Abstract
A chamber pump (10) and a method for operating same are provided. The chamber pump (10) includes a pump chamber (12), a chamber diaphragm (14) or a piston (34) as well as an axially movable driving rod (24) acting on the chamber diaphragm (14) or on the piston (34) for changing the volume of the pump chamber (12). The chamber pump (10) includes an electroactive diaphragm (40, 40), which acts as an actuator for influencing an axial position of the driving rod (24) and acts on the driving rod (24), on the one hand, and on a housing of the pump (10), on the other hand. An electric potential is applied to the electroactive diaphragm (40, 40) during the operation of the chamber pump (10) to influence an axial position of the driving rod (24) and to achieve a return stroke or a forward stroke of the chamber pump (10).
Claims
1. A chamber pump for use in a medical device or in a safety system, the chamber pump comprising: a chamber pump housing; a chamber diaphragm or a piston, the chamber diaphragm or the piston cooperating with the chamber pump housing to form a pump chamber with the chamber diaphragm or the piston changing the volume of the pump chamber; an axially movable driving rod acting on the chamber diaphragm or on the piston for changing the volume of the pump chamber; an electroactive diaphragm acting on the driving rod as an actuator for influencing an axial position of the driving rod to deflect the driving rod in a first direction, wherein the electroactive diaphragm acts with a driving force that is applied on the driving rod and on the chamber pump housing; and a resetting element applying a resetting force deflecting the driving rod in a second direction opposite to the first direction, wherein the resetting element comprises an additional electroactive diaphragm acting as an actuator on the driving rod and on a housing of the pump.
2. A chamber pump in accordance with claim 1, wherein the driving force exerted on the driving rod by the electroactive diaphragm is directed antiparallel to the resetting force exerted on the driving rod by the additional electroactive diaphragm.
3. A chamber pump in accordance with claim 2, wherein: the electroactive diaphragm acts on the driving rod at a location closer to the chamber diaphragm or the piston as compared to the additional electroactive diaphragm; the electroactive diaphragm acts on the chamber housing at a location closer to the chamber diaphragm or the piston than to a location the electroactive diaphragm acts on the driving rod; and the additional electroactive diaphragm acts on the driving rod at a location that is closer to the chamber diaphragm or the piston than a location at which the additional electroactive diaphragm acts on the chamber housing.
4. A chamber pump in accordance with claim 1, wherein the electroactive diaphragm forms a sensor for obtaining position information regarding a position of the chamber diaphragm or of the piston.
5. A chamber pump in accordance with claim 4, wherein the electroactive diaphragm and the additional electroactive diaphragm act alternatingly as actuator and as sensor.
6. A method for operating a chamber pump, the method comprising the steps of: providing the chamber pump, wherein the chamber pump comprises a chamber pump housing, a chamber diaphragm or a piston, the chamber diaphragm or the piston cooperating with the chamber pump housing to form a pump chamber with the chamber diaphragm or the piston changing the volume of the pump chamber, an axially movable driving rod acting on the chamber diaphragm or on the piston for changing the volume of the pump chamber, an electroactive diaphragm acting on the driving rod as an actuator for influencing an axial position of the driving rod to deflect the driving rod in a first direction, wherein the electroactive diaphragm acts with a driving force that is applied on the driving rod and on the chamber pump housing; and a resetting element applying a resetting force deflecting the driving rod in a second direction opposite to the first direction, wherein the resetting element comprises an additional electroactive diaphragm acting as an actuator on the driving rod and on a housing of the pump; and applying an electric potential to the electroactive diaphragm or to the additional electroactive diaphragm for influencing an axial position of the driving rod and for achieving a return stroke or a forward stroke of the chamber pump.
7. A method in accordance with claim 6, further comprising applying an electric potential to the electroactive diaphragm or to the additional electroactive diaphragm for influencing an axial position of the driving rod and for achieving the other of the return stroke or the forward stroke of the chamber pump; and alternating between or in a phase-shifted manner changing between the return stroke and the forward stroke for achieving an oscillating motion of the driving rod.
8. A method in accordance with claim 7, wherein the electric potential is applied to the electroactive diaphragm corresponding to a predefined or predefinable first voltage profile; and the electric potential is applied to the additional electroactive diaphragm corresponding to a predefined or predefinable second voltage profile.
9. A method in accordance with claim 7, wherein position information concerning a position of the chamber diaphragm or of the piston is determined by means of the electroactive diaphragm in a form of a capacitance measurement.
10. A method in accordance with claim 7, wherein: an electric potential is alternatingly applied to the electroactive diaphragm or a capacitance of said electroactive diaphragm is measured to obtain position information; or an electric potential is alternatingly applied to the additional electroactive diaphragm or a capacitance of said additional electroactive diaphragm is measured to obtain position information.
11. A method in accordance with claim 9, wherein the position information acts as an actual value for regulating the volume of the chamber pump.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] In the drawings:
[0031] FIG. 1 is a schematic sectional view showing a chamber pump with a crank drivel;
[0032] FIG. 2 is a schematic sectional view showing a chamber pump with an oscillating armature drive or with a spring as a resetting element;
[0033] FIG. 3 is a schematic view showing electroactive films and the result of an electric potential applied thereto;
[0034] FIG. 4 is a schematic sectional view showing a chamber pump according to an embodiment of the invention at an end of a return stroke (left) and at the end of a forward stroke (right);
[0035] FIG. 5 is a schematic sectional view showing a special embodiment of a chamber pump according to the invention;
[0036] FIG. 6 is a graph showing voltage profiles to be applied to an electroactive diaphragm for triggering a return stroke and a forward stroke;
[0037] FIG. 7 is a graph showing voltage profiles to be applied to an electroactive diaphragm for triggering a return stroke and a forward stroke;
[0038] FIG. 8 is a schematic sectional view showing different volumes of the pump chamber (partially defined by a chamber diaphragm) of the chamber pump as a result of different electric potentials;
[0039] FIG. 9 is a schematic sectional view showing different volumes of the pump chamber (partially defined by a piston) of the chamber pump as a result of different electric potentials; and
[0040] FIG. 10 is a schematic sectional view showing another special embodiment of a pump chamber being proposed here, in which electroactive films act either as actuator for triggering a return stroke or a forward stroke or as sensor for determining the position information of the pump.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0041] Referring to the drawings, the views in FIG. 1 and FIG. 2 show in a schematically simplified manner two embodiments of a chamber pump 1, which will hereinafter sometimes also be called pump 1 for short, which embodiments are basically known per se. Each pump 1 has a pump chamber 12, which is defined by an elastic diaphragm 14, on the one hand, and by a housing part 16 of a pump housing, on the other hand, with at least one respective inflow opening and outflow opening formed therein. The diaphragm 14 hereinafter called chamber diaphragm 14 for distinction is connected on the side to the housing part 16. A respective valve 18, 20, which releases or closes the inflow opening or outflow opening synchronously with the pump cycle, is associated with the inflow opening or each inflow opening as well as with the outflow opening or each outflow opening.
[0042] The pump cycle is obtained during the operation of the pump 1 on the basis of a respective drive of the pump 1. A rotating drive (crank drive), whose rotary motion is converted by means of a disk with an eccentrically arranged crank pin (eccentric disk 22) or the like into an oscillating, linear motion of a driving rod (connecting rod) 24 acting on the chamber diaphragm 14 in a manner known basically per se, is used as a drive in FIG. 1. FIG. 2 shows an electromagnetic drive (coil 26 with a driving rod 24 that is ferromagnetic in at least some sections), which acts directly on the driving rod 24 and likewise leads to an oscillating, linear motion of the driving rod 24 acting on the chamber diaphragm 14 together with a spring element 28 exerting a resetting force. A pump 1 of this type is called oscillating armature pump and the part of the driving rod 24 that is ferromagnetic in at least some sections is correspondingly called armature 30. The driving rod 24 is guided in a guide 32.
[0043] Based on the axially oscillating motion of the driving rod 24, the chamber diaphragm 14 is tensioned or released cyclically. The chamber diaphragm 14 is tensioned during the return stroke of the driving rod 24 and this results in an increase in the volume of the chamber 12. The chamber diaphragm 14 is released during the forward stroke of the driving rod 24, and this results in a reduction in the volume of the chamber 12. This correspondingly applies to a piston 34 (FIG. 9) driven by means of the driving rod 24. When the chamber volume is enlarged, a respective medium flows into the chamber 12 via the inflow opening or each inflow opening. At least part of the medium having flowed previously into the chamber 12 is displaced from the chamber 12 through the outflow opening or each outflow opening during the subsequent reduction of the chamber volume. The result is, in a manner known per se, a volume flow of the medium being delivered and/or a pressure reduction upstream of the pump 1 and/or a pressure increase downstream of the pump 1.
[0044] The view in FIG. 3 shows in a schematically simplified manner an electroactive diaphragm 40 (electroactive film 40). This may be an electroactive diaphragm 40 hereinafter also called diaphragm 40 for short in the form of an electroactive polymer (EAP) or of a dielectric elastomer (DEA). Both variants will always be implied below whenever the diaphragm 40 or a diaphragm 40 is mentioned.
[0045] Electroactive polymers and dielectric elastomers are basically known per se. A diaphragm 40or generally an electroactive diaphragm 40 -, which is formed from it is known to change its aspect ratio (ratio of thickness to area) as a function of an applied electric potential. In addition or as an alternative, the elasticity of such a diaphragm 40 can also be set, so that a rigid and inflexible or only slightly flexible diaphragm or an elastic, flexible diaphragm will be obtained depending on the applied potential, as this is described, for example, in US 2004/124384 A1 (US 2004/124384 A1 is incorporated by reference herein in its entirety).
[0046] A diaphragm 40, to which no electric potential is applied, is shown in the upper area of the view in FIG. 3. The same diaphragm 40 is shown directly under it in case of application of an electric potential. As can be seen, the thickness of the diaphragm 40 is reduced because of the application of an electric potential. The area of the diaphragm 40 has increased in the process. This can only be seen in the view in the form of an increase in the extension of the diaphragm 40 along one of the axes thereof, i.e., in the form of a change in length.
[0047] The application of an electric potential to a diaphragm 40 is shown in the view in FIG. 3 in the form of two lines 42, 44 acting on the diaphragm 40. The lines 42, 44 lead to an electric power source, not shown, so that an electric potential can be applied to the respective diaphragm 40 by means of the lines 42, 44. These lines 42, 44 are not shown in the case of a diaphragm 40 to which no electric potential is applied. These lines 42, 44 are, of course, actually present in a concrete embodiment of the invention described below regardless of whether or not an electric potential is applied to the diaphragm 40 in question. The application of an electric potential to a diaphragm 40 is controlled, for example, by means of a circuit component present in a circuit with the lines 42, 44, for example, by means of an electronic switch in the form of a transistor or the like, in a manner that is basically known per se. The Figures show features which are to be the interpreted that the circuit component has applied electric potential when the electric lines 42, 44 are visible, representing a diaphragm 40 to which an electric potential is applied, whereas no electric potential is applied to a diaphragm 40 in the figures that do not show such visible lines 42, 44 in the particular view shown.
[0048] The lower part of the view in FIG. 3 shows two diaphragms 40, which together form a diaphragm pair. In the released, i.e., potential-free state, these are arranged in the same plane next to each other and adjoining each other. A spring element is placed in the area in which the two diaphragms 40 adjoin each other. In case of a potential applied to the diaphragm 40, the modulus of elasticity of the two diaphragms 40 changes as well, and the diaphragms 40, which have become flexible because of the applied electric potential, are partly lifted by the spring element, as this is shown in the view being shown.
[0049] A special feature should be pointed out in the interpretation of the following figures based on the view in the lower part of FIG. 3. The following applies in case of diaphragms 40 belonging together in pairs, i.e., a diaphragm pair as in the view in the lower part of FIG. 3, or in case of a plurality of diaphragms 40 belonging together: Even if lines 42, 44 connected to a diaphragm are shown for one diaphragm 40 only in the interest of clarity of the view (and application of one electric potential is thus shown), this, i.e., the application of the electric potential, also applies to the other diaphragm 40 of the diaphragm or pair or to every other diaphragm 40 belonging to the diaphragms belonging together. Consequently, an electric potential is either applied always simultaneously or an electric potential is not applied to diaphragms 40 belonging together.
[0050] Based on the explanations given above on the basis of FIG. 3, the view in FIG. 4 shows a first embodiment of a pump 10 of the type according to the invention, wherein reference is made to the description of FIG. 1 regarding known components of the pump 1 which are also present in the pump 10 according to the invention.
[0051] The view in FIG. 4 shows on the left-hand side the driving rod 24 at the lower summit and on the right-hand side at the upper summit of the oscillating motion. A situation with a maximum volume of the chamber 12 is correspondingly shown on the left-hand side. When the chamber volume increases, the medium in question flows into the chamber 12 up to the shown position of the chamber diaphragm 14. By contrast, a situation with minimum volume of the chamber 12 is shown on the right-hand side. The medium in question is displaced from the chamber 12 during a reduction of the chamber volume up to the shown position of the chamber diaphragm 14.
[0052] The motion of the chamber diaphragm 14or alternatively the motion of a piston 34 (FIG. 9)arises from the oscillating motion of the driving rod 24 guided in a guide 32. However, the motion of the driving rod 24 does not arise now (contrary to the views in FIG. 1 and FIG. 2) any longer from a crank drive or a linear drive of the type shown in FIG. 1. Rather, the drive of the driving rod 24 takes place by means of at least one electroactive diaphragm 40 or of a plurality of electroactive diaphragms 40 distributed symmetrically around the driving rod 24 in the radial direction as well as by means of a resetting element acting in the opposite direction.
[0053] The diaphragm or each diaphragm 40 acts, on the one hand, on the outer surface of the driving rod 24 and, on the other hand, on a housing of the pump 10. In case of an electric potential applied to the diaphragm 40 or each diaphragm (FIG. 4: View on the left-hand side), the effective length of the diaphragm 40 or each diaphragm between the location at which it is arranged, for example, on the pump housing, on the one hand, and at the driving rod 24, on the other hand, increases. A resetting element 28 acting on the driving rod 24, for example, a spring element 28, especially a spring element 28 in the form of a coil spring acting as a tension spring, then deflects the driving rod 24 corresponding to the increased effective length of the diaphragm or each diaphragm 40, so that a return stroke of the driving rod 24 and correspondingly a return stroke of the chamber diaphragm 14 will occur. This leads to the above-described increase in the chamber volume. As soon as an electric potential is not applied any longer to the diaphragm 40 or each diaphragm (FIG. 4: View on the right-hand side), the originalshortereffective length of the diaphragm or each diaphragm 40 will be restored. The driving rod 24 is moved by means of the diaphragm or each diaphragm 40 in the direction of a forward stroke against the force of the resetting element 28. A forward stroke of the chamber diaphragm 14or of a piston 34will thus take place as well, and this leads to the reduction of the chamber volume, which was already described above.
[0054] In summary, the motion process of the embodiment of the pump 10 as shown in FIG. 4 can thus be described as follows: During the forward stroke, the diaphragm 40 or each diaphragm pulls the driving rod 24 against the resetting force of the resetting element 28. During the return stroke, the length and the elasticity of the diaphragm 40 is increased because of the electric potential applied to the diaphragm 40 or each diaphragm 40, so that the action of the restoring force of the resetting element 28 prevails and the resetting element 28 correspondingly deflects the driving rod 24 in the direction in which the resetting force acts.
[0055] The cyclical application of an electric potential to the diaphragm 40 or each diaphragm leads to a corresponding cyclical motion of the driving rod 24 as well as to a cyclical motion of the chamber diaphragm 14 or of a piston 34, which is associated therewith. This leads to the pumping effect known per se. The resulting stroke of the pump 10 is the distance between the two parallel auxiliary lines designated by H.
[0056] In case of an individual diaphragm 40 in a pump housing, which is, for example, cylindrical, the diaphragm 40 acts, on the one hand, on the outer surface of the driving rod 24 and, on the other hand, for example, on the inner jacket surface of the pump housing. The connection of the diaphragm 40 to the pump housing may be established, for example, by the diaphragm 40 being fixed by clamping on sides of the pump housing between two components of the pump housing along the circumferential line of the pump housing or in some sections along this circumferential line. For example, bonding to the inner jacket surface of the pump housing may be considered as an alternative. Very similarly, the connection of the diaphragm 40 to the driving rod 24 may be established, for example, by the diaphragm 40 being clamped between two parts of the driving rod 24 or by the diaphragm 40 being bonded to the driving rod 24.
[0057] As an alternative to the embodiment shown in FIG. 4, an embodiment based on the same principle with the action of the force transposed is conceivable. The diaphragm or each diaphragm to which no electric potential is applied now acts in the direction of a return stroke and the resetting force (opposing force) bringing about a forward stroke when an electric potential is applied is generated, for example, by means of a disk spring or coil spring acting as a compression spring.
[0058] The view in FIG. 5 shows an embodiment of a pump 10, which is based on the embodiment shown in FIG. 4, so that reference is made to the details explained on the basis of FIG. 4 to avoid repetitions. In the embodiment according to FIG. 5, at least one additional electroactive diaphragm 40 assumes the function of the resetting element. For distinction, the diaphragm 40 or each diaphragm, which applies the force for the forward stroke, is called forward stroke diaphragm 40, and the diaphragm 40 or each diaphragm, which applies the force for the return stroke, is called return stroke diaphragm 40. The forward stroke diaphragm 40 is the diaphragm that is located, on the whole, closer to the chamber diaphragm 14 than the return stroke diaphragm 40 in the embodiment shown in FIG. 5. This order along the longitudinal extension of the driving rod 24 is not obligatory. It is essential that in a state in which no electric potential is applied, a force be able to be exerted by means of at least one diaphragm 40 to the driving rod 24, which force leads to a forward stroke (actuating stroke) of the pump 10 (actuating/forward stroke diaphragm 40) and that in a state in which no electric potential is applied, a force be able to be exerted to the driving rod 24, which force leads to a return stroke of the pump 10 (return stroke diaphragm 40).
[0059] An electric potential is alternatingly applied to the forward stroke diaphragm 40 or each forward stroke diaphragm as well as the return stroke diaphragm 40 or each return stroke diaphragm for an oscillating motion of the driving rod 24 and hence for an oscillating motion of the chamber diaphragm 14or of a piston 34for the pump drive, so that the effective length of the forward stroke diaphragm 40 is either alternatingly increased (FIG. 5, left) and the action of the force of the return stroke diaphragm 40 prevails and a return stroke will result, or else the effective length of the return stroke diaphragm 40 is increased (FIG. 5, right), and the action of the force of the forward stroke diaphragm 40 accordingly prevails and a forward stroke of the pump 10 will correspondingly occur.
[0060] The invention being proposed here has hitherto been explained on the basis of an especially simple actuation of the electroactive diaphragm 40, 40 or each electroactive diaphragm. The respective electric potential is either applied or not applied here to the respective diaphragm 40 or a diaphragm 40, 40. It is, of course, also possible to apply the electric potential available based on the respective electric power source more or less only partly to an electroactive diaphragm 40, 40.
[0061] For the embodiment shown in FIG. 4, this means that the extent to which the driving rod 24 can be retracted by means of the resetting element 28 can be set by means of the particular electric potential applied to the diaphragm 40 or each diaphragm shown there. The maximum deflection of the driving rod 24 during a return stroke determines the maximum volume of the pump chamber 12. A high electric potential results in a greater increase in the length of the diaphragm 40 or each diaphragm, so that the driving rod 24 can be retracted to a correspondingly great extent. A lower electric potential results in a smaller increase in the length of the diaphragm 40 or each diaphragm, so that the driving rod 24 can be retracted to a correspondingly lower extent. A higher electric potential correspondingly results in a greater maximum chamber volume. This can thus be set by means of the respective applied electric potential (within the framework of the elasticity of the chamber diaphragm 14 or within the framework of the range of motion of the piston 34). The resulting oscillation amplitude of the driving rod 24 determines the change in the volume of the pump chamber 12 and hence, for example, the volume (flow) of the medium being delivered per unit of time (during a pump cycle; during a return stroke and a subsequent forward stroke) by means of the pump 10.
[0062] The duration of a unit of time, i.e., the duration of a pump cycle, can advantageously be set here precisely as well. Reference is made for this to the views in FIG. 6 and FIG. 7. Accordingly, to set a duration of a pump cycle, a potential according to a predefined or predefinable first voltage profile 50 (return stroke voltage profile 50) is applied to the diaphragm 40 or each diaphragm during the return stroke, and a potential according to a predefined or predefinable second voltage profile 52 (forward stroke voltage profile 52) is applied to the diaphragm 40 or each diaphragm during the forward stroke. The forward and return stroke voltage profiles 50, 52 may be symmetrical, as this is shown in the views in FIG. 6 and FIG. 7. However, this is not necessary, and the forward and return stroke voltage profiles 50, 52 may also be different. The sum of a particular duration (t.sub.R, t.sub.V) of the return stroke voltage profile 50 and of the forward stroke voltage profile 52 determines the overall duration of a pump cycle of the pump 10 and can be set, for example, by changing the slope of the forward stroke and return stroke voltage profiles 50, 52.
[0063] Even though linear and monotonically rising and falling return stroke and forward stroke profiles 50, 52 are shown in the view in FIG. 7 in the interest of simple conditions, each profile 50, 52 may be composed, for example, from a plurality of sections that are straight in sections with respective different slopes. As an alternative or in addition, it is also possible for at least individual sections of a profile 50, 52 or both profiles 50, 52 to follow a mathematical function, for example, a trigonometric function or an exponential function.
[0064] The view in FIG. 7 shows a return stroke voltage profile and a forward stroke voltage profile 50, 52, respectively, which corresponds essentially to the switching on and to the switching off of the potential applied to the diaphragm 40 or each diaphragm. The change over time in the volume of the pump chamber 12 is also determined by the respective resetting force. Such profiles 50, 52 can be embodied in an especially simple manner.
[0065] It is generally true that in the embodiment shown in FIG. 4, an electric potential (V.sub.Rtn) between a lower threshold value (V.sub.min>0 V) and an upper threshold value (V.sub.max), for example, the maximum available potential based on the electric power source, is applied to the diaphragm 40 or each diaphragm for a return stroke, and an electric potential (V.sub.Act) between the upper threshold value (V.sub.max) and the lower threshold value (V.sub.min) is applied to the diaphragm 40 or each diaphragm for a forward (actuating) stroke: V.sub.Rm=[V.sub.min . . . V.sub.max]; V.sub.Act=[V.sub.max . . . V.sub.min]. By selecting the lower and upper threshold values (V.sub.min and V.sub.max), the two outer summits of the oscillating motion of the driving rod 24 and hence the pump stroke can be set precisely. This means that the change in the volume of the pump chamber 12 can be set precisely during a pump cycle (return stroke and subsequent forward stroke). By selecting the duration (t.sub.R) of the return stroke and by selecting the duration (t.sub.V) of the forward stroke, the stroke frequency of the pump 10 can be set precisely. By predefining the return stroke voltage profile 50 and by predefining the forward stroke voltage profile 52, the change over time in the volume of the pump chamber 12 during the pump cycle can be set precisely, optionally even independently from one another for the two partial strokes. All these possibilities of setting may be combined with one another, but may also be used individually. The latter happens, for example, if only the stroke volume of the pump 10 is set by predefining the lower threshold value and the upper threshold value (V.sub.min, V.sub.max).
[0066] The explanations based on FIG. 6 and FIG. 7 correspondingly also apply to the embodiment of a pump 10, which is shown in FIG. 5. Just as this was explained above, the respective effective force of the return stroke diaphragm 40 can also be set additionally for said return stroke diaphragm acting as a resetting element by predefining the respective applied potential.
[0067] The view in FIG. 8 shows as examples of this possible volumes of the pump chamber 12 resulting from such a possibility of setting at the end of a return stroke (FIG. 8; left) and at the end of a forward stroke (FIG. 8; right). Electroactive diaphragms 40 are not shown here in the interest of clarity. At least one diaphragm 40 according to FIG. 4 or at least one forward stroke diaphragm 40 as well as at least one return stroke diaphragm 40 according to FIG. 5 may correspondingly be added conceptually. In the views in the upper part of FIG. 8, the corresponding V.sub.max is markedly greater than in the views in the lower part of FIG. 8. In the views in the lower part of FIG. 8, the corresponding V.sub.max approximately corresponds to the V.sub.min in the views in the upper part of FIG. 8.
[0068] The views in FIG. 8 show a pump 10 with a piston 34 instead of the chamber diaphragm 14 shown hitherto. It was already mentioned farther above that a piston 34 may also always be considered for use as an alternative as a means for periodically changing the volume of the pump chamber 12 even in the embodiments that show a chamber diaphragm 14 as a means for periodically changing the volume of the pump chamber 12 instead of the chamber diaphragm 14 used there. It was shown in FIG. 8 that by predefining the electric potential, which is applied to the diaphragm 40 or each diaphragm or to the forward stroke diaphragm 40, 40 or each forward stroke diaphragm, a middle position can be set, around which the driving rod 24 and hence also the chamber diaphragm 14 (or a piston 34) oscillates. By contrast, it is shown in FIG. 9 by means of lower (return stroke) and upper (forward stroke) piston positions, which are drawn by broken lines, that the stroke volume can also be set by predefining the electric potential, which is applied to the diaphragm 40 or each diaphragm or to the forward stroke diaphragm and the return stroke diaphragm 40, 40 or to each diaphragm. The two possibilities of setting shown on the basis of FIG. 8 and FIG. 9 may, moreover, also be combined.
[0069] The view in FIG. 10 finally shows a special embodiment of a pump 10 on the basis of pump 10 shown in FIG. 5. The special feature is that the at least one electroactive diaphragm acting as a forward stroke diaphragm 40 and the at least one electroactive diaphragm acting as a return stroke diaphragm 40 act cyclically either as an actuator or as a sensor. The function as an actuator has been described so far and the oscillating motion of the driving rod 24 arises from the function as an actuator. The function as a sensor is based on the fact that an indicator can be determined for the respective aspect ratio (ratio of thickness to area) of the diaphragm 40, 40 by means of a capacitance measurement. The particular capacitance determined as an indicator of the respective effective length of the diaphragm 40, 40 and hence also an indicator of the axial position of the driving rod 24. The axial position of the driving rod 24 is, in turn, an indicator of the position of the pump 10, so that position measured values, which can be used for regulating the pump 10, can be obtained by means of a capacitance measurement. A special embodiment of a pump 10 of the type proposed so far is correspondingly based on the fact that the position of the driving rod 24 is regulated (position regulation) and/or the speed of motion of the driving rod 24 (speed regulation) is regulated by means of a position measured value that can be obtained based on capacitance measurement on at least one diaphragm 40, 40. The alternating function of the diaphragms 40, 40 as an actuator or sensor is shown in the view shown in FIG. 10 by showing additional lines (measuring lines) 46, 48 for capacitance measurement in addition to the lines 42, 44 for applying an electric potential to the respective diaphragm 40, 40.
[0070] A diaphragm 40, 40 acting at least at times as a sensor in this sense makes it possible to detect the motion process of the pump 10 and makes possible, for example, modes of operation of the pump 10 with constant pump frequency, constant stroke, constant force, and constant change in the volume of the pump chamber 12 over time by means of a corresponding regulation. In addition, functional combinations of the above-mentioned modes of regulation are also possible.
[0071] Individual aspects of the description submitted here, which are in the foreground, can thus be summed up briefly as follows: Proposed are a chamber pump 10 and a method for operating same. The chamber pump 10 comprises, in the manner known per se, a pump chamber 12, a chamber diaphragm 14 or a piston 34 as means for displacing the volume of the pump chamber 12, as well as a driving rod 24, which is axially movable and acts on the chamber diaphragm 14 or on the piston 34 to change the volume of the pump chamber 12. The chamber pump 10 being proposed here is characterized in that it comprises at least one electroactive diaphragm 40, 40, which acts as an actuator for influencing an axial position of the driving rod 24 and acts on the driving rod 24, on the one hand, as well as on a housing of the pump 10, on the other hand, and that an electric potential is applied to the at least one electroactive diaphragm 40, 40 during the operation of the chamber pump 10 to influence an axial position of the driving rod 24 and to achieve a return stroke or a forward stroke of the chamber pump 10.
[0072] While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.
APPENDIX:
LIST OF REFERENCE DESIGNATIONS
[0073] 1 Pump/chamber pump [0074] 10 Pump/chamber pump [0075] 12 Pump chamber [0076] 14 Chamber diaphragm [0077] 16 Housing part [0078] 20 Valve [0079] 22 Eccentric disk [0080] 24 Driving rod [0081] 26 Coil [0082] 28 Spring element, resetting element [0083] 30 Armature [0084] 32 Guide [0085] 34 Piston [0086] 36, 38 (Blank) [0087] 40, 40 Electroactive diaphragm [0088] 42, 44 Line (for applying an electric potential to an electroactive diaphragm) [0089] 46,48 Line (for capacitance measurement on an electroactive diaphragm) [0090] 50 Return stroke voltage profile [0091] 52 Forward stroke voltage profile
