Liquid dynamic bearing and rotary blood pump

Abstract

The present invention relates to a liquid hydrodynamic bearing and a rotary blood pump, comprising a first shell, a thrust plate and a second shell, wherein the shaft end of the first shell facing the thrust plate is the first shell end, the shaft end of the thrust plate facing the first shell end is the first thrust end, the shaft end of the second shell facing the thrust plate is the second shell end, the shaft end of the thrust plate facing the second shell end is the second thrust end, one of the first shell end and the first thrust end is provided with a first spiral groove, and one of the second shell end and the second thrust end is provided with a second spiral groove; the first spiral groove is asymmetrical to the second spiral groove, the thrust plate can stably suspend at different axial positions under different speed conditions, can squeeze out the liquid in the liquid hydrodynamic bearing by changing the speed of the thrust plate, and avoid part of the liquid from being retained in the liquid hydrodynamic bearing for a long time, and when applied to a rotary blood pump, can improve the blood compatibility at the gap of the liquid hydrodynamic bearing and prevent thrombosis.

Description

Technical Field

[0001] The invention belongs to the field of bearings, and in particular relates to a liquid dynamic pressure bearing and a rotary blood pump. Background Art

[0002] Fluid dynamic lubrication relies on the relative motion between a pair of lubricated solid friction surfaces to generate pressure in the lubricating fluid film between the solids to withstand external loads and avoid contact between the solids, thereby reducing friction and protecting the solid surface. The elements of fluid dynamic lubrication are: there is a wedge-shaped gap between the two solid surfaces; the gap is filled with fluid with appropriate viscosity; this fluid can be adsorbed on the two solid surfaces; the relative motion of the two solid surfaces drives the fluid to move from a large gap to a small gap.

[0003] Hydrodynamic bearings are a type of liquid bearing that uses the principle of fluid dynamic lubrication. They can be divided into radial bearings and thrust bearings according to the direction of support. Hydrodynamic bearings usually have a wedge-shaped lubricating film. In addition, there are also step-shaped and spiral-groove-shaped lubricating films, both of which can be considered a special type of wedge-shaped gap.

[0004] A shallow spiral groove is opened on the solid friction surface of the liquid dynamic pressure bearing. The groove is usually made into a rectangular cross-section. When working, the relative movement of the solid surface drives the lubricating fluid to flow along the spiral grooves. Since the gap between the friction surfaces at the ungrooved part is smaller, the lubricating fluid is blocked at the end of the groove, thereby establishing a pressure distribution to bear the load. This load-bearing principle can be applied to both thrust bearings and radial bearings.

[0005] The hydrodynamic bearing with spiral grooves has a simple structure and a small size. In addition to being suitable for high-speed rotary motion, it is also suitable for ultra-clean occasions such as rotary blood pumps. However, the two solid surfaces of the existing hydrodynamic bearings have symmetrical spiral grooves, which makes the thrust plate of the hydrodynamic bearing always hover in the middle position, which easily causes part of the liquid to be retained in the hydrodynamic bearing, affecting the delivery of the liquid. When used in rotary blood pumps, there is a risk of thrombosis. Summary of the invention

[0006] The technical problem to be solved by the present invention is: to provide a liquid dynamic pressure bearing and a rotary blood pump in view of the problem that the thrust plate of the existing solution always hovers in the middle position, which easily causes part of the liquid to be retained in the liquid dynamic pressure bearing.

[0007] In order to solve the above technical problems, an embodiment of the present invention provides a liquid dynamic pressure bearing, comprising a first housing, a thrust plate and a second housing, wherein the first housing is fixedly connected to the second housing, the thrust plate is arranged between the first housing and the second housing, and can rotate relative to the first housing and the second housing;

[0008] The shaft end of the first housing facing the thrust plate is a first housing end, the shaft end of the thrust plate facing the first housing end is a first thrust end, the shaft end of the second housing facing the thrust plate is a second housing end, the shaft end of the thrust plate facing the second housing end is a second thrust end, one of the first housing end and the first thrust end is provided with a first spiral groove, and one of the second housing end and the second thrust end is provided with a second spiral groove;

[0009] The first spiral groove is asymmetric to the second spiral groove, so that when the rotation speed of the thrust plate changes, the axial position of the thrust plate suspension changes accordingly.

[0010] Optionally, one of the first spiral groove and the second spiral groove is a spiral groove of equal depth, and the other is a spiral groove of variable depth, and the groove depth gradually decreases or increases from the outside to the inside.

[0011] Optionally, the groove depth of the first spiral groove is 0.005-0.5 mm, and the groove depth of the second spiral groove is 0.005-0.5 mm.

[0012] Optionally, one of the first spiral groove and the second spiral groove is a spiral groove with equal groove width, and the other is a spiral groove with variable groove width, and the groove width gradually decreases or increases from the outside to the inside.

[0013] Optionally, the groove width of the first spiral groove is 0.2-5 mm, and the groove width of the second spiral groove is 0.2-5 mm.

[0014] Optionally, the number of the first spiral grooves is set to 4 to 36, and the number of the second spiral grooves is set to 4 to 36.

[0015] Optionally, the groove length ratio of the first spiral groove is 0-1, and the spiral angle ranges from 0 to 85°; the groove length ratio of the second spiral groove is 0-1, and the spiral angle ranges from 0 to 85°.

[0016] Optionally, a gap between the first thrust end and the first shell end is 0.005-0.5 mm, and a gap between the second thrust end and the second shell end is 0.005-0.5 mm.

[0017] Optionally, the shape of any one of the first spiral grooves is a double circular arc shape, a logarithmic spiral shape, an oblique straight line shape or a parabola shape, and the shape of any one of the second spiral grooves is a double circular arc shape, a logarithmic spiral shape, an oblique straight line shape or a parabola shape.

[0018] An embodiment of the present invention further provides a rotary blood pump, comprising the aforementioned liquid dynamic pressure bearing.

[0019] The liquid hydrodynamic bearing and the rotary blood pump provided by the embodiments of the present invention have a first shell and a second shell that provide a certain axial net bearing capacity for the thrust plate, and the first spiral groove and the second spiral groove of the liquid hydrodynamic bearing are set to be asymmetrical. When the rotation speed of the thrust plate changes, the thrust plates are subjected to thrusts of different magnitudes on both axial sides, and the thrust plate moves axially along the liquid hydrodynamic bearing, thereby changing the axial gap between the thrust plate and the first shell or the second shell, and finally stabilizing at a force balance under a corresponding rotation speed. Thus, the thrust plate can be stably suspended in different axial positions under different rotation speed conditions through the setting of the asymmetric first spiral groove and the second spiral groove, and the liquid in the liquid hydrodynamic bearing can be squeezed out by changing the rotation speed of the thrust plate, thereby preventing part of the liquid from being retained in the liquid hydrodynamic bearing for a long time. When applied to a rotary blood pump, the blood compatibility at the gap of the liquid hydrodynamic bearing can be improved to prevent thrombosis. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic diagram of the structure of a liquid dynamic bearing provided by an embodiment of the present invention;

[0021] Figure 2 for Figure 1 The enlarged image of the middle A after rotation;

[0022] Figure 3 for Figure 1 The enlarged view of the middle B after rotation;

[0023] The reference numerals in the specification are as follows:

[0024] 1. first shell; 11. first shell end; 12. first spiral groove;

[0025] 2. thrust plate; 21. first thrust end; 22. second thrust end;

[0026] 3. Second shell body; 31. Second shell end; 32. Second spiral groove. DETAILED DESCRIPTION

[0027] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0028] like Figures 1 to 3 As shown, the liquid dynamic bearing provided by the embodiment of the present invention comprises a first housing 1, a thrust plate 2 and a second housing 3, wherein the first housing 1 is fixedly connected to the second housing 3, and the thrust plate 2 is arranged between the first housing 1 and the second housing 3 and can rotate relative to the first housing 1 and the second housing 3;

[0029] The shaft end of the first housing 1 facing the thrust plate 2 is the first housing end 11, the shaft end of the thrust plate 2 facing the first housing end 11 is the first thrust end 21, the shaft end of the second housing 3 facing the thrust plate 2 is the second housing end 31, the shaft end of the thrust plate 2 facing the second housing end 31 is the second thrust end 22; one of the first housing end 11 and the first thrust end 21 is provided with a first spiral groove 12, Figure 1 The first spiral groove 12 is provided on the first shell end 11, and the first thrust end 21 is provided as a smooth axial plane; the second spiral groove 32 is provided on one of the second shell end 31 and the second thrust end 22. Figure 1 The second spiral groove 32 is provided at the second shell end 31, and the second thrust end 22 is provided as a smooth axial plane; in this application, for the convenience of description, the first spiral groove 12 and the second spiral groove 32 are collectively referred to as spiral grooves;

[0030] The first spiral groove 12 is asymmetric to the second spiral groove 32 (the groove structure composed of all the first spiral grooves 12 is asymmetric to the groove structure composed of all the second spiral grooves 32), so that the suspended axial position of the thrust plate 2 changes accordingly when the rotation speed of the thrust plate 2 changes.

[0031] When in use, the thrust plate 2 rotates clockwise relative to one of the first shell 1 and the second shell 3, and rotates counterclockwise relative to the other, thereby relying on the relative movement of the solid surface to drive the liquid to flow along the first spiral groove 12 and the second spiral groove 32. Specifically, the scheme in which the liquid flows from the periphery to the center of the liquid hydrodynamic bearing is a pump-in bearing, or the scheme in which the liquid flows from the center to the periphery of the liquid hydrodynamic bearing is a pump-out bearing. The rotation direction of the thrust plate can be determined according to actual needs, and the rotation direction of the spiral groove can be changed accordingly. Since the ends of the first spiral groove 12 and the second spiral groove 32 are not conductive, the gap between the friction surfaces (i.e., between the first thrust end 21 and the first shell end 11, and between the second thrust end 22 and the second shell end 31) is smaller at the non-grooved part, and the liquid is blocked at the end of the spiral groove, thereby establishing a pressure distribution to bear the load. In addition, when the thrust plate 2 rotates to drive the liquid to flow from the grooved part to the non-grooved part, a pressure distribution can also be established to bear the load.

[0032] The liquid hydrodynamic bearing provided in the embodiment of the present invention has a first shell 1 and a second shell 3 that provide a certain axial net bearing capacity for the thrust plate 2, and the first spiral groove 12 and the second spiral groove 32 of the liquid hydrodynamic bearing are set to be asymmetrical. When the rotation speed of the thrust plate 2 changes, the thrust plates 2 are subjected to thrusts of different magnitudes on both axial sides, and the thrust plate 2 moves along the axial direction of the liquid hydrodynamic bearing, thereby changing the axial clearance between the thrust plate 2 and the first shell 1 or the second shell 3, and finally stabilizing at a force balance under the corresponding rotation speed. Thus, the thrust plate 2 can be stably suspended in different axial positions under different rotation speed conditions through the setting of the asymmetric first spiral groove 12 and the second spiral groove 32, and the liquid in the liquid hydrodynamic bearing can be squeezed out by changing the rotation speed of the thrust plate 2, thereby preventing part of the liquid from being retained in the liquid hydrodynamic bearing for a long time. When applied to a rotary blood pump, the blood compatibility at the clearance of the liquid hydrodynamic bearing can be improved to prevent thrombosis.

[0033] In one embodiment, one of the first spiral groove 12 and the second spiral groove 32 is a spiral groove of equal groove depth ( Figure 2 The first spiral groove 12 shown is a spiral groove of equal groove depth), and the other is a spiral groove of variable groove depth ( Figure 3 The second spiral groove 32 shown is a variable groove depth spiral groove), and the groove depth gradually decreases or increases from the outside to the inside, and the structure is simple. In addition to the liquid being blocked at the end of the spiral groove to establish the pressure distribution, the pressure distribution is also established by forming a wedge-shaped gap between the first housing 1 or the second housing 3 and the thrust plate 2 at the variable groove depth spiral groove. The fluid is transported between the wedge-shaped gaps at the spiral groove of the liquid dynamic pressure bearing through relative rotation, so that the load-bearing capacity of the liquid dynamic pressure bearing is greatly improved;

[0034] The first spiral groove 12 and the second spiral groove 32 can be arranged in opposite positions, and other parameters (such as groove width, groove length ratio, groove shape, spiral angle, and number of grooves) are the same, and only one spiral groove is arranged as a variable groove depth spiral groove, so that the groove depth of one spiral groove is finely adjusted on the basis of the existing liquid dynamic pressure bearing, and the asymmetric arrangement of the first spiral groove 12 and the second spiral groove 32 is realized, which further simplifies the structure and reduces the cost of improvement. Of course, the groove depths of the first spiral groove 12 and the second spiral groove 32 from the outside to the inside can also remain unchanged, or both change.

[0035] In one embodiment, if Figure 2 and Figure 3 As shown, the groove depth 1a of the first spiral groove 12 is 0.005-0.5mm, and the groove depth 3a of the second spiral groove 32 is 0.005-0.5mm, so that when the thrust plate 2 rotates, the first shell 1 and the second shell 3 can provide appropriate thrust to the thrust plate 2 through the liquid, avoiding the opening of the spiral groove affecting the service life of the corresponding structure on the liquid hydrodynamic bearing (the first shell 1, the thrust plate 2 or the second shell 3).

[0036] In one embodiment, one of the first spiral groove 12 and the second spiral groove 32 is a spiral groove of equal groove width, and the other is a spiral groove of variable groove width, and the groove width gradually decreases or increases from the outside to the inside, and the structure is simple; the first spiral groove 12 and the second spiral groove 32 can be set relative to each other, and other parameters (such as groove depth, groove length ratio, groove shape, spiral angle, number of grooves) are the same, and only one spiral groove is set as a spiral groove of variable groove width, so that the groove width of one spiral groove is fine-tuned on the basis of the existing liquid dynamic pressure bearing, and the asymmetric setting of the first spiral groove 12 and the second spiral groove 32 is realized, which further simplifies the structure and reduces the cost of improvement. Of course, the groove widths of the first spiral groove 12 and the second spiral groove 32 from the outside to the inside can also remain unchanged, or both change.

[0037] In one embodiment, if Figure 1 As shown, the groove width 1b of the first spiral groove 12 is 0.2 to 5 mm, and the groove width 3b of the second spiral groove 32 is 0.2 to 5 mm, so that when the thrust plate 2 rotates, the first shell 1 and the second shell 3 can provide appropriate thrust to the thrust plate 2 through the liquid, avoiding the opening of the spiral groove affecting the service life of the corresponding structure on the liquid hydrodynamic bearing (the first shell 1, the thrust plate 2 or the second shell 3).

[0038] In one embodiment, the number of the first spiral grooves 12 is set to 4 to 36, and the number of the second spiral grooves 32 is set to 4 to 36, so that when the thrust plate 2 rotates, the first shell 1 and the second shell 3 can provide appropriate thrust to the thrust plate 2 through the liquid. The other parameters (such as groove width, groove depth, groove length ratio, groove shape, spiral angle) of the first spiral groove 12 and the second spiral groove 32 can be set to be the same, and only the number of the two spiral grooves is different, so as to fine-tune the number of spiral grooves on the basis of the existing liquid dynamic pressure bearing, and realize the asymmetric setting of the first spiral groove 12 and the second spiral groove 32.

[0039] In one embodiment, the groove length ratio of the first spiral groove 12 is 0-1, and the groove length ratio of the second spiral groove 32 is 0-1, which is selected according to actual needs so that when the thrust plate 2 rotates, the first shell 1 and the second shell 3 can provide appropriate thrust to the thrust plate 2 through the liquid. The groove length ratio of the first spiral groove 12 and the groove length ratio of the second spiral groove 32 can be equal or unequal.

[0040] Preferably, if Figure 1As shown, the end faces of the first shell end 11, the first thrust end 21, the second thrust end 22 and the second shell end 31 are circular faces, the outer end of the first spiral groove 12 is located on the first outer circle, the inner ends of all the first spiral grooves 12 are located on the first inner circle, the first outer circle, the second inner circle and the center point of the circular surface of the structure where the first spiral groove 12 is located coincide with each other, the radius of the first outer circle is 1e, the radius of the first inner circle is 1d, the inner diameter of the first shell end 11 is 1r, and the groove length ratio of the first spiral groove 12 = (1e-1d) / 1r; the outer end of the second spiral groove 32 is located on the second outer circle, the inner ends of all the second spiral grooves 32 are located on the second inner circle, the second outer circle, the second inner circle and the center point of the circular surface of the structure where the second spiral groove 32 is located coincide with each other, the radius of the second outer circle is 3e, the radius of the second inner circle is 3d, the inner diameter of the second shell end 31 is 3r, and the groove length ratio of the second spiral groove 32 = (3e-3d) / 3r.

[0041] In one embodiment, if Figure 1 As shown, the helical angle 1c of the first spiral groove 12 ranges from 0 to 85°; the helical angle 3c of the second spiral groove 32 ranges from 0 to 85°, which is selected according to actual needs so that when the thrust plate 2 rotates, the first shell 1 and the second shell 3 can provide appropriate thrust to the thrust plate 2 through the liquid. The helical angle of the first spiral groove 12 and the helical angle of the second spiral groove 32 can be equal or unequal. The helical angle 1c of the first spiral groove 12 is the angle between the extension direction of the outer end of the inner curved side of the first spiral groove 12 and the radial line of the first shell end 11 passing through the outer end of the inner curved side of the first spiral groove 12.

[0042] In one embodiment, if Figure 2 and Figure 3 As shown, the gap 1f between the first thrust end 21 and the first shell end 11 is 0.005-0.5 mm, and the gap 3f between the second thrust end 22 and the second shell end 31 is 0.005-0.5 mm, so that when the thrust plate 2 rotates, the first shell 1 and the second shell 3 can provide appropriate thrust to the thrust plate 2 through the liquid.

[0043] In one embodiment, the shape of any first spiral groove 12 is a double arc line, a logarithmic spiral, an oblique straight line or a parabola, and the shape of any second spiral groove 32 is a double arc line, a logarithmic spiral, an oblique straight line or a parabola. These groove shapes can allow the first shell 1 and the second shell 3 to indirectly provide axial thrust to the thrust plate 2 through the flow of liquid along the spiral groove when the thrust plate 2 rotates. Other parameters (such as groove width, groove depth, and groove length ratio) of the first spiral groove 12 and the second spiral groove 32 can be set to be the same, and the groove shape of some spiral grooves in at least one spiral groove is different from that of another spiral groove, so that the groove shape of some spiral grooves is fine-tuned on the basis of the existing liquid hydrodynamic bearing, and the asymmetric setting of the first spiral groove 12 and the second spiral groove 32 is achieved.

[0044] Specifically, multiple parameters (such as groove width, groove depth, groove length ratio, groove shape, and spiral angle) of the first spiral groove 12 and the second spiral groove 32 may be set to be different to increase the dynamic pressure.

[0045] An embodiment of the present invention further provides a rotary blood pump, comprising the liquid dynamic pressure bearing described in any of the aforementioned embodiments.

[0046] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A liquid dynamic bearing, comprising a first housing, a thrust plate and a second housing, wherein the first housing is fixedly connected to the second housing, the thrust plate is arranged between the first housing and the second housing and can rotate relative to the first housing and the second housing; The shaft end of the first housing facing the thrust plate is a first housing end, the shaft end of the thrust plate facing the first housing end is a first thrust end, the shaft end of the second housing facing the thrust plate is a second housing end, the shaft end of the thrust plate facing the second housing end is a second thrust end, one of the first housing end and the first thrust end is provided with a first spiral groove, and one of the second housing end and the second thrust end is provided with a second spiral groove; It is characterized in that The first spiral groove is asymmetric to the second spiral groove, so that when the rotation speed of the thrust plate changes, the axial position of the thrust plate suspension changes accordingly.

2. The liquid dynamic bearing according to claim 1, characterized in that: One of the first spiral groove and the second spiral groove is a spiral groove with a constant groove depth, and the other is a spiral groove with a variable groove depth, and the groove depth gradually decreases or increases from the outside to the inside.

3. The liquid dynamic bearing according to claim 1, characterized in that: The groove depth of the first spiral groove is 0.005-0.5 mm, and the groove depth of the second spiral groove is 0.005-0.5 mm.

4. The liquid dynamic bearing according to claim 1, characterized in that: One of the first spiral groove and the second spiral groove is a spiral groove with a constant groove width, and the other is a spiral groove with a variable groove width, and the groove width gradually decreases or increases from the outside to the inside.

5. The liquid dynamic bearing according to claim 1, characterized in that: The groove width of the first spiral groove is 0.2-5 mm, and the groove width of the second spiral groove is 0.2-5 mm.

6. The liquid dynamic bearing according to claim 1, characterized in that: The number of the first spiral grooves is set to be 4 to 36, and the number of the second spiral grooves is set to be 4 to 36.

7. The liquid dynamic bearing according to claim 1, characterized in that: The groove length ratio of the first spiral groove is 0-1, and the spiral angle ranges from 0 to 85°; the groove length ratio of the second spiral groove is 0-1, and the spiral angle ranges from 0 to 85°.

8. The liquid dynamic bearing according to claim 1, characterized in that: The gap between the first thrust end and the first shell end is 0.005-0.5 mm, and the gap between the second thrust end and the second shell end is 0.005-0.5 mm.

9. The liquid dynamic bearing according to claim 1, characterized in that: The shape of any of the first spiral grooves is a double arc line, a logarithmic spiral, an oblique straight line or a parabola, and the shape of any of the second spiral grooves is a double arc line, a logarithmic spiral, an oblique straight line or a parabola.

10. A rotary blood pump, characterized in that: A liquid dynamic bearing comprising the liquid dynamic bearing according to any one of claims 1 to 9.

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