Liquid Transfer Valve Structure

1. Field of the Invention

This invention relates generally to liquid transfer systems and more particularly provides a pneumatically operated liquid transfer valve having a linearly movable valve element carrying measuring passageways oriented to effect gravity induced drainage.

2. Description of the Prior Art

In the U.S. Pat. No. 3,549,994, there was provided a structure in which a sample of blood is driven into a fluid system in which it is accurately diluted with a suitable diluent and divided into two samples for red and white blood cell determination. The red sample for red cell determination is counted and sized utilizing a COULTER scanning device and is discharged, while at the same time the other is lysed to break up the red cells and subjected to another COULTER electronic scanning device for a white cell count with the simultaneous examination of the sample for hemoglobin determination and discharge. Processing is automatic and continuous for samples drawn into the apparatus at intervals exceeding at least a certain minimum time duration. The structure therein disclosed included means for combining the data automatically to ascertain certain of the parameters which are susceptible of derivation for determinations made, and producing data corresponding to all of the parameters both determined and derived from the apparatus. These parameters were blood counts, sizes, percentages, and the like, accepted in the medical arts as aids for diagnosis, treatment, and research. The structure therein disclosed utilized vessels, valves, and connecting conduits for the intermixing and/or diluting of fluids primarily for the purpose of making measurements and tests on such fluids. Of course, it should be appreciated that such description is somewhat general and while primarily utilized with an automatic instrument such as disclosed in the above-identified patent and employs the particle analyzing apparatus of the type disclosed in U.S. Pat. No. 2,656,508, it is capable of many uses. In medicine, biology, chemistry, and allied fields, research as well as routine testing required the use of apparatus which can produce fluid mixtures of specific concentrations accurately and automatically and particularly, can feed known quantities of fluids to a selected one of a plurality of locations.

In the apparatus referred to in U.S. Pat. No. 3,549,994, samples of whole blood were introduced one every fifteen seconds. The apparatus performs the requisite dilutions, tests, and computations needed for obtaining blood counts of white and red cells, a hematocrit determination, a hemoglobin measurement, and so on. Accordingly, such automatic instrument is required quickly and accurately to prepare the necessary sample suspensions of predetermined concentration for transfer to the testing apparatus of the instrument. Liquids must be pumped, transferred and moved between vessels and it is with such type of liquid transfer apparatus that this invention is concerned.

One type of the liquid transfer valve structure has been disclosed in U.S. Pat. No. 3,567,390 and that particularly consisted of a central element and a pair of outer elements engaged against opposite faces o the central element to sandwich same therebetween. The central element is movable relative to the other element between first and second positions. At least one measuring conduit is formed in the central element and at least a pair of ports are provided in each outer element. Each of the ports in one of the outer elements aligns with a port carried by other outer element so that two fluid paths are defined. The central member is indexed to a first position to align one measuring conduit with one of said fluid paths for reception in that one conduit of a portion of the fluid sample. The central element then is moved to a second position. By virtue of such movement, a quantity of the sample is segmented by means measuring conduit and deposited in the other fluid path for combining with a diluent introduced therein so as to deliver a precise dilution.

In the various fluid transfer valve constructions disclosed in the aforesaid patents, the segmenting passageways were oriented horizontally and further included associated therewith plural drive components that required maintenance of very close tolerances in manufacture. Failure to meet those close tolerances would result in either inaccurate alignment, movement, and the like, effecting the accurate measuring and transfer of the liquid. For example, when a leak formed in the valve, air may be drawn in with the sample being measured due to the vacuum associated with the drawing of the liquid sample. When to the extent that such air leaked replaces the volume that should be occupied by the liquid sample, the dilution ratio sought cannot be met and error results.

It would be desirable to permit such entrapped air to leave the segmented portion prior to the operation of the central element effecting such segmentation. If this is accomplished, then not only do proper dilution ratios occur but, much of the close tolerances mandatory in earlier valves may be relaxed since air leaking into the valve does not create erroneous measurements. Likewise, an arrangement that enables drainage under gravitational influence improves clearance of the valve passageways.

The trademark COULTER is a registered trademark, Registration No. 995,825, owned by Coulter Electronics, Inc. of Hialeah, Florida.

A liquid transfer valve for use in a diluting system and comprising a linearly movable valve element sandwiched between a pair of superposed parallel stationary elements for frictional movement therebetween, said stationary elements each having spaced sets of two parallel through passageways and said valve element having a pair of spaced parallel bores, said valve element being movable between a first position where said bores are aligned with one set of passageways and a second position where said bores are aligned with the other set of said passageways, and pneumatically operated drive means disposed on opposite ends of the valve element for driving same from one position to the other. Rail or restraining means are provided to limit the path of movement of said valve elements to a solely linear direction. Limit means which may include a pin and slot arrangement, are provided to control the extent of movement of said valve element properly to align the bores carried thereby with the appropriate set of passageways.

FIG. 1 is a diagrammatic representation of an automatic analysis apparatus employing the liquid transfer valve of the invention;

FIG. 2 is a perspective view of the liquid transfer valve of the invention;

FIG. 3 is a section taken along lines 3--3 of FIG. 2 and view in the indicated direction;

FIG. 4 is a fragmentary section taken along lines 4--4 of FIG. 3 and viewed in the indicated direction;

FIG. 5 is a top plan view of the valve of FIG. 2 with diagrammatic representation illustrating the conduit connections thereof to the automatic analysis apparatus;

FIG. 6 is a bottom view of the valve illustrated in FIG. 2 with diagrammatic representations of the conduit connections to the automatic analysis apparatus; and

FIG. 7 is an exploded view of the valve illustrated in FIG. 2 with some portions being shown in section to illustrate interior detail.

The fluid transfer valve construction in accordance with the herein invention is intended to function as a substitute valve for use in the diluting system such as employed in the apparatus disclosed in U.S. Pat. No. 3,549,994 granted Dec. 22, 1970 to Rothermel, et al. and is an improvement upon the fluid transfer valve structures disclosed in U.S. Pat., Nos. 3,567,389 and 3,567,390 issued to Coulter, et al. and to Rothermel respectively on Mar. 2, 1971, all three patents being owned by the assignee of the herein application. Reference can be made to these patents for a description of the general apparatus within which the fluid transfer valve of the invention is intended to operate and, as well to afford general information as to the functions which the transfer valve seeks to accomplish.

Accordingly, the specification of each of these patents respectively is incorporated herein to the extent required by one skilled in the art to understand the system and functions performed by the improved fluid transfer valve herein disclosed.

Generally, a fluid sample is obtained in any convenient manner. A tube or a snorkel is dipped into the sample and draws a quantity into the fluid transfer valve of the system. A minute measured part of the sample then is diluted with a predetermined quantity of diluent. The resulting suspension then is transferred to first testing apparatus of the automatic instrument wherein one or more tests or operations may be performed thereon. After the first test or series of tests are performed, a portion of the sample solution from said first testing apparatus again is drawn into the fluid transfer valve and a second dilution is performed by introduction of a predetermined quantity of diluent. The resulting suspension then is transferred to second testing apparatus where the required tests, etc., are performed.

In one embodiment of the invention disclosed herein, two diluting operations are employed and the resulting suspensions are tested by apparatus operating on the principle of U.S. Pat. No. 2,656,508. It should be understood that with regard to the instant invention, this is merely by way of illustration and does not so limit the present invention.

Looking now at FIG. 1, the diagram illustrates the general diluting system connected with testing apparatus. The liquid transfer valve assembly according to the invention is coupled into the system and designated generally by reference character 10. The representation of the liquid transfer valve 10 in FIG. 1 is diagrammatic, as will be explained hereinafter. The liquid transfer valve 10 is formed of three principal elements 12, 14 and 16 with the center valve element 14 sandwiched between the two outer elements 12 and 16. The center or sandwiched element 14 is slidably movable relative to the two fixed or stationary outer elements 12 and 16 to align certain passageways.

The sandwiched or central valve element 14 of valve assembly 10 is a carefully made and highly accurate rectangular structure having bores P9 and P10 arranged adjacent opposite lineal sides 18 and 20 respectively of the central element 14. Bores P9 and P10 are axially parallel one relative to the other with their central axes lying along a plane taken normal to said lineal sides 18 and 20 and located substantially midway between the opposite ends 22 and 24 of element 14. Each of these bores P9 and P10 is designed to carry a precise quantity or volume of some liquid, and upon movement between positions, here being two such positions, will slice off or subtend within itself the said volume of liquid and pass or transfer the same. This function is represented by the arrows showing the alignment of the center bores with the passageways carried by the sandwiching stationary elements 12 and 16 of the transfer valve 10.

The outer or sandwiching elements 12 and 16 of the valve 10 are similar in configuration, both being rectangular and of equal dimension, both lengthwise and width. The width of elements 12 and 16 is identical to the width of element 14 while the length of elements 12 and 16 is greater a predetermined amount than the length of element 14. Each of elements 12 and 16 have two pair or sets of passageways formed therein and extending through the thickness thereof. These are designated P1, P2, P3, P4 in element 12, and P5, P6, P7 and P8 in element 16. The elements 12 and 16 are arranged superposed between cylinder housing 26 and 28 with the center element 14 sandwiched therebetween, the elements being in face to face engagement and with element 16 being fastened at its respective ends to the housing 26, 28 by fastening means such as screws 30 while element 12 is secured in place by means to be described. When the elements 12, 14, and 16 are assembled passageways p1 and P5 are aligned coaxially, passageways P3 and P7 are aligned coaxially, passageways P2 and P6 are aligned coaxially, and passageways P4 and P8 are aligned coaxially. Passageways P1 and P2 have axes that lie in the same plane and likewise, passageways P3 and P4 have axes that lie in the same plane. The plane passing through the axes of passageways of P1 and P2 is normal to the opposite sides 18' and 20', and the plane passing through the axes of passageways P3 and P4 is parallel to the plane taken through the axes of passageways P1 and P2. The passageways P1 and P3 are aligned along the linear distance near side 18' and passageways P2 and P4 are aligned along the linear distance near side 20'. The linear distance between the axes of passageways P1 and P3 and the linear distance between the axes of passageways P2 and P4, of course, are identical. The same relationship also applies to the passageways P5, P6, P7, and P8 to the element 16. The linear distance between the axes of passageways P1 and P3, for example, can equal the difference in length of elements 12 and 16 as compared to the sandwiched element 14. The same distance is equal to the length of the path of travel of the central or sandwiched element 14 between its two positions. The first position of the element 14 occurs when passageways P9 and P10 are aligned respectively with passageways P1, P2, P5 and P6; the second position occurring when the passageways P9 and P10 are aligned with he passageways P3, P4, P7 and P8 respectively. Identical restraining rail pairs 32 and 34 are secured on opposite linear sides 18' and 20' of element 12 and 18" and 20" of element 16. Securement is effected by screws 36 or similar fastening means. Each of the guide rails have restraint portions 38 which serve to restrict the movement of element 14 solely to a linear direction.

Means are provided for coupling the sandwich of elements 12, 14 and 16 in assembly without interfering with the sliding movement of element 14. A hollow cylindrical post 40 is seated in a suitable passageway 41 formed in element 16 so that its axis is normal to the surface 16' of element 16. The post 40 has a through bore 42 and is located so that its axis is midway between the ends 22" anad 24" of element 16 and likewise is halfway between the opposite sides 18" and 20". The post 40 carries annular rings 44 and 46, the purpose of which will be explained hereinafter. A through slot 48 is formed in the movable element 14, the cross section of which is generally elliptical. The major axis of slot 48 is taken along a plane parallel to the opposite lineal walls 18' and 20' of element 14 while the minor axis is coplanar with the axes of passageways of P9 and P10. The center axis of slot 48 is aligned with the center axis of bore 42. When the center element 14 is arranged in face to face engagement with element 16, the post 40 passes through the slot 48 with the ring 44 within said slot. Ring 44 reduces the bearing area. The length of the slot 48 is selected so that the movement of element 14 in a linear direction is limited to the aforedescribed predetermined distance.

In the first position of element 14, the ring 44 is engaged against one end 50 of slot 48. The second position occurs when the ring 44 bears against the opposite end 52 of the slot 48. A cylindrical passageway 54 is formed in the element 12 at a location selected to align the axis of passageway 54 with the axis of the post 40 when the elements 12, 14 and 16 are assembled. The diameter of passageway 54 is slightly greater than the outer diameter of ring 46, said ring 46 being disposed within the passageway 54 when the elements 12, 14 and 16 are assembled. The length of the post 40 is selected so that a recess is defined at the mouth of passageway 54.

A rod 58 is provided with a threaded free end which is not shown and an enlarged knurled head 60. The opposite or lower end of the interior wall of bore 42 of cylindrical post 40 is provided with a threaded socket portion. The members 12, 14 and 16 coupled tightly in assembly by introducing rod 58 through passageway 54 into the bore 42 of cylindrical post 40 and threadably engaging the threaded lower end thereof with the threaded socket portion. A helical coil spring 62 is arranged with the rod 58 passing therethrough so that spring 62 is interposed between the undersurface of head 60 and the outer surface of element 12. A washer 63 completes the assembly. When the knurled head 60 is rotated to threadably engage the rod 58 with the threaded socket and tightened, bearing against spring 62, the assembly is completed. Suitable cylindrical couplers 64 are inserted in the respective passageways carried by elements 12 and 16 so that a portion thereof projects outwardly whereby to permit conduit connections to be made thereto.

The actuator or driving means for causing the movement of the control or sandwiched element 14 are contained in the cylinder housings 26 and 28. The bodies of cylinder housing 26 and 28 are rectangular with the facing walls 66, 68 thereof parallel. Each of the cylinder housings carry the same means for actuating the movement of the central sandwiched element 14. Referring to the left-handed housing 26 as viewed in FIGS. 2-4 and 7, a chamber 70 is formed in the housing 26 and has a generally cylindrical cross section. A piston 72 comprising a pair of nested cylindrical elements 74 and 76 sandwiching a rolling diaphragm 78 is arranged within the chamber 70 for movement therewithin under the influence of air pressure. The diaphragm 78 is of hatlike configuration with the rim 80 being positively held by cover plate 86 fastened to the housing 26 as by screws 88. The portions 76 and 74 of the piston which sandwich portion 80 of the rolling diaphragm 78 are maintained in assembly by screw 90 threadably engaged with plunger 92. The plunger 92 is seated in an axial passageway or socket 94 formed in the portion 76 of the piston 72.

The cover 86 carries a socket 96 which closes off the chamber 70. A seat 98 is formed in the socket to receive the head of screw 90. A suitable bore 100 communicating to the interior of socket 96 is formed in the cover 86 and a fitting 102 is inserted therein. A pair of angular passageways is formed in the cover and suitable fittings 104, 106, 108 and 110 are secured therein to establish communication with the passageways of the valve assembly by way of flexible conduits. Cover 86' secured thereto differs from cover 86 in that only three fittings are provided; cover 86' includes a Y or T bore whose entry is indicated by fitting 112 and whose pair of outlets is indicated by fittings 114 and 116. Passageways 118 and 120 are formed respectively in the walls 66 and 68 of housings 26 and 28 respectively to permit slidable passage therethrough of the plunger ends 122 and 124. Fittings 102 and 102' communicate with suitable passageways formed in the covers 86, 86' opening to the sockets 96, 96' thereof and are coupled to lines 97, 97' leading to a supply 99 of compressed air. Air is introduced alternatively into the sockets 96 or 96' driving the respective pistons 72 or 72' in cylinders 70, 70' and thus forcing the plungers 122 or 124 against the opposite ends respectively 22' and 24' of the sandwiched member so as to place said central element 14 in one or the other of said first and second positions.

As installed in the system represented diagrammatically in FIG. 1, there are fluid lines connecting the valve assemby with the other elements of the system and these fluid connections will be explained briefly in the following discussion.

It should be understood that the fluid lines will effectively pass through pump means and control valve means some of which are not shown in the drawing. Fluid line 120 leads from the sample snorkel 122 to the passageway P8. The snorkel 122 is introduced into sample container 123.

Fluid line 126 connects the diluent supply and dispenser 128 to the fitting 112. Flexible conduit 130 couples fitting 114 to passageway P3 and flexible conduit 132 couples fitting 116 to passageway P2. Thus, passageway P3 and passageway P2 are coupled to the diluent dispenser 128. Fluid line 134 connects the white cell mixing chamber thief 136 to the passageway P5.

Fluid line 138 connects passageway P6 with the white cell mixing vessels 140 and 140'.

Fluid line 142 connects passageway P7 with the red cell mixing vessels 146 and 146'.

Fluid line 148 connects passageway P8 to waste or back to the snorkel 122 (see broken line representation 148' for rinsing thereof into a backwash receptacle 125 in broken line representation.

Fitting 106 is coupled to an alternative pressure vacuum source 150 by line 152 and by way of T connection 154 to another pump and source of diluent, both indicated by 156 to provide for the rinsing or backwash.

Fitting 104 is coupled to vacuum/pressure source 150 by line 158.

There are occasions when the elements 12 and 14 are disassembled from the assembly 10 to gain access to the bearing surfaces. Proper reassembly is essential and for that purpose, guide means are provided which comprise an upstanding post 160 secured to outer valve element 16 parallel to post 40 but offset therefrom. A narrow slot 162 is formed in the sandwiched element 14 and a socket 164 is formed in element 12 aligned with the post 160 so as to receive the same after post 160 passes through slot 162. The slot 164 generally is longer than the linear stroke of the element 14.

Sides 18 and 20 of the sandwiched element 14 may be provided with a wear resistant or antifriction hard faced ceramic coating designated by reference character 166 and, the same coating can be provided on the bearing surfaces of elements 12, 14 and 16 surrounding the respective passageways as represented by reference character 168.

Reference now will be directed to the operation of the diluting system so that the functions performed by the valve 10 is clearly understood.

If it is assumed that the transfer valve 10 is in the condition shown in FIG. 1 with the center element 14 disposed so that the solid line portions of conduits P9 and P10 are on the right are aligned with the passageways shown, a quantity of liquid sample S is drawn by snorkel 122 from container 123 into line 120 into aligned passageways P8, P10 and P4. The raw sample S fills the passageway P10. Then the center element 14 is moved to its alternate position (to the left as illustrated in FIG. 1), represented by the broken line position of the passageways P9 and P10, the volume of sample subtended will be aligned with the passageways P2 and P6.

Prior to the movement of the center element 14 to its second position, the solid portion of element 14 prevents communication between passageways P5 and P1. After movement to the left the center element is completed, then passageway P10 is aligned with passageways P2 and P6 and diluent automatically is dispensed through then aligned passageways P2, P10 and P6 to dispense a predetermined volume of diluent with the subtended volume of sample S to vessels 140 and 140' by use of line 138 where the first dilution or sample suspension of a predetermined concentration are made into vessels 140 and 140'.

Pump 150 then operates to draw fluid from chamber 140' by way of thief 136 along line 134 to passageway P5 and through passageway P9 and out from passageway P1.

A small part of the diluted sample that is withdrawn or thiefed from vessel 140' is contained in the passageway P9 at position 2. When the center element is indexed back to position 1, which realigns conduit P10 with passageways P8 and P4, a volume or plug of the first dilution is subtended and deposited in the flow path of the then aligned passageways P3 and P7, leading to the vessels 146 and 146'.

As is evident, a predetermined volume of raw sample is subtended in passageway P10 and a given volume of first dilution of the sample later is delivered. to vessels 146 and 146' when the center element is moved from position 2 to position 1. At position 2, the subtended volume of raw sample is delivered to vessels 140 and 140' and thereafter the said first dilution of said raw sample is withdrawn from vessel 140 and fed to passageway P9 for later subtention and delivery.

All aspiration of samples is directed upwards of the valve passageways and all delivery is performed under the influence of gravity. Thus any entrapped air is permitted to rise from the measuring passageways P9 and P10 while drainage is under gravitational influence.

It should be understood that variations in the construction of the transfer valve of the invention are contemplated without departing from the scope of the invention as claimed.