Miniature axial flow blood pump for discharging blood and guiding flow

Abstract

The utility model discloses a miniature axial flow blood pump for discharging blood and guiding flow, which comprises a stator assembly, a rotor assembly, a left end bearing, a right end bearing, an impeller and an impeller mounting cylinder, the stator assembly comprises a motor casing, a magnetic conductive stator and a stator winding, and the motor casing comprises an outer casing, a left end cover and a right end cover. The rotor assembly comprises a rotating shaft, a permanent magnet and a rotor sleeve which are sequentially connected from inside to outside; a plurality of notch grooves are formed in the left end of the left end cover, the impeller mounting cylinder comprises a cylinder body and a plurality of insertion strips, each insertion strip is inserted into one notch groove and welded to the left end cover, and the space between any two adjacent insertion strips serves as a blood outlet; a flow guide face is arranged at the position, corresponding to the blood outlet, of the left end of the left end cover and is an arc face. The connection between the insertion strip of the impeller mounting cylinder and the left end cover is convenient, firm and reliable. The arc surface of the left end cover has a flow guide effect, so that the damage to blood cells can be reduced.

Description

Technical Field

[0001] The utility model belongs to the field of interventional medical equipment, and more specifically, relates to a micro axial flow blood pump for blood drainage and diversion. Background Art

[0002] In recent years, interventional axial flow micro blood pumps have become increasingly popular. When a patient's heart is severely damaged and unable to deliver blood, doctors can implant a micro blood pump in the patient's body through minimally invasive surgery to help the patient maintain life. Micro blood pumps have significant advantages in the treatment of high-risk PCI (percutaneous coronary intervention), persistent cardiogenic shock, acute myocardial infarction (AMI) cardiogenic shock, and post-cardiotomy cardiogenic shock (PCCS).

[0003] In the existing interventional micro-axial blood pump, the impeller is installed in the impeller mounting tube, and there is a long strip of blood outlet on the impeller mounting tube (the blood outlet does not extend to the end face of the impeller mounting tube). The impeller discharges the blood flowing into the impeller mounting tube, and the complete annular structure at the end of the impeller mounting tube is connected to the motor housing by circumferential welding. Circumferential welding requires high technical requirements and requires skilled operation to ensure quality. In addition, with such a conventional structure, when the impeller discharges blood, the structure at the end of the motor housing has no guiding effect on the blood, making the blood flow more chaotic, with a greater impact on the blood, and causing more damage to blood cells.

[0004] In addition, the existing interventional micro-axial flow blood pump motor generally supports the rotating shaft by a ball bearing at the high-pressure liquid inlet end of the motor housing + a sliding bearing at the high-pressure liquid outlet end of the motor housing. Since the friction and wear degree of the sliding bearing at the outlet end is greater than that of the ball bearing at the inlet end, the service life is generally not long. In addition, the blood pump motor needs to operate within a wide speed range of 20,000 to 50,000 rpm, which makes the friction state of the sliding bearing different, and the medical risks caused by the wear difference are uncontrollable. Utility Model Content

[0005] In view of the above defects or improvement needs of the prior art, the utility model provides a micro axial flow blood pump for blood drainage and diversion, the connection between the impeller mounting tube and the motor housing is relatively convenient, and the arc surface on the left end cover has a diversion effect, which can reduce damage to blood cells.

[0006] To achieve the above-mentioned purpose, according to the utility model, a micro axial flow blood pump for blood drainage and diversion is provided, characterized in that it includes a stator assembly, a rotor assembly, a left end bearing, a right end bearing, an impeller and an impeller mounting cylinder, wherein:

[0007] The stator assembly includes a motor housing, a magnetic stator and a stator winding which are sequentially connected from the outside to the inside, the motor housing includes an outer shell, a left end cover and a right end cover, and the left end cover and the right end cover are respectively fixedly connected to the left end and the right end of the outer shell;

[0008] The rotor assembly is arranged horizontally and comprises a rotating shaft, a permanent magnet and a rotor sleeve which are sequentially connected from the inside to the outside;

[0009] The left end bearing and the right end bearing are both mounted on the rotating shaft, and the left end bearing and the right end bearing are respectively mounted on the left end cover and the right end cover;

[0010] The left end of the rotating shaft passes through the left end cover and is fixedly connected to the impeller;

[0011] The left end of the left end cover is provided with a plurality of notched grooves, and the notched grooves are evenly arranged circumferentially around the center line of the rotating shaft;

[0012] The impeller mounting cylinder comprises a cylinder body and a plurality of inserts fixed on the cylinder body, all of the inserts are evenly arranged circumferentially around the center line of the rotating shaft, each of the inserts is respectively inserted into one of the notched grooves, and each of the inserts is respectively welded to the left end cover, and the space between any two adjacent inserts serves as a blood outlet, so that the impeller discharges blood from the blood outlet out of the impeller mounting cylinder;

[0013] The left end of the left end cover is provided with a flow guide surface at a position corresponding to the blood outlet, and the flow guide surface is an arc surface, and various notch grooves are provided on the flow guide surface.

[0014] Preferably, it also includes a preload spring mounted on the rotating shaft;

[0015] The left end bearing and the right end bearing are both ball bearings, and the outer ring of the right end bearing is fixedly mounted on the right end cover;

[0016] The left end cover has a horizontal step hole, which is a through hole and includes a first hole, a second hole and a third hole arranged in sequence from left to right and with diameters increasing from small to large. The first step of the inner wall of the left end cover forms the first hole and the second hole, and the second step of the inner wall of the left end cover forms the second hole and the third hole. The left end of the rotating shaft passes through the left end cover at the step hole and is connected to the impeller. There is a first gap between the hole wall of the first hole and the rotating shaft, and the first gap serves as an outlet for high-pressure liquid entering the motor housing. The outer ring of the left end bearing is fixedly mounted on the hole wall of the third hole and abuts against the second step. The outer diameter of the inner ring of the left end bearing is smaller than the hole diameter of the second hole. The inner ring of the left end bearing cooperates with the permanent magnet to clamp the preload spring, and the preload spring applies elastic force to the inner ring of the left end bearing.

[0017] There is a second gap and a third gap between the inner ring of the left end bearing and the inner ring of the right end bearing and the rotating shaft respectively. A force transmission member is also fixedly installed on the rotating shaft, and the force transmission member applies force to the right on the inner ring of the right end bearing under the action of the elastic force of the preloaded spring.

[0018] Preferably, the first step is provided with a chamfer, thereby forming a frustum with a gradually decreasing diameter along the direction from the second hole to the first hole, so that the high-pressure liquid flows from the second hole into the first gap to fill the first gap.

[0019] Preferably, the chamfer angle is 20° to 40°.

[0020] Preferably, the left end and the right end of the rotor sleeve respectively extend beyond the left end and the right end of the permanent magnet, and the left end and the right end of the inner wall of the rotor sleeve are respectively filled with the rotor left potting glue and the rotor right potting glue to seal the permanent magnet in the space between the rotor sleeve and the rotating shaft, and the preload spring rests on the rotor left potting glue.

[0021] Preferably, the first gap is 5 μm to 15 μm.

[0022] Preferably, the second gap is 1 μm to 3 μm, and the third gap is 1 μm to 3 μm.

[0023] Preferably, the distance between the impeller and the left end cover is 0.03 mm to 0.15 mm.

[0024] Preferably, the right end cover includes a bearing mounting cover and a tail cover, the left end of the bearing mounting cover extends into the outer shell and is fixedly connected to the outer shell, the tail cover is fixedly connected to the bearing mounting cover, the right end bearing is fixedly mounted in the bearing cavity of the bearing mounting cover, the bearing mounting cover is provided with a limiting boss, the tail cover is connected with a liquid passing pipe, the inner cavity of the liquid passing pipe is connected with the inner cavity of the tail cover, the left end of the tail cover extends into the bearing mounting cover and presses the outer ring of the right end bearing onto the limiting boss.

[0025] Preferably, the preload spring is in the shape of a spiral, a sleeve or a multi-layer wave, wherein:

[0026] The spiral preload spring is made of biocompatible metal and the end surface close to the left end bearing is ground flat so that the preload force acts evenly on the inner ring of the left end bearing;

[0027] The sleeve-shaped preload spring is made of elastic biocompatible plastic;

[0028] The multi-layer wave-shaped preload spring is made of a strip material wound in a spiral wave-like manner and is made of biocompatible metal.

[0029] In general, the above technical solutions conceived by the utility model can achieve the following beneficial effects compared with the prior art:

[0030] 1) The utility model is a micro axial flow blood pump for blood discharge and diversion. The plug of the impeller mounting tube is inserted into the notch of the motor housing, and then connected by welding, so that the connection is convenient, firm and reliable, and easy to operate. After each plug cooperates with the left end cover, a plurality of blood outlets are formed. Under the rotation of the impeller, the blood is discharged through the blood outlets, and the arc surface of the left end cover has a diversion effect, which can reduce the damage to blood cells.

[0031] 2) In the present invention, a micro-axial blood pump for blood drainage and diversion is provided. The right-end bearing at the inlet of the high-pressure liquid on the motor housing and the left-end bearing at the outlet are both ball bearings to cooperate with the rotating shaft. There is a second gap between the inner ring of the left-end bearing and the rotating shaft, but the two are not independently supported and cannot form a completely suspended and non-contact cooperation form. The second gap is mainly to allow the inner ring of the left-end bearing to move axially under the preload force of the preload spring to compensate for the clearance of the left-end bearing. Due to the very small second gap of the cooperation between the two and the cooperation mode of the two non-independent supports, the inner ring of the left-end bearing will rotate synchronously with the rotating shaft (the two are relatively static) and will not produce friction and wear. The right-end bearing is also a ball bearing and there is a third gap between it and the rotating shaft. Like the left-end bearing, the inner rings of the rotating shaft and the right-end bearing are relatively static and will not produce friction and wear. Therefore, the present invention reduces the uncertainty risk caused by changes in friction state conditions by using ball bearings for both the left-end bearing and the right-end bearing and the inner rings have gaps with the rotating shaft, and can prevent the risk of blood components entering the blood pump motor and coagulating.

[0032] 3) The utility model is a micro axial blood pump for blood drainage and diversion. Since there is a second gap between the inner ring of the left end bearing and the rotating shaft, and the preload spring generates a certain elastic force (axial preload force) acting on the inner ring of the left end bearing, under the action of the preload force, the inner ring of the ball bearing can move axially relatively freely, and the outer ring of the left end bearing is subjected to the axial force of the second step in the opposite direction to the corresponding inner ring, so that the inner and outer rings of the left end bearing can be axially displaced from each other, and the rolling elements inside the left end bearing are clamped by the inner and outer rings and pressed against the raceways of the inner and outer rings, and will not generate noise and vibration wear due to tiny jumps. Therefore, the design of the preload force of the preload spring and the second gap between the inner ring of the left end bearing and the rotating shaft can timely compensate for the tiny clearance caused by the wear of the left end bearing, so that the micro axial blood pump can maintain a stable operating state during the working process. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a cross-sectional view of the utility model;

[0034] Figure 2 yes Figure 1 The enlarged schematic diagram of point A in the middle;

[0035] Figure 3 It is a schematic diagram of the left end cover in the utility model;

[0036] Figure 4 This is a schematic diagram of the force on the left end bearing in the utility model;

[0037] Figure 5a to Figure 5c It is a schematic diagram of various shapes of preload springs in the utility model;

[0038] Figure 6 It is a schematic diagram of the impeller mounting cylinder and the motor housing of the utility model after being separated;

[0039] Figure 7 This is a schematic diagram of the impeller mounting cylinder and the motor housing of the utility model being assembled together DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. In addition, the technical features involved in each embodiment of the utility model described below can be combined with each other as long as they do not conflict with each other.

[0041] Referring to the accompanying drawings, a micro axial blood pump for blood drainage and diversion includes a stator assembly 1, a rotor assembly 2, a left end bearing 3, a right end bearing 4, an impeller 5 and an impeller mounting tube 7. The stator assembly 1 includes a motor housing 11, a magnetic stator and a stator winding connected in sequence from the outside to the inside. The motor housing 11 includes an outer shell 111, a left end cover 112 and a right end cover 113. The left end cover 112 and the right end cover 113 are fixedly connected to the left and right ends of the outer shell 111, respectively. The rotor assembly 2 is arranged horizontally and includes a rotating shaft 21, a permanent magnet 22 and a rotor sleeve 23 connected in sequence from the inside to the outside.

[0042] The left end bearing 3 and the right end bearing 4 are both mounted on the rotating shaft 21 , and the left end bearing 3 and the right end bearing 4 are respectively mounted on the left end cover 112 and the right end cover 113 .

[0043] The left end of the rotating shaft 21 passes through the left end cover 112 and is fixedly connected to the impeller 5 .

[0044] The outer ring of the right end bearing 4 is fixedly mounted on the right end cover 113. The high-pressure liquid is pumped into the liquid pipe by the high-pressure pump, and the liquid pipe allows the high-pressure liquid to enter the motor housing 11 from the right end cover 113 of the motor housing 11, and flow out of the motor housing 11 from the left end cover 112 of the motor housing 11, that is, right-in and left-out. The left end bearing 3 and the right end bearing 4 are both ball bearings, preferably deep groove ball bearings with pure radial force.

[0045] A plurality of notches 1121 are disposed at the left end of the left end cover 112 , and the notches 1121 are evenly arranged circumferentially around the center line of the rotating shaft 21 .

[0046] The impeller mounting tube 7 includes a barrel 72 and a plurality of inserts 73 fixed on the barrel 72, all of the inserts 73 are evenly arranged circumferentially around the center line of the rotating shaft 21, each of the inserts 73 is respectively inserted into one of the notched grooves 1121, and each of the inserts 73 is respectively welded to the left end cover 112, and the space between any two adjacent inserts 73 serves as a blood outlet 71, so that the impeller 5 discharges blood from the impeller mounting tube 7 through the blood outlet 71.

[0047] The left end of the left end cover 112 is provided with a flow guiding surface 1122 at a position corresponding to the blood outlet, and the flow guiding surface 1122 is an arc surface. The flow guiding surface 1122 is provided with various notches 1121 .

[0048] As an indispensable part of the micro axial flow blood pump, the impeller mounting tube 7 is coaxially matched with the impeller 5. The impeller mounting tube 7 is a hollow structure, with a metal spiral conduit sleeved on one end away from the impeller 5, and a number of inserts 73 are evenly arranged along the circumference of the end close to the impeller 5. The inserts 73 are inserted into the notch grooves 1121 corresponding to the left end cover 112. The left end cover 112 and the impeller mounting tube 7 are made of the same metal material, and the connection is firmly welded with precision laser welding equipment. The several inserts 73 on the impeller mounting tube 7 cooperate with the left end cover 112 to form a blood outlet 71, and under the rotation of the impeller 5, the blood is discharged through the blood outlet 71. The smooth arc surface of the left end cover 112 can reduce damage to blood cells and has a diversion effect.

[0049] The present invention further comprises a preload spring 6 which is mounted on the rotating shaft 21 .

[0050] The left end cover 112 has a horizontal step hole 114, which is a through hole and includes a first hole 1141, a second hole 1142 and a third hole 1143 which are arranged from left to right and have diameters from small to large, that is, the aperture of the first hole 1141 is smaller than the aperture of the second hole 1142 and smaller than the aperture of the third hole 1143. The first hole 1141 and the third hole 1143 are directly connected to the external environment of the left end cover 112. The first step 115 on the inner wall of the left end cover 112 forms the first hole 1141 and the second hole 1142. The second step 116 of the inner wall of the cover 112 forms the second hole 1142 and the third hole 1143. The left end of the rotating shaft 21 passes through the left end cover 112 from the step hole 114 and is connected to the impeller 5. There is a first gap 1144 between the hole wall of the first hole 1141 and the rotating shaft 21, that is, the gap between the two is matched. The first gap 1144 serves as an outlet (overflow port) for the high-pressure liquid in the motor housing 11. The high-pressure liquid in the motor housing 11 is pumped into the high-pressure pump inside and outside to prevent the blood outside the motor housing 11 from flowing back into the blood pump. The outer ring of the left end bearing 3 is fixedly mounted on the hole wall of the third hole 1143 and abuts against the second step 116. The outer diameter of the inner ring of the left end bearing 3 is smaller than the hole diameter of the second hole 1142, so that the high-pressure liquid in the motor housing 11 flows out of the left end bearing 3 and enters the second hole 1142 to prevent the inner ring of the left end bearing 3 from scratching the second step 116 during rotation. The high-pressure liquid then flows out of the left end cover 112 through the first gap 1144 connected to the second hole 1142. There is a second gap between the inner ring of the left end bearing 3 and the rotating shaft 21. The inner ring of the left end bearing 3 cooperates with the permanent magnet 22 to clamp the preload spring 6, and the preload spring 6 applies elastic force (preload force) on the inner ring of the left end bearing 3. The second gap 1145 allows the inner ring of the left end bearing 3 to reciprocate along the axial direction of the rotating shaft 21 under the elastic force of the preload spring 6 and allows the inner ring of the left end bearing 3 to still rotate synchronously with the rotating shaft 21. A force transmission member 26 is also fixedly mounted on the rotating shaft 21. The force transmission member 26 applies force to the right on the inner ring of the right end bearing 4 under the elastic force of the preload spring 6. The force transmission member 26 can be a spring member (the spring member is clamped by the permanent magnet 22 and the inner ring of the right end bearing 4), or a sleeve made of biocompatible plastic.

[0051] There is a third gap between the inner ring of the right end bearing 4 and the rotating shaft 21, and the third gap allows the inner ring of the right end bearing 4 and the rotating shaft 21 to still rotate synchronously. Therefore, the second gap and the third gap are very small, and the line contact between the inner ring of the left end bearing 3 and the inner ring of the right end bearing 4 and the rotating shaft 21 is greater than the point contact friction between the balls and the raceway, so the balls have priority to produce relative motion. The matching gap between the rotating shaft 21 and the inner ring is very small. From a microscopic level, there is still molecular adsorption (and the viscosity of water molecules in high-pressure liquid), which will also prevent the inner ring and the rotating shaft 21 from relative rotation, so the inner ring and the rotating shaft 21 rotate synchronously, and there is almost no circumferential wear on the rotating shaft 21 and the inner ring of the bearing.

[0052] Like the left bearing 3, there is a gap between the right bearing 4 and the rotating shaft 21. The left bearing 3 and the right bearing 4 do not need to adopt a transition or interference fit, which will cause assembly troubles, and the rotating shaft 21 is prone to bending under force, and the fit is prone to produce debris that is difficult to clean.

[0053] In fact, when ball bearings are used, friction only exists between the rolling element and the raceway. Taking ball bearings as an example, the ball and the raceway are in point contact and rolling friction, so the wear is very small. Because the size of the micro blood pump axial flow motor of the present invention is very small, it is basically unlikely to use roller bearings or needle bearings in actual situations, because the contact between rollers and needles is line contact, and compared with the point contact of the ball of the ball bearing, the contact area between the roller, needle and the raceway is large, and the friction will be a little greater, which is easy to cause relative rotation between the inner ring of the ball bearing and the rotating shaft 21, thereby aggravating the wear.

[0054] In addition, since there are gaps between the rotating shaft 21 and the inner rings of the left end bearing 3 and the right end bearing 4, the rotating shaft 21 may produce axial movement. If there is axial movement, it means that there is an external force, and the preload force of the preload spring 6 needs to resist this external force. As long as the preload force is slightly larger than the external force, the rotor assembly 2 is stable as a whole. This external force is mainly the force of blood (fluid) on the impeller 5 (because the motor housing 11 is full of high-pressure liquid, the flow rate of high-pressure liquid is actually very small, and the disturbance of high-pressure liquid is basically negligible). After the impeller 5 rotates, it will form a force that pulls the rotor assembly 2 to the left, but this force fluctuates within a certain range under the disturbance of blood. The preload force of the preload spring 6 can offset the fluctuation of the force of blood (fluid) on the impeller 5, and prevent the rotating shaft 21 from moving along its own axial direction. In addition, the axial sliding of the rotating shaft 21 relative to the inner rings of the left-end bearing 3 and the right-end bearing 4 takes up very little time in the entire life cycle. Only when the ball bearing produces a small clearance due to its own wear will the inner ring have a small axial movement, so there is almost no axial wear.

[0055] The inner cavity of the impeller mounting cylinder 7 is communicated with the first gap 1144 , and the high-pressure liquid that flows out from the first gap 1144 and mixes with the blood in the impeller mounting cylinder 7 can flow out from the blood outlet 71 .

[0056] The left end and the right end of the rotor cover 23 respectively extend beyond the left end and the right end of the permanent magnet 22, and the left end and the right end of the inner wall of the rotor cover 23 are respectively filled with a rotor left potting glue 24 and a rotor right potting glue 25 to seal the permanent magnet 22 in the space between the rotor cover 23 and the rotating shaft 21, and the preload spring 6 rests on the rotor left potting glue 24.

[0057] The right end cover 113 includes a bearing mounting cover 1131 and a tail cover 1132. The left end of the bearing mounting cover 1131 extends into the outer shell 111 and is fixedly connected to the outer shell 111. The tail cover 1132 is fixedly connected to the bearing mounting cover 1131. The right end bearing 4 is fixedly mounted in the bearing cavity of the bearing mounting cover 1131. A limiting boss is provided on the bearing mounting cover 1131. A liquid passing pipe 8 is connected to the tail cover 1132. The inner cavity of the liquid passing pipe 8 is connected to the inner cavity of the tail cover 1132. The left end of the tail cover 1132 extends into the bearing mounting cover 1131 and presses the outer ring of the right end bearing 4 onto the limiting boss.

[0058] The assembly sequence of the utility model is as follows: 1) the rotor assembly 2 is installed into the stator assembly 1; 2) the left end bearing 3 and the left end cover 112 are respectively installed into the stator assembly 1, and the rotating shaft 21 passes through the inner hole of the left end bearing 3; 3) the impeller 5 is installed at the left end of the rotating shaft 21, and then the impeller mounting tube 7 is coaxially installed into the mounting hole on the left end cover 112; 4) the bearing mounting cover 1131, the tail cover 1132 and the liquid pipe 8 are installed.

[0059] The rotating shaft 21 (or rotor assembly 2) of the utility model is supported by two ball bearings on the left and right sides. The rolling friction of the ball bearings is significantly lower than the wear of the existing sliding bearings, which reduces the generation of wear particles. The rotor assembly 2 and the impeller 5 thereon can maintain a stable operating state for a long time. The high-pressure liquid inside the motor circulates in the motor housing 11, passes through the inside of the right end bearing 4, the gap between the stator assembly 1 and the rotor assembly 2, and the inside of the left end bearing 3 in sequence, and then enters the first gap 1144 between the left end bearing 3 and the left end cover 112, and then flows out of the micro motor from the first gap 1144 (radial gap, size 5μm ~ 15μm), enters the space formed by the impeller 5 and the left end cover 112 (the axial spacing between the impeller 5 and the left end cover 112 is 0.03mm ~ 0.15mm) and continuously flows out from the blood outlet 71 into the human blood. The chamfer 1151 of the edge of the first step 115 is α and α=20-40°, so that a truncated table with a gradually decreasing diameter is formed along the direction from the second hole 1142 to the first hole 1141, so that the high-pressure liquid flows from the second hole 1142 into the first gap 1144 to fill the first gap 1144, which is conducive to the high-pressure liquid filling the first gap 1144 and reducing the risk of blood backflow. Due to the continuous injection of high-pressure liquid, the liquid pressure inside the motor housing 11, the first gap 1144, and the space between the impeller 5 and the left end cover 112 can be greater than the adjacent blood pressure, and blood components will not enter these areas to cause coagulation blockage. The material of the left end cover 112 is a biocompatible metal (stainless steel or titanium alloy).

[0060] Since the preload spring 6 is mounted on the rotating shaft 21, one end of the preload spring 6 abuts against the inner ring of the left end bearing 3, and the other end presses on the left potting glue 24 of the rotor. After the preload spring 6 is installed, it is in a compressed state, that is, the preload spring 6 can generate a certain elastic force (axial preload force, F1 is 0.1N~1N) acting on the inner ring of the left end bearing 3, and the outer ring of the left end bearing 3 is subjected to the axial force F2 opposite to the corresponding inner ring, so that the inner and outer rings of the left end bearing 3 are mutually dislocated along the axial direction, and the ball is therefore tightly attached to the inner and outer ring raceways, and no noise and vibration wear will be generated due to slight jumping. Obviously, although the wear amount inside the ball bearing itself is small, for long-life service conditions, it is necessary to consider the increase in bearing clearance caused by the accumulation of wear. In order to keep the micro blood pump in a stable operating state during operation, the inner ring of the left end bearing 3 needs to move relatively freely along the axial direction under the action of the preload force to timely compensate for the small clearance caused by the wear of the left end bearing 3 itself. Therefore, the inner ring of the left end bearing 3 and the rotating shaft 21 are clearance-matched, and there is a second gap 1145 (radial gap, size is 1μm~3μm) between the two. The inner ring of the right end bearing 4 and the rotating shaft 21 have a third gap (radial gap, size is 1μm~3μm), and the force and movement of the inner ring of the right end bearing 4 refer to the left end bearing 3.

[0061] See also Figure 5a to Figure 5c The preload spring 6 usually adopts a spiral, sleeve-shaped and multi-layer wave-shaped structure. The preload spring 6 with a spiral structure is usually made of biocompatible metals, such as stainless steel, nickel-titanium memory alloy, and titanium alloy. Its end face adopts a local grinding process, which can make the preload force act more evenly on the inner ring of the left end bearing 3. The sleeve-shaped preload spring 6 has a relatively simple structure and adopts biocompatible plastics with good elasticity, such as silicone, PA, TPU, etc. The preload spring 6 with a multi-layer wave-shaped structure is formed by spirally winding a strip material, and the optional material is a biocompatible metal, such as stainless steel, nickel-titanium memory alloy, and titanium alloy.

[0062] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A micro axial flow blood pump for blood drainage and diversion, characterized in that: It includes a stator assembly, a rotor assembly, a left end bearing, a right end bearing, an impeller and an impeller mounting cylinder, wherein: The stator assembly includes a motor housing, a magnetic stator and a stator winding which are sequentially connected from the outside to the inside, the motor housing includes an outer shell, a left end cover and a right end cover, and the left end cover and the right end cover are respectively fixedly connected to the left end and the right end of the outer shell; The rotor assembly is arranged horizontally and comprises a rotating shaft, a permanent magnet and a rotor sleeve which are sequentially connected from the inside to the outside; The left end bearing and the right end bearing are both mounted on the rotating shaft, and the left end bearing and the right end bearing are respectively mounted on the left end cover and the right end cover; The left end of the rotating shaft passes through the left end cover and is fixedly connected to the impeller; The left end of the left end cover is provided with a plurality of notched grooves, and the notched grooves are evenly arranged circumferentially around the center line of the rotating shaft; The impeller mounting cylinder comprises a cylinder body and a plurality of inserts fixed on the cylinder body, all of the inserts are evenly arranged circumferentially around the center line of the rotating shaft, each of the inserts is respectively inserted into one of the notched grooves, and each of the inserts is respectively welded to the left end cover, and the space between any two adjacent inserts serves as a blood outlet, so that the impeller discharges blood from the blood outlet out of the impeller mounting cylinder; The left end of the left end cover is provided with a flow guide surface at a position corresponding to the blood outlet, and the flow guide surface is an arc surface, and various notch grooves are provided on the flow guide surface.

2. A micro axial flow blood pump for blood drainage and diversion according to claim 1, characterized in that: It also includes a preload spring mounted on the rotating shaft; The left end bearing and the right end bearing are both ball bearings, and the outer ring of the right end bearing is fixedly mounted on the right end cover; The left end cover has a horizontal step hole, which is a through hole and includes a first hole, a second hole and a third hole arranged in sequence from left to right and with diameters increasing from small to large. The first step of the inner wall of the left end cover forms the first hole and the second hole, and the second step of the inner wall of the left end cover forms the second hole and the third hole. The left end of the rotating shaft passes through the left end cover at the step hole and is connected to the impeller. There is a first gap between the hole wall of the first hole and the rotating shaft, and the first gap serves as an outlet for high-pressure liquid entering the motor housing. The outer ring of the left end bearing is fixedly mounted on the hole wall of the third hole and abuts against the second step. The outer diameter of the inner ring of the left end bearing is smaller than the hole diameter of the second hole. The inner ring of the left end bearing cooperates with the permanent magnet to clamp the preload spring, and the preload spring applies elastic force to the inner ring of the left end bearing. There is a second gap and a third gap between the inner ring of the left end bearing and the inner ring of the right end bearing and the rotating shaft respectively. A force transmission member is also fixedly installed on the rotating shaft, and the force transmission member applies force to the right on the inner ring of the right end bearing under the action of the elastic force of the preloaded spring.

3. A micro axial flow blood pump for blood drainage and diversion according to claim 2, characterized in that: The first step is provided with a chamfer, so as to form a frustum with a gradually decreasing diameter along the direction from the second hole to the first hole, so that the high-pressure liquid flows from the second hole into the first gap to fill the first gap.

4. A micro axial flow blood pump for blood drainage and diversion according to claim 3, characterized in that: The chamfer angle is 20° to 40°.

5. The micro axial flow blood pump for blood drainage and diversion according to claim 2, characterized in that: The left end and the right end of the rotor sleeve respectively extend beyond the left end and the right end of the permanent magnet, and the left end and the right end of the inner wall of the rotor sleeve are respectively filled with the rotor left potting glue and the rotor right potting glue to seal the permanent magnet in the space between the rotor sleeve and the rotating shaft, and the preload spring rests on the rotor left potting glue.

6. The micro axial flow blood pump for blood drainage and diversion according to claim 2, characterized in that: The first gap is 5 μm to 15 μm.

7. A micro axial flow blood pump for blood drainage and diversion according to claim 2, characterized in that: The second gap is 1 μm to 3 μm, and the third gap is 1 μm to 3 μm.

8. The micro axial flow blood pump for blood drainage and diversion according to claim 2, characterized in that: The distance between the impeller and the left end cover is 0.03 mm to 0.15 mm.

9. The micro axial flow blood pump for blood drainage and diversion according to claim 1, characterized in that: The right end cover includes a bearing mounting cover and a tail cover, the left end of the bearing mounting cover extends into the outer shell and is fixedly connected to the outer shell, the tail cover is fixedly connected to the bearing mounting cover, the right end bearing is fixedly mounted in the bearing cavity of the bearing mounting cover, the bearing mounting cover is provided with a limiting boss, the tail cover is connected with a liquid passing pipe, the inner cavity of the liquid passing pipe is connected to the inner cavity of the tail cover, the left end of the tail cover extends into the bearing mounting cover and presses the outer ring of the right end bearing on the limiting boss.

10. The micro axial flow blood pump for blood drainage and diversion according to claim 2, characterized in that: The preload spring is in the shape of a spiral, a sleeve or a multi-layer wave, wherein: The spiral preload spring is made of biocompatible metal and the end surface close to the left end bearing is ground flat so that the preload force acts evenly on the inner ring of the left end bearing; The sleeve-shaped preload spring is made of elastic biocompatible plastic; The multi-layer wave-shaped preload spring is made of a strip material wound in a spiral wave-like manner and is made of biocompatible metal.

Images