Patent Application
20100108102
1. Field of the Invention
This invention generally relates to a dishwasher having a liquid spraying system for spraying liquid onto utensils to accomplish cleaning.
2. Description of the Related Art
The majority of conventional dishwashers for cleaning utensils, such as silverware, dishes, plates, bowls, glassware, pots, and pans, utilize a liquid sprayer for spraying liquid onto the utensils to remove soils. The sprayer is coupled to a pump or similar means to supply pressurized liquid to the sprayer to produce spray for cleaning the utensils. A wash liquid can be water or water mixed with a detergent, a drying aid, a spot reducer, or any other similar product that facilitates excellent cleaning of the utensils.
The spraying apparatus is commonly a rotating spray arm having multiple nozzles and is driven by the torque produced by two outwardly-directed nozzles on the ends of the spray arm. The nozzles direct a focused stream of wash liquid known as a jet at the utensils to clean and rinse the utensils. As the spray arm rotates, the jets rotate with the arm. This type of spray system relies on moving focused streams of high pressure liquid for cleaning.
A disadvantage of this type of sprayer is that a lot of the cleaning performance relies on the jet impacting the utensil to remove the soils by force. Depending on how the utensils are arranged, it is not always possible for every portion of a utensil to be contacted by the jet. To maintain stable hydraulic operation of the jets, a substantial amount of water is used, which may lead to an undesirable low wash aid concentration during cleaning, which can reduce the cleaning ability of the dishwasher. This leads to another disadvantage in that wash aids, such as detergents, are not always evenly distributed on the dishes as the jets do not directly contact all portions of the utensils. The deflecting and splattering of the liquid off of the utensils can further distribute the wash aid, but this method is hit and miss and highly dependent on the relative positioning of the utensils. Thus, it cannot be relied upon. The jets also produce significant acoustic sound levels due to the forcefulness with which the liquid jets are propelled onto various surfaces in the dishwasher.
In one aspect, the invention is a dishwasher comprising a housing defining a wash chamber, and a liquid spraying system. The liquid spraying system is operable in a first mode to spray a focused stream of liquid within the wash chamber, and operable in a second mode to spray a diffused stream of liquid within the wash chamber.
In another aspect, the invention is a method of washing utensils in a dishwasher comprising a housing defining a wash chamber in which the utensils are received. The method comprises spraying a diffused stream of liquid within the wash chamber, and spraying a focused stream of liquid within the wash chamber.
Referring
Referring to
The pump is located within a sump portion 24 of the bottom wall. In this way, the pump 26 can draw wash liquid collecting in the sump and distribute it through the sprayers into the wash chamber, where it naturally flows back to the sump 24 for recirculation or draining as the case may be.
The pump assembly 26 is designed to pump wash liquid at varying pressures. One way of accomplishing the varying pressures is by operating the pump at different speeds. With such a configuration, it is possible to have either continuously varying pressures or multiple discrete pressures. For purposes of the invention, the pump should generate at least two distinct pressures, regardless of how they are accomplished.
A supply tube 33, extending from the pump, fluidly connects the pump to the sprayers 30 and 32. The supply tube 33 extends generally rearward from the pump assembly 21 to the rear wall 18 of the tub and extends upwardly to supply wash liquid to either of both of the middle spray arm assembly 30 and top spray arm assembly 32. The sprayer 28 is directly connected to the pump 26.
Control valves can control the flow of liquid from the pump to any of the sprayers 28, 30, and 32. The control valves can be selected such that liquid is concurrently or separately delivered to any combination of the sprayers 28, 30, and 32.
With continued reference to
Referring to
The spray arm 38 is an elongated, hollow member defining an interior chamber 39 (
A plurality of openings 42 is disposed about the spray arm 38. The openings extend from an outer surface 43 of the spray arm 38 into the interior chamber and are designed to permit the flow of wash liquid there through. The openings 42 can vary in size and shape so as to modify the flow of wash liquid. Located on each end of the spray arm 38 is a drive opening 45 oriented such that the flow of wash liquid out of the opening 42 will effect the rotation of the spray arm 38.
A nozzle 44 is disposed within the openings 42. The number of nozzles is not critical to the invention, more or less being acceptable. The nozzles 44 fit snugly into the openings 42 so as to create a fluid seal around the nozzle 44 while permitting liquid from the interior of the arm to pass through.
Referring to
The nozzle 44 is preferably formed integrally of a relatively flexible material, as by molding. An exemplary material would be silicone rubber.
The tip 50 includes an horizontal slit 52 and two vertical slits 54 extending from the outside of the nozzle 44 into the interior 50A (
The nozzles 44 in the spray arm 38 of the bottom spray arm assembly 28 can provide at least two distinct spray patterns or modes, which can be controlled by the pressure of the supplied liquid. A first spray mode comprises primarily a focused stream 58, which can be continuous, and is illustrated in
As is typical in a conventional dishwasher, the bottom spray arm assembly 28 is configured to rotate in the wash chamber 20 and spray a flow of wash liquid in a generally upward direction. The spray from the bottom spray arm assembly 28 is typically directed to providing a wash for utensils located in the lower dish rack 34. Like the bottom spray arm assembly 28, the middle spray arm assembly 30 can also be configured to rotate in the dishwasher 10 and spray a flow of wash liquid in a generally upward direction. In this case, the spray from the middle spray arm assembly 30 is directed to utensils in the upper dish rack 36. Typically, the top spray arm assembly 32 directs a spray of wash liquid in a generally downward direction and helps clean utensils on both the lower and upper dish racks 34, 36.
The flexible nature of the nozzles 44 aids in the nozzle 44 assuming different shapes in response to the different liquid pressures. An appropriate high pressure and an appropriate low pressure to produce the focused stream 58 and dispersed stream respectively can be determined by testing, as the specific dimensions and materials used for each nozzle 44 will affect the water pressure required to produce each stream type. It should be noted that the adjectives high and low are used in describing the relative difference between the pressures and is not necessarily a description of the absolute pressure because in the environment of a contemporary dishwasher, both the high and low pressures are generally low pressures in an absolute sense.
To use the nozzle 44 in the first mode, wash liquid is propelled through the liquid spraying system at a higher pressure, and a jet of wash liquid is produced by the nozzle 44. A “jet” of liquid as used in this application is a focused stream 58 of wash liquid that contacts utensils with significant force for removing food remnants. The liquid spray associated with the jet may comprise a focused stream 58 with some associated diffused liquid particles, but the primary character of the liquid spray is that of a focused stream 58. The pressure is great enough that it causes both the horizontal and vertical slits to “crack” open as illustrated in
To use the nozzle 44 in the second mode, wash liquid is propelled through the liquid spraying system at a lower pressure, and a diffused stream of wash liquid is produced by the nozzle 44. A “diffused stream” as used in this application is a dispersed stream of wash liquid. A mist is one example of a diffused stream wherein wash liquid particles are of a size rendering them buoyant in the air within the wash chamber 20. Typically, these wash liquid particles are less than 100 microns in size. The second mode also requires significantly less water to maintain stable hydraulic operation. The lower pressure is great enough to crack the vertical slits, but not great enough to crack the horizontal slit, which results in the nozzle 44 taking on the shape as shown in
One method of utilizing the dual-mode nozzles 44 in the dishwasher 10, is to use the second mode for the distribution of a liquid, such as a detergent solution, on the utensils loaded in the dishwasher 10 to effect a soaking of the soils on the utensils with a detergent solution, and then hit the soaked soils with a focused stream 58 using the second mode. The detergent solution chemically breaks down the soils and the focused stream 58 mechanically removes the soils.
More specifically, as the wash liquid used at the beginning of the wash cycle comprises a detergent wash aid mixed with water, using a diffused stream, such as a mist, more widely distributes the detergent solution than what is obtainable with the traditional focused stream. Advantageously, the greater distribution is accomplished with less liquid than the focused stream. In many cases, the distribution is at a higher concentration because less liquid is used. This wider distribution of a higher concentration of detergent solution improves the removal of the soils from the utensils because more chemistry gets to more of the utensils. The dispensed detergent solution can be permitted to sit and soak into the soils. The minimized amount of water stored in the dishwasher 10 also significantly reduces the overall water requirements, and consequently, the electric energy required for heating the water. Additionally, since the wash liquid particles of the mist are buoyant within the air, the wash liquid is distributed more evenly throughout the wash chamber 20. This further improves the performance of the dishwasher 10, as all utensils in the dishwasher 10 are contacted by sufficient amounts of wash liquid for effective cleaning. The noise produced by the dishwasher is also lessened due to the reduced operating pressure.
Once the detergent has been dispersed throughout the wash chamber 20, and after any soaking period, the dishwasher 10 cleans the utensils using the first cleaning mode. The jets contact the utensils with significant force, which serves to mechanically remove the soils that have been chemically loosened or broken down.
The flexibility of the nozzles serves another purpose, one that is particularly noticeable at this stage during which many food particles are present throughout the dishwasher: the nozzles are self-cleaning. Unlike the rigid nozzles found in conventional dishwashers, any food or debris that enters the nozzle 44 will not become stuck, as the nozzle 44 changes shape each time it is used. Food and debris is therefore inherently removed from the nozzle 44 simply by operating the dishwasher 10.
After the cleaning stage, the dishwasher 10 is again operated in the second mode. The detergent is rinsed off of the utensils using a wash liquid comprising water and, optionally, a drying aid. Using the mist spray for drying purposes is beneficial as it requires less water consumption. Additionally, it has been shown that using a mist spray at this stage produces better drying characteristics. The utensils dry faster because the wash liquid particles are smaller; therefore, the particles require less energy to evaporate compared to larger water droplets associated with a jet spray. The mist spray also produces better wash liquid coverage throughout the dishwasher, further improving drying characteristics by more evenly distributing the drying aid.
The dishwasher 10 and method of washing utensils according to the invention enable superior cleaning of utensils. This is accomplished through the inclusion of flexible nozzles 44 in at least one spray arm 38, which, in combination with the variable speed pump assembly 26, are capable of producing both a focused stream of wash liquid and a dispersed stream of wash liquid. Alternatively, the spray arm 38 could incorporate a combination of traditional nozzles and the nozzles of the invention 44 to produce different spray types at the same time. Similarly, separate spray arm assemblies within the wash chamber 20 could use different types of nozzles to accomplish the same. Separate arm assemblies having different types of nozzles could also be connected to different pump assemblies or different supply tubes to create different spray types at different times, or at the same time. By using the nozzles of the invention 44 along with the variable speed pump 26, not only are food soils and debris removed much more effectively, but resource consumption is reduced as well. Less water is used to clean the utensils, and, accordingly, less electricity is required to heat and pump the water.
While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the invention which is defined in the appended claims.
