WO2013159791A1

WO2013159791A1 - Metering device, counting device, metering process and counting method

Info

Publication number: WO2013159791A1
Application number: PCT/EP2012/001786
Authority: WO
Inventors: Robert Rieger
Original assignee: Testo Ag
Priority date: 2012-04-26
Filing date: 2012-04-26
Publication date: 2013-10-31

Abstract

In a metering method for providing a metered quantity of a liquid the invention proposes forming an inlet opening (3), an outlet opening (4) and a porous wall region (8) with an external removal opening (9) on a metering chamber (5), and applying a first pressure difference between the inlet opening (3) and the outlet opening (4) in order to transport a liquid from a reservoir (12), externally connected to the inlet opening, to the outlet opening (4), and at the same time applying a second pressure difference between the removal opening (9) and the inlet opening (3) in order to divert some of the liquid (7), which is flowing in through the inlet opening, via the porous wall region (8) out of the metering chamber (5) until the reservoir (12) and the metering chamber (5) are emptied, wherein the metered quantity of the liquid has exited the outlet opening (4) and is in readiness after termination of the process.

Description

Metering device, counting device, dosing method and counting method

The invention relates to a metering device having a metering chamber having an inlet opening and an outlet opening, wherein a first means for applying a first pressure difference between the inlet opening and the outlet opening is formed in order to meter a quantity of a liquid flowing through the inlet opening through the metering chamber to promote the outlet opening. The invention further relates to a counting device for determining a volume-related or absolute number of particulate constituents in a liquid.

The invention further relates to a metering method for metering a liquid, wherein a first pressure difference between an inlet port and an outlet port of a metering chamber is applied to promote a metered amount of a liquid flowing through the inlet port through the metering chamber to the outlet port.

Finally, the invention relates to a counting method for determining a volume-related or absolute number of particulate constituents in a liquid. There are metering devices are known in which the amount to be metered is determined by the volume of the metering chamber. In these metering devices, the metering chamber is completely filled with the liquid, and the amount to be metered results from removal of the contents held in the dosing chamber. In this case, it is necessary to monitor the complete filling of the metering chamber and the complete emptying in order to actually obtain the metered amount.

There are further metering devices are known in which the amount to be metered is formed by clocked valves. In these metering devices, an amount to be metered can be determined by the clocked valves are opened at a known volume flow of the liquid in a predetermined time interval. In order to actually determine the defined amount, a precise adjustment of the pressure difference or a measurement of the volume flow is required. The invention has for its object to achieve a dosage of a liquid with the least possible expenditure on equipment.

In order to achieve this object, it is proposed according to the invention that the metering chamber has a porous wall area, that the porous wall area forms a removal opening on the outside and that a second means for applying a second pressure difference between the removal opening and the inlet opening forms is to branch off a portion of the liquid flowing through the inlet opening through the discharge opening. The advantage here is that a delimited, unknown volume of a liquid of the dosing chamber can be fed through the inlet opening, wherein in an intermediate state in the promotion of the inflowing liquid through the metering an equilibrium state between the inflowing liquid and the branched off through the removal opening liquid can be achieved which the unknown Volume reduced to a well-defined amount of liquid in the dosing. Thus, metering can be done without active control and no moving parts such as timed valves and the like are needed. Any liquid volume can be reduced to a given volume if it is sufficiently larger than this predetermined volume. More specifically, it may be provided that the input volume is greater than the predetermined volume plus an amount that is exhausted through the porous wall portion. The invention has the further advantage that no monitoring by sensors and no active influence on the volume flow of the liquid through the metering chamber is required. Thus, the expenditure on equipment for dosing is very low. Preferably, the porous wall region is arranged in the flow or conveying direction between the inlet opening and the outlet opening.

In one embodiment of the invention, it can be provided that the inlet opening is connected to a delimited or delimitable reservoir. The advantage here is that a definable volume of liquid can be fed, which according to the invention can be reduced to the predetermined volume.

It is preferably provided that this predetermined volume and in particular the amount to be metered is smaller than a volume of the metering chamber. In contrast, the amount supplied through the inlet opening can be of any desired size, in particular greater than the predetermined volume plus the quantity extracted during operation by the porous wall region.

A porous wall region is understood as meaning a wall region which has pores traversing the wall, wherein the pores are preferably dimensioned such that capillary effects occur and / or the pores remain filled with liquid due to the capillary effect, even if the dosing chamber is emptied. Preferably, the porous wall portion is formed of a material which is wetted by the liquid to be metered. This may be due to the fact that the porous wall area has a contact angle of less than 90 ° with this liquid. For example, in the case of water, the porous wall region may be formed as a hydrophilic membrane, in the case of non-polar liquids as a hydrophobic membrane. The pore size here can regulate the strength of the capillary effect with which the liquid is retained in the pores. For example, the smaller the pores are, the more pressure has to be applied to deflate the pores.

With the outside training of the removal opening is reached that the Entnahmeöff is separated by the porous wall portion of the dosing. Thus, with the second pressure difference, a removal of the part of the liquid flowing through the inlet opening through the porous wall area can be effected.

The porous wall area and / or the metering chamber can / can be made for example by injection molding or hot stamping. Elaborate post-processing steps after production are not required.

It can also be provided that the porous wall region is formed by a preferably hydrophilic membrane. This is favorable, for example, if the liquid is an aqueous (polar) solution. It can also be provided that the porous wall region is formed by a hydrophobic membrane. This may be advantageous, for example, if the liquid is a non-polar solution.

In one embodiment of the invention, it may be provided that the porous wall region extends over a length of the metering chamber between the inlet opening and the outlet opening. The advantage here is that the metering chamber is dimensioned as small as possible. It is further achievable that the inflowing liquid contacts or covers an increasing proportion of the porous wall area as the metering chamber is filled, whereby an ever greater proportion of the liquid flowing through the inlet opening can be branched off through the removal opening. It can also be provided that the porous wall region extends over a circumference of the metering chamber which surrounds a connecting line between the inlet opening and the outlet opening. It is advantageous in this case that portions of the liquid flowing through the inlet opening can be branched off on all sides transversely to the connecting line. In this way, the length of the porous wall region along the connecting line between the inlet opening and the outlet opening is as low as possible. Thus, a minimum dimensioning of the metering chamber can be achieved.

In one embodiment of the invention can be provided that on the outside of the porous wall portion, a receiving space is formed. The advantage here is that the diverted part of the inflowing liquid can be absorbed over a longer period.

It is particularly favorable if the receiving space is filled with a liquid-absorbing, air-permeable material. The advantage here is that the applied second pressure difference can be applied independently of the level of the receiving space. For example, the material may be a superabsorbent polymer.

In the embodiment of the invention can be provided that a pore size and a choice of material are tuned to the second pressure difference, that the second pressure difference is smaller than a capillary pressure in the porous wall region. The advantage here is that then the second pressure difference is not sufficient to empty the pores of the porous wall portion of liquid when the inner portion of the metering chamber is free of liquid. Thus, it can be achieved in a simple manner that the porous wall area is hermetically sealed when the filling chamber is empty or empty.

Generally it can be provided in embodiments of the invention that the first means comprises a device for generating a negative pressure which is connected to the outlet port or connectable.

For example, in an embodiment of the invention, it may be provided that the device for generating a negative pressure is set up by an evacuated chamber, a centrifuge or vessels arranged at different heights.

In one embodiment of the invention can be provided that the first means comprises a first pump which is connected to the outlet opening. The advantage here is that a negative pressure can be applied, with which the inflowing liquid is conveyed. In general, in embodiments of the invention it can be provided that the second means has a device for generating a negative pressure, which is connected to the Entnahrneöfnung. For example, this may be a centrifuge, an evacuated chamber, or containers or the like arranged at different heights may be formed.

It can be provided that the device for generating a negative pressure of the first means is formed separately from the device for generating a negative pressure of the second means, or that the device for generating a negative pressure of the first means identical to the device for generating a negative pressure of the second Means is.

In further embodiments, the first means for applying a first pressure difference and / or the second means for applying a second pressure difference can have a device for applying an overpressure to the inlet opening.

In one embodiment of the invention can be provided that the second means comprises a second pump which is connected to the removal opening. The advantage here is that a negative pressure with respect to the inlet opening at the removal opening can be applied, with which liquid from the metering chamber can be conveyed through the porous wall area.

It is particularly favorable if the first pump and the second pump are identical. The advantage here is that only one pump is required. Pressure fluctuations due to uneven operation of the pump thus do not or only slightly affect the operation of the metering device. It can also be provided that the first pressure difference is equal to the second pressure difference. The advantage here is that pressure fluctuations that can occur in an applied vacuum, compensate each other.

In one embodiment of the invention it can be provided that a length of the porous wall region along a connecting line between the inlet opening and the outlet opening is tuned to the first pressure difference and the second pressure difference in such a way that at a predetermined filling level of the dosing chamber equilibrium between a per Time unit is set by the inlet opening entering amount of liquid and a branched off in the time unit by the discharge opening liquid amount until a connected externally to the inlet opening reservoir is emptied. In this case, with the first pressure difference, the metering chamber can be filled with liquid, while the second pressure difference causes a removal of liquid from the metering chamber via the porous edge region and the removal opening. The amount of liquid removable per unit of time from the discharge opening depends on the second pressure difference and the size of the area of the porous wall area which is in contact with the liquid in the pressure chamber. The larger this area, the more amount of liquid can be removed per unit of time. If the length of the porous wall region along a connecting line between the inlet opening and the outlet opening chosen sufficiently large, so an equilibrium state can be achieved, through which the entire inflowing

Amount of liquid can be discharged through the discharge opening. Thus, it can be achieved that excess liquid in the reservoir can be removed independently of the initial volume of liquid without having to monitor a quantity of liquid or a period of time. In one embodiment of the invention, it may be provided that the first pressure difference is matched to the second pressure difference such that when the reservoir is empty, an amount of liquid in the dosing chamber can be transported at least partially to the outlet opening. Here, the first pressure difference causes a promotion of liquid in the metering chamber to the outlet opening, while the second pressure difference causes a promotion of liquid from the metering chamber through the porous wall area. Increasing the first pressure difference causes more fluid to be transported to the outlet port. Increasing the second pressure difference, on the other hand, causes more liquid to be removed through the porous wall area. In a certain range of the ratio of the first pressure difference to the second pressure difference, a defined proportion of an amount of liquid in the metering chamber can thus be transported away through the outlet opening. Thus, it can be achieved that a defined proportion of a quantity of liquid reduced to a predefined volume from the dosing chamber can be discharged through the outlet opening.

According to the invention, the metering device according to the invention can be used in a counting device described above, in which a metering device according to the invention, in particular as described above and / or according to one of claims 1 to 9, is provided, wherein a measuring device is connected to the outlet opening of the metering device, wherein the measuring device for measuring a measured variable which is dependent on the number of particulate constituents in a liquid emerging from the outlet opening of the metering device. The advantage here is that with the metering a defined amount to be dosed Liquid can be provided, at which a volume-related number and / or a total number in a total amount of liquid supplied particulate components is measurable.

To determine the absolute number it can be provided that the porous wall area is impermeable to the particulate components. Thus, a concentration of the particulate components in the metering chamber is feasible, in particular before the count of the particulate components.

By way of example, the measured variable may include an intensity of a scattered light and / or a proportion of polarized radiation in a specific manner and / or another physical measured variable, for example using a method from the group of transmitted light methods, scattered light methods, fluorescence methods for characterizing the number of particulate components in one Liquid is measurable, be. To achieve the above object is proposed according to the invention in a metering of the type described above, that the metering chamber has a porous wall portion with a removal opening formed on the outside of the porous wall region and that during the promotion of the liquid from the inlet opening to the outlet opening, a second pressure difference between the Inlet opening and the discharge opening is applied to divert a portion of the liquid flowing through the inlet opening via the discharge opening from the metering chamber. In this case, the branching via the removal opening preferably takes place continuously. The advantage here is that a balance, which at a certain level of the metering chamber between the inflowing through the inlet opening liquid and on the Entnahmeöff- adjusting the liquid withdrawn or branched off, can be used to reduce an unknown volume of liquid supplied via the inlet opening to a defined volume.

To delimit the total volume of liquid supplied, it may be provided that the liquid is conveyed from a reservoir connected to the inlet opening into the metering chamber. In this case, the reservoir can be delimited or delimited in the sense that the volume of liquid provided in the reservoir is delimited from the environment. The exact amount of liquid volume provided need not be known. In one embodiment of the invention can be provided that the process is terminated when the reservoir and / or the metering chamber is empty / are.

The advantage here is that no additional termination criterion must be monitored. Since the process terminates by itself when the reservoir and the metering chamber are emptied and thus no further liquid of the outlet opening is supplied and is supplied. In one embodiment of the invention it can be provided that in a first partial step, the metering chamber is filled through the inlet opening to a predetermined level. The advantage here is that a portion of the porous wall area is defined by the predetermined level, which is in contact with the liquid. This proportion specifies how much liquid can be branched off via the removal opening. Preferably, therefore, the predetermined level is set so that a proportion of the porous wall area with the liquid in the metering chamber is covered or in contact, and another portion of the porous wall portion not.

However, it can also be provided that the predetermined fill level is selected such that the porous wall area is completely covered or in contact with liquid in the metering chamber.

In one embodiment of the invention, it may be provided that in a second sub-step, an amount of liquid entering through the inlet opening per unit of time is completely removed or drawn off through the removal opening until a reservoir connected to the inlet opening is emptied. It is preferably provided here that the second sub-step follows the mentioned first sub-step and / or that the second sub-step is executed when the metering chamber is filled with liquid up to or a predetermined level. The adjustment of the described balance between the amount of liquid entering and the amount of liquid discharged through the withdrawal opening advantageously causes an unknown volume of liquid to be reduced until the reservoir is deflated. This ensures that the amount of liquid present in the metering chamber at the end of the second substep is independent of the volume of liquid originally present in the reservoir.

In one embodiment of the invention, provision may be made for a quantity of liquid located in the metering chamber to be partially diverted through the removal opening and partially transported in the metering chamber to the outlet opening, a total quantity of liquid transported to the outlet opening being measured as a metered quantity of the liquid. provided. It is preferably provided here that the third sub-step follows the already described first or second sub-step and / or that the third sub-step is carried out after the reservoir or a reservoir connected to the inlet opening has been emptied. This refinement of the third sub-step offers the advantage that a volume of liquid reduced in the metering chamber to a defined amount can be dissipated proportionally from the outlet opening. Thus, the dosed amount desired in the dosing process can be readily provided without the need for additional equipment.

In one embodiment of the invention, it can be provided that the portion of the liquid branched off through the porous wall region is received outside the removal opening by an absorbent, air-permeable material. The advantage here is that the second pressure difference can be maintained in a simple manner regardless of the amount of liquid withdrawn through the removal opening. It is preferably provided that the material is a superabsorbent polymer.

In one embodiment of the invention can be provided that the second pressure difference is set equal to the first pressure difference. The advantage here is that the appra- rative effort for the implementation of the dosing is again reduced. Another advantage is that fluctuations in the pressure differences provided compensate automatically. In one embodiment of the invention can be provided that the second pressure difference is set smaller than a capillary pressure in the porous wall area. The advantage here is that the porous wall area even with emptied Dosierkam- remains air impermeable. Thus, it is avoidable that the porous wall portion may become permeable to air at an end of an amount of liquid located in the metering chamber at an inlet opening, whereby the first pressure difference would coincide. It is thus achievable that the metering chamber for the purpose of transporting a liquid droplet to the outlet opening acts like a closed tube, wherein in addition a portion of the liquid of the plug during transport through the porous wall portion is removable and can be removed.

The metering method according to the invention is advantageously applicable to a metering method of the type described above, wherein a metered amount of a liquid is provided with a metering method according to the invention, in particular as described above and / or according to one of claims 11 to 16, and wherein the metered meter Amount of a measured variable, which is dependent on the number of particulate components in an emerging from the outlet opening of the metering liquid, is measured. For example, the measured quantity can be measured in at least one method or several methods from the group screening method, scattered light method, fluorescence method. The advantage here is that a volume-related number of particulate components in a liquid with relatively little expenditure on equipment is feasible.

This embodiment of independent inventive significance thus advantageously utilizes the fact that a defined volume of liquid leaves the metering chamber at the outlet. If one measures the number of particulate constituents, one has determined the concentration of the starting solution. This results in a volume-related number. Alternatively or additionally, however, a number of particulate constituents in the starting solution can be determined, for example if the porous wall region is impermeable to the particulate constituents. It can thus take place a concentration of the particulate components in the metering chamber. This is particularly advantageous if the measurement method for the starting solution, for example in one or the reservoir, would take a long time. The reduced volume with the invention after passing through the metering device then leads to a time savings in the measurement.

The invention will now be described in detail with reference to an embodiment, but is not limited to this embodiment. Further exemplary embodiments result from the combination of one or more features of the protection claims with one another and / or with one or more features of the exemplary embodiment.

It shows in a highly simplified representation for explaining the principle of the invention

1 shows a meter according to the invention with a metering device according to the invention in a first partial step of a metering method according to the invention,

FIG. 2 shows the counting device and metering device according to FIG. 1 in a second partial step of the metering method according to the invention and FIG

FIG. 3 shows the counting device and metering device according to FIG. 1 in a third partial step of the invention Dosing process.

FIG. 1 shows a counter designated as a whole by 1. The counter 1 has a metering device 2, which has an inlet opening 3 and an outlet opening 4.

Between the inlet opening 3 and the outlet opening 4, a metering chamber 5 is formed.

With a first means 6, a negative pressure can be applied to the outlet opening 4, through which a pressure difference between the inlet opening 3 and the outlet opening 4 is applied. As a result of this pressure difference, an inflowing liquid 7 can be conveyed at least partially through the metering chamber 5 to the outlet opening 4. This will be explained in more detail below.

The metering chamber 5 has a porous wall region 8 between the inlet opening 3 and the outlet opening 4.

On the outside, a removal opening 9 is formed and arranged on the porous wall region 8. The porous wall portion 8 thus defines a branch from the conveying path between the inlet opening 3 and the outlet opening 4 to the removal opening.

To the removal opening, a second means 10 is connected, with which a negative pressure at the removal opening 9 can be developed. This negative pressure causes a pressure difference between the discharge opening 9 and the inlet opening 3. This second pressure difference causes a portion 11 of the inflowing liquid 7 through the porous wall portion 8 of the Dosing chamber 5 is branched off. To the inlet opening 3, a reservoir 12 is connected on the outside.

The reservoir 12 is delimited or demarcated to accommodate any, but delimited liquid volume can.

The porous wall portion 8 has a plurality of pores 13. The pores 13 are formed with a diameter at which the capillary forces cause liquid received in the pores 13 to escape by itself. Here, the porous wall portion 8 is formed of a material which is wetted by the liquid to be metered, i. has a contact angle of less than 90 ° with this liquid.

If the liquid used is water or other polar liquid, the porous wall area is a hydrophobic membrane or a hydrophobic material.

In the case of non-polar liquids, the porous wall region 8 is formed of a hydrophobic membrane or of a hydrophobic material. About the pore size is in this case the strength of the capillary effect with which the liquid is retained in the pores 13, set or predetermined. The smaller the pores 13, the more pressure has to be expended to empty the pores 13.

The porous wall region 8 can be arranged interchangeably to the metering device 2 to different liquids and / or different second pressure differences customizable.

The porous wall region 8 extends over the entire length of the metering chamber 5 between the inlet opening 3 and the outlet opening 4. In further exemplary embodiments, the porous wall region 8 may have a shorter length than the metering chamber 5.

In the exemplary embodiment shown in FIGS. 1 to 3, the porous wall region 8 is formed on one side of the dosing chamber 5.

However, it can also be provided that the porous wall region 8 extends on all sides or on all sides of the dosing chamber 5. In this case, the porous wall region 8 thus extends over a circumference of the dosing chamber 5 which runs around a connecting line between the inlet opening 3 and the outlet opening 4. In the exemplary embodiment according to FIGS. 1 to 3 and also in further exemplary embodiments, on the outside of the porous wall region 8 a receiving space 14 is formed and arranged. The Au receiving space 14 serves to receive the branched portion 11 of the incoming liquid. 7

The receiving space 14 is filled with a not further apparent, superabsorbent polymer as a liquid-absorbent, air-permeable material. The negative pressure developed via the second means 10 can thus be supplied to the Entnahmöff 9 regardless of the filling amount in the receiving space 14, to set a constant second pressure difference.

The first means 6 and the second means 10 have a common same pump 15.

In further exemplary embodiments, the first means 6 and the second means 10 each have a pump at the point designated 15 in FIGS. 1 to 3. These can be formed completely separate from each other or integrated into a common housing. With these separately operable pumps can be applied to the channels 16 and 17 different negative pressures.

In further embodiments, it can be achieved and set up in another way that with the first means 6, a different negative pressure to the channel 16 can be applied and is applied as with the means 10 to the channel 17th

Corresponding, mutually differing pressure differences with respect to the inlet opening 3 result. The pump 15 in FIGS. 1 to 3 generates a negative pressure, which is supplied to the outlet opening 4 via an intake channel 16 of the first means 6.

The second means 10 has an intake passage 17, via which the vacuum developed by the pump 15 is supplied to the removal opening 9.

The respectively imparted negative pressures are equal, so that the first pressure difference is equal to the second pressure difference.

In the other embodiments already mentioned, the first pressure difference is set differently from the second pressure difference. With the metering device 2, a metering process for metering a liquid can be carried out, which will be described in more detail below with reference to FIGS. 1 to 3.

With the means 6, a first pressure difference between the inlet port 3 and the outlet port 4 is applied to promote an inflowing liquid 7 in the metering chamber 5. In this case, the inflowing liquid 7 is taken from a reservoir 12 connected to the inlet opening 3.

In a first partial step, which is shown in FIG. 1, the metering chamber is filled by the inflowing liquid 7 on the basis of the first pressure difference.

It can be seen in FIG. 1 that the fill level in the metering chamber 5 changes in such a way that an increasing proportion of the porous wall area 8 is covered with liquid from the metering chamber 5 or comes into contact.

The inflowing liquid 7 forms in the metering chamber 5 a front liquid meniscus 22, which moves in Figure 1 with advancing level in the metering chamber 5 to the right.

The negative pressure applied simultaneously via the second means 10 causes a pressure difference between the inlet opening 3 and the removal opening 9, through which a part 11 of the inflowing liquid 7 is withdrawn from the dosing chamber 5 through the porous wall area 8.

It can be seen that with progressive filling of the Dosing 5 an increasing area of the porous Wandbe ^¬ rich 8 is covered with liquid from the metering chamber 5 or comes into contact, so that an increasing part 11 of the inflowing liquid 7 is not discharged to the outlet port 4, but through the discharge opening 9.

At the same time, the hydrodynamic resistance according to Hagen-Poiseuille, which counteracts the flow in the metering chamber, also increases with increasing filling of the metering chamber.

The inflowing liquid 7 thus fills the metering chamber 5 until an equilibrium state shown in FIG. 2 is reached. For this purpose, the fluidic conductivity of the porous wall region 8 and the width, depth and length of the dosing chamber 5 are selected so that the equilibrium state is established. In addition, other parameters are set accordingly so that the equilibrium state is established at the desired position. These include the area of the porous wall portion 8 on the one hand and the difference in the pressure differences applied to the outlet opening 4 and the discharge opening 9 with respect to the inlet opening 3 when these pressure differences differ as described, on the other hand. In this equilibrium state, which is characterized by reaching a predetermined level 18, also equilibrium level, the inflowing liquid 7 passes completely through the porous wall portion 11 into the receiving space 14. The front liquid meniscus 22 characterized by the predetermined level 18, the liquid-air boundary, does not move forward in equilibrium.

This is the beginning of the second step of the dosing process. rens.

This equilibrium state, in which the level does not change, 18 stops until the reservoir 12 is completely emptied. In this case, the front liquid meniscus 22 remains in the dosing chamber 5 at the position shown in FIG.

The portion 11 of the inflowing liquid 7 branched off via the removal opening 9 is received in an absorbing material in the receiving space 14. This material, which is not shown to simplify the illustration in the figures, retains its air-permeable properties even after absorption of the liquid. Thus, the second pressure difference between the inlet opening 3 and the removal opening 9 remains constant and independent of the amount of liquid received in the receiving space 14.

In further embodiments, the receiving space 14 is formed without an absorbent material. The receiving space 14 is simply very large in these, for example, with a very small hydrodynamic resistance configured. Even so, it can be achieved that the second pressure difference remains approximately or exactly constant as the filling space of the receiving space 14 progresses.

As soon as the reservoir 12 is completely emptied, the third partial step of the metering process, which is shown schematically in FIG. 3, begins.

In this sub-step, the surface of the porous wall region 8 that is in contact with the liquid from the metering chamber 5 decreases. Thus, the area through the porous wall region 8 increases eligible amount of liquid again, so that the equilibrium is left as shown in FIG.

This means that the level of the liquid in the metering chamber 5 rises again. However, no liquid flows through the inlet opening 3, so that the quantity of liquid still present in the dosing chamber 5 forms a quantity of liquid 19 in the form of a plug, which is transported to the outlet opening 4.

In the third substep, a rear liquid meniscus 23 forms at the rear side of the liquid quantity 19 remaining in the dosing chamber 5 as a liquid-air boundary. The anterior fluid meniscus 22 resets itself in the third partial step.

At the same time, the rear liquid meniscus 23 also travels in the metering chamber 5, since no more liquid flows through the inlet opening 3.

During transport, a portion 20 of the amount of liquid 19 transported to the outlet opening 4 is further diverted through the porous wall portion 8. The quantity of liquid 19 therefore decreases during transport to the outlet opening 4 by a defined proportion.

During transportation, therefore, the rear liquid meniscus 23 and the front liquid meniscus 22 approach each other.

In the area behind the amount of liquid 19, ie between the remaining amount of liquid and the inlet opening 3, the porous wall portion 8 is no longer in contact with the liquid in the metering chamber 5.

In this case, in the portion of the porous wall region 8 which is no longer in contact with the liquid in the dosing chamber 5, the capillary forces in the pores 13 ensure that the porous wall region 8 remains impermeable to air. This prevents the second pressure difference between the inlet port 3 and the discharge port 9 from being short-circuited, which would lead to coincidence of the first pressure difference between the inlet port 3 and the discharge port 4.

As soon as the liquid quantity 19 has left the metering chamber 5, the metering process is ended and the remaining quantity of liquid 19 forms the metered quantity.

In the application according to the invention, this metered quantity can be supplied in a manner known per se in a counting method according to the invention of a merely indicated measuring device 21, which is set up, for example, to carry out a transmitted light method and / or a scattered light method and / or a fluorescence method.

With the measuring device 21, a measured variable can and will now be measured which depends on the number of particulate constituents in the liquid quantity 19 emerging from the outlet opening 4. From this measured variable, the required number can and will subsequently be calculated and related to the volume of the defined quantity of liquid quantity 19.

It should be mentioned that in the described dosing process at the same time a concentration of those components in the liquid or solution to be measured takes place, not can pass through the porous wall portion 8. This is for example useful to measure an absolute number of partiku ^¬ lar components in a large amount of liquid by the large amount of liquid is reduced by the method described before the count or number determination. Here, the porous wall portion 8 is impermeable to the particulate matter to be counted.

The metering device and the dosing method described are suitable for repeated executions. In this case, a plurality of liquid volumes which are supplied to the reservoir in succession and separately from one another can be reduced or measured in each case to the desired amount using the proposed metering method according to the invention.

In the metering method for providing a metered quantity of a liquid, it is proposed to form an inlet opening 3, an outlet opening 4 and a porous wall region 8 with an outside removal opening 9 on a metering chamber 5 and applying a first pressure difference between the inlet opening 3 and the outlet opening 4 to transport a liquid from a reservoir 12 connected to the outside of the inlet opening to the outlet opening 4 and at the same time to apply a second pressure difference between the outlet opening 9 and the inlet opening 3 to expel a portion of the liquid 7 flowing through the inlet opening via the porous wall area 8 branch off the metering chamber 5 until the reservoir 12 and the metering chamber 5 are emptied, wherein the metered amount of the liquid at the end of the process at the outlet opening 4 leaked and provided.

Claims

claims

Metering device (2), having a metering chamber (5) having an inlet opening (3) and an outlet opening (4), wherein a first means (6) for applying a first pressure difference between the inlet opening (3) and the outlet opening (4) is formed for conveying a metered quantity of a liquid (7) flowing through the inlet opening (4) through the metering chamber (5) to the outlet opening (4), characterized in that the metering chamber (5) has a porous wall area (8), in that the porous wall region (8) forms on the outside a removal opening (9) and in that a second means (10) for applying a second pressure difference between the removal opening (9) and the inlet opening (3) is formed around a part (11) of FIG the inlet (3) inflowing liquid (7) through the discharge opening (9) branch off.

Dosing device (2) according to claim 1, characterized in that the inlet opening (3) is connected to a closed or lockable reservoir (12).

Dosing device (2) according to claim 1 or 2, characterized in that the removal opening (9) through the porous wall portion (8) is separated from the metering chamber (5) and / or that the porous wall portion (8) is formed by a membrane.

Dosing device (2) according to one of claims 1 to 3, characterized in that the porous wall region (8) over a length of the metering chamber (5) between the input Laßöffnung (3) and the outlet opening (4) extends and / or that the porous wall portion (8) extends over a connecting line between the inlet opening (3) and the outlet opening (4) circumferential circumference of the metering chamber (5).

Dosing device (2) according to one of claims 1 to 4, characterized in that on the outside of the porous wall portion (8) a receiving space (14) is formed and / or that the receiving space (14) with a liquid keitsabsorbierenden, air-permeable material, especially a superabsorbent polymer.

Dosing device (2) according to one of claims 1 to 5, characterized in that a pore size and a choice of material are matched to the second pressure difference, that the second pressure difference is less than a capillary pressure in the porous wall region (8).

Dosing device (2) according to one of claims 1 to 6, characterized in that the first means (6) comprises a first pump (15) which is connected to the outlet opening (4), and / or that the second means (10) a second pump (15) which is connected to the removal opening (9).

Dosing device (2) according to one of claims 1 to 7, characterized in that the first pump (15) and the second pump (15) are identical and / or that the first pressure difference is equal to the second pressure difference.

Dosing device (2) according to one of claims 1 to 8, characterized in that a length of the porous wall Area (8) along a connecting line between the inlet opening (3) and the outlet opening (4) is tuned to the first pressure difference and the second pressure difference that at a predetermined level (18) of the metering chamber (5) a balance between one per unit time is adjusted by the inlet opening (3) entering amount of liquid and in the time unit through the discharge opening (9) branched liquid amount until a outside of the inlet port (3) connected reservoir (12) is emptied, and / or that the first pressure difference on the second pressure difference is adjusted so that, when the reservoir (12) is empty, an amount of liquid (19) located in the metering chamber (5) can be transported at least partially to the outlet opening (4).

Counting device (1) for determining a volume-related or absolute number of particulate constituents in a liquid, characterized in that a metering device (2) according to one of claims 1 to 9 is present and in that the outlet opening (4) of the metering device (2) Measuring device (21) is connected, wherein the measuring device (21) for measuring a measured variable, which is dependent on the number of particulate components in a from the outlet opening (4) of the metering device (2) leaking liquid amount (19) is arranged.

Dosing method for metering a liquid, wherein a first pressure difference between an inlet opening (3) and an outlet opening (4) of a metering chamber (5) is applied to a metered amount of a through the inlet opening (3) inflowing liquid (7) through the Dosing chamber (5) to promote the outlet opening (4), characterized in that the metering chamber (5) has a porous wall portion (8) with an externally formed on the porous wall portion (8) removal opening (9) and that during the Conveying the liquid from the inlet opening (3) to the outlet opening (4), a second pressure difference is applied between the inlet opening (3) and the removal opening (9), around a part (11) of the liquid (7) flowing through the inlet opening (3) ) via the removal opening (9) from the metering chamber (5) preferably continuously divert.

Dosing method according to claim 11, characterized in that the inflowing liquid (7) is conveyed from a reservoir (12) connected to the inlet opening into the dosing chamber (5) and / or that the process is ended when the reservoir (12) and / or the dosing chamber (5) is empty / are.

Metering method according to claim 11 or 12, characterized in that in a first sub-step the metering chamber (5) through the inlet opening (3) is filled to a predetermined level (18) and / or that in a second sub-step, in particular if the metering chamber ( 5) to which a predetermined fill level (18) is filled with liquid, a per unit of time through the inlet opening (3) entering liquid amount is completely removed or sucked through the removal opening (9) until a to the inlet port (3) connected to the reservoir (12) is emptied.

14. dosing method according to one of claims 11 to 13, characterized in that in a third sub-step, in particular after the reservoir or a reservoir (12) connected to the inlet opening (3) has been emptied, a quantity of liquid (1) located in the metering chamber (5) is partially diverted through the removal opening (9) and partially into the metering chamber (5) to the outlet opening ( 4), wherein a total amount of liquid transported to the outlet opening (4) is provided as a metered quantity of the liquid.

5. Metering method according to one of claims 11 to 14, characterized in that the through the porous wall portion (8) branched off part (11) of the liquid outside the removal opening (9) by an absorbent, air-permeable material, in particular a superabsorbent polymer, is added ,

6. dosing method according to one of claims 11 to 15, characterized in that the second pressure difference is set equal to the first pressure difference and / or that the second pressure difference is set smaller than a capillary pressure in the porous wall region (8).

7. Counting method for determining a volume or absolute number of particulate components in a liquid, characterized in that a metered amount of a liquid is provided with a metering method according to any one of claims 11 to 16 and in that the metered amount of a measured variable of the Number of particulate constituents in the dosed amount depends on is measured.