Patent Application
20180132694
The present disclosure relates generally to dishwasher appliances, and more particularly to improved pump inlet assemblies 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. A sump space may be positioned below the wash chamber for collecting wash fluid (e.g. various combinations of water and detergent along with optional additives). During wash and rinse cycles, a pump can circulate wash fluid from the sump to spray assemblies within the wash chamber. The spray assemblies can apply or direct the wash fluid towards articles disposed within the rack assemblies in order to clean such articles.
It is often desirable to know the level of wash fluid within a wash chamber of a dishwasher, e.g., to prevent overflow conditions and to ensure the level of wash fluid is sufficient for optimal pump operation. Conventional dishwasher appliances may rely on the time a water inlet valve is open to determine how much wash fluid is in the dishwasher. However, variations in the valves or water supply lines, or variation in the water supply pressure can result in inaccurate water levels. Alternatively, some dishwashers use a variety of sensors for determining the level of wash fluid within the dishwasher, e.g., float sensors, capacitive sensors, optical sensors, etc. However, such sensors add significant costs and sometime result in reliability issues when exposed to soiled wash fluid.
Certain dishwasher appliances have incorporated the use of pressure sensors positioned within the sump of the dishwasher for determining the level of the wash fluid. However, such pressure sensors must be protected from soil in the wash fluid to prevent contamination. For example, such pressure sensors are often connected to the sump with a tube to provide an airgap between the wash fluid and the sensor. However, installing these tubes and forming the sump to provide an airgap between the wash fluid and the sensor increases potential leak points in the dishwasher.
Accordingly, dishwasher appliances having improved systems and methods for determining a level of wash fluid within the dishwasher would be useful. More specifically, a dishwasher having a pump inlet assembly that enables reliable pressure sensing with minimal leak points would be particularly beneficial.
The present subject matter provides a pump inlet assembly and method of operating a dishwasher appliance. The pump inlet assembly includes an inlet conduit providing fluid communication between a sump and a pump. The inlet conduit defines an integrally formed boss which is coupled with a sensor housing using an overmolding process. A pressure sensor is positioned in the sensor housing and is protected from wash fluid by an airgap defined by the boss. The measured pressure may be used to determine the water level within the dishwasher when the pump is not operating and the suction pressure within the inlet conduit when the pump is operating. The inlet conduit, boss, pressure sensor, and pump housing may be integrally formed by injection molding and/or overmolding processes to reduce costs and the likelihood of leaks. 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 dishwasher appliance defining a vertical direction is provided. The dishwasher appliance includes a wash tub that defines a wash chamber, a pump for circulating a flow of wash fluid for cleaning articles placed within the wash chamber, and a sump positioned below the wash chamber along the vertical direction, the sump being configured for collecting wash fluid. A pump inlet assembly includes an inlet conduit providing fluid communication between the sump and the pump and a pressure sensor for measuring a pressure of the wash fluid in the inlet conduit. A boss is integrally molded with the inlet conduit and defines an airgap. A sensor housing is coupled to the boss above the airgap using an overmolding process, the sensor housing being configured for receiving the pressure sensor.
In accordance with another exemplary embodiment of the present disclosure, a method of manufacturing a fluid circulation assembly of a dishwasher appliance is provided. The dishwasher appliance includes a pump for circulating a flow of wash fluid for cleaning articles placed within a wash chamber and a sump positioned below the wash chamber for collecting wash fluid. The method includes providing a sensor housing configured for receiving a pressure sensor and overmolding an inlet conduit onto the sensor housing, the inlet conduit being coupled to the sensor housing by an integral boss which defines an airgap. The method further includes positioning the inlet conduit to establish fluid communication between the sump and the pump and positioning the pressure sensor in the sensor housing for measuring a pressure of the wash fluid in the inlet conduit.
According to still another embodiment of the present subject matter, a method of operating a dishwasher appliance is provided. The dishwasher appliance includes a pump for circulating a flow of wash fluid for cleaning articles placed within a wash chamber, a sump positioned below the wash chamber for collecting wash fluid, an inlet conduit providing fluid communication between the sump and the pump, and a sensor housing formed integrally with the inlet conduit and being configured for receiving a pressure sensor. The method includes measuring the pressure of wash fluid in the inlet conduit and determining whether the pump is operating.
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 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 additives such as e.g., detergent or other treatments. The use of the terms “top” and “bottom,” or “upper” and “lower” herein are used for reference only as exemplary embodiments disclosed herein are not limited to the vertical orientation shown nor to any particular configuration shown; other constructions and orientations may also be used.
Upper and lower guide rails 120, 122 are mounted on tub side walls 124 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 is rotatably mounted within a lower region 142 of the wash chamber 106 and above a tub sump portion 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.
The lower and mid-level spray-arm assemblies 140, 146 and the upper spray assembly 148 are part of a fluid circulation assembly 150 for circulating water and dishwasher fluid in the tub 104. The fluid circulation assembly 150 also includes a pump 152 positioned in a machinery compartment 154 located below the tub sump portion 144 (i.e., bottom wall) of the tub 104, as generally recognized in the art. Pump 152 receives wash fluid from sump 144 and provides a flow of wash fluid to a diverter 160. The flow of wash fluid enters diverter 160 through an inlet 162, and diverter 160 directs the flow of wash fluid to one or more spray assemblies throughout the dishwasher, e.g., to spray assemblies 140, 146, and 148, or to a silverware spray assembly.
Each spray-arm assembly 140, 146 includes an arrangement of discharge ports or orifices for directing washing liquid received from diverter 160 onto dishes or other articles located in rack assemblies 126 and 128. The arrangement of the discharge ports in spray-arm assemblies 140, 146 provides a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the spray-arm assemblies 140, 146 and the operation of spray assembly 148 using fluid from diverter 160 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 166 to regulate operation of the dishwasher 100. The controller 166 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 166 may be positioned in a variety of locations throughout dishwasher 100. In the illustrated embodiment, the controller 166 may be located within a control panel area 168 of door 110 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 to
Referring now also to
Boss 212 is configured to be coupled to a sensor housing 214. More specifically, according to the exemplary embodiment, boss 212 and inlet conduit 210 are overmolded onto sensor housing 214 to form a single integral part. Overmolding is a process by which a previously molded part proceeds through a second molding process to add an additional feature, material, or component. After the overmolding process is complete, pump inlet assembly 200 is a single, integral component that has few or no leak points and is simple and easy to install.
According to the illustrated embodiment, pump inlet assembly 200 is constructed by first injection molding sensor housing 214 using a first material and then overmolding boss 212 and inlet conduit 210 onto sensor housing 214 using a second material. According to the exemplary embodiment, inlet conduit 210 and boss 212 are constructed of a softer material than sensor housing 214, thus resulting in a single part having two portions with different hardnesses. However, it should be appreciated that the materials used and the method of construction are described herein only for explaining aspects of the present subject matter. Pump inlet assembly 200 may use other materials having different hardness, and may be constructed in a different manner while remaining in the scope of the present invention. For example, sensor housing 214 could be overmolded onto inlet conduit 210, the components could be made from the same material, etc.
A pressure sensor 216 may be inserted into sensor housing 214 for measuring the pressure of wash fluid in inlet conduit 210, as described below. Pressure sensor 216 may be any suitable sensor for measuring the pressure of the wash fluid in inlet conduit 210. For example, pressure sensor 216 may be a microelectromechanical (MEMS) type sensor, a bellow type sensor, etc. According to the exemplary embodiment, pressure sensor 216 may be coupled to controller 166, which may be configured for controlling dishwasher 100 in response to feedback from pressure sensor 216.
According to the illustrated embodiment, pump inlet assembly 200 is connected from a bottom portion of sump 144 and is connected directly to impeller housing 202. More specifically, ends of inlet conduit 210 are connected to sump 144 and impeller housing 202 using screw clamps. However, according to alternative exemplary embodiments, pump inlet assembly 200 may be overmolded onto sump 144, impeller housing 202, or both. In this manner, one or both screw clamps may be eliminated, assembly may be simplified, and the likelihood of leaks may be reduced even further.
Referring now generally to
After assembling pump inlet assembly 200 and using it to couple sump 144 and pump 152, pressure sensor 216 may be used to reliably and accurately measure the pressure of wash fluid in inlet conduit 210. The pressure measurement may be correlated to various performance characteristics of dishwasher 100 and may be used to control dishwasher operation. For example, dishwasher 100 may include a fluid inlet (not shown) that supplies water or wash fluid to wash chamber 106 for use by fluid circulation assembly 150 during operation. The fluid inlet may be controlled in response to pressure measurements, for example, to adjust the level of wash fluid within wash chamber 106, as described below.
Method 250 includes, at step 252, providing a sensor housing configured for receiving a pressure sensor. For example, according to one embodiment, sensor housing may be injection molded using acrylonitrile butadiene styrene (ABS) thermoplastic, polypropylene, or any other suitable plastic or material. Step 254 includes overmolding an inlet conduit onto the sensor housing. As explained above, the inlet conduit is a circular conduit having a channel or boss extending from the center. The boss extends between and couples the inlet conduit and the sensor housing. In addition, the boss defines an airgap between the inlet conduit and the sensor housing.
Method 250 further includes, at step 256, positioning the inlet conduit to establish fluid communication between the sump and the pump. For example, the inlet conduit may be fluidly coupled at a bottom portion of sump and to the impeller housing of the pump. At step 258, method 250 includes positioning the pressure sensor in the sensor housing for measuring a pressure of the wash fluid in the inlet conduit.
Now that the construction and configuration of fluid circulation assembly 150 and pump inlet assembly 200 according to an exemplary embodiment of the present subject matter has been presented, an exemplary method 300 for operating a dishwasher according to an exemplary embodiment of the present subject matter is provided. Method 300 can be used to operate any suitable dishwashing appliance or other water consuming appliance. For example, method 300 may be utilized to operate dishwasher 100 (
Referring now to
For example, method 300 includes, at step 330, determining a fluid level within the sump based on the measured pressure of the wash fluid when the pump is not operating. In this regard, the measured pressure can correspond to a particular height of wash fluid within a chamber of a dishwashing appliance. According to exemplary embodiments, a calibration curve may be used to relate the measured pressure and the fluid level within the sump. At step 332, method 300 includes determining that the fluid level within the sump has exceeded a predetermined threshold and step 334 includes initiating an action in response to determining that the fluid level has exceeded the predetermined threshold.
According to one embodiment, the predetermined threshold is a maximum fluid level of the dishwasher and the initiated action is shutting off a flow of fluid into the dishwasher. Using such a limit may prevent overflow conditions. Alternatively, the predetermined threshold may be a desired fill amount for an operating cycle of the dishwasher and the initiated action is shutting off a flow of fluid into the dishwasher and starting the operating cycle. In this regard, for example, if only a small amount of water is required for a particular operating cycle, method 300 may be used to supply only that amount of wash fluid, thereby resulting in energy and water savings.
According to another exemplary embodiment, method 300 includes, at step 340, determining a suction pressure of the pump based on the measured suction pressure of the wash fluid when the pump is operating. The suction pressure may be used to confirm proper operation of dishwasher and the circulation pump. Method further includes, at step 342, determining that the measured suction pressure is unstable, and at step 344, initiating an action based on the determination that the measured suction pressure is unstable. As used herein, suction pressure is considered “unstable” when it varies beyond a predetermined range relative to the desired operating pressure. For example, the measured suction pressure may be unstable if the measured suction pressure falls below a low pressure threshold, exceeds a high pressure threshold, or varies beyond a variability limit. The action taken in response to the determination that the suction pressure is unstable often includes adjusting the fluid level in the wash chamber. For example, the initiated action may include adding fluid to the dishwasher until the measured suction pressure stabilizes. However, it should be appreciated that other actions are also possible.
Notably, by constructing pump inlet assembly 200 as a single, integral piece, assembly is simplified, the number of parts is reduced, and the likelihood of leaks is minimized. Therefore, pump inlet assembly 200 reduces costs while increasing the performance and reliability of dishwasher 100.
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.
