Drive mechanism and blood pump thereof

Abstract

The application is a driving mechanism and blood pump for preventing the rotation shaft from being stuck and preventing current leakage, wherein a metal inner sleeve is arranged on the inner ring of the hollow cup winding, and the metal inner sleeve is filled with the epoxy resin shell as an integral structure, so as to enhance the strength of the epoxy resin shell and prevent the epoxy resin shell from being deformed or broken; the fixing mode of the bearing is changed to be directly welded with the metal inner sleeve, so that the connection is reliable, and the bearing can reliably support the rotation shaft in the axial direction and the radial direction, so as to prevent the sticking and stopping phenomenon; three metal sheets are led out on the metal inner sleeve and are directly welded with the external cable, so that the PCB board does not need to be additionally arranged, and the process is simple; the bearing protection cover is arranged outside the proximal bearing, so as to isolate the liquid path environment and the circuit environment and ensure the safe operation of the motor.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically to a drive mechanism and its blood pump. Background Technology

[0002] Blood pumps support cardiac function, providing hemodynamic support for cardiogenic shock or acute heart failure in short-term (days or weeks) or long-term (weeks or months) applications. Various types of blood pumps are known, such as axial flow, centrifugal, or hybrid pumps. Their structure includes a pump housing and an impeller, with an electric motor housed within the housing cavity. The motor's rotor, a permanent magnet, is mounted on a shaft and coupled to the impeller. A coil winding is mounted on the stator and coaxially arranged with the rotor. When current is applied, an interacting electromagnetic field is formed between the winding and the permanent magnet, generating axial and / or radial forces that cause the rotor and impeller to rotate synchronously in a circumferential direction, pumping blood from the ventricles into the arteries to achieve blood flow. The stator surface is encapsulated with epoxy resin to form a protective shell for the motor, isolating the motor from the external environment. The bearings are directly encapsulated in the epoxy resin shell, meaning that the bearings are supported solely by the epoxy resin shell. During the high-speed rotation of the rotor, the bearings are subjected to great forces, but the epoxy resin shell is relatively thin and slightly insufficient. If the epoxy resin shell deforms or breaks, the bearings will not be able to provide reliable support for the shaft, causing the shaft to tilt and resulting in the motor seizing up and stopping. Summary of the Invention

[0003] One object of the present invention is to provide a drive mechanism that prevents the shaft from jamming and prevents current leakage.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a driving mechanism, including a housing and a rotor assembly and a stator assembly coaxially arranged inside the housing. The stator assembly includes an inner sleeve, an outer sleeve, and a hollow cup winding located between the inner sleeve and the outer sleeve. The inner sleeve is made of metal. At least one bearing at each end of the rotor assembly's shaft is welded and fixed to the inner wall of the inner sleeve.

[0005] The inner sleeve is made of stainless steel with a thickness of 0.1mm-0.2mm, and an insulating and anti-corrosion coating is attached to the inner circumferential wall of the stainless steel sleeve.

[0006] The inner sleeve has a metal sheet extending from its proximal end, and the terminals of the hollow cup winding and the external cables are all welded to the metal sheet.

[0007] The metal sheets are evenly and spaced three times on the near-end outer wall of the inner sleeve, and the three metal sheets extend from the outer wall of the bearing toward the near end.

[0008] The bearing includes a proximal bearing and a distal bearing. The proximal bearing is covered by a bearing protective cover. The bearing protective cover includes a first cover and a second cover. The openings of the first cover and the second cover interlock to form a cavity for accommodating the proximal bearing. The outer wall of the first cover has an axial groove for accommodating a metal sheet. The outer wall of the second cover has an axial cable routing groove for accommodating external cables. The proximal end of the second cover extends a connecting pipe for connecting to a cleaning pipeline. The cable routing groove extends to the wall of the connecting pipe.

[0009] The wiring grooves and recesses are arranged in a one-to-one correspondence to form a connecting groove. There are 3 sets of connecting grooves, where the cross-section of the recess is U-shaped and the cross-section of the wiring groove is semi-circular.

[0010] The first cover and the second cover are bonded together with glue. The far end face of the first cover abuts against the near end face of the inner sleeve, and the joint is coated with sealant to form a sealed fit.

[0011] The proximal bearing is a ball bearing, and the distal bearing is a sliding bearing. The stepped surface of the inner cavity of the housing abuts against the outer ring of the ball bearing and is fixedly connected by adhesive. The gap between the inner and outer rings of the ball bearing, the gap between the inner sleeve and the rotor assembly, and the gap between the sliding bearing and the shaft constitute the cleaning passage.

[0012] The bearing protective cover is made of plastic.

[0013] The gap between the inner sleeve and the permanent magnet of the rotor assembly is 0.1mm-0.5mm.

[0014] The outer sleeve is made of ferritic alloy material with a thickness of 0.2mm-0.3mm.

[0015] The housing is a protective layer formed by epoxy resin potting on the surface of the stator assembly and between the components to isolate the motor from the external environment.

[0016] One object of the present invention is to provide a blood pump that prevents the shaft from jamming and prevents current leakage.

[0017] To achieve the above objectives, the technical solution adopted by the present invention is as follows: a blood pump, a drive mechanism, wherein the distal end of the rotating shaft protrudes to the outside of the housing and is fixedly connected to the impeller, the impeller is disposed inside the sleeve, and the drive device drives the impeller to rotate and draws blood in from the sleeve inlet and pumps it out from the sleeve outlet.

[0018] The above solution has at least the following beneficial effects: A metal inner sleeve is installed in the inner ring of the hollow cup winding. The metal inner sleeve and the epoxy resin shell are encapsulated as an integral structure, which enhances the strength of the epoxy resin shell and prevents the epoxy resin shell from deforming or breaking. The bearing fixing method has been changed to direct welding to the metal inner sleeve, which ensures a reliable connection. The bearing can provide reliable support to the shaft in both the axial and radial directions, eliminating jamming and stoppage. Three metal plates are led out from the inner metal sleeve and directly soldered to the external cables, so there is no need to set up an additional PCB board, and the process is simple; A bearing protective cover is installed outside the near-end bearing to isolate the liquid circuit environment and the electrical circuit environment, ensuring the safe operation of the motor. The hybrid bearing support scheme ensures that the shaft rotates in the center, which can increase the perfusion pressure of the flushing fluid at that point and reduce the risk of blood flowing into the drive structure and causing thrombosis. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the blood pump in Example 1; Figure 2 This is a cross-sectional view of the blood pump in Example 2; Figure 3 This is a cross-sectional view of the blood pump in Example 3; Figure 4 This is a cross-sectional view of the blood pump in Example 4; Figure 5 This is a cross-sectional view of the drive mechanism; Figure 6 This is a three-dimensional view of the second enclosure; Figure 7 This is a three-dimensional view of the first enclosure. Figure 8 This is a three-dimensional view of the inner sleeve; Figure 9 for Figure 4 Enlarged schematic diagram of the near-end bearing; Figure 10 for Figure 4 Enlarged schematic diagram of the bearing at the mid-to-far end. Detailed Implementation

[0020] To facilitate understanding, let's first define the orientation: "proximal" or "proximal" refers to the side closer to the operator / doctor, while "distal" or "distal" refers to the side farther from the operator / doctor, i.e., the side closer to the heart. Below, we'll combine these definitions... Figures 1-10 The invention will be discussed in further detail.

[0021] A drive mechanism includes a housing 10 and a rotor assembly 20 and a stator assembly 30 coaxially arranged within the housing 10. The stator assembly 30 includes an inner sleeve 31 and an outer sleeve 32 coaxially sleeved together, and a hollow cup winding 33 located between the inner sleeve 31 and the outer sleeve 32. The inner sleeve 31 is made of metal. At least one bearing 40 at each end of the shaft 21 of the rotor assembly 20 is welded and fixed to the inner wall of the inner sleeve 31.

[0022] In the existing technology, the bearing is directly encapsulated in an epoxy resin housing. That is to say, the bearing is supported only by the epoxy resin housing. During the high-speed rotation of the rotor, the bearing is subjected to great forces, but the epoxy resin housing is thin and slightly insufficient. If the epoxy resin housing deforms or breaks, the bearing will not be able to provide reliable support for the shaft, the shaft will tilt, and the motor will seize up or stop.

[0023] This invention addresses the aforementioned problems by incorporating a metal inner sleeve 31 within the inner ring of the hollow cup winding 33. This metal inner sleeve 31 is integrally encapsulated with the epoxy resin outer shell, enhancing its strength and preventing deformation or breakage. Furthermore, the bearing 40 is now directly welded to the metal inner sleeve 31, ensuring a reliable connection. The bearing 40 provides reliable support to the shaft 21 both axially and radially, preventing jamming and stalling.

[0024] Preferably, the inner sleeve 31 is made of stainless steel with a thickness of 0.1mm-0.2mm. Stainless steel has reliable rigidity and good conductivity, which can provide reliable support for the bearing 40 and prevent the bearing 40 from jamming and the drive mechanism from stopping. An insulating and anti-corrosion coating is attached to the inner circumferential wall of the stainless steel sleeve. This insulating and anti-corrosion coating can be added separately or it can be a thin layer of epoxy resin that is formed together with the epoxy resin shell during potting.

[0025] The most common connection method for external cable A in the industry is as follows: PCB pads are soldered to the end of the bearing or the outer end cover. The terminals of the hollow cup winding 33 are led outwards and soldered to one side of the three copper plates of the PCB pads. The three terminals of external cable A are soldered to the other side of the three copper plates. However, the bonding of the PCB pads is relatively complicated. In this application, since the inner sleeve 31 is made of conductive material, a metal plate 34 is provided near the end of the inner sleeve 31. The terminals of the hollow cup winding 33 and external cable A are soldered to the metal plate 34. This eliminates the need for an additional PCB soldering board, resulting in a simple structure and easy soldering operation.

[0026] For a 3-phase motor, such as Figure 8 As shown, three metal sheets 34 are evenly and spaced apart on the near-end outer wall of the inner sleeve 31, and the three metal sheets 34 extend from the outer wall of the bearing 40 toward the near end and are welded to the external cable A.

[0027] Bearing 40 includes a proximal bearing 40a and a distal bearing 40b. Since the proximal end of the hollow cup winding 33 needs to be electrically connected to the external cable A, and considering the need to prevent blood from seeping into the blood pump, a cleaning fluid (such as heparin, glucose solution, etc.) can be extended from outside into the blood pump and flow out from the impeller side to push out blood and prevent blood from entering the blood pump or clotting into a blood clot. The inlet of the cleaning fluid is generally near the connection point between the external cable A and the hollow cup winding 33. To prevent the cleaning fluid from contacting the electrical connection point and damaging the blood pump function, the proximal bearing 40a is covered with a bearing protective cover 50. The bearing protective cover 50 is generally a shell-shaped cover with an opening facing the distal side. The inner cavity of the cover forms a chamber 51 for accommodating the proximal bearing 40a. The outer wall of the cover has an axially formed groove 511 for accommodating the metal sheet 34. The proximal end of the cover extends a connecting pipe 53 for connecting to the cleaning pipeline. The wall of the connecting pipe 53 has an axially formed cable groove 521. By setting a bearing protective cover 50 to house the near-end bearing 40a within its inner cavity and connecting a cleaning pipe 70 into the cover, normal flow of fluid in the cleaning pipe is ensured, while preventing contact between the internal fluid and the external circuit structure, effectively guaranteeing the normal operation of the blood pump. The terminals of the hollow cup winding 33 are welded to the inner sleeve 31 or directly to the metal sheet 34, which is housed in the groove 511. The external cable A passes through the wiring groove 521 and is then welded to the metal sheet 34, thereby achieving electrical connection between the external cable A and the hollow cup winding 33.

[0028] Furthermore, the wiring grooves 521 and recesses 511 are arranged in a one-to-one correspondence to form a connecting groove. There are a total of 3 sets of connecting grooves. The cross-section of the recess 511 is U-shaped, and the cross-section of the wiring groove 521 is semi-circular. For a three-phase motor, the hollow cup winding 33 has three terminals, and the external cable A also has three terminals. Therefore, a total of 3 sets of connecting grooves are set here. The cross-section of each groove also matches the cross-section of the component accommodated by each groove. After welding is completed, epoxy resin is used for potting to form the housing 10.

[0029] To isolate the liquid environment from the electrical environment, the first cover 51 and the second cover 52 are bonded together with adhesive. The distal end face of the first cover 51 abuts against the proximal end face of the inner sleeve 31, and the connection is coated with sealant to form a sealed fit. This prevents the cleaning fluid in the cleaning path from entering the electrical environment, effectively preventing current leakage. Simultaneously, the sealant is used for bonding and curing. When applied to and operated in a blood pump, the high-speed operation of the pump generates heat due to blood flow. Under the effect of thermal expansion, the gap structure where the sealant is located provides a buffer space for thermal expansion.

[0030] Preferably, the proximal bearing 40a is a ball bearing, and the distal bearing 40b is a sliding bearing. The ball bearing includes an inner ring 41, an outer ring 42, and balls 43 between them. The structure is a common structure and will not be described in detail here. Through the hybrid bearing support scheme, where the sliding bearing and the ball bearing provide radial support, the rotating shaft 21 can achieve stable radial rotation. Furthermore, a gap is formed between the shaft hole of the sliding bearing and the rotating shaft 21, allowing cleaning fluid to pass through. The sliding bearing and the rotating shaft 21 are separated by the cleaning fluid and do not come into direct contact. When the rotating shaft 21 experiences radial displacement, it will be subjected to a radial restoring force provided by the squeezed fluid, ensuring that the rotating shaft 21 rotates in a centered position. The existence of this gap and the self-aligning nature of the sliding bearing's diaphragm avoid the problems of difficult assembly of the bearing and the rotating shaft 21, and the difficulty of coaxial alignment of the two rolling bearings, which exist in the dual rolling bearing scheme. The sliding bearing in this application is an independent part, which is machined and formed separately and directly welded to the inner wall of the inner sleeve 31, making the connection reliable. Moreover, the blood pump uses a sliding bearing at the end near the impeller 60. Since the sliding bearing has a smaller axial clearance than the ball bearing, it can increase the perfusion pressure of the flushing fluid at that point and reduce the risk of blood flowing into the drive structure and causing thrombosis.

[0031] The stepped surface of the inner cavity of the housing abuts against the outer ring 42 of the ball bearing and is fixedly connected by adhesive. The outer peripheral wall and end face of the outer ring 42 are also bonded to the inner cavity of the housing by adhesive. The contact area is large and there are limiting structures at both ends, so the connection is reliable.

[0032] As mentioned above, to prevent blood from entering the bearing and forming a thrombus, the blood is cleaned using a cleaning solution. The gaps between the inner and outer rings of the ball bearing, the gap between the inner sleeve 31 and the rotor assembly 20, and the gap between the sliding bearing and the shaft 21 constitute the cleaning pathway. This cleaning pathway not only lubricates the bearing and prevents blood from flowing into the motor, reducing the risk of hemolysis, but also effectively helps the blood pump dissipate heat, improving the safety, reliability, and stability of the entire vascular blood pump during high-speed operation. Specifically, the perfusion solution injected into the vascular blood pump can be composed of glucose and heparin mixed in a certain proportion, where heparin acts as an anticoagulant.

[0033] Depending on the type of bearing 40 and whether or not a bearing protective sleeve 50 is provided, the squeegee pump of the present invention has at least the following four embodiments: Example

[0034] like Figure 1 As shown, without the bearing protective sleeve 50, both the near-end bearing 40a and the far-end bearing 40b are sliding bearings, directly welded to the inner circumferential surface of the inner sleeve 31. Example

[0035] like Figure 2As shown, the bearing protective sleeve 50 is not provided. The near-end bearing 40a is a ball bearing and the far-end bearing 40b is a sliding bearing, which are directly welded to the inner circumferential surface of the inner sleeve 31. Example

[0036] like Figure 3 As shown, a bearing protective sleeve 50 is provided. Both the near-end bearing 40a and the far-end bearing 40b are sliding bearings. The far-end bearing 40b is welded to the inner circumferential surface of the inner sleeve 31, and the near-end bearing 40a is bonded to the bearing protective sleeve 50. Example

[0037] like Figure 4 As shown, a bearing protective sleeve 50 is provided, wherein the distal bearing 40b is welded to the inner circumferential surface of the inner sleeve 31, and the outer ring of the proximal bearing 40a is bonded to the bearing protective sleeve 50 and to the outer circumferential surface of the rotating shaft 21.

[0038] In Embodiments 2 and 4, although the near-end bearing 40a is not directly welded to the inner wall of the inner sleeve 31, the reliability of the near-end bearing support is improved due to the bearing protective sleeve, which can meet the requirements of the motor.

[0039] like Figure 6 , Figure 7 As shown, the bearing protective cover 50 is made of plastic, preferably engineering plastic PEEK or similar polymer materials. This not only reduces the overall weight but also provides good insulation and corrosion resistance, further reducing the production and processing costs of the blood pump. It can be manufactured by 3D printing using high-hardness polymer materials or by machining using engineering plastics such as PEEK.

[0040] Furthermore, the gap between the inner sleeve 31 and the permanent magnet 22 of the rotor assembly 20 is 0.1mm-0.5mm.

[0041] Preferably, the outer sleeve 32 is made of ferritic alloy material with a thickness of 0.2mm-0.3mm. The outer sleeve 32 has high density and high magnetic flux density, achieving both a small overall thickness and relatively high magnetic permeability. Tests show that when the magnetic sleeve is applied to a duct pump motor, it can achieve 100% magnetic reflux without hysteresis, resulting in smooth motor operation and extremely low eddy current losses. The preferred composition of the ferritic alloy has been detailed in the applicant's previously applied and granted invention patent, "A Magnetic Sleeve and Its Preparation Method and Application" (application number: 202211583059.9), and will not be repeated here.

[0042] The housing 10 is a protective layer formed by epoxy resin potting on the surface of the stator assembly 30 and between the components to isolate the motor's internal and external environments. The advantage of using potting material is that once the components are positioned in the potting mold, they can be reliably supported and fixed, ensuring the precision of the finished product. Furthermore, the potting material has excellent heat dissipation properties, which is also required by intravascular blood pumps.

[0043] like Figures 1-4 As shown, a blood pump includes a drive mechanism. The distal end of a rotating shaft 21 protrudes outside the housing 10 and is fixedly connected to an impeller 60. The impeller 60 is disposed inside a sleeve. The drive device drives the impeller 60 to rotate and draws blood in from the sleeve inlet and pumps it out from the sleeve outlet. Only when the drive mechanism operates stably and without interruption can the impeller 60 continuously pump blood to meet the physiological needs of the human body.

[0044] Depend on Figure 9 , Figure 10 It can be seen that the ends of the outer sleeve 32 and the inner sleeve 31 are rounded to avoid stress concentration that could cause the epoxy resin shell 10 to break.

[0045] It should be noted that the above description describes some embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A drive mechanism, comprising a housing (10) and a rotor assembly (20) and a stator assembly (30) coaxially disposed within the housing (10), wherein the stator assembly (30) comprises an inner sleeve (31) and an outer sleeve (32) coaxially sleeved together, and a hollow cup winding (33) located between the inner sleeve (31) and the outer sleeve (32), characterized in that: The inner sleeve (31) is made of metal, and at least one bearing (40) at each end of the rotor assembly (20) shaft (21) is welded and fixed to the inner wall of the inner sleeve (31); The inner sleeve (31) is provided with a metal sheet (34) extending from the near end. The terminals of the hollow cup winding (33) and the external cable (A) are welded to the metal sheet (34). Three metal sheets (34) are evenly and spaced on the outer wall of the near end of the inner sleeve (31), and the three metal sheets (34) extend from the outer wall of the bearing (40) to the near end.

2. The driving mechanism according to claim 1, characterized in that: The inner sleeve (31) is made of stainless steel with a thickness of 0.1mm-0.2mm, and an insulating and anti-corrosion coating is attached to the inner circumferential wall of the stainless steel sleeve.

3. The driving mechanism according to claim 1, characterized in that: The bearing (40) includes a proximal bearing (40a) and a distal bearing (40b). The proximal bearing (40a) is covered by a bearing protective cover (50). The bearing protective cover (50) includes a first cover (51) and a second cover (52). The openings of the first cover (51) and the second cover (52) are interlocked to form a chamber for accommodating the proximal bearing (40a). The outer wall of the first cover (51) is axially provided with a groove (511) for accommodating a metal sheet (34). The outer wall of the second cover (52) is axially provided with a cable tray (521) for accommodating an external cable (A). The proximal end of the second cover (52) extends a connecting pipe (53) for connecting to a cleaning pipeline (70). The cable tray (521) extends to the wall of the connecting pipe (53).

4. The driving mechanism according to claim 3, characterized in that: The wiring groove (521) and the groove (511) are arranged in a one-to-one correspondence to form a connecting groove. There are 3 sets of connecting grooves. The cross-section of the groove (511) is "U" shaped, and the cross-section of the wiring groove (521) is semi-circular.

5. The driving mechanism according to claim 3, characterized in that: The first cover (51) and the second cover (52) are bonded together with glue. The far end face of the first cover (51) abuts against the near end face of the inner sleeve (31), and the connection is coated with sealant to form a sealed fit.

6. The driving mechanism according to claim 3, characterized in that: The near-end bearing (40a) is a ball bearing, and the far-end bearing (40b) is a sliding bearing. The stepped surface of the inner cavity of the housing abuts against the outer ring of the ball bearing and is fixedly connected by adhesive. The gap between the inner and outer rings of the ball bearing, the gap between the inner sleeve (31) and the rotor assembly (20), and the gap between the sliding bearing and the shaft (21) constitute the cleaning passage.

7. The driving mechanism according to claim 3, characterized in that: The bearing protective cover (50) is made of plastic.

8. The driving mechanism according to claim 1, characterized in that: The gap between the inner sleeve (31) and the permanent magnet (22) of the rotor assembly (20) is 0.1mm-0.5mm.

9. The driving mechanism according to claim 1, characterized in that: The outer sleeve (32) is made of ferritic alloy material with a thickness of 0.2mm-0.3mm.

10. The driving mechanism according to claim 1, characterized in that: The housing (10) is a protective layer formed by epoxy resin potting on the surface of the stator assembly (30) and between the assemblies to isolate the motor from the external environment.

11. A blood pump comprising the drive mechanism according to any one of claims 1-10, characterized in that: The distal end of the rotating shaft (21) protrudes to the outside of the housing (10) and is fixedly connected to the impeller (60). The impeller (60) is located inside the sleeve. The driving device drives the impeller (60) to rotate and draws blood in from the sleeve inlet and pumps it out from the sleeve outlet.

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