US 3094245 A
Description (OCR text may contain errors)
June 18, 1963 MIZUNO 3,094,245
LIQUID DISPENSER Filed May 2. 1960 FIG.4
INVENTOR. KEICHI M IZUNO ATTORNE S United States Patent Oflice 3,094,245 Patented June 18, 1963 3,094,245 LIQUID DISPENSER Keichi Mizuno, White Bear, Minn., assignor to Economics Laboratory, Inc., St. Paul, Minn., a corporation of Delaware Filed May 2, 1960, Ser. No. 26,144 8 Claims. (Cl. 222-43) dispenses a volume of liquid from a supply container in response to rise in ambient temperature.
The liquid-dispensing apparatus of this invention, al-
though having no moving operative parts, includes manually adjustable means by which different volumes of liquid can be automatically dispensed from a supply container repetitively in response to cyclic increases in ambient temperatures. Such apparatus is particularly well suited for use in environments which, during the normal course of operation, undergo cyclic temperature variations; for example, in automatic dish-washing machines.
The apparatus of the present invention has been found to be particularly useful for automatically dispensing a sufficient volume of rinse-fluid or wetting agent in domestic types of automatic dishwashers during the final rinsing operation. The exact volume is not critical, although it must be at least in the final rinse.
In commercial and in some domestic dish-washing machines, the dishes are washed with detergent-carrying water at a temperature in the neighborhood of 140 Fahrenheit. In commercial dish-Washers, rinsing is customarily effected by spraying the dishes with fresh water at a temperature higher than that of the wash water, usually in the neighborhood of 170 to 190 Fahrenheit. However,
these temperatures are seldom if ever reached in domestainer having an opening at the top. The container is partially filled with the liquid to be dispensed, and a tubular delivery element is mounted in the container opening so that the lower extremity of the element is submerged well below the surface of the contained liquid. The clearance between the delivery element and the container opening is air-sealed so that the only exit path for the contained liquid is via the opening in the tubular element. In accordance with the invention, a given volume of liquid is expelled upwardly through the. delivery tube when the contained air and liquid are subjected to a given increase in temperature. The volume per unit of time of liquid dispensed through the upper opening in the tubular element varies primarily as a function of the resultant air pressure and inversely as a function of the passage volume of the delivery tube. In accordance with one aspect of the invention a flow adjustment rod is mounted inside the delivery tube to form a variable volume passage.
Means are provided for retaining the rod at different manually adjustable longitudinal positions within the delivery tube in order to alter the total volume of the delivery tube. When the adjustment rod is confined entirely within the delivery tube a maximum volume of liquid is expelled through the passageway for a given change in temperature of the container and its contents. As the rod is progressively withdrawn from the tube, less and less liquid is expelled out the top of the tube for a given temperature change, since the total volume of liquid required to fill the tube is accordingly increased.
The apparatus of the present invention features the advantages of having high operational reliability, very low manufacturing cost, low maintenance requirements and long operating life.
For explanatory purposes, a preferred embodiment of the invention is shown in the accompanying drawing and is described below in connection with the dispensing of a wetting agent in a dishwashing machine. It is to be understood, however, that the apparatus of the present invention is not limited in its use to this specific application.
In the drawing:
FIG. 1 is an elevational view of a preferred embodiment of the invention;
FIG. 2 is a partial sectional view of the embodiment of FIG. 1 showing the various operational and structural features of the invention;
FIG. 3 is a top or plan view of the embodiment shown in FIG. 1; and
FIG. 4 is a cross-sectional view taken along the line 44 of FIG. 1, showing a metal wick which comprises a part of the invention.
Referring to FIG. 1, there is shown generally an assembled automatic liquid dispenser provided by the invention. A calibrated cylindrical container 10-, advantageously made of transparent material such as heat-resistant glass, is provided for storing a desired volume of liquid to be dispensed. The container is provided with a top opening which is adapted to be partially covered by an integral cap and dispenser assembly 11. The integral assembly I l includes a lower threaded cap 12 adapted to engage with external threads around the outer periphery of the cylindrical container or bottle 10, a cylindrical dispensing tube 13 which extends through the cap into the container (see FIG. 2), an upper dispensing bowllike reservoir 14 and a mounting clip 15-. A flow adjustment rod 16 is mounted inside the liquid dispensing tube- Rod 16 and assembly 11 are advantageously molded from a slightly flexible plastic material which can withstand temperatures up to at least 200 F., without appreciable softening or expansion and which at the same time resists chemical reaction with the Wetting agent and detergents. Plastic materials such as chlorinated polyether and polypropylene have been used satisfactorily for dispensing the commercial wetting agent Rinse Dry which is a very low sudsing, nonionic surface active material. For use in this dispenser, the Wetting agent should not contain a highly volatile solvent. Rather heavy, heatresistant glass is suitable for the liquid container because, among other characteristics, it conducts heat rather slowly.
The normal operation of the liquid dispenser is best explained by reference to FIG. 2. Assembly 11 is unscrewed from the container, and a supply of wetting agent 17 is poured into the container until the liquid rises to the indicated Line A. Rod 16 is adjusted vertically in the bore of the delivery tube so that it is retained at position 3, as shown, by detents to be described below.
The cap assembly is then screwed on the container with the lower portion of the delivery tube submerged in the liquid, as shown. A soft gasket 20 is provided to effect an air-tight seal between the assembly and the container. submersion of the delivery tube in the liquid causes the liquid to rise by displacement to a level above the indicated line 1. Air is entrapped above the liquid at the surrounding temperature and atmospheric pressure, and when the temperature of'the container and the entrapped air is elevated, the pressure of the air is increased in accordance with well-known laws of'physics. An increase in the internal air pressure causes liquid to rise upwardly through the annular passage 18 between the dispensing tube inner-wall surface and the outer surface of rod 16. When the pressure is sufiiciently high, liquid will flow into the upper reservoir 14. The volume of liquid which is displaced from the container into the reservoir, in response to a given temperature change during a given time period and for a given column height, varies with the total effective volumetric capacity of the dispensing tube. Rod 16 is provided for determining and controlling the total effective or average-volumetric capacity of the dispensing tube and hence functions effectively as a means for adjusting the volume of liquid which is dispensed to the upper reservoir for a given temperature change over a given time. Thus a maximum volume will be dispensed by the apparatus when the rod is located at position 1 entirely within the tube. Lesser volumes are accordingly dispensed when the rod is adjusted upwardly, with a minimum volume being dispensed at position 10.
In a practical working model of a wetting agent dispenser for a dishwasher, the container is [advantageously made sufficiently large to contain an adequate supply (of the order of /2 oz.) of wetting agent for, say, a dozen washing operations. This is the capacity of the container in the drawing. The loaded dispenser, at substantially room temperature, is suspended by clip :15 from a convenient internal rack member 21 of the washing basket, in a generally vertical position as shown. During the washing cycle the wash water temperature will not be sufficiently high to dispense appreciable wetting agent into the reservoir, because of the time required to heat the container and its contents. However, by the beginning of the final rinse cycle the temperature within the container will have increased, due to the higher temperature of the rinse water or to the elapse of time, or both. As a result, the internal pressure will rise sufiiciently to dispense wetting agent from the container into the reservoir. Since the reservoir is exposed to the spray of rinse water in the machine, the wetting agent is promptly washed out of the reservoir and thoroughly dispersed with the rinsing water.
Action of wetting agents for eliminating water spots by reducing the surface tension of the rinse water is well known and will not be further discussed herein. Use of about 0.5 milliliter of one type of concentrated wetting agent per five to nine quarts of rinse water has been found to afford satisfactory results, although different amounts of other wetting agents may be required. In an initial installation the operator can adjust the amount of wetting agent dispensed with sufiicient accuracy by comparing the container levels with the corresponding numbered calibration rnarks after successive washing operations. Thus, if the liquid level tends to run above or below the numbered calibration lines after a corresponding number of operations, the rod should accordingly be moved downwardly or upwardly one position at a time to increase or decrease the volume dispensed until a more accurate adjustment is achieved. When the liquid level drops to Dine B the container should be refilled.
Usually the temperature in the machine reaches a maximum during the drying cycle; so, during the drying cycle the wetting agent will continue to rise into the reservoir which, therefore, should be large enough to hold it without overflowing.
After the rinsing and drying operations have been completed, the temperature of the washer drops back to room temperature, and the internal air pressure in the dispenser accordingly drops. The reduced pressure resulting trom the temperature drop creates a partial vacuum which acts to suck down into the container any residual water or wetting agent, or both, left in the reservoir along with sufficient air to restore the internal air pressure to substantially atmospheric pressure. This breathing action restores the dispenser to the initial operating condition and hence readies it for the next [dispensing operation.
In order to minimize undesired dilution of the stored wetting agent by the return into the container of water collected in the reservoir after the temperature has dropped, a wick 25 is provided having one end embedded in the wall of the plastic reservoir bowl and the other end extending freely outside the edge of the bowl. The wick functions during the entire drying operation (following the last rinse cycle) to siphon off collected water from the resorvoi-r and deposit it drop by drop into the machine. The wick is advantageously made from stainless steel wire mesh material (=l00 mesh) which is folded into several layers (see enlarged sectional view in FIG. 4 showing four layers) to increase the flow rate and to provide the necessary mechanical rigidity for self-support. Since the density of the wetting agent is greater than that of water, and only slightly, or slowly, soluble in hot water, any wetting agent present in the reservoir will settle to the bottom and therefore be little affected by the wick. Furthermore, the viscosity of the wetting agent is higher than that of water and hence very little of the wetting agent will be carried out of the bowl by the wick. Other wetting agents might require wicks of different mesh sizes.
The top or plan view of FIG. 3 shows a detent and guide arrangement for retaining the adjusting rod in coaxial alignment with the dispensing tube at selected vertical positions. Three fixed-position detent members 26 extending from the inner wall of the dispensing tube 13 are provided to engage the spaced circular grooves 27 on rod 16 and retain the rod at any preselected vertical position. Three relatively long guide members 28 are also provided on the inside wall of the dispensing tube. These members hold the rod centrally spaced with respect to the inner wall surface of the surrounding tube. The guide members and detent members are stagger-spaced around the upper portion of the delivery tube immediately below the entrance hole in the reservoir. The spacings between the six members permit flow of the wetting agent liquid between the tube and the reservoir.
Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art, that various changes and modifications can be made without departing from the spirit and scope of the invention. For example, in certain applications the user may find it advantageous to omit the reservoir or wick. Also, other means may be employed to retain the rod at its various adjustable positions. Accordingly it will be understood that the foregoing description is given by way of example and not by way of limitation, (and that the invention is not limited in scope or application to the single preferred form described herein.
1. Apparatus for dispensing a volume of liquid in response to a rise in ambient temperature, comprising a supply container adapted to be partially filled with a liquid to be dispensed and the space above said liquid filled with air, said container having an open reservoir at the top, a tubular dispensing element extending from the bottom of said reservoir downwardly in sealed engagement with the container and terminating within said container beneath the surface of the liquid, a volume-flow adjustment rod mounted within and spaced from said tubular element to define therewith a constricted passage therebetween for dispensing said liquid, and means for retaining said rod at different longitudinal positions relative to said tubular element to vary the length of said passage within said tubular dispensing element.
2. A device for dispensing liquids in response to increase in ambient temperature, comprising a container adapted to be partially filled with the liquid to be dispensed and partially filled with air above the liquid, an elongated element passing through and scalable in the top of the container and having a bore therethrough extending from beneath the minimum level of said liquid upwardly through the container to the atmosphere, a volume-flow adjustment rod fitted within said bore and spaced therefrom to define a constricted passage therebetween, and means for adjusting the length of rod within said bore to vary the volumetric capacity of said passage, whereby increasing ambient temperature expands the air content of the container and forces a portion of said liquid upward through said passage and .out the top thereof, the volume of said liquid dispensed being a function of the longitudinal position of said rod in said bore per unit of temperature rise per unit of time.
3. A device for dispensing a liquid in a dishwashing machine or the like, in response to increase in ambient temperature therein, including a bottle sealed except for an open top, and a liquid dispensing element sealable in the top of the bottle, comprising a tubular member having an inside bore and which extends upwardly from a level near the inside bottom of the bottle to a level outside and above the bottle, an open reservoir in which the upper end of said tubular member terminates such that liquid can flow upwardly from said bore into said reservoir, a rod within said bore and spaced from the wall thereof to define a constricted passage between said' rod and said tubular member, and means for retaining said rod at predetermined longitudinal positions within said bore to adjust the volume of liquid dispensed in response to increase in temperature for a given time.
4. A device according to claim 3 in which said retaining means comprises detent means on the inside wall of said tubular member, and depressions on the surface of said rod which are disposed to register with and complement the detent means, said rod being longitudinally movable within said bore.
5. A device according to claim 4 in which said bottle includes a vertical wall, a plurality of calibration marks on said wall spaced apart vertically, the spacing between successive marks being measured to correspond approximately to the various predetermined levels of liquid at corresponding successive rinsing operations of said machine, and the depressions on said rod being longitudinally spaced apart by distances required to adjust the liquid flow per rinse cycle to correspond to the calibration marks on said bottle.
6. A device according to claim 4 in which said depressions comprise a series of parallel grooves spaced apart along said rod, and said detent means comprise a plurality of small projections symmetrically disposed around the inside of said bore near the upper end thereof so as also to form a plurality of symmetrical channels within said constricted passage.
7. A device for dispensing a liquid in response to increase in ambient temperature, including a bottle sealed except for an open top, and a liquid-dispensing element sealable in the top of the bottle, comprising a vertical tubular member having an inside bore and which extends upwardly from a level near the inside bottom of the bottle to a level outside and above the bottle, a reservoir in which the upper end of said tubular member terminates such that liquid can flow under pressure from said bore into said reservoir, and a rod within said bore spaced from the wall thereof to define a constricted passage between said rod and said tubular member, said tubular member having first retaining means and said rod having a plurality of second retaining means longitudinally spaced along said rod, said first and second retaining means being complementary and cooperating to secure said rod at any of a plurality of predetermined longitudinal posit-ions within said bore to adjust the volume of liquid dispensed per unit of temperature change per unit of time.
8. A device for dispensing rinse fluid in the rinse Water of a dishwashing machine, wherein said fluid is of density greater than that of water, which includes a container closed except for an opening at the top, a fluid-dispensing element comprising a tubular member having a central bore and extending from a level within the container near the bottom thereof upwards through said opening to a level above the top of said container, detachable means sealing the tubular element to said container, an open fluid-receiving reservoir cup disposed on the upper end of said element so that said bore opens into the bottom of said reservoir, said reservoir cup being of capacity suflicient to retain at least as much rinse fluid as will tend to flow therein during the drying cycle of said machine, a wick extending into said reservoir, over the rim of said cup and down the outside thereof, said wick being of material adapted to conduct water by capillary action and comparatively not to conduct rinse fluid of density greater than water, and means for adjusting the volume flow of fluid from said -b ore into said reservoir.
References Cited in the file of this patent UNITED STATES PATENTS 398,528 Molin Feb. 26, 1889 709,638 Johnson Sept. 23, 1902 903,196 Johnson Nov. 10, 1908 1,223,120 Stohn et a1. Apr. 17, 1917 2,487,825 Olvis Nov. 15, 1949