A centrifugal blood pump with constant rotational speed and pulsatile flow output

Abstract

The application discloses a centrifugal blood pump with constant rotating speed and output pulsating flow, which is characterized by the following technical scheme: a steering gear assembly is arranged in the pump body, an impeller is arranged in the inner cavity of the pump shell, a bevel gear I is arranged at the root of the blade uniformly arranged on the circumference of the impeller, and a driving motor II is used for driving the impeller to rotate; a driving motor I is used for driving the steering gear assembly to work, the steering gear assembly comprises a box body, two output inner gear rings with opposite rotating directions which can rotate axially in the box body, and an input inner gear ring; a steering gear is arranged in the middle of the box body, the steering gear is sleeved on the rotating main shaft of the impeller, one end of the steering gear is engaged with the bevel gear I through the bevel gear II in the impeller, and the straight gear at the other end is connected with an alternate steering mechanism so that the deflection angle of the blade is changed alternately, the rotating range of the blade angle is adjusted by the independent motor driving the related gear mechanism, the blade can be effectively and reliably driven to perform high-frequency angle adjustment, and the blood flow output by the blood pump can meet the pulsating demand of human body under the condition that the rotating speed is constant.

Description

Technical Field

[0001] This invention belongs to the field of centrifugal pump technology, specifically a centrifugal blood pump that outputs pulsating flow rate at constant speed. Background Technology

[0002] Heart failure is one of the leading causes of cardiovascular disease in its late stages, seriously endangering patients' lives. When drug therapy is ineffective and donors are scarce, implanting a blood pump becomes an effective treatment option. Currently, blood pumps have undergone three generations of development, with axial flow pumps and centrifugal pumps being the main clinically used types. These are typically installed between the left ventricle and the aorta, using the rotation of an impeller to assist the heart in pumping blood from the left ventricle to the aorta. However, existing blood pumps generally use a constant speed for assistance, resulting in a blood flow rate lacking the pulsating energy of a natural heart. Clinical studies have shown that long-term use of constant-flow blood pumps can lead to a lack of necessary blood flow pulsation, potentially causing aortic valve insufficiency, gastrointestinal bleeding, thrombosis, and even multiple organ failure. This severely limits the long-term use of blood pumps in the human body, impacting patients' quality of life and safety.

[0003] To address these issues, experts have explored solutions, one of which involves altering the blood flow output by changing the pump's rotational speed. However, to achieve a pulsating blood flow output that matches the body's frequency and energy by adjusting the pump's rotational speed, the pump needs to reach a variable frequency of 1-2 Hz, with a rotational speed range of 2000-5000 RPM / min. This places extremely high demands on the performance of the pump's drive system. Furthermore, due to the numerous limitations imposed on pump size by the human body environment, conventional pumps struggle to meet these requirements.

[0004] Existing patents disclose a centrifugal blood pump that can achieve stable operation at low speeds, but its structural design does not consider pulsating conditions and cannot meet the pulsating requirements of human blood. Another disclosed centrifugal pump impeller can adjust the total length and angle of the arc-shaped fixed blades and arc-shaped plug-in adjustable blades on the impeller to meet different head and flow rate requirements. However, its blade structure is complex, and the adjustment precision is not stable enough. Furthermore, there are fixed gaps in the blade extension and retraction adjustment structure, which can cause blood stagnation and thrombosis when used in the in vivo blood environment, endangering the patient's life. Another patent achieves flow rate regulation by changing the motor speed. It uses a program to periodically change the speed to alter the flow rate. Although it considers pulsating characteristics in the motor design, it essentially outputs pulsating flow through speed regulation. A typical motor drive system cannot enable a blood pump to achieve a pulsating blood flow similar to that of a natural heart.

[0005] One paper proposes a device for in-service adjustment of pump blade angle based on a low-tooth-difference mechanism. This device adjusts the centrifugal pump blade angle through a power source that drives the impeller. However, its adjustment mechanism is very large and has many dead zones in blood flow, making it difficult to apply to blood pumps in the human body. Another paper proposes a blade adjustment device for a hydraulic pump with an independent drive motor. It uses a worm gear structure and adjusts the blade angle by manually operating a lever to move the blades up and down. This adjustment mechanism requires manual operation and has a large axial length, making it difficult to apply to micro-fluidic machinery like blood pumps that need to be implanted in the body.

[0006] In summary, existing technologies struggle to solve the problem of centrifugal blood pumps outputting pulsating flow rates, necessitating the development of a blood pump that can reliably output a flow rate similar to that of a natural heartbeat. Summary of the Invention

[0007] To address the aforementioned problems, this invention proposes a centrifugal blood pump with a constant-speed, pulsating flow rate. This design places low demands on the blood pump drive system and allows for rapid adjustment of the pulsating flow rate. Specifically, this invention is a centrifugal blood pump with an adjustable (0-90°) angle between the blades and the impeller surface. The output flow rate is positively correlated with the blade angle. This design achieves this without excessively increasing the pump's volume (original volume 46×46×28mm). 3 A gear mechanical structure was designed, along with a drive source for changing the blade installation angle. The blade angle rotation range is adjusted by driving the relevant gear mechanism with an independent motor. This blade angle adjustment structure with an independent drive source can effectively and reliably drive the blade to perform high-frequency angle adjustment, so that it can output blood flow that meets the human body's pulsation requirements under the condition of constant speed.

[0008] This invention is achieved through the following technical solution:

[0009] A centrifugal blood pump that outputs pulsating flow rate at constant speed is characterized in that it includes a pump casing, an impeller, a pump body, an impeller, blades, and a steering gear assembly, wherein the pump body is located below the pump casing, and the impeller is rotatably mounted between the bottom of the pump casing and the pump body.

[0010] The pump body is equipped with a steering gear assembly, a drive motor II and a drive motor I. An impeller is located at the center of the pump casing cavity, and several blades are evenly arranged around the circumference of the impeller. A bevel gear I is located at the root of each blade. The drive motor II is used to drive the impeller to rotate, thereby driving the blades to rotate.

[0011] The drive motor I is used to drive the steering gear assembly to work. The steering gear assembly includes a housing and two output internal gear rings and an input internal gear ring that are axially rotatable in opposite directions within the housing.

[0012] A steering gear is provided in the middle of the housing. The steering gear is sleeved on the rotating main shaft of the impeller. One end of the steering gear meshes with bevel gear I through bevel gear II inside the impeller. The blades are deflected by rotating the two meshing bevel gears. The spur gear at the other end of the steering gear is connected to an alternating steering mechanism so that the deflection angle of the blades changes alternately in the clockwise and counterclockwise directions.

[0013] Furthermore, the inner ring of the input internal gear ring meshes with the rotating gear connected to the motor shaft of the drive motor I. An intermediate gear I and an intermediate gear II are provided between the output internal gear ring and the input internal gear ring. The intermediate gear II meshes with the intermediate gear I and the input internal gear ring respectively. The intermediate gear I meshes with the output internal gear ring. The drive motor I drives the input internal gear ring to rotate, and then the rotation is transferred to the output internal gear ring through the intermediate gear II and the intermediate gear I, so that the input internal gear ring and the output internal gear ring rotate in opposite directions.

[0014] Furthermore, the alternating steering mechanism includes a double gear I and a double gear II, each of which includes a full gear and a half gear. The two half gears rotate in opposite directions, and both the double gear I and the double gear II mesh with the intermediate steering gear.

[0015] The steering gear is isolated from the impeller rotating shaft by a sleeve, and the spur gear at one end of the steering gear meshes with the half gears of double gear I and double gear II respectively. The full gear of double gear I meshes with the output internal gear ring, and the full gear of double gear II meshes with the input internal gear ring.

[0016] Furthermore, a baffle I is provided above the output internal gear ring, a baffle II is provided at the bottom of the input internal gear ring, and two bosses are provided on the housing for fixing baffle I and baffle II.

[0017] The double gear II is positioned by the hole on the baffle II and is axially fixed by the boss on the first shaft; the double gear I is positioned by the hole on the baffle I and is axially fixed by the boss on the second shaft.

[0018] The intermediate gear I is positioned and connected to the holes on the baffle II and baffle I respectively via the third shaft, and the intermediate gear II is positioned and connected to the holes on the baffle II and baffle I via the fourth shaft.

[0019] Furthermore, a bearing is also installed on the rotating main shaft of the impeller. The outer edge of the bearing is close to the hollow wall in the middle of the bottom of the housing, and one end of the bearing is installed close to the drive motor II, while the other end is positioned and fixed by the baffle II.

[0020] Furthermore, the bottom of the pump casing is positioned and installed with the raised steps of the impeller via a positioning groove.

[0021] Furthermore, the bottom of the blade is sunk into the fixing groove of the impeller. The blade includes a blade body, and a stalk is provided at the root of the blade body. A bevel gear I provided at the front end of the stalk meshes with the bevel gear inside the impeller through a hole on the circumference of the impeller. A flexible material is provided below the blade body. One end of the flexible material is wrapped around the blade, and the other end is installed in the gap in the groove of the impeller.

[0022] Furthermore, the drive motor I is mounted on the bottom plate of the housing and is fixed by a ring of steel protruding from the bottom plate.

[0023] Furthermore, the drive motor II is fixed at the bottom of the pump body, and the output shaft of the drive motor II cooperates with the rotating main shaft of the impeller through a crescent groove to drive the main shaft to rotate.

[0024] Furthermore, the drive motor II includes several circumferentially symmetrical threaded holes and several symmetrical countersunk holes. The bottom of the pump body is provided with threaded holes. The drive motor II is fixed to the bottom of the pump body by screw I. The bottom of the housing is provided with holes. The housing is mounted on the drive motor II by screw II.

[0025] The beneficial effects of this invention are as follows:

[0026] (1) This invention uses a steering gear assembly to drive the blades to make regular clockwise and counterclockwise deflection angle changes on the bladed disk, and designs an independent blade adjustment drive source. By utilizing the flow regulation of blade angle changes, it realizes the fluctuating delivery of blood flow. Compared with the pulsating flow output of ordinary speed regulation, its adjustment is simple, reliable and has a high frequency;

[0027] (2) The centrifugal blood pump that can output pulsating flow rate described in this invention can change the blood pulsation pattern by designing the gear ratio of the steering gear assembly according to the actual auxiliary effect requirements during the development of the blood pump, so that the blood flow has a pulsation similar to normal physiology and improves the auxiliary effect.

[0028] (3) The steering gear assembly described in this invention has a simple structure. The steering gear assembly is installed under the pump housing. The structure is compact and does not excessively increase the volume of the blood pump. This can avoid excessive blood loss and reduce the probability of complications such as hemolysis and thrombosis.

[0029] In summary, this design allows the steering gear assembly to adjust the blade mounting angle, thereby regulating the pump's output flow rate. By controlling the rotation of drive motor I, the transmission of each gear and the two internal gear rings can be affected, thus adjusting the rotation direction and angle of the blades. This produces a physiologically characteristic pulsating pumping effect on the blood flowing into the pump housing, meeting different flow requirements and blood pumping demands under pulsating conditions. It provides a more flexible and adjustable centrifugal blood pump to meet the pulsating flow requirements of heart failure patients and reduce the risk of complications. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the centrifugal blood pump structure of the present invention, which can output pulsating flow rate;

[0031] Figure 2 a and 2b are respectively the blade structure diagram of the present invention and Figure 1 Enlarged view of a specific area;

[0032] Figure 3 This is a top view of the pump body and its internal structure according to the present invention;

[0033] Figure 4 for Figure 3 A cross-sectional view of the structure along direction A;

[0034] Figure 5 for Figure 3 A cross-sectional view of the structure along direction B;

[0035] Figure 6 This is a partial exploded view of the pump body steering gear assembly of the present invention;

[0036] Figure 7 This is a schematic diagram showing the installation positions of the two drive motors of the present invention;

[0037] Figure 8 This is a schematic diagram of the drive motor I;

[0038] Figure 9 This is a schematic diagram of the drive motor II.

[0039] Reference numerals: 1. Pump casing; 2. Impeller; 3. Pump body; 4. Impeller; 5. Blade; 50. Blade holder; 51. Blade body; 52. Flexible material; 6. Steering gear assembly; 7. Housing; 8. Steering gear; 9. First shaft; 10. Baffle I; 11. Output internal gear ring; 12. Double gear I; 13. Second shaft; 14. Screw I; 15. Drive motor II; 150. Countersunk hole; 151. Crescent groove; 152. Threaded hole; 16. Bearing; 17. Double gear II; 18. Baffle II; 19. Input internal gear ring; 20. Sleeve; 21. Intermediate gear I; 22. Intermediate gear II; 23. Third shaft; 24. Fourth shaft; 25. Drive motor I; 26. Screw II; 27. Bevel gear I; 28. Bevel gear II. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0041] As shown in the figure, a centrifugal blood pump that outputs pulsating flow at constant speed is characterized by comprising a pump housing 1, an impeller 2, a pump body 3, an impeller 4, blades 5, and a steering gear assembly 6. The pump body 3 is located below the pump housing 1, and the impeller 2 is rotatably mounted between the bottom of the pump housing 1 and the pump body 3. The bottom of the pump housing 1 is positioned and mounted with the protruding step of the impeller 2 through a positioning groove.

[0042] The pump body 3 is internally equipped with a steering gear assembly 6, a drive motor II 15, and a drive motor I 25. An impeller 4 is located at the center of the pump housing 1's inner cavity, with four blades 5 evenly distributed around the circumference of the impeller 4. A bevel gear I 27 is located at the root of each blade 5. The drive motor II 15 is fixed to the bottom of the pump body 3 by screws I 14. The output shaft of the drive motor II 15 engages with the rotating shaft of the impeller 4 through a semi-circular groove 151, thereby driving the rotating shaft of the impeller 4 to rotate, which in turn drives the blades 5 to rotate. To improve the rotational flexibility between the rotating shaft of the impeller 4 and the housing 7, a bearing 16 is also installed on the rotating shaft of the impeller 4. The outer edge of the bearing 16 is tightly attached to the hollow wall at the bottom center of the housing 7, with one end of the bearing 16 installed close to the drive motor II 15 and the other end positioned and fixed by a baffle II 18. The housing 7 is mounted on the drive motor II 15 and is fixed to the drive motor II 15 by screws II 26 and threaded holes.

[0043] The drive motor I25 is mounted on the bottom plate of the housing 7 and is fixed by a ring of steel protruding from the bottom plate. The drive motor I25 is used to drive the steering gear assembly 6 to work. The steering gear assembly 6 includes the housing 7 and two output internal gear rings 11 and input internal gear rings 19 that can rotate axially in opposite directions within the housing 7.

[0044] The input internal gear ring 19 is located below the output internal gear ring 11. The inner ring of the input internal gear ring 19 meshes with the rotating gear connected to the motor shaft of the drive motor I25. An intermediate gear I21 and an intermediate gear II22 are provided between the output internal gear ring 11 and the input internal gear ring 19. The intermediate gear II22 meshes with the intermediate gear I21 and the input internal gear ring 19 respectively. The intermediate gear I21 meshes with the output internal gear ring 11. The drive motor I25 drives the input internal gear ring 19 to rotate, and then the rotation is transferred to the output internal gear ring 11 through the intermediate gear II22 and the intermediate gear I21. That is, under the action of the change of rotation direction of the two intermediate gears, the input internal gear ring 19 and the output internal gear ring 11 rotate in opposite directions.

[0045] A steering gear 8 is provided in the middle of the housing 7. The steering gear 8 is sleeved on the rotating main shaft of the impeller 4 and is installed concentrically with the rotating shaft of the impeller 4. The steering gear 8 is isolated from the rotating main shaft of the impeller 4 by the sleeve 20, so that they do not affect each other's rotation. One end of the steering gear 8 meshes with the bevel gear I 27 through the bevel gear II 28 inside the impeller. The two meshing bevel gears rotate to deflect the blade 5. The spur gear at the other end of the steering gear 8 is connected to an alternating steering mechanism so that the deflection angle of the blade 5 changes alternately in the clockwise and counterclockwise directions.

[0046] The alternating steering mechanism includes a double gear I12 and a double gear II17, each of which includes a full gear and a half gear. Both the double gear I12 and the double gear II17 mesh with the intermediate steering gear 8.

[0047] Furthermore, the spur gear at one end of the steering gear 8 meshes with the half gears of the double gear I 12 and the double gear II 17 respectively. The full gear of the double gear I 12 meshes with the output internal gear ring 11, and the full gear of the double gear II 17 meshes with the input internal gear ring 19. The rotation direction of the two double gears is determined by the internal gear rings they mesh with. Therefore, the two half gears rotate in opposite directions, so there are two meshing methods to transmit rotation to the steering gear 8 in one rotation cycle. The two half gears with opposite rotation directions drive the output steering gear 8 to rotate alternately in clockwise and counterclockwise directions. One end of the steering gear 8 meshes with the bevel gear I 27 through the bevel gear II 28 inside the impeller. The two rotating bevel gears further drive the angle of the blade 5 to change. In one rotation cycle, the blade angle can change in both clockwise and counterclockwise directions, so that the blade angle changes regularly, thereby affecting the output flow of the centrifugal blood pump.

[0048] The blade 5 is recessed at its bottom within the fixed groove of the impeller 2. The blade 5 includes a blade body 51, with a stalk 50 at the root of the blade body 51. A bevel gear I 27 at the front end of the stalk meshes with a bevel gear II inside the impeller 4 through holes on all four sides. A flexible material 52 is disposed below the blade body 51, with one end wrapped around the blade 5 and the other end installed in a slot within the groove of the impeller 2. The flexible material 52 deforms when the blade 5 rotates, allowing the blade 5 to rotate at a certain angle within the fixed groove of the impeller 2, ensuring normal blade operation.

[0049] Furthermore, a baffle I 10 is provided above the output internal gear ring 11, a baffle II 18 is provided at the bottom of the input internal gear ring 19, and two bosses are provided on the housing 7; thus, the baffle I 10 and the baffle II 18 are easy to install.

[0050] The double gear II17 is positioned by the hole on the baffle II18 and is axially fixed by the boss on the first shaft 9; the double gear I12 is positioned by the hole on the baffle I10 and is axially fixed by the boss on the second shaft 13.

[0051] The intermediate gear I21 is positioned and connected to the holes on the baffle II18 and baffle I10 respectively through the third shaft 23, that is, axial positioning is achieved through the boss on the third shaft 23;

[0052] The intermediate gear II22 is positioned and connected to the holes on the baffle 18II and the baffle I10 via the fourth shaft 24, and is axially positioned via the boss on the fourth shaft 24.

[0053] Furthermore, the drive motor II 15 includes a plurality of circumferentially symmetrical threaded holes 152 and a plurality of symmetrical countersunk holes 150. The bottom of the pump body 3 is provided with threaded holes. The drive motor II 15 is fixed to the bottom of the pump body 3 by screw I 14. The bottom of the housing 7 is provided with holes. The housing 7 is mounted on the drive motor II 15 by screw II 26.

[0054] Work process:

[0055] During operation, driven by drive motor II15, the impeller 4 rotates and the main shaft begins to work, and the centrifugal blood pump begins to pump blood. Simultaneously, drive motor I25 drives the steering gear assembly 6, generating blood pulsation. The output shaft of drive motor I25, equipped with rotating gears, meshes with the input internal gear ring 19, which in turn rotates the output internal gear ring 11 via intermediate gears I21 and II22. The input internal gear ring 19 meshes with intermediate gear II22 and double gear II17, causing intermediate gear II22 to rotate in the same direction as the input internal gear ring 19. This results in intermediate gear I21 rotating in the opposite direction to the input internal gear ring 19, causing the output internal gear ring 11 to rotate in different directions. Since double gear I12 meshes with the output internal gear ring 11, the double gear... Gear I12 rotates in the same direction as the output internal gear ring 11. When the half gear of the double gear I12 meshes with the steering gear 8, it directly outputs rotation. The input internal gear ring 19 drives the double gear II17 to rotate in the same direction. At this time, the double gear II17 rotates in the opposite direction to the double gear I12. When the half gear of the double gear II17 meshes with the steering gear 8, it outputs rotation. In one rotation cycle, the half gears of the double gear II17 and the double gear I12 only mesh with the steering gear 8 for half a cycle. Thus, the steering gear 8 can rotate in both clockwise and counterclockwise directions in one rotation cycle. The steering gear 8 transmits the rotation to the bevel gear I27 on the blade shank 51 through the bevel gear II28, so that the blade angle changes alternately in clockwise and counterclockwise directions in one rotation cycle. The flexible material 52 at the bottom of the blade can deform to a certain extent to meet the angle change of the blade.

[0056] In summary, the steering gear assembly 6, in conjunction with the blade 5, can achieve pulsation of blood flow. By adjusting the flow rate through changes in the blade angle, the pulsation characteristics of blood are ultimately realized.

[0057] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope. All such changes and modifications fall within the scope of the present invention as claimed, which is defined by the appended claims and their equivalents.

Claims

1. A centrifugal blood pump that outputs pulsating flow rate at constant speed, characterized in that: It includes a pump casing (1), an impeller (2), a pump body (3), an impeller (4), blades (5), and a steering gear assembly (6). The pump body (3) is located below the pump casing (1), and the impeller (2) is rotatably mounted between the bottom of the pump casing (1) and the pump body (3). The pump body (3) is equipped with a steering gear assembly (6), a drive motor II (15) and a drive motor I (25). An impeller (4) is located in the center of the inner cavity of the pump casing (1). Several blades (5) are evenly arranged around the circumference of the impeller (4). A bevel gear I (27) is located at the root of the blades (5). The drive motor II (15) is used to drive the impeller (4) to rotate, thereby driving the blades (5) to rotate. The drive motor I (25) is used to drive the steering gear assembly (6) to work. The steering gear assembly (6) includes a housing (7) and two output internal gear rings (11) and an input internal gear ring (19) that are axially rotatable in the housing (7) with opposite rotation directions. A steering gear (8) is provided in the middle of the housing (7). The steering gear (8) is sleeved on the rotating main shaft of the impeller (4). One end of the steering gear (8) meshes with the bevel gear I (27) through the bevel gear II (28) inside the impeller. The blade (5) is deflected by rotating the two meshing bevel gears. The spur gear at the other end of the steering gear (8) is connected to an alternating steering mechanism so that the deflection angle of the blade (5) changes alternately in the forward and reverse directions.

2. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 1, characterized in that: The inner ring of the input internal gear ring (19) meshes with the rotating gear connected to the motor shaft of the drive motor I (25). An intermediate gear I (21) and an intermediate gear II (22) are provided between the output internal gear ring (11) and the input internal gear ring (19). The intermediate gear II (22) meshes with the intermediate gear I (21) and the input internal gear ring (19) respectively. The intermediate gear I (21) meshes with the output internal gear ring (11). The input internal gear ring (19) is driven to rotate by the drive motor I (25), and then transferred to the output internal gear ring (11) through the intermediate gear II (22) and the intermediate gear I (21), so that the input internal gear ring (19) and the output internal gear ring (11) rotate in opposite directions.

3. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 2, characterized in that: The alternating steering mechanism includes a double gear I (12) and a double gear II (17), each of which includes a full gear and a half gear. The two half gears rotate in opposite directions. Both the double gear I (12) and the double gear II (17) mesh with the middle steering gear (8). The steering gear (8) is isolated from the rotating shaft of the impeller (4) by a sleeve (20), and the spur gear at one end of the steering gear (8) meshes with the half gears of the double gear I (12) and the double gear II (17), respectively. The full gear of the double gear I (12) meshes with the output internal gear ring (11), and the full gear of the double gear II (17) meshes with the input internal gear ring (19).

4. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 3, characterized in that: A baffle I (10) is provided above the output internal gear ring (11), a baffle II (18) is provided at the bottom of the input internal gear ring (19), and two bosses for fixing the baffle I (10) and the baffle II (18) are provided on the housing (7); The double gear II (17) is positioned by the hole on the baffle II (18) and is axially fixed by the boss on the first shaft (9); the double gear I (12) is positioned by the hole on the baffle I (10) and is axially fixed by the boss on the second shaft (13). The intermediate gear I (21) is positioned and connected to the holes on the baffle II (18) and baffle I (10) respectively through the third shaft (23), and the intermediate gear II (22) is positioned and connected to the holes on the baffle II (18) and baffle I (10) through the fourth shaft (24).

5. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 1, characterized in that: A bearing (16) is also installed on the rotating main shaft of the impeller (4). The outer edge of the bearing (16) is close to the hollow wall at the bottom of the box (7). One end of the bearing (16) is installed close to the drive motor II (15), and the other end is fixed by the baffle II (18).

6. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 1, characterized in that: The bottom of the pump casing (1) is positioned and installed with the raised step of the impeller (2) through a positioning groove.

7. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 1, characterized in that: The blade (5) is recessed at the bottom in the fixed groove of the impeller. The blade (5) includes a blade body (51). A stalk (50) is provided at the root of the blade body (51). A bevel gear I (27) provided at the front end of the stalk meshes with a bevel gear II inside the impeller (4) through a hole in the circumference. A flexible material (52) is provided below the blade body (51). One end of the flexible material (52) is wrapped around the blade (5), and the other end is installed in the gap in the groove of the impeller (2).

8. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 1, characterized in that: The drive motor I (25) is mounted on the bottom plate of the housing (7) and is fixed by a ring of steel protruding from the bottom plate.

9. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 1, characterized in that: The drive motor II (15) is fixed at the bottom of the pump body (3). The output shaft of the drive motor II (15) cooperates with the rotating main shaft of the impeller (4) through the crescent groove (151) to drive the main shaft to rotate.

10. A centrifugal blood pump with constant speed and pulsating flow rate according to claim 1 or 9, characterized in that: The drive motor II (15) includes several circumferentially symmetrical threaded holes (152) and several symmetrical countersunk holes (150). The bottom of the pump body (3) is provided with threaded holes. The drive motor II (15) is fixed to the bottom of the pump body (3) by screw I (14). The bottom of the housing (7) is provided with holes. The housing (7) is installed on the drive motor II (15) by screw II (26).

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