Blood pump

Abstract

The present invention relates to a blood pump 10 comprising a pump housing 12 having a blood flow inlet 14 and a blood flow outlet 16, a pump element 18 disposed in the pump housing 12 so as to be rotatable about an axis of rotation AR for conveying blood from the blood flow inlet 14 to the blood flow outlet 16, and a drive unit 22 for rotating the pump element 18. The drive unit 18 comprises a first drive unit element 24, a second drive unit element 26 and a third drive unit element 28, wherein the second drive unit element 26 is disposed between the first drive unit element 24 and the third drive unit element 28 in an axial direction along the axis of rotation AR. The first drive unit element 24 and the third drive unit element 28 are of a first type, and the second drive unit element 26 is of a second type, wherein the second type is different from the first type.

Description

[0001] BLOOD PUMP

[0002] The present invention relates to a blood pump. In particular, the present invention relates to an intravascular blood pump for percutaneous insertion into a patient’s blood vessel, to support a blood flow in a patient’s blood vessel. The blood pump may also be an intracardiac blood pump or any other kind of ventricular assist device.

[0003] BACKGROUND OF THE INVENTION

[0004] Various blood pumps are known from the prior art, e.g. axial blood pumps, centrifugal (i.e. radial) blood pumps or mixed-type blood pumps, where the blood flow is caused by axial forces as well as by radial forces. Such blood pumps may be introduced into the heart of a patient to support the blood flow from the heart into an artery e.g., the aorta. The blood pump may be introduced percutaneously during a cardiac procedure through the vascular system, such as by a catheterization procedure. After the blood pump has been placed, blood is unloaded by the blood pump from the left ventricle into the aorta to restore adequate systemic blood flow. Therefore, a blood pump typically comprises a pump housing having a blood flow inlet and a blood flow outlet connected by a blood flow passage, a pump element in form of an impeller disposed in said pump housing being rotatable about an axis of rotation for conveying blood from the blood flow inlet to the blood flow outlet along a blood flow passage. Further, such blood pumps comprise a drive unit configured to rotate the impeller. An according blood pump is known from e.g., WO 2021 / 043776 A1 .

[0005] The blood pump disclosed in WO 2021 / 043776 A1 comprises a drive unit configured to rotate the impeller contact free. Therefore, the impeller is magnetically coupled to a stator element in that the impeller comprises a rotor element which is disposed adjacent to electrically magnetized zones in the stator element. The rotor element is typically composed of magnets. Based on the attractive force between the magnets of the impeller and the magnetized zones in the stator element, rotation can be transmitted to the impeller. In particular, a rotating magnetic field is established within the stator element which rotates the impeller in that a control unit applies appropriate voltage to the stator element in a controlled manner.

[0006] However, there is the need for more compact and efficient drive units. Furthermore, there is also the need to provide blood pumps which operate with reduced bearing loads.

[0007] SUMMARY OF THE INVENTION

[0008] Provided is a blood pump comprising a pump housing, a pump element and a drive unit. The pump housing has a blood flow inlet and a blood flow outlet. The pump element may be an impeller. The pump element is disposed in the pump housing so as to be rotatable about an axis of rotation for conveying blood from the blood flow inlet to the blood flow outlet along a blood flow passage. The drive unit is configured to rotate the pump element. The drive unit further comprises a first drive unit element, a second drive unit element and a third drive unit element. The second drive unit element is disposed between the first drive unit element and the third drive unit element in an axial direction along the axis of rotation. The first drive unit element and the third drive unit element are of a first type and the second drive unit element is of a second type. The second type is different from the first type.

[0009] In other words, the first drive unit element and the third drive unit element are of the same type and may be stator elements or rotor elements. The second drive unit element is of another type and is the other one of a stator element or a rotor element and is sandwiched between the first drive unit element and the third drive unit element in the axial direction. This configuration increases the efficiency of the drive unit. Furthermore, by choosing a suitable axial extension for the magnetic gaps between the drive unit elements, the axial load applied to the pump element and to provided bearing members during operation of the blood pump can be significantly reduced for certain operating conditions of the blood pump in accounting for the axial force component generated by the hydraulic thrust induced by rotation of the pump element. Due to the attractive magnetic forces between a stator element and a rotor element an axial force component is generated. However, as either a second stator element or a second rotor element is provided, the generated axial force components can cancel each other out by setting the axial extension of the magnetic gaps to an appropriate value.

[0010] Accordingly, a first magnetic gap may be provided between the first drive unit element and the second drive unit element and a second magnetic gap may be provided between the third drive unit element and the second drive unit element. Preferably, the axial extensions of the first magnetic gap and the second magnetic gap are dimensioned so that the axial force components cancel each other out for the optimum operating conditions i.e., forthose conditions which prevail during usage of the blood pump when implanted into a human body. In other words, an axial extension of the first magnetic gap and an axial extension of the second magnetic gap are selected so that axial force components established between (i) the first drive unit element and the second drive unit element and (ii) the third drive unit element and the second drive unit element during operation of the blood pump account for the hydraulic thrust induced by rotation of the pump element.

[0011] Thus, selecting the axial extension of the first magnetic gap and the axial extension of the second magnetic gap to provide respective axial force components accounting for an axial force component generated by the hydraulic thrust of the pump element during operation of the blood pump leads to some kind of “preload” force in one axial direction which is then equalized again by the axial force component induced by rotation of the pump element during operation of the blood pump i.e., the induced hydraulic thrust of the pump element. This leads to a minimized overall axial force component acting on the bearing members. The axial extension of the first magnetic gap and the axial extension of the second magnetic gap may be different.

[0012] Especially in case when the first drive unit element and the third drive unit element are provided as rotor elements having a different magnetic field strength, the axial extension of said magnetic gap provided between the respective drive unit element having the lower magnetic field strength and the second drive unit element is smaller than the magnetic gap provided between the other one of the respective drive unit elements and the second drive unit element. In other words, if the first drive unit element has a smaller magnetic field strength than the third drive unit element, the axial extension of the first magnetic gap is smaller than the axial extension of the second magnetic gap. Accordingly, when the first drive unit element and the third drive unit element are provided as stator elements, the resulting axial force components are set by the respective cross-sectional area of the respective stator element. As the cross-sectional areas may be different, the resulting axial force components may also be different. Hence, this difference in the axial force components may further be accounted for in selecting appropriate axial extension of the first magnetic gap and the second magnetic gap.

[0013] Thus, the axial extensions of the first magnetic gap and the second magnetic gap are selected so that the overall axial force component during operation of the blood pump acting on the bearing members is minimized and preferably 0 N. The overall axial force component is a sum of the axial force components on the one hand established between (i) the first drive unit element and the second drive unit element and (ii) the second drive unit element and the third drive unit element and (iii) the axial force component generated by the hydraulic thrust of the pump element induced by rotation of the pump element.

[0014] According to a first aspect, the first drive unit element of the first type may be a first rotor element, the third drive unit element of the first type may be a second rotor element and the second drive unit element of the second type may be a first stator element. The first rotor element and the second rotor element may be connected to the pump element so as to rotate together with the pump element, wherein the first stator element may be fixed within the pump housing and disposed about the axis of rotation. According to this aspect, two rotor elements and one stator element are provided which compose the drive unit.

[0015] The pump element may comprise the second rotor element. The second rotor element may be directly fixed to the pump element or may be embedded in the pump element.

[0016] The blood pump may further comprise a shaft coaxial to the axis of rotation. The shaft may comprise a first axial end and a second axial end and may extend through the first stator element. The first rotor element is preferably attached to the shaft in the area of the first axial end. The pump element is preferably attached to the second axial end of the shaft. Hence, the rotation generated by the interaction between the first stator element and the first rotor element is transferred to the shaft and thus to the pump element attached to the shaft.

[0017] The second rotor element is preferably attached to the shaft between the first axial end of the shaft and the second axial end of the shaft. Thus, the rotation generated by the interaction between the first stator element and the second rotor element is transferred to the shaft and thus to the pump element attached to the shaft.

[0018] According to a second aspect, the first drive unit element of the first type may be a first stator element, the third drive unit element of the first type may be a second stator element and the second drive unit element of the second type may be a first rotor element. The first rotor element may be connected to the pump element so as to rotate together with the pump element, wherein the first stator element and the second stator element may be fixed within the pump housing and disposed about the axis of rotation. According to this aspect, two stator elements and one rotor element are provided which compose the drive unit.

[0019] Preferably, the drive unit comprises a total of exactly three drive unit elements.

[0020] The blood pump may further comprise a shaft coaxial to the axis of rotation. The shaft may comprise a first axial end and a second axial end and may extend through the second stator element. The first rotor element is preferably attached to the shaft in the area of the first axial end and the pump element is preferably attached to the second axial end of the shaft. Hence, the rotation generated by the interaction between the first and second stator element and the first rotor element is transferred to the shaft and thus to the pump element attached to the shaft.

[0021] The blood pump may further comprise a first bearing member, wherein the first axial end of the shaft may be rotatably supported by the first bearing member. The first bearing member preferably is a pivot bearing. Preferably, the first bearing member is a bearing configured to support axial loads and radial loads. The first bearing member preferably comprises a first support surface and a ball, wherein the shaft preferably comprises a second support surface at the first axial end of the shaft. The ball is preferably disposed between the first support surface and the second support surface. Accordingly, small radial offsets or deflections of the shaft or the pump element, respectively, that may occur during operation of the blood pump may be compensated by the first bearing member.

[0022] The blood pump may further comprise a second bearing member. The second bearing member may be configured to support the shaft. The second bearing member is preferably disposed between the pump element and the drive unit in the axial direction. The second bearing member may also be configured to support the pump element. The second bearing member is preferably configured as a radial bearing i.e., a bearing intended to support radial loads. The second bearing member may also be configured to support radial loads and axial loads. The blood pump may comprise a purge arrangement. The purge arrangement may be configured to feed purge fluid through the blood pump or through parts of the blood pump respectively. The purge fluid may be blood or may be a liquid purge solution supplied externally to the blood pump. Purging of the blood pump avoids coagulation of blood and clotting and further cools the blood pump and the drive unit in particular.

[0023] The purge arrangement for a blood pump according to the first aspect may comprise a first purge channel connected to the blood flow passage. The purge arrangement may comprise a second purge channel connected to the first purge channel. The second purge channel may at least be disposed between the second rotor element and the first stator element. The purge arrangement may comprise a third purge channel at least connected to the second purge channel. The third purge channel may axially extend through the first stator element. The purge arrangement may comprise a fourth purge channel disposed radially inwardly of the first rotor element. The fourth purge channel may at least be connected to the third purge channel. The purge arrangement may comprise a fifth purge channel connected to the third purge channel. The fifth purge channel may be at least partially disposed between the first stator element and the first rotor element. The pump housing may comprise at least one purge opening and the fourth purge channel may be connected to the at least one purge opening.

[0024] The purge arrangement for a blood pump according to the second aspect may comprise a first purge channel connected to the blood flow passage. The purge arrangement may comprise a second purge channel connected to the first purge channel. The second purge channel may axially extend through the second stator element. The purge arrangement may comprise a third purge channel The third purge channel may at least partially be disposed radially inwardly of the first rotor element. The second purge channel may be connected to the third purge channel. The pump housing may comprise at least one purge opening. The purge arrangement may comprise a fourth purge channel disposed between the first rotor element and the second stator element. The fourth purge channel may be connected to the third purge channel and the at least one purge opening. The purge arrangement may comprise a fifth purge channel disposed between the first rotor element and the first stator element. The fifth purge channel may be connected to the at least one purge opening the third purge channel.

[0025] The pump element may comprise at least one first opening and at least one second opening. The second opening may be coaxial with the axis of rotation. The first purge channel may extend between the at least one first opening and the second opening. Preferably, the first opening opens into the blood flow passage. Thus, a portion of the blood entering through the blood flow inlet of the pump housing and being conveyed along the blood flow passage enters into the interior of the pump element through the first opening and is then guided along the channels of the purge arrangement for purging the blood pump. As an alternative, the blood pump housing may comprise a purge fluid inlet connected to the purge arrangement. A purge fluid line for supplying purge fluid externally may be connected to the purge fluid inlet. Thus, the externally supplied purge fluid is guided along the channels of the purge arrangement for purging the blood pump.

[0026] It has to be emphasized that a stator element in the sense of the present invention may also comprise a plurality of stators. As such, a rotor element in the sense of the present invention may also comprise a plurality of rotors or magnets respectively.

[0027] Preferably, the first stator element is a six slot stator. Preferably, the second stator element is a six slot stator. Preferably, the first rotor element is a four pole rotor. Preferably, the second rotor element is a four pole rotor.

[0028] BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The foregoing summary as well as the following detailed description of preferred embodiments will be better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, reference is made to the drawings. However, the scope of the disclosure is not limited to the specific embodiments disclosed in the drawings.

[0030] In the drawings:

[0031] Fig. 1 is a perspective view of a blood pump according to a first embodiment,

[0032] Fig. 2 is a side view of the blood pump of Fig. 1 ,

[0033] Fig. 3 is a cross section along the line A-A shown in Fig. 2,

[0034] Fig. 4 is a perspective view of a blood pump according to a second embodiment,

[0035] Fig. 5 is a side view of the blood pump of Fig. 4,

[0036] Fig. 6 is a cross section along the line B-B shown in Fig. 5,

[0037] Fig. 7 is a perspective view of a blood pump according to a third embodiment,

[0038] Fig. 8 is a side view of the blood pump of Fig. 7,

[0039] Fig. 9 is a cross section along the line C-C shown in Fig. 8,

[0040] Fig. 10 is a perspective view of a blood pump according to a fourth embodiment, Fig. 11 is a side view of the blood pump of Fig. 10,

[0041] Fig. 12 is a cross section along the line D-D shown in Fig. 11 ,

[0042] Fig. 13 is a perspective view of a blood pump according to a fifth embodiment,

[0043] Fig. 14 is a side view of the blood pump of Fig. 13, and

[0044] Fig. 15 is a cross section along the line E-E shown in Fig. 14.

[0045] DETAILED DESCRIPTION

[0046] Fig. 1 depicts a perspective view of a blood pump 10 according to a first embodiment. The blood pump 10 comprises a pump housing 12 having a blood flow inlet 14 and blood flow outlets 16. The pump housing 12 comprises a cylindrical portion 66 and an attachment portion 70 connected to the cylindrical portion 66 by a reduced portion 68. The attachment portion 70 has a smaller diameter than the cylindrical portion 66. The attachment portion 70 is configured to receive or support further elements, like a catheter or a nitinol coil. In this exemplary embodiment, the blood flow inlet 14 is provided at a face of the cylindrical portion 66 of the pump housing 12 and the blood flow outlets 16 are provided on a circumference of the cylindrical portion 66 of the pump housing 12. In this particular embodiment, a total of six blood flow outlets 16 are provided which are evenly distributed on an outer peripheral surface of the cylindrical portion 66 of the pump housing 12.

[0047] A pump element 18 is disposed in the pump housing 12, see also Fig. 3. In this exemplary embodiment, the pump element 18 is an impeller. The impeller 18 is rotatable about an axis of rotation AR for conveying blood from the blood flow inlet 14 to the blood flow outlets 16 along a blood flow passage 20. As shown in Fig. 3, a drive unit 22 is provided which is configured to rotate the impeller 18 about the axis of rotation AR so as to established the blood flow from the blood flow inlet 14 to the blood flow outlets 16.

[0048] The drive unit 22 is disposed about the axis of rotation AR and comprises a first drive unit element of a first type in form of a first rotor element 24, a second drive unit element of a second type in form of a first stator element 26 and a third drive unit element of a first type in form of a second rotor element 28. When viewed along the axis of rotation AR in direction to the blood flow inlet 14, the second rotor element 28 is disposed closest to the blood flow inlet 14 with the first stator element 26 being disposed between the first rotor element 24 and the second rotor element 28. In this embodiment, the first stator element 26 is a six slot stator. The first stator element 26 is fixed within the pump housing 12. In this exemplary embodiment, the drive unit 22 comprises a total of exactly three drive unit elements 24, 26, 28. In this embodiment, the first rotor element 24 is a four pole rotor being rotatable about the axis of rotation AR. Accordingly, the second rotor element 28 is also a four pole rotor being rotatable about the axis of rotation AR. The first rotor element 24 and the second rotor element 28 are operatively coupled to the impeller 18 so that rotation of the first rotor element 24 and the second rotor element 28 is transferred to the impeller 18.

[0049] Therefore, a shaft 30 extends axially along the axis of rotation AR within the pump housing 12. The shaft 30 comprises a first axial end 32 and a second axial end 34. The second axial end points towards the blood flow inlet 14. The impeller 18 is attached to the second axial end 34 in a torque transmitting manner so that the impeller 18 and the shaft 30 rotate together. For instance, the impeller 18 may be glued to the second axial end 34 of the shaft 30.

[0050] In this embodiment, the first rotor element 24 is fixed to the shaft 30 in a torque transmitting manner. As shown in Fig. 3, the first rotor element 24 is fixed to the shaft 30 in the area of the first axial end 32 of the shaft 30. The shaft 30 extends through the first stator element 26 and the second rotor element 28 is fixed to the shaft 30 in a torque transmitting manner between the first stator element 26 and the impeller 18. The first rotor element 24 and the second rotor element 28 may be fixed to the shaft 30 by any suitable method e.g., by gluing. In the assembled state, a first magnetic gap 36 is provided defining the axial distance between the first rotor element 24 and first stator element 26. Further, a second magnetic gap 38 is provided defining the axial distance between the first stator element 26 and the second rotor element 28.

[0051] To rotate the impeller 18, a rotating magnetic field is established within the first stator element 26 which rotates the first rotor element 24 and the second rotor element 28 together with the shaft 30 and the impeller 18 about the axis of rotation AR. The rotation of the impeller 18 is controlled in that a control unit applies appropriate voltage to the stator element 26 in a controlled manner. Accordingly, the shaft 30 is also configured to support the magnetic forces established in the axial direction by the first rotor element 24 and the second rotor element 28.

[0052] To allow for smooth rotation of the shaft 30, the blood pump 10 comprises a first bearing member 40 and a second bearing member 48. In this exemplary embodiment, the first bearing member 40 is configured as a pivot bearing. The first axial end 32 of the shaft 30 is rotatably supported by the first bearing member 40. Therefore, the first bearing member 40 comprises a first support surface 42 provided at the pump housing 12. In this exemplary embodiment, the first support surface 42 is a concave surface and may be a spherical cap. The first bearing member 40 comprises a ball 44 supported at the first support surface 42. A second support surface 46 is provided at the first axial end 32 of the shaft 30. The second support surface 46 is a concave surface and may be a spherical cap. The second support surface 46 abuts the ball 44 so that the ball 44 is supported at the second support surface 46. This configuration of the first bearing member 44 allows for accommodation to slight radial offsets or deflections of the shaft 30 that may occur during operation of the blood pump 10. As shown in Fig. 3, the first bearing member 40 is configured to support axial loads and radial loads of the shaft 30. In the embodiment shown, the axial forces induced by rotation of the impeller 18 are directed towards the first bearing member 40 to inhibit lifting of the impeller 18. The second bearing member 48 is provided between the second rotor element 28 and the impeller 18. In this exemplary embodiment, the second bearing member 48 is a slide bearing configured to support radial loads of the shaft 30. Therefore, the pump housing 12 comprises a tapering portion 50 tapering from the outer peripheral surface of the pump housing 12 towards the shaft 30 or axis or rotation AR respectively. The tapering portion 50 is provided radially inwardly of the blood flow outlets 16 and comprises the second bearing member 48 supporting the shaft 30. Of course, the second bearing member 48 may also be configured differently e.g., as a bearing member configured to support radial loads and axial loads.

[0053] The axial extensions of the first magnetic gap 36 and the second magnetic gap 38 are selected so that the resulting axial force components between the first rotor element 24 and the first stator element 26 on the one hand and the first stator element 26 and the second rotor element 28 on the other hand during operation of the blood pump 10 cancel each other out. This effect depends on the operating conditions of the blood pump 10 (e.g., speed of rotation, pressure etc.) so that the axial extensions of the first magnetic gap 36 and the second magnetic gap 38 are preferably optimized for the optimum operating conditions. To account for possible axial forces induced by the rotation of the impeller 18 in this embodiment, the first magnetic gap 36 and the second magnetic gap 38 are set so that the magnetic forces between first stator element 22 and the second rotor element 28 are larger than the magnetic forces between the first stator element 22 and the first rotor element 24.

[0054] Referring to Fig. 3, the second rotor element 28 has a larger volume than the first rotor element 24, which leads to the second rotor element 28 having a higher magnetic field strength than the first rotor element 24. To have the resulting axial force components cancel each other out (i.e., to have an overall axial force component of ON), the axial extension of the first magnetic gap 36 should be smaller than the axial extension of the second magnetic gap 38. Taking further into account that rotation of the impeller 18 leads to a hydraulic thrust and a further axial force component in the direction of the blood flow inlet 14, an axial “preload” force component is additionally factored in the direction of the first bearing member 40. This additional axial “preload” force component is achieved in enlarging the axial extension of the first magnetic gap 36 or in making the axial extension of the second magnetic gap 38 smaller. In total this leads to a deviation from equalized axial force components during non- operation of the blood pump 10, but to equalized axial force components during operation of the blood pump 10. Accordingly, the axial forces acting on the first bearing member 40 and the second bearing member 48 during operation of the blood pump 10 are minimized.

[0055] Preferably, the magnetic forces set by the second magnetic gap 38 are slightly larger than the sum of the axial forces induced by rotation of the impeller and the magnetic forces set by the first magnetic gap 36. Furthermore, a mechanical stop may also be provided e.g., in that the second bearing member 48 is configured to axially support the shaft 30.

[0056] The blood pump 10 according to the first embodiment further comprises a purge arrangement 52. The purge arrangement 52 comprises a plurality of purge channels 54 - 60. The blood pump 10 further comprises a purge fluid inlet 62 provided at the pump housing 12 and connected to the purge channels 54 - 60 as will be described in more detail below. As shown in Figs. 2 and 3, the purge fluid inlet 62 is disposed at the axial end of the blood pump 10 being opposite to the blood flow inlet 14. A purge solution may be introduced through the purge fluid inlet 62 and may be guided along the purge channels 54 - 60 of the purge arrangement 52 to cool the drive unit 22, to avoid ingression of blood into the drive unit 22 and to avoid blood coagulation.

[0057] In this exemplary embodiment, the purge arrangement 52 comprises a first purge channel 54, a second purge channel 56, a third purge channel 58 and a fourth purge channel 60. The first purge channel 54 is disposed between the impeller 18 and an axial end face of the tapering portion 50. The second purge channel 56 is disposed between an inner surface of the tapering portion 50 and the second rotor element 28 and between the second rotor element 28 and the first stator element 26. In other words, the second purge channel 56 is partially composed of the second magnetic gap 38. The first purge channel 54 extends through the second bearing member 48 and is connected to the second purge channel 56. The third purge channel 58 extends axially through the first stator element 28 along the outer peripheral surface of the shaft 30 and is connected to the second purge channel 56. The fourth purge channel 60 is partially disposed radially inwardly of the first rotor element 24 and is further connected to the purge fluid inlet 62. Of course, the purge arrangement 52 may be configured so that purge fluid is introduced into all cavities of the blood pump 10.

[0058] For purging the blood pump 10, a liquid purge solution is introduced via the purge fluid inlet 62. The purge solution flows along the purge fluid inlet 62 which opens into the interior of pump housing 12 at the first support surface 42. The purge solution flows along the ball 44 and enters the fourth purge channel 60. The purge solution further flows along the third purge channel 58 radially inwardly of the first stator element 26 and then enters the second purge channel 56. The purge solution in the second purge channel 56 flows along the second magnetic gap 38 and then between the second rotor element 28 and the inner surface of the tapering portion 50. In the area of the second bearing member 48, the second purge channel 56 is connected to the first purge channel 54, so that the purge solution flows axially through the second bearing member 48 and exits into the blood flow passage 20, as the first purge channel 54 opens into the blood flow passage 20. Thus, the first bearing member 40 and the second bearing member 48 are purged and coagulation of blood is greatly inhibited.

[0059] Next, further embodiments of the blood pump 210, 310, 410, 510 according to the present disclosure will be described with reference to Figs. 4 to 15. However, only the differences between the different embodiments will be explained and like elements are denoted by identical or similar reference numbers.

[0060] Figs. 4 to 6 depict a second embodiment of a blood pump 210 according to the present disclosure. The blood pump 210 according to the second embodiment differs from the blood pump 10 according to the first embodiment in the configuration of the impeller 218, the drive unit 222, the second bearing member 248 and the purge arrangement 252.

[0061] In this embodiment, the impeller 218 comprises the second rotor element 228 in that the second rotor element 228 is embedded in the impeller 218, see Fig. 6. The impeller 218 is attached to the second axial end 34 of the shaft 20 so that the rotation magnetic field established in the first stator element 26 causes rotation of the first rotor element 24 and the second rotor element 228 and in consequence of the impeller 218.

[0062] Furthermore, the second bearing member 248 is disposed in the area of the blood flow inlet 14 and directly supports the impeller 218. As in the first embodiment shown in Figs. 1 to 3, the second bearing member 248 is configured as a slide bearing configured to support radial loads of the impeller 218, but may also be configured differently as described above. During operation of the blood pump 210, the second bearing member 248 is purged by blood sucked into the pump housing 12 via the blood flow inlet 14 due to rotation of the impeller 218.

[0063] The first purge channel 254 of the purge arrangement 252 is disposed at the transition between the impeller 218 and the blood flow outlet 16 and directly merges into the second purge channel 56. The second purge channel 56 coincides with the second magnetic gap 38 and opens into the third purge channel 58 disposed between the shaft 30 and the first stator element 26. The third purge channel 58 merges with the fourth purge channel 60, which is partially disposed radially inwardly of the first rotor element 24. The purge arrangement 252 further comprises a fifth purge channel 261 which is partially disposed between the first rotor element 24 and the first stator element 26. In other words, the fifth purge channel 261 is partially composed of the first magnetic gap 36. The pump housing 12 comprises a plurality of purge openings 264 which are connected to the fourth purge channel 60 and the fifth purge channel 261 . In this exemplary embodiment, the pump housing 12 comprises a total of six purge openings 264 which are evenly distributed around the circumference of the pump housing 12. As shown in Figs. 4 to 6, the purge openings 264 are mainly provided on the reduced portion 68 of the pump housing 12 i.e., between the cylindrical portion 66 and the attachment portion 70 of the pump housing 12. Each purge opening 264 has an elongated shape and extends along the reduced portion 68 in the axial direction i.e., along the axis of rotation AR. As shown in Fig. 5, each of the purge openings 264 may extend into the cylindrical portion 66 of the pump housing 12. In this embodiment, a purge fluid inlet is not provided. Rather, purging of the blood pump 10 is induced by blood guided along the purge arrangement 252. In particular, the blood purging can be provided in a direction from the first purge channel 254 to the purge openings 264 or in a direction from the purge openings 264 to the first purge channel 254. To facilitate the blood flow for purging, the axial end face of the impeller 218 facing the first stator element 26 can be provided with secondary pump elements e.g., blades or protrusions generating the blood flow for purging. Of course, second pump elements may also be provided at the first rotor element 24. In this embodiment, secondary pump elements are provided as radial blades 72 at the first rotor element 24.

[0064] When purging from the first purge channel 254 in direction to the purge openings 264, the blood flows from the blood flow passage 20 into the first purge channel 254 and then into the second purge channel 56. As the second purge channel 56 opens into the third purge channel 58, the blood further flows in the axial direction between the first stator element 26 and the shaft 30 and exits into the fourth purge channel 60 and the fifth purge channel 261 . The first bearing member 40 is thus purged and the blood then exits the pump housing 12 through the purge openings 264.

[0065] When purging from the purge openings 264 in the direction of the first purge channel 254, secondary pump elements provided at the impeller 218 and / or at the first rotor element 24 cause blood to be sucked through the purge openings 264 into the interior of the pump housing 12. The blood sucked through the purge openings 264 is conveyed along the fourth purge channel 60, purges the first bearing member 40 and then exits into the third purge channel 58. In the third purge channel 58, the blood flows in the axial direction radially inwardly of the first stator element 26 along the shaft 30 and exits into the second purge channel 56. The second purge channel 56 opens into the first purge channel 254 and the blood is then further conveyed via the blood flow passage 20 and exits the pump housing 12 via the blood flow outlets 16.

[0066] Figs. 7 to 9 depict a third embodiment of a blood pump 310 according to the present disclosure. The blood pump 310 according to the third embodiment differs from the blood pump 210 according to the second embodiment in the configuration of the impeller 318, the drive unit 322 and the purge arrangement 352.

[0067] As shown in Fig. 7 and Fig. 9, the impeller 318 comprises a plurality of first openings 374 on its outer peripheral surface and a second opening 376 on its axial end opposite to the second bearing member 248 i.e., the axial end facing the first stator element 26. In this exemplary embodiment, the impeller 318 comprises two first openings 374. The first purge channel 354 is disposed within the impeller 318 and connects the first openings 374 and the second opening 376. The second opening 376 is coaxially aligned with the axis or rotation AR and opens into the second purge channel 56 and the third purge channel 58. As depicted in Fig. 9, the first openings 374 extend through the impeller 318 and open into the first purge channel 354. Furthermore, the extension of the first openings 374 is inclined relative to the axis of rotation AR.

[0068] The impeller 318 comprises the second rotor element 328 which is embedded in the impeller 318. However, the second rotor element 328 has a smaller radial extension compared to the second rotor element 228 of the blood pump 210 according to the second embodiment. The second rotor element 326 may also have a greater axial extension compared to the second rotor element 228 of the blood pump 210 according to the second embodiment. The adaption of the second rotor element 328 is necessary due to the first purge channel 354 being disposed inside the impeller 318.

[0069] To facilitate the blood flow for purging, the axial end face of the impeller 318 facing the first stator element 26 can be provided with secondary pump elements e.g., blades or protrusions generating the blood flow for purging

[0070] During operation of the blood pump 310, blood is sucked from the blood flow passage 20 into the first purge channel 354 via the first openings 374. The blood then exits the first purge channel 354 via the second opening 376 and a portion of the blood is further conveyed along the second purge channel 56 and exits the pump housing 12 via the blood flow outlets 16. Another portion of the blood is conveyed along the third purge channel 58. The blood further flows in the axial direction between the first stator element 26 and the shaft 30 and exits into the fourth purge channel 60 and the fifth purge channel 261 . The first bearing member 40 is thus purged and the blood then exits the pump housing 12 through the purge openings 264.

[0071] Figs. 10 to 12 depict a blood pump 410 according to a fourth embodiment of the present disclosure. The blood pump 410 according to the fourth embodiment differs from the blood pump 10 according to the first embodiment in the configuration of the drive unit 422 and the purge arrangement 452.

[0072] The drive unit 422 is disposed about the axis of rotation AR and comprises a first drive unit element of a first type in form of a first stator element 424, a second drive unit element of a second type in form or a first rotor element 426 and a third drive unit element of a first type in form of a second stator element 428. When viewed along the axis of rotation AR in direction to the blood flow inlet 14, the second stator element 428 is disposed closest to the blood flow inlet 14 with the first rotor element 426 being disposed between the first stator element 424 and the second stator element 428. In this embodiment, the first stator element 424 is a six slot stator. The first stator element 424 is fixed within the pump housing 12. The second stator element 428 is a six slot stator. The second stator element 428 is fixed within the pump housing 12.

[0073] In this embodiment, the first rotor element 426 is a four pole rotor being rotatable about the axis of rotation AR. The first rotor element 428 is operatively coupled to the impeller 18 so that rotation of the first rotor element 428 is transferred to the impeller 18. Therefore, the shaft 430 is of different construction as in the embodiments described above. As can be seen in Fig. 12, the shaft 430 extends axially along the axis of rotation AR within the pump housing 12. The shaft 430 comprises a first axial end 432 and a second axial end 434. The second axial end 434 points towards the blood flow inlet 14. The impeller 18 is attached to the second axial end 434 in a torque transmitting manner so that the impeller 18 and the shaft 430 rotate together. For instance, the impeller 18 may be glued to the second axial end 434 of the shaft 430.

[0074] In this embodiment, the first rotor element 426 is fixed to the shaft 430 in a torque transmitting manner. As shown in Fig. 12, the first rotor element 426 is fixed to the shaft 430 in the area of the first axial end 432 of the shaft 430. The first rotor element 426 may be fixed to the shaft 430 by any suitable method e.g., by gluing. As shown, the shaft 430 extends only through the second stator element 428 and not through the first stator element 424. In the assembled state, a first magnetic gap 436 is provided defining the axial distance between the first rotor element 426 and the first stator element 424. Further, a second magnetic gap 438 is provided defining the axial distance between the first rotor element 426 and the second stator element 428.

[0075] To rotate the impeller 18, a rotating magnetic field is established in each of the first stator element 424 and the second stator element 428, which rotates the first rotor element 426 together with the shaft 430 and the impeller 18 about the axis of rotation AR. The rotating magnetic fields in the stator elements 424, 428 may be harmonized or may be shifted by e.g., 180°. The rotation of the impeller 18 is controlled in that a control unit applies appropriate voltage to the first stator element 424 and the second stator element 428 in a controlled manner.

[0076] In this embodiment, the first rotor element 426 establishes an identical magnetic field strength in relation to the first stator element 424 and in relation to the second stator element 428. Thus, resulting axial force components depend on the cross-sectional areas of the first stator element 424 and the second stator element 428. Hence, in case the first stator element 424 and the second stator element 428 have a different cross-sectional area, the difference in the resulting axial force components can be accounted for by adjusting the axial extension of the first magnetic gap 436 and the second magnetic gap 438.

[0077] Irrespectively of the cross-sectional area of the first stator element 424 and the second stator element 428, an additional axial force component in the direction of the blood flow inlet 14 is generated by the hydraulic thrust of the impeller 18 induced by rotation of the same. To account for this additional axial “preload” force component, either the axial extension of the first magnetic gap 436 is enlarged or the axial extension of the second magnetic gap 438 is made smaller. In total this leads to a deviation from equalized axial force components during non- operation of the blood pump 410, but to equalized axial force components during operation of the blood pump 410. Accordingly, the axial forces acting on the first bearing member 440 and the second bearing member 448 during operation of the blood pump 410 are minimized.

[0078] In this embodiment, the first bearing member 440 is also configured as a pivot bearing and the first axial end 432 of the shaft 430 is rotatably support by the first bearing member 440. As shown in Fig. 12, the ball 444 is supported by the first support surface 442 and the second support surface 446. The first support surface 442 is provided on a housing member 478 which encases the first stator element 424. In particular, the first support surface 442 is provided on an axial face of the housing member 478 facing the first rotor element 426.

[0079] This configuration of the first bearing member 440 allows for accommodation to slight radial offsets or deflections of the shaft 430 that may occur during operation of the blood pump 410. As shown in Fig. 12, the first bearing member 440 is configured to support axial loads and radial loads of the shaft 430.

[0080] The second bearing member 448 is provided between the second stator element 428 and the impeller 18. In this exemplary embodiment, the second bearing member 448 is a slide bearing configured to support radial loads of the shaft 430. Therefore, the pump housing 12 comprises a tapering portion 450 tapering from the outer peripheral surface of the pump housing 12 towards the shaft 430 or axis of rotation AR respectively. The tapering portion 450 is provided radially inwardly of the blood flow outlets 16 and comprises the second bearing member 448 supporting the shaft 430.

[0081] As in the other embodiments, the axial extensions of the first magnetic gap 436 and the second magnetic gap 438 are selected so that the resulting axial force components between the first rotor element 426 and the first stator element 424 on the one hand and the second stator element 428 on the other hand during operation of the blood pump 410 cancel each other out. This effect depends on the operating conditions of the blood pump 410 (e.g., speed of rotation, pressure etc.) and the bearing members used so that the axial extensions of the first magnetic gap 436 and the second magnetic gap 438 are preferably optimized for the optimum operating conditions.

[0082] In this embodiment, the purge arrangement 452 comprises the first purge channel 454 disposed between the impeller 18 and the second stator element 428. As shown in Fig. 12, the first purge channel 454 is defined by the axial end surface of the impeller 18 facing the second stator element 428 and the end surface of the tapering portion 450 facing the impeller 18. The second purge channel 456 is connected to the first purge channel 454 and extends axially through the second stator element 428. In particular, the second purge channel 454 also extends through the second bearing member 448. The third purge channel 458 is partially disposed radially inwardly of the first rotor element 426 and surrounds the first bearing member 440. The third purge channel 458 is further connected to the purge fluid inlet 462. As depicted in Fig. 12, the purge fluid inlet 462 penetrates through the housing member 478 and opens into the third purge channel 458 at the first support surface 442. The liquid purge solution introduced through the purge fluid inlet 462 flows along the ball 444 and enters the third purge channel 458. The purge solution then further flows along the second purge channel 456 through the second bearing member 448 and exits into the first purge channel 454. The purge solution then flows along the first purge channel 454 and exits into the blood flow passage 20. Thus, the first bearing member 440 and the second bearing member 448 are purged and coagulation of blood is greatly inhibited.

[0083] Figs. 13 to 15 depict a blood pump 510 according to a fifth embodiment of the present disclosure. The blood pump 510 according to the fifth embodiment differs from the blood pump 410 according to the fourth embodiment in the configuration of the impeller 518, the second bearing member 548 and the purge arrangement 552.

[0084] The configuration of the second bearing member 548 is similar to the configuration of the second bearing member 248 according to the second embodiment. The second bearing member 548 is disposed in the area of the blood flow inlet 14 and directly supports the impeller 518. As in the other embodiments, the second bearing member 548 is configured as a slide bearing configured to support radial loads of the impeller 518. During operation of the blood pump 510, the second bearing member 548 is purged by blood sucked into the pump housing 12 via the blood flow inlet 14 due to rotation of the impeller 518.

[0085] In this embodiment, the first purge channel 554 is provided on the impeller 518. As shown in Figs. 14 and 15, the first purge channel 554 is provided as at least one recess disposed between the two blades of the impeller 518 at the axial end of the impeller 518 opposite to the second bearing member 548. In this particular embodiment, the first purge channel 554 is composed of two recesses evenly distributed about the impeller 518. The first purge channel 554 is shaped and configured to convey a portion of blood flowing along the blood flow passage 20 during operation of the blood pump 510 to the second purge channel 556.

[0086] In this embodiment, the purge arrangement further comprises a fourth purge channel 560 and a fifth purge channel 561 . The pump housing 12 comprises a plurality of purge openings 564 on its cylindrical portion 66. The purge openings 564 are evenly distributed about the outer peripheral surface of the cylindrical portion 66 of the pump housing 12. In this particular embodiment, the blood pump 510 comprises a total of six purge openings 564. The purge openings 564 are provided radially outwardly of the first rotor element 426.

[0087] The fourth purge channel 560 is disposed between the second stator element 428 and the first rotor element 426. In other words, the fourth purge channel 560 virtually corresponds to the second magnetic gap 538. The fourth purge channel 560 connects the third purge channel 558 and the purge openings 564. The fifth purge channel 561 is disposed between the first stator element 424 and the first rotor element 426. In other words, the fifth purge channel 561 virtually corresponds to the first magnetic gap 536. The fifth purge channel 561 connects the third purge channel 558 and the purge openings 564.

[0088] For purging the blood pump 510, blood is conveyed along the first purge channel 554 due to rotation of the impeller 518. The blood then enters the second purge channel 556 and flows towards the first bearing member 440 along the second purge channel 556 between the second stator element 428 and the shaft 430. The blood then enters the third purge channel 558 and flows along the fourth purge channel 560 and the fifth purge channel 561 and exits the blood pump housing 12 through the purge openings 564. Thus, the first bearing member 440 is purged.

[0089] To facilitate the blood flow for purging, the axial end face of the impeller 518 facing the drive unit 422 can be provided with secondary pump elements e.g., blades or protrusions generating the blood flow for purging. Alternatively or in addition, secondary pump elements may also be provided on one or both axial end faces of the first rotor element 426 facing the first stator element 424 and the second stator element 428 respectively.

[0090] EXEMPLARY IMPLEMENTATIONS

[0091] As already described, the technology described herein may be implemented in various ways. In that regard, the foregoing disclosure is intended to include, but not be limited to, the systems, methods, and combinations and subcombinations thereof that are set forth in the following exemplary implementations. Preferred embodiments are described in the following paragraphs:

[0092] A1 Blood pump comprising: a pump housing having at least one blood flow inlet and at least one blood flow outlet, a pump element disposed in the pump housing so as to be rotatable about an axis of rotation for conveying blood from the blood flow inlet to the blood flow outlet along a blood flow passage, and a drive unit for rotating the pump element.

[0093] A2 Blood pump according to paragraph A1 , wherein the drive unit comprises a first drive unit element and a second drive unit element

[0094] A3 Blood pump according to paragraph A2, wherein the drive unit comprises a third drive unit element, wherein the second drive unit element is disposed between the first drive unit element and the third drive unit element in an axial direction along the axis of rotation.

[0095] A4 Blood pump according to paragraph A3, wherein the first drive unit element and the third drive unit element are of a first type, and wherein the second drive unit element is of a second type, A5 Blood pump according to paragraph A4, wherein the second type is different from the first type.

[0096] A6 Blood pump according to any one of the preceding paragraphs A3 to A5, wherein the first drive unit element of the first type is a first rotor element, the third drive unit element of the first type is a second rotor element and the second drive unit element of the second type is a first stator element.

[0097] A7 Blood pump according to paragraph A6, wherein the first rotor element and the second rotor element are connected to the pump element so as to rotate together with the pump element,

[0098] A8 Blood pump according to paragraph A6 or A7, wherein the first stator element is fixed within the pump housing and disposed about the axis of rotation.

[0099] A9 Blood pump according to any one of the preceding paragraphs A6 to A8, wherein the pump element comprises the second rotor element.

[0100] A10 Blood pump according to any one of the preceding paragraphs A1 to A9, wherein the blood pump further comprises a shaft coaxial to the axis of rotation.

[0101] A11 Blood pump according to paragraph A10, wherein the shaft comprises a first axial end and a second axial end and extends through the first stator element.

[0102] A12 Blood pump according to paragraph A10 or A11 , wherein the first rotor element is attached to the shaft in the area of the first axial end.

[0103] A13 Blood pump according to any one of the preceding paragraphs A10 to A12, wherein the pump element is attached to the second axial end of the shaft.

[0104] A14 Blood pump according to any one of the preceding paragraphs A10 to A13, wherein the second rotor element is attached to the shaft between the first axial end of the shaft and the second axial end of the shaft.

[0105] A15 Blood pump according to any one of the preceding paragraphs A3 to A5, wherein the first drive unit element of the first type is a first stator element, the third drive unit element of the first type is a second stator element and the second drive unit element of the second type is a first rotor element.

[0106] A16 Blood pump according to paragraph A15, wherein the first rotor element is connected to the pump element so as to rotate together with the pump element, A17 Blood pump according to paragraph A15 or A16, wherein the first stator element and the second stator element are fixed within the pump housing and disposed about the axis of rotation.

[0107] A18 Blood pump according to any one of the preceding paragraphs A1 to A5 or A15 to A17 wherein the blood pump further comprises a shaft coaxial to the axis of rotation.

[0108] A19 Blood pump according to paragraph A18, wherein the shaft comprises a first axial end and a second axial end

[0109] A20 Blood pump according to paragraph A18 or A19, wherein the shaft extends through the second stator element.

[0110] A21 Blood pump according to any one of the preceding paragraphs A18 to A20, wherein the first rotor element is attached to the shaft in the area of the first axial end.

[0111] A22 Blood pump according to any one of the preceding paragraphs A18 to A21 , wherein the pump element is attached to the second axial end of the shaft.

[0112] A23 Blood pump according to any one of the preceding paragraphs A10 to A14 or A18 to A22, wherein the blood pump further comprises a first bearing member, wherein the first axial end of the shaft is rotatably supported by the first bearing member.

[0113] A24 Blood pump according to paragraph A24, wherein the first bearing member is a pivot bearing.

[0114] A25 Blood pump according to paragraph A23 or A24, wherein the first bearing member comprises a first support surface

[0115] A26 Blood pump according to any one of the preceding paragraphs A23 to A25, wherein the first bearing member comprise a ball

[0116] A27 Blood pump according to any one of the preceding paragraphs A23 to A26, wherein the shaft comprises a second support surface at the first axial end of the shaft.

[0117] A28 Blood pump according to paragraph A27, wherein the ball is disposed between the first support surface and the second support surface.

[0118] A29 Blood pump according to any one of the preceding paragraphs A1 to A29, wherein the blood pump further comprises a second bearing member. A30 Blood pump according to paragraph A29, wherein the second bearing member supports the shaft and is preferably disposed between the pump element and the drive unit in the axial direction.

[0119] A31 Blood pump according to paragraph A29, wherein the second bearing member supports the pump element.

[0120] A32 Blood pump according to paragraphs A6 to A14 or A23 to A31 , wherein the blood pump comprises a purge arrangement.

[0121] A33 Blood pump according to paragraph A32, wherein the purge arrangement comprises a first purge channel connected to the blood flow passage.

[0122] A34 Blood pump according to paragraph A32 or A33, wherein the purge arrangement comprises a second purge channel connected to the first purge channel.

[0123] A35 Blood pump according to paragraph A34, wherein the second purge channel is disposed at least between the second rotor element and the first stator element.

[0124] A36 Blood pump according to any one of the preceding paragraphs A32 or A35, wherein the purge arrangement comprises a third purge channel.

[0125] A37 Blood pump according to paragraph A36, wherein the third purge channel is at least connected to the second purge channel

[0126] A38 Blood pump according to paragraph A36 or A37, wherein the third purge channel axially extends through the first stator element.

[0127] A39 Blood pump according to any one of the preceding paragraphs A32 to A38, wherein the purge arrangement comprises a fourth purge channel

[0128] A40 Blood pump according to paragraph A39, wherein the fourth purge channel is at least partially disposed radially inwardly of the first rotor element.

[0129] A41 Blood pump according to paragraph A39 or A40, wherein the fourth purge channel is at least connected to the third purge channel.

[0130] A42 Blood pump according to any one of the preceding paragraphs A32 to A41 , wherein the purge arrangement comprises a fifth purge channel.

[0131] A43 Blood pump according to paragraph A42, wherein the fifth purge channel is connected to the third purge channel A44 Blood pump according to paragraph A42 or A43, wherein the fifth purge channel is at least partially disposed between the first stator element and the first rotor element.

[0132] A45 Blood pump according to any one the preceding paragraphs A32 to A44, wherein the pump housing comprises at least one purge opening

[0133] A46 Blood pump according to paragraph A45, wherein the fourth purge channel is connected to the at least one purge opening.

[0134] A47 Blood pump according to any one of the preceding paragraphs A15 to A31 , wherein the blood pump comprises a purge arrangement.

[0135] A48 Blood pump according to paragraph A47, wherein the purge arrangement comprises a first purge channel.

[0136] A49 Blood pump according to paragraph A48, wherein the first purge channel is connected to the blood flow passage.

[0137] A50 Blood pump according to any one of the preceding paragraphs A47 to A49, wherein the purge arrangement comprises a second purge channel.

[0138] A51 Blood pump according to paragraph A50, wherein the second purge channel is connected to the first purge channel.

[0139] A52 Blood pump according to paragraph A50 or A51 , wherein the second purge channel axially extends through the second stator element.

[0140] A53 Blood pump according to any one of the preceding paragraphs A47 to A52, wherein the purge arrangement comprises a third purge channel.

[0141] A54 Blood pump according to paragraph A53, wherein the third purge channel is at least partially disposed radially inwardly of the first rotor element.

[0142] A55 Blood pump according to paragraphs A53 or A54, wherein the second purge channel is connected to the third purge channel.

[0143] A56 Blood pump according to any one of the preceding paragraphs A47 to A55, wherein the pump housing comprises at least one purge opening

[0144] A57 Blood pump according to paragraph any one of the preceding paragraphs A47 to A56, wherein the purge arrangement comprises a fourth purge channel. A58 Blood pump according to paragraph A57, wherein the fourth purge channel is disposed between the first rotor element and the second stator element.

[0145] A59 Blood pump according to paragraph A57 or A58, wherein the fourth purge channel is at least connected to the third purge channel

[0146] A60 Blood pump according to any one of the preceding paragraphs A57 to A59, wherein the fourth purge channel is connected to the at least one purge opening.

[0147] A61 Blood pump according to any one of the preceding paragraphs A47 to A60, wherein the purge arrangement comprises a fifth purge channel.

[0148] A62 Blood pump according to paragraph A61 , wherein the fifth purge channel is disposed between the first rotor element and the first stator element.

[0149] A63 Blood pump according to paragraph A62, wherein the fifth purge channel is at least connected to the at least one purge opening.

[0150] A64 Blood pump according to any one of the preceding paragraphs A61 to A63, wherein the fifth purge channel is connected to the third purge channel.

[0151] A65 Blood pump according to any one of the preceding paragraphs A1 to A64, wherein the pump element comprises at least one first opening.

[0152] A66 Blood pump according to any one of the preceding paragraphs A1 to A65, wherein the pump element comprise at least one second opening, wherein the second opening is coaxial with the axis of rotation

[0153] A67 Blood pump according to paragraph A65 and A66, wherein the first purge channel extends between the at least one first opening and the second opening.

[0154] A68 Blood pump according to any one of the preceding paragraphs A32 to A67, wherein the blood pump housing comprises a purge fluid inlet connected to the purge arrangement.

[0155] A69 Blood pump according to paragraph A68, wherein the purge fluid inlet penetrates the first support surface of the first bearing member.

[0156] A70 Blood pump according to any one of the preceding paragraphs A1 to A69, wherein a first magnetic gap is formed between the first drive unit element and the second drive unit element. A71 Blood pump according to any one of the preceding paragraphs A1 to A70, wherein a second magnetic gap is formed between the second drive unit element and the third drive unit element.

[0157] A72 Blood pump according to paragraph A70 and A71 , wherein an axial extension of the first magnetic gap and an axial extension of the second magnetic gap are dimensioned to cancel out axial force components established by attractive magnetic forces between the first drive unit element and the second drive unit element and between the second drive unit element and the third drive unit element.

[0158] A73 Blood pump according any one of the preceding paragraphs A1 to A72, wherein a first magnetic gap is provided between the first drive unit element and the second drive unit element.

[0159] A74 Blood pump according to any one of the preceding paragraphs A1 to A73, wherein a second magnetic gap is provided between the third drive unit element and the second drive unit element.

[0160] A75 Blood pump according to paragraph A73 or A74, wherein an axial extension of the first magnetic gap and an axial extension of the second magnetic gap are dimensioned so that axial force components established between the first drive unit element and the second drive unit element and the third drive unit element and the second drive unit element and an axial force component induced by rotation of the pump element during operation of the blood pump cancel each other out.

[0161] A76 Blood pump according to paragraph A75, wherein the axial extension of the first magnetic gap is different from the axial extension of the second magnetic gap.

[0162] A77 Blood pump according to any one of the preceding paragraphs A6 to A76, wherein the first rotor element has a magnetic field strength different from a magnetic field strength of the second rotor element.

[0163] A78 Blood pump according to any one of the preceding paragraphs A15 to A76, wherein the first stator element has a cross-sectional area different from a cross-sectional area of the second stator element.

[0164] A79 Blood pump according to any one of the preceding paragraphs A1 to A78, wherein the drive unit comprises a total of exactly three drive unit elements.

[0165] As utilized herein, the terms “approximately”, “about”, “substantially” and similar terms are intended to have a broad meaning in harmony with the common and accepted usage by those of ordinary skill in the art to which the subject matter of this disclosure pertains. It should be understood by those of skill in the art who review this disclosure that these terms are intended to allow a description of certain features described without restricting the scope of these features to the precise numerical ranges provided. Accordingly, these terms should be interpreted as indicating that insubstantial or inconsequential modifications or alterations of the subject matter described and are considered to be within the scope of the disclosure. The terms „at least partially” or “partially” as used herein mean both partial and entirely or complete respectively. Furthermore, terms like “first” or “second” do not imply a specific order, but are only intended to allow for linguistic differentiation between the elements.

[0166] List of reference signs

[0167] 10, 210, 310,410, 510 blood pump

[0168] 12 pump housing

[0169] 14 blood flow inlet

[0170] 16 blood flow outlet

[0171] 18, 218, 318, 518 pump element / impeller

[0172] 20 blood flow passage

[0173] 22, 222, 322, 422 drive unit

[0174] 24 first drive unit element / first rotor element

[0175] 26 second drive unit element / first stator element

[0176] 28, 228, 328 third drive unit element / second rotor element

[0177] 30, 430 shaft

[0178] 32, 432 first axial end of shaft

[0179] 34, 434 second axial end of shaft

[0180] 36, 436 first magnetic gap

[0181] 38, 438 second magnetic gap

[0182] 40, 440 first bearing member

[0183] 42, 442 first support surface

[0184] 44, 444 ball

[0185] 46, 446 second support surface

[0186] 48, 248, 448, 548 second bearing member

[0187] 50 tapering portion

[0188] 52, 252, 352, 452, 552 purge arrangement

[0189] 54, 254, 354, 454, 554 first purge channel

[0190] 56, 456, 556 second purge channel

[0191] 58, 458, 558 third purge channel

[0192] 60, 560 fourth purge channel

[0193] 62, 462 purge fluid inlet

[0194] 66 cylindrical portion

[0195] 68 reduced portion

[0196] 70 attachment portion

[0197] 72 blade

[0198] 261 , 561 fifth purge channel

[0199] 264, 564 purge opening

[0200] 374 first opening

[0201] 376 second opening 424 first drive unit element / first stator element

[0202] 426 second drive unit element / first rotor element

[0203] 428 third drive unit element / second stator element

[0204] 478 housing member

[0205] AR axis of rotation

Claims

CLAIMS1 . Blood pump (10, 210, 310, 410, 510) comprising: a pump housing (12) having at least one blood flow inlet (14) and at least one blood flow outlet (16), a pump element (18, 218, 318, 518) disposed in the pump housing (12) so as to be rotatable about an axis of rotation (AR) for conveying blood from the blood flow inlet (14) to the blood flow outlet (16) along a blood flow passage (20), and a drive unit (22, 222, 322, 422) for rotating the pump element (18, 218, 318, 518), the drive unit (22, 222, 322, 422) comprising a first drive unit element (24, 424), a second drive unit element (26, 426) and a third drive unit element (28, 228, 428), wherein the second drive unit element (26, 426) is disposed between the first drive unit element (24, 424) and the third drive unit element (28, 228, 428) in an axial direction along the axis of rotation (AR), wherein the first drive unit element (24, 424) and the third drive unit element (28, 228, ,328, 428) are of a first type, and wherein the second drive unit (26, 426) element is of a second type, wherein the second type is different from the first type.

2. Blood pump (10, 210, 210, 310, 410, 510) according to claim 1 , wherein a first magnetic gap (36, 436) is provided between the first drive unit element (24, 424) and the second drive unit element (26, 426) and a second magnetic gap (38, 438) is provided between the third drive unit element (28, 228, 428) and the second drive unit element (26, 426), wherein an axial extension of the first magnetic gap (36, 436) and an axial extension of the second magnetic gap (38, 438) are dimensioned so that axial force components established between the first drive unit element (24, 424) and the second drive unit element (26, 426) and the third drive unit element (28, 228, 428) and the second drive unit (26, 426) element and an axial force component generated by hydraulic thrust of the pump element (18, 218, 318, 518) during operation of the blood pump (10, 210, 310, 410, 510) cancel each other out.

3. Blood pump (10, 210, 210, 310, 410, 510) according to claim 2, wherein the axial extension of the first magnetic gap (36, 436) and the axial extension of the second magnetic gap (38, 438) are different.

4. Blood pump (10, 210, 310) according to any one of the preceding claims,wherein the first drive unit element (24) of the first type is a first rotor element, the third drive unit element (28, 228, 328) of the first type is a second rotor element and the second drive unit element (26) of the second type is a first stator element, wherein the first rotor element (24) and the second rotor element (28, 228, 328) are connected to the pump element (18, 218, 318) so as to rotate together with the pump element (18, 218, 318), wherein the first stator element (26) is fixed within the pump housing (12) and disposed about the axis of rotation (AR).

5. Blood pump (10, 210, 310) according to claim 4, wherein a magnetic field strength of the first rotor element (24) is different from a magnetic field strength of the second rotor element (28, 228, 328).

6. Blood pump (210, 310) according to claim 4 or 5, wherein the pump element (218, 318) comprises the second rotor element (228, 328).

7. Blood pump (10, 210, 310) according any one of the preceding claims 4 to 6, wherein the blood pump (10, 210, 310) further comprises a shaft (30) coaxial to the axis of rotation (AR), wherein the shaft (30) comprises a first axial end (32) and a second axial end (34) and extends through the first stator element (26), wherein the first rotor element (24) is attached to the shaft (30) preferably in the area of the first axial end (32), and wherein the pump element (18, 218, 318) is attached to the second axial end (34) of the shaft (30).

8. Blood pump (10, 210, 310,) according to claim 7, wherein the second rotor element (28) is attached to the shaft (30) between the first axial end (32) of the shaft (30) and the second axial end (34) of the shaft (30).

9. Blood pump (410, 510) according to one of the preceding claims 1 to 3, wherein the first drive unit element (424) of the first type is a first stator element, the third drive unit element (428) of the first type is a second stator element and the second drive unit element (426) of the second type is a first rotor element, wherein the first rotor element (426) is connected to the pump element (418, 518) so as to rotate together with the pump element (418, 518), wherein the first stator element (424) and the second stator element (428) are fixed within the pump housing (12) and disposed about the axis of rotation (AR).

10. Blood pump (410, 510) according to claim 9, wherein a cross-sectional area of the first stator element (424) is different from a cross- sectional area of the second stator element (428).11 . Blood pump (410, 510) according to claim 9 or 10, wherein the blood pump (410, 510) further comprises a shaft (430) coaxial to the axis of rotation (AR), wherein the shaft (430) comprises a first axial end (432) and a second axial end (434) and extends through the second stator element (428), wherein the first rotor element (426) is preferably attached to the shaft (430) in the area of the first axial end (432), and wherein the pump element (418, 518) is preferably attached to the second axial end (434) of the shaft (430).

12. Blood pump (10, 210, 310, 410, 510) according to any one of the preceding claims 7, 8 or 11 , wherein the blood pump (10, 210, 310, 410, 510) further comprises a first bearing member (40, 444), wherein the first axial end (32, 432) of the shaft (30, 430) is rotatably supported by the first bearing member (40, 440), wherein the first bearing member (40, 444) preferably is a pivot bearing, wherein the first bearing member (40, 440) preferably comprises a first support surface (42, 442) and a ball (44, 444), wherein the shaft (30, 430) preferably comprises a second support surface (46, 446) at the first axial end (32, 432) of the shaft (30, 430), wherein the ball (44, 444) is preferably disposed between the first support surface (42, 442) and the second support surface (46, 446).

13. Blood pump (10, 210, 310,410, 510) according to any one of the preceding claims 7, 8, 11 or 12, wherein the blood pump (10, 210, 310,410, 510) further comprises a second bearing member (48, 248, 448, 548), wherein the second bearing member (48, 448) supports the shaft (30, 430) and is preferably disposed between the pump element (18) and the drive unit (22, 422) in the axial direction, or wherein the second bearing member (248, 548) supports the pump element.

14. Blood pump (10, 210, 310) according to claim 4 or any one of claims 5, 6, 7, 8, 12 or 13 when depending from claim 4, wherein the blood pump (10, 210, 310) comprises a purge arrangement (52, 252, 352), wherein the purge arrangement (52, 252, 352) comprises a first purge channel (54, 254, 354) connected to the blood flow passage (20),wherein the purge arrangement (52, 252, 352) comprises a second purge channel (56) connected to the first purge channel (52, 252, 352) and disposed at least between the second rotor element (28, 228, 328) and the first stator element (26), wherein the purge arrangement (52, 252, 352) comprises a third purge (58) channel at least connected to the second purge channel (56) and axially extending through the first stator element (26), wherein the purge arrangement (52, 252, 352) comprises a fourth purge channel (60) at least partially disposed radially inwardly of the first rotor element (24) and at least connected to the third purge channel (58), wherein the purge arrangement (252) preferably comprises a fifth purge channel (261) connected to the third purge channel (58) and at least partially disposed between the first stator element (26) and the first rotor element (24); and wherein the pump housing (12) preferably comprises at least one purge opening (264), wherein the fourth purge channel (60) is preferably connected to the at least one purge opening (264).

15. Blood pump (410, 510) according to claim 9 or any one of the preceding claims 11 or 12 when depending from claim 9, wherein the blood pump (410, 510) comprises a purge arrangement (452, 552) wherein the purge arrangement (452, 552) comprises a first purge channel (454, 554) connected to the blood flow passage (20), wherein the purge arrangement (452, 552) comprises a second purge channel (546, 556) connected to the first purge channel (454, 554) and axially extending through the second stator element (428), wherein the purge arrangement (452, 552) comprises a third purge channel (458, 558) at least partially disposed radially inwardly of the first rotor element (426), and wherein the second purge channel (456, 556) is connected to the third purge channel (548, 558).

16. Blood pump (510) according to claim 15, wherein the pump housing (12) comprises at least one purge opening (564), wherein the purge arrangement (552) comprises a fourth purge channel (560) disposed between the first rotor element (426) and the second stator element (428), wherein the fourth purge channel (560) is at least connected to the third purge channel (558) and the purge opening (564).

17. Blood pump (510) according to claim 16,wherein the purge arrangement (552) comprises a fifth purge channel (561) disposed between the first rotor element (426) and the first stator element (424), wherein the fifth purge channel (561) is at least connected to the purge opening (564) and the third purge channel (558).

18. Blood pump (310) according to any one of the preceding claims 14 to 17, wherein the pump element (318) comprises at least one first opening (374) and at least one second opening (376), wherein the second opening (376) is coaxial with the axis of rotation (AR), and wherein the first purge channel (354) extends between the at least one first opening (374) and the second opening (376).

19. Blood pump (10, 410) according to any one of the preceding claims 14 to 18, wherein the blood pump housing (12) comprises a purge fluid inlet (62, 462) connected to the purge arrangement (52, 452).

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