Patent Application
20110247666
The present invention is directed to a dishwasher having a pre-conditioning steam cycle in which steam is introduced at selected intervals.
According to U.S. Pat. No. 4,106,517, dishwashers have been offered having dishwasher control systems that utilize a selector switch with individually operated switches controlled manually by pushbuttons, such as “pots and pans”, “normal soil”, “quick wash”, “rinse and hold”, and “rinse and dry”, together with a cancel button. In such systems, the user initiates a cycle by pushing a selected button down beyond a latching position to a momentary position until the machine starts, after which the button is released and the machine automatically finishes the cycle. A Rinse and Hold cycle may be desired if items will be sitting longer than a day in the dishwasher before a full load can accumulate. This minimizes food odor. A version of a Rinse and Hold cycle is a so-called “half-load” cycle. Rinse and hold cycles are often employed to wash lightly soiled items when a quick turnaround is needed.
According to U.S. Pat. No. 7,104,269, the conventional heating element of a dishwasher (located in the recirculating sump) must raise the temperature of not only the 1.5-3.0 gallons of water that is used in a given cycle (equivalent to 12-24 lbs. of water), but also must raise the temperature of the kitchenware to be cleaned, including dishes, pots, pans, silverware and like kitchen utensils (about 20 lbs.), and the cavity/rack/spray-on system of the dishwashing cavity (about another 20 lbs.). The power supply must not only feed the heating element, but also perform the non-heating functions of the dishwasher—e.g., driving the pump that circulates the water under pressure into and around the cavity, driving the controls of the consumer interface, and the like. Furthermore, according to U.S. Pat. No. 7,104,269, separate and apart from the constraint imposed on a US residential dishwasher by the limited power supply available, there is also a constraint on the size or volume of a US residential dishwasher. Both builder-supplied dishwashers (for new home construction) and replacement dishwashers are expected to fit within a given volume of “counter space,” which has become standardized over time to provide a dishwasher cavity of about 7 cubic feet. The standard volume evolved in a way that allowed the dishwasher to fit under a counter at the standard kitchen counter height, with a door at a height at which consumers felt comfortable loading dishes, and a combined height and width that did not take up too much “cupboard” space yet held a reasonable number of dishes. Taking into account the height of the lower tray rollers, the thickness of the door itself, and the space between the bottom of the lower tray and the bottom of the dishwasher cavity leaves approximately 9 inches between the floor and the bottom of the dishwashing cavity. All the working parts of the dishwasher (e.g., inlet water connection, electrical power connection, inlet water valve, motor, valves, hoses, controls, etc.) must fit within this limited height external of the dishwashing cavity.
Thus, there is a need for improvements in dishwashers which enhance the energy saving capability of a dishwasher yet do not compel an expansion of the outer dimension of the dishwasher to a degree that the dishwasher will no longer fit within the existing industry standard for “cupboard space.”
According to one aspect of the present invention, there is provided a dishwasher that performs a pre-conditioning steam cycle. The dishwasher includes a washing compartment for receiving dishware to be subjected to a dishwashing program and a wash water assembly for introducing a selected one of wash water and rinse water into the washing compartment. The wash water assembly is controllable to perform a wash/rinse/dry program and a rinse and hold program. The dishwasher also includes a vapor generator assembly for introducing steam vapor into the washing compartment and a control arrangement for controlling the vapor generator assembly to perform a steam and hold cycle wherein steam vapor is introduced into the washing compartment at selected intervals.
According to a further feature of the one aspect of the present invention, the control arrangement controls the vapor generator assembly to perform a steam and hold cycle in lieu of a rinse and hold cycle.
According to another feature of the one aspect of the present invention, the control arrangement controls the vapor generator assembly to perform a modified rinse and hold cycle in coordination with a steam and hold cycle.
As illustrated in
A spray arm 22 is mounted on the central inlet 20 in a manner such that the spray arm 22 can rotate relative to the central inlet 20 about a vertical axis. A plurality of spray outlets 24 are formed in the top surface of the respective left and right hand wings of the spray arm 22.
A wash pump 26 located below the sump portion 18 includes a wash pump motor serving as a drive motor, an impeller driven by the wash pump motor, and a housing enclosing the impeller. The housing of the wash pump 26 has an inlet port 28 communicated with the base of the sump portion 18 and an outlet port 30 communicated with a lower end of the central inlet 20. The central inlet 20 has an upper opening communicated with the spray arm 22.
A drain pump 32 is located below the sump portion 18. A stock heater 34 is operably connected to the sump portion 18 for heating fluids such as wash solution or rinse solution that is collected in the sump portion 18. A drain conduit 36 extends from the drain pump 32 to a drain take-off location exteriorly of the dishwasher. A water supply valve 38, a drying fan 40, a drying air intake duct 42, and an exhaust duct 44 are all located exteriorly of the dishware handling container 14.
An upper dishware rack 46 is mounted in an upper region of the dishware handling container 14 on a pair of roller track assemblies that permit the upper dishware rack 46 to be selectively withdrawn out of the dishware handling container 14 and retracted into the dishware handling container 14. A lower dishware rack 48 is mounted lower region of the dishware handling container 14 on a pair of roller track assemblies that permit the lower dishware rack 48 to be selectively withdrawn out of the dishware handling container 14 and retracted into the dishware handling container 14. The outside facade housing 12 has a front access opening 50 through which the racks 46, 48 can be extended and retracted. A door 52 is hingedly mounted to the outside facade housing 12 and movable between positions in which it respectively closes off, and permits access to, the opening 50. A control device 54 is mounted in the outside facade housing 12 below the door 52 and is operably connected to a display panel (not shown) on the front of the outside facade housing 12.
The vapor generator 110 includes a boiler 112, a heating element 114, a discharge member 116, a sprayer 118, and a housing 120. The boiler 112 is disposed within the housing 120 of the vapor generator 110. The heating element 114, which may be integral with or positioned inside the boiler 112, is preferably an electrical coil that radiates heat when energized. The electrical coil of the heating element 114 is an electrical resistance heater that heats up in response to the flow of an electrical current therethrough, whereupon the heating element 114, upon reaching a predetermined temperature, vaporizes water in the boiler 112 into a vapor such as steam. The discharge member 116 is provided on the boiler 112 to control the release of the steam or steam/liquid mixture (hereinafter “steam”). The discharge member 116 may be configured as to permit a timed release of steam from the vapor generator 110 or to permit release of steam from the vapor generator 110 in response to a predetermined event. For example, the discharge member 116 can be configured as a one-way biased valve (not shown) having a spring member, a ball member, and a seat. By adjusting the spring constant of the spring member, a pre-determined amount of pressure can be induced within the boiler 112. When this pre-determined pressure is reached, the ball member lifts off the seat and releases the steam. Alternatively, the discharge member 116 may be a bore or passage (not shown) having a predetermined diameter that is selected to induce a predetermined pressure in the boiler 112.
The sprayer 118 sprays fluid in a pre-determined manner (e.g., velocity, spray pattern, volume, duration, degree of aeration) into the dishware handling container 14. The sprayer 118 may be configured to atomize (i.e., create a fine mist), pressurize, disperse the steam vapor or otherwise form a pre-determined flow pattern for the steam vapor. The residential “dwell” time of the steam vapor on the surface of the dishware in the dishware handling container 14 dislodges or otherwise promotes the dislodgement of materials such as contaminants or food particles on the surface of the dishware. This effect may provide a final desired level of cleanliness or some intermediate level of cleanliness.
The vapor generator 110 is also preferably provided with control and sensing features to permit an optimum reliable operation. In this regard, the vapor generator 10 includes safety sensors 122, an interlock 124, a timer 126, and a microprocessor 128. The timer 126 controls the vapor generator 110 operation by, for example, energizing the heating coil 114 for a preset duration. The safety sensors 122 can monitor parameters such as pressure, temperature, electrical flow, moisture and water level. In an advantageous arrangement, the safety sensors 122 are operably coupled to the interlock 124 such that vapor generator 110 operation is interrupted or terminated upon detection of a pre-determined condition. The pre-determined condition can include excessive pressure or temperature, a fluid leak, an electrical short or other event that can compromise the operation of the vapor generator 110 or cause damage or injury. Optionally, the microprocessor 128 can be programmed to cycle the vapor generator 110 through the cleaning operation and to alter operation in the event an undesirable condition is detected.
Upon activation, the heating coil of the heating element 114 boils the water in the boiler 112 to create steam. This steam is brought to a pre-determined condition (e.g., pressure) by the discharge member 116. The steam released from the boiler 112 flows through the sprayer 118. In the event that additional water needs to be supplied, this water is supplied via an inlet 130 leading into the boiler 112.
The operation of dishwasher 10 is as follows. A user loads the dishware, which may be comprised, for example, of plates, saucers, glasses, cups, pots, or pans as well as cutlery such as spoons, forks, and knives, into a selected one, or both, of the upper dishware rack 46 and the lower dishware rack 48. Each respective dishware rack can be withdrawn outwardly of the dishware handling container 14 to facilitate loading of the soiled dishware into the rack and thereafter the rack can be retracted into the dishware handling container 14. The door 52 is moved to its respective position in which it closes off the front access opening 50 once the upper dishware rack 46 and/or the lower dishware rack 48 has been loaded with soiled dishware.
With soiled dishware now loaded into the dishwasher 10, the user can select from one of a range of operating programs to commence or delay the operation of the dishwasher 10. In this regard, the user chooses an operating program for the dishwasher by inputting a program selection via a touchpad 200 on the display panel. The touchpad 200, which is schematically shown in
During the rinse sub-program of the wash/rinse/dry program 204, fresh fill water is introduced into the sump portion 18 and is pumped via the wash pump 26 to be sprayed by the spray arm 22 against the dishware retained in the racks 46, 48, which should now be largely free of food debris. The rinse water drains to the sump portion 18 and can be filtered to remove entrained food debris via a conventional filter arrangement and then recirculated again into contact with the dishware. At the conclusion of the rinse sub-program, the drying fan 40 is operated to direct heated air into the dishware handling container 14 and spent drying is exhausted via the exhaust duct 44.
The touchpad 200 also permits a user to choose other programs in addition to the wash/rinse/dry program 204. For example, the user can select a “rinse and hold” program 206, whereupon, in connection with this program, a predetermined amount of fill water is introduced into the sump portion 18 and ultimately sprayed via the spray arm 22 into the dishware handling compartment 14 to effect wetting of the soiled dishware. This introduced amount of fill water in the “rinse and hold” program 206 is a lesser amount than the water introduced during the wash sub-program of the wash/rinse/dry program 204 and the purpose of the water introduced in the “rinse and hold” 206 is to effect wetting of the soiled dishware to prevent food debris on the dishware from “caking” or sticking in a tenacious manner to the surface of the dishware for a period of time between the loading of the soiled dishware into the dishwasher 10 and a later time, which may be several hours later, at which awash/rinse/dry program 204 is initially commenced.
The touchpad 200 also offers the possibility for the user to select a “steam and hold” program 208 in lieu of, for example, either the wash/rinse/dry cycle 204 or the “rinse and hold” program 206. The steam and hold program 208 is a program that introduces steam into the dishware handling container 14 in a predetermined manner to accomplish the same objective as the “rinse and hold” program 206—namely, to accomplish the objective of wetting the soiled dishware to a degree that inhibits the “caking” or tenacious sticking of food debris to the surface of the dishware until a wash/rinse/dry program 204 is ultimately performed. The steam and hold program 208 advantageously offers the benefit that a fair amount of water can be conserved in contrast to the water introduced during the rinse and hold program 206 and, moreover, offers the benefit of energy savings in that the energy required to generate steam for the steam and hold program 208 can, in many circumstances, lead to an ultimate energy savings in that less heat energy is needed during the subsequent wash/rinse/dry program 204.
Upon selection of the steam and hold program 208, the control interface 202 controls the vapor generator 110 to cause energization of the heating element 114 within the boiler 112. This energization of the element 114 results in a heating up of water in the boiler 112 to a degree that water is vaporized into steam in a completely gaseous form or in a gas/liquid form, both forms being collectively referred to as “steam vapor.” The steam vapor is released by the discharge member 116 into the dishware handling compartment 114 and the steam vapor contacts the food debris on the soiled dishware and promotes dislodgement of the food debris from the surface of the dishware. The contact of the steam vapor with the food debris and the surfaces of the dishware, as well as the surfaces on the interior of the dishware handling compartment 14, causes condensation of the steam vapor and the resulting condensed water droplets ultimately flow downwardly and are collected within the sump portion 18.
The cyclic frequency at which steam vapor is introduced by the discharge member 116 into the dishware handling compartment 14 can be configured according to a pre-selected frequency or, alternatively, in response to a real-time evaluated condition. With respect to introducing steam vapor in accordance with a pre-selected frequency, steam vapor may be introduced, for example, every 30 minutes until a maximum pre-set number of steam introductions had been performed or, alternatively, until a wash/rinse.dry program 204 has commenced operation. Thus, a total of eight introductions of steam vapor may be performed within a four hour period with such steam vapor being introduced during each 30 minute interval and thereafter no additional steam vapor being introduced. It can thus be understood that, for example, during an overnight period of several hours, the introduction of steam vapor according to the just-described steam vapor introduction frequency will beneficially result in a continuous level of moisture or a cyclically refreshed level of moisture in the dishware handing compartment 14 that beneficially at least largely inhibits the “caking” or tenacious sticking of food debris to the surfaces of the dishware and optimally contributes to a detachment of food debris from dishware before another dishwasher operation has commenced.
A plurality of pre-set steam vapor frequency programs can be stored, for example, in a frequency program 210 that can be accessed when the steam and hold 208 is selected, with the user having the capability to select a given one of the pre-set steam vapor frequencies via the touchpad 200. Alternatively, the steam and hold program 208 can be controlled via the inputs provided through the touchpad 200 to perform introduction of steam vapor in response to a real-time condition. As seen in
The control arrangement 202 also controls a hybrid program 214 that permits both the benefits of a “rinse and hold” program and of a “steam and hold” program to be obtained. The hybrid program 214 causes an introduction of water from the sump portion 18 in the same quantity and manner as the water distribution step performed during the rinse and hold program 206 and causes, as well, an introduction of steam vapor from the vapor generator 110. Thus, soiled dishware in the dishware handling compartment 14 can be subjected to both a completely liquid spray from the spray arm 22 during a rinse and hold step and subjected to steam vapor from the vapor generator 110 during a steam and hold step and this hybrid or combined treatment can beneficially result in enhanced removal of food debris from soiled dishware. It can be appreciated that the steam and hold program 208 and the hybrid program 214 can result in an ultimate water and energy saving process as compared to a conventional process.
While a particular embodiment of this invention has been shown and described in connection with a dishwasher having a pre-conditioning steam cycle in which steam is introduced at selected intervals, this is by way of illustration only and does not constitute any sort of limitation since there are various alterations, changes, deviations, amendments, revisions, eliminations, additions, substitutions, omissions and departures which may be made in the present illustration and other types of arrangements with which the present invention can be used without departing from the scope of this invention as defined only by a proper interpretation of the appended claims.
