A test bench for displaying the full flow field of an axial flow blood pump and a flow field observation method

Abstract

The present invention provides a test bench for displaying the full flow field of an axial blood pump, characterized in that: an axial blood pump fixing device and an axial blood pump driving device are arranged on the test bench, the tested axial blood pump is arranged on the axial blood pump fixing device, the axial blood pump driving device is a non-contact magnetic coupling driving device, which includes an active magnet and a driving motor, the driving motor is connected to the active magnet, the active magnet and the passive magnet of the rotor impeller in the axial blood pump are placed in parallel to form a non-contact magnetic coupling driving relationship, so that the active magnet rotates, thereby driving the passive magnet of the rotor impeller in the axial blood pump arranged on the axial blood pump fixing device to rotate, and matching this, at least a part of the pump housing of the axial blood pump is made of transparent material. The panoramic view of the flow field of the axial blood pump can be observed through the test bench of the present invention. The present invention also provides an observation method.

Description

Technical Field

[0001] The invention relates to the technical field of medical devices, and in particular to a test bench for displaying the full flow field of an axial flow blood pump. A method for observing the flow field of the axial flow blood pump is also provided. Background Art

[0002] Axial flow blood pump is a type of ventricular assist device, which partially assists or completely replaces the heart's pumping function and maintains the normal circulation of human blood. At present, traditional axial flow blood pumps use transmission motors as the driving system, and the full-ring coil is sleeved outside the pump housing to drive the rotor impeller to rotate. Due to the obstruction of the coil, the blood flow in the pump, especially in the rotor impeller area, cannot be observed by particle imaging velocimetry (PIV) and other methods. The blood flow in the axial flow blood pump is closely related to the efficiency, hemolysis and thrombosis of the blood pump, and is an important observation data for evaluating the structural design and flow field optimization of the blood pump. However, due to the obstruction of the drive coil and the opacity of the pump housing material, it is still difficult to observe the full flow field inside the axial flow blood pump. In order to observe the flow field conditions in a larger range within the axial flow blood pump, the current test bench used for PIV display of the flow field within the blood pump places the rotor impeller of the blood pump into a cavity made of transparent material, connects the shaft of the motor and the shaft of the rotor impeller to directly drive the rotor impeller to rotate. The problem with this is that the presence of the motor shaft in the flow field and the resulting modification or cancellation of the front and rear guide vane structures of the axial flow blood pump make the measured flow field in the axial flow blood pump inconsistent with the actual operation of the axial flow blood pump, and the credibility of the test results is greatly reduced. Summary of the invention

[0003] The purpose of the present invention is to solve the defect that in the flow field observation test inside the axial flow blood pump (especially the PIV flow field display test), the traditional axial flow blood pump driven by a DC brushless motor obscures the internal structure of the blood pump due to the presence of the motor coil, and the flow conditions inside the blood pump, especially the rotor impeller area, cannot be observed by the naked eye or test. The present invention overcomes the problem of difficulty in observing the flow field inside the axial flow blood pump and provides an axial flow blood pump flow field test bench in which the full flow field flowing inside the pump can be completely observed and recorded by the naked eye or a charge coupled device (CCD) camera for PIV testing.

[0004] Another object of the present invention is to provide a method for observing the flow field inside an axial flow blood pump using the above-mentioned test bench.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A test bench for displaying the full flow field of an axial blood pump is provided. An axial blood pump fixing device and an axial blood pump driving device are arranged on the test bench. The axial blood pump to be tested is arranged on the axial blood pump fixing device. The axial blood pump driving device is a non-contact magnetic coupling driving device, including an active magnet and a driving motor. The driving motor is connected to the active magnet. The active magnet and the passive magnet of the rotor impeller in the axial blood pump are placed in parallel to form a non-contact magnetic coupling driving relationship, so that the active magnet rotates, thereby driving the passive magnet of the rotor impeller in the axial blood pump to rotate. Matching this, at least a part of the pump housing of the axial blood pump is made of transparent material.

[0007] Preferably, the entire pump housing of the axial flow blood pump is made of transparent material.

[0008] The present invention uses the above-mentioned test bench to replace the motor coil with a non-contact magnetic coupling drive device to drive the rotor impeller of the axial flow blood pump to rotate. In addition, the pump casing of the axial flow blood pump is made of transparent materials such as acrylic or quartz glass, so that the entire flow field flowing in the pump can be visualized.

[0009] Preferably, the active magnet in the axial flow blood pump driving device and the passive magnet in the axial flow blood pump are both cylindrical and radially magnetized permanent magnets, and the two poles of the permanent magnets are located on two opposite sides of the cylindrical permanent magnet.

[0010] The structure of the active magnet is as follows: it includes an iron core shaft and a permanent magnet. The permanent magnet is provided with an axial through hole. The iron core shaft, namely the rotating shaft, passes through the axial through hole and is fixed together with the permanent magnet.

[0011] As an embodiment, when the permanent magnet body length of the passive magnet is 20 mm and the permanent magnet diameter length is 8 mm, the permanent magnet body length of the active magnet is 20 mm and the permanent magnet diameter length is 10.7 mm.

[0012] The axial distance between the two mounting holes of the active magnet and the passive magnet on the test bench is less than 50-60 mm.

[0013] The motor is a DC motor.

[0014] The voltage of the motor is adjustable.

[0015] As an embodiment, the voltage of the motor is adjustable between 0-24V, and the maximum output power is 30V.

[0016] Specifically, the structure of the test bench may be:

[0017] The output shaft of the driving motor is arranged vertically upward, a bottom plate is arranged at the upper end of the driving motor, and the output shaft of the driving motor is located in the middle of the bottom plate;

[0018] A test frame is arranged above the bottom plate, on which an active magnet is rotatably arranged, and the active magnet is connected to the output shaft of the drive motor; a bearing support is also arranged on the test frame, on which the axial blood pump is arranged, so that the axial blood pump is arranged parallel to the axis of the active magnet, and a set distance is arranged between the bearing support of the axial blood pump and the active magnet, and the set distance enables the active magnet to magnetically couple and drive the passive magnet in the axial blood pump on the bearing support of the axial blood pump to rotate;

[0019] The inlet and outlet of the axial flow blood pump are connected to a circulation loop.

[0020] The test frame includes an upper baffle, a lower baffle and four screws. The upper baffle, the lower baffle and the four corners of the bottom plate are provided with corresponding upper and lower through holes. The four screws are inserted into the through holes at the four corners and matched with nuts so that the upper baffle, the lower baffle and the bottom plate are fixed at set intervals. The upper baffle and the lower baffle are provided with corresponding upper and lower mounting holes, and the bearing supports of the active magnet and the axial blood pump are provided in the mounting holes, so that the active magnet and the axial blood pump are arranged in parallel between the lower baffle and the upper baffle.

[0021] The rotating shaft of the active magnet extends downward from the lower baffle plate and is fixed to the output shaft of the driving motor extending upward through a coupling.

[0022] The method of observing the flow field in the axial blood pump through the aforementioned test bench is:

[0023] Sprinkle fluorescent particles into the test fluid and start the drive motor;

[0024] Laser can directly irradiate the fluorescent particles in the flow field of the transparent axial blood pump from any direction.

[0025] The CCD camera located perpendicular to the laser can directly capture the flow field inside the transparent axial flow blood pump. Therefore, this test bench can be used for PIV display of the flow field inside the blood pump and other tests.

[0026] The test bench is used to observe the flow field inside the axial blood pump. Not only can the flow field in the area near the inlet and outlet of the axial blood pump be observed, but also the flow field in the rotor blade area which is traditionally blocked by the coil and cannot be observed.

[0027] The cylindrical active magnet in the axial flow blood pump driving device and the passive magnet in the axial flow blood pump have a generatrix in the middle of the outer side of half the cylinder, which is the pole line A. The pole line A forms a pole plane with the axis of the magnet. At the beginning of the test, the angle between the pole planes of the same magnetic poles of the active magnet and the passive magnet is the initial relative angle, which is 60° to 100°.

[0028] When the rotation speed of the impeller of the axial blood pump needs to be adjusted, the rotation speed of the active magnet is adjusted by adjusting the voltage of the motor, thereby adjusting the rotation speed of the axial blood pump.

[0029] The present invention adopts a designed flow field test bench, wherein the shaft of a motor is used to drive the active magnet to rotate, the motor shaft and the active magnet are connected by a coupling, the active magnet is installed between an upper baffle and a lower baffle, a bottom plate is installed on the motor, the bottom plate is connected to the lower baffle by a screw, and the lower baffle is connected to the upper baffle by a screw.

[0030] During the test, the transparent axial blood pump in the circulation loop is installed in the mounting holes of the upper baffle and the lower baffle in a direction parallel to the active magnet. The magnetic field generated by the rotating active magnet acts on the passive magnet in the rotor impeller to make it rotate at the same speed as the active magnet, thereby driving the rotor impeller of the transparent axial blood pump to rotate, so that the flow field in the transparent axial blood pump can be fully observed. Because the flow of the fluid in the transparent axial blood pump can be observed from most directions, if fluorescent particles are sprinkled into the test fluid, the laser can directly irradiate the fluorescent particles in the flow field of the transparent axial blood pump from any direction, and the CCD camera located at a perpendicular position to the laser can directly capture the flow field in the transparent axial blood pump, so this test bench can be used for PIV display of the flow field in the blood pump.

[0031] When observing the flow field in the axial blood pump through the test bench, the transmission efficiency can be improved by adjusting the initial relative angle between the active and passive magnets, and the rotation speed of the impeller can be changed by adjusting the voltage of the DC motor.

[0032] The test bench for displaying the full flow field of an axial blood pump provided by the present invention adopts magnetic coupling drive to replace the motor coil drive of a traditional axial blood pump. The active magnet of the magnetic coupling drive has no contact with the axial blood pump and is at a certain distance. In addition, the pump housing of the axial blood pump is made transparent. Therefore, there is no external shielding of the flow field in the pump, and the flow field in the entire pump can be observed by the naked eye or a CCD camera. The method provided by the present invention can conveniently observe the flow field in the pump, improve the transmission efficiency, and facilitate the adjustment of the impeller speed.

[0033] The present invention is described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 It is a structural schematic diagram of a test bench for full flow field display of an axial flow blood pump provided by the present invention.

[0035] Figure 2 yes Figure 1 Schematic diagram of the structure of the upper and lower baffles.

[0036] Figure 3It is a schematic diagram of the structure of active magnet and passive magnet.

[0037] Figure 4 Schematic diagram of an example of the initial relative angle between the active magnet and the passive magnet.

[0038] Figure 5 is a graph of the torque of the passive magnet versus the initial relative angle.

[0039] Figure 6a This is the relationship between the speed (counterclockwise) of the passive magnet and the voltage.

[0040] Figure 6b This is the relationship between the speed (clockwise) of the passive magnet and the voltage.

[0041] Figure 7a This is the relationship between the active magnet speed (counterclockwise) and voltage change.

[0042] Figure 7b This is the relationship between the speed (clockwise) of the passive magnet and the voltage change.

[0043] Figure 8a This is the relationship between the speed and voltage of the active magnet and the passive magnet in the forward and reverse rotation conditions (counterclockwise).

[0044] Figure 8b This is the relationship between the speed and voltage of the active magnet and the passive magnet in the forward and reverse rotation conditions (clockwise).

[0045] Figure 9a It is a graph showing the relationship between the speed of the passive magnet and the speed of the active magnet (counterclockwise).

[0046] Figure 9b It is the relationship between the speed of the passive magnet and the speed of the active magnet (clockwise). DETAILED DESCRIPTION

[0047] The present invention provides a test bench for displaying the flow field inside an axial flow blood pump - a test bench in which the rotor impeller of the axial flow blood pump is driven by magnetic coupling, the active magnet used for the magnetic coupling drive has no contact with the axial flow blood pump, the pump casing of the axial flow blood pump is made of transparent materials such as acrylic or quartz glass, the flow field inside the pump is not blocked by external structures, and the flow field inside the entire pump can be directly observed.

[0048] like Figure 1 The figure shows a test bench for displaying the full flow field of an axial blood pump provided by the present invention. An axial blood pump fixing device and an axial blood pump driving device are arranged on the test bench. The axial blood pump driving device is a non-contact magnetic coupling driving device, which includes an active magnet 7 and a motor 1. The motor 1 is connected to the active magnet 7. Specifically, the motor 1 is at the bottom and the active magnet 7 is at the top, and they are connected by a coupling 4 so that the active magnet 7 rotates.

[0049] The passive magnet 6 and the active magnet 7 in the axial flow blood pump are arranged side by side with parallel axes. The active magnet 7 is driven to rotate by the motor 1, thereby driving the passive magnet 6 of the rotor impeller in the axial flow blood pump for testing set on the axial flow blood pump fixing device to rotate. Matching this, the pump housing of the axial flow blood pump is made of transparent material.

[0050] The active magnet 7 drives the passive magnet 6 to rotate in the same direction. The active magnet can rotate counterclockwise or clockwise. When the active magnet rotates forward, the passive magnet rotates forward, and when the active magnet rotates reversely, the passive magnet rotates reversely.

[0051] Specifically, the structure of the test bench is:

[0052] like Figure 1 and Figure 2 As shown, the output shaft of the motor 1 is arranged vertically upward, a bottom plate 2 is arranged at the upper end of the driving motor 1, and the output shaft of the driving motor 1 is located in the middle of the bottom plate 2;

[0053] A test frame is arranged above the bottom plate 2, and the test frame comprises an upper baffle plate 8, a lower baffle plate 5 and four screw rods 3. The upper baffle plate 8, the lower baffle plate 5 and the four corners of the bottom plate 2 are provided with corresponding upper and lower through holes. The structure of the lower baffle plate 5 is the same as that of the upper baffle plate 8. For details, see the diagram showing the lower baffle plate. Figure 2 , through holes 51 are set at the four corners of the lower baffle 5. By inserting four screws 3 into the through holes at the four corners of the bottom plate 2, the lower baffle 5 and the upper baffle 8, and fitting nuts, the upper baffle 8, the lower baffle 5 and the bottom plate 2 are fixed at a set interval up and down, and corresponding mounting holes are set up on the upper baffle 8 and the lower baffle 5, such as Figure 2 As shown, one mounting hole is arranged at the center of the lower baffle plate 5 to form an active magnet mounting hole 53, and the other mounting hole is next to the active magnet mounting hole 53 to form an axial blood pump mounting hole 52. The axial distance between the two mounting holes is less than 50 mm, and the active magnet mounting hole 53 and the axial blood pump mounting hole 52 are arranged with bearing supports of the active magnet and the axial blood pump, and the active magnet 7 and the axial blood pump 6 are supported in parallel on the bearing supports of the corresponding mounting holes on the lower baffle plate and the upper baffle plate.

[0054] The set distance between the axial blood pump bearing support and the active magnet should ensure that the active magnet 7 can magnetically couple and drive the passive magnet in the axial blood pump 6 on the axial blood pump bearing support to rotate; the size of the two magnets and the performance of the motor also ensure the rotation performance of the passive magnet.

[0055] The inlet and outlet of the axial flow blood pump 6 are connected to a circulation loop (not shown in the figure).

[0056] The pump housing of the axial flow blood pump 6 is made of transparent material, such as acrylic or quartz glass.

[0057] The active magnet is a permanent magnet.

[0058] The present invention uses the above-mentioned test bench to replace the motor coil with a non-contact magnetic coupling drive device to drive the rotor impeller of the axial flow blood pump to rotate. Together with the pump housing of the axial flow blood pump, the full flow field flowing in the pump can be visualized.

[0059] like Figure 3 As shown, the active magnet 7 includes an iron core shaft 71 and a permanent magnet, the permanent magnet is provided with an axial through hole, the iron core shaft, i.e. the rotating shaft 71, passes through the axial through hole and is fixed to the permanent magnet. The passive magnet 6 has the same structure, and the iron core shaft, i.e. the rotating shaft 61, is connected to the impeller.

[0060] The active magnet 7 in the axial blood pump driving device and the passive magnet 6 in the axial blood pump are both cylindrical and radially magnetized permanent magnets. The two poles of the permanent magnets are located on two opposite sides of the cylindrical permanent magnets. One half of the cylinder is the S pole and the other half is the N pole. The generatrix in the middle of the outer side of the half cylinder is the pole line A (see Figure 3 ), the pole line A forms a pole face with the axis of the magnet, the angle between the pole face 7B of the S pole magnet of the active magnet 7 and the pole face 6B of the S pole magnet of the passive magnet is the relative angle, and the relative angle before the test is not started is the initial relative angle a (such as Figure 4 shown).

[0061] Research shows that as the initial relative angle a gradually increases, the torque obtained by the rotor, i.e. the passive magnet, becomes larger and larger. When the initial relative angle a is 90° (such as Figure 4 As shown in the figure, the torque reaches its maximum value and then begins to decrease gradually, such as Figure 5 And as shown in Table 1.

[0062] Table 1: Passive permanent magnet torque changes with the starting relative angle

[0063]

[0064]

[0065] As a transmission system, in order to ensure that it can still operate under a certain load, it must ensure that the minimum torque minus the load torque is a positive value. The power P is proportional to the torque T and the angular velocity Ω, P = T*Ω, that is, the power of the magnetic drive system will increase with the increase of the starting relative angle, and reach the maximum output power at 90°.

[0066] Therefore, the initial relative angle is 90° for the relative positions of the permanent magnet array and the rotor of the magnetic drive system arranged in a semicircle.

[0067] Therefore, it is preferred that, before testing, the active magnet 7 is adjusted so that the initial relative angle is 60° to 100°.

[0068] In addition to the initial relative angle, the voltage and power of the motor also affect the rotation of the passive magnet.

[0069] Table 2 lists the structural dimensions of the active magnet and the passive magnet in one embodiment.

[0070] Table 2 Device related parameters

[0071]

[0072]

[0073] Table 3 lists the corresponding data of the motor voltage and the rotation speed of the active magnet and the passive magnet.

[0074] Table 3 Device speed data table

[0075]

[0076] Figure 6a , Figure 6b as well as Figure 7a , Figure 7b The relationship between the speed of the passive magnet and the active magnet and the voltage of the motor is shown.

[0077] Experiments have found that the speed of the active magnet and the passive magnet increases with the increase of voltage. When the speed of the impeller of the axial blood pump needs to be adjusted, the speed of the active magnet is adjusted by adjusting the voltage of the motor, and then the speed of the axial blood pump is adjusted.

[0078] Under 24V voltage, the speed of the two wheels can reach more than 10000r / min, which is enough to meet the speed requirement of the axial flow blood pump impeller.

[0079] In addition, from Figure 8a , Figure 8b as well as Figure 9a , Figure 9b It can be seen that by using the non-contact magnetic coupling method in this test bench, the rotation speed consistency of the active magnet and the passive magnet is good, whether in the clockwise or counterclockwise case, no matter whether the two magnets rotate clockwise or counterclockwise, they follow each other very well. In each figure, they almost overlap into one line, indicating that the rotation speed of the two wheels can be kept basically consistent.

[0080] The active magnet and the passive magnet in the blood pump are both permanent magnets. After magnetization, they have permanent magnetic force and are not easy to demagnetize. In the absence of interference from an external magnetic field, the permanent magnet will have strong magnetism, and the magnetic field generated by this magnetism is also relatively stable. The magnetic field can pass through non-magnetic materials such as the pump casing to transmit magnetic force, making it very suitable as a component of the magnetic coupling drive of an axial flow blood pump. The magnetic field generated by the permanent magnet is used to achieve opposites attracting each other and likes repelling each other, and the process of converting magnetic energy into mechanical energy through magnetic coupling. The active magnet and passive magnet of the permanent magnet do not need direct contact to complete the energy transfer, which reduces friction loss and has the characteristics of very low noise.

[0081] The outstanding features of this test bench are that the rotor impeller of the axial blood pump is driven to rotate by non-contact magnetic coupling, the pump housing of the axial blood pump is made of transparent material, and the entire flow field in the pump is not blocked and can be observed.

Claims

1. A test bench for displaying the full flow field of an axial blood pump, characterized in that: An axial blood pump fixing device and an axial blood pump driving device are arranged on the test bench. The tested axial blood pump is arranged on the axial blood pump fixing device. The axial blood pump driving device is a non-contact magnetic coupling driving device, which includes an active magnet and a driving motor. The driving motor is connected to the active magnet. The active magnet and the passive magnet of the rotor impeller in the axial blood pump are placed in parallel to form a non-contact magnetic coupling driving relationship, so that the active magnet rotates, thereby driving the passive magnet of the rotor impeller in the axial blood pump arranged on the axial blood pump fixing device to rotate. Matching this, at least a part of the pump housing of the axial blood pump is made of transparent material; The structure of the test bench is: The output shaft of the driving motor is arranged vertically upward, a bottom plate is arranged at the upper end of the driving motor, and the output shaft of the driving motor passes through a through hole on the bottom plate and is located in the middle of the bottom plate; A test frame is arranged above the bottom plate, on which an active magnet is rotatably arranged, and the active magnet is connected to the output shaft of the drive motor; a bearing support is also arranged on the test frame, on which an axial blood pump for testing is arranged, so that the axial blood pump is arranged parallel to the axis of the active magnet, and a set distance is arranged between the bearing support of the axial blood pump and the active magnet, and the set distance enables the active magnet to magnetically couple and drive the passive magnet in the axial blood pump on the bearing support of the axial blood pump to rotate; The inlet and outlet of the axial flow blood pump are connected to a circulation loop; The test frame includes an upper baffle, a lower baffle and four screws. The upper baffle, the lower baffle and the four corners of the bottom plate are provided with corresponding upper and lower through holes. The four screws are inserted into the through holes at the four corners and matched with nuts so that the upper baffle, the lower baffle and the bottom plate are fixed at set intervals. The upper baffle and the lower baffle are provided with corresponding upper and lower mounting holes, and the bearing supports of the active magnet and the axial blood pump are provided in the mounting holes, so that the active magnet and the axial blood pump are arranged in parallel between the lower baffle and the upper baffle.

2. The test bench for full flow field display of an axial flow blood pump according to claim 1, characterized in that: The pump housing of the axial flow blood pump is entirely made of transparent material.

3. The test bench for full flow field display of an axial flow blood pump according to claim 1 or 2, characterized in that: The active magnet in the axial flow blood pump driving device and the passive magnet in the axial flow blood pump are both cylindrical and radially magnetized permanent magnets, and the two poles of the permanent magnet are located on two opposite sides of the cylindrical permanent magnet.

4. The test bench for full flow field display of an axial flow blood pump according to claim 1 or 2, characterized in that: The structure of the active magnet is: comprising an iron core shaft and a permanent magnet, wherein the permanent magnet is provided with an axial through hole, and the iron core shaft, i.e. the rotating shaft, passes through the axial through hole and is fixedly integrated with the permanent magnet; and / or, The motor is a DC motor; and / or, The voltage of the motor is adjustable; and / or, When the permanent magnet of the passive magnet is 20 mm long and the permanent magnet diameter is 8 mm, the permanent magnet of the active magnet is 20 mm long and the permanent magnet diameter is 10.7 mm; and / or, The axial distance between the two mounting holes of the active magnet and the passive magnet on the test bench is less than 50-60 mm.

5. The test bench for full flow field display of an axial flow blood pump according to claim 1, characterized in that: The rotating shaft of the active magnet extends downward from the lower baffle plate and is fixed to the output shaft of the driving motor extending upward through a coupling.

6. A method for testing the flow field of an axial blood pump using the test bench as claimed in any one of claims 1 to 5, comprising the following steps: Sprinkle fluorescent particles into the test fluid and start the drive motor; The laser directly irradiates the fluorescent particles in the flow field of the transparent axial blood pump from any direction. The CCD camera located perpendicular to the laser directly captures the flow field inside the transparent axial blood pump.

7. The method according to claim 6, characterized in that: The cylindrical active magnet in the axial flow blood pump driving device and the passive magnet in the axial flow blood pump have a generatrix in the middle of the outer side of half the cylinder, which is the pole line A. The pole line A forms a pole plane with the axis of the magnet. At the beginning of the test, the angle between the pole planes of the same magnetic poles of the active magnet and the passive magnet is the initial relative angle, which is 60° to 100°.

8. The method according to claim 6 or 7, characterized in that: When the rotation speed of the impeller of the axial blood pump needs to be adjusted, the rotation speed of the active magnet is adjusted by adjusting the voltage of the motor, thereby adjusting the rotation speed of the axial blood pump.

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