US 3272652 A
Description (OCR text may contain errors)
Sept. 13, 1966 D. c. WOOD METHOD OF REMOVING FILM DEPOSITS Original Filed Jan. 6, 1961 INVENTOR.
BY ja m www, v /w United States Patent 3,272,652 METHOD OF REMOVING FILM DEPOSITS Donald C. Wood, Fredonia, Wis., assignor to Whirlpool Corporation, a corporation of Delaware Original application Jan. 6, 1961, Ser. No. 81,083.
Divided and this application Nov. 12, 1964, Ser.
4 Claims. (Cl. 134-34) This application is a division of my copending application Ser. No. 81,083, filed Jan. 6, 1961, now abandoned.
This invention relates to dishawashers and in particular to a method of removing film deposits from the washed objects.
A serious problem in the use of automatic dishwashers is the development of a cloudy film on glassware, dishes and the like as a result of washing such articles a number of times in hard water. This film appears to comprise a calcium or magnesium complex, the deposit of which may be accelerated by washing such articles as in detergents containing phosphates or silicates.
The present invention is concerned with the removal of this film from the glassware and comprehends the removal thereof by contacting the glassware with a fluid containing monovalent electropositive ions.
A principal feature of the invention is, therefore, the provision of a new and improved method of removing film deposits on elements such as glassware resulting from the washing thereof.
Another feature of the invention is the provision of such a method of removing film deposits including the steps of providing a solution containing monovalent electropositive metal ions and contacting said solution with said deposits on the elements.
A further feature of the invention is the provision of such a method of removing film deposits wherein the solution comprises a brine solution.
Still another feature of the invention is the provision of such a method of removing film deposits wherein the solution is formed substantially concurrently with the contacting thereof with said film deposits.
Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:
The figure is an isometric left rear view of a dishwashing apparatus provided with means embodying the invention for removing film deposits from elements such as glassware.
In the exemplary embodiment of the invention, as disclosed in the drawing, a dishwasher generally designated of generally conventional construction includes a cabinet portion 11 in which elements such as dishes and glassware may be washed. Access to the interior of the cabinet for insertion and removal of the dishes and glassware may be had by means of a conventional cover 12 secured to the cabinet by suitable hinge structures 13. Washing water is delivered to the interior of the cabinet by suitable conventional means such as a control valve 14 connected to a conduit 15 which is, in turn, connected to a suitable supply of hot water (not shown). Valve 14 may comprise a conventional solenoid operated valve which, when opened, passes the hot water through a discharge conduit 16 to an inlet means 17 for delivering the water to the interior of the cabinet through a suitable spray device 18 therein. The wash water is recirculated within the cabinet by suitable conventional means including a drain 19 and a pump 20. Suitable control means including a timer (not shown) may be associated with the valve 14 to effect an automatic operation of the dishwasher as desired.
The present invention comprehends the provision of means for introducing into the dishwasher or generating 3,272,652 Patented Sept. 13, 1966 therein a fluid adapted to remove film deposits on glassware and the like resulting from the washing thereof. If has been found that these deposits which produce a cloudy, unsightly film on the glassware are caused primarily by orthosilicates and/or orthophosphates in the washing solutions in hard water. These deposits may be removed by placing the glassware in a solution containing monovalent electropositive ions for a substantial period of time whereby the glassware is restored to sparkling clarity. As shown in the drawing, the contacting of such a fluid with the glassware may be eflected in dishwasher 10 by providing a selector valve 21 in the conduit 16 selectively operable to direct the incoming water through a bypass conduit 22 leading toa container 23 in which a suitable quantity, such as two pounds, of salt per each 20 pounds of Water is placed. A discharge conduit 24 leads from the container 23 to the inlet means 17 whereby water delivered through conduit 22 and passed through the container 23 to form a salt solution is delivered through the conduit 24 and inlet means 17 to the interior of the dishwasher to be sprayed and circulated therein similar to the washing water. The spraying and circulation of the salt solution may be controlled by a suitable timer control 25 so that this operation is continued for a predetermined period of time such as 1 /2 hours to assure that the film deposit on the glassware is fully removed. The time necessary to fully remove the deposit has been found to vary with the amount of deposit on the glassware and the strength of the salt solution and, thus, timer 25 may be provided with suitable adjusting means 26 for varying the length of the cycle. In the conventional dishwasher, a quantity of approximately two pounds of salt provides an approximate 10% salt solution; satisfactory film removal may be effected with substantially less salt such as a quantity providing as low as approximately 3% solution. Where a mini mum treatment time is desired, the solution may be a saturated solution. The customary spray action of the dishwasher accelerates the ion exchange to remove the deposit in a relatively short time.
The removal of the film deposits from the glassware may be effected relatively infrequently, depending on the rate of deposit of the film. Thus, control 25 may be provided with a manually operable push button 27 for effecting the film removing operation only when desired. Thus, selector valve 21 may be normally maintained in the position wherein flow of the water from valve 14 is through conduit 16. Upon operation of the control 25 to initiate the film removing cycle, the control may actuate the valve 21 to direct the water to conduit 22 rather than conduit 16. The control may be arranged so that upon completion of the control cycle the valve 21 is restored to the normal position for directing the water from the valve 14 to conduit 16 allowing normal dishwashing operation until the operator once again desired to effect a film removing operation.
The salt which may be used for removing the film deposits may comprise any salt providing monovalent electropositive ions such as metal or hydrogen ions. Illustratively, sodium chloride may be utilized. To flush the dishwasher and rinse the glassware subsequent to the film removing operation, the control 25 may be arranged to provide an additional rinse cycle.
If desired, the salt may be dispensed directly into the dishwasher from a dispenser such as the well known types for dispensing detergent but of increased size to accommodate the amount of salt required.
This invention may be practiced either periodically as described or more frequently as, for example, in each cycle of dishwashing. By adding a brine and rinse operation to an otherwise conventional dishwashing cycle following its wash and rinse operations, the objectionable deposits may be effectively prevented from building up on the articles.
Having described my invention as related to the emmodiment shown in the accompanying drawing, it is my intention that the invention be not limited by any of the details of description, unless otherwise specified, but rather be construed broadly within its spirit and scope as set out in the accompanying claims.
The embodiment of the invention in which an exclusive property or privilege is claimed is defined as follows:
1. The method of removing film on tableware deposited thereon as a result of washing the tableware with phosphate or silicate containing detergents in hard water, comprising the steps of:
forcibly spraying the tableware with a solution of hard water and at least approximately 3% by weight sodium chloride to dissolve the deposited film; and
rinsing the tableware with water to remove said solution and dissolved film.
2. The method of claim 1 wherein the water utilized in each of the film removing and rinsing steps is provided from a common source.
3. The method of claim 1 wherein said film removing solution is a saturated solution.
4 4. The method of claim 1 wherein the spraying and rinsing steps are conducted within a chamber and wherein the sodium chloride is introduced into the chamber for dissolving in hard water therein to form said film removing solution.
References Cited by the Examiner UNITED STATES PATENTS 1,870,318 8/1932 Stoddard 13429 2,008,839 7/1935 Samson 134-22 2,395,260 2/1946 Farmer et a1 13422 X 2,424,049 7/1947 Parker et a1 l3428 X 2,766,151 10/1956 Stearns 134-27 2,825,666 3/1958 Stoddard 13428 2,884,349 4/1959 Axelrad 134-22 FOREIGN PATENTS 118,498 5/1944 Australia. 647,673 12/ 1950 Great Britain.
MORRIS O. WOLK, Primary Examiner.
J. ZATARGA, Assistant Examiner.