Method and apparatus for cleaning the inner and/or outer surfaces of a cuvette
United States Patent Gfeller Apr. 29, 1975 METHOD AND APPARATUS FOR CLEANING THE INNER AND/OR OUTER SURFACES OF A CUVETTE Primary ExaminerHouston S. Bell. Jr. Attorney, Agent, or Firm-Lawrence E. Laubscher [75] Inventor: Martin Gleller, Aurwangen Switzerland I [57] ABSTRACT [73] Assignee: Greiner Electronic AG, Langenthal Melhod and apparatus for cleaning inner and/0&#34; s it fl d outer surfaces of the receptacle of a fluid handling sysn I tern, for example. the transparent cuvette of a fluid- [..1 Filed. June 13.1973 specimen photometric inspection system, character- [211 App] 3 950 ized in that a cleaning fluid is drawn by suction successively across the outer surfaces of the cuvette from D the bottom wall toward the top wall, inwardly across [30] Forelg Apphcano Pnomy Data the top wall toward the fluid-receiving cavity conun 4. 19 2 z rland 8914/72 tained therein, and downwardly along the inner cavity wall surfaces of the cuvette, thereby to remove c0n- 15/302; l taminates from and to clean the surfaces of the cu- 3 1/ l4l/l30 vette. A cleaning head is provided with a chamber for [5 l] Int. Cl A47l 5/38 receiving in spaced relation the cuvette when arranged Fitild search-m /2l. in an inverted orientation. whereby rinsing or other l3 /l3l. 99; 23/253 R. 259 R; 5/30 30 fluid may be introduced into the space between the /89 0. 98 outer surfaces of the cuvette and the cleaning headv Suction means extend upwardly from the bottom wall [56] References Cited of the cleaning head chamber into the cuvette cavity UNITED STATES PATENTS and terminate in an orifice adjacent the bottom of the 3.2U2.l87 8/1965 Pcchmunn 1 141/92 Cam? 3.277329 ill/I966 Cook r r v l4l/92 3.495.291 2/1970 Cupping ct 111. 15/304 12 Clams 9 Draw F&#39;gum &#39;n n 24 22 i t, l  
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  I, 24 uuu w CLEANING HEAD B VERTICAL ms- PLACEMENT MEANS wAsl-u RINSE SUCTION 4o FLUID FLUID MEANS I 2 F g. .9 CLEANING SUCTION FLUID MEANS 2 m4 W} F. I02 Q N, l l 1&#34; n I H 5-: I ll CF: L l I000 I00 IOOb PI&#39;IEHTECAPRZSIBTS SHEET 2 Q5 9 I 84 62 i v RINSE V FLUID SUPPLY SUCTION MEANS 1 METHOD AND APPARATUS FOR CLEANING THE INNER AND/R OUTER SURFACES OF A CUVETTE This invention relates to an improved method and apparatus for cleaning and drying the outer and inner surfaces of the transparent cuvette of a photometric system for optically measuring and/or testing the characteristics of a fluid specimen.  
  It is well known in the fluid specimen testing art to mix chemical reagents with the specimen and then to optically inspect the resultant mixture with photometric means which include a light source that directs a light beam through the mixture. Normally the mixture to be tested is poured into a transparent cuvette for transport through the photometric inspection station. whereupon the mixture is dispensed from the cuvette and the cuvette is cleaned for subsequent reuse. One problem inherent in the prior systems is the difficulty in effectively cleaning both the inner and outer surfaces of the cuvettes, since many of the mixtures are relatively sticky and difficult to remove from the cuvette wall surfaces. The use of high temperature cleaning fluids--such as hot water--is not permitted when the euvettes are formed of a brittle material that is easily shattered, such as glass. Since undesirable residues from a prior specimen measurement will not only contaminate subsequent mixtures but also deleteriously impair the optical transmission of light through the cuvette and the specimen mixture, it is important that the residues be removed from the cuvettes as completely as possible.  
  Accordingly, the primary object of the present invention is to provide an improved method and apparatus for cleaning the outer and inner surfaces of the transparent cuvette of a fluid-specimen photometric testing system, characterized in that a cleaning fluid, such as rinse water. is drawn. in succession, longitudinally across the outer surface of the cuvette from the bottom wall to the top wall, inwardly along the top wall toward the specimen-receiving cavity contained therein, and downwardly along the inner wall surfaces of the cavity. In accordance with the invention, the cuvette is supported in an inverted condition. whereupon a cleaning head containing a chamber is displaced around the euvette with the chamber walls arranged adjacent and spaced from the outer surfaces of the cuvette. A suction member extends from the bottom wall of the cleaning head chamber upwardly in spaced relation within the cuvette cavity, said suction member containing a suction passage having an orifice immediately adjacent the bottom wall of the cuvette cavity.  
  According to a more specific object of the invention, a plurality of transparent cuvettes are arranged on an endless conveyor for transport between a specimen filling station, a specimen inspection station, a cuvette washing station and a cuvette rinsing and drying station. The endless conveyor includes vertically spaced horizontal upper and lower runs, said washing and said rinsing and drying stations being arranged beneath the lower horizontal runs for cleaning the cuvettes while in an inverted empty condition. Preferably the conveyor means is operable in a step-by-step manner, the cleaning head being movable toward and away from the cuvette at the rinsing and drying station during a dwell period of the conveyor. The dwell period of the conveyor is selected to permit sufficient time for the rinse fluid that is introduced between the outer surface of the euvette and the adjacent wall surfaces of the cleaning head chamber to be completely removed from the inner and outer surfaces by the flow of drying fluid produced by the suction means, whereby the cuvette will be in a fully dried condition when the cleaning head is removed therefrom at the end of the dwell period. Preferably a vacuum source of suitable suction pressure, such as a water jet pump, is operable to draw the drying fluid, such as air, through the space between the cleaning head and the cuvette to effect complete drying of the cuvette.  
  In accordance with a further object of the invention, means are provided for cleaning and/or drying either the inner surfaces of the fluid receptacle, the outer surfaces of the receptacle, or both the inner and outer surfaces of the receptacle. In the first instance, jets of washing, rinsing and/or drying fluids may be directed into the receptacle when in either the normal or an inverted position. To subject the outer surfaces of the re ceptacle to fluid treatment, a sectional head may be provided having head sections adapted for assembly about a receptacle when it is supported in a vertical orientation by means of pins that extend laterally from the upper end thereof. In the final case, the receptacle is supported in an inverted condition and the cleaning fluid flows successively along the outer, end and inner surfaces of the receptacle. Other objects and advantages of the invention will become apparent from a study of the following specification when viewed in the light of the accompanying drawing, in which:  
  FIG. 1 is a diagrammatic illustration of the specimen inspection and cuvette cleaning station;  
 FIG. 2 is an end elevation of the transparent cuvette;  
  FIG. 3 is a sectional view of the cuvette taken along line 3-3 of FIG. 2;  
  FIG. 4 is a perspective view, with certain parts broken away for clarity, of the rinsing head means;  
  FIGS. 5 and 6 are top plan and side elevation views, respectively, of the lower portion of the rinse head;  
  FIG. 7 is a sectional view taken along line 7-7 of FIG. 6&#39;.  
  FIG. 8 is a detailed sectional view illustrating the manner in which an inverted cuvette is rinsed and dried in the rinsing head; and  
  FIG. 9 is a diagrammatic illustration of the sectional head means for cleaning and/or drying the outer surfaces of the receptacle.  
  Referring more particularly to FIG. 1, the fluid specimen to be photometrically or optically analyzed is transported to the inspection station via mixing receptacles 2 each provided at its upper end with lateral pivot pins 2a. The receptacles are successively deposited on the pouring lever 4 which is pivoted about fixed pivot axis 6 by the cooperation between cam follower 8 and cam 10 which rotates about axis 12. A tilting slide rod I4 which reciprocates relative to fixed guides I6 by the cooperation between follower 18 and a second cam 20 serves to tilt the receptacle about its pivot pins 20 when the receptacle has been displaced by pouring lever 4 to a position above the upper run of endless conveyor 22. The cams l0 and 20 and the conveyor 22 are driven in timed relation by suitable drive means not shown.  
  Mounted in spaced relation on the endless conveyor 22 are a plurality of cuvettes 24 formed of a transparent material, such as glass. At the supply position I, a cuvette receives the liquid specimen that is poured from the tilted receptacle 2. Preferably the pouring arm 4 is arranged to position the pouring lip of the receptacle immediately adjacent the cuvette. whereby the introduction of deleterious air bubbles into the mixture to be tested is avoided. Following the pouring operation. the pouring arm 4 is pivotally retracted in the clockwise direction slightly beyond the illustrated position to effect gravity disposal of the empty mixing receptacle.  
  The cuvette is now conveyed by conveyor means 22 in a step-by-step manner toward the inspection station II, at which the fluid contents in the transparent cuvette are examined by the photometric means 22 which includes a light source which produces a light beam 28 that passes through the transparent cuvette and the fluid specimen, and photocell pick-up means (not shown) that measure the opacity or other characteristic of the specimen Preferably the liquid level of the specimen in the cuvette is just above the light beam 28, so that the minimum inner surface of the cuvette cavity is wetted by the specimen, thereby reducing to a minimum the surface area that requires cleaning. As the cuvette is transported further around the delivery end of the upper run, the photometrically tested fluid is poured by gravity into the return funnel 30.  
  During the return of the empty cuvettes along the lower run of conveyor means 22, each cuvette cavity is washed at washing station IV by cleansing fluid supplied under pressure from source 32 via nozzle means 34. The washed cuvette is then transferred to rinsing and drying station V, and during the dwell time that the cuvette is at this station, the cuvette cleaning head 36 is elevated by operating means (not shown) to partially enclose the downwardly directed cuvette as shown in FIG. 1. Rinsing fluid is initially supplied from rinsing fluid source 38, whereupon the chamber in the cleaning head is connected with the suction means 40 to withdraw all fluid from the chamber and thereby dry the inner (i.e., the cavity) and the outer wall surfaces of the cuvette. The cleaning head 36 is then retracted from the cuvette, whereupon the cleansed and thoroughly dried cuvette is transported to the supply end of the upper run for a further filling operation. Owing to the cleansing, rinsing and drying of the cuvette prior to return to the filling station I, all residue is completely removed from the cuvette surfaces that would otherwise deleteriously affect a subsequent photometric measurement.  
  As shown in FIGS. 2 and 3, each cuvette 24 is ofgenerally rectangular configuration and contains a cavity 24a having in longitudinal cross section the configuration defined by a line of generation transported parallel to itself along a generally parabolic path. As indicated above, the cuvette is formed of a transparent material, such as glass.  
  Referring now to FIGS. 4-7, the cuvette cleaning head 36 contains at its upper end an open-topped chamber 36a for receiving at rinsing and drying station V during corresponding dwell periods of conveyor means 22 successive downwardly directed cuvettes 24. Provided in spaced relation on the bottom wall 40 of chamber 36a are a plurality of spaced support feet 42 (FIGS. and 6) that support the inverted cuvette in spaced relation to the bottom wall 40 as shown in FIG. 8. Provided in spaced relation on the side walls 44, 46 and the end walls 48 and 50 of the chamber 36a are vertical spacer ribs 52 that engage the outer surfaces of the cuvette to maintain the cuvette spaced from the chamber wall surfaces. Similarly, a suction member 54 extends upwardly from the chamber bottom wall for insertion within the cuvette cavity, said suction member being provided with external vertical spacer ribs 56 that engage the cavity walls to support the cuvette in spaced relation to suction member 54 as shown in FIG. 6. Suction member 54 contains a vertical suction passage 58, the upper end of which terminates at an inlet orifice 58a adjacent but spaced from the bottom wall of the cuvette cavity 240. The lower end of scution passage 58 is connected with the cleaning head suction means 40 via conduit 60 and valve 62 as shown in FIG. 4. The rinse head includes movably connected auxiliary side wall sections 440 and 46a the upper ends of which extend above the corresponding side walls 44 and 46 respectively, said auxiliary side wall sections being biased inwardly toward each other by spring means (not shown). Spacer feet carried by the auxiliary sidewalls maintain the same in spaced relation relative to the external surfaces of the cuvette as shown in FIG. 8. The auxiliary side walls contain horizontal rinse passages 72 having discharge orifices 74 directed inwardly into chamber 360, said rinse passages being connected with the source of pressure rinse fluid 38 via conduits 76 and 78 and valve 80. Each auxiliary side wall further contains above the rinse passage a suction passage 82 that is connected with suction means 40 via conduits 84 and 86 and valve 88. The suction passages communicate with chamber 360 via vacuum slots 90. As shown in FIGS. 4 and 8, when valves 62 and are open and valve 88 is closed, rinse fluid is drawn by suction from orifices 74 downwardly in the space between the external wall surfaces of the cuvette and the side wall surfaces of chamber 36a. inwardly around the lower extremity of the cuvette, upwardly across the inner surfaces of the cuvette cavity 240, and downwardly through suction passage 58. When valves 62 and 88 are open and valve 80 is closed, the inner and outer surfaces of the cuvette are quickly dried by the vacuum removal of fluid therefrom. Consequently, in accor dance with the novel rinse head means of the present invention, a downwardly directed cuvette may be rinsed and dried within a single dwell period of the conveyor means 22 normally, about 6 seconds or less).  
  It is apparent that in accordance with one advantage of the invention, by reducing the uniform volume of the mixture fluid that is poured into the cuvette to the minimum amount required to just cover the light beam 28, the contaminated surface of the cuvette cavity requiring cleaning is reduced to a minimum, whereby the quantity of cleansing fluid required, the pouring time and the size and price of the cuvette are reduced to a minimum. Furthermore, the pouring time required for pouring the measured sample to waste is made as small as possible, thereby having more time for the other more substantial steps of one cycle of 6 second dwell.  
  Referring now to FIG. 9, sectional head means I00 are provided for subjecting only the outer surfaces of the receptacle with a fluid (for example, suction air in the case of a drying operation). The head means includes sections 1000 and 10% that are adapted to be brought together to enclose a receptacle 2 that is supported in the vertical orientation by means of the laterally extending pins at the upper end thereof. When the head sections are in the assembled condition illustrated by solid lines in FIG. 9, normally closed valve means 102 is opened to connect the space 104 between the outer surfaces of the receptacle and the inner wall surfaces of the cleaning head with the suction source 40, whereby the outer surface of the receptacle is dried. In the alternative, normally closed valve means 106 may be opened to permit cleaning fluid (such as a wash or a rinse fluid) under pressure to be supplied to the space 104 from the cleaning fluid source 108. ln this manner, cleaning of the outer surfaces only of the receptacle may be effected.  
  While in accordance with the provisions of the Patent Statutes the preferred form and embodiment of the present invention has been illustrated and described, it will be apparent that other modifications may be made without deviating from the inventive concept.  
 What we claim is:  
  1. Apparatus for cleaning the transparent cuvette of a fluid specimen photometric testing system, comprisa. means for supporting the cuvette in an inverted condition;  
 b. a cleaning head member containing at its upper end an upwardly directed open-topped chamber for receiving said inverted cuvette, said head mem ber including bottom, side and end walls defining said chamber;  
 c. suction means extending from the bottom wall of said chamber upwardly within the cavity contained in said cuvette, said suction means containing a vertical suction passage having a first orifice at its upper end adjacent and spaced from the bottom portion of the cuvette cavity;  
 d. means for initially supplying a fluid in said chamber adjacent the upper portion of the space between said cuvette and said side walls; and  
 c. means subsequently connecting the lower end of said suction passage with a vacuum source, whereby said fluid is drawn by suction downwardly along the cuvette outer wall surfaces, inwardly along the end surface of the cuvette, upwardly along the inner wall surfaces of the cuvette cavity, and downwardly through said suction passage, thereby to clean the outer and inner surfaces of the cuvette.  
  2. Apparatus as defined in claim 1, and further including auxiliary suction passages contained in said chamber side walls and having second orifices arranged above said fluid supply means for communication with the upper portion of the space between said chamber walls and said cuvette, and means connecting said auxiliary suction passages with said vacuum source.  
  3. Apparatus as defined in claim I, wherein said fluid comprises a quantity of rinsing liquid, and further wherein said suction passage is connected with said vacuum source for a sufficient period of time to effect complete removal of said rinsing liquid from, and thereby completely dry, the inner and outer surfaces of said cuvette.  
  4. Apparatus as defined in claim 3, and further including washing means arranged remote from said cleaning head member for initially introducing cleansing fluid into the cuvette cavity; and conveyor means for transporting said cuvette from said washing means to said cleaning head member.  
  5. Apparatus as defined in claim 4, wherein said conveyor means comprises an endless conveyor having vertically spaced upper and lower horizonital runs, said cuvette being carried by said conveyor means with the cuvette cavity directed outwardly therefrom, said washing means and said cleaning head being arranged adjacent the lower run of said conveyor means.  
  6. Apparatus as defined in claim 5, wherein said endless conveyor means is operable in a step-by-step manner, and further wherein said cleaning head is adapted for vertical reciprocatory movement relative to said conveyor to insert said suction means within and to withdraw said suction means from said cavity, respectively, during dwell periods of the conveyor travel.  
  7. Apparatus as defined in claim 1, and further including a plurality of laterally spaced first vertical spacer ribs arranged on the lower portions of the side and end walls of the cleaning head chamber for engagement with the corresponding external wall surfaces of said cuvette, thereby to support said cuvette in spaced relation from said chamber side and end walls.  
  8. Apparatus as defined in claim 7, and further including a plurality of laterally spaced second vertical spacer ribs arranged on the walls of said suction means for engagement with the wall surfaces of the cuvette cavity, said suction member containing a vertical suction passage having an inlet at its upper end adjacent the cavity bottom wall of the downwardly directed cuvette, said suction passage being connected at its lower end with a source of suction pressure.  
  9. Apparatus as defined in claim 8, wherein each of said side walls contains adjacent its upper end rinse orifice means for supplying said rinsing fluid in the space between said external surfaces of said cuvette and the corresponding side wall surfaces of said chamber, whereby when said suction passage is connected with said suction source, said rinsing fluid is drawn downwardly along the external surfaces of said cuvette, upwardly along the cavity inner wall surface, and downwardly through said suction passage.  
  10. Apparatus as defined in claim 9, wherein said rinsing head side walls include adjacent their upper ends above said rinse orifice means:  
 a. a plurality of spaced upper side wall stop feet for engaging the adjacent external surfaces of the downwardly directed cuvette; and  
 b. auxiliary suction orifices for withdrawing by suction fluid contained in the upper portion of said chamber.  
  11. Apparatus as defined in claim 10, wherein the upper portions of said rinsing head side walls are sectional and are connected for movement toward and away from each other, and further including spring means biasing said side walls toward each other into engagement with said cuvette.  
  12. Apparatus as defined in claim 5, and further including means for displacing said cleaning head toward said lower run in timed relation to the transport of said empty cuvettes, thereby to effect reception of a given cuvette by the chamber of the cleaning head.