Patent Application
20120312337
The present invention relates generally to dishwashers, and more particularly to a system for backflushing filters in the dishwasher.
Conventional dishwashers include a main pump and fluid distribution system for circulating wash fluid within the wash chamber via spray arm assemblies or jets. A drain pump and associated drain system are used to drain the wash fluid from the chamber at the appropriate time in the wash cycle. The wash fluid sprayed onto the dishwasher items is collected in a sump located in a lower portion of the wash chamber, and water entering the sump is filtered through one or more pre-pump filters to remove soil and sediment from the washing fluid. In certain dishwashers, one of these filters may be a fine filter system in flow communication with the main pump assembly to remove soil and sediment of a smaller size than those filtered by an upstream coarse filter. The main pump assembly draws wash fluid from the sump to recirculate in the wash chamber, and the coarse and fine filters are used to continuously filter the water in the sump during the re-circulation process.
It is an inherent tendency of the filters to accumulate relatively large amounts of foreign matter over time, particularly at the point at which the water path through the fluid distribution system is of least resistance. This location generally corresponds to the section of the filter directly in line with main pump. Removal of this matter is necessary to ensure proper flow of the wash fluid through the system. Certain prior art systems rely on flushing of the filters with wash fluid that is redirected from the spray arm assemblies or dedicated jets. These systems are relatively complicated and have other inherent drawbacks.
Accordingly, other system designs for flushing filters in a dishwasher in a cost-effective and relatively simple manner would be welcome.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
According to certain aspects of the present disclosure, a dishwasher includes a wash chamber and a sump disposed below the wash chamber, wherein wash fluid supplied to the wash chamber collects in the sump. A main pump is configured to drawn wash fluid from the sump and recirculate the wash fluid back into the wash chamber, for example through one or more spray arm assemblies. One or more filters are operably disposed in the fluid distribution system to filter the wash fluid recirculated by the main pump. A backflush line is provided and has an outlet disposed at the downstream side of the filter. A backflush pump is configured to supply backflush fluid through the backflush line against the filter. A reservoir that is separate from the sump and sized to hold a measured amount of fluid is in communication with the backflush pump, wherein at a defined time, the pump draws backflush fluid from the reservoir and directs the fluid against the backside of the filter to flush particulates from the filter.
In a particular embodiment, the reservoir is filled with fresh water from a main fill line that is used to initially supply wash fluid to the wash chamber in a fill mode of the wash cycle. This may be accomplished in various ways. For example, in one embodiment, a main water valve in the main fill line is actuated to supply the initial wash fluid in the fill mode. The reservoir may be supplied with fresh water by a supply line that is in communication with the main fill line downstream of the main water valve such that the reservoir is supplied with water during each fill mode. In an alternate embodiment, the supply line may be in communication with the main fill line upstream of the main water valve, wherein an independently actuated isolation valve may be disposed in the supply line. With this embodiment, the reservoir can be filled independently of filling the wash chamber by actuation of the isolation valve for a defined time.
Particular embodiments may include a level sensor configured with the reservoir, wherein the reservoir is refilled upon the sensor reading a low water level condition. The sensor may be in communication with the isolation valve discussed above, wherein the isolation valve is automatically actuated to supply fresh water to the reservoir in response to a water level signal from the sensor.
In still a further embodiment, a main fill line supplies the initial wash fluid for the wash chamber by first filling the reservoir, which has an overflow outlet in fluid communication with the wash chamber. Thus, the wash chamber is filled with overflow after the reservoir has been filled, with the overflow outlet provided at a height in the reservoir to ensure a desired amount of fresh water in the reservoir for one or more flush sequences.
It is not necessary that the reservoir be filled with fresh water in all embodiments. For example, in a particular embodiment, the reservoir may include a receiving end that is in fluid communication with the wash chamber, wherein the reservoir is filled with wash fluid recirculated within the wash chamber by the main pump. With this embodiment, the receiving end of the reservoir may include a receiver structure configured in a wall (e.g. back wall, side wall, or front door panel) of the wash chamber at a location and orientation to “catch” wash fluid supplied into the wash chamber, for example by one or more of the spray arm assemblies.
In certain embodiments, the filter may be disposed upstream of the main pump (e.g., a pre-pump filter) such that particulates backflushed from the filter are directed to the sump during a backflush sequence of the wash cycle. In another embodiment, the filter may be disposed downstream of the main pump such that particulates backflushed from the filter are directed back through the main pump to a drain line or header during the backflush sequence. The dishwasher may include multiple filters, with each respective filter having a backflush line configured therewith.
In particular embodiments, the backflush pump may be a dedicated pump used strictly for filter flushing operations. In other embodiments, one of the other existing pumps, such as a drain pump or main circulation pump, may be configured with the appropriate lines and valves to also function as the backflush pump during the filter flushing sequence.
The present invention also encompasses various method embodiments for backflushing a filter in a dishwasher in accordance with various aspects discussed above.
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.
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 so as to rotate in relatively close proximity to the lower rack 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 arm assembly (not shown) may be located above the upper rack 130.
The lower and mid-level spray-arm assemblies 144, 148 and the upper spray arm assembly are fed by a fluid circulation assembly for circulating water and dishwasher fluid in the tub 104. The fluid circulation assembly may be located in a machinery compartment 140 located a bottom sump portion 142 of the tub 104, as generally recognized in the art. Each spray-arm assembly includes an arrangement of discharge ports or orifices for directing washing liquid onto dishes or other articles located in the upper and lower racks 130, 132, respectively. The arrangement of the discharge ports in at least the lower spray-arm assembly 144 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 a memory and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with a cleaning cycle.
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 of door 120 as shown. 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 122 of door 120. Typically, the controller 137 includes a user interface panel 136 through which a user may select various operational features and modes and monitor progress of the dishwasher 100. The user interface 136 may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface 136 may be in communication with the controller 137 via one or more signal lines or shared communication busses.
It should be appreciated that the invention is not limited to any particular style, model, or other configuration of dishwasher, and that the embodiment depicted in
As wash liquid is pumped through the lower spray arm assembly 144, and further delivered to the mid-level spray arm assembly 148 (
In one embodiment, a drain valve 186 is established in flow communication with the sump 150 and opens or closes flow communication between the sump 150 and a drain pump inlet line 188. The drain pump assembly 174 may include an electric motor for pumping fluid from the inlet line 188 to an external drain system via drain 173. In one embodiment, when the drain pump is energized, a negative pressure is created in the drain pump inlet line 188 and the drain valve 186 is opened, allowing fluid in the sump 150 to flow into the inlet line 188 and be discharged from the fluid circulation assembly 170 via the external drain 173.
Referring to
Embodiments of a dishwasher 100 in accordance with aspects of the invention include one or more filters in the fluid circulation assembly 170. The invention is not limited to any particular number of filters, type of filter, and so forth. In the embodiment depicted in
It should be appreciated that the invention is not limited to any particular type of filter 210, 212 within the fluid circulation system 170. Conventional filters are well known in this regard, and any one or combination of such filters may be utilized with the present invention. For example, the filters 210, 212 may be removable filters that are seated within the lines or piping of the circulation assembly 170. The filters may have a conical shape, or a flat plate-like shape, and so forth.
Referring again to
A backflush pump 234 is configured with the backflush line 216 and supplies backflush fluid through the line 216 against the filters. In the depicted embodiment, the backflush pump 234 is a separate dedicated pump for this purpose. It should be appreciated, however, that the invention is not limited to a dedicated pump 234. For example, either of the other pumps 172, 174 may be operably configured to also function as a backflush pump with appropriate connections, isolation valves, and so forth.
A reservoir 220 that is separate from the sump 150 is configured with the backflush pump to provide a supply of backflush fluid to the pump. The reservoir 220 may have any suitable configuration and be located at any convenient location within the dishwasher 100. For example, the reservoir 220 in the embodiment of
In certain embodiments, the reservoir 220 is filled with fresh water that has not been previously recycled in the wash chamber 106. This fresh water may be supplied with the initial filling of the wash chamber 106. For instance, as depicted in
In the embodiment of
In the embodiment of
In the embodiment depicted in
As mentioned, the invention is not limited by the location of the filters 210, 212. In the embodiment of
The present invention also encompasses various method embodiments for backflushing a filter or filters in a dishwasher in accordance with aspects discussed above. For example, one embodiment of such a method includes collecting backflush fluid in a reservoir 220 that is separate from a sump 150 in a dishwasher 100. During a backflush sequence, fluid is drawn from the reservoir 220 with a pump and directed against a downstream side of the filter 210, 212. The pump may be a dedicated backflush pump 234.
The method may include filling the reservoir 220 with fresh water that has not been re-circulated as wash fluid within the wash chamber 106. In another embodiment, the method includes filling the reservoir with wash fluid that has been re-circulated in the wash chamber 106.
The method may also include sensing the level of backflush fluid within the reservoir 220 and re-filling reservoir upon the level reaching a low set point.
In still another embodiment, the method may include initially filling the reservoir 220 in a fill mode with fresh water until the reservoir is filled to an overflow outlet that is in communication with a wash chamber, wherein continued filling of the reservoir results in overflow of fresh water into the wash chamber from the reservoir.
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.
