Patent Publication Number: US-7214039-B2

Title: Integrated ratio pump and check valve apparatus

Description:
BACKGROUND OF THE INVENTION 
   This invention relates to an integrated ratio pump and check valve apparatus for pumping a plurality of discrete liquid volumes to points of use of the liquid volumes. More particularly, this invention relates to an integrated ratio displacement pump and check valve apparatus for pumping a plurality of discrete liquid volumes to points of use. 
   At the present time, discrete liquid volumes are pumped with a syringe pump comprising a barrel, a face seal which moves within the barrel and a reciprocating plunger attached to the face seal. The syringe pump includes a valve construction formed of a polymeric composition which directs the pumped liquid volumes to a point of use. The valve construction includes a housing (stator) having a hollow, essentially interior surface into which is press fit a mating rotor. The rotor is provided with fluid passageways that control flow of liquid into the syringe pump and flow of liquid from the syringe pump while providing sealing between a pump inlet and a pump outlet. This configuration of syringe pump and rotor-stator valve requires two motors, one to drive the syringe and a second to drive the rotor. 
   While the available syringe pumps have been useful for their intended purpose, they also have disadvantages. In order to attain a tight fit between the barrel and the face seal, the manufacturing of both the barrel and face seal must be made at tight tolerances. In addition, when utilizing the most commonly used materials comprising a glass barrel and a polytetrafluoroethylene (PTFE) face seal, undesirable shedding of the PTFE occurs which contaminates the liquid being pumped. Furthermore, a tight fit between the barrel and face seal results in chattering of the face seal during its movement within the barrel. This leads to a loss of control of the liquid volume being pumped. In addition, the average useful life of presently available syringe pumps is only about 10 to about 100,000 cycles. 
   The presently available syringe pumps also are capable of pumping only a single liquid. Oftentimes it is desirable to provide a mixture of two or more liquid compositions for specific purposes. The provision of such liquid mixtures is not possible with presently available syringe pumps. 
   Accordingly, it would be desirable to provide a pump apparatus capable of delivering discrete liquid volumes to a point of use such as different areas of a sample tray in a manner which is repeatable for long time periods of 1,000,000 cycles or more. In addition, it would be desirable to provide such a pump apparatus which avoids shedding of particles during pumping. Furthermore, it would be desirable to provide such a pump which eliminates the need for a motor to activate a seal in order to direct fluid to a desired point of use. In addition, it would be desirable to provide such a pump apparatus capable of pumping a plurality of liquids in precise volume ratios. 
   SUMMARY OF THE INVENTION 
   The present invention provides a pumping apparatus comprising a plurality of sets of (a) a displacement pump having a liquid displacement element comprises a piston housed within a barrel, a high pressure seal and means for reciprocating the piston within the barrel and (b) check valves wherein the sealing is effected by activating a movable element under pressure of fluid being pumped without use of a motor. The pistons of each displacement pump are reciprocated by a common motor. Liquid in the barrel of each displacement pump is delivered to a point of use while the piston is traveling toward a check valve positioned between the piston and the point of use and liquid is supplied to each barrel when the piston is traveling away from the check valve positioned between the piston and the point of use. Each moving piston is spaced apart from the inside surface of each barrel so that a frictional force between the piston and the barrel is prevented during pumping. By providing check valves (a) between the piston and the point of use and (b) between the piston and a source reservoir for the liquid, motors for positioning the valves can be eliminated. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1A  is a cross-sectional view of the displacement pump and check valve apparatus of  FIG. 1B  taken along line  1 A— 1 A. 
       FIG. 1B  is a front view of the displacement pump and check valve apparatus of  FIGS. 1A and 1C . 
       FIG. 1C  is a cross-sectional view of the displacement pump and check valve apparatus of  FIG. 1B  taken along line  1 C— 1 C. 
       FIG. 2A  is a cross-sectional view of the displacement pump and check valve apparatus of  FIG. 2B  taken along line  2 A— 2 A. 
       FIG. 2B  is a front view of the displacement pump and check valve apparatus of  FIG. 2A and 2C . 
       FIG. 2C  is a cross-sectional view of the displacement pump and check valve apparatus of  FIG. 2B  taken along line  2 C— 2 C. 
       FIG. 3A  is a cross-sectional view of the displacement pump and check valve apparatus of  FIG. 3B  taken along line  3 A— 3 A. 
       FIG. 3B  is a front view of the displacement pump and check valve 
     apparatus of  FIG. 3A and 3C . 
       FIG. 3C  is a cross-sectional view of the displacement pump and check valve apparatus of  FIG. 3B  taken along line  3 C— 3 C. 
       FIG. 4  is a side view of a displacement pump and check valve apparatus of this invention.  FIG. 5  is a cross-sectional view of the check valve useful in the present invention. 
   

   DESCRIPTION OF SPECIFIC EMBODIMENTS 
   Referring to  FIG. 4 , the pump apparatus  10  of this invention includes a housing  12  and a motor  16  which effects rotation. Housing  32  which can be formed of an opaque or transparent material which is resistant to the liquid being pumped such as acrylic, polyetherether ketone, or the like can be a single piece or a plurality of joined elements. Each piston  34  of each pump can be formed of sapphire, glass or a ceramic or the like and is spaced apart from the interior wall  38  of housing  32  to form a barrel  29 . When each piston  34  is so-positioned, a single stroke of each piston  34  during use of the pump will deliver a known volume of liquid depending upon the piston diameter, the barrel diameter and the stroke length. The provision of a single element housing provides the advantage that the valve seats and displacement pump of this invention can be replaced simultaneously after the useful life of the pump is completed. 
   Motor  16  causes gear box  40  to reciprocate through pulley  41 , and gears  42 ,  44  and  46  and gear track  48 . Gear box  40  is positioned within track  47  which causes the piston  34  of each pump to move in a repeatable linear path stroke after stroke. As shown in  FIG. 4 , the stroke of the pump varies from position  50  and position  52  which typically can be between about 1.5 and 2.0 inches. It is to be understood that any conventional activating apparatus which causes each piston  34  to reciprocate on a linear path can be utilized in the present invention. 
     FIGS. 1A ,  1 B and  1 C show the embodiment of this invention wherein two liquids are simultaneously pumped without the use of a wash liquid for the pump seals. Each piston  34 A and  34 B is positioned within a seal  56 A or  56 B which can be formed, for example of ultra high molecular weight polyethylene (UHMWPE) or the like and optional roulon guide  58 A or  58 B. The roulon guides  58 A and  58 B align pistons  34 A and  34 B into seals  56 A and  56 B. The pistons  34 A and  34 B reciprocate within seals  56 A and  56 B and roulon guides  54 A and  54 B. The pistons  34 A and  34 B are fixedly positioned in ferrules  60 A and  60 B which, in turn, are fixed within arm  62  by knobs  64 A and  64 B. Both pistons move when arm  62  is moved. The volume ratio of the liquids delivered from barrels  29 A and  29 B with a single stroke of pistons  34 A and  34 B is controlled by the ratio of the sizes of the pistons  34 A and  34 B. 
   As shown in  FIGS. 1A ,  1 B and  1 C, the housing  32  can be formed of three pieces,  32 A,  32 B and  32 C. Housing piece  32 C includes four valve seats  31 ,  33 ,  35  and  37  into which are positioned check valves  39 ,  41 ,  43  and  45 . Check valves  39 ,  41 ,  43  and  45  can have threads  47 ,  49 ,  51  and  53  to screw the valves  39 ,  41 ,  43  and  45  into valve seats  31 ,  33 ,  35  and  37  having internal threads (not shown). Housing  32   c  can be provided with threads  55  and  57  to secure housings  32 A and  32 B to housing  32 C. Check valves  41  and  45  are connected to conduit  59  and  61  which in turn are in fluid communication with a point of use for the fluid (not shown). Check valves  39  and  43  are connected with conduits  63  and  65  which, in turn, are connected to a reservoir for the fluid (not shown). In use, when pistons  34 A and  34 B move toward check valves  41  and  45 , check valves  41  and  45  are open and check valves  39  and  43  are closed so that fluid is delivered through check valves  41  and  45  and conduits  59  and  61  to a point of use of the fluids. When pistons  34   a  and  34   b  move away from check valves  41  and  45 , check valves  41  and  45  are closed and check valves  39  and  43  are open so that fluid moves into barrel  29 A and  29 B through check valves  39  and  43  and conduits  63  and  65  from a fluid reservoir. 
     FIGS. 2A ,  2 B and  2 C show the embodiment of this invention wherein two liquids including a wash liquid for the pump seals are simultaneously pumped. Each piston  34 C and  34 D is positioned within a seal  56 C or  56 D which can be formed, from (UHMWPE) or the like and optional roulon guide  58   c  or  58 D. The roulon guides  58 C and  58 D align pistons  34 C and  34 D into seals  56 C and  56 D. The pistons  34 C and  34 D reciprocate within seals  56 C and  56 D and roulon guides  54 C and  54 D. The pistons  34 C and  34 D are fixedly positioned in ferrules  60 C and  60 D which, in turn, are fixed within arm  62 A by knobs  64 C and  64 D. Both pistons  34 E and  34 F move together when arm  62 A is moved by motor  16  ( FIG. 4 ). The volume ratio of the liquids delivered from barrels  29 C and  29 D with a single stroke of pistons  34 E and  34 F is controlled by the ratio of the sizes of the pistons  34 E and  34 F. 
   As shown in  FIGS. 2A ,  2 B and  2 C, the housing  32 D can be formed of three pieces comprising piece  32 E,  32 F and  32 G. Housing piece  32 G includes four valve seats  67 ,  69 ,  71  and  73  into which are positioned check valves  75 ,  77 ,  79  and  81 . Check valves  75 ,  77 ,  79  and  81  can have threads  83 ,  85 ,  87  and  89  to screw the valves  75 ,  77 ,  79  and  81  into valve seats  67 ,  69 ,  71  and  73  having internal threads (not shown). Housing  32   g  can be provided with threads  91  and  93  to secure housings  32 E and  32 F to housing  32 G. Check valves  79  is connected to conduit  95  which in turn is connected to a reservoir for wash water (not shown). Check valve  81  is connected to conduit  97  which, in turn, is connected to seal  56 C in order to deliver wash water to seal  56 C. Conduit  99  is connected to seal  56 C to remove wash water from seal  56 C. The wash water substantially prevents build-up of contaminants within seal  56 C. Check valve  75  is connected to conduit  96  which, in turn, is in fluid communication with a reservoir for a fluid (not shown). Check valve  77  is connected to conduit  98  which directs pumped fluid to a point of use (not shown). In use, when pistons  34 A and  34 B move toward check valves  77  and  79 , check valves  81  and  83  are open and check valves  75  and  79  are closed so that fluid is delivered through check valve  77  and conduits  98  to a point of use of a fluid. In addition, wash water is delivered through check valve  81  and conduit  97 . When pistons  34 E and  34 F move away from check valves  77  and  81 , check valves  77  and  81  are closed and check valves  75  and  79  are open so that fluid moves into barrels  29 C and  29 D through check valves  75  and  79  and conduits  95  and  96  from a fluid reservoir (not shown). 
     FIGS. 3A ,  3 B and  3 C show the embodiment of this invention wherein three liquids including a wash liquid for the pump seals are simultaneously pumped. Each piston  34 G,  34 H and  34 I is positioned within a seal  56 E,  56 F or  56 G which can be formed, from UHMWPE or the like and optional roulon guides  58 E,  58 F or  58 G. The roulon guides  58 E,  58 F and  58 G align pistons  34 G,  34 H and  34 I into seals  56 E,  56 F and  56 G. The pistons  34 G,  34 H and  34 I reciprocate within seals  56 E,  56 F and  56 G and roulon guides  54 E,  54 F and  54 G. The pistons  34 G,  34 H and  34 I are fixedly positioned in ferrules  60 E,  60 F and  60 G which, in turn, are fixed within arm  62  by knobs  64 E,  64 F and  64 G. All three pistons  34 G,  34 H and  34 I move when arm  62 A is moved. The volume ratio of the liquids delivered from barrels  29 C,  29 D and  29 E with a single stroke of pistons  34 G,  34 H and  34 I is controlled by the ratio of the sizes of the pistons  34 G,  34 H and  34 I. 
   As shown in  FIGS. 3A ,  3 B and  3 C, the housing  32 H can be formed of four pieces comprising pieces  32 I,  32 J,  32 K and  32 L. Housing piece  32 I includes six valve seats  66 ,  68 ,  70 ,  72 ,  74  and  76  into which are positioned check valves  78 ,  80 ,  82 ,  84 ,  86  and  88 . Check valves  78 ,  80 ,  82 ,  84 ,  86  and  88  can have threads e.g.,  90 ,  92 ,  94  and  100  to screw the valves  78 ,  80 ,  82 ,  84 ,  86  and  88  into valve seats  66 ,  68 ,  70 ,  72 ,  74  and  76  having internal threads (not shown). Housing  32 H can be provided with threads  102 ,  104  and  106  to secure housings  32 I,  32 J and  32 K to housing  32 H. Check valve  88  is connected to conduit  108  which in turn is connected to a reservoir for wash water (not shown). Check valve  86  is connected to conduit  110  which, in turn, is connected to seals  56 E and  56 F in order to deliver wash water to seals  56 E and  56 F. A conduit  112  connects seal  56 F to seal  56 E so that both seals  56 E and  56 F receive wash water. Conduit  114  is connected to seal  56 E to remove wash water from seals  56 E and  56 F. Check valve  80  is connected to conduit  116  which, in turn, is in fluid communication with a reservoir for a fluid (not shown). Check valve  78  is connected to conduit  118  which directs pumped fluid to a point of use (not shown). In use, when pistons  34 G,  34 H and  34 I move toward check valves  78 ,  82  and  86 , check valves  78 ,  82  and  86  are open and check valves  80 ,  84  and  88  are closed so that fluid is delivered through check valves  78  and  82  and conduits  118  and  119  to a point of use of a fluid. In addition, wash water is delivered through check valve  86  and conduit  110 . When pistons  34 G,  34 H and  34 I move away from check valves  78 ,  82  and  86 , check valves  78 ,  82  and  86  are closed and check valves  80 ,  84  and  88  are open so that fluid moves into barrels  29 E,  29 F and  29 G through check valves  80 ,  84 , and  88  from a fluid reservoir (not shown). 
   Referring to  FIG. 5 , the valve  41 , like valves  39 ,  43  and  45  includes a movable ball  101  which moves within valve seat  103  to block either conduit  105  or conduit  107  to effect fluid flow as described above.