CN207708246U - Microminiature micro-centrifugal blood pump with self-regulation blade - Google Patents

Abstract

The utility model discloses a miniature centrifugal blood pump with self-regulating blades. The existing technology cannot well control the boundary layer thickness, secondary flow and eddy current noise in the micro blood centrifugal pump. The suction surface of each first-stage blade of the utility model is provided with a small wing; each second-stage blade and a swing blade are fixed by a cylindrical rod, and the cylindrical rod and the front end cover form a rotating pair; the inner side of the active ring is provided with an arc The gear at the output end of the control box meshes with the arc-shaped rack; the hinge ends of each connecting rod and the active ring are evenly distributed along the circumferential direction of the active ring; a division point is set on the profile line of each swing blade as the The hinged end of the swing blade and the corresponding connecting rod; the larger the section area of the volute, the closer the division point on the profile line of the swing blade is to the trailing edge of the swing blade. The secondary blades of the utility model have different attack angles, which solves the need for adjustable blade installation angles under the conditions of different flow parameters such as different speeds of blood on different volute sections.

Description

Tiny centrifugal blood pump with self-adjusting vanes

technical field

The utility model belongs to the field of fluid transportation, and relates to a miniature centrifugal blood pump with automatic blade adjustment, low noise, and low damage to blood cells, in particular to an automatic adjustment blade according to a control box and a connecting rod system, and an impeller blade with a suction surface. Micro centrifugal blood pump with winglet structure.

Background technique

Pump is a kind of general-purpose machinery with a wide range of applications. It plays a huge role in human production and life. Pumps of different types and sizes are constantly being manufactured and used in various industries according to new application needs. middle. According to the different characteristic scales, pumps can be roughly divided into the following categories: conventional pumps, micro pumps and micro pumps. Among them, the characteristic scale range of micro-small pumps is roughly 1-50 mm, while the characteristic lengths of micro-pumps and conventional pumps are respectively below 1 mm and above 50 mm.

Due to its special size range, micro pumps show good application prospects, such as cooling systems for micro motors and electronic equipment including computer CPUs, pipeline pumps, temperature control systems for fuel cells, and the most widely used medical pumps. equipment etc.

Considering the high viscosity of blood and the easy rupture of blood cells in blood transport, how to design a micro centrifugal pump with low flow shear force and stable internal flow is very important. However, in addition to the particularity of the transported liquid, the flow in the micro centrifugal pump is very complicated, mainly reflected in: 1) the three-dimensionality of the flow; 2) the viscosity of the fluid; 3) the unsteadiness of the flow. Because of the particularity of the viscosity and transport requirements of transporting blood, the viscosity does not only affect the blade wake vortex formed at the blade outlet edge to satisfy the Kutta-Zhukovsky condition. Due to the viscosity, there will be a viscous boundary layer on the surface of the blade and the surface of the ring wall channel, and there will be a strong interaction between them and the main flow, resulting in the phenomenon of "secondary flow". Secondary flow is the main source of increased loss and decreased efficiency of micro centrifugal pumps. At the same time, secondary flow and vortex breakage are the main sources of noise in centrifugal pumps.

At the same time, the heart transports blood through diastole and contraction, and the output is pulsating flow (flow, pressure pulsation). If the rotating blood pump simulates the natural heart of the human body to output the pulsating flow (flow rate, pressure pulsation), it will help the recovery of the human body after cardiac surgery. However, due to the periodic variable speed of the rotating blood pump, the flow parameters (flow, pressure, etc.) of the blood in the cycle change with time, resulting in the speed, pressure, and shear force inside the blood pump changing all the time. The flow state and the particularity of blood (blood cells are easily broken and blood is highly viscous) aggravate the formation of vortex and the damage of shear force to blood cells. The installation angle of the traditional fixed blade is fixed, and the change of the main direction of fluid flow and the change of various parameters caused by the change of the speed of the variable speed centrifugal pump cannot be responded to in time, and the best blade installation angle required for better flow cannot be provided. Higher efficiency is always achieved at any speed, and vortex is generated, which aggravates eddy current noise. At the same time, for the volute whose cross-sectional area is constantly changing, the flow velocity and other parameters on different cross-sections are different. At this time, it is more appropriate to require different blade angles of attack. This requires that the adjustable blades of variable speed pumps need to be adjusted according to different Different blades have different angular change rates.

To sum up, for the variable speed centrifugal blood pump, in order to design and optimize a micro centrifugal blood pump with high efficiency, low noise and low damage to blood cells, it is necessary to control and reduce the secondary flow, prevent vortex shedding or Control the formation of the vortex, and have automatic adjustable blades that can find the corresponding optimal blade installation angle for various changing parameters in variable speed motion.

Contents of the invention

The purpose of this utility model is to solve the situation that the existing technology cannot well control the boundary layer thickness, secondary flow and eddy current noise in the micro-small blood centrifugal pump, and it is impossible to obtain adjustable blade installation angle blades for variable speed centrifugal pumps, and provide two The micro-centrifugal pump of the first-stage vane, specifically, the suction surface of the first-stage vane has a winglet structure, and the second-stage impeller is a micro-small centrifugal blood pump with self-adjusting installation angle vanes.

The utility model comprises a front end cover, a rear end cover, a first-stage impeller and a second-stage adjustable blade impeller; the front end cover, the rear end cover, the first-stage impeller and the second-stage adjustable blade impeller are coaxially arranged. The suction surface of each first-stage blade of the first-stage impeller is provided with a small wing at the center of the height direction, and the trailing edge of the small wing is flush with the trailing edge of the first-stage impeller; the height direction of the small wing is perpendicular to the height direction of the first-stage blade Setting; the profile length of the winglet is 10% to 15% of the profile length of the first-stage blade, and the profile lengths of the winglets on each primary blade are equal; the cross-section of the winglet is rounded at all three corners isosceles triangle, the fillet radius is 0.1~0.2 of the height of the isosceles triangle; the angle at the leading edge of the isosceles triangle is the minimum angle, and the minimum angle is 30°; the leading edge of the winglet has an inclination angle of 30° relative to the height direction of the winglet ; The thickness of the primary blade is 0.3-0.4 of the height of the trailing edge of the winglet.

The two-stage adjustable vane impeller includes a driving ring, a connecting rod, a swing vane, a cylindrical rod, a second-stage vane and a control box. Z ₁ second-stage blade is arranged along the circumference of the second-stage adjustable-blade impeller, Z ₁ =n*Z, where n is 1, 2 or 3, and Z is the number of first-stage blades of the first-stage impeller. Each secondary blade is fixedly connected to a swinging blade through a cylindrical rod, and the axis of the cylindrical rod is located on the centering surface of the secondary blade and the swinging blade; the cylindrical rod and the round hole opened in the front end cover form a rotating pair, and the swinging blade is located at the front end Outside the cover, the secondary vanes are located inside the front end cover. Each oscillating blade is hinged to one end of a connecting rod, and the other ends of all connecting rods are hinged to the circular ring; the inner side of the active circular ring is provided with an arc-shaped rack, and the gear at the output end of the control box meshes with the arc-shaped rack ; The central angle corresponding to the arc-shaped rack is 30°-60°. The cylindrical rod is provided with a labyrinth sealing structure.

The hinged ends of each connecting rod and the active ring are evenly distributed along the circumferential direction of the active ring; the line connecting the center of the ring and the most convex point of the volute tongue on the volute is the zero-degree line, and the direction in which the cross-sectional area of the volute gradually increases is the direction in which the angle increases. Positive direction; the volute is composed of a front end cover and a rear end cover; the cylindrical rods are arranged at an angle of -15° to 25° away from the zero-degree line, and the position of the first cylindrical rod is 45° from the zero-degree line, and the rest of the cylindrical rods are kept away from the zero-degree line The zero degree line -15°～45° is evenly distributed along the circumference of the two-stage adjustable blade impeller. A division point is set on the profile line of each swing blade as the hinge end of the swing blade and the corresponding connecting rod. The greater the volute cross-sectional area, the closer the division point on the profile line of the swing blade is to the trailing edge of the swing blade.

A gasket is provided between the front end cover and the rear end cover, and the front end cover and the rear end cover are connected by bolts.

The cavity between the front end cover and the end surface of the primary impeller is a pressurized water chamber, which is the inlet port of blood.

The inner diameter of the active ring is 1.2 times the radius of the entrance of the front cover.

The distance L between the center of rotation of the first-stage impeller and the central axis of the cylindrical rod satisfies the following formula:

LR ₁ -0.5*L ₂ =0.05R ₁ ;

In the formula, L ₂ is the profile length of the second-stage blade, and R ₁ is the radius of the first-stage impeller.

The labyrinth sealing structure includes two annular groove groups; the annular groove group is composed of 6 to 8 annular grooves arranged equidistantly, and the groove width of the annular grooves is equal to the distance between adjacent annular grooves.

The control box is output with a rotational speed function of the gear at the output end rotating at different speeds.

The beneficial effects of the utility model:

The utility model is equipped with an isosceles triangular winglet structure at the outlet end of the first-stage fixed blade impeller, which can well control the radial flow caused by the imbalance of fluid pressure and centrifugal force, and can also cut and comb the large channel vortex , to effectively separate and guide the viscous fluid in the flow channel, making the flow an ideal flow state, reducing the wake loss and eddy current noise of the centrifugal pump. Controlling the size of a pair of channel vortices in the blade flow channel also controls the secondary flow of radial motion, reduces the unevenness of velocity, reduces the loss of jet wake, suppresses the vortex strength and flow loss at the end of the blade channel and controls Vortex shedding.

The two-stage adjustable vane impeller, in view of the periodic changes in speed and pressure caused by the variable speed during the operation of the blood centrifugal pump, can choose the appropriate vane angle of attack according to the change of the incoming blood, and weaken the "jet flow" at the outlet of the first-stage impeller. -Wake", weaken the large eddy current that appears at the outlet end, and divide and sort out the blood again, sort the large vortex into a small vortex, and improve the internal flow of the blood pump. The two-stage adjustable guide vane is similar to a vane diffuser for the whole blood pump, which converts the kinetic energy of the fluid into useful pressure energy, and further increases the head of the blood pump, so that the speed of the centrifugal pump can be appropriately reduced under the same head, and then The centrifugal force received by the blood is reduced, and the centrifugal force received by the blood cells in the blood is reduced.

The control box inputs the rotation speed function of the gear at the output end in advance, and controls the gear at the output end according to the change of the function to ensure that the initial angular momentum of the adjustable blade on the active ring is consistent. Different lengths of connecting rods make The rate of change of the adjustable blades at different circumferential positions is different, which further leads to different adjustable blades having different blade rotations, obtaining different blade angles of attack, and solving different speeds of blood on different volute sections, etc. The demand for the installation angle of the adjustable blade under the condition of different flow parameters. It satisfies the different requirements of the adjustable vanes at different circumferential positions on the adjustable vane installation angle at different speeds, reduces the friction loss of blood, and at the same time effectively separates and guides the viscous fluid in the flow channel, resulting in an ideal flow state. The noise caused by vortex shedding and vortex breaking is reduced. At the same time, the eddy current strength of the centrifugal pump is reduced, the dynamic pressure is further reduced, and the static pressure is increased, thereby obtaining higher efficiency.

Description of drawings

Fig. 1 is a structural perspective view of the utility model;

Fig. 2 is a structural diagram of the first stage impeller of the present utility model;

Fig. 3 is a structural diagram of a first-stage blade of the utility model;

Fig. 4 is a schematic diagram of the sealing method of the cylindrical rod and the front end cover of the present invention;

Figure 5 is an enlarged view of A-A of Figure 4;

Fig. 6 is the perspective view of the secondary adjustable blade impeller in the utility model;

Fig. 7 is the two-dimensional schematic diagram of the two-stage adjustable blade impeller in the utility model;

Fig. 8 is a schematic diagram of the position distribution of each swing blade and the hinged end of the corresponding swing blade in the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment the utility model is further described.

As shown in Figure 1, a micro centrifugal blood pump with self-adjusting blades includes a front end cover 1, a rear end cover 2, a primary impeller 3 and a secondary adjustable blade impeller 5; A gasket 4 is provided, and the front end cover 1 and the rear end cover 2 are connected by bolts; the front end cover 1, the rear end cover 2, the primary impeller 3 and the secondary adjustable blade impeller 5 are coaxially arranged. The cavity between the front end cover 1 and the end surface of the first-stage impeller 3 is a pressurized water chamber, which is the inlet port of blood; the number of first-stage blades of the first-stage impeller 3 is Z=5.

As shown in Figures 2 and 3, the suction surface of each first-stage blade of the first-stage impeller 3 is provided with a small wing 3-1 at the center of the height direction, and the trailing edge of the small wing is flush with the trailing edge of the first-stage impeller 3; The height direction of the winglet is set perpendicular to the height direction of the first-stage blade; the profile length of the winglet 3-1 is 10% to 15% of the profile length of the primary blade, and the profile length of the winglet on each stage blade Equal; the cross section of the winglet is an isosceles triangle with all three corners rounded, and the radius of the fillet is 0.1 to 0.2 of the height of the isosceles triangle; the angle at the leading edge of the isosceles triangle is the smallest angle, and the minimum angle is 30° ; The leading edge of the winglet has an inclination angle δ of 30° relative to the height of the winglet; the thickness b2 of the primary blade is 0.3-0.4 of the height b1 of the trailing edge of the winglet. Adding a winglet structure to the outlet of the impeller channel with large flow instability can improve the flow condition at the impeller, suppress the vortex structure at the outlet of the impeller channel, and suppress the "jet-wake" phenomenon at the outlet of the impeller channel. Reduced eddy noise caused by blade wakes.

As shown in Figures 1, 4, 6 and 7, the two-stage adjustable vane impeller 5 includes a driving ring 9, a connecting rod 8, a swing vane 7, a cylindrical rod 6, a second-stage vane 10 and a control box 11. Z ₁ second-stage blade is arranged along the circumferential direction of the second-stage adjustable blade impeller 5, Z ₁ =n*Z, n is 1, 2 or 3, and n=1 in this embodiment. Each secondary blade and a swinging blade are fixedly connected by a cylindrical rod, and the axis of the cylindrical rod is located on the centering surface of the secondary blade and the swinging blade; The front end cover 1 is outside, and the secondary blade is located inside the front end cover 1 . Each swing blade is hinged to one end of a connecting rod, and the other ends of all connecting rods are hinged to the ring; the inner diameter of the active ring is 1.2 times the radius of the entrance of the front cover 1 . An arc-shaped rack 9-1 is arranged inside the active ring, and the gear 11-1 at the output end of the control box meshes with the arc-shaped rack; the central angle θ corresponding to the arc-shaped rack is 30° to 60°. Take 30° in the example. The limitation of the central angle corresponding to the arc-shaped rack, thereby limiting the limit position of the secondary blade. Because the angle of attack of the second-stage blade can be adjusted, this embodiment ensures that the distance L between the rotation center of the first-stage impeller and the central axis of the cylindrical rod satisfies the following formula to ensure that the second-stage blade is adjacent to but not in contact with the first-stage blade:

LR ₁ -0.5*L ₂ =0.05R ₁ ;

In the formula, L ₂ is the profile length of the second-stage blade, and R ₁ is the radius of the first-stage impeller.

As shown in Figure 5, the cylindrical rod is provided with a labyrinth-shaped sealing structure, which ensures that the viscous blood does not leak. The labyrinth sealing structure includes two ring groove groups; the ring groove group is composed of 6 to 8 ring grooves arranged equidistantly, and the groove width of the ring grooves is equal to the distance between adjacent ring grooves.

As shown in FIG. 8 , each connecting rod 8 and the hinged end 8 - 1 of the driving ring are evenly distributed along the circumferential direction of the driving ring. Each connecting rod 8 is related to the cross-sectional area of the corresponding volute (the front end cover 1 and the rear end cover 2 form the volute) at the position of the hinged end 8-2 of the corresponding piece of swing blade 7. The position of the hinged end 8-2 corresponding to a swing blade 7 is as follows:

1) Take the line connecting the center of the circular ring and the most convex point of the volute tongue on the volute as the zero-degree line, and take the direction in which the cross-sectional area of the volute gradually increases as the positive direction of the angle increase. Because the flow is unstable at -10° to 20° near the volute tongue, the cylindrical rods are arranged at an angle of -15° to 25° away from the zero degree line. In this embodiment, the number of cylindrical rods is Z ₁ =5, 45° is taken as the position of the first cylindrical rod, and the rest of the cylindrical rods are evenly distributed along the 5th circumferential direction of the two-stage adjustable blade impeller, avoiding the zero degree line -15°-45°.

2) Taking the largest cross-sectional area among the cross-sectional areas of the volute passing through the central axes of each cylindrical rod as the reference area, the calculated ratio of the cross-sectional area of the volute passing through the central axes of each cylindrical rod to the reference area in this embodiment is 61 %, 82%, 84%, 86%, and 100%.

3) Along the direction from the leading edge to the trailing edge of the swinging blade, set a split point on the profile line of each swinging blade according to the cross-sectional area ratio corresponding to the cylindrical rod at the position, as the hinge end of the swinging blade 7 and the corresponding connecting rod 8 8-2, that is, the greater the cross-sectional area of the volute, the closer the division point on the profile line of the swing blade is to the trailing edge of the swing blade.

The utility model inputs the rotation speed function of the gear at the output end to the control box, and controls the gear at the output end according to the change of the function, so as to ensure that the initial angular momentum of the adjustable blade on the active ring is consistent. The length of the connecting rod makes the rate of change of the adjustable blades at different circumferential positions different, which further leads to different blade rotations for different adjustable blades, and obtains different blade angles of attack. The problem of different flow velocities caused by the volute cross-sectional area, that is, the rotation angle of each blade is different for different volute cross-sectional flow velocities.

At the same time, the two-stage vanes can guide the flow of the front and rear pump chambers of the pump body, and guide the instability of the flow in the front and rear chambers caused by the variable speed flow. With the guide of the blades As a result, the fluid in the front pump chamber and the rear pump chamber of the centrifugal pump can have a diversion direction in advance to sort out the viscous fluid and improve the flow conditions of the front and rear pump chambers.

Provide the second-stage impeller as an impeller with adjustable installation angle blades. For the changing speed, pressure and shear force of the centrifugal pump when the speed changes, the installation angle of the second-stage blades can be changed in a certain range in time to make the flow from the first-stage blades The blood converts kinetic energy into potential energy under the guidance of the second-stage blades, so that the centrifugal pump can always achieve the most favorable efficiency at any speed. flow conditions and reduce eddy current noise.

Claims (7)

1. A microcentrifugal blood pump with self-adjusting blades, comprising a front end cover, a rear end cover, a first-stage impeller and a second-stage adjustable blade impeller, characterized in that: the front end cover, rear end cover, first-stage impeller and The two-stage adjustable blade impellers are all set coaxially; the suction surface of each first-stage blade of the first-stage impeller is provided with a small wing at the center of the height direction, and the trailing edge of the small wing is flush with the trailing edge of the first-stage impeller; The height direction of the blade is perpendicular to the height direction of the first-stage blade; the profile length of the small wing is 10% to 15% of the profile length of the primary blade, and the profile length of the small wing on each primary blade is equal; The cross-section of the wing is an isosceles triangle with three corners rounded, and the radius of the fillet is 0.1 to 0.2 of the height of the isosceles triangle; the angle of the isosceles triangle at the leading edge is the minimum angle, and the minimum angle is 30°; the winglet The leading edge has an inclination angle of 30° relative to the height of the winglet; the thickness of the primary blade is 0.3-0.4 of the height of the trailing edge of the winglet; The two-stage adjustable vane impeller includes a driving ring, a connecting rod, a swing vane, a cylindrical rod, a second-stage vane and a control box; Z ₁ second-stage vanes are arranged circumferentially along the two-stage adjustable vane impeller, and Z ₁ = n*Z, n takes 1, 2 or 3, Z is the number of first-stage blades of the first-stage impeller; each second-stage blade is fixedly connected to a swing blade through a cylindrical rod, and the axis of the cylindrical rod is located between the second-stage blade and the swing blade The centering surface of the centering surface; the circular hole opened by the cylindrical rod and the front end cover constitutes a rotating pair, the swing blade is located outside the front end cover, and the secondary blade is located inside the front end cover; each swing blade is hinged with one end of a connecting rod, and all connecting rods The other end of each is hinged with the circular ring; the inner side of the active circular ring is provided with an arc-shaped rack, and the gear at the output end of the control box meshes with the arc-shaped rack; the corresponding central angle of the arc-shaped rack is 30°～60° ; The cylindrical rod is provided with a labyrinth sealing structure; The hinged ends of each connecting rod and the active ring are evenly distributed along the circumferential direction of the active ring; the line connecting the center of the ring and the most convex point of the volute tongue on the volute is the zero-degree line, and the direction in which the cross-sectional area of the volute gradually increases is the direction in which the angle increases. Positive direction; the volute is composed of a front end cover and a rear end cover; the cylindrical rods are arranged at an angle of -15° to 25° away from the zero-degree line, and the position of the first cylindrical rod is 45° from the zero-degree line, and the rest of the cylindrical rods are kept away from the zero-degree line The zero degree line -15°～45° is evenly distributed along the circumference of the two-stage adjustable blade impeller; a dividing point is set on the profile line of each swing blade as the hinge end of the swing blade and the corresponding connecting rod; The split point on the profile line of the swing blade at the larger position is closer to the trailing edge of the swing blade. 2. The micro centrifugal blood pump with self-adjusting blades according to claim 1, characterized in that: a gasket is provided between the front end cover and the rear end cover, and the front end cover and the rear end cover are connected by bolts . 3. The micro-centrifugal blood pump with self-adjusting blades according to claim 1, characterized in that: the cavity between the front end cover and the end face of the first-stage impeller is a pressurized water chamber, and the pressurized water chamber is the blood chamber. import side. 4. The micro centrifugal blood pump with self-adjusting vanes according to claim 1, wherein the inner diameter of the active ring is 1.2 times the radius of the inlet of the front cover. 5. The miniature centrifugal blood pump with self-adjusting blades according to claim 1, characterized in that: the distance L between the rotation center of the first-stage impeller and the central axis of the cylindrical rod satisfies the following formula: LR ₁ -0.5*L ₂ =0.05R ₁ ; In the formula, L ₂ is the profile length of the second-stage blade, and R ₁ is the radius of the first-stage impeller. 6. The miniature centrifugal blood pump with self-adjusting blades according to claim 1, characterized in that: the labyrinth-shaped sealing structure includes two annular groove groups; the annular groove groups consist of 6 to 8 equally spaced It is composed of annular grooves, and the groove width of the annular grooves is equal to the distance between adjacent annular grooves. 7. The miniature centrifugal blood pump with self-adjusting blades according to claim 1, characterized in that: said control box is provided with a rotational speed function of the gear at the output end rotating at different speeds.