller 160 may be constructed without using a microprocessor, e.g., using a combination of discrete analog and / or digital logic circuitry (such as switches, amplifiers, integrators, comparators, flip-flops, AND gates, and the like) to perform control functionality instead of relying upon software.

[0033] The controller 160 may be positioned in a variety of locations throughout dishwasher 100. In the illustrated embodiment, the controller 160 may be located within a control panel area 162 of door 116 as shown in FIGS. 1 and 2. In such an embodiment, input / output (“I / O”) signals may be routed between the control system and various operational components of dishwasher 100 along wiring harnesses that may be routed through the bottom of door 116. Typically, the controller 160 includes a user interface panel / controls 164 through which a user may select various operational features and modes and monitor progress of the dishwasher 100. In one embodiment, the user interface 164 may represent a general purpose I / O (“GPIO”) device or functional block. In one embodiment, the user interface 164 may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface 164 may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface 164 may be in communication with the controller 160 via one or more signal lines or shared communication busses.

[0034] It should be appreciated that the invention is not limited to any particular style, model, or configuration of dishwasher 100. The exemplary embodiment depicted in FIGS. 1 and 2 is for illustrative purposes only. For example, different locations may be provided for user interface 164, different configurations may be provided for rack assemblies 122, 124, 126, different spray arm assemblies 134, 140, 142 and spray manifold configurations may be used, and other differences may be applied while remaining within the scope of the present subject matter.

[0035] Referring now generally to FIGS. 3 through 5, fluid circulation assembly 150 will be described according to an example embodiment of the present subject matter. Fluid circulation assembly 150 may include a drive motor 170 that may be disposed within sump 138 of tub 104 and may be configured to rotate multiple components of dishwasher 100. As illustrated, drive motor 170 may be, for example, a brushless DC motor having a stator 172, a rotor 174, and a drive shaft 176 attached to rotor 174. A controller or control board (not shown) may control the speed of motor 170 and rotation of drive shaft 176 by selectively applying electric current to stator 172 to cause rotor 174 and drive shaft 176 to rotate. Although drive motor 170 is illustrated herein as a brushless DC motor, it should be appreciated that any suitable motor may be used while remaining within the scope of the present subject matter. For example, according to alternative embodiments, drive motor 170 may instead be a synchronous permanent magnet motor.

[0036] According to an example embodiment, drive motor 170 may be a variable speed motor. In this regard, drive motor 170 may be operated at various speeds depending on the current operating cycle of the dishwasher. For example, according to an exemplary embodiment, drive motor 170 may be configured to operate at any speed between a minimum speed, e.g., 1500 revolutions per minute (RPM), to a maximum rated speed, e.g., 4500 RPM. In this manner, use of a variable speed drive motor 170 enables efficient operation of dishwasher 100 in any operating mode. Thus, for example, the drain cycle may require a lower rotational speed than a wash cycle and / or rinse cycle. A variable speed drive motor 170 allows impeller rotation at the desired speeds while minimizing energy usage and unnecessary noise when drive motor 170 does not need to operate at full speed.

[0037] According to an exemplary embodiment, drive motor 170 and all its components may be potted. In this manner, drive motor 170 may be shock-resistant, submersible, and generally more reliable. Notably, because drive motor 170 is mounted inside wash chamber 106 and is completely submersible, no seals are required and the likelihood of leaks is reduced. In addition, because drive motor 170 is mounted in the normally unused space between lower spray arm assembly 134 and a bottom wall of sump 138, instead of beneath the sump 138, this design is inherently more compact than conventional designs.

[0038] According to an exemplary embodiment, fluid circulation assembly 150 may be vertically mounted within sump 138 of wash chamber 106. More particularly, drive motor 170 of fluid circulation assembly 150 may be mounted such that drive shaft 176 is oriented along vertical direction V of dishwasher 100. More particularly, drive shaft 176 may define an axial direction A, a radial direction R, and a circumferential direction C (FIG. 3), with the axial direction A being parallel to the vertical direction V of the dishwasher 100. Drive shaft 176 may be rotatably supported by upper and lower bearings and extends out of a bottom of drive motor 170 toward a bottom of sump 138.

[0039] As illustrated, drive shaft 176 is configured for driving a circulation or wash pump assembly 180. Wash pump assembly 180 may generally be configured for circulating wash fluid within wash chamber 106 during wash and / or rinse cycles. More specifically, wash pump assembly 180 may include a wash pump impeller 182 disposed on drive shaft 176 within a pump housing 184. Pump housing 184 defines a pump intake 186 for drawing wash fluid into wash pump impeller 182. According to the illustrated embodiment, pump intake 186 is facing downward along the vertical direction V and is located very near the bottom of sump 138. In this manner, the amount of water required to prime and operate wash pump assembly 180 is minimized. This is particularly advantageous when running low water cycles for the purpose of water and energy savings.

[0040] As shown in FIG. 5, pump housing 184 is in fluid communication with a supply conduit 188 through which pressurized wash fluid may be recirculated through fluid circulation assembly 150. More specifically, according to the illustrated embodiment, wash pump impeller 182 draws wash fluid in from sump 138 and pumps it through supply conduit 188 to a diverter assembly 190 (such as diverter assembly 156) which generally distributes the flow of wash fluid as desired within dishwasher 100.

[0041] As shown in FIG. 5, diverter assembly 190 may include a diverter disc 192 disposed within a diverter chamber 194 (such as diverter chamber 158). Diverter chamber 194 is fluidly coupled to supply conduit 188, such that rotating diverter disc 192 may selectively distribute the flow of wash fluid to the spray arm assemblies 134, 140, 142, fine filter assembly 220 (described in more detail below), or any other fluid conduit coupled to diverter chamber 194. More particularly, diverter disc 192 may be rotatably mounted about the vertical direction V. Diverter disc 192 may have a plurality of apertures that are configured to align with one or more outlet ports at the top of diverter chamber 194. In this manner, diverter disc 192 may be selectively rotated to provide wash fluid to spray arm assemblies 134, 140, 142 or fine filter assembly 220.

[0042] As illustrated, fluid circulation assembly 150 further includes a filter screen or coarse filter 196. In general, coarse filter 196 may define an unfiltered region 197 and a filtered region 198 within sump 138. During a wash or rinse cycle, wash fluid sprayed on dishes or other articles within wash chamber 106 falls into the unfiltered region 197. Wash fluid passes through coarse filter 196 which removes coarse food particles, resulting in relatively clean wash fluid within the filtered region 198. As used herein, “food particles” refers to food soil, particles, sediment, or other contaminants in the wash fluid which are not intended to travel through coarse filter 196. Thus, a food particle seal may allow water or other wash fluids to pass from the unfiltered region 197 to the filtered region 198 while preventing food particles entrained within that wash fluid from passing along with the wash fluid.

[0043] As illustrated, coarse filter 196 is constructed from a perforated stainless steel plate. Coarse filter 196 may include a plurality of perforated holes, e.g., approximately 15 / 1000 of an inch in diameter, such that wash fluid may pass through coarse filter 196, but food particles entrained in the wash fluid do not pass through coarse filter 196. However, according to alternative embodiments, coarse filter 196 may be any structure suitable for filtering food particles from wash fluid passing through coarse filter 196. For example, coarse filter 196 may be constructed from any suitably rigid material, may be formed into any suitable shape, and may include apertures of any suitable size for capturing particulates.

[0044] Referring still to FIGS. 3 through 5, a drain pump assembly 200 according to an exemplary embodiment of the present subject matter will be described. Drain pump assembly 200 may generally be configured for periodically discharging soiled wash fluid from dishwasher 100. Although illustrated and described as part of fluid circulation assembly 150, it should be appreciated that aspects of drain pump assembly 200 may be used in any impeller assembly in any application where it is desirable to selectively pump a fluid. In this regard, drain pump assembly 200 is only one exemplary configuration used for the purpose of explaining aspects of the present subject matter and is not intended to limit the scope of the invention in any manner.

[0045] Drain pump assembly 200 may include a drain pump impeller 202 coupled to a bottom portion of drive shaft 176 and positioned within a drain volute 204 below coarse filter 196. More specifically, drain volute 204 is defined by a drain basin 206 of sump 144 and a drain cover 208 that positioned over drain basin 206 and forms a fluid tight seal with drain basin 206, e.g., by using an O-ring or any other suitable sealing mechanism. According to the illustrated embodiment, the bottom of sump 138 and drain cover 208 define a seamless transition and are cone-shaped to help funnel food particles toward drain volute 202. For example, as illustrated, sump 138 and drain cover 208 define a frustum of a cone above drain basin 206.

[0046] As illustrated, drain pump assembly 200 further includes a discharge conduit 210 (FIG. 3) that extends from drain basin 206 and is in fluid communication with drain volute 204. Drain cover 208 defines a drain inlet 212 through which wash fluid may pass into drain volute 204. As illustrated, drain inlet 212 is a circular aperture in the center of drain cover 208, but other sizes and geometries may be used according to alternative embodiments. As illustrated drive shaft 176 passes through drain inlet 212 into drain volute 204 where it is coupled to drain pump impeller 202. During a drain cycle, drain pump impeller 202 draws soiled wash fluid through drain inlet 212 into drain volute 204 and discharges it through discharge conduit 210.

[0047] Notably, drain pump impeller 202 is coupled to the bottom portion of drive shaft 176 using a one-way clutch (not shown). In this regard, during a wash / rinse cycle, drive motor 170 rotates in one direction, pumping filtered wash fluid using wash pump impeller 182. However, the one-way clutch is disengaged, so drain pump impeller 202 does not rotate at the same speed. Instead, drain pump impeller 202 may rotate at a decreased speed, e.g., due to some friction between the one-way clutch and drive shaft 176. According to alternative embodiments, drain pump impeller 202 may remain stationary during the wash cycle or may rotate at the same speed as wash pump impeller 182. In both cases, soil and food particles will have a tendency to collect within drain volute 204, as described herein. By contrast, during a drain cycle, drive motor 170 rotates in the opposite direction, thereby engaging the one-way clutch and causing drain pump impeller 202 to rotate and discharge wash fluid.

[0048] As illustrated, a drain inlet 212 is positioned on one side of sump 138 and may be covered by coarse filter 196 which may be a coarse filter for removing large food particles from the wash fluid before the wash fluid passes into drain volute 204. However, drain cover 208 also acts as a barrier to prevent soil that collects around a perimeter of drain volute 204 from escaping drain volute 204, e.g., along the vertical direction V. In this manner, as drain pump impeller 202 rotates, soil and food particles are urged radially outward within drain basin 206 where they are trapped and collect until a drain cycle is initiated. When drive shaft 176 is rotated in the drain direction, wash fluid and soils collected in drain volute 204 are quickly and efficiently expelled through discharge conduit 210.

[0049] Drain pump volute 202 and discharge conduit 210 are both positioned at the very bottom of sump 138, at the lowest portion of fluid circulation assembly 150, providing several operational advantages. Specifically, heavier soil tends to fall toward drain volute 204 where wash fluid and food particles are collected. During a drain cycle, drain pump impeller 202 is rotated and soiled wash fluid is discharged from dishwasher 100 through a discharge conduit 210 such that complete draining of soiled wash fluid may be achieved. After some or all of the soiled wash fluid is discharged, fresh water and / or wash additives may be added and the wash or rinse cycle may be repeated.

[0050] It should be appreciated that drain pump assembly 200 is used only for the purpose of explaining aspects of the present subject matter. Modifications and variations may be made to drain pump assembly 200 while remaining within the scope of the present subject matter. For example, the number, size, spacing, and configuration of vanes of drain pump impeller 202 may be adjusted while remaining within the scope of the present subject matter.

[0051] Drain pump assembly 200 as described above enables both wash pump impeller 182 and drain pump impeller 202 of fluid circulation system 150 to be placed on a single drive shaft 176. In this manner, a single, reversible drive motor 170 can rotate drive shaft 176 in a first direction for wash / rinse cycles and in the opposite direction for drain cycles. More specifically, according to the illustrated embodiment, drive motor 170 and wash pump assembly 180 are positioned within filtered region 198, while drain pump assembly 200 is positioned within unfiltered region 197. Furthermore, because drain pump impeller 202 rotates relatively slowly during the wash cycle, drain pump impeller 202 draws food particles and soil into drain volute 204 and urges them radially outward to trap them in drain volute 204. In this manner, wash fluid circulated within wash chamber 106 has a lower soil content and can facilitate more effective cleaning of articles placing in the dishwashing racks. In addition, the soil is trapped or contained proximate discharge conduit 210 for effective discharge when drain pump impeller 202 is rotated in the drain direction.

[0052] Referring still to FIGS. 3 through 5, dishwasher appliance 100 may include a fine filter assembly 220 that is fluidly coupled to wash pump assembly 180 for further filtering a flow of wash fluid. In this regard, fine filter assembly 220 is generally positioned downstream of coarse filter 196 and is configured to filter finer particulates or soils from the flow of wash fluid. Although an example construction of fine filter assembly 220 is described herein, it should be appreciated that variations and modifications may be made while remaining within the scope of the present subject matter.

[0053] As shown, fine filter assembly 220 generally includes a filter housing 222 that defines a filter chamber 224. Specifically, as illustrated, filter housing 222 may include a lower manifold housing 226 and an upper manifold housing 228 that are joined to define filter chamber 224 which is in fluid communication with supply conduit 188 through diverter chamber 194. In this manner, fine filter assembly 220 is generally configured for receiving a flow of wash fluid when diverter disc 192 is positioned such that supply conduit 188 is in fluid communication with filter chamber 224.

[0054] A screen filter, such as a fine screen filter 230, may be positioned on a top end of filter housing 222. In this manner, as a flow of wash fluid floods filter chamber 224, fine screen filter 230 may remove fine particulates or soils before the wash fluid flows back into wash chamber 106, thereby facilitating an improved cleaning process. According to an example embodiment, fine screen filter 230 may be constructed from a fine steel mesh or a perforated stainless steel plate and may define a plurality of perforated holes or apertures smaller than those defined in coarse filter 196. For example, the apertures of fine screen filter 230 may be approximately 5 / 1000 of an inch in diameter, such that finer particulates may be removed from the wash fluid. However, according to alternative embodiments, fine screen filter 230 may be any structure suitable for filtering food particles from wash fluid passing through fine screen filter 230. For example, fine screen filter 230 may be constructed from any suitably rigid material, may be formed into any suitable shape, and may include apertures of any suitable size for capturing particulates.

[0055] During a fine filtering cycle, diverter assembly 190 may align an aperture of diverter disc 192 with an inlet 232 of filter chamber 224 such that the entire flow of wash fluid is passed into filter chamber 224. The flow of wash fluid may then flow through fine screen filter 230 where fine soils are removed before that wash fluid is reintroduced to wash chamber 106. Notably, it may be desirable to periodically clean fine screen filter 230, e.g., to decrease clogging, improve filter efficiency, and reduce energy consumption and strain on wash pump assembly 180. Accordingly, aspects of the present subject matter are directed to features for facilitating such periodic cleaning of fine screen filter 230.

[0056] In this regard, for example, dishwasher appliance 100 may include one or more spray arms or spray nozzles for directing a flow of cleaning fluid down onto fine screen filter 230. Specifically, according to the illustrated embodiment, lower spray arm assembly 134 may be in fluid communication with supply conduit 188 when diverter disc 192 is in a second position or a screen cleaning position. Lower spray arm assembly 134 may define one or more cleaning ports 234 (FIG. 3) that direct wash fluid downward through fine screen filter 230, e.g., in the reverse direction to dislodge collecting particulates and soils from fine screen filter 230. These soils may be collected within filter chamber 224 and may be discharged through a discharge port 236 that is defined in lower manifold housing 226.

[0057] In this regard, discharge port 236 may be an aperture defined at a bottom of filter housing 222 and which may be fluidly coupled to drain basin 206 in any suitable manner. Notably, during a fine filtering process, it may be desirable to close discharge port 236 (e.g., to force wash fluid and soils through fine screen filter 230), whereas during a filter cleaning process, it may be desirable to open discharge port 236 (e.g., to facilitate the egress of collected soils). Accordingly, fine filter assembly 220 may further include a flow regulating valve that closes discharge port 236 when filter chamber 224 is pressurized during a filtering cycle but which opens during the filter cleaning process.

[0058] According to an example embodiment, the flow regulating valve is a spring-loaded flapper valve 238. This flapper valve 238 may be biased toward the open position such that it is only closed when diverter assembly 190 directs the flow of wash fluid into filter chamber 224 during a fine filtering process. When fine screen filter 230 is being cleaned, flapper valve 238 may open to permit dislodged soils to flow along with wash fluid through discharge port 236 and into drain volute 204. It should be appreciated that other flow regulating valves may be used while remaining within the scope of the present subject matter, such as umbrella valves, solenoid valves, etc.

[0059] Dishwasher appliance 100 may regulate operation of diverter assembly 190 to perform a fine filtering process and / or a filter screening process at any suitable time during an operating cycle. For example, due to the increased amount of soil and debris within the wash fluid during the early stages of an operating cycle (e.g., during the pre-wash cycle), it may be desirable to operate the fine filtering cycle after this coarse debris has been removed by coarse filter 196 or after these soils have been discharged through drain pump assembly 200. Accordingly, controller 160 may be configured to operate diverter assembly 190 to direct the flow of wash fluid into filter chamber 224 after a pre-wash cycle has been completed. The filter cleaning cycle may be run subsequent to the fine filtering cycle.

[0060] 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 language of the claims.

Claims

1. A dishwasher appliance defining a vertical direction, the dishwasher appliance comprising:a wash tub that defines a wash chamber;a sump for collecting wash fluid;a wash pump assembly in fluid communication with the sump for circulating a flow of wash fluid;a fine filter assembly fluidly coupled to the wash pump assembly, the fine filter assembly comprising a filter housing that defines a filter chamber and a screen filter; anda diverter assembly fluidly coupled to the wash pump assembly for selectively directing the flow of wash fluid, the diverter assembly comprising a first diverter outlet that is fluidly coupled to the filter chamber of the fine filter assembly.

2. The dishwasher appliance of claim 1, wherein the fine filter assembly is positioned on top of the wash pump assembly.

3. The dishwasher appliance of claim 1, wherein the screen filter is positioned on top of the filter housing.

4. The dishwasher appliance of claim 1, wherein the filter housing defines a discharge port, the diverter assembly further comprising:a flow regulating valve that closes the discharge port when the filter chamber is pressurized.

5. The dishwasher appliance of claim 4, wherein the flow regulating valve is a spring-loaded flapper valve.

6. The dishwasher appliance of claim 4, wherein the discharge port is fluidly coupled to a drain basin.

7. The dishwasher appliance of claim 1, further comprising a lower spray arm in fluid communication with a supply conduit, wherein the screen filter is positioned below the lower spray arm.

8. The dishwasher appliance of claim 7, wherein the supply conduit is in fluid communication with a second diverter outlet of the diverter assembly.

9. The dishwasher appliance of claim 1, wherein the screen filter is a fine filter.

10. The dishwasher appliance of claim 1, wherein the diverter assembly comprises a second diverter outlet, wherein the flow of wash fluid passes through the first diverter outlet when the diverter assembly is in a first position and through the second diverter outlet when the diverter assembly is in a second position.

11. The dishwasher appliance of claim 1, further comprising a controller in operative communication with the wash pump assembly for regulating a diverter position, the controller being configured to:operate the diverter assembly to direct the flow of wash fluid into the filter chamber after a pre-wash cycle has been completed.

12. A fluid circulation assembly for a dishwasher appliance, the dishwasher appliance defining a vertical direction and comprising a wash tub that defines a wash chamber and a sump housing defining a sump for collecting wash fluid, the sump housing defining a drain basin, the fluid circulation assembly comprising:a wash pump assembly in fluid communication with the sump for circulating a flow of wash fluid;a fine filter assembly fluidly coupled to the wash pump assembly, the fine filter assembly comprising a filter housing that defines a filter chamber and a screen filter; anda diverter assembly fluidly coupled to the wash pump assembly for selectively directing the flow of wash fluid, the diverter assembly comprising a first diverter outlet that is fluidly coupled to the filter chamber of the fine filter assembly.

13. The fluid circulation assembly of claim 12, wherein the fine filter assembly is positioned on top of the wash pump assembly.

14. The fluid circulation assembly of claim 12, wherein the screen filter is positioned on top of the filter housing.

15. The fluid circulation assembly of claim 12, wherein the filter housing defines a discharge port, the diverter assembly further comprising:a flow regulating valve that closes the discharge port when the filter chamber is pressurized.

16. The fluid circulation assembly of claim 15, wherein the flow regulating valve is a spring-loaded flapper valve.

17. The fluid circulation assembly of claim 15, wherein the discharge port is fluidly coupled to a drain basin.

18. The fluid circulation assembly of claim 12, further comprising a lower spray arm in fluid communication with a supply conduit, wherein the screen filter is positioned below the lower spray arm.

19. The fluid circulation assembly of claim 12, wherein the diverter assembly comprises a second diverter outlet, wherein the flow of wash fluid passes through the first diverter outlet when the diverter assembly is in a first position and through the second diverter outlet when the diverter assembly is in a second position.

20. The fluid circulation assembly of claim 12, further comprising a controller in operative communication with the wash pump assembly for regulating a diverter position, the controller being configured to:operate the diverter assembly to direct the flow of wash fluid into the filter chamber after a pre-wash cycle has been completed.

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