IMPLANTABLE PUMPING DEVICE FOR PUMPING BODY FLUID

Description

[0001] The invention relates to an implantable pump device according to the preamble of claim 1.

[0002] Such an implantable pump device is known from DE 32 34 572 A1.

[0003] Furthermore, US patent 5,437,627 A discloses an implantable valve device for the controlled drainage of body fluid.

[0004] Another implantable pump device is known, for example, from US 9,731,101 B2. This known implantable pump device is designed to pump cerebrospinal fluid (CSF) from the ventricles of the brain into another body cavity suitable for receiving the fluid. For this purpose, the known implantable pump device is implanted, for example, into the peritoneum and / or atrium and connected to the ventricles on the inlet side and to the aforementioned cavity on the outlet side by means of suitable catheters. The known implantable pump device operates on the positive displacement principle and can be designed, in particular, as a peristaltic pump, screw pump, diaphragm pump, or piston pump. Piston pumps typically have a movable piston, a wall, and a pumping volume enclosed between the piston base and the wall.The piston moves linearly relative to the cylinder wall. This stroke of the piston is known to cause a change in the pumped volume, which results in pumping between the inlet and outlet. In conventional piston pumps, the cylinder wall is shaped like a cylinder. During the stroke, the piston slides with friction inside the cylinder, more precisely, along its inner wall. Piston sealing rings, which slide against the inner cylinder wall, are typically used to seal the piston against the inner cylinder wall.

[0005] The object of the invention is to provide an implantable pump device of the type mentioned above, which offers advantages over the prior art.

[0006] This problem is solved by providing an implantable pump device with the features of claim 1. The solution according to the invention achieves a simple design and particularly robust function. Consequently, the service life of the implantable pump device can be increased and its failure risk reduced. This leads to improved patient safety. Moreover, the simple design allows for cost-reduced manufacturing and simplified assembly. The aforementioned advantages are achieved through the inventive design of the piston and its interaction with the wall. The inventive design of the piston comprises, on the one hand, the dimensionally stable disc section and, on the other hand, the elastic ring collar section. The disc section primarily functions as a displacement element of the implantable pump device, which operates according to the displacement principle.The disc section is dimensionally stable, particularly for this purpose. This dimensional stability allows the transmission of the forces necessary for pumping the body fluid. The annular collar section primarily serves as a fluid-tight seal and provides stroke-moving support for the disc section against the wall. The annular collar section thus performs a particularly advantageous multiple function. This contributes significantly to the simplified design and robust function of the implantable pump device. To support the disc section against the wall, the annular collar section is rigidly connected to both the disc section and the wall. To allow the necessary stroke movement of the piston despite these rigid connections, the annular collar section is elastically designed. Consequently, the annular collar section deforms elastically during the piston's stroke.Due to the rigid connection of the annular collar section at its inner and outer circumferences, no relative movement occurs at these points with respect to the disc section or the wall. This eliminates frictional losses. To seal the variable pump volume enclosed between the underside of the disc section and the wall, the aforementioned rigid connection between the inner circumference of the annular collar section and the outer circumference of the disc section, and between the outer circumference of the annular collar section and the wall, is also fluid-tight. This eliminates the need for separate sealing elements. The rigid and fluid-tight connections can each be formed as a material-bonded, form-fit, and / or force-fit connection, or by means of a single-piece manufacturing process.The dimensionally stable properties of the disc section and the elastic and / or conformable properties of the annular collar section are each achieved through appropriate dimensioning of the wall thicknesses and / or material selection. Preferably, the disc section has thicker walls than the annular collar section. Preferably, the annular collar section has thinner walls than the disc section. Preferably, the difference between the wall thicknesses is at least one order of magnitude, more preferably at least two orders of magnitude. Furthermore, preferably, the radial extent between the inner and outer circumference of the annular collar section is at least three times, more preferably at least five times, more preferably at least ten times, the wall thickness of the annular collar section. In a preferred embodiment, the radial extent of the annular collar section is 2 mm to 6 mm, more preferably 3 mm.In a preferred embodiment, the disc section has a diameter of 14 mm to 20 mm, particularly preferably 16 mm. The fluid path of the implantable pump device has an inlet at one end and an outlet at the other. The pump volume forms a section of the fluid path and is arranged between the inlet and the outlet in the direction of flow of body fluid. The inlet and the outlet are fluidically connected to each other via the pump volume. In one embodiment, control elements for controlling the pump delivery are arranged in the fluid path, preferably designed as check valves. In another embodiment, the implantable pump device does not have such control elements.Instead, corresponding control elements are located, for example, upstream of the inlet and / or downstream of the outlet of the implantable pump device, preferably in a fluid line system or the like that can be connected to the implantable pump device. In one embodiment, the implantable pump device has an actuator operatively connected to the piston for driving the stroke movement. The actuator is preferably operatively connected to the piston, in particular the disc element, in a force- and / or motion-transmitting manner. The operative connection can be mechanical and / or fluidic. A magnetic operative connection is also conceivable in principle. In a further embodiment, the implantable pump device does not have such an actuator, whereby the actuator can instead be connected to the implantable pump device, for example, as part of a separate drive device.

[0007] The implantable pump device according to the invention is particularly advantageous for pumping body fluids, especially cerebrospinal fluid. Naturally, the solution according to the invention is equally suitable for pumping medical fluids.

[0008] In this embodiment of the invention, the disc section and the annular collar section are formed integrally as a single unit. Due to this integral construction, the annular collar section is rigidly and fluid-tightly connected to the outer circumference of the disc section at its inner circumference, and vice versa. Consequently, a separate joining connection is unnecessary. This results in a further simplified design and improved robustness. In this embodiment of the invention, the piston can be manufactured, for example, as a turned part, a casting, or a formed part. Alternatively, additive manufacturing is conceivable.

[0009] In a further embodiment of the invention, the disc section and the annular collar section are each made of metal, preferably titanium. The inventors have recognized that this offers particular advantages. Firstly, manufacturing from metal, preferably titanium, results in biocompatible properties. Secondly, it offers manufacturing advantages. This applies to both multi-part and one-piece manufacturing of the disc and annular collar sections. Preferably, the wall is also made of metal, preferably titanium. In combination with the metallic manufacturing of the annular collar section, this offers particular manufacturing advantages. For example, the connection between the outer circumference of the annular collar section and the wall can be reliably and fluid-tightly formed using simple means.

[0010] In a further embodiment of the invention, the outer circumference of the annular collar section is firmly and fluid-tightly joined to the wall by means of a material-bonded connection. In one embodiment, the material-bonded connection is an adhesive bond. In another embodiment, a welded connection is provided. This embodiment of the invention results in further manufacturing advantages. Moreover, the construction of the implantable pump device is further simplified, since separate connecting elements for joining the outer circumference of the annular collar section to the wall can be dispensed with.

[0011] In a further embodiment of the invention, the material-bonded joint is a weld, preferably produced without a welding filler. In this case, the ring collar section and the wall are preferably each made of metal or weldable plastic. Compared to, for example, an adhesive bond, the weld offers improved biocompatible properties. This is particularly true when the weld is produced without a welding filler. In this case, the weld is, for example, a laser weld, a friction weld, or a resistance weld.

[0012] Furthermore, according to the invention, the wall thickness and / or shape of the ring collar section is designed such that a stroke-induced elastic deformation of the ring collar section produces a spring force opposing the stroke movement, whereby the spring force causes or at least assists in the complete return of the piston. Thus, in this embodiment, the ring collar section additionally functions as a kind of spring element for returning the piston. This eliminates the need for separate components for returning the piston. At the very least, such components can be dimensioned less robustly. In other words, in this embodiment, the ring collar section preferably functions as a kind of disc spring.

[0013] In a further embodiment of the invention, the ring collar section has a planar shape. Consequently, the ring collar section extends in a planar direction in the radial and / or circumferential direction. Such a planar design facilitates simple manufacturing. Furthermore, the planar shape simplifies the creation of a tight and fluid-tight connection between the outer circumference of the ring collar section and the wall.

[0014] In a further embodiment of the invention, the ring collar section has a corrugated shape. The corrugation is formed in the radial direction and / or in the circumferential direction of the ring collar section. Preferably, the ring collar section has several radial corrugations. In other words, the ring collar section is provided with several corrugations along its radial extent, which extend continuously in the circumferential direction. The inventors have recognized that the corrugated shape particularly supports the required elastic deformation of the ring collar section. This facilitates a smooth yet sufficiently supported and / or guided up-and-down movement of the disc section connected to the ring collar section.

[0015] In a further embodiment of the invention, the wall has an additional elastic annular collar section, the outer circumference of which is rigidly and fluid-tightly connected to the outer circumference of the elastic annular collar section of the piston. This additional annular collar section improves the deformation behavior of the piston's annular collar section. The improved deformation behavior results in particularly smooth stroke movement of the disc section. This supports particularly energy-efficient operation of the implantable pump device. Preferably, the additional annular collar section projects radially outwards from a central section of the wall opposite the disc section. In this embodiment of the invention, the pump volume is preferably enclosed between the underside of the disc section and the aforementioned central section.The annular collar section of the disc element and the further annular collar section of the wall rest against each other at their outer circumferences and are firmly and fluid-tightly connected there. A material-locking, form-locking, and / or force-locking connection is suitable for this purpose. A welded connection is preferred.

[0016] In a further embodiment of the invention, the annular collar section of the piston and the further annular collar section of the wall are arranged and / or designed in a mirror-symmetrical manner with respect to a radial central longitudinal plane of the pump volume. This mirror symmetry can offer advantages in manufacturing. Furthermore, it results in a particularly advantageous elastic deformation behavior of the two annular collar sections and thus a stroke flexibility of the disc section that meets specific requirements.

[0017] In a further embodiment of the invention, the fluid path includes a first check valve, which is arranged between the inlet and the pump volume, and a second check valve, which is arranged between the pump volume and the outlet and opens and closes in the opposite direction to the first check valve. The first check valve can also be referred to as the inlet valve. The second check valve can also be referred to as the outlet valve. Due to their design, the two check valves enable a particularly simple construction of the implantable pump device. Furthermore, they allow for a particularly robust and therefore interference-resistant control of the pumping of the body fluid. In a further embodiment, electronic control valves or the like are provided instead of check valves.

[0018] In a further embodiment of the invention, the first and / or the second check valve are integrated into the wall. This results in several design advantages. Firstly, compared to integration into the piston, which is generally conceivable, a reduction in oscillating mass can be achieved. Secondly, available installation space can be used more efficiently. This enables a particularly compact design of the implantable pump device.

[0019] In a further embodiment of the invention, a section of the fluid path extending between the inlet and the pump volume borders a piston rear face, which is located opposite the piston base along the stroke axis. This pressurizes the piston rear face with the inlet-side pressure of the body fluid. This enables compensation of pressure fluctuations with surprisingly simple means. In prior art solutions, the piston rear face is encapsulated from the prevailing ambient pressure in the usual manner. Consequently, fluctuations in ambient pressure affect only the piston base via the patient's body fluid. In implantable pump devices known in the prior art, this can lead to an increased force requirement for the piston's stroke movement.This results in increased energy consumption, which is disadvantageous for various reasons. In the solution according to the invention, the inlet-side pressure of the body fluid—and thus indirectly the ambient pressure—acts on the rear of the piston. Consequently, only the differential pressure prevailing between the pump volume and the outlet needs to be overcome to pump the body fluid. This leads to a relatively smooth stroke movement and enables particularly energy-efficient operation of the implantable pump device. If the implantable pump device is designed according to one of the preceding embodiments, the rear of the piston is the upper surface of the dimensionally stable disc section opposite the underside along the stroke axis. The section of the fluid path adjacent to the rear of the piston and / or the upper surface of the disc section can also be referred to as a compensation chamber.During operation of the implantable pump device, body fluid flows from the inlet through the compensation chamber, from there into the pump volume, and is then pumped from there towards the outlet. In other words, the compensation chamber is constantly filled with body fluid during operation of the implantable pump device. This prevents stagnant fluid and the associated disadvantages. In particular, it counteracts agglomeration on the back of the piston and the resulting bacterial growth or other harmful phenomena.

[0020] In a further embodiment of the invention, the implantable pump device comprises a housing with a first interior space in which the piston, the wall, and the fluid path are arranged, and a second interior space which is fluid-tightly sealed against the environment and the first interior space and is designed to accommodate further components of the pump device. These further components may, for example, be an actuator for driving the piston's stroke and / or a control device for controlling the actuator.

[0021] The invention further relates to an implantable device with a pump device according to one of the preceding claims. In one embodiment, the implantable device is a dialysis device for use in cerebral microdialysis, wherein the pump device is configured for pumping cerebrospinal fluid. In another embodiment, the implantable device serves for pain therapy and / or the treatment of spasticity.

[0022] Further features and advantages of the invention will become apparent 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 highly simplified schematic sectional view of an embodiment of an implantable device according to the invention, which is provided with an embodiment of an implantable pump device according to the invention, Fig. 2 the implantable pump device according to Fig. 1 In a perspective, sectioned exploded view, Fig. 3, a piston, a wall and a pump volume enclosed between these components of the implantable pump device according to the Fig. 1 and 2 , Fig. 4 a variant of the arrangement according to Fig. 3 and Fig. 5 another variant of the arrangement according to Fig. 3 .

[0023] According to Fig. 1 is a pump device 1 that can be implanted into the body of a patient for pumping a body fluid.

[0024] At the in Fig. 1 In the embodiment shown, the implantable pump device 1 is a component of a schematically simplified implantable device 100. The implantable device 100 is intended for use in cerebral microdialysis. In this respect, the implantable pump device 1 serves to pump cerebrospinal fluid. Alternatively, the implantable device 100 can be used, for example, in pain therapy and / or for the treatment of spasticity.

[0025] The implantable pump device 1 (hereinafter abbreviated: pump device) has a piston 2 movable along a stroke axis H with a piston base 3, a wall 4 opposite the piston base 3 along the stroke axis H and a pump volume V enclosed between the piston base 3 and the wall 4 (see also Fig. 3 The pump volume V forms a section of a fluid path F extending between an inlet E and an outlet A of the pumping device 1. A linear stroke of the piston 2 along the stroke axis H causes a change in the pump volume V and consequently a pumping of the body fluid between the inlet E and the outlet A. In a case of - with respect to the plane of the drawing of the Fig. 1 - During the downward movement of piston 2, the pump volume V decreases. During the upward movement of piston 2, the pump volume V increases. This upward movement causes body fluid to be drawn into the pump volume V. This downward movement causes body fluid to be expelled from the pump volume V.

[0026] To control the pumping process described above along the liquid path F, the pumping device 1 in the illustrated embodiment has control elements which are described in more detail below.

[0027] The piston 2 has a dimensionally stable disk section 5 and an elastic annular collar section 6. A lower surface 7 of the disk section 5, facing the wall 4 along the stroke axis H, forms the piston base 3. The elastic annular collar section 6 projects outwards from the disk section 5 in the radial direction R. The annular collar section 6 is continuous around the disk section 5 in the circumferential direction. The annular collar section 6 has an inner circumference 8 and an outer circumference 10. The inner circumference 8 can also be referred to as the inner ring edge or inner ring rim. The outer circumference 10 can also be referred to as the outer ring rim or outer ring rim. The inner circumference 8 is rigidly and fluid-tightly connected to an outer circumference 9 of the disk section 5. The outer circumference 9 of the disk section 5 can also be referred to as the outer disk rim or outer disk rim.The outer circumference 10 of the annular collar section 6 is rigidly and fluid-tightly connected to the wall 4. This means that the dimensionally stable disc section 5 is supported relative to the wall 4 in two ways: firstly, along the stroke axis H, it is linearly movable (indirectly) along the wall 4 by means of the elastic annular collar section 6; and secondly, the dimensionally stable disc section 5 is fluid-tightly connected to the wall 4 (indirectly) by means of the annular collar section 6.

[0028] In the present case, a radial extent between the inner circumference 8 and the outer circumference 10 of the ring collar section 6 is clearly greater, namely by at least one order of magnitude, than an axial extent and / or wall thickness of the ring collar section 6. In embodiments not shown in the figures, the radial extent is at least 3 times greater than the wall thickness.

[0029] During the pumping of body fluid, the dimensionally stable disc section 5 moves linearly up and down along the stroke axis H. Due to its dimensionally stable design, the disc section 5 experiences no, or at least no significant, elastic deformation. This ensures, in particular, that the pumping forces necessary for conveying the body fluid can be introduced into the disc section 5 as required and transferred from it to the pumping volume V. In contrast to the dimensionally stable disc section 5, the annular collar section 6 experiences elastic deformation during the stroke movement. During a downward movement of the piston 2, and thus of the disc section 5, the annular collar section 6 is elastically deformed at its inner circumference 8 along the stroke axis H in the direction of the wall 4. The outer circumference 10 remains stationary relative to the wall 4.The elastic deformability of the annular collar section 6 ensures that the disc section 5 can move linearly up and down along the stroke axis H. The fluid-tight connection on both the inner circumference 8 and the outer circumference 10 ensures a reliable fluid-tight seal between the piston 2 on the one hand and the wall 4 on the other. In other words, the annular collar section 6 functions both as a bearing and / or support element and as a sealing element.

[0030] To achieve the required elastic deformability of the ring collar section 6, it has a smaller wall thickness, which will be further specified, compared to the disc section 5 in the illustrated embodiment. In other words, the disc section 5 has a thicker wall than the ring collar section 6. Conversely, the ring collar section 6 has a thinner wall than the disc section 5.

[0031] In the illustrated embodiment, the disc section 5 has a flat circular-cylindrical shape with respect to the lifting axis H. The outer circumference 9 of the disc section 5 is therefore circular. The ring collar section 6, which projects radially outwards from the disc section 5, has an annular shape in the illustrated embodiment. Such a circular shape of the disc section 5 and the ring collar section 6 is not mandatory. In an embodiment not shown, the disc section 5 and the ring collar section 6 are instead each oval.

[0032] In the illustrated embodiment, the disc section 5 and the annular collar section 6 are formed integrally as a single unit. Consequently, the disc section 5 and the annular collar section 6 are distinct sections of one and the same component. Due to this integrally formed unit, a separate material-, force-, and / or form-fit connection between the inner circumference 8 of the annular collar section 6 and the outer circumference 9 of the disc section 5 is unnecessary. This simplifies the design and manufacturing process. Furthermore, the required mechanical and fluid-tight connection between the inner circumference 8 and the outer circumference 9 can be designed to be particularly robust and reliable.

[0033] The aforementioned one-piece design is particularly advantageous, but not essential for implementing the present invention. Accordingly, in an embodiment not shown in the figures, a multi-part manufacturing of the piston is provided, wherein the disc section and the ring collar section are manufactured as separate components and then joined together at the inner and outer circumferences by means of a suitable joining connection in a tight and fluid-tight manner.

[0034] In the illustrated embodiment, the disc section and the ring collar section are made of metal. Specifically, they are made of titanium. Manufacturing them from metal, and especially titanium, ensures the required biocompatibility.

[0035] In an embodiment not shown in the figures, a biocompatible plastic is used instead of metal to manufacture the disc section, the ring collar section, and / or the piston. Biocompatible plastics are known to those skilled in the art.

[0036] In the illustrated embodiment, the outer circumference 10 of the ring collar section 6 is firmly and fluid-tightly joined to the wall 4 by means of a material-bonded connection 11. The material-bonded connection 11 is designed differently in different embodiments. In the illustrated embodiment, the material-bonded connection 11 is a welded joint S.

[0037] Depending on the prevailing material choice, the welded joint S can be a metal or a plastic welded joint for the piston 2 and the wall 4.

[0038] In the embodiment shown, the wall 4 is also made of metal, specifically titanium. The welded joint S is accordingly a metal welded joint.

[0039] In the illustrated embodiment, the weld joint S is produced without the use of a welding filler. This offers further advantages. Suitable welding processes for forming the weld joint S include, for example, laser welding, friction welding, and / or resistance welding.

[0040] Further with reference to Fig. 3 The wall thickness T and / or the shape G of the annular collar section 6 is designed such that a stroke-induced elastic deformation of the annular collar section 6 generates a spring force C that opposes the stroke movement, whereby the spring force C causes or at least assists in the complete return of the piston. During a downward movement of the piston 2, the annular collar section 6 is elastically prestressed. The elastic prestress of the annular collar section 6 causes the aforementioned spring force C. This spring force acts in the opposite direction to the downward movement of the piston 2. In other words, the elastically deformed annular collar section 6 pushes the dimensionally stable disk section 5 back into its initial position along the stroke axis H. Depending on the dimension of the wall thickness T and the specific shape G, the return is either caused exclusively by the elastic deformation or the spring force C, or at least assisted by both.In the present case the latter is provided, wherein an (additional) spring element 12 is present for resetting the piston and is operatively connected to the piston 2 in a manner described in more detail (see . Fig. 1 ).

[0041] In the embodiment shown, the wall thickness T is 0.07 mm. In embodiments not shown in the figures, the wall thickness is between 0.04 mm and 0.15 mm.

[0042] The collar section 6 extends radially from its inner circumference 8 towards its outer circumference 10. This radial extension is 3 mm in this case. In embodiments not shown in the figures, the radial extension is between 2 mm and 6 mm.

[0043] The ring collar section 6 is, in this case, at least substantially radially extended.

[0044] In the illustrated embodiment, the ring collar section 6 has an axial inclination, i.e., the inner circumference 8 and the outer circumference 10 are spaced apart from each other by an axial distance. This axial distance is 0.3 mm in the illustrated embodiment. In embodiments not shown in the figures, the axial distance is between 0.1 mm and 0.5 mm.

[0045] In the illustrated embodiment, the wall thickness of the dimensionally stable disc section is 1.5 mm (not specified in detail). In embodiments not shown in the figures, the wall thickness of the disc section is between 1.0 mm and 5.0 mm. Furthermore, the disc section 5 has a diameter of 16 mm in this embodiment. In embodiments not shown in the figures, the diameter is between 14 mm and 20 mm.

[0046] In the present case, the elastic ring collar section 6 has an axial flange 13 positioned along the lifting axis H in the region of its outer circumference 10. The axial flange 13 simplifies the formation of the welded joint S. In addition, the axial flange 13 supports the elastic deformation behavior of the ring collar section 6.

[0047] Further with reference to Fig. 3 The shape G of the ring collar section 6 is flat in both the radial direction R and the circumferential direction. This means that there are no protrusions, indentations, waves, or the like on the ring collar section 6.

[0048] During the Fig. 1 bis 3 In the embodiment shown, the wall 4 also has an elastic annular collar section 14. This is hereinafter referred to as the further annular collar section 14. The further annular collar section 14 projects outwards in the radial direction R and has an outer circumference 15. The outer circumference 15 of the further annular collar section 14 is firmly and fluid-tightly connected to the outer circumference 10 of the elastic annular collar section 6 of the piston 2. Consequently, the aforementioned joining connection 11, more precisely: the welded connection S, is formed between the outer circumference 10 of the annular collar section 6 of the piston 2 and the outer circumference 15 of the further annular collar section 14 of the wall 4. As a result of the further elastic annular collar section 14, the wall 4 is elastically compliant in sections, namely in the area of ​​the further annular collar section 14. This supports the disk section 5 during its stroke movement along the stroke axis H by a kind of series arrangement of springs.The inventors recognized that the presence of the additional ring collar section 14 offers various advantages. In particular, it supports the required stroke mobility of the piston 2.

[0049] In the illustrated embodiment, the annular collar section 6 of the piston 2 and the further annular collar section 14 of the wall 4 are arranged and designed in a mirror-symmetrical manner with respect to a radial central longitudinal plane of the pump volume V. The wall 4 with its further annular collar section 14 can also be referred to as a further piston. This is due to the fact that the wall with its further annular collar section 14 is largely identical in design to the piston 2, with a key difference being the arrangement of the pistons, which are movable relative to the stroke axis H on the one hand and fixed relative to it on the other – apart from the further annular collar section 14. The wall 4 can therefore also be referred to as a fixed wall.

[0050] Based on the Fig. 4 und 5 are variants of the arrangement according Fig. 3 The following discussion focuses solely on the key differences between the variants. For all other aspects, please refer to what has been previously disclosed.

[0051] Based on the variant according to Fig. 4 It becomes clear that the further collar section 14 according to Fig. 3 This is not strictly necessary. Accordingly, the wall 4' there does not have such an annular collar section. Apart from this, the piston 2 is arranged Fig. 4 identical to piston 2 after Fig. 3 .

[0052] The variant according Fig. 5 differs from the variant according to by a wavy shape G' of the collar section 6' Fig. 4 The corrugated shape G' of the ring collar section 6' is accompanied by axially extending indentations 61 and protrusions 62. The indentations 61 and protrusions 62 extend continuously along the circumference of the ring collar section 6. Alternatively, it can also be said that the ring collar section 6' has waves, more precisely: radial waves. The inventors have recognized that the corrugated shape G' offers a different advantage compared to the variant according to [reference missing]. Fig. 4 Improved lifting mobility of disc section 5 is enabled.

[0053] At the in Fig. 5 In the variant shown, the axial extent of the indentations 61 and the protrusions 62 is 0.4 mm each. This axial extent can also be referred to as the wave height of the corrugated shape G'. In variants not shown in the figures, the axial extent (wave height) is between 0.2 mm and 0.8 mm. In the variant shown, the inner and outer circumferences of the ring collar section 6' are axially spaced apart by the aforementioned wave height.

[0054] As previously mentioned, the illustrated embodiment includes check valves 16 and 17 as control elements for the pump delivery. The check valves 16 and 17 are arranged in the fluid path F. Check valve 16 can also be referred to as the first check valve or inlet valve. Check valve 17 can also be referred to as the second check valve or outlet valve. The first check valve 16 is arranged between the inlet E and the pump volume V in the fluid path F. The second check valve 17 is arranged between the pump volume V and the outlet A in the fluid path F. The opening and closing directions of the two check valves 16 and 17 are opposite to each other. The first check valve 16 opens during an upward movement of the piston 2 and closes during a downward movement of the piston.The second check valve 17 opens when the piston 2 moves downwards and closes when it moves upwards.

[0055] In the illustrated embodiment, the two check valves 16, 17 are integrated into the wall 4. For this purpose, the wall 4 has a first receiving recess 18 and a second receiving recess 19. The receiving recesses 18, 19 are recessed into the wall 4 along the stroke axis H and are each designed to receive one of the check valves 16, 17. The first receiving recess 18 receives the first check valve 16. The second receiving recess 19 receives the second check valve 17.

[0056] In an embodiment not shown in the figures, at least one of the two check valves is integrated into the piston 2. In another embodiment not shown, both check valves are integrated into the piston 2.

[0057] Further with reference to Fig. 1 It is shown that in the illustrated embodiment, the fluid path F is guided section by section along a piston rear face 20 of the piston 2. In other words, the fluid path F has a section K (see Fig. 1 ), which is directly adjacent to the rear of the piston 20. Section K is located between the inlet E and the pumping volume V. In this configuration, section K is also positioned upstream of the first check valve 16 in the direction of flow. During pumping, the body fluid flows from the inlet E along the fluid path F into section K and from there via the first check valve 16 into the pumping volume V. Consequently, the rear of the piston 20 is pressurized by the inlet-side pressure p of the body fluid being pumped. In the illustrated embodiment, this pressure acts essentially on an entire surface of the rear of the piston 20, which also includes the outer surfaces of the annular collar section 6 facing section K. Due to the pressure p prevailing in section K, the piston 2 is subjected to a force along the stroke axis H in the direction of the wall 4.This force application causes pressure compensation and enables particularly energy-efficient operation of the pump device 1, which will be explained in more detail below.

[0058] In the illustrated embodiment, the pump device has a housing 21. The housing 21 is subdivided into a lower half and an upper half. This subdivision is shown schematically by reference to Fig. 2 This is illustrated by the dashed line shown. The aforementioned subdivision divides an unspecified overall interior space of the housing 21 into a first interior space 22 and a second interior space 23. The piston 2, the wall 4, and the fluid path F are arranged in the first interior space 22. The second interior space 23 is sealed fluid-tight and / or pressure-tight from the environment U and the first interior space 22. The second interior space 23 serves to accommodate further components of the pumping device 1. For example, an actuator for driving the pumping movement of the piston 2 can be arranged in the second interior space 23. Alternatively or additionally, control electronics for controlling the actuator and / or the stroke movement can be arranged in the second interior space 23. Details in this regard are not essential for the implementation of the present invention, so further descriptions are omitted.

[0059] In the illustrated embodiment, a partition 24 is provided to seal the second interior space 23 against the environment U and the first interior space 22 in a fluid- and / or pressure-tight manner. The partition 24 subdivides the entire interior space of the housing 21 into the aforementioned lower and upper halves, or the first and second interior spaces 22, 23. In this embodiment, the partition 24 has a circular disk shape with a central opening 25. The opening 25 serves for the axial passage of a pin 28, which projects axially upwards from the rear of the piston 20, i.e., towards the second interior space 23. In the illustrated embodiment, the pin 28 is integrally connected to the other sections of the piston 2. The pin 28 is configured for force- and motion-transmitting operative connection with an actuator. In other words, the pin 28 serves to introduce pumping forces into the piston 2.The aforementioned pumping forces are generated, for example, by the actuator located within the second interior space 23. The pin 28 extends axially through the opening 25 and is sealed by means of a sealing disc 26. In the illustrated embodiment, the sealing disc 26 is made of metal, specifically titanium. The sealing disc 26 exhibits membrane-elastic properties and can therefore also be referred to as a sealing diaphragm.

[0060] In the based on Fig. 1 In the assembly state shown, the pin 28 is axially fitted into an unspecified receiving bore of a pressure piece 27. The pressure piece 27 serves to apply the aforementioned pumping forces and is supported on its underside, against the downward movement of the piston 2, by the spring element 12 on an unspecified upper surface of the partition wall 24. The spring element 12 is, in this case, indirectly supported on the partition wall, namely via the sealing disc 26.

[0061] Based on Fig. 1 It becomes clear that the entire fluid path F extends away from and separate from the second interior space 23. Due to the fluid- and / or pressure-tight encapsulation of the second interior space 23, it is not essential that the components located there be biocompatible. Conversely, the components and / or sections adjacent to the fluid path F can be made biocompatible relatively easily. In the embodiment shown, the entire fluid path F, or rather all components and / or sections adjacent to the fluid path F, are biocompatible. This biocompatibility is ensured here by a suitable material selection for the piston and the wall, as well as the check valves.

[0062] To ensure that the piston rear 20 is also in an upper end position of the piston 2 - as shown by Fig. 1As shown, when the piston is pressurized with the inlet-side fluid pressure p, it has two spacer sections 29. In the upper end position, the spacer sections 29 rest against the partition 24, more precisely: against its underside. The spacer sections 29 ensure that the rear of the piston 20 does not directly contact the partition 24 and that section K remains open to allow pressure transmission to the rear of the piston 20.

[0063] In the illustrated embodiment, the downward movement of piston 2 causes body fluid to be expelled from the pump volume V through outlet A and simultaneously draws body fluid in through inlet E up to section K. During the upward movement of piston 2, the body fluid initially pumped up to section K is drawn further into the pump volume V.

[0064] The previously explained pressure compensation is advantageous, for example, when the patient's ambient pressure (atmospheric pressure) changes. Such a change in ambient pressure naturally also affects the pressure of the body fluids. Their pressure corresponds to the ambient pressure. In some situations, considerable pressure changes can occur, for example, during air travel. In an aircraft cabin, the pressure can be up to 40,000 Nm⁻² (equivalent to 40,000 Pa or 400 mbar) lower than on the ground. This lower pressure is therefore present on the inlet and outlet sides of the pump device and thus also within the pump volume V. However, the pressure of the interior space 23 remains constant because it is sealed off from the outside. Consequently, a pressure difference arises.

[0065] The pressure differential acting on the entire movable piston 2 would result in a force that would make it difficult for the piston 2 to return to its initial position. To counteract this, increased restoring forces can be provided by adjusting the spring constant of the piston 2 and / or the spring element 12. However, increased restoring forces in this way are disadvantageous under typical ambient pressure conditions. This is because correspondingly higher pumping forces would then have to be applied, which would lead to greater energy consumption.

[0066] Forces arising from prevailing pressure differences are reduced in particular by the use of the partition 24, which divides the interior of the housing 21 into a pressure-constant area 23 and a pressure-adapted area 22. The resulting force from said pressure difference now acts primarily on the surface of the sealing disc 26 and not on the entire piston 2. The required pumping forces are therefore much less dependent on the ambient pressure, since this pressure is applied to both sides of the piston 2.

Claims

1. An implantable pump device (1) for pumping a body fluid, having: a piston (2, 2') which is reciprocatingly movable along a stroke axis (H) with a piston head (3), a wall (4, 4') lying opposite the piston head (3) along the stroke axis (H), and having a pump volume (V) which is enclosed between the piston head (3) and the wall (4, 4') and forms a portion of a fluid path (F) extending between an inlet (E) and an outlet (A), wherein a stroke movement of the piston (2, 2') causes a change in pump volume (V) and accordingly a pump delivery of body fluid between the inlet (E) and the outlet (A), wherein the piston (2, 2') has a form-stable disc portion (5), the underside (7) of which forms the piston head (3), and an elastic ring collar portion (6, 6'), wherein the underside (7) faces the wall (4, 4') along the stroke axis (H), wherein the elastic ring collar portion (6, 6') protrudes radially from the disc portion (5), at its inner periphery (8) is fixedly and fluid-tightly connected to an outer periphery (9) of the disc portion (5), and at its outer periphery (10) is fixedly and fluid-tightly connected to the wall (4), whereby the form-stable disc portion (5) rests via the elastic ring collar portion (6, 6') on the wall (4, 4') so as to be reciprocatingly movable relative thereto and is fluid-tightly connected thereto, characterized in that a thickness (T) and / or a shaping (G, G') of the ring collar portion (6, 6') causes a spring force (C) opposite the stroke movement, wherein the spring force (C) causes or at least supports a complete return of the piston (2, 2').

2. The implantable pump device (1) as claimed in claim 1, wherein the disc portion (5) and the ring collar portion (6, 6') are formed integrally and cohesively with one another.

3. The implantable pump device (1) as claimed in claim 1 or 2, wherein the disc portion (5) and the ring collar portion (6, 6') are each made of metal, preferably titanium.

4. The implantable pump device (1) as claimed in any of the preceding claims, wherein the outer periphery (10) of the ring collar portion (6, 6') is joined fixedly and fluid-tightly to the wall (4, 4') by means of a substance-bonded joint connection (11).

5. The implantable pump device (1) as claimed in claim 4, wherein the substance-bonded joint connection (11) is a weld connection (S), preferably produced without a welding additive.

6. The implantable pump device (1) as claimed in any of the preceding claims, wherein the ring collar portion (6) has a flat shaping (G).

7. The implantable pump device (1) as claimed in any of claims 1 to 5, wherein the ring collar portion (6') has an undulating shaping (G').

8. The implantable pump device (1) as claimed in any of the preceding claims, wherein the wall (4) has a further elastic ring collar portion (14), the outer periphery (15) of which is fixedly and fluid-tightly connected to the outer periphery (10) of the elastic ring collar portion (6, 6') of the piston (2, 2').

9. The implantable pump device (1) as claimed in claim 8, wherein the ring collar portion (6, 6') of the piston and the further ring collar portion (14) of the wall (4) are arranged and / or configured mirror-symmetrically relative to a radial center longitudinal plane of the pump volume (V).

10. The implantable pump device (1) as claimed in any of the preceding claims, wherein the fluid path (F) has a first check valve (16) which is arranged between the inlet (E) and the pump volume (V), and a second check valve (17) which is arranged between the pump volume (V) and the outlet (A), and opens and closes in the opposite direction to the first check valve (16).

11. The implantable pump device (1) as claimed in claim 10, wherein the first check valve (16) and / or the second check valve (17) are integrated in the wall (4, 4').

12. The implantable pump device (1) as claimed in any of the preceding claims, wherein a portion (K) of the fluid path (F) extending between the inlet (E) and the pump volume (V) adjoins a piston back (20) of the piston (2, 2') which lies opposite the piston head (3) along the stroke axis (H), whereby the piston back (20) is pressurized with an inlet-side pressure (p) of the body fluid.

13. The implantable pump device (1) as claimed in claim 12, characterized by a housing (21) with a first inner chamber (22) containing the piston (2, 2'), the wall (4, 4') and the fluid path (F), and with a second inner chamber (23) which is sealed fluid-tightly against an environment (U) and the first inner chamber (22) and is configured to receive further components of the pump device (1).

14. An implantable device (100) with a pump device (1) as claimed in any of the preceding claims.