DK147844B

DK147844B - PROCEDURE FOR REPRODUCABLE DELIVERY OF SMALL LIQUID QUANTITIES BY HELPING A MICRO PUMP PUMP

Info

Publication number: DK147844B
Application number: DK356980AA
Authority: DK
Inventors: Bernd Zierenberg
Original assignee: Boehringer Sohn Ingelheim
Priority date: 1979-08-20
Filing date: 1980-08-19
Publication date: 1984-12-24
Also published as: NO155358C; CA1152379A; IL60854A0; NO802439L; ES8105829A1; DK356980A; EP0024313B1; ZA805103B; FI67434C; NZ194707A; IE50187B1; AU544213B2; ES494358A0; DK147844C; IE801752L; ATE4290T1; NO155358B; FI67434B; AU6156880A; DE2933617A1

Abstract

1. Process for metering small quantities of liquid without leaving a residue by means of a micro-piston pump having a capillary cylinder in which a piston, which fits in gastight manner therein, is mounted so as to be movable between a top dead centre and a bottom dead centre, the cylinder at its end located opposite the base of the piston opening into a twoway valve which connects the space in the cylinder alternately to an inlet and to an outlet (which connects the cylinder to the atmosphere during the first stage of the intake operation), characterised in that the piston and the valve are moved in such a way that, during the intake operation, first a defined quantity of air and then a defined quantity of liquid is transported into the cylinder, the quantity of air being such that, as the piston moves downwards to bottom dead centre, all the liquid is expelled through the outlet line.

Description

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Opfindelsen angår en fremgangsmåde til reproducerbar afgivelse af en lille væskemængde ved hjælp af en mikrostempelpumpe, der har en kapillar cylinder, hvori et gastæt indpasset stempel er anbragt bevægeligt mellem 5 et øvre og et nedre dødpunkt, og hvor cylinderen ved sin over for stempelbunden liggende ende udmunder i en tovej sventil, der forbinder cylinderhulrummet skiftevis med et indløb og et udløb.BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for reproducibly delivering a small amount of fluid by means of a micro-piston pump having a capillary cylinder in which a gas tightly fitted piston is movably disposed between an upper and a lower dead center and the cylinder at its opposite end to the piston bottom. culminate in a two-way swivel connecting the cylinder cavity alternately with an inlet and an outlet.

Mikrostempelpumper, der er indrettet til udtagning 10 af små væskevolumener fra et reservoir og doseret afgivelse af disse volumener, har den ulempe, at væskemængden, der transporteres for hvert slag, svinger stærkt.Micro plunger pumps adapted to take 10 small volumes of liquid from a reservoir and dispense these volumes have the disadvantage that the amount of liquid transported for each stroke fluctuates strongly.

Grunden til dette er, at der til pumpens indervægge klæber væskerester, som ikke løber med ud.The reason for this is that liquid residues, which do not run out, adhere to the pump's inner walls.

15 Bestemmende for disse mangler er forholdet mellem væskevolumenet, der afmåles med et slag, og den inder-flade af pumpen, som vædes af væsken. Ved små volumener bliver forholdet mellem væskevolumenet og pumpens inder-flade særlig ugunstigt, og væskemængden, der afgives for 20 hvert stempelslag, er ikke mere reproducerbar.Determining these deficiencies is the ratio of the fluid volume measured with a stroke to the inner surface of the pump wetted by the liquid. At small volumes, the ratio of the fluid volume to the inner surface of the pump becomes particularly unfavorable, and the amount of fluid delivered for each piston stroke is no longer reproducible.

Ved doseringen af lægemiddelopløsninger virker de væskerester, der bliver tilbage i pumpen, særligt forstyrrende, fordi de kan tjene som grobund for bakterier og andre infektionskim, især hvis udløbet står i åben 25 forbindelse med ikke-sterile omgivelser.When dosing drug solutions, the residual fluid left in the pump seems particularly disruptive because it can serve as a breeding ground for bacteria and other germs of infection, especially if the outlet is in open connection with non-sterile environments.

Med udgangspunkt i de indledningsvis omhandlede foranstaltninger har opfindelsen til formål at angive en sådan fremgangsmåde til reproducerbar afgivelse af små væskemængder ved hjælp af en mikrostempelpumpe, hvor 30 væskemængden, der transporteres under et stempelslag, uddrives fuldstændigt.The object of the invention is to provide such a method for reproducible delivery of small amounts of liquid by means of a micro-piston pump, in which the quantity of liquid transported under a piston stroke is completely expelled.

Til opnåelse heraf er fremgangsmåden ifølge opfindelsen ejendommelig ved, at indsugningsprocessen udføres i to trin, hvor stempelslaget og ventilstillingen er ko-35 ordineret således, at der i det første trin - via udløbet, der er forbundet med atmosfæren, indsuges en defineret luftmængde, og i det andet trin - via indløbet 2 147844 indsuges en defineret væskemængde, hvorhos luften, der indsuges i det første trin, af kapillarkræfter holdes i cylinderen, og volumenet af den indsugede luftmængde i det mindste svarer til dødvolumenet af cylinderen, ven-5 tilen og udløbet.To achieve this, the process according to the invention is characterized in that the suction process is carried out in two stages, where the piston stroke and the valve position are coordinated so that in the first step - through the outlet connected to the atmosphere, a defined amount of air is sucked in, and in the second stage - via the inlet 2 147844, a defined amount of liquid is drawn in which the air drawn in the first stage is held by capillary forces in the cylinder and the volume of the suctioned air volume at least corresponds to the dead volume of the cylinder, the valve and expired.

Fremgangsmåden ifølge opfindelsen kan f.eks. anvendes med fordel til tilførsel af en defineret mængde stof, såsom medicin, til forstøverpladen i en piezoelektrisk forstøver, såsom den forstøver, der er kendt fra DE-frem-10 læggelsesskrift nr. 2.537.765.The method according to the invention can e.g. is advantageously used to supply a defined amount of substance, such as medicine, to the nebulizer plate of a piezoelectric nebulizer such as the nebulizer known from DE-Publication No. 2,537,765.

Fra US-patent nr. 3.299.827 kendes der en pumpe, der er egnet til dosering af væsker af forskellig art.US Patent No. 3,299,827 discloses a pump suitable for dispensing liquids of various kinds.

I modsætning til, hvad der gør sig gældende ved mikro-stempelpumpen, der anvendes til udøvelse af fremgangs-15 måden ifølge opfindelsen, har den kendte pumpe dog ikke en kapillar cylinder og opererer ej heller med en sådan styring, at der før indsugningen af væsken suges en defineret mængde luft ind i cylinderen.However, contrary to the micro-plunger pump used in the practice of the invention, the known pump does not have a capillary cylinder nor does it operate with such control that prior to suction of the liquid a defined amount of air is sucked into the cylinder.

Fra DE-patent nr. 254.111 kendes der en pumpe, der 20 er dimensioneret større, og som f.eks. kan anvendes til brændstoftilførsel. Denne kendte pumpe har imidlertid heller ikke en kapillar cylinder, og der forudses ej heller, at der ved dens betjening skal anvendes luft som hjælpemiddel for at sikre en fuldstændig udtømning.From DE-Patent No. 254,111, a pump is dimensioned 20 which is larger in size and which e.g. can be used for fuel supply. However, this known pump does not have a capillary cylinder, nor is it envisaged that in its operation, air must be used as auxiliary to ensure complete discharge.

25 Mikrostempelpumpen ifølge opfindelsen består i ho vedsagen af en kapillarlignende cylinder med et gastæt indpasset stempel, en tovejsventil med indløbs- og udløbsledning ved den over for stempelbunden liggende ende af cylinderen, og eventuelt en styreindretning, som ko-30 ordinerer stempelbevægelsen og ventilindstillingen.The micro-piston pump according to the invention consists mainly of a capillary-like cylinder with a gas-tight piston, a two-way valve with inlet and outlet conduit at the opposite end of the cylinder, and optionally a control device which coordinates the piston movement and the valve setting.

Mikrostempelpumpen ifølge opfindelsen tjener fortrinsvis til dosering af væskemængder i området fra 10 til 50 μΐ, men kan ved ændring af dimensionerne også indrettes til større eller mindre volumener. Ved anven-35 delse af en tilstrækkeligt snæver cylinder sørges der for, at der som følge af kapillariteten - også ved beliggenhed sændringer af den fyldte mikrostempelpumpe 3The micro-plunger pump according to the invention preferably serves for dosing liquid quantities in the range of 10 to 50 µΐ, but can also be adjusted to larger or smaller volumes by changing the dimensions. By using a sufficiently narrow cylinder, it is ensured that due to the capillarity - also at location changes of the filled micro piston pump 3

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sikres opretholdelse af luftsøjlen mellem stemplet og væsken.ensure the maintenance of the air column between the piston and the fluid.

Herved skabes der sikkerhed for, at der til enhver tid befinder sig en luftpude over den indsugede væske-5 mængde, og at der under stemplets nedadbevægelse - først undviger væske og derpå det over denne stående luftvolumen gennem udløbet. Luftpuden, der følger væskevejen, bevirker en fuldstændig uddrivning af væsken fra cylinderen og pumpens ventilområde. Der klæber ingen eller 10 kun yderst små væskemængder til pumpens indervægge, og der kan følgelig med et stempelslag på reproducerbar måde transporteres en defineret mængde væske.This ensures that there is at all times an air cushion over the suctioned liquid volume and that during the downward movement of the piston - liquid is first avoided and then over this standing air volume through the outlet. The air cushion that follows the fluid path causes a complete expulsion of the fluid from the cylinder and pump valve area. No or only very small quantities of liquid are adhered to the inner walls of the pump and consequently a defined amount of liquid can be transported by a piston stroke in a reproducible manner.

Luftvolumenet, der indsuges i det første trin, er dimensioneret således, at det i det mindste svarer til 15 dødvolumenet af cylinderen, ventilen og udløbet. Med denne luft kan der under pumpens operering ske fuldstændig uddrivning af væsken fra cylinderen, ventilen og udløbet .The volume of air drawn in the first stage is sized to at least correspond to the dead volume of the cylinder, valve and outlet. With this air, during operation of the pump, the liquid from the cylinder, valve and outlet can be completely expelled.

Opfindelsen forklares nærmere i det følgende under 20 henvisning til tegningen, hvor fig. 1 viser i vertikalsnit en typisk udførelsesform for mikrostempelpumpen ifølge opfindelsen i udgangsstilling, fig. 2 i vertikalsnit mikrostempelpumpen i fyldt 25 stand, og fig. 3 et brudstykke af mikrostempelpumpens nedre parti i snit vinkelret på snittet i fig. 1.The invention will be explained in more detail below with reference to the drawing, in which 1 shows in vertical section a typical embodiment of the micro-piston pump according to the invention in the starting position; FIG. 2 in vertical section, the micro plunger pump in full condition; and FIG. 3 is a fragmentary sectional view of the lower portion of the micro piston pump perpendicular to the section of FIG. First

Den på tegningen viste mikrostempelpumpe har et stempel 1, der fortrinsvis består af specialstål, og 30 som bevæger sig i en meget snæver cylinder 2, der f.eks. kan være udført af glas eller metal. Cylinderen ender i en ventilblok 4, der f.eks. kan bestå af et formstof, såsom teflon, og hvori der er anbragt en gastæt sluttende ventilglider 5, der fortrinsvis består 35 af specialstål, og som kan bevæges til anlæg mod et anslag 6; 7. Ved anbringelse af en indsnøring 8 i ventilglideren 5, ud for et indløb 9 respektive ud- 4 147 84 4 løb 10, opnås der forbindelse mellem indløbet 9 respektive udløbet 10 og et hulrum 11 i cylinderen 2.The micro-piston pump shown in the drawing has a piston 1, which preferably consists of special steel, and 30 which move in a very narrow cylinder 2, e.g. may be made of glass or metal. The cylinder ends in a valve block 4 which e.g. may consist of a resin such as Teflon and in which is arranged a gas tight closing valve slider 5, which preferably consists of special steel and which can be moved to abut an impact 6; 7. By placing a lanyard 8 in the valve slider 5, next to an inlet 9 and outlet 10 and outlet 10 respectively, a connection is obtained between the inlet 9 and the outlet 10 and a cavity 11 in the cylinder 2.

Stemplet 1 befinder sig i sit nedre dødpunkt, når et stempelgreb 12 støder mod cylinderen 2. Produktet af 5 cylinderens lysningstværsnit og slaget mellem mærker a og c bestemmer doseringen.The piston 1 is at its lower dead center when a piston grip 12 abuts against the cylinder 2. The product of the cylinder cross section and the stroke between marks a and c determines the dosage.

Bevægelsen af stemplet 1 og ventilglideren 5 er styret på en sådan måde, at der opnås følgende bevægelsesforløb : 10 a) Ved åbnet udløb (anslag 7 ligger an mod ventil blokken 4) bevæger stemplet 1 sig fra stillingen i fig. 1 i retning A, indtil der er indsuget en bestemt mængde luft i cylinderen (stemplets endeflade befinder sig ved mærket a). Luftmængden er afpasset således, at 15 man ved udtømning af mikrostempelpumpen får sikkerhed for, at luftmængden driver al væske via ventilen ud gennem udløbsledningen.The movement of the piston 1 and the valve slider 5 is controlled in such a way that the following movements are achieved: 10 a) At the open outlet (stop 7 abuts the valve block 4) the piston 1 moves from the position in fig. 1 in direction A until a certain amount of air is sucked into the cylinder (the end face of the piston is at the mark a). The airflow is adjusted so that when the micro-plunger pump is emptied, it is ensured that the airflow delivers all the liquid via the valve through the outlet pipe.

b) Under det andet trin bevirkes der ved forskydning af ventilglideren i retning D frem til anslaget 20 frigivelse af forbindelsen mellem indløbet 9 (og dermed forrådsbeholderen) og cylinderen.b) During the second step, by the displacement of the valve slider in direction D up to the stop 20, the connection between the inlet 9 (and thus the storage container) and the cylinder is released.

c) Stemplet 1 bevæges videre i retning A, indtil der er indsuget det af slaget og cylindertværsnittet fastlagte væskevolumen (endestilling ifølge fig. 2; 25 stemplets endeflade befinder sig ved mærket c).c) The piston 1 is moved further in direction A until the liquid volume determined by the stroke and the cylinder cross section is sucked in (end position according to Fig. 2; the end surface of the piston is at the mark c).

d) Ventilglideren 5 tilbagestilles i retning C til anlæg mod anslaget, hvorved der er åbnet for forbindelsen mellem cylinderen 2 og udløbet 10.d) The valve slider 5 is reset in direction C to abut the stop, thereby opening the connection between the cylinder 2 and the outlet 10.

e) Stemplet 1 bevæger sig frem til det nedre død- 30 punkt (stilling ifølge fig. 1), hvorved først væsken og derefter luften fortrænges ud fra cylinderen 2 og drives ud gennem udløbsledningen. Luften benyttes til fri-blæsning af ventilen og udløbsledningen. Efter denne udtømningsproces er udgangsstillingen atter opnået.e) The piston 1 moves to the lower dead center (position of Fig. 1), whereby first the liquid and then the air is displaced from the cylinder 2 and driven out through the outlet line. The air is used for free-blowing of the valve and the discharge line. After this depletion process, the starting position is again achieved.

35 Styringen af det beskrevne bevægelsesforløb kan i det enkleste tilfælde ske manuelt. Der kan imidlertid også anvendes kendte mekaniske eller elektriske midler.35 In the simplest case, control of the described course of movement can be done manually. However, known mechanical or electrical means may also be used.

Claims

A simple device for this purpose consists of a combination of cogs, gears and weights, constructed as follows: Four gears are arranged side by side and connected 5 rigidly to each other. The circumference of the gears is only partially filled with teeth, ie. in such a way that, in the main, only one cog becomes effective at a particular time. While e.g. the first sprocket via a rack and lever causes the process a), the three other 10 sprockets run freely until the desired amount of air enters the cylinder. The second sprocket then provides for adjustment of the valve slide, while the first sprocket simultaneously moves the piston towards the upper dead center. Then, the first 15 sprockets run freely, while the third sprocket brings the valve slide into the outlet position. The fourth gear with associated transmission elements then becomes effective, thereby bringing the piston to the lower dead center. The steering mechanism is arranged so that all 20 elements are again in the starting position when the gears have a 360 ° turn. In another embodiment of the control device, the pivoting movement is replaced by an upward and downward movement.

In this embodiment, it may be advantageous as long as the cylinder and valve are arranged such that the directions of movement of the piston and valve slider extend in parallel. A method for reproducible delivery of a 3 small amount of liquid by means of a micro piston pump 4 having a capillary cylinder in which a gas tightly fitted piston is movably disposed between an upper and a lower dead center, and wherein the cylinder at its opposite end to the piston bottom opens into a two-way valve connecting the cylinder cavity alternately with an inlet and