Abstract:
A dual-chambered dispensing device having a single piston. The device is driven by an electric precision motor. Each chamber is capable of aspiration and dispensation. When one chamber is aspirating, the other is dispensing.

Description:
FIELD OF THE INVENTION 
   This invention relates to fluid displacement devices. More particularly, this invention relates to single piston, dual chambered fluid displacement devices. 
   BACKGROUND OF THE INVENTION 
   Pipetting fluid for chemical analysis has been known for some time. Automated pipetting of fluids is a more recent trend. Automated pipetting includes precision metering of fluids. To aspirate one fluid while simultaneously dispensing another with one single device has been an elusive problem in this field. 
   The following prior art reflects the state of the art of which applicant is aware and is included herewith to discharge applicant&#39;s acknowledged duty to disclose relevant prior art. It is stipulated, however, that none of these references teach singly nor render obvious when considered in any conceivable combination the nexus of the instant invention as disclosed in greater detail hereinafter and as particularly claimed. 
   
     
       
             
           
             
             
             
             
           
             
           
             
             
             
             
           
         
             
                 
             
           
           
             
               U.S. PATENT DOCUMENTS 
             
           
        
         
             
                 
               U.S. PAT. NO. 
               ISSUE DATE 
               INVENTOR 
             
             
                 
                 
             
             
                 
               1,135,476 
               Apr. 13, 1915 
               Watts 
             
             
                 
               1,170,958 
               Feb. 8, 1916 
               Butler 
             
             
                 
               1,499,662 
               Jul. 1, 1924 
               Jubé 
             
             
                 
               1,850,132 
               Mar. 22, 1932 
               Morse 
             
             
                 
               2,028,161 
               Jan. 21, 1936 
               Mann 
             
             
                 
               2,062,285 
               Dec. 1, 1936 
               Bergman 
             
             
                 
               2,093,344 
               Sep. 14, 1937 
               Wandel 
             
             
                 
               2,410,808 
               Nov. 12, 1946 
               Christensen 
             
             
                 
               3,426,657 
               Feb. 11, 1969 
               Bimba 
             
             
                 
               3,464,359 
               Sep. 2, 1969 
               King, et al. 
             
             
                 
               4,065,230 
               Dec. 27, 1977 
               Gezari 
             
             
                 
               4,089,624 
               May 16, 1978 
               Nichols, et al. 
             
             
                 
               4,242,058 
               Dec. 30, 1980 
               Zakora 
             
             
                 
               4,457,747 
               Jul. 3, 1984 
               Tu 
             
             
                 
               4,481,946 
               Nov. 13, 1984 
               Altshuler, et al. 
             
             
                 
               4,486,188 
               Dec. 4, 1984 
               Altshuler, et al. 
             
             
                 
               4,695,431 
               Sep. 22, 1987 
               Farrell 
             
             
                 
               4,898,579 
               Feb. 6, 1990 
               Groshong, et al. 
             
             
                 
               4,941,808 
               Jul. 17, 1990 
               Qureshi, et al. 
             
             
                 
               5,328,459 
               Jul. 12, 1994 
               Laghi 
             
             
                 
               5,366,904 
               Nov. 22, 1994 
               Qureshi, et al. 
             
             
                 
               5,407,424 
               Apr. 18, 1995 
               LaFontaine, et al. 
             
             
                 
               5,492,535 
               Feb. 20, 1996 
               Reed, et al. 
             
             
                 
               5,529,463 
               Jun. 25, 1996 
               Layer, et al. 
             
             
                 
               5,540,562 
               Jul. 30, 1996 
               Giter 
             
             
                 
                 
             
           
        
         
             
               FOREIGN PATENT DOCUMENTS 
             
           
        
         
             
               PATENT NO. 
               COUNTRY 
               PUBLICATION DATE 
               APPLICANT 
             
             
                 
             
             
               706,280 
               FR 
               Jun. 20, 1931 
               Denoncourt 
             
             
                 
             
           
        
       
     
   
   The prior art listed above, but not specifically discussed, teach other devices for pumping or displacing fluids and further catalog the prior art of which the applicant is aware. These references diverge even more starkly from the references specifically distinguished above. 
   SUMMARY OF THE INVENTION 
   A device having two chambers for containing fluids and two ports, one port per chamber, is disclosed. This device contains a single piston that may travel through both chambers and a means is provided for sequestering the fluids in the individual chambers. Hence, when the piston is driven through the chambers, one port will aspirate fluid while the other will dispense fluid. These roles will reverse upon the piston traveling in the opposite direction. Significantly, where the chambers are of equal size, any amount aspirated in one chamber will be equal to the amount dispensed from the other. 
   By coupling the piston to a precise motor driving means, very precise aspiration and dispensation may be achieved. Furthermore, by providing stops on a shaft coupled to the piston, overshooting of the piston can be avoided. By combining these roles in a single device, certain efficiencies are achieved that are desirable in commercial laboratories. 
   OBJECTS OF THE INVENTION 
   It is a first object of this invention to provide a device that may simultaneously dispense and aspirate fluids. 
   It is another object of the present invention to provide a device that will provide such dispensation and aspiration in a precisely metered fashion. 
   It is another object of the present invention to provide a device that will work in an automated environment. 
   It is another object of the present invention to minimize the number of parts contained in such invention. 
   It is another object of the present invention to provide such a device in a plastic molded format to, inter alia, provide cost reduction means. 
   It is another object of the present invention to provide limit stops on the invention to prevent the invention from overshooting. 
   It is another object of the present invention to provide equal displacement between the chambers of the invention. That is, that the amount aspirated from one chamber is the same amount being dispensed from the other chamber. 
   It is yet another object of the present invention to provide a device that is minimal in size so as to facilitate coordination with other such related equipment and enhance ease of movement within a laboratory environment. 
   Viewed from a first vantage point, it is an object of the present invention to provide a dispenser for preparing samples, comprising, in combination, a syringe having a hollow with a first chamber and a second chamber, the chambers sequestered one from the other by piston means, and means to directly drive the piston means axially through the chambers. 
   Viewed from a second vantage point, it is an object of the present invention to provide a method for preparing samples, the steps including, connecting a syringe to first and second fluid sources, sequestering the first and second fluids in the syringe into a first and second area, respectively, driving a piston in the syringe to alternatively dispense and receive the fluids in the sequestered areas by a drive motor, and controlling the drive motor. 
   Viewed from a third vantage point, it is an object of the present invention to provide a dispenser for transferring fluids, comprising, in combination, two shafts, a piston between each shaft, a cylinder provided about the shafts defining two chambers sequestered one from the other by the piston, two seals coupled to the cylinder and about the shafts, one per shaft, wherein the seals are impervious to fluids, and wherein the piston, the seals, the cylinder, and the shafts define two chambers sequestered from each other, and two ports, one per chamber, in fluid communication with the chambers. 
   These and other objects will be made manifest when considering the following detailed specification when taken in conjunction with the appended drawing figures. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  depicts one embodiment of the syringe. 
       FIGS. 2A and 2B  are exploded parts views of two distinct embodiments of the syringe. 
       FIG. 3  depicts another embodiment of the syringe. 
       FIG. 4  is a cross-sectional view of the syringe of FIG.  3 . 
       FIG. 5  depicts a preferred embodiment of the syringe. 
       FIG. 6  is a cross-sectional view of the syringe of  FIG. 5  taken along line  6 — 6 . 
       FIG. 7  depicts the syringe being inserted into the motorized coupling. 
       FIG. 8  depicts the syringe mounted to the syringe drive unit. 
       FIG. 9  is a cutaway perspective view of the syringe drive unit depicting the insides thereof including motor and gears. 
       FIG. 10  is a front view of the circuit components with the syringe drive unit. 
       FIG. 11  is a schematic depiction of the circuit of the syringe drive unit. 
       FIGS. 12A and 12B  are cross-sectional views of the syringe embodiments that include a spacer. 
       FIG. 13  is a cross-sectional view of an alternative plunger tip. 
   

   DESCRIPTION OF PREFERRED EMBODIMENTS 
   Considering the drawings, wherein like reference numerals denote like parts throughout the various drawing figures, reference numeral  10  is directed to the precision aspiration and dispensation apparatus according to the present invention. 
   The main components of the invention at hand are as follows: two chambers  64 ,  66 ; two ports  58 ,  60 , one port per chamber; and a rod  72 , having a piston for sequestering the contents of each said chamber. 
   Now referring to  FIGS. 1 and 2A , an initial embodiment of the invention will be herein described. Syringe  110  consists of an upper housing  12  and a lower housing  14  having a barrel  38  therebetween and a piston rod  72  therethrough. Preferably, the barrel  38  is of a cylindrical shape. Each housing  12 ,  14  further has located thereon ports  58 ,  60 , one per housing. A cap  16  is coupled to the upper housing  12  to ensconce one end  24  of the piston rod  72 . At the other end of the piston rod  72  is coupled a button  34  by means of a set screw  52 . A mounting post  18  is further provided on upper housing  12  and coupled by weld area  20  to mate with a mounting bore  82  on a syringe drive unit for motor housing  74  (as depicted in FIGS.  7  and  8 ). 
   The piston rod  72  itself may be comprised of several components. On smaller syringes, an upper shaft  24  and a lower shaft  22  are coupled to a shaft insert  26 . On larger syringes, the rod  72  is one piece. Shaft insert  26  also has thereon an O-ring  56  for slideably receiving a plunger tip  32  thereon. The combination of the plunger tip  32 , shaft insert  26  and O-ring  56 , as depicted, together comprise what may better be described as a piston to inhibit fluids in one chamber from gaining access to another chamber. 
   A stop is also provided in the form of E-ring  54  on a terminal end of the upper shaft  24 . The upper shaft  24  passes through the housing  12 , which contains an upper seal  30 , upper O-ring  50 , upper bearing  42 , and cap  16 . Such stop prohibits upper shaft  24  from axially sliding too far within upper housing  12 . Similarly, lower shaft  22  passes through, at its terminal end, a lower seal  28 , O-ring  47 , lower bearing  40 , and end  36  contained in housing  14 . The shaft has at its end the previously described button  34 . 
   Each port  58 , 60  is able to accomplish the double duty of aspiration and dispensation. 
     FIG. 2B  depicts a second embodiment of the invention. In this embodiment, lower seal  28  is replaced by back-up ring  128  and lower bearing  40  is replaced by a seal/bearing combination  140 . O-ring  47  sits between back-up ring  128  and seal/bearing  140 . 
   Referring now to  FIGS. 3 and 4 , another embodiment is depicted with the following variations. Button  34  has taken on a new shape to better fit and form for manipulation by syringe drive unit  74 . Barrel  38  is transparent or semi-transparent with hash marks optionally thereon to allow visible assurity. 
   As can be particularly seen in  FIG. 4 , fluids passing though ports  58 ,  60  will then pass through channels  90 ,  92 , respectively, and thereafter into upper chamber  64  and lower chamber  66 . The upper chamber  64  and lower chamber  66  are defined by that space not occupied by piston rod  72 , or more particularly, upper shaft  24 , lower shaft  22 , plunger tip  32 , and tip stop  62 . Clearly, by varying the size of the barrel  38  or the size of the upper shaft  24  or lower shaft  22 , the volumes of chambers  64 ,  66  may be varied. 
   As further depicted in  FIGS. 5 and 6 , a preferred embodiment is shown made of an economically mass produceable material, such as plastic, wherein certain parts have been combined or eliminated for efficiency purposes and to reduce costs. In particular, and as can be seen in  FIG. 6 , shaft insert  26  is a variation for this embodiment for easier insertion and manipulation. Vent  70  has been added to allow venting of air as piston rod  72  travels within cap  16 . As can also be seen, many items have been molded together to form single components instead of multiple components. 
     FIGS. 7 through 10  include syringe drive unit  74 . In particular,  FIG. 7  shows syringe  110  being mated with syringe drive unit  74  within syringe relief  80 . As shown, mounting bore  82  will receive mount  18  and piston agitation surface  76  will receive button  34 , coupleable by button coupling means  78  into button  34 . Release lever  88  is also provided to so release mount  18  from bore  82  as needed by expanding biased ring  106  when release lever  88  is depressed. Biased ring  106  is normally biased inward within bore  82  to hold fast a mount  18 . By pressing release lever  88  toward syringe drive unit  74 , release arm  104  arcs toward arrow R and likewise causes biased ring release  120  to pull biased ring  106  outward. Due to spring  102  connected to release arm  104 , when one frees the release lever  88 , the bias of spring  102  causes release lever  88  to again project outward and bias ring  106  to constrict within mounting bore  82 . 
   As shown in  FIG. 8 , syringe  110  is coupled to housing  74  to so comprise the invention  10 . 
     FIG. 9  shows in cutaway the drive mechanism for the precision piston agitation surface. Included therein are a motor  94 , preferably a DC servomotor, and an elongated worm gear  96 , wherein a belt  112  couples the motor to the gear. A carriage  98  is carried upon gear  96  and also upon a guide  118 . As the worm gear  96  turns, the carriage  98  may move upwardly or downwardly. Coupled to the carriage is the piston agitation surface  76  which would likewise move upwardly or downwardly with the carriage. Also included upon the worm gear are a lower spring restraint  114  and an upper spring restraint  116 . The springs may act against the action of the motor gearing to preclude drift of the carriage upwardly or downwardly. To control the motor  94  is a circuit board  108  containing a PID programmable microprocessor thereon. Wires  100  extending from motor  94  are coupled to and circuitously engaged with circuit board  108 . Circuit board  108  additionally has an interface  122  which may couple to a user interface such as a keyboard or computer. Interface  122  may be of any variety of interfaces capable of carrying signals such as a serial or parallel interface. The flow diagram of  FIG. 11  further depicts schematically the circuit described hereinabove. 
   In use and operation (FIG.  8 ), when a piston rod  72  is fully inserted within chambers  64 ,  66 , withdrawing piston rod  72  axially from those chambers along arrow A will result in fluid being dispensed from chamber  66  through port  60  and fluid being aspirated into chamber  64  through port  58 . Thereafter, pushing that same piston rod  72  in the opposite direction along arrow B will cause the opposite result, that is, aspiration via port  60  and dispensation via port  58 . Of course, the length of the stroke of piston rod  72  will be proportional to the amounts aspirated and dispensed from the chambers. Therefore, by utilizing motor  94  precisely, very specific amounts of fluid can be dispensed and aspirated simultaneously. This can readily be accomplished by a number of motors, especially an appropriately configured DC servomotor, as will now be evident to those having ordinary skill in the art, informed by the present disclosure. 
   Additionally, by coupling the syringe drive unit  74  to a computer control means, such as a microprocessor within said drive unit, even more precise metering can be accomplished in plunging and extracting the piston  72 . 
     FIGS. 12A and 12B  show another embodiment of the invention, in which an annular spacer  150  has been inserted in the end of the syringe having the button  34  (rather than that having the cap  16 ). The spacer is located inboard of and adjacent to O-ring  47 . The spacer  150  creates a pocket  152  in which fluid pools, which keeps the area lubricated and increases the longevity of the instrument. The plunger tip  32  and O-ring  56  assembly is replaced by a combination of wipers  31  and O-rings  33 . 
     FIG. 13  depicts another combination that replaces the plunger tip  32  and O-ring  56  assembly, which utilizes two O-rings  133 . The O-rings  133  are located on the shaft insert  126  and are separated from the barrel  38  by a pair of wipers  131 . The combination of these elements (in all embodiments of FIGS.  12 A, 12 B, 13 ) produces static seals S and dynamic seals D (as the shaft moves along arrow M) to prevent fluid leakage and additionally prolong the life of the instrument. 
   Moreover, having thus described the invention, it should be apparent that numerous structural modifications and adaptations may be resorted to without departing from the scope and fair meaning of the instant invention as set forth hereinabove and as described hereinbelow by the claims.