EP2222959B1 - Method for supplying a fluid and micropump for said purpose - Google Patents

Abstract

A device includes a number of N≧2 pump chambers having N separate chamber volumes, each of which may be altered independently of the other(s). The volume changes of the pump chambers occur periodically with substantially the same frequency (f). The device further includes N actuators for changing the respective chamber volumes and valves for establishing the pumping direction, and finally a common inlet and outlet. The pump chambers of the device are disposed in series one behind the other, and the forms of the periods of volume changes of all pump chambers are substantially identical. Moreover, an ideal phase offset PHI of approximately 180° exists between the volume change of the chamber volumes of two sequential pump chambers.

Description

The invention relates to the field of pumped delivery, and more particularly to methods of pumping small and minute quantities of fluid, and more particularly to pumps constructed of pumping chambers, diaphragm actuators and valves.

State of the art and disadvantages

Pumps for conveying fluids, ie gases and liquids and mixtures thereof have long been known and available in a wide variety.

Also, the still young discipline of microsystems technology compared to other branches of industry requires corresponding funding. Some of the pumping techniques known from the general state of the art have been transferred to the field of microsystem technology with varying degrees of success in recent years. A frequently underestimated problem here is the provision of a bladder-tolerant device, since, due to the small dimensions of the pumping chambers used in micropumps, even the smallest bubbles lead to obstruction of the channels and / or the pumping chambers. Gas bubbles can, for example, occur during the first use of the pump, by bubbles already present in the pumping medium, by the formation of gas bubbles from a gas initially dissolved in the liquid, or by a strong negative pressure.

Silicon-based pumps are known from the prior art, in which essential parts such as pumping diaphragm and / or valves made of silicon are produced by means of etching techniques, as for example from the document US 2004/0001767 A1 , from which emerge the features of the preamble of claim 1. Another such construction is found, inter alia, in HTG van Lintel, FCM van de Pol, "A piezoelectric micropumps based on micromachining of silicon", Sensors and Actuators, 15 1988, pp. 153-167 , Such pumps are generally sensitive to gas bubbles in the fluid stream and are therefore often lined with hydrophilic coatings, with the high hydrophilicity of the silicon base material being advantageous. However, the possibilities of avoiding problems by gas bubbles entrained in the fluid flow are limited, in particular in the case of single-chamber pumps.

As drive mostly piezoceramic and thermally, electrostatically or electromagnetically acting actuators are used.

Furthermore, peristaltic pumps are described, which have the ability due to their multi-chamber structure to press gas bubbles, which are located in a first chamber, by emptying them in the next chamber, without any risk of retraction of the gas bubble. Such a structure is for example the publication WO 95/20105 removable. The juxtaposition of several individual pumps creates a pump cascade. By a phase offset, which is for example in three chambers 120 °, a continuous transport of the fluid is achieved in one direction.

Although such peristaltic pumps on the one hand robust against gas bubbles in the fluid react, they always need at least three chambers, otherwise the phase offset would be 180 °, so that the conveying direction would not be defined. Furthermore, the drive of the three or more chambers requires a corresponding amount of space and energy for operation.

Object of the invention and solution

The object of the invention is therefore to provide a device and a method for conveying fluids, which is miniaturizable, energy-saving and bubble-tolerant and also allows effective promotion.

Accordingly, an apparatus according to claim 1 and a method according to claim 6 are proposed. Further embodiments are set forth in the dependent claims and the following description and the accompanying drawings.

description

In particular, the invention relates to a device and a method for the bubble-tolerant and effective delivery of a fluid, which are particularly suitable for use in microsystems technology due to their simple and robust construction, such as in the field of life sciences, medical technology, personal hygiene, cosmetics Also, the above invention is well suited for use in environmental technology, toys, or other particularly harsh environments.

• eine Anzahl von mindestens zwei Pumpkammern, von denen jede ein eigenes Kammervolumen aufweist, und von denen jedes Kammervolumen unabhängig von allen anderen veränderbar ist. Dabei verlaufen die Volumenänderungen der Pumpkammern im Wesentlichen jeweils periodisch mit einer im Wesentlichen gleichen Frequenz f;
• N Aktuatoren zur Veränderung der jeweiligen Kammervolumina, wobei N der Anzahl der Pumpkammern entspricht und jeder Aktuator einer bestimmten Pumpkammer zugeordnet werden kann;
• eines oder mehrere Ventile zur Festlegung der Pumprichtung;
• einen gemeinsamen Einlass und einen gemeinsamen Auslass, von denen jeder unabhängig vom anderen und bevorzugt so ausgestaltet ist, dass er elastische Schläuche, oder nach alternativen Ausführungsformen auch als Schraubgewinde, als Lueranschluss, als Bohrung oder als Steckanschluss ausgeführt sein kann;
• sowie nach einer bevorzugten Ausführungsform ein gemeinsames Gehäuse, in welches die beschriebenen Komponenten integrierbar sind.

Accordingly, the invention comprises in particular the following basic components:

• a number of at least two pumping chambers, each having its own chamber volume, and each chamber volume being variable independently of all the others. In this case, the volume changes of the pumping chambers essentially each run periodically at a substantially identical frequency f;
• N actuators for changing the respective chamber volumes, wherein N corresponds to the number of pumping chambers and each actuator can be assigned to a specific pumping chamber;
• one or more valves for determining the pumping direction;
• a common inlet and a common outlet, each of which is independent of the other and Preferably, it is designed so that it can be designed elastic hoses, or according to alternative embodiments as a screw thread, as a Luer connection, as a bore or as a plug connection;
• and according to a preferred embodiment, a common housing into which the described components can be integrated.

In the device according to the invention, the N pumping chambers are arranged serially one behind the other, and the forms of the periods of volume changes of all the pumping chambers are substantially identical, and there is an ideal phase offset PHI of approximately 180 ° between the volume change of the chamber volume of two successive pumping chambers.

Depending on the nature of the actuators, their control takes place, for example, electrically, mechanically, magnetically, and preferably the drive curve of the actuator predetermines the change in volume in the respective pumping chamber. An ideal phase offset is to be distinguished from an actual phase offset PHI *; By this it is meant that in certain circumstances, as will be shown, a deliberate deviation from the ideal value can be sought, but that in the basic configuration from each pumping chamber to the next, a phase shift PHI of 180 ° is to be set. Thus, in the case of four pumping chambers, the first and third would be in phase, and the second and fourth would be just opposite the first and third chambers.

According to a preferred embodiment of the device according to the invention, this is characterized in that N = 2, so it consists of just two pumping chambers. This is the smallest of the possible chamber numbers; As experiments have shown, the device is able, provided that it has a structure according to the teaching set forth herein and is used according to the inventive method to be described, to meet all the requirements arising from the problem set out above, in particular the requirement an excellent bladder tolerance.

To a sufficiently safe, i. in particular also bubble-tolerant and efficient operation, the actual phase offset PHI * should preferably deviate not more than ± 7% and more preferably not more than ± 3% from the ideal phase offset PHI. Depending on the pumping medium, density, temperature, flow rate and structure of the pumping device, these numbers may vary; In general, a smaller deviation is always preferable. Preferably also the N. and the N + 2. Actuator are each addressed with the same control curve, so that at least all even or all odd pumping chambers work in exactly the same phase.

The device according to the invention is intended for use with fluids. In this case, the fluid may be a liquid, a gas, or a liquid-gas mixture, in which the gas may be dissolved in the liquid and / or in the form of bubbles. Such liquids can for example, be blood or other body fluids in which dissolved gas is present, which shows under certain pressure changes in the form of (mostly undesirable) gas bubbles, which in turn can block the pumping device. By using the device according to the invention, such gas bubbles can no longer lead to a blockage of the pumping device, which is of particular importance in the field of medical technology.

According to a preferred embodiment of the device according to the invention, each pumping chamber preferably comprises at least one separate inlet and / or at least one outlet valve, and particularly preferably two separate inlet valves and two separate inlet valves. Exhaust valves. Experiments have shown that with the use of double valves, a particularly high degree of reliability in the operation of the device can be achieved.

According to a particularly preferred embodiment, the valves are arranged and configured such that the directional changes in the fluid flow caused by them are minimized. This minimizes the energy required to transport the fluid and further reduces the likelihood of gas bubbles settling. The exact configuration of the fluid components depends on the type of actuators used, pumping chamber shapes, etc.; As a rule, however, it can be said that angle changes in the fluid path should not be abrupt and in particular right angles should be avoided. Change from one fluid level to another Sufficiently slow and shallow, meaning that the bore connecting both fluid planes should have a diameter at least as long as their length.

According to a preferred embodiment of the device according to the invention this is characterized in that it comprises the change of the respective chamber volumes Piezomembranaktuatoren. In particular disk or plate-shaped actuators are particularly preferred. However, other actuators for changing the respective chamber volumes are conceivable, such as mechanical, thermal, magnetic, electrostatic or other, a change in the chamber volume inducing actuators, in particular those are particularly preferred, which have a particularly low energy and space requirements.

According to another preferred embodiment, all components in contact with the fluid are made of polyphenylsulfone (PPSU). This material offers desirable advantages, in particular with regard to the joining and manufacturing methods preferred for joining the invention. Of course, the invention is in no way limited to this material. Thus, for example, it may be necessary to specially coat the fluid-related parts in the medical or environmental field, for example by biocompatible or other, especially inert, materials to adapt the device to the specific requirements. Also other materials, like Silicon, metals or glasses are conceivable, it being necessary to ensure in the case of materials which are less extensible that the actuators can still lead to a change in the chamber volume according to the invention.

According to a further embodiment of the device, all the components to be connected to one another can be connected by means of the "laser transmission welding" method. This method is particularly suitable for joining plastics and, in addition to short production times, offers the possibility of producing, without adhesives, a hermetically sealed connection which approximates the strength of the original material. Especially in the field of medical technology, this method is used successfully. Depending on the wavelength of the laser used for welding, it must be ensured that one absorbing and one transparent component are to be connected to each other.

According to a further embodiment, the device comprises geometric configurations such that a faulty assembly of the components is largely excluded. This is particularly advantageous if the assembly of the device is done manually, and as a result of possibly similar components of the individual pumping chambers, or due to almost symmetrical configurations of these components there is a risk of confusion. Since the correction of such incorrect assembly costs time and at worst results in defective pumps, such mounting errors are to be avoided in any case. This can according to the invention be done by the fact that certain marks or projections are on the housing, which allow the mounting of other components only in a very specific way, so that incorrect installation is practically impossible, since they attract attention immediately or are possible only with damage of the component. Such mounting aids are therefore preferably made of one or more raised parts and with these corresponding recesses on other components. Particular preference is given to those embodiments which extend in a direction perpendicular to the individual layers or functional planes through the entire housing, so that only a minimal number of such embodiments is necessary.

According to a particularly preferred embodiment, the device is characterized in that the necessary for the production of a single pumping chamber components, in particular the or the valves and the actuator, compared to the components required for the production of another pumping chamber of the same device substantially interchangeable or identical with these is designed or are. In other words, if possible, all actuators, all valves and possibly other components that are repeated in each pumping chamber are in each case configured identically. In this way, on the one hand, the likelihood of confusion during assembly is reduced, on the other hand, the costs are minimized in the production, since a correspondingly larger number of identical components can normally be produced more cost-effectively than several different variants with correspondingly smaller numbers.

• ein Bodenelement mit einer Ausnehmung, sowie einem in die Ausnehmung hinein führenden Einlass und einem aus der Ausnehmung heraus führenden Auslass, sowie außerdem zwischen dem Ein- und dem Auslass in derselben Ebene befindlichen Fluidstrukturen zur Führung des zu fördernden Fluids zu den Ventilen und zur fluidischen Konnektierung beider Pumpkammern und zur Anbindung an den Einlass und den Auslass;
• eine Ventilfolie, die in die Ausnehmung einlegbar ist und die beweglichen Teile der Ventile trägt;
• eine Zwischenschicht, die oberhalb der Ventilfolie in die Ausnehmung einlegbar ist und Öffnungen aufweist, welche die nicht beweglichen Teile der Ventile bilden
• eine Schutzschicht, die oberhalb der Zwischenschicht in die Ausnehmung einlegbar ist und die mit der Zwischenschicht zwei in einer Ebene liegende Hohlräume bildet, die als Pumpkammern dienen;
• zwei Aktuatoren mit Elektroden und elektrischen Anschlüssen, wobei jeder Aktuator jeweils kongruent mit der darunter liegenden Pumpkammer angeordnet ist, und wobei durch Betrieb des Aktuators das Kammervolumen der ihm zugeordneten Pumpkammer veränderbar ist;
• ein Deckelelement, dessen Außenkonturen im Wesentlichen denen des Bodenelements entsprechen, und das auf das Bodenelement auflegbar ist und das nach Verbinden mit dem Bodenelement die Ausnehmung dergestalt abschließt, dass die in ihrem Inneren befindlichen Bauelemente vor äußeren Einflüssen geschützt sind.

According to a most preferred embodiment of the device according to the invention, this comprises the following components, wherein the enumeration order substantially corresponds to the assembly order:

• a bottom element with a recess, and an inlet leading into the recess and an outlet leading out of the recess, and also between the inlet and the outlet in the same plane fluid structures for guiding the fluid to be conveyed to the valves and for fluidic Konnektierung both pumping chambers and for connection to the inlet and the outlet;
• a valve sheet which is insertable into the recess and carries the movable parts of the valves;
• an intermediate layer which can be inserted into the recess above the valve film and has openings which form the non-moving parts of the valves
• a protective layer which can be inserted into the recess above the intermediate layer and which, with the intermediate layer, forms two in-plane cavities which serve as pumping chambers;
• two actuators with electrodes and electrical connections, wherein each actuator is arranged in each case congruent with the underlying pumping chamber, and wherein by operation of the actuator, the chamber volume of the associated pumping chamber is variable;
• a cover element, the outer contours of which substantially correspond to those of the floor element, and which can be placed on the floor element and which, after being connected to the floor element, terminates the recess in such a way that the components located in its interior are protected from external influences.

In this case, the bottom element, the intermediate layer and the cover element can be connected to one another in a fluid-tight manner.

It is clear that this enumeration can be supplemented by further, meaningful or necessary further components for the corresponding application and therefore should not be regarded as conclusive.

According to another embodiment, the device is not constructed as described above as an integrated variant, but by juxtaposing separate individual pumps. It thus consists of a serial arrangement of N separate, each comprising only a single pumping chamber individual pumps, which are designed to be connected to each other by means of fluidic lines. Such lines are preferably made of a material as unyielding material to avoid the loss of energy by (unwanted) widening of the lines in each pumping cycle. Therefore, such lines are particularly preferably as short as possible, for example not more than 10 centimeters, to design.

However, the control of the individual pumps is of course again according to the pattern described above, according to which there is a phase offset PHI of 180 ° between each successive pumping chambers.

• Mindestens einer der Aktuatoren ist abschaltbar ausgebildet. Hierzu kann bevorzugt eine Schaltungsanordnung vorgesehen sein, die nicht nur den frequenzgesteuerten Betrieb des Aktuators ermöglicht, sondern auch über eine Ansteuermöglichkeit verfügt, die ein vorübergehendes oder auch dauerhaftes Aussetzen mindestens eines oder auch mehrerer Aktuatoren im laufenden Betrieb erlaubt. Dabei kann das Aussetzsignal beispielsweise vom ersten Aktuator in Durchflussrichtung "wandern", so dass immer nur einer, aber nicht immer derselbe Aktuator vorübergehend stillsteht.
• Eine Schaltungsanordnung ist vorgesehen, die es gestattet, die durch mittels Fluiddruck an dem mindestens einen abgeschalteten Aktuator erzeugte Formänderung des Aktuators während des Betriebes der Vorrichtung mit einem oder mehreren nicht abgeschalteten Aktuator(en) zu detektieren. Mit anderen Worten erlaubt die Schaltungsanordnung ein Auslesen der durch den "passiven" Betrieb, also ohne Antriebsenergie erfolgenden, hervorgerufenen Formänderungen des mindestens einen abgeschalteten Aktuators. Im beispielhaften Falle von Piezoaktuatoren wird durch eine von Außen aufgebrachte Formänderung, z.B. durch Druckänderung in der Pumpkammer, eine Spannung induziert, welche dann über geeignete elektrische Leitungen nach Außen geleitet und dort gemessen werden kann. Als Leitungen können besonders bevorzugt auch die ohnehin bereits vorhandenen Leitungen verwendet werden, die zum Betrieb des jeweiligen Aktuators nötig sind. Besonders bevorzugt ist die für die erfindungsgemäße Auslesbarkeit der Formänderungen vorgesehene Schaltung in die Schaltung zur Ansteuerung rund zum temporären Abschalten des bzw. der Aktuatoren integriert und gewünschtenfalls mit einer Schnittstelle zu einem Bedienfeld, einem Computer oder einem Funkübertrager ausgestattet.

According to another preferred embodiment, the. Device designed so that information about the state of conveyance can be obtained during operation. For this purpose, the device comprises the following features:

• At least one of the actuators is designed to be switched off. For this purpose, a circuit arrangement may preferably be provided, which not only allows the frequency-controlled operation of the actuator, but also has a control possibility, which allows a temporary or permanent exposure of at least one or more actuators during operation. In this case, the exposure signal can, for example, "migrate" in the direction of flow from the first actuator, so that only one, but not always, the same actuator is temporarily stopped.
• A circuit arrangement is provided, which makes it possible to detect the shape change of the actuator produced by means of fluid pressure at the at least one deactivated actuator during operation of the device with one or more non-deactivated actuators. In other words, the circuit arrangement allows a read-out of the "passive" operation, ie without drive energy, caused changes in shape of the at least one deactivated actuator. In the exemplary case of piezo actuators, a voltage is induced by an externally applied change in shape, for example by a change in pressure in the pumping chamber, which voltage can then be conducted to the outside via suitable electrical leads and measured there. As lines, the already existing lines which are necessary for the operation of the respective actuator can be used with particular preference. Particularly preferably, the circuit provided for the readability of the shape changes according to the invention is integrated into the circuit for triggering around the temporary shutdown of the actuator (s) and optionally equipped with an interface to a control panel, a computer or a radio transmitter.

In the following, in particular, the method according to the invention will be described in more detail, which is particularly preferably carried out together with the device according to the invention.

• aus einer Anzahl von N ≥ 2 Pumpkammern mit N separaten Kammervolumen besteht, von denen jedes unabhängig von dem bzw. den anderen veränderbar ist, wobei die Volumenänderungen der Pumpkammern im Wesentlichen jeweils periodisch mit einer im Wesentlichen gleichen Frequenz f verlaufen;
• N Aktuatoren zur Veränderung der jeweiligen Kammervolumina umfasst;
• außerdem ein oder mehrere Ventile zur Festlegung der Pumprichtung bereitstellt;
• und schließlich einen gemeinsamen Einlass und Auslass umfasst.

Accordingly, the method is suitable for the bubble-tolerant and efficient delivery of a fluid, wherein it advantageously cooperates with a device which:

• consists of a number of N ≥ 2 pumping chambers with N separate chamber volumes, each of which is independently variable from the other, wherein the volume changes of the pumping chambers substantially each periodically run at a substantially same frequency f;
• N comprises actuators for changing the respective chamber volumes;
• also provides one or more valves for defining the pumping direction;
• and finally comprising a common inlet and outlet.

The N pumping chambers are arranged serially one behind the other. The inventive method requires that the forms of the periods of volume changes of all pumping chambers are substantially identical, and that the pumping chambers are controlled such that there is an ideal phase offset PHI of approximately 180 ° between the volume change of the chamber volume of two successive pumping chambers.

According to a preferred embodiment, the inventive method cooperates with a device for which N = 2, which therefore consists of two pumping chambers. The phase offset between the first and the second pumping chamber is 180 ° in accordance with the method according to the invention.

According to a preferred embodiment, an actual phase offset PHI * does not deviate more than ± 7% and in a particularly preferred embodiment not more than ± 3% from the ideal phase offset PHI. As a general rule The rule is that smaller deviations from the ideal value are always to be preferred.

The process according to the invention is particularly preferably suitable for conveying fluids which are selected from the group of liquids, gases and liquid / gas mixtures, the process being in the case of a mixture both present and in the form of bubbles dissolved in the liquid Gas shares is suitable.

Preferably, the change in the volume of each pumping chamber takes place in accordance with a rectangular curve. In the case of electrically driven actuators, e.g. Piezoaktuatoren, this means that their control is ideally done with mutually phase-shifted square voltages .. By the control by square-wave voltage, the actuator moves accordingly, resulting in the optimal case of an approximately rectangular cyclic volume change of the respective pumping chamber. In the event that the allocation between actuation of the actuator and volume change of the pumping chamber is not proportional, appropriate correction factors or functions can be used.

According to a preferred embodiment of the method according to the invention, the rising and / or falling edge of the square-wave voltage / curve is rounded in such a way that cavitation effects in the pumping chamber caused by insufficient chamber pressure are avoided. Experiments have shown that if the actuator relaxes too quickly, a negative pressure can develop in the pumping chamber, which leads to spontaneous gas bubble formation, since the boiling point in a fluid depends on its pressure state and also drops sharply at lower pressures, in extreme cases up to room temperature. The subsequent collapse of the cavitation gas bubbles during normalization of the pressure results in strong pressure waves, which can lead to significant material damage in the event of permanent occurrence and should therefore be avoided.

According to a further embodiment of the method according to the invention, the frequencies f of the volume changes of successive pumping chambers may have a difference A temporarily or continuously. This difference is as desired _; specifically set difference in the frequency of the individual chambers. If, for example, the difference is just 1 Hz at an operating frequency of 100 Hz, then the differing chamber again reaches the same phase offset after 100 cycles as at the beginning of the induced frequency change. As could be shown by experiments, this temporary introduction of a so-called "beating" is particularly well suited for discharging gas bubbles which otherwise can not be released from the fluidic channels of the device. Depending on the specific configuration of the device as well as the physical properties of the fluid, the difference .DELTA. May be of different sizes and different lengths in order to obtain an optimum result.

According to a particularly preferred embodiment of the method, the difference Δ is preferably less than 1% of the frequency f and particularly preferably less than 0.1% of the frequency f.

1. (1) vorübergehendes oder kontinuierliches Abschalten eines öder mehrerer Aktuatoren. Dies ist insbesondere dann sinnvoll, wenn entweder der Aktuator selber die Möglichkeit bietet, auch als Sensor für Druckänderungen in der jeweiligen Pumpkammer zu dienen, oder wenn ein dazu geeigneter Drucksensor anderweitig vorhanden ist.
2. (2) Detektieren der durch die mittels Fluiddruck an dem bzw. den Aktuator(en) erzeugten Formänderung(en). Dies ist besonders bevorzugt mittels Piezoaktuatoren möglich, welche im "passiven" Betrieb, also ohne Aufbringen einer elektrischen Spannung, ihrerseits eine Spannung erzeugen, sobald sie einer Formänderung unterliegen. Unter bestimmten Voraussetzungen sind der Druck, die durch ihn verursachte Formänderung und die dadurch hervorgerufene Spannung auch proportional zueinander, so dass ein Piezoaktuator als ein einfacher Drucksensor umfunktionierbar ist.
3. (3) Vergleich der detektierten Formänderungen mit Sollwerten, die aus einem ordnungsgemäßen Betrieb stammen. Sind nämlich Werte, beispielsweise Spannungswerte, aus einem Betrieb ohne Störung bekannt, so kann durch einfachen, qualitativen Vergleich auf das Vorliegen einer Störung, oder durch quantitativen Vergleich in erster Näherung auch auf die Größe der Störung rückgeschlossen werden.

According to a preferred embodiment of the method according to the invention can also be obtained with this information about the delivery state during operation. This requires at least one of the following steps to be taken; most preferably, all of the following steps must be performed sequentially:

1. (1) Temporary or continuous shutdown of one or more actuators. This is particularly useful if either the actuator itself offers the opportunity to serve as a sensor for pressure changes in the respective pumping chamber, or if a suitable pressure sensor is otherwise available.
2. (2) Detecting the shape change (s) produced by the fluid pressure on the actuator (s). This is particularly preferably possible by means of piezoactuators, which in turn generate a voltage in "passive" operation, ie without application of an electrical voltage, as soon as they undergo a change in shape. Under certain conditions, the pressure, the change in shape caused by it and the voltage caused thereby also proportional to each other, so that a piezoelectric actuator as a simple pressure sensor is umunktionierbar.
3. (3) Comparison of the detected shape changes with set values resulting from proper operation. If values, for example voltage values, are known from an operation without disturbance, the magnitude of the disturbance can be deduced by a simple, qualitative comparison on the existence of a disturbance, or by quantitative comparison in a first approximation.

Depending on the embodiment, the fault detection can only be temporarily assumed by one or more actuators, or one or more actuators can be permanently converted as fault sensors. Similarly, the reading of one or more separately introduced and unspecified here sensors can temporarily serve to detect malfunctions. Advantageously, however, the embodiment according to which the already existing actuators are temporarily used as fault sensors.

According to a particularly preferred embodiment of the method according to the invention, upon detection of a disturbance to remedy the same temporarily a change in operation as described above is triggered, ie, there is generated a beat according to the invention, with which the disturbance can be corrected again, provided that they occur an otherwise non-removable gas bubble was caused.

LIST OF FIGURES

Fig. 1:

Exploded view of the device according to the invention

Fig. 2:

optimized curve for control or volume change

3:

Curve course at 180 ° offset phases; Duty cycle = 1: 1

4:

Curve course at 180 ° offset phases; Duty cycle ≠ 1: 1

figure description

FIG. 1 shows an exploded view of a particularly preferred embodiment of the device according to the invention 1. This consists of a layer-like structure 1, which comprises two pumping chambers 2 in the illustrated case.

• ein Bodenelement 7, welches besonders bevorzugt aus Kunststoff hergestellt wird. Das Bodenelement umfasst eine Ausnehmung 7', in welche alle folgenden Bauelemente ein- oder aufgelegt werden. Das Bodenelement beinhaltet bevorzugt auch den zum Fördern des Fluids nötigen Einlass 4 und Auslass 5, der, wie hier gezeigt, beispielsweise jeweils als rohrartiger Anschluss ausgebildet ist. Selbstverständlich sind auch andere, der jeweiligen Applikation angepasste Anschlusstypen denkbar. Ebenso umfasst das Bodenelement Teile der für die Ventile 3 notwendigen Fluidkanäle, die bevorzugt im Spritzgussverfahren und somit im selben Arbeitsgang wie das Bodenelement selber hergestellt werden.

Corresponding FIG. 1 the structure 1 consists in detail of the following components:

• a bottom element 7, which is particularly preferably made of plastic. The bottom element comprises a recess 7 ', in which all the following components on or be placed. The bottom element preferably also includes the inlet 4 and outlet 5 necessary for conveying the fluid, which, as shown here, for example each formed as a tubular connection. Of course, other, adapted to the particular application connector types are conceivable. Likewise, the bottom element comprises parts of the necessary for the valves 3 fluid channels, which are preferably produced by injection molding and thus in the same operation as the bottom element itself.

• Eine Ventilfolie 8, welche die beweglichen Teile der Ventile 3 trägt und in das Bodenelement eingelegt wird. In der dargestellten Form umfasst die Ventilfolie die beweglichen Teile sowohl der Einlassventile 3' einer jeden Pumpkammer, als auch die beweglichen Teile der entsprechenden Auslaßventile 3". Weiterhin umfasst die Ventilfolie auch die Aussparungen der Montagehilfe 7"', welche einem fehlerfreien Einbau der Ventilfolie dienen.
• Eine Zwischenschicht 9, die bevorzugt aus einem Kunststoff gefertigt ist. Diese ist so ausgestaltet, dass sie sich in die Ausnehmung 7' des Bodenelementes 7 einfügen lässt. Im Zentrum einer jeden Pumpkammer 2, welche jeweils durch eine Vertiefung in der Zwischenschicht entsteht, befindet sich jeweils eine Öffnung 9', durch welche Fluid in die Pumpkammer ein- bzw. wieder aus dieser herausströmen kann.
• Eine Schutzschicht 10, welche auf die Zwischenschicht aufgebracht wird und somit die Pumpkammer fluidisch nach oben hin abschließt. Die Schutzschicht muss demnach fest mit der Zwischenschicht verbunden werden, so dass weder an ihrem Umfang noch im Bereich zwischen den Pumpkammern Fluid aus- bzw. überströmen kann. Hierzu wird, wie bereits erwähnt, vorzugsweise das Laserdurchstrahlschweißen angewendet. Alternative Fertigungsverfahren sind das Kleben, das Ultraschallschweißen, oder das mechanische Klemmen der jeweiligen Bauelemente.
• zwei Aktuatoren 6, welche in der dargestellten Ausführungsform als scheibenförmige Piezoaktuatoren ausgeführt sind. Jeder der Aktuatoren ist geometrisch auf die darunter liegende Pumpkammer 2 angepasst und trägt zur elektrischen Kontaktierung entsprechende Elektroden 6'. Mit diesen verbunden ist ein elektrischer Anschluss 6", welcher aus dem Gehäuse der Vorrichtung 1 heraus geführt werden kann, und der eine ausreichende Anzahl von Einzeladern zur Konnektierung eines jeden Aktuators bereithält.
• ein Deckelelement 11, welches den Abschluss des im Wesentlichen aus dem Bodenelement 7 bestehenden Gehäuses der Vorrichtung 1 dient. Bevorzugt ist auch das Deckelelement aus Kunststoff hergestellt und mit dem Bodenelement mittels Laserdurchstrahlschweißen verbindbar ausgestaltet.

In addition, the bottom element carries as an assembly aid raised parts of the same 7 "in the form of geometric features, which are arranged so that they cooperate with the recesses of the mounting aid 7"'. Thus, the installation of the following components such as a valve sheet 8 can be done only in one way, so that incorrect assembly is largely excluded.

• A valve sheet 8, which carries the movable parts of the valves 3 and is inserted into the bottom element. In the illustrated form, the valve film comprises the moving parts of both the inlet valves 3 'of each pumping chamber and the moving parts of the respective outlet valves 3 " ,
• An intermediate layer 9, which is preferably made of a plastic. This is designed so that it can be inserted into the recess 7 'of the bottom element 7. In the center of each pumping chamber 2, which arises in each case by a depression in the intermediate layer, there is one each Opening 9 ', through which fluid in the pumping chamber on or can flow out of this again.
• A protective layer 10 which is applied to the intermediate layer and thus closes the pumping chamber fluidically upwards. Accordingly, the protective layer must be firmly connected to the intermediate layer so that fluid can not flow out or over either at its circumference or in the area between the pumping chambers. For this purpose, as already mentioned, preferably laser transmission welding is used. Alternative manufacturing methods are gluing, ultrasonic welding, or mechanical clamping of the respective components.
• two actuators 6, which are designed in the illustrated embodiment as a disk-shaped piezo actuators. Each of the actuators is geometrically adapted to the underlying pump chamber 2 and carries for electrical contacting corresponding electrodes 6 '. Connected to these is an electrical connection 6 ", which can be guided out of the housing of the device 1, and which holds a sufficient number of individual cores for the connection of each actuator.
• a cover element 11 which serves to close the housing 1 of the device 1, which essentially consists of the bottom element 7. Preferably, the cover element is made of plastic and configured connectable to the bottom element by means of laser transmission welding.

FIG. 2 shows a diagram in which the time on the abscissa, on the ordinate the actuator voltage U (hereinafter called "driving curve") and / or the volume of a pumping chamber (hereinafter referred to as "chamber volume curve") is or are plotted. The illustrated amount of time corresponds to just one period, ie the time necessary for a single pumping cycle of a pumping chamber.

The dashed line shows an ideal rectangle curve. According to the invention, both the rising flank A and the falling flank B of this curve can be rounded, so that a curve corresponding to the solid line results, which represents the optimized curve. As described above, this rounding serves to avoid pressure change peaks, which can lead to unwanted cavitation bubble formation. The exact optimized shapes of the fillets must be determined according to the exact geometric design of the pumping chambers, the fluid channels and the magnitude of the operating pressures. This can be done for example by calculation, simulation and / or the execution of test series. The form shown here is therefore to be understood only as a symbol and does not correspond to the actual, optimal form of the control or chamber volume curve.

FIG. 3 shows a diagram with the same axis captions as before FIG. 2 , Likewise, it shows the solid line FIG. 2 , which the optimized curve sales of the drive or

Chamber volume curve reflects. In addition, as a dotted line, a PHI = 180 ° out of phase curve is plotted showing the drive curve of the actuator following that which is driven according to the solid line. In the variant shown here, the lifting and lowering phases of an actuator, the so-called duty cycle, are approximately the same length, which is why the almost mirrored shape of the dotted line results (duty cycle 1: 1). In cases where the duty cycle is not the same, there are images in which the wake of the second drive curve does not correspond accordingly as a reflection of the first.

Diester case is in FIG. 4 shown. Here, the phase response PHI is again 180 °, but the duty cycle is approximately 1: 3 (the time period at which the curve shows a high value is significantly shorter than the part at which it is close to zero).

Method of conveying a fluid and micropump therefor

LIST OF REFERENCE NUMBERS

1

Device for conveying a fluid

2

pumping chamber

3

Valve

3 '

intake valve

3 '

Exhaust valve "

4

inlet

5

outlet

6

Actuator, piezomembrane actuator

6 '

electrode

6 "

electrical connection

7

floor element

7 '

recess

7 "

raised part of the mounting aid

7 " '

Recesses of the mounting aid

8th

valve film

9

interlayer

9 '

openings

10

protective layer

11

cover element

A

rising bare

B

falling edge

Claims (8)

1. A device for supplying a fluid in a bubble-tolerant manner, wherein said pump device has at least two pump chambers (2) each of which comprises a separate chamber volume, in each case a diaphragm for periodically changing the volume of the pump chamber, and in each case a separate actuator for actuating the diaphragm, and further comprises valves for the flow direction and inlet and outlet, wherein the pump chambers are arranged in series one behind the other and wherein the forms of the volume change of the pump chambers have a phase offset of approximately 180°, characterized by

   - a bottom element (7) with a recess (7') and inlet (4) running into the recess (7') and an outlet (5) running out of the recess (7'), and, moreover, fluid structures located in the same plane between the inlet and the outlet for guiding the fluid to be supplied to the valves (3, 3', 3") and for fluidically connecting both pump chambers (2) and for connecting to the inlet (4) and the outlet (5);

   - a valve film (8) which can be placed into the recess (7') and carries the movable parts of the valves (3, 3', 3") ;

   - an intermediate layer (9) which can be placed above the valve film (8) into the recess (7) and which has openings (9') which form the non-movable parts of the valves (3, 3', 3");

   - a protective layer (10) which can be placed above the intermediate layer (9) into the recess (7') and which, together with the intermediate layer (9), forms two hollow spaces which lie in one plane and serve as pump chambers (2);

   - two actuators (6) with electrodes (6') and electrical connections (6"), wherein each actuator (6) is in each case arranged congruent with the pump chamber (2) therebelow, and wherein by operating the actuator (6), the chamber volume of the pump chamber (2) arranged in each case below the actuator (6) can be changed;

   - a cover element (11), the outer contours of which correspond substantially to the ones of the bottom element (7) and which can be placed onto the bottom element (7) and which, after connecting to the bottom element (7), closes the recess (7') in such a manner that the components located inside said recess are protected against external influences;

   and wherein bottom element (7), intermediate layer (9) and cover element (11) can be connected to each other in a fluid-tight manner.
2. The device according to claim 1, characterized in that said device is formed by a serial arrangement of N separate individual pumps which in each comprise only one pump chamber (2) and which are configured to be connectable to each other by means of fluid lines.
3. The device according to claim or claim 2, wherein:

   the device is configured such that information about the supply state can be obtained during running operation and wherein for this purpose, the device comprises the following features:

   - at least one of the actuators (6) is configured such that it can be switched off;

   - a circuit arrangement is provided which allows to detect the form changes of the actuator (6) generated by means of fluid pressure during the operation of the device at an actuator (6) that is switched off with an actuator (6) that is not switched off.
4. The device according to any one of the claims 1 to 3, characterized in that an actual phase offset PHI* preferably does not deviate more than ±7 % and particularly preferred not more than ±3 from the ideal phase offset PHI.
5. The device according to claim 1, characterized in that the activation of the actuators (6) is configured substantially such that it can be carried out with square-wave voltages which are phase-shifted with respect to each other and wherein:

   the rising and/or the falling edge of the square-wave voltage/curve is rounded such that cavitation effects in the pump chamber (2) caused by chamber pressure that is too low can be avoided.
6. A method for pumping a fluid in a bubble-tolerant manner with a device according to any one of the claims 1 to 5, characterized in that temporarily or continuously, the frequencies f of the volume changes of sequential pump chambers (2) have a difference Δ, wherein
   the difference Δ is preferably selected to be smaller than 1% of the frequency f and particularly preferred smaller than 0.1% of the frequency f.
7. The method according to claim 6, characterized in that information about the supply state during the running operation is obtained in such a manner that at least one of the following steps and preferred all steps is or are, respectively, carried out in succession:

   - temporarily or continuously switching off one or a plurality of actuators (6);

   - detecting the form changes generated by means of fluid pressure at the actuator or the actuators (6);

   - comparing the detected form changes with set values originated from a proper operation.
8. The method according to claim 6 or claim 7, characterized in that upon detection of a failure and for eliminating the same, a change of the operation according to claim 6 is initiated temporarily.

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