Patent Application
20180325348
The present disclosure relates generally to dishwasher appliances, and more particularly to an improved drain pump assembly for dishwasher appliances.
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.
Conventional dishwasher appliances use two separate motors to operate a wash pump and a drain pump. However, additional motors take up more space, add cost, and require additional seals, thus increasing the likelihood of leaks and decreasing appliance reliability. Certain dishwasher appliances have eliminated the need for a second motor by using a single motor and a common drive shaft to rotate a wash pump impeller and a drain pump impeller. In this regard, the wash pump impeller and the drain pump impeller may be separated by a filter, and the motor may rotate in one direction to circulate wash fluid (i.e., the “wash direction”) and the other to drain wash fluid (i.e., the “drain direction”).
Because impellers have the tendency to pump fluid even when rotated in the reverse direction (albeit less efficiently), soil collected in the bottom of the sump may be churned or agitated during the wash cycle. However, cleaning efficiency and dishwasher operation is improved when food particles and soil are removed from the wash fluid circulating in the wash chamber. Certain dishwasher appliances have attempted to remove soils using complicated filtering systems, but these solutions may be expensive and/or not effective for containing such soils.
Accordingly, a dishwasher appliance that utilizes an improved drain pump assembly would be useful. More specifically, a drain pump assembly that collects or traps soils when the drive shaft is rotated in the wash direction would be particularly beneficial.
The present subject matter provides a dishwasher appliance having a sump for collecting wash fluid and a drain pump assembly for discharging wash fluid. The sump defines a drain basin and a drain cover is positioned over the drain basin to define a drain volute. A drain pump impeller is positioned within the drain volute on a drive shaft driven by a motor in a first direction during a wash cycle and in an opposite second direction during a drain cycle. During the wash cycle, soil enters the drain volute through a suction inlet defined by the drain cover where it is urged radially outward and trapped within the drain basin. When the motor operation is reversed, the drain pump impeller discharges the soiled wash fluid from the drain volute through a discharge conduit. Additional aspects and advantages of the invention will be set forth in part in the following description, may be apparent from the description, or may be learned through practice of the invention.
In accordance with one exemplary embodiment of the present disclosure, a drain pump assembly for a dishwasher appliance is provided. The drain pump assembly includes a sump for collecting wash fluid, the sump defining a drain basin proximate a bottom of the sump. A drain cover is positioned over the drain basin to define a drain volute, the drain cover defining a suction inlet to the drain volute. A drive shaft defines an axial direction and a radial direction perpendicular to the axial direction, the drive shaft extending through the suction inlet into the drain volute. A motor is operable to rotate the drive shaft in a first direction during a wash cycle and in a second direction during a drain cycle, the second direction being opposite the first direction. A drain pump impeller is positioned within the drain volute and coupled to the drive shaft.
In accordance with another exemplary embodiment of the present disclosure, a dishwasher appliance defining a vertical direction is provided. The dishwasher appliance includes a wash tub that defines a wash chamber and a sump for collecting wash fluid. A drive shaft defines an axial direction and a radial direction perpendicular to the axial direction. A motor is operable to rotate the drive shaft in a first direction during a wash cycle and in a second direction during a drain cycle, the second direction being opposite the first direction. A wash pump impeller is coupled to the drive shaft for providing a flow of wash fluid for cleaning articles placed within the wash chamber when the motor rotates in the first direction. The dishwasher further includes a drain pump assembly including a drain basin positioned proximate a bottom of the sump and a drain cover positioned over the drain basin to define a drain volute, the drain cover defining a suction inlet to the drain volute. A drain pump impeller is positioned within the drain volute and coupled to the drive shaft for discharging wash fluid when the motor rotates in the second direction.
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.
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 which a dishwashing appliance operates while containing the 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 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 “drain cycle” is intended to refer to one or more periods of time during which the dishwashing appliance operates to discharge soiled water from the dishwashing appliance. The term “wash 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 120, 122 are mounted on the first and second sides of tub 104 and accommodate roller-equipped rack assemblies 126 and 128. Each of the rack assemblies 126, 128 is fabricated into lattice structures including a plurality of elongated members 130 (for clarity of illustration, not all elongated members making up assemblies 126 and 128 are shown in
The dishwasher 100 further includes a lower spray arm assembly 140 that will be described in more detail below. Lower spray arm assembly 140 may be disposed in a lower region 142 of the wash chamber 106 and above a tub sump 144 so as to rotate in relatively close proximity to rack assembly 128. A mid-level spray arm assembly 146 is located in an upper region of the wash chamber 106 and may be located in close proximity to upper rack 126. Additionally, an upper spray assembly 148 may be located above the upper rack 126. As will be described in detail below, spray arm assemblies 140, 146, 148 may be part of a fluid circulation assembly 150 for circulating water and dishwasher fluid in the tub 104.
Each spray arm assembly 140, 146, 148 includes an arrangement of discharge ports or orifices for directing washing liquid received from fluid circulation assembly 150 onto dishes or other articles located in rack assemblies 126 and 128. The arrangement of the discharge ports, also referred to as jets, apertures, or orifices, may provide a rotational force by virtue of washing fluid flowing through the discharge ports. Alternatively, spray arm assemblies 140, 146, 148 may be motor-driven, or may operate using any other suitable drive mechanism. The resultant movement of the spray arm assemblies 140, 146, 148 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.
The dishwasher 100 is further equipped with a controller 156 to regulate operation of the dishwasher 100. The controller 156 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.
The controller 156 may be positioned in a variety of locations throughout dishwasher 100. In the illustrated embodiment, the controller 156 may be located within a control panel area 158 of door 114 as shown in
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
Referring now generally to
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.
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 140 and a bottom wall of sump 144, instead of beneath the sump 144, this design is inherently more compact than conventional designs.
According to an exemplary embodiment, fluid circulation assembly 150 may be vertically mounted within sump 144 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 (
Referring now to
In operation, wash pump impeller 182 draws wash fluid in from sump 144 and pumps it to a diverter assembly 190. Diverter assembly 190 may include a diverter disc 192 disposed within a diverter chamber 194 for selectively distributing the wash fluid to the spray arm assemblies 140, 146, 148. 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 a 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 140, 146, 148.
As illustrated in
As illustrated, filter 196 is a cylindrical and conical fine mesh filter constructed from a perforated stainless steel plate. 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 filter 196, but food particles entrained in the wash fluid do not pass through filter 196. However, according to alternative embodiments, filter 196 may be any structure suitable for filtering food particles from wash fluid passing through filter 196. For example, 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.
According to the illustrated exemplary embodiment, filter 196 defines an aperture through which drive shaft 176 extends. Wash pump impeller 182 is coupled to drive shaft 176 above filter 196 and a drain pump assembly (e.g., as described below) is coupled to drive shaft 176 below filter 196 along the vertical direction V. Fluid circulation assembly 150 may further include an inlet guide assembly 199 which is configured for accurately locating and securing filter 196 while allowing drive shaft 176 to pass through aperture and minimizing leaks between the filtered and unfiltered regions 197, 198 of sump 144. More specifically, as best illustrated in
Referring now generally to
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 filter 196. More specifically, drain volute 204 is defined by a drain basin 206 of sump 144 and a drain cover 208. In this regard, according to the exemplary embodiment, drain basin 106 defines a bottom wall 210 and a cylindrical side wall 212 of sump 144. Drain cover 208 is positioned over drain basin 206 and forms a fluid tight seal with side wall 212, e.g., by using an O-ring 214 or any other suitable sealing mechanism. According to the illustrated embodiment, the bottom of sump 144 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 144 and drain cover 208 define a frustum of a cone above drain basin 206.
As best shown in
Drain cover 208 defines a suction inlet 220 through which wash fluid may pass into drain volute 204. As illustrated, suction inlet 220 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 suction inlet 220 into drain volute 204 where it is coupled to drain pump impeller 202. More specifically, drain pump impeller 202 generally includes a hub 222 that is mounted to drive shaft 176. Hub 222 has a circular bore that is configured for receiving a bottom end of drive shaft 176. In an embodiment, drive shaft 176 and hub 222 may be keyed so as to be in cooperative engagement. In this regard, for example, drive shaft 176 may include one or more features, such as protrusions (not shown), in cooperative engagement with one or more features, such as recesses (not shown), in hub 222, or vice versa. In addition, one or more pins, retaining clips, or other mechanical retention devices may be used to fix hub 222 to drive shaft 176.
Notably, drain pump impeller 202 is coupled to the bottom portion of drive shaft 176 using a one-way clutch 226. 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, one-way clutch 226 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 one-way clutch 226 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 one-way clutch 226 and causing drain pump impeller 202 to rotate and discharge wash fluid.
Drain pump impeller 202 may further includes a plurality of vanes 224 that extend from hub 222 for pumping wash fluid. Vanes 224 may extend from a root 230 proximate hub 222 to a tip 232 substantially along the radial direction R. In addition, vanes 224 may be straight, curved, or any other suitable shape for achieve the desired pumping action and pressure heads when drain pump impeller 202 is rotated.
In general, drain volute 204 is oversized relative to drain pump impeller 202 to accommodate large food particles or other food soil that is drawn into drain volute 204. In this regard, the size of drain volute 204 relative to drain pump impeller 202 may be manipulated as desired depending on the application. For example, as best shown in
According to the exemplary embodiment, drain volute 204 defines a first diameter 240 and drain pump impeller 202 defines a second diameter 242. According to example embodiments, first diameter 240 is larger than second diameter 242. In this regard, first diameter 240 may be about five percent, ten percent, or greater than twenty percent larger than second diameter 242, e.g., to accommodate a larger size or quantity of food particles. In addition, to allow food particles to flow within drain volute 204 without binding between drain pump impeller 202 and drain basin 206 or drain cover 208, a vertical gap 244 may be defined between a top of drain pump impeller 202 and the drain cover 208.
As illustrated, suction inlet 220 is positioned at a center of drain cover 208 and is sized such that wash fluid and large food particles may pass 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 toward side wall 212 of 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 216.
Drain pump volute 202 and discharge conduit 216 are both positioned at the very bottom of sump 144, 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 216 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.
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 224 may be adjusted while remaining within the scope of the present subject matter. In addition, other embodiments may use more than four vanes having variable lengths, the vanes may have a different number and/or size of links, a different hinge configuration may be used, and biasing members may have a different size or configuration.
Drain pump assembly 200 as described above enables both a wash pump impeller and a drain pump impeller of a dishwasher fluid circulation system to be placed on a single drive shaft. In this manner, a single, reversible drive motor can rotate the drive shaft in a first direction for wash/rinse cycles and in the opposite direction for drain cycles. Furthermore, because the drain pump impeller rotates relatively slowly during the wash cycle, the drain pump impeller draws food particles and soil into the drain pump volute and urges it radially outward to trap it in the drain volute. In this manner, wash fluid circulated within the wash chamber 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 a discharge conduit for effective discharge when the drain pump impeller is rotated in the drain direction.
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.
