Abstract
A sealed micropump includes an integrated motor and at least one impeller for generating fluid flow inside a housing of the micropump. The impeller includes a radial sliding bearing with a spider bearing for supporting an impeller pin of the impeller inside the housing. The impeller pin includes a sheathing of a material different from a material of the spider bearing.
Claims
1-12. (canceled)
13. A cardiac support system comprising: a sealed micropump, the sealed micropump comprising: an integrated motor; and at least one impeller for generating fluid flow inside a housing of the micropump, wherein the at least one impeller comprises a radial sliding bearing comprising a spider bearing configured to support an impeller pin of the impeller inside the housing, and wherein the impeller pin comprises a sheathing comprised of a material different from a material of the spider bearing.
14. The system of claim 13, wherein the impeller pin and the spider bearing each comprise a metallic material, and wherein the sheathing of the impeller pin comprises a plastic material.
15. The system of claim 13, wherein the impeller pin and the spider bearing each comprise titanium, and wherein the sheathing of the impeller pin comprises polyetheretherketone (PEEK).
16. The system of claim 13, wherein the impeller pin tapers in a region of the sheathing.
17. The system of claim 16, wherein a radial cross-section of the sheathing of the impeller pin in a bearing region is the same as a radial cross-section of the impeller pin outside the bearing region.
18. The system of claim 13, wherein the sheathing of the impeller pin comprises a coating.
19. The system of claim 13, wherein the sheathing of the impeller pin comprises a sleeve.
20. The system of claim 13, wherein the sheathing of the impeller pin extends beyond the spider bearing.
21. The system of claim 20, wherein the sheathing comprises a cap, the cap comprising an extension extending beyond the spider bearing.
22. The system of claim 21, wherein the extension tapers.
23. The system of claim 21, wherein the extension is conical or semi-ellipsoidal.
24. The system of claim 13, wherein the sealed micropump is configured to pump blood.
25. The system of claim 13, wherein an outer diameter of the sealed micropump is at most 10 mm.
Description
[0014] The drawings show:
[0015] FIG. 1 a current development of a sealed micropump comprising an integrated motor (partial section in longitudinal section) as the starting point of the invention;
[0016] FIG. 2 a longitudinal section through a radial sliding bearing of an impeller pin of the sealed micropump of FIG. 1;
[0017] FIG. 3 a longitudinal section through a radial sliding bearing of an impeller pin of a sealed micropump in a preferred embodiment of the invention and
[0018] FIG. 4 comparative cross-sections through the radial sliding bearings of FIG. 2 (4A) and the embodiment of a sliding bearing according to the invention of FIG. 3 (4B).
[0019] FIG. 1 shows the hydraulically active part of a completely sealed micropump 10 according to a current development of such pumps in cross-section. This micropump 10 is in particular intended to be a blood pump for minimally invasive implantations (intravascular blood pump). The micropump 10 is driven by an integrated electric motor, of which the motor shaft 11 is shown here. The rotor or the impeller 19 with the impeller blades (blades) 12 is radially and axially supported via a pivot bearing 13, whereby the torque is transmitted via a permanent-magnetic coupling 14. The required blood flow is produced inside the housing 15 of the sealed blood pump 10 by means of the impeller 19. In a sense, the impeller 19 forms a propeller (impeller) enclosed by a housing. The arrow 20 indicates the magnetically acting forces. The arrow 21 indicates the hydraulically effective forces. The impeller pin 190 (bearing pin) of the impeller 19 is additionally supported via a radial sliding bearing 16 which is located upstream. The radial sliding bearing 16 comprises a spider bearing 17 with a bearing bushing 18 inserted therein and the impeller pin 190 which rotates inside the bearing bushing 18. The bearing bushing 18 is provided to avoid a frictionally unfavorable material pairing between the impeller pin 190 and the spider bearing 17, for example the titanium-titanium material pairing, which is associated with a high degree of wear. The bearing bushing 18 can be made of polyetheretherketone (PEEK), so that the tribologically advantageous PEEK-titanium material pairing is present between the bearing bushing 18 and the impeller pin 190, which is very low friction and wear-resistant.
[0020] The blood flow inside the housing 15 is produced by the rotation of the impeller 19. The spider bearing 17 comprises a plurality of inlet openings for the blood. There are nonetheless pressure losses in the region of the spider bearing, because the spider bearing 17 constricts the cross-section thus creating a bottleneck. In the region of the base of the impeller 19, there are openings 22 in the housing 15 of the micropump 10, through which the fluid to be moved, in particular the blood, flows out.
[0021] FIG. 2 shows the region of the sliding bearing 16 for the radial support of the impeller pin 190 of the impeller 19 with the impeller blades 12 as a component of a micropump 10 according to FIG. 1 in a schematic longitudinal section. The impeller pin 190 is rotatably mounted inside the bearing bushing 18, whereby a narrow bearing gap 31 is provided between the impeller pin 190 and the bearing bushing 18. The bearing bushing 18 is located inside the spider bearing 17. The regions 32 indicate the openings of the spider bearing 17 through which the fluid, in particular the blood, can flow.
[0022] FIG. 3, on the other hand, shows a preferred embodiment of a sealed micropump 100 according to the invention, whereby this figure also shows the region of the sliding bearing 116. The section of the sealed micropump 100 according to the invention shown here shows the impeller pin 1190 of the impeller 119 with the impeller blades 112, whereby the impeller pin 1190 is rotatably mounted in the sliding bearing 116. Inside the housing 150 of the micropump 100, the spider bearing 117 is located in the region of the radial sliding bearing 116. In the region of the sliding bearing 116, the impeller pin 1190 is tapered. The tapering 1190 is surrounded by a sheathing 118. This sheathing 118 is made of a material different from that of the spider bearing 117. The sheathing 118 can in particular be made of PEEK and the spider bearing 117 can be made of a metallic material, in particular titanium.
[0023] Between the sheathing 118 and the spider bearing 117, there is a narrow bearing gap 131. The impeller pin 1190 sheathed with PEEK therefore rotates in the central recess of the spider bearing 117, thus realizing the tribologically advantageous material pairing of PEEK and titanium, for example. In comparison with a sliding bearing of FIG. 2, in the solution according to the invention the bearing bushing 18 is, in a sense, replaced by the sheathing 118, whereby the overall diameter remains unchanged. As a result of this measure, the space required by the bearing bushing 18 can be used for other purposes, and the openings 132 inside the spider bearing 117, which are provided for the fluid flow, can even be enlarged. Thus, with the same functional bearing dimensions (e.g. bearing diameter 1 mm, bearing gap 10 μm and wall thickness of the sheathing 0.25 mm), there is more cross-section available for the flow.
[0024] The sheathing 118 can particularly preferably also be implemented in the form of a cap 1180 which extends the sheathing 118 upstream and, as a result of being suitably shaped, provides advantages in terms of flow. The shape of the cap 1180 can in particular have a diameter that decreases upstream, in particular in a conical or semi-ellipsoidal shape. Improved flow control around the bearing 116 can thus be realized, as a result of which pressure losses are additionally reduced and the efficiency of the micropump 100 is increased.
[0025] FIG. 4 illustrates the configuration of the micropump 100 according to the invention in the region of the sliding bearing (Sub-figure 4B) in comparison to the sliding bearing of a micropump 10 of FIG. 1 (Sub-figure 4A) in cross-section. The illustration in Sub-figure A shows the sliding bearing with the impeller pin 19, which is rotatably mounted inside the bearing bushing 18, separated by the bearing gap 31. The bearing bushing 18 is located inside the spider bearing 17, which is secured inside the housing 15 of the micropump 10 via the spider bearing struts 170. The space 32 through which the fluid can flow is located between the individual spider bearing struts 170. In comparison with the configuration according to the invention in Sub-figure B, it becomes clear that the corresponding region 132 is significantly enlarged in the solution according to the invention. Sub-figure B shows the tapered region of the impeller pin 1190, which is directly surrounded by the sheathing 118 made of a different material. The narrow bearing gap 131 is located between the sheathing 118 and the interior of the spider bearing 117 (central recess of the spider bearing 17). The interior of the spider bearing 117 is connected to the housing 115 of the micropump 100 via the spider bearing struts 1170. This configuration makes it possible to enlarge the region 132 for fluid flow substantially in comparison to the sliding bearings according to FIG. 1. The micropump 100 according to the invention therefore produces significantly less pressure loss in the upstream region of the radial sliding bearing of the impeller pin.
[0026] Such a micropump can be used particularly advantageously as a blood pump for a cardiac support system, for example.
