DE102016014832A1 - Chamber pump and method for operating a chamber pump - Google Patents

Abstract

The invention is a chamber pump (10) and a method of operation thereof, the chamber pump (10) having a pump chamber (12), a chamber diaphragm (14) or a piston (34) and a volume for changing the volume of the pump chamber (12 ) on the chamber membrane (14) or the piston (34) engaging and axially movable drive rod (24), characterized in that it acts as an actuator for influencing an axial position of the drive rod (24) and on the one hand on the drive rod (24 ) and on the other hand on a housing of the pump (10) attacking electroactive membrane (40, 40 ') and that during operation of the chamber pump (10), the electroactive diaphragm (40, 40') for influencing an axial position of the drive rod (24) and to receive a return stroke or a Vorhubs the chamber pump (10) is acted upon by an electric potential.

Description

The invention relates to a gas or liquid chamber pump hereinafter referred to briefly as a pump. As a chamber pump while a piston or diaphragm pump is referred to, in which in a conventional manner during operation due to movement of a piston or a membrane at least partially by means of the piston or the diaphragm limited volume of a pump chamber changes periodically and due the periodic volume change of the pump chamber results in a delivery of a respective medium and / or a pressure change upstream or downstream of the pump. The invention relates to such a chamber pump intended for use in a medical device or in a safety-related system.

In a medical device such a pump is used, for example, to drive respiratory gas in order to transport sample gas - in particular a patient gas - from a sampling location to a measurement location or to control or drive other actuators. With respect to use of such a pump in connection with an analysis of a patient's gas, reference may be made to aspirating patient gas monitoring in anesthesia and a so-called remote system in mobile personal gas sensing. In a safety-related system, such a pump is used, for example, for a mobile or stationary analysis of noxious gases in the air. Also, by means of the pump, for example, a transport of sample gas from a sampling point to a measuring location. In addition, such pumps in a medical device or in a safety-related system also come to the generation of auxiliary pressures into consideration. In principle, the invention proposed here also comes into consideration for applications beyond medical devices and safety-related systems, for example for measuring and analysis devices. This is below always read without special notice.

Pumps of the type mentioned are available in various embodiments, for example with a crank mechanism or a linear drive. Furthermore, pumps are known in which the drive is realized piezoelectrically. The respective drive acts on a diaphragm or a piston in a respective pump head. In both types (diaphragm or piston), the volume in the pump chamber (compression space) in the pump head is periodically changed by means of the drive. This leads to a volume transport and to a pressure generation. The relationship between the volume transport and the pressure results from the geometry of the pump chamber, the stroke volume, the operating frequency, the switching behavior of the required valves and the external pneumatic load.

Pumps for gases and liquids currently available on the market in a power range from 0 mbar to 110 mbar or 200 ml / min to 1100 ml / min or 0 mbar to 300 mbar at 200 ml / min can be operated at their operating point by changing the stroke frequency a drive by means of an electric motor by changing the speed - be adjusted. A further adjustment must be made by an external pneumatic circuit in the respective application. In special cases different pump heads have to be mounted.

A change in the stroke frequency affects the pulsation frequency and the alternating component in the pressure curve. This has the following drawbacks: Firstly, traditional measures to suppress the pulsation, such as a low pass, lose their effect. On the other hand, avoidance of certain sensor-critical frequencies can not be ensured. Finally, the coordination of a pneumatic system with the pump is more difficult.

Particularly high stroke frequencies (> 100 Hz) mean extreme loads on the components of the pump. The losses caused by no longer inertly responsive valves increase enormously. The phase of the closing angle of the valves shortens or lengthens and shifts in relation to the stroke movement of the piston or the membrane. The proportion of flexing work in the seal (piston) or the membrane increases drastically. Finally, a significantly increased noise development of the respective pump is associated with a high stroke frequency.

At low stroke frequencies (<10 Hz) a continuous pressure curve is no longer guaranteed. Each pump stroke can be recognized as a stronger pressure pulse and also as a flow pulse. Attenuation or buffering by a buffer volume requires a very large buffer volume. A large volume distorts the gas fronts with changing gas mixtures. In a drive by means of an electric motor, this is at low stroke frequencies in a critical work area. Discontinuous angular velocities with high brush wear in the collector (brush motors) are only a negative aspect. In addition, the speed is often too low for the construction of a lubricating film in the camps. Furthermore, those coils that are in use shortly before the peak load at the dead center of the pump, more heavily loaded, so there is temperature peaks in these coils. Finally, the moment of inertia of the rotor is insufficient to ensure a buffering of the load torque.

Although linear pumps which can be used as an alternative to electric motor-driven pumps are easy to control, they are significantly more inefficient due to their larger air gaps and require a higher power. In addition, their operation is associated with a higher temperature development. Such linear pumps are also significantly more expensive and expensive to manufacture and maintain, because for the control of the linear motion an additional and above all fast sensors for detecting the position and / or speed of the drive is needed. In addition, necessary for a low-vibration run compensation of linearly moving masses complicated structures.

Piezo-electrically driven pumps are energetically suitable only for miniature applications.

Based on the findings of the prior art outlined above, it is an object of the present invention to provide a well adjustable linearly driven chamber pump and a method of operating the same, which avoids or minimizes at least some of the disadvantages outlined above.

This object is achieved by means of a chamber pump (pump) with the features of claim 1 and with regard to a method for operating such a pump by means of a method having the features of the parallel independent method claim. It is in a chamber pump of the type mentioned, a pump chamber, a chamber membrane or a piston as a means for cyclically changing the volume of the pump chamber during pumping operation and for cyclically changing the volume of the pump chamber to the chamber membrane or the piston attacking and axially movable drive rod comprises, at least one intended for influencing an axial position of the drive rod and on the one hand on the drive rod and on the other hand on a housing of the pump attacking electroactive membrane provided. The or each electroactive membrane acts as an actuator with respect to the axial movement of the drive rod and at least in part replaces a previous drive of the chamber pump.

In a corresponding method for operating such a chamber pump or a chamber pump with one or more further features described below at least one on the one hand to the drive rod and on the other hand on a housing of the pump or the like attacking electroactive diaphragm for influencing an axial position of the drive rod and to obtain a Return stroke or a Vorhubs the chamber pump, namely a return stroke or a Vorhubs the chamber membrane or the piston, acted upon by an electrical potential.

A chamber pump is a cyclically operating machine for the conveyance of liquids or gases. These are referred to collectively as the medium below. As is known, a pump cycle includes a return stroke and a forward stroke (or a forward stroke and a return stroke) and this continues in subsequent pump cycles. The mentioned at least one electroactive membrane is intended either to maintain or assist a return stroke or a pre-stroke. Below, a special embodiment of the chamber pump proposed here will be explained, in which in each case at least one electroactive membrane for obtaining or supporting a return stroke (return stroke) and a Vorhubs is determined (Vorhubmembran). As long as it does not matter whether the at least one diaphragm is intended to maintain or support a return stroke or a pre-stroke, a partial lift is discussed, with a complete pump cycle comprising a first partial lift and a second partial lift, for example the return stroke and the advance stroke , Accordingly, the method for operating a chamber pump of the kind outlined so far characterized by the fact that at least one on the one hand on the drive rod and on the other hand on a housing of the pump or the like attacking electroactive diaphragm for influencing an axial position of the drive rod and to obtain a partial stroke of the chamber pump, namely a Teilhubs the chamber membrane or the piston, is acted upon by an electrical potential.

The application of the at least one membrane with an electrical potential causes, in a generally known manner, a change in the so-called aspect ratio (ratio of thickness to area) of the electroactive membrane. Briefly, by applying an electrical potential, an effective length of the at least one diaphragm between its fixed points increases on the one hand on the drive rod and on the other hand on a housing of the pump or the like. When the electrical potential disappears, the original aspect ratio is restored and, accordingly, the effective length of the at least one membrane is reduced. The electroactive membrane is preferably biased. This leads to defined conditions. Without an applied electrical potential results in an effective length corresponding to the bias voltage. When an electrical potential is applied, the effective length of the electroactive membrane is determined by the respective potential (the effective length increases with the applied electric potential).

A periodic change in the effective length of the at least one electroactive membrane resulting from an alternating application of the at least one electroactive membrane can be used frictionless, noise-free and wear-free to drive a chamber pump, namely to drive a chamber membrane comprising it or one of them piston. In addition, advantageously very high stroke frequencies are possible.

Another advantage of the invention is that such an electroactive membrane can be produced very inexpensively and processed and applied automatically. Furthermore, such an electroactive membrane has a very low mass in relation to conventional drives. This applies both to the proportion of moving masses as well as to the mass as a whole. The moving mass is an important reason why conventional linear drives can not be used for many applications, especially for applications with high stroke frequencies. In contrast to the rotating masses of a motor, which can often be easily balanced, moves in a so-called oscillating armature drive, the mass of the armature in a linear direction and thus shifts the center of gravity periodically. This leads to vibrations and noise, which are not given in a drive of the type proposed here.

The following description is continued in terms of a linguistic simplification and in the interest of better readability of an optional embodiment, in which instead of at least one electroactive membrane, which acts on the one hand to the drive rod and on the other hand, for example, on the housing of the pump, exactly one electroactive membrane with these fixed points is provided. Such a single electroactive membrane in the form of a conical film / membrane attacks, for example, in its center on the drive rod and is fixed at its sides, for example, on the pump housing, in particular jammed or glued. As regards engagement with the drive rod, such a single electroactive diaphragm has, for example, at its center a hole through which the drive rod or a portion of the drive rod of smaller diameter is guided, the edges of the hole being fixed to the drive rod, for example Jamming, gluing or the like. As an alternative to such an embodiment, an embodiment is contemplated in which instead of a single electroactive membrane, multiple membranes are used, each fixed to the drive rod, extending radially outwardly from the drive rod and fixed to the pump housing at the opposite end, for example. The direction of the force action is determined by the location of the attack on the drive rod and the location of the attack, for example on the pump housing. Therefore, exactly one membrane and a plurality of individual membranes have the same effect, provided that the same place of attack on the drive rod and a same place of attack, for example, on the pump housing are given. This is assumed here. Accordingly, whenever the exact electroactive membrane is mentioned, the alternative embodiment will always be read with a plurality of membranes acting in the same direction as the single electroactive membrane.

Advantageous embodiments of the invention are the subject of the dependent claims. This used backlinks point to the further development of the subject matter of the main claim by the features of the respective subclaim and are not to be understood as a waiver of the achievement of an independent, objective protection for the feature combinations of the related subclaims. Furthermore, in view of an interpretation of the claims and the description in a closer specification of a feature in a subordinate claim, it should be assumed that such a restriction in the respective preceding claims and a more general embodiment of the subject pump or the method for their operation does not exist is. Each reference in the description to aspects of subordinate claims is therefore to be read even without special reference expressly as a description of optional features. Finally, it should be noted that the chamber pump may also be developed according to the dependent method claims, for example in that the chamber pump comprises means for carrying out the corresponding method step or the corresponding method steps, and vice versa, so that with respect to the disclosure of individual device and method aspects of the invention is always mutually referenced or can be.

In one embodiment of the chamber pump, this includes a return element. By means of acting as an actuator electroactive membrane, a force for the deflection of the drive rod in a first direction can be applied and is applied during operation of the chamber pump. By means of the return element is a force for deflecting the drive rod in a direction opposite to the first direction second direction applied and is applied during operation of the chamber pump. One of the two Teilhube (return stroke or Vorhub) of a complete pump cycle can be triggered by means of the electroactive membrane and is triggered during operation of the chamber pump by means of the electroactive membrane (movement of the drive rod in the first direction). The complementary Teilhub (forward stroke or return stroke) can be triggered by means of the return element and is the Operation of the chamber pump triggered by the return element (movement of the drive rod in the first direction opposite the second direction). As a restoring element, for example, a spring (compression spring or tension spring) comes into consideration, whose direction of force is oriented opposite to a resultant force due to the electroactive membrane force direction. A cyclic loading of the electroactive membrane with an electrical potential leads to a first partial stroke and the complementary second partial stroke is triggered by means of the return element. The resulting alternating release of the first and second Teilhube leads to a pumping action. For this purpose, the pump comprises, for example, a control unit with at least one input via which the partial lift can be triggered on the basis of the electroactive membrane, for example by supplying the control unit and thus the pump at the respective input with the electrical potential applied to the electroactive membrane shall be.

In a particular embodiment of the chamber pump acts as a restoring element exactly one or at least one further (second) electroactive membrane. The simplification introduced above also applies here, so that in the following, too, in the interest of better readability - but without renouncing any further general validity - a second electroactive membrane is used. This also acts on the one hand on the drive rod and on the other hand, for example on a housing of the pump, in particular in a form as has been explained above for the first mentioned electroactive membrane. In a chamber pump with a (exactly one or at least one) acting as the first actor electroactive membrane and a (exactly one or at least) second acting as an actuator electroactive membrane these attack on the one hand on the drive rod and on the other hand on the housing of the chamber pump or the like and are intended to exert a force on the drive rod in each case in the axial direction of the drive rod. The exerted by the second electroactive membrane on the drive rod and exerted in operation force is directed antiparallel to the exercisable by means of the first electroactive membrane on the drive rod and exerted in operation force. In such a chamber pump and in a method for operating such a chamber pump one of the two Teilhube (return stroke or Vorhub) of a complete pump cycle by means of the first electroactive membrane can be triggered and is triggered during operation of the chamber pump by means of the first electroactive membrane (movement of the drive rod in the first direction). The complementary partial stroke (forward stroke or return stroke) can be triggered by means of the second electroactive membrane and is triggered during operation of the chamber pump by means of the second electroactive membrane (movement of the drive rod in the second direction opposite the first direction). The second electroactive membrane acts as a return element for the partial stroke triggered by means of the first electroactive membrane. Equally, however, the first electroactive membrane also acts as a restoring element for the partial stroke triggered by means of the second electroactive membrane. An alternating or at least phase-shifted loading of the first electroactive membrane and of the second electroactive membrane with an electrical potential leads to an alternating triggering of the first and second sub-hubs and thus to a pumping action. For this purpose, the pump comprises, for example, a control unit with inputs via which the first and the second partial lift can be triggered, for example by supplying the electrical unit with which the first or second pump is connected to the control unit and thus to the pump at the respective input electroactive membrane to be acted upon.

Alternatively, an embodiment of a control unit into consideration, in which the control unit of the pump, for example, a connection for an electrical potential and at least one input, wherein the pump by means of the input, a desired value for a desired pump position is specified, for example in the form of Setpoint that encodes a measure of a desired axial position of the drive rod. The control unit of the pump then automatically determines, based on the desired value, an electrical potential which is to be applied to the electroactive membrane (or to which the first or the second electroactive membrane is to be acted upon or to which the first and the second electroactive membrane are to be acted upon) to obtain a desired or at least substantially corresponding pump position corresponding to the desired value. The respectively determined electrical potential is automatically generated by the pump control from the externally applied electrical potential. This is done, for example, by means of a controllable with a pulse width modulated signal electronic switch, for example, a transistor which is connected in a circuit with the electroactive membrane (or the electroactive membranes) that, when the switch is closed, the externally applied potential applied to the electroactive membrane , As a function of time, due to the pulse-width-modulated signal used to drive the switch, a potential is produced across the electroactive membrane (or the respective electroactive membrane), which leads to the desired deflection of the drive rod. The fundamental frequency of the pulse width modulated signal is chosen to be sufficiently high, for example not below 1 kHz, so that it is ensured that individual pulses of the pulse width modulated signal cause no change in the aspect of the electroactive membrane.

By means of such a control unit or the like, the first electroactive membrane is acted upon in accordance with a predetermined or predetermined first voltage profile with an electrical potential and applied to the second electroactive membrane according to a predetermined or predetermined second voltage profile with an electrical potential in a particular embodiment of the method. By specifying the first and / or second voltage profile, for example, the duration of the first partial lift and / or second partial stroke and thus the total stroke frequency, the amplitude of the first partial lift and / or second partial stroke and thus the total displacement and / or the temporal change the volume of the pump chamber can be specified. In this way, the essential parameters of a pumping operation can be set individually or in combination.

In a specific embodiment of the chamber pump, the first electroactive membrane engages in front of the second electroactive membrane on the drive rod, namely, starting from the attacking on the chamber membrane or on the piston end of the drive rod in front of the second electroactive membrane. By considering the points of application of the two electroactive membranes starting from said end of the drive rod, a direction is defined. Along this direction, in this particular embodiment, the first electroactive diaphragm acts against the drive rod on the pump housing or the like before its point of application, and the second electroactive diaphragm engages the drive rod on the pump housing or the like in the same direction behind its point of application. This allows a compact design of the chamber pump.

In a further and particularly preferred embodiment of a chamber pump of the type described here and in the following, the electroactive membrane - or in one embodiment with a first and a second electroactive membrane one of the two membranes or both membranes - acts as a sensor for obtaining positional information regarding a position the chamber membrane or the piston. Just as an electroactive membrane changes its aspect ratio and in particular its thickness when an electrical potential is applied, the change in thickness also changes the measurable electrical capacitance between two electrodes placed on the surface of the electroactive membrane. Such a signal is proportional to a respective thickness of the membrane and thus also proportional to a respective effective length of the membrane. The effective length of the membrane is in turn proportional to the axial position of the movable means of the membrane drive rod, so that the measured capacitance is a measure of the position of the drive rod and thus a measure of the position of the chamber membrane or the piston. Accordingly, a signal obtainable by means of a capacitance measurement provides position information regarding the position of the chamber membrane or the piston, generally referred to as the pump position. On the one hand, such position information can be used as the actual value for a position of the pump and made available, for example, to a higher-level system. This thus has always up-to-date information regarding the pump position and this can be displayed, for example. However, the position information can also be compared with an expected pump position and output the result of the comparison as state information or possibly an error message can be generated. The pump position may additionally or alternatively also be used for a control or regulation of the pump. The control or regulation is then implemented, for example, in a control unit of the pump or a control unit of a higher-level system. In such a control unit, the latter continuously compares a respective desired value for the position of the pump with the position information (actual value) representing the current position of the pump and generates a manipulated variable in a generally known manner as a function of a possible deviation between setpoint and actual value to extinguish the control deviation or at least to minimize the control deviation, namely a manipulated variable, by means of which the applied to the electroactive membrane (or an electroactive membrane or both electroactive membranes) electrical potential is adjusted.

In a particular embodiment of a chamber pump which on the one hand comprises both a first electroactive membrane for a first partial stroke and a second electroactive membrane for a second partial stroke and on the other hand a measurement value which encodes positional information is obtainable by means of a measurement on an electroactive membrane, it is provided that that the first electroactive membrane and the second electroactive membrane act alternately as an actuator and as a sensor. Then cyclically alternating the first and the second electroactive Impacted membrane with an electric potential to obtain the first and second partial stroke. If, for example, the first electroactive membrane is subjected to an electrical potential and this leads to a change (increase) in its effective length, this also affects the aspect ratio of the second electroactive membrane, in particular in the case of prestressed membranes. This change is measurable as described above and, for example, a capacitance measurement provides position information. The same applies accordingly if the second electroactive membrane is subjected to an electrical potential and accordingly the position information is determined by means of a measurement, in particular a capacitance measurement, with respect to the first electroactive membrane. The alternating use of one of the two membranes either as a sensor or as an actuator prevents a falsification of the measurement for determining the position information due to an applied electrical potential and accordingly ensures particularly reliable measured values with regard to the position information.

The method and embodiments of the method and the method steps included therein are carried out automatically, ie without intervention by the user, for example a user of a medical device comprising the pump or the like. The automatic execution of the method steps takes place under the control of a control unit. This includes, for example, a processing unit in the form of or in the manner of a microprocessor and a memory. A control program executable by the processing unit is loaded or loadable into the memory, which is executed during operation by its processing unit. In that regard, the invention is also a pump with a control unit, wherein the control unit comprises an implementation of the method described here and below (for example in software), operates according to the method and as a means for performing the method at least one control unit with an implementation of Includes method. The implementation of the method is preferably carried out in software. On the one hand, the invention is thus also a computer program with program code instructions executable by a computer (the control unit or its processing unit) and, on the other hand, a storage medium with such a computer program, ie a computer program product with program code means, and finally also a control unit, in its memory as a means for execution the method and its embodiments, such a computer program is loaded or loadable.

An embodiment of the invention will be explained in more detail with reference to the drawing. Corresponding objects or elements are provided in all figures with the same reference numerals.

The or each embodiment is not to be understood as limiting the invention. Rather, in the context of the present disclosure, modifications and modifications are possible, in particular those variants and combinations, for example, by combination or modification of individual in combination with the described in the general or specific description part and in the claims and / or the drawings features for the Professional with regard to the solution of the task are removable and lead by combinable features to a new object.

• 1 eine Kammerpumpe mit einem Kurbeltrieb,
• 2 eine Kammerpumpe mit einem Schwingankerantrieb und einer Feder als Rückstellelement,
• 3 elektroaktive Folien und das Ergebnis eines daran angelegten elektrischen Potentials
• 4 eine Ausführungsform einer hier vorgeschlagenen Kammerpumpe am Ende eines Rückhubs (links) und am Ende eines Vorhubs (rechts),
• 5 eine spezielle Ausführungsform einer hier vorgeschlagenen Kammerpumpe,
• 6 und 7 Spannungsprofile zur Beaufschlagung einer elektroaktiven Membran zur Auslösung eines Rückhubs und eines Vorhubs,
• 8 und 9 unterschiedliche Volumina der Pumpenkammer der Kammerpumpe als Ergebnis verschiedener elektrischer Potentiale sowie
• 10 eine weitere spezielle Ausführungsform einer hier vorgeschlagenen Pumpenkammer, bei der elektroaktive Folien entweder als Aktor für eines Auslösung eines Rückhubs oder eines Vorhubs fungieren oder als Sensor zur Ermittlung einer Positionsinformation der Pumpe fungieren.

Show it:

• 1 a chamber pump with a crank mechanism,
• 2 a chamber pump with a rocking armature drive and a spring as a restoring element,
• 3 electroactive films and the result of an applied electrical potential
• 4 An embodiment of a chamber pump proposed here at the end of a return stroke (left) and at the end of a forward stroke (right),
• 5 a special embodiment of a chamber pump proposed here,
• 6 and 7 Voltage profiles for applying an electroactive membrane to trigger a return stroke and a forward stroke,
• 8th and 9 different volumes of the pump chamber of the chamber pump as a result of different electrical potentials as well
• 10 a further specific embodiment of a pump chamber proposed here, in which act electroactive films either act as an actuator for triggering a return stroke or a Vorhubs or act as a sensor for determining a position information of the pump.

The illustrations in 1 and 2 show in a schematically simplified manner two basically known per se embodiments of a below sometimes briefly as a pump 10 designated chamber pump 10 , Every pump 10 has a pump chamber 12 on the one hand by an elastic membrane 14 and on the other hand by a housing part 16 a pump housing having at least one inflow and outflow opening formed therein is limited. The below for distinction as a chamber membrane 14 designated membrane 14 is laterally with the housing part 16 connected. The or each inflow opening and the or each outflow opening is in each case a valve 18 . 20 associated with, which releases or closes the inflow or outflow opening synchronously with the pump cycle.

The pump cycle results during operation of the pump 10 due to a respective drive of the pump 10 , As drive is in 1 a rotating drive (crank drive) shown, whose rotary motion by means of a disc with an eccentrically arranged crank pin (eccentric disc 22 ) or the like in a generally known manner in an oscillating, linear movement of a on the chamber membrane 14 attacking drive rod (connecting rod) 24 is implemented. In 2 is an electromagnetic drive (coil 26 with an at least partially ferromagnetic drive rod 24 ), pointing directly at the drive rod 24 acts and together with a restoring force exerting spring element 28 also to an oscillating, linear movement of the chamber membrane 14 attacking drive rod 24 leads. A pump 10 This type is called Schwingankerpumpe and the at least partially ferromagnetic part of the drive rod 24 correspondingly referred to as anchor 30. The drive rod 24 is each in a leadership 32 guided.

Due to the axially oscillating movement of the drive rod 24 becomes the chamber membrane 14 cyclically tense or relaxed. During the return stroke of the drive rod 24 becomes the chamber membrane 14 strained and there is an increase in the volume of the chamber 12 , During the forward stroke of the drive rod 24 becomes the chamber membrane 24 relaxed and there is a reduction in the volume of the chamber 12 , This applies to one by means of the drive rod 24 driven piston 34 ( 9 ) corresponding. As the chamber volume increases, a respective medium flows into the chamber via the or each inflow port 12 , When subsequently reducing the chamber volume is at least a part of the previously in the chamber 12 inflowing medium through the or each outflow opening from the chamber 12 repressed. The result is a volume flow of the pumped medium and / or a pressure reduction upstream of the pump in a manner known per se 10 and / or a pressure increase downstream of the pump 10 ,

The representation in 3 shows in schematically simplified manner an electroactive membrane 40 (electroactive foil 40 ). It may be a hereinafter sometimes briefly as a membrane 40 designated electroactive membrane 40 in the form of an electroactive polymer (EAP) or a dielectric elastomer (DEA) act. Both variants are hereafter with every mention of the membrane 40 or a membrane 40 always read along.

Electroactive polymers and dielectric elastomers are basically known per se. A membrane formed from this 40 - or generally an electroactive membrane 40 As is known, its aspect ratio (ratio of thickness to area) varies depending on an applied electrical potential. Additionally or alternatively, such a membrane 40 adjustable in terms of their elasticity, so that depending on the applied potential, a stiff and not or little bendable membrane or an elastic, bendable membrane results, as for example in the US 2004 124384 A1 is described.

In the upper part of the illustration in 3 is a membrane 40 shown, which is not subjected to an electrical potential. Immediately below is the same membrane 40 shown when subjected to an electrical potential. Visible is due to the application of an electrical potential, the thickness of the membrane 40 reduced. Here, the area of the membrane has 40 elevated. The latter is in the representation only in the form of an enlargement of the expansion of the membrane 40 along one of their main axes, ie in the form of a change in length, recognizable.

The application of a membrane 40 with an electric potential is in the illustration in 3 in the form of two on the membrane 40 attacking lines 42, 44 shown. The wires 42 . 44 lead to an electrical energy source, not shown, so that by means of the lines 42 . 44 an electrical potential to the respective membrane 40 can be created. For a membrane 40 , which is not subjected to an electrical potential, these lines 42 . 44 Not shown. In fact, these are wires 42 . 44 in a specific embodiment of the innovation described below, of course, regardless of whether to the respective membrane 40 an electrical potential is applied or not. The application of a membrane 40 with an electrical potential is, for example, by means of one in a circuit with the lines 42 . 44 existing switching element, for example, an electronic switch in the form of a transistor or the like, controlled in a basically known manner. For the interpretation of the figures applies that visible lines 42 . 44 an applied with an electric potential membrane 40 whereas a membrane 40 without such visible wires 42 . 44 in the particular snapshot shown is not acted upon by an electrical potential.

In the lower part of the illustration in 3 are two membranes 40 shown, which together form a membrane pair. In the relaxed, that is potential-free state, these are arranged in a same plane next to each other and adjacent to each other. In the area where the two membranes 40 adjacent to each other, a spring element is placed. At one to the membranes 40 applied potential also changes the modulus of elasticity of the two membranes 40 and the membranes which have become flexible due to the applied electrical potential 40 be partially through the Spring element raised, as shown in the snapshot shown.

Based on the lower illustration in 3 I would like to point out another peculiarity in the interpretation of the following figures. For paired membranes 40 , so a membrane pair as in the lower illustration in 3 , or several related membranes 40 The following applies: Even if in the interest of clarity of presentation only for a membrane 40 to these connected lines 42 . 44 are shown (and thus an exposure to an electrical potential is shown), this applies - so the exposure to the electrical potential - for the other membrane 40 of the membrane pair or any other associated membrane 40. Related membranes 40 are therefore always applied simultaneously either with an electrical potential or not subjected to an electrical potential.

Based on the above with reference to 3 Illustrated shows the representation in 4 now a first embodiment of a pump 10 of the type proposed here, with respect to known components of the pump 10 to the description 1 is referenced.

The representation in 4 shows the drive rod on the left side 24 at the lower vertex and on the right side at the upper vertex of the oscillating motion. Accordingly, on the left side is a situation with a maximum volume of the chamber 12 shown. As the chamber volume increases, the respective medium flows into the chamber up to the illustrated position of the chamber membrane 14 12 , On the right side, on the other hand, is a situation with a minimum volume of the chamber 12 shown. With a reduction in the chamber volume is up to the illustrated position of the chamber membrane 14 the respective medium from the chamber 12 repressed.

The movement of the chamber membrane 14 or alternatively the movement of a piston 34 ( 9 ) - arises due to the oscillating motion of the one in a leadership 32 led drive rod 24 , The movement of the drive rod 24 However, this results in contrast to the representations in 1 and 2 ) no longer due to a crank mechanism or a linear drive of in 1 shown type. The drive of the drive rod 24 rather, by means of at least one electroactive membrane 40 or a plurality of symmetrically about the drive rod in the radial direction 24 distributed electroactive membranes 40 and a return element acting in the opposite direction.

The or each membrane 40 engages on the one hand on the outer surface of the drive rod 24 and on the other to a housing of the pump 10 at. At one to the or each membrane 40 applied electrical potential ( 4 : Representation on the left side) increases the effective length of the or each membrane 40 between their attachment on the one hand, for example, on the pump housing and on the other hand on the drive rod 24 , An acting on the drive rod 24 return element 28 , for example, a spring element 28 - In particular a spring element 28 in the form of acting as a tension spring spiral spring -, then directs the drive rod 24 according to the increased effective length of the or each membrane 40 out, leaving a return stroke of the drive rod 24 and correspondingly a return stroke of the chamber membrane 14 results. This leads to the above-described increase in the chamber volume. Once the or each membrane 40 is no longer subjected to an electrical potential ( 4 : Representation on the right side) results again the original - shorter - effective length of the or each membrane 40 , The drive rod 24 is by means of the or each membrane 40 against the force of the return element 28 moved in the direction of a forward stroke. This results in a forward stroke of the chamber membrane 14 - or a piston 34 - And this leads to the above-described reduction of the chamber volume.

In short, the movement of the in 4 shown embodiment of the pump 10 to be described as follows:

During the forward stroke pulls the or each membrane 40 the drive rod 24 against the restoring force of the return element 28 , The return stroke is due to the or each membrane 40 applied electrical potential whose length and elasticity increases, so that the effect of the restoring force of the return element 28 outweighs and corresponding to the return element 28 the drive rod 24 deflects in the direction of the effect of the restoring force.

When cyclically applying an electrical potential to the or each membrane 40 results in a corresponding cyclical movement of the drive rod 24 and a concomitant cyclical movement of the chamber membrane 14 or a piston 34 , This leads to the known pumping action. The resulting stroke of the pump 10 is the distance H between the two parallel guides.

For a single membrane 40 in a, for example, cylindrical pump housing, the membrane engages 40 on the one hand on the outer surface of the drive rod 24 and on the other hand, for example, on the inner circumferential surface of the pump housing. The connection of the membrane 40 with the Pump housing can be made, for example, by the membrane 40 is fixed on the pump housing side between two components of the pump housing along the circumferential line of the pump housing or piecewise along this circumferential line by clamping. Alternatively, for example, sticking to the inner circumferential surface of the pump housing comes into consideration. Similarly, the connection of the membrane 40 with the drive rod 24 For example, be prepared by the membrane 40 between two parts of the drive rod 24 is trapped or by the membrane 40 on the drive rod 24 is glued on.

Alternatively to the in 4 embodiment shown, based on the same principle embodiment with reversed direction of the force effect is conceivable. Then, the or each membrane acts without an applied electric potential in the direction of a return stroke and the at an applied electric potential a prestroke causing restoring force (counterforce) is applied for example by means of acting as a compression spring plate or coil spring.

The representation in 5 shows an embodiment of a pump 10 on the in 4 shown embodiment, so that in order to avoid repetition on the basis of 4 explained details. In the embodiment according to 5 takes at least one additional electroactive membrane 40 ' the function of the reset element. For distinction, the or each membrane 40 , which applies or apply the force for the forward stroke, as Vorhubmembran 40 and the or each membrane 40 ' , which applies the force for the return stroke or apply, as Rückhubmembran 40 ' designated. The Vorhubmembran 40 is the membrane used in the 5 shown embodiment closer to the chamber membrane 14 lies as the return stroke membrane 40 ' , This order along the length of the drive rod 24 is not mandatory. It is essential that by means of at least one membrane 40 in a state not subjected to an electric potential, a force is applied to the drive rod 24 can be exercised, leading to a forward stroke of the pump 10 leads (Vorhubmembran 40 ) and that by means of at least one further membrane 40 ' in a state not subjected to an electric potential, a force is applied to the drive rod 24 can be exercised, which leads to a return stroke of the pump 10 (Rückhubmembran 40 ).

For an oscillating movement of the drive rod 24 and thus an oscillating movement of the chamber membrane 14 - or a piston 34 - For pump operation, the or each Vorhubmembran 40 as well as the or each return stroke membrane 40 ' alternately applied with an electrical potential, so that either the effective length of the Vorhubmembran alternately 40 is increased ( 5 , left), hence the force effect of the return stroke membrane 40 ' predominates and a return stroke results or the effective length of the return stroke membrane 40 ' is increased ( 5 , right), therefore the force effect of the Vorhubmembran 40 predominates and accordingly a Vorhub the pump 10 results.

So far, the explanation of the proposed innovation here is based on a particularly simple control of the or each electroactive membrane 40 . 40 ' he follows. Here is the respective membrane 40 or a membrane 40 . 40 ' either acted upon by the respective electrical potential or not subjected to an electrical potential. Of course, there is also the possibility that due to the respective electrical energy source available electrical potential to some extent only partially on an electroactive membrane 40 . 40 ' to apply.

For the in 4 As shown, this means that by means of the respective membrane or each shown there 40 adjustable electrical potential is adjustable, how far the drive rod 24 by means of the return element 28 can be withdrawn. The maximum deflection of the drive rod 24 during a return stroke determines the maximum volume of the pump chamber 12 , At a high electrical potential, a greater elongation of the or each membrane results 40 , so the drive rod 24 can be withdrawn accordingly far. At a lower electrical potential, less elongation of the or each membrane results 40 , so the drive rod 24 Accordingly, less can be withdrawn. At a higher electrical potential correspondingly results in a larger maximum chamber volume. This is thus by means of the respective applied electrical potential (in the context of the elasticity of the chamber membrane 14 or within the range of motion of the piston 34 ) adjustable. The resulting oscillation amplitude of the drive rod 24 determines the volume change of the pump chamber 12 and thus, for example, the volume (flow) of the per unit time (during a pump cycle, during a return stroke and a subsequent pre-stroke) by means of the pump 10 funded medium.

Advantageously, the length of a time unit, ie the duration of a pump cycle, can also be set precisely. For this, the illustrations in 6 and 7 refer. Thus, to set a duration of a pump cycle on the return stroke to the or each membrane 40 a potential according to a predetermined or predefinable first voltage profile 50 (Rückhubspannungsprofil 50 ) and, accordingly, during the forward stroke to the or each membrane 40 a potential according to a predetermined or predefinable second voltage profile 52 (Vorhubspannungsprofil 52 ). The prestroke and return stroke tension profile 50 . 52 can be symmetrical, as shown in the illustrations in 6 and 7 is shown. However, this is not necessary and the Vorhub- and Rückhubspannungsprofil 50 . 52 can also be different. The sum of a respective duration (t _R , t _V ) of the return stroke voltage profile 50 and the Vorhubspannungsprofils 52 determines the total duration of a pump cycle of the pump 10 and is, for example, by changing the pitch of the pre-lift and return lift tension profiles 50 . 52 adjustable.

Although in the presentation in 7 in the interest of simple conditions linear and monotonically increasing or decreasing return stroke and Vorhubspannungsprofile 50 , 52 can be any profile 50 . 52 For example, be composed of several piecewise straight sections, each with different slopes. Alternatively or additionally, it is also considered that at least individual sections of a profile 50 . 52 or both profiles 50 . 52 follow a mathematical function, for example a trigonometric function or an exponential function.

The representation in 7 shows a return stroke and a Vorhubspannungsprofil 50 , 52, which is essentially a turn on and off at the or each membrane 40 corresponds to applied potential. The time course of the change in the volume of the pump chamber 12 is then determined by the respective restoring force. Such profiles 50 . 52 can be realized very easily.

Generally, that in the in 4 for a return stroke, an electrical potential (V _back ) between a lower threshold (Vmin ≥ 0V) and an upper threshold (V _max ), for example, the maximum available due to the electrical energy source potential, to the or each membrane 40 is applied and for a forward stroke an electrical potential (V _Vor ) between the upper threshold (V _max ) and the lower threshold (Vmin) to the or each membrane 40 is applied: V _return = [V _min .. V _max ]; V _Vor = [V _max .. V _min ]. By selecting the lower and upper threshold (V _min and V _max ), the two outer vertices of the oscillating movement of the drive rod 24 and thus the pump stroke can be set exactly. This means an exact adjustability of the volume change of the pump chamber 12 during a pump cycle (return stroke and subsequent advance stroke). By selecting the duration (t _R ) of the return stroke and the choice of the duration (tv) of the forward stroke, the stroke frequency of the pump 10 be set exactly. By specifying the return stroke tension profile 50 and the specification of the Vorhubspannungsprofils 52 can change the time of the volume of the pump chamber 12 be set exactly during a pump cycle, optionally even for both Teilhube independently. All these settings can be combined with each other, but also individually usable, the latter for example by by the specification of the lower and upper threshold (V _min , V _max ) "only" the displacement of the pump 10 is set.

The explanations based on 6 and 7 apply accordingly also for in 5 shown embodiment of a pump 10 , Here, just as explained above, in addition also for the return stroke membrane acting as a return element 40 ' their respective effective force adjustable by a specification of the respective applied potential.

The representation in 8th shows an example of possible due to such adjustability resulting volumes of the pump chamber 12 at the end of a return stroke ( 8th : left) and at the end of a Vorhubs ( 8th : right). On the representation of electroactive membranes 40 has been omitted in the interest of clarity. Correspondingly mentally is at least one membrane 40 according to 4 or at least a Vorhubmembran 40 and at least one return stroke membrane 40 ' according to 5 to complete. In the illustrations in 8th above, the associated V _{max is} significantly larger than in the illustrations in 8th below. In the illustrations in 8th below the corresponding V _max corresponds approximately to the Vmin of the representations in 8th above.

The illustrations in 9 show a pump 10 with a piston 34 instead of the previously shown chamber membrane 14 , It has already been pointed out above that in the embodiments as well, a chamber membrane 14 is used as a means for periodically changing the volume of the pump chamber 12 show, instead of the local chamber membrane 14 always alternatively also a piston 34 as a means for periodically changing the volume of the pump chamber 12 comes into consideration. In 8th It has been shown that by specifying the electrical potential with which the or each membrane 40 or the or each forward and return stroke membrane 40 . 40 ' is applied, a middle position can be adjusted, around which the drive rod 24 and thus also the chamber membrane 14 (or a piston 34 ) oscillates. In contrast, in 9 shown by dashed lines shown lower (return stroke) and upper (Vorhub) piston positions that by specifying the electrical potential with which the or each membrane 40 or the or each forward and return stroke membrane 40 . 40 ' is applied, can also adjust the stroke volume. The two based from 8th and 9 illustrated settings are also combinable.

The representation in 10 finally shows a particular embodiment of a pump 10 based on the in 5 shown pump 10 , The special feature is that the at least one as Vorhubmembran 40 and the at least one as Rückhubmembran 40 ' functioning electroactive membrane cyclically acts either as an actuator or as a sensor. The function as an actuator has been described so far and due to the function as an actuator results in the oscillating movement of the drive rod 24 , The function as a sensor is based on the fact that by means of a capacitance measurement a measure of the respective aspect ratio (ratio of thickness to area) of the membrane 40 . 40 ' can be determined. The respectively determined capacity is a measure of the respective effective length of the membrane 40 , 40 'and thus a measure of the axial position of the drive rod 24 , The axial position of the drive rod 24 is again a measure of the position of the pump 10 , so that by means of a capacitance measurement position measurements are available, which are for a regulation of the pump 10 are usable. A particular embodiment of a pump 10 Accordingly, the previously proposed type consists in that by means of a capacitance measurement on at least one membrane 40 . 40 ' available position measurement a regulation of the position of the drive rod 24 (Attitude control) and / or a regulation of the speed of movement of the drive rod 24 (Speed control) takes place. In the illustration in 10 is the alternating function of the membranes 40 . 40 ' shown as an actuator or sensor, in addition to the lines 42, 44 for acting on the respective membrane 40 . 40 ' with an electrical potential other lines (measuring lines) 46 . 48 are shown for capacity measurement.

A membrane functioning in this sense at least temporarily as a sensor 40 , 40 'allows the detection of the movement sequence of the pump 10 and allows by means of a corresponding control, for example, operating modes of the pump 10 with constant pumping frequency, constant stroke, constant force, constant volume change of the pump chamber 12 over time. In addition, functional combinations of the aforementioned types of control are possible.

Individual aspects of the description presented here can be briefly summarized as follows: Indicated are a chamber pump 10 and a method of operation thereof. The chamber pump 10 includes a pump chamber in a conventional manner 12 , a chamber membrane 14 or a piston 34 as a means for changing the volume of the pump chamber 12 , as well as one for changing the volume of the pump chamber 12 at the chamber membrane 14 or the piston 34 attacking and axially movable drive rod 24 , The here proposed chamber pump 10 is characterized by the fact that these at least one as an actuator for influencing an axial position of the drive rod 24 acting and on the one hand on the drive rod 24 and on the other hand to a housing of the pump 10 attacking electroactive membrane 40 . 40 ' and that during operation of the chamber pump 10, the at least one electroactive membrane 40 . 40 ' for influencing an axial position of the drive rod 24 and to obtain a return stroke or a forward stroke of the chamber pump 10 is subjected to an electric potential.

LIST OF REFERENCE NUMBERS

10

Pump / chamber pump

12

pump chamber

14

chamber diaphragm

16

housing part

18.20

Valve

22

eccentric

24

driving rod

26

Kitchen sink

28

Spring element, return element

30

anchor

32

guide

34

piston

36, 38

(free)

40, 40 '

electroactive membrane

42, 44

Line (for applying an electroactive membrane with an electrical potential)

46, 48

Line (for capacitance measurement on an electroactive membrane)

50

Rückhubspannungsprofil

52

Vorhubspannungsprofil

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2004124384 A1 [0034]

Claims (15)

A chamber pump (10) having a pump chamber (12), a chamber diaphragm (14) or a piston (34) as a means for changing the volume of the pump chamber (12) and a volume of the pump chamber (12) on the chamber membrane (14) or the piston (34) engaging and axially movable drive rod (24), characterized by at least one act as an actuator for influencing an axial position of the drive rod (24) and on the one hand to the drive rod (24) and on the other hand to a housing of the pump (10). attacking electroactive membrane (40, 40 '). Chamber pump (10) after Claim 1 in which a force for deflecting the drive rod (24) in a first direction can be applied by means of the at least one electroactive membrane (40, 40 ') acting as an actuator, and the chamber pump (10) comprises a return element (28, 40') by means of which a force for the deflection of the drive rod (24) in a first direction opposite to the second direction can be applied. Chamber pump (10) after Claim 2 , with at least one further acting as an actuator electroactive membrane (40 '), which acts on the one hand on the drive rod (24) and on the other hand on a housing of the pump (10), as a return element. A chamber pump (10) according to one of the preceding claims, comprising at least one first electroactive membrane (40) functioning as an actuator and at least one second electroactive membrane (40 ') acting as an actuator, each on the drive rod (24) and on the housing of the actuator Attack chamber pump (10) and are intended to exert a force on the drive rod (24) in the axial direction of the drive rod (24), wherein the force exerted on the drive rod (24) by means of the or each first electroactive diaphragm (40) is directed anti-parallel to the force exerted on the drive rod (24) by means of the or each second electroactive diaphragm (40 '). Chamber pump (10) after Claim 4 wherein the or each first electroactive membrane (40) engages the drive rod (24) in front of the or each second electroactive diaphragm (40 ') from the end of the drive rod (24) engaging the chamber diaphragm (14) or piston (34) wherein the or each first electro-active membrane (40) in this direction acts on the drive rod (24) on the pump housing before its point of application and wherein the or each second electro-active membrane (40 ') in this direction behind its point of application on the drive rod (24 ) acts on the pump housing. A chamber pump (10) according to any one of the preceding claims, wherein the at least one electroactive diaphragm (40, 40 ') acts as a sensor for obtaining positional information regarding a position of the chamber diaphragm (14) or the piston (34). Chamber pump (10) after Claim 6 as well as one of Claims 4 or 5 wherein the at least one first electroactive membrane (40) and the at least one second electroactive membrane (40 ') act alternately as an actuator and as a sensor. Method for operating a chamber pump (10) having a pump chamber (12), a chamber membrane (14) or a piston (34) as means for changing the volume of the pump chamber (12) and a volume for changing the volume of the pump chamber (12) Chamber membrane (14) or the piston (34) engaging and axially movable drive rod (24), characterized in that at least one on the one hand to the drive rod (24) and on the other hand on a housing of the pump (10) acting electroactive membrane (40, 40 ' ) is acted upon to influence an axial position of the drive rod (24) and to obtain a return stroke or a Vorhubs the chamber pump (10) with an electric potential. Method according to Claim 8 wherein the chamber pump (10) comprises at least one return element (28, 40 '), wherein by means of the at least one electroactive membrane (40, 40') a force for the deflection of the drive rod (24) in a first direction is applied and wherein by means of at least one return element (28, 40 ') is applied a force for deflecting the drive rod (24) in a second direction opposite to the first direction. Method according to Claim 9 wherein the chamber pump (10) as a restoring element (28, 40 ') comprises at least one second on the one hand on the drive rod (24) and on the other hand on the housing of the pump (10) engaging electroactive diaphragm (40') and wherein the force for the deflection of the drive rod (24) in the second direction opposite to the first direction by means of the or each second electroactive membrane (40 ') is applied. Method according to Claim 10 in that the at least one first electroactive membrane (40) and the at least one second electroactive membrane (40 ') are acted upon alternately or out of phase with an electrical potential and act as actuators for obtaining an oscillating movement of the drive rod (24). Method according to one of Claims 10 or 11 , wherein the or each first electroactive membrane (40) is acted upon in accordance with a predetermined or predetermined first voltage profile (50) with an electric potential and the or each second electroactive membrane (40 ') in accordance with a predetermined or predetermined second voltage profile (52) with a electrical potential is applied. Method according to one of Claims 8 to 12 , wherein by means of at least one electroactive membrane (40, 40 ') in the form of a capacitance measurement position information with respect to a position of the chamber membrane (14) or the piston (34) is determined. Method according to Claim 10 . 11 or 12 , wherein the or a first electroactive membrane (40) is applied alternately with an electric potential or to obtain a position information whose capacity is measured and / or wherein the or a second electroactive membrane (40 ') is applied alternately with an electric potential or the Receipt of position information whose capacity is measured. Method according to Claim 13 or 14 , wherein the position information acts as an actual value for a control of the chamber pump (10).

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