Balance chamber system for a dialysis machine with a dialyzer for extracorporeal blood treatment

Description

[0001] The invention relates to a balancing chamber system according to the preamble of claim 1 for a dialysis machine.

[0002] A balancing chamber system is known from DE 10 2017 125 962 A1 and is recognized therein as state of the art. The known balancing chamber system is intended for a dialysis machine with a dialyzer for extracorporeal blood treatment. During such blood treatment, blood is conducted in an extracorporeal blood circuit through a blood chamber of the dialyzer. The blood chamber is separated from a dialysis fluid chamber of the dialyzer by a semipermeable membrane, through which a dialysis fluid flows. Urinary substances from the blood diffuse across the semipermeable membrane from the blood chamber into the dialysis fluid chamber, while at the same time electrolytes present in the blood and dialysis fluid diffuse from the chamber with a higher concentration to the chamber with a lower concentration. In addition, so-called ultrafiltration may be desired, in which fluid is removed from the blood for the purpose of dehydration.It is of crucial importance that this fluid withdrawal is balanced, because even a slightly excessive fluid withdrawal can have serious medical consequences. The known balancing chamber system is used for such balancing and has a balancing chamber unit - in a ready-to-use state - fluidically connected to the dialyzer with a first balancing chamber and a second balancing chamber. The first balancing chamber is intended for the reception and discharge of dialysis fluid from the fresh flow side and is connected to an inlet of the dialyzer. The second balancing chamber is intended for the reception and discharge of dialysis fluid from the waste flow side and is connected to an outlet of the dialyzer. The first balancing chamber and the second balancing chamber are fluid-tightly separated from one another and volumetrically coupled by means of a membrane unit that can be deflected between different deflection positions.As a result of the volumetric coupling, when the membrane unit receives a volume of fresh-stream dialysis fluid in the first balancing chamber, it displaces a corresponding volume of waste-stream dialysis fluid from the second balancing chamber, and vice versa. To alternately fill and empty the balancing chambers—and thus to convey the dialysis fluid—the known balancing chamber system features a complex arrangement comprising a fresh-stream pump, a second waste-stream pump, and switching valves arranged on the inlet and outlet sides of the balancing chambers.

[0003] Furthermore, DE 10 2014 218 981 A1 discloses a pressure generating device for use in a braking system of a motor vehicle, physically functioning as a balancing chamber system. The known pressure generating device has at least one fluid pressure chamber located in a working chamber and an actuator made of an electroactive material, which is variable in its length and cross-sectional area and is positioned in the fluid pressure chamber. The remaining space of the fluid pressure chamber, less the inserted actuator, defines a fluid space for a fluid. The actuator causes a change in the volume of the fluid space by means of a combination of a change in length and a change in the cross-sectional area. The change in volume leads to the generation of a force on the fluid. This force can be used to suck in the fluid or to expel it from the space.

[0004] Furthermore, US 2007 / 164641 A1 discloses pumping devices with at least one electroactive polymer converter. The electroactive polymer converter can be in contact with a fluid and perform thermodynamic work on the fluid. The known pumping devices can be used in particular in cooling systems and heating systems. Use in dialysis machines is also generally described.

[0005] The object of the invention is to provide a balancing chamber system of the type mentioned above, which has a simplified structure compared to the prior art.

[0006] This object is achieved by providing a balancing chamber system with the features of claim 1. The solution according to the invention makes it possible, in particular, to dispense with separate fresh and used flow side pumps for filling and emptying the balancing chambers. This makes it possible to achieve a simplified structure of the balancing chamber system and ultimately saves costs in production, assembly and / or maintenance. Instead of two such pumps, the invention provides at least one actuator element formed from the dielectric elastomer material, which can also be referred to as a dielectric elastomer actuator. Such actuators, their basic structure and the underlying functional principle for converting electrical energy into mechanical energy are generally known in the field of drive technology.The basic structure of such a dielectric elastomer actuator comprises a passive elastomer film, the top and bottom of which are each coated with a compliant electrode. When an electrical voltage is applied to the opposing electrodes, they attract each other due to electrostatic forces. This compresses the elastomer film in the thickness direction and expands it laterally. When the voltage is removed, the elastomer film returns to its original state of laterally contracted and thickness expanded. Based on this functional principle, the actuating movement for deflecting the diaphragm unit can be generated. The elastomer film can be made of silicone or acrylic, in particular. The electrodes can be made of graphite powder, a silicone oil-graphite mixture, or gold.Based on the basic structure described above, the at least one actuator element can be designed in particular in the form of a planar actuator, stack actuator, bundle actuator, rolling actuator or shell actuator. The aforementioned designs are generally known as such, so that further explanations in this regard are omitted. The at least one actuator element can in particular be integrated into the membrane unit or arranged away from the membrane unit and mechanically coupled to it. It is understood that the first balancing chamber and the second balancing chamber each have an inlet and an outlet fluidically connected to the inlet. The inlet of the first balancing chamber is connected to a source of dialysis fluid in the assembled, ready-to-use state. The outlet of the first balancing chamber is intended for connection to an inlet of a dialysis fluid chamber of the dialyzer.The inlet of the second balancing chamber is designed for connection to an outlet of the dialysis fluid chamber of the dialyzer. The outlet of the second balancing chamber, when assembled and ready for operation, is connected to an outlet for the disposal and / or processing of the dialysis fluid. The balancing chamber system can preferably have a second balancing chamber unit which is arranged parallel to the first balancing chamber unit in a fluid-conducting manner on both the fresh and used flow sides. This allows continuous pumping of the dialysis fluid through the dialyzer. The dialysis fluid chamber comprises those fluid-conducting sections of the dialyzer through which dialysis fluid flows. Those fluid-conducting sections of the dialyzer through which blood flows can be referred to as the blood chamber. The dialysis fluid can also be referred to as the dialysate.

[0007] In one embodiment of the invention, the at least one actuator element is configured for capacitive detection of the deflection position of the membrane unit and thus additionally functions as a sensor element. The above-described change in the geometry of the at least one actuator element under the influence of the electrical voltage simultaneously causes a change in capacitance, which can be used for sensory purposes, for example, for pressure and / or displacement measurement. Accordingly, the at least one actuator element in this embodiment of the invention performs a particularly advantageous multiple function. As a result, a separate sensor system for detecting the deflection position of the membrane unit can be dispensed with, thereby achieving a further simplified structure of the balancing chamber system.

[0008] In a further embodiment of the invention, at least one spring element is operatively connected to the diaphragm unit and the actuator element, wherein the diaphragm unit - when an electrical voltage is applied to the actuator element - is deflected in a first direction by means of the spring element, and wherein the diaphragm unit - when the electrical voltage is reduced - is deflected by means of the actuator element against the action of the spring element in a second direction opposite to the first direction. This embodiment of the invention achieves a deflection of the diaphragm unit in two directions, namely the first direction and the second direction, using structurally simple means. For this purpose, the spring element is provided and operatively connected to the diaphragm unit in a parallel circuit to the actuator element. The spring element can in particular be designed as a helical or leaf spring and made of metal or plastic.The spring element can be integrated into the diaphragm unit. Alternatively, the spring element can be arranged away from the diaphragm unit and be mechanically connected to the diaphragm unit. Preferably, the at least one spring element is supported on a bearing section of the balancing chamber unit, which can be assigned to the first balancing chamber and / or the second balancing chamber.

[0009] Further according to the invention, the membrane unit has a first membrane delimiting the first balancing chamber and a second membrane delimiting the second balancing chamber, wherein the first membrane and the second membrane are operatively connected to one another for the volumetric coupling of the first balancing chamber and the second balancing chamber by means of a rigid coupling element and / or an incompressible coupling fluid. Such a configuration can be particularly advantageous if, due to installation space constraints, the first balancing chamber and the second balancing chamber cannot be arranged directly adjacent to one another in an installation space available on the device side. In order to nevertheless ensure the volumetric coupling between the first balancing chamber and the second balancing chamber required for balancing, the coupling element and / or the coupling fluid are provided.The coupling element and / or the coupling fluid form an operative connection between the first and second membranes. The rigid coupling element is supported at one end on the first membrane and the other end on the second membrane, such that a deflection of the first membrane is transmitted to the second membrane by means of the coupling element and vice versa. The coupling fluid can be filled into a receiving space arranged between the first and second membranes. To ensure a deflection of the same volume of both membranes, the coupling fluid is incompressible and can be, for example, water, oil, silicone, or a mixture formed from at least two of the aforementioned fluids. The at least one actuator element can be integrated into the first membrane or the second membrane. Alternatively, two actuator elements can be provided, with one of the actuator elements being integrated into each of the membranes.Further alternatively, the at least one actuator element can be arranged away from both membranes and mechanically operatively connected to at least one of the membranes. Alternatively, a mechanical operative connection to both membranes can be provided. If a spring element connected in parallel to the at least one actuator element is provided, the statements regarding the at least one actuator element apply accordingly with regard to its integration or remote arrangement.

[0010] In a further embodiment of the invention, a single actuator element is provided, the actuating movement of which is transmitted between the first membrane and the second membrane by means of the coupling element and / or the coupling fluid. This embodiment of the invention enables the deflection of both membranes using only one actuator element, thus achieving a simple design.

[0011] In a further embodiment of the invention, the at least one actuator element in the form of at least one active membrane layer is integrated into the membrane unit, in particular into the first membrane and / or the second membrane. This is a particularly advantageous embodiment of the invention since installation space can be saved, in particular compared to an arrangement of the at least one actuator element away from the membrane unit. In this embodiment of the invention, the at least one actuator element is therefore preferably in the form of a planar or stacked actuator. In the former case, a single elastomer layer coated with electrodes on the top and bottom is provided. In the latter case, several planar actuators are stacked on top of one another, whereby comparatively greater actuating forces and / or actuating movements can be achieved.

[0012] In a further embodiment of the invention, the active membrane layer is protected from wetting with the dialysis fluid by means of at least one further membrane layer and / or a coating. This embodiment of the invention prevents undesired chemical and / or electrochemical reactions between the active membrane layer and the dialysis fluid. The further membrane layer and / or coating can be made in particular of silicone. Preferably, the active membrane layer is arranged between two further membrane layers or coated on both sides. Preferably, the at least one actuator element or the active membrane layer is encapsulated with silicone to form the membrane unit or one of the membranes of the membrane unit.

[0013] In a further embodiment of the invention, at least one sensor layer made of a dielectric elastomer material is integrated into the membrane unit, wherein the at least one sensor layer is configured to detect a pressure prevailing in the first balancing chamber and / or the second balancing chamber. This is a particularly preferred embodiment of the invention. The at least one sensor layer eliminates the need for a sensor system separate from the membrane unit for detecting the pressure in the first balancing chamber and / or the second balancing chamber. Instead, the at least one sensor layer is provided for such pressure detection and is integrated into the membrane unit. When the pressure increases, the capacitance of the at least one sensor layer changes. This occurs due to the dielectric properties of the elastomer material of the at least one sensor layer. The pressure can be determined depending on the change in capacitance.

[0014] In a further embodiment of the invention, the at least one actuator element is arranged in the form of a linear actuator with a translational actuating movement away from the membrane unit. Accordingly, in this embodiment of the invention, the at least one actuator element is not integrated into the membrane unit. Instead, the at least one actuator element acts on the membrane unit, so to speak, from the outside. Furthermore, a design of the at least one actuator element as a linear actuator is provided, which is configured to execute a translational actuating movement. For this purpose, the linear actuator can in particular be a bundle actuator comprising several stack actuators.

[0015] In a further embodiment of the invention, the balancing chambers each have an inlet and an outlet, with a check valve being provided for flow control through the respective inlet or outlet. This is a particularly preferred embodiment of the invention. In contrast, the prior art mentioned at the outset requires switching valves for flow control. The solution according to the invention eliminates the need for such switching valves for flow control. Instead, comparatively simple, cost-effective check valves are sufficient. The check valves can, in particular, each be designed as a poppet valve.

[0016] The invention also relates to a dialysis machine with a dialyzer for extracorporeal blood treatment, wherein a balancing chamber system according to one of the preceding claims is fluidically connected to a dialysis fluid chamber of the dialyzer.

[0017] Furthermore, an actuator element formed from the dielectric elastomer material can be assigned to a hose clamp and / or a shut-off valve of the dialysis machine. In this case, the actuator element can, under the influence of the electrical voltage, cause an actuating movement to actuate the hose clamp or the shut-off valve.

[0018] Further advantages and features of the invention emerge from the claims and from the following description of preferred embodiments of the invention, which are illustrated with reference to the drawings. Fig. 1 shows a schematic representation of a section of a dialysis machine known from the prior art, which is provided with a balancing chamber system known from the prior art, Fig. 2 shows a schematic representation of a section of an exemplary embodiment of a simplified dialysis machine which is provided with an embodiment of a balancing chamber system according to the prior art according to DE 10 2014 218 981 A1 (see above), Fig. 3 shows a schematically greatly simplified exemplary representation of a balancing chamber unit of the in Fig. 2 shown balancing chamber system, Fig. 4 in schematically highly simplified exemplary cross-sectional representation a section of a membrane unit of the balancing chamber system according to Fig. 3 in an area IV, Fig. 5in one of the Fig. 3 corresponding representation an inventive design of a balancing chamber unit for the balancing chamber system according to Fig. 2 , Fig. 6in one of the Fig. 3corresponding representation a further inventive embodiment of a balancing chamber unit for the balancing chamber system according to Fig. 2 , Fig. 7in one of the Fig. 3 corresponding representation a further exemplary embodiment, not according to the invention, of a balancing chamber unit for the balancing chamber system according to Fig. 2 , Fig. 8in one of the Fig. 3 corresponding representation a further inventive embodiment of a balancing chamber unit for the balancing chamber system according to Fig. 2 , Fig. 9in one of the Fig. 3 corresponding representation a further inventive embodiment of a balancing chamber unit for the balancing chamber system according to Fig. 2 , Fig. 10in one of the Fig. 3 corresponding representation a further inventive embodiment of a balancing chamber unit for the balancing chamber system according to Fig. 2, Fig. 11 in a schematically simplified perspective view a further embodiment of a balancing chamber unit according to the invention for the balancing chamber system according to Fig. 2 in the direction of view of a membrane unit and Fig. 12 a schematically simplified representation of a layer structure of the membrane unit according to Fig. 11 . Fig. 1 shows a schematically highly simplified representation of a section of a dialysis machine 101 known from the prior art, which is intended for extracorporeal blood treatment and has a dialyzer 102 with a blood chamber 103 and a dialysis fluid chamber 104. The blood chamber 103 is separated from the dialysis fluid chamber 104 by means of a semipermeable membrane 105 and is fluidically connected to an unspecified extracorporeal blood circuit with a Fig. 1 The dialysis machine 101 is connected to the dialysis fluid chamber 104 in the direction of flow BF of the blood to be treated. Furthermore, the known dialysis machine 101 has a balancing chamber system 106 known from the prior art, which is fluidically connected to the dialysis fluid chamber 104.

[0019] The known balancing chamber system 106 serves, in a manner known to those skilled in the art, for volumetric balancing of a dialysis fluid passed through the dialyzer 102, which during operation of the dialysis machine 101 is guided along a Fig. 1 indicated flow direction DF.

[0020] The known balancing chamber system 106 has a first balancing chamber unit 107 with a first balancing chamber 108 and a second balancing chamber 109. The first balancing chamber 108 and the second balancing chamber 109 are fluid-tightly separated from one another and volumetrically coupled to one another by means of a membrane unit 110 that can be deflected between different deflection positions. The first balancing chamber 108 is provided for receiving and discharging dialysis fluid from the fresh flow side and can therefore also be referred to as the fresh flow side first balancing chamber 108. The second balancing chamber 109, in contrast, is provided for receiving and discharging dialysis fluid from the waste flow side and can therefore also be referred to as the waste flow side second balancing chamber 109. A pump is provided to fill each of the first balancing chamber 108 and the second balancing chamber 109, namely a fresh flow side first pump P1 and a waste flow side second pump P2.Furthermore, the known balancing chamber system 106 has valves V1, V2, V3, V4 for controlling the flow of the dialysis fluid through the first balancing chamber 108 and the second balancing chamber 109, which are connected to the inlet and outlet sides of the balancing chambers 108, 109, respectively, and are designed as switching valves. To stabilize the delivery of the dialysis fluid, the known balancing chamber system has a second balancing chamber unit 111 with a third balancing chamber 112 and a fourth balancing chamber 113, which are fluid-tightly separated from one another by means of a further membrane unit 114 and volumetrically coupled to one another. The third balancing chamber 112 is connected in parallel to the first balancing chamber 108 on the fresh flow side and can be filled by the first pump P1. The fourth balancing chamber 113 is connected in parallel to the second balancing chamber 109 on the used flow side and can be filled by the second pump P2.For flow control, valves V5, V6, V7, V8 are provided in a manner corresponding to the first balancing chamber unit 107.

[0021] The function of the balancing chamber system 106 is divided into two phases.

[0022] In a first phase, the following starting conditions are present: First balance chamber 108 empty, second balance chamber 109 full, the membrane unit 110 takes a - with respect to the plane of the drawing of the Fig. 1- deflection position deflected to the left, third balancing chamber 112 full, fourth balancing chamber 113 empty, the membrane unit 114 assumes a deflection position deflected to the right. The valves are switched as follows: V1 closed, V2 open, V3 open, V4 closed, V5 closed, V6 open, V7 open, V8 closed. The first pump P1 thus fills the first balancing chamber 108 through valve V3 with fresh dialysis fluid, which can be taken from a source Q, for example. As a result, used dialysis fluid, which is located in the second balancing chamber 109 and can also be referred to as dialysate, is drained through valve V2 into a corresponding outlet A. At the same time, the second pump P2 fills the fourth balancing chamber 113 with used dialysis fluid through valve V6. As a result, fresh dialysis fluid, which is located in the third balancing chamber 112, is fed to the dialyzer 102 through valve V7.

[0023] In a second phase, the following starting conditions exist: second balancing chamber 109 empty, first balancing chamber 108 full, the membrane unit 110 assumes a deflection position deflected to the right, fourth balancing chamber 113 full, third balancing chamber 112 empty, the membrane unit 114 assumes a deflection position deflected to the left. The valves are switched as follows: V1 open, V2 closed, V3 closed, V4 open, V5 open, V6 closed, V7 closed, V8 open. The first pump P1 thus fills the third balancing chamber 112 with fresh dialysis fluid through valve V5. As a result, used dialysis fluid in the fourth balancing chamber 113 is directed through valve V8 into spout A. Simultaneously, the second pump P1 fills the second balancing chamber 109 with used dialysis fluid through valve V4.As a result, fresh dialysis fluid located in the first balance chamber 108 is conveyed through the valve V1 to the dialyzer 102.

[0024] The alternating switching of the valves takes place in particular depending on the respective deflection position of the membrane units 110, 114. For their metrological detection, the embodiment shown, known from the prior art, provides sensor units SE1, SE2, which are each designed as inductive membrane sensors and are assigned to one of the balancing chamber units 107, 108.

[0025] Furthermore, the known balancing chamber system 106 has an ultrafiltration pump P3 arranged on the demand flow side, which forms a hydraulic short circuit between the balancing chamber units 107, 111 and serves for a defined withdrawal of dialysis fluid from the closed balance chamber-side circuit.

[0026] The above-described structure of the known balancing chamber system 106 is complex and has disadvantages, particularly with regard to its assembly, maintenance, and / or repair. This is particularly due to the pumps P1, P2, the individually controlled valves V1 to V8, and the separate sensor units SE1, SE2.

[0027] Fig. 2 shows in a schematically highly simplified representation a section of an exemplary embodiment of a dialysis machine 1, which has an embodiment of a dialysis machine known from the above-mentioned prior art according to DE 10 2014 218 981 A1

[0028] balancing chamber system 6. The dialysis machine 1 has, in a manner corresponding to the known dialysis machine 101, a dialyzer 2 with a blood chamber 3, a dialysis fluid chamber 4, and a semipermeable membrane 5. To avoid repetition, reference is made to the relevant description in connection with Fig. 1which, with regard to Fig. 2 applies accordingly.

[0029] The balancing chamber system 6 comprises a balancing chamber unit 7 with a first balancing chamber 8 and a second balancing chamber 9, which are fluid-tightly separated from one another and volumetrically coupled to one another by a membrane unit 10 that can be deflected between different deflection positions. The first balancing chamber 8 is arranged on the fresh flow side and is thus intended for receiving and discharging dialysis fluid from the fresh flow side. The second balancing chamber 9, in contrast, is arranged on the waste flow side and is thus intended for receiving and discharging dialysis fluid from the waste flow side.

[0030] To stabilize the delivery of the dialysis fluid through the dialysis fluid chamber 4, the balancing chamber system 6 has - in a manner fundamentally corresponding to the known balancing chamber system 106 - a second balancing chamber unit 11, which in the embodiment shown is structurally identical to the balancing chamber 7. In this respect, the balancing chamber unit 7 can also be referred to here as the first balancing chamber unit. However, such a configuration with a first balancing chamber unit 7 and a second balancing chamber unit 11 is not mandatory. Accordingly, an embodiment of the balancing chamber system (not shown) has only a single balancing chamber unit. Before the further structure and functioning of the balancing chamber system 6 are explained in detail, the following will be explained, in particular with reference to the Fig. 3 to 12 the design of the balancing chamber unit 7 was discussed.

[0031] Based on the exemplary illustrations in the Figs. 3 and 4It is shown that an actuator element E is provided for deflecting the membrane unit 10 and thus for conveying the dialysis fluid. The actuator element E is formed from a dielectric elastomer material M ( Fig. 4 Dielectric elastomer materials for converting electrical energy into mechanical work and the underlying operating principles are known as such. The actuator element E in the embodiment according to the Figs. 3 and 4 integrated into the membrane unit 10 and thus forms an active membrane layer ES of the membrane unit 10 ( Fig. 4 ).

[0032] Under the influence of an electrical voltage, the actuator element E, which can also be referred to as a dielectric elastomer actuator, carries out a Fig. 4When an electrical voltage is applied, the elastomer material M is compressed in the thickness direction of the membrane unit 10 and thereby expanded in its area; when this voltage is reduced and / or in a tension-free state, the elastomer material M elastically returns to its original position, so that an adjusting movement R along the Fig. 4 This allows a deflection of the membrane unit 10 along the direction shown in Fig. 3 The indicated direction arrows are possible. The said electrical voltage can be applied via electrodes 15, 16 applied to the front and back of the dielectric elastomer material M, which can be electrically connected in a generally known manner to voltage lines 17, 18 of a switching and / or control circuit not shown in detail.

[0033] In order to avoid direct contact of the active membrane layer ES with the dialysis fluid, the membrane unit 10 in the embodiment shown has further membrane layers, namely a first membrane layer 19 and a second membrane layer 20. The active membrane layer ES is arranged in the thickness direction of the membrane unit 10 between the first membrane layer 19 and the second membrane layer 20. It is understood that the Fig. 4 The dimensions shown in the thickness direction of the membrane unit 10 are purely exemplary and not to scale.

[0034] The exemplary embodiment according to the Figs. 3 and 4also has a spring element 21 which is operatively connected to the membrane unit 10 and thus also to the actuator element E integrated therein. For this purpose, the spring element 21 is supported at one end on a housing (not designated in more detail) of the balancing chamber unit 7. The other end of the spring element 21 is supported on the membrane unit 10. In the present case, the spring element 21 acts on an anchor plate 22 of the membrane unit 10, which is firmly connected to the membrane layers 19, 20, ES in a basically known manner and is of comparatively rigid design. In the embodiment shown, the spring element 21 is designed as a helical spring. In an embodiment not shown, the spring element is instead designed as a leaf spring. The leaf spring is integrated into the membrane unit.

[0035] In the Fig. 3In the state shown, the membrane unit 10 is arranged approximately centrally between the first balancing chamber 8 and the second balancing chamber 9 and is deflected only slightly to the right. To deflect the membrane unit 10 and thus to convey the dialysis fluid, the actuator element E, more precisely: the active membrane layer ES, is supplied with voltage via the voltage lines 17, 18 and thus controlled to carry out the actuating movement R, for which a suitably configured control unit can be provided. A voltage-induced expansion of the active membrane layer ES causes a deflection of the membrane unit 10 along a direction X1 under the action of the spring element 21. A reduction in the applied voltage causes a contraction of the active membrane layer ES, whereby the membrane unit 10 is deflected along a direction X2 counter to the action of the spring element 21.

[0036] Compared to the balancing chamber system 106 known from the prior art according to DE 10 2017 125 962 A1 (see above), the pumps P1, P2 for filling the balancing chamber unit 7 on the fresh and used flow side and thus for conveying the dialysis fluid can be dispensed with. Instead, the conveyance takes place by means of the actuator element E, which in the exemplary embodiment according to the Figs. 3 and 4 is integrated into the membrane unit 10. This leads to a significant simplification of the structural design.

[0037] In the exemplary embodiment according to the Figs. 3 and 4 The actuator element E is also designed for capacitive detection of the deflection position of the membrane unit 10. Thus, the actuator element E also functions as a sensor element. As a result, in comparison to the

[0038] The state of the art according to DE 10 2017 125 962 A1 allows the balancing chamber system 106 to dispense with the separate inductive membrane sensors SE1, SE2 that are customary there, and a further simplified structure of the balancing chamber system 6 can be achieved. The change in the capacitance of the actuator element E results from its change in geometry during the deflection of the membrane unit 10 along the directions X1, X2, whereby the underlying physical effects are known as such. The deflection position of the membrane unit 10 detected by the actuator element E can be utilized for control and / or regulation purposes, for example, using the aforementioned control unit.

[0039] Based on the Fig. 5, 6 and 8 to 12 are differently designed balancing chamber units 7a, 7b and 7d to

[0040] 7g shown. Fig. 7shows a further exemplary embodiment of a balancing chamber unit 7c, not according to the invention. To avoid repetition, only the essential differences between the balancing chamber units 7a to 7g and the balancing chamber unit 7 according to Fig. 3 Identical components and / or sections are provided with identical reference numerals and will not be explained separately. Instead, reference will be made to the embodiment according to the Figs. 3 and 4 Differently designed components and / or sections are designated by the same reference numerals plus corresponding lowercase letters.

[0041] The balancing chamber unit 7a according to Fig. 5 differs essentially from the balance chamber unit 7 in that the membrane unit 10a has a first membrane 23a and a second membrane 24a. In contrast, the membrane unit 10 according to the Figs. 3 and 4only a single unspecified membrane, which consists of the Fig. 4 visible membrane layers and whose front side delimits the second balance chamber 9 and whose opposite rear side delimits the first balance chamber 8.

[0042] Instead, the balancing chamber unit 7a is Fig. 5 It is provided that the first membrane 23a delimits the first balancing chamber 8; the second membrane 24a delimits the second balancing chamber 9. For the volumetric coupling between the first balancing chamber 8 and the second balancing chamber 9, an incompressible coupling fluid 25a is enclosed in a fluid-tight manner between opposing surfaces of the first membrane 23a and the second membrane 24a. The incompressible coupling fluid 25a ensures that the second membrane 24a is deflected by the same volume upon deflection of the first membrane 23a, and vice versa.

[0043] In this case, both the first membrane 23a and the second membrane 24a engage the anchor plate 22 of the membrane unit 10a, although this is not absolutely necessary. In an embodiment not shown, separate anchor plates can be provided and each can be assigned to only one of the membranes.

[0044] For deflecting the membrane unit 10a and thus for conveying the dialysis fluid, at least one of the membranes 23a, 24a has the shape already defined by the Figs. 3 and 4 explained structure with an active membrane layer ES. In the present case, it is provided that the first membrane 23a has an active membrane layer ES (cf. Fig. 4 ). Alternatively, both membranes 23a, 24a can be provided with an active membrane layer ES.

[0045] The balancing chamber unit 7b according to Fig. 6 differs essentially from the balancing chamber unit 7a according to Fig. 5that a rigid coupling element 26b is provided for the volumetric coupling between the first membrane 23b and the second membrane 24b. The coupling element 26b is supported at one end on the first membrane 23b and the other end on the second membrane 24b and serves to transmit the respective deflection between the membranes 23b, 24b. In addition, an incompressible coupling fluid 25b is enclosed in a fluid-tight manner between opposing surfaces of the first membrane 23b and the second membrane 24b. In an embodiment not shown, this is omitted, so that only the coupling element 26b is provided for transmitting movement between the membranes 23b, 24b. In the balancing chamber unit 7b according to Fig. 6 only the first membrane 23b has an active membrane layer ES (cf. Fig. 4 ). The remaining structure of the first membrane 23b also corresponds to that shown in Fig. 4explained design. In contrast, the second membrane 24b is designed as a quasi "passive" membrane and thus does not provide for active adjustment. Instead, the second membrane 24b, for conveying the dialysis fluid, is guided via the coupling element 26b and the incompressible coupling fluid 25b to the deflection of the first membrane 23b induced by the active membrane layer ES.

[0046] The exemplary balancing chamber unit 7c according to Fig. 7differs essentially from the balancing chamber units 7, 7a, 7b in that instead of an actuator element integrated into the membrane unit 10c, an actuator element in the form of a linear actuator Ec is provided, arranged away from the membrane unit 10c. The linear actuator enables an actuating movement Rc, which in the embodiment shown is oriented parallel to a deflection of the membrane unit 10c. The linear actuator Ec is formed from a dielectric elastomer material M in fundamental agreement with the actuator element E of the balancing chamber units 7, 7a, 7c and is therefore a dielectric elastomer actuator. However, there is no planar actuator integrated in the membrane unit 10c in layered form, but rather the actuator element Fig. 7 A schematically illustrated configuration is provided for this purpose. The linear actuator Ec can be designed, in particular, as a bundle actuator, which enables comparatively high actuating forces with large actuating movements.

[0047] The balancing chamber unit 7d according to Fig. 8 is largely identical to the balancing chamber unit 7a according to Fig. 5 In contrast to the membrane unit 10a, the membrane unit 10d does not have an integrated spring element. Instead, both the first membrane 23d and the second membrane 24d of the membrane unit 10d are provided with an active membrane layer ES ( Fig. 4 ).

[0048] The balancing chamber unit 7e according to Fig. 9 is also largely identical to the balancing chamber unit 7a according to Fig. 5 . In contrast to the membrane unit 10a of the balancing chamber unit 7a, the balancing chamber unit 10e has two spring elements 21e integrated into the first membrane 23e and the second membrane 24e instead of the externally arranged spring element 21. The spring elements 21e are each designed as a leaf spring. For better clarity, the spring elements 21e are Fig. 9 marked with dashed lines.

[0049] The balancing chamber unit 7f according to Fig. 10 comprises a membrane unit 10f with a first membrane 23f and a second membrane 24f, which are coupled to one another by means of a coupling element 26f for the purpose of transmitting movement. The coupling element 26f engages anchor plates 22f of the first membrane 23f and the second membrane 24f. In accordance with the embodiment according to Fig. 7 The actuator element is designed as a linear actuator Ef. In contrast to the linear actuator Ec of the balancing chamber unit 7c according to Fig. 7The linear actuator Ef is integrated into the unspecified housing of the balancing chamber unit 7f and is supported at one end on a support plate 27f and at the other end on the armature plate 22f of the first membrane 23f. The support plate 27f is fixed within the housing in a manner known to those skilled in the art, so that a force transmission between the housing and the linear actuator Ef is achieved. In addition, a spring element 21f is provided, which is supported at one end on the support plate 27f and at the other end on the armature plate 22f. The coupling element 26f is tubular in the present case and extends in the axial direction through an unspecified passage in the support plate 27f for connection to the armature plate 22f of the second membrane 24f.

[0050] Based on the Figs. 11 and 12 A further embodiment with a balancing chamber unit 7g is shown. This has a membrane unit 10g, the layer structure of which is shown in a schematically simplified manner with reference to Fig. 12is shown. In addition to the active adjustment capability, the membrane unit 10g allows pressure detection of the pressure prevailing in the first balancing chamber 8 and the pressure prevailing in the second balancing chamber 9.

[0051] For the active adjustment of the membrane unit 10g, two active membrane layers ES are integrated into the layer structure in the embodiment shown. The active membrane layers ES are separated from each other by a spring element 21g in the thickness direction of the membrane unit 10g. The spring element 21g is designed in the form of a leaf spring in the embodiment shown. With respect to the plane of the drawing of the Fig. 12 The two membrane layers ES are provided with electrodes 15g, 16g on the top and bottom. The electrodes 15g, 16g are electrically conductive and are applied to the elastomer material M of the active membrane layers ES in a manner known to those skilled in the art.

[0052] In the thickness direction of the membrane unit 10g, a first sensor layer S1 is integrated into the membrane unit 10g above the active membrane layers ES. A second sensor layer S2 is integrated into the membrane unit 10g below the active membrane layers ES.

[0053] The two sensor layers S1, S2 are designed to detect the respective pressure in the first balance chamber 8 and in the second balance chamber 9. The two sensor layers S1, S2 are each formed from the dielectric elastomer material M. The further layer structure of the membrane unit 10g is described below with reference to the plane of the drawing of the Fig. 12 explained, wherein the upper side of the membrane unit 10g faces the first balancing chamber 8 and the lower side of the membrane unit 10g faces the second balancing chamber 9.

[0054] The first sensor layer S1 is provided with an upper electrode 28g on its upper side. On its underside, the first membrane layer S1 is provided with a lower electrode 29g. The lower electrode 29g is electrically insulated from the upper electrode 15g of the active membrane layer ES by means of an insulation layer 1. The second sensor layer S2 is provided with a lower electrode 30g on its underside. The lower electrode 16g arranged on the underside of the active membrane layer ES simultaneously functions as an electrode for the second sensor layer S2.

[0055] A further membrane layer 20g covers the previously described membrane structure all the way around. The further membrane layer 20g is in the form of a silicone coating.

[0056] To determine the pressure in the first balancing chamber 8 and the second balancing chamber 9, the capacitive effect of the sensor layers S1, S2 is utilized. For this purpose, a constant voltage CP2 is applied between the electrodes 16g and 30g of the second sensor layer S2. Furthermore, a constant voltage CP1 is applied between the electrodes 28g and 29g of the first sensor layer S1.

[0057] The charge of the Fig. 12visible capacitor is calculated as Q=CxU. If the lower sensor layer S2 is compressed by a pressure prevailing in the second balancing chamber 9, the capacitance C changes and thus also the charge Q. From the changed charge Q, a current change can be measured via I=dQ / dt, which is proportional to the prevailing pressure. Since the movement of the membrane unit 10g is known via capacitive detection of the deflection position by means of the active membrane layers ES, this can be taken into account accordingly. This means that during signal processing to determine the pressure, a signal component resulting from the movement of the membrane unit 10g can be subtracted, so that only a signal component equivalent to the pressure remains.

[0058] The two sensor layers S1, S2 do not necessarily have to cover the entire surface of the membrane unit 10g. Rather, it is sufficient if the first sensor layer S1 and / or the second sensor layer S2 are arranged as a strip, cross, or the like. Depending on the width of the strip or cross, the larger the capacitive area is, so that the previously described pressure determination can be carried out with comparatively higher accuracy.

[0059] It is understood that the individual features of the balancing chamber units 7, 7a to 7g can be combined with one another within the scope of the claims. For example, in the balancing chamber unit 7c, in accordance with the invention, instead of the structure of the membrane unit 10c shown in the drawing, a Fig. 5, 6A corresponding structure with a first membrane and a second membrane, as well as a corresponding volumetric coupling, should be provided. Furthermore, the shape of the balancing chamber units shown in the figures is to be understood as a highly simplified schematic and purely exemplary. Alternative shapes and / or geometries, e.g., square, oval, or round, are conceivable.

[0060] In the balancing chamber system 6 according to Fig. 2 The first balancing chamber unit 7 and the second balancing chamber unit 11 are identical in construction and are each designed according to the Figs. 3 and 4 Alternatively, a design according to the Fig. 5 to 12 be provided.

[0061] The above-described design of the first balancing chamber unit 7 - and in this case also of the second balancing chamber unit 11 - allows a significant simplification of the balancing chamber system 6 compared to the balancing chamber system 106 known from the prior art according to Fig. 1This is because, instead of the magnetically switchable valves V1 to V8 required there, the balancing chamber system provides 6 simple check valves T1 to T8. The check valves T1 to T8 can be designed, in particular, as poppet valves. The check valves T1 to T8 do not require any separate control. Rather, the check valves T1 to T8 are self-actuated. This means that the check valves T1 to T8 open and close automatically depending on the flow conditions prevailing during the delivery of the dialysis fluid. The check valves T1 to T8 are installed on the inlet and outlet sides of the respective balancing chamber with opposite opening and closing directions. The respective opening direction is determined using the Fig. 2in the immediate vicinity of the respective check valve T1 to T8. It is understood that the first balancing chamber unit 7 and the second balancing chamber unit 11 can also be used in a balancing chamber system with magnetically switchable switching valves. The same applies to the Fig. 5 to 12 shown configurations. In this respect, the check valves T1 to T8 described here are not absolutely necessary, but are particularly advantageous.

[0062] The function of the balancing chamber system 6 is essentially divided into two phases, namely a first phase and a second phase.

[0063] In the first phase, the following starting conditions exist: First balancing chamber 8 is empty, second balancing chamber 9 is full, membrane unit 10 assumes a deflection position deflected to the left, third balancing chamber 12 is full, fourth balancing chamber 13 is empty, membrane unit 14 assumes a deflection position deflected to the right, and check valves T1 to T8 are closed. From this point, membrane units 10, 14 are actively deflected under the control of their respective actuator element and its actuating movement—and not externally induced as in balancing chamber system 106. The deflection occurs synchronously in the opposite direction with capacitive detection of the deflection position by the respective actuator element.Accordingly, the membrane unit 10 of the first balancing chamber 7 is actively deflected to the right; the membrane unit 14 of the second balancing chamber unit 11 is actively deflected to the left in a manner coordinated with the deflection of the membrane unit 10. A control device configured for this purpose can be provided to control the actuator elements accordingly. Due to the above-described deflection of the membrane units 10, 14, the first balancing chamber 8 is filled with fresh dialysis fluid through the check valve T3, which opens automatically in this case. As a result, used dialysis fluid located in the second balancing chamber 9 is conveyed into the drain A through the check valve T2, which opens automatically in this case.The check valves T1 and T4 remain closed, preventing improper outflow of fresh dialysis fluid from the first balancing chamber 8 and of used dialysis fluid from the second balancing chamber 9. At the same time, due to the synchronous, opposite deflection of the membrane unit 11, used dialysis fluid is pumped through the check valve T6 into the fourth balancing chamber 13, and fresh dialysis fluid is pumped through the check valve T7 from the third balancing chamber 12 toward the dialyzer 2. The check valves T5 and T8 remain closed. This is followed by the second phase.This begins when the respective end position of the deflection of the membrane units 10, 14 is reached and, in this case, under the following starting conditions: first balancing chamber 8 full, second balancing chamber 9 empty, third balancing chamber 12 empty, fourth balancing chamber 13 full, with the membrane unit 10 being deflected to the right and the membrane unit 14 synchronously and oppositely to the left. Starting from these starting conditions, the membrane units 10, 14 are again deflected synchronously and in opposite directions, with the corresponding control of the respective actuator element.

[0064] Furthermore, an ultrafiltration pump P3 is provided and installed in one of the Fig. 1 arranged accordingly.

Claims

1. Balance chamber system (6) for a dialysis device (1) having a dialyser (2) for extracorporeal blood treatment, comprising at least one balance chamber unit (7, 7a to 7g) that is provided for fluid-conducting connection to the dialyser (2) and comprises a first balance chamber (8), which is provided for receiving and dispensing fresh-flow-side dialysis fluid, and a second balance chamber (9), which is provided for receiving and dispensing used-flow-side dialysis fluid, wherein the first balance chamber (8) and the second balance chamber (9) are fluid-tightly separated from one another and volumetrically coupled to one another by means of a membrane unit (10, 10a to 10g) that is deflectable between different deflection positions, wherein at least one actuator element (E, Ec, Ef) formed from a dielectric elastomer material (M) is provided and, under the influence of a voltage, performs an actuating movement for deflecting the membrane unit (10, 10a to 10g) and hence for conveying the fresh-flow-side dialysis fluid and the used-flow-side dialysis fluid, characterized in that the membrane unit (10a, 10b, 10d, 10e, 10f) comprises a first membrane (23a, 23b, 23d, 23e, 23f) that delimits the first balance chamber (8) and a second membrane (24a, 24b, 24d, 24e, 24f) that delimits the second balance chamber (9), wherein the first membrane (23a, 23b, 23d, 23e, 23f) and the second membrane (24a, 24b, 24d, 24e, 24f) are operatively connected to one another by means of a rigid coupling element (26b, 26f) and / or an incompressible coupling fluid (25a, 25b) for volumetric coupling of the first balance chamber (8) with the second balance chamber (9).

2. Balance chamber system (6) according to Claim 1, characterized in that the at least one actuator element (E, Ec, Ef) is configured for capacitive detection of the deflection position of the membrane unit (10, 10a to 10g) and thus additionally acts as sensor element.

3. Balance chamber system (6) according to Claim 1 or 2, characterized in that at least one spring element (21, 21e, 21f, 21g) is operatively connected to the membrane unit (10, 10a, 10b, 10c, 10e, 10f, 10g) and the actuator element (E, Ec, Ef), wherein the membrane unit (10, 10a, 10b, 10c, 10e, 10f, 10g) - when voltage is applied to the actuator element (E, Ec, Ef) - is deflected in a first direction (X1) by means of the spring element (21, 21e, 21f, 21g), and wherein the membrane unit (10, 10a, 10b, 10c, 10e, 10f, 10g) - in the event of reduced voltage - is deflected against the action of the spring element (21, 21e, 21f, 21g) in a second direction (X2), opposite to the first direction (X1), by means of the actuator element (E, Ec, Ef).

4. Balance chamber system (6) according to any of the preceding claims, characterized in that a single actuator element (E, Ef) is provided, the actuating movement of which is transmitted by means of the coupling element (26b, 26f) and / or the coupling fluid (25b) between the first membrane (23b, 23f) and the second membrane (24b, 24f).

5. Balance chamber system (6) according to any of the preceding claims, characterized in that the at least one actuator element (E) in the form of at least one active membrane layer (ES) is integrated into the membrane unit (10, 10a, 10b, 10d, 10e, 10g), in particular into the first membrane (23a, 23b, 23d, 23e, 23g) and / or the second membrane (24a, 24b, 24d, 24e, 24g).

6. Balance chamber system (6) according to Claim 5, characterized in that the active membrane layer (ES) is protected against wetting by the dialysis fluid by means of at least one further membrane layer (19, 20, 20g) and / or a coating.

7. Balance chamber system (6) according to Claim 5 or 6, characterized in that at least one sensor layer (S1, S2) formed from a dielectric elastomer material (M) is integrated into the membrane unit (10g), wherein the at least one sensor layer (S1, S2) is configured for detecting a prevailing pressure in the first balance chamber (8) and / or the second balance chamber (9).

8. Balance chamber system (6) according to any of Claims 1 to 4, characterized in that the at least one actuator element in the form of a linear actuator (Ec, Ef) with a translational actuating movement (Rc) is arranged away from the membrane unit (10c, 10f).

9. Balance chamber system (6) according to any of the preceding claims, characterized in that the balance chambers (8, 9) each have an inlet and an outlet, wherein a respective check valve (T1) to (T8) is provided for flow control through the respective inlet or outlet.

10. Dialysis device (1) having a dialyser (2) for extracorporeal blood treatment, wherein a balance chamber system (6) according to any of the preceding claims is fluid-conductively connected to a dialysis fluid chamber (4) of the dialyser (2).