JP2004278375A - Axial flow pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an axial flow pump causing no coagulation of blood in a bearing part, causing no failure, and having durability in a blood pump for an artificial heart. <P>SOLUTION: A motor stator 3d is arranged in an outer peripheral part of a pipe body 3 having a spindle-shaped recessed part 3b in an inner peripheral part; a permanent magnet 4d is sealed on the swelling inside of an outside cylindrical body 4a of swelling the outer peripheral part in a spindle shape; a motor rotor 4 formed by arranging a screw type impeller 4c in a central part of the outside cylindrical body 4a is arranged by loosely fitting to the pipe body 3; and clearance 3c between an outer peripheral surface of the motor rotor 4 and an inner peripheral surface of the pipe body 3 is formed as a dynamic pressure bearing by a hydraulic fluid. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an axial flow pump, particularly to an axial flow pump useful as a pump for transporting blood of an artificial heart.
[0002]
[Prior art]
As a conventional artificial heart pump of this type, there is known a pump in which a motor installed at a position distant from a propeller of an axial pump drives the propeller through a long drive shaft (for example, for example). See Patent Document 1.).
[0003]
Although this is not an artificial heart pump, an impeller of an axial flow pump having a stator winding provided on the outer periphery of a tube body of a fluid passage and having a rotor core and an annular permanent magnet on the outer periphery is used as the fluid pump. There is an example in which a spindle in a pipe of a passage is rotatably provided (for example, see Patent Document 2).
[0004]
[Patent Document 1]
JP-A-7-178165 [Patent Document 2]
JP-A-11-37079
[Problems to be solved by the invention]
When the axial flow pump according to the prior art is used as a blood pump for an artificial heart, fragile platelets and the like in blood that have penetrated into the bearing of the pump coagulate in the bearing, and hinder the rotation of the blood pump or prevent such coagulation. However, there is a problem that the blood may be carried on blood and clog blood vessels. In addition, since blood has no lubricating property, there is a problem that the bearing portion is liable to be worn and its durability is limited.
[0006]
The present invention solves the above-mentioned problems, and provides an axial flow pump with improved durability compared to conventional pumps in which blood does not coagulate in a bearing portion of the pump and wear of the bearing portion and failure of the pump do not occur. The purpose is to do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an axial flow pump in which a motor stator is provided on an outer peripheral portion of a pipe forming a fluid flow path and a motor rotor having an impeller is provided in the pipe. A dynamic pressure bearing using the fluid was formed between an outer peripheral surface of the outer cylindrical body and an inner peripheral surface of the tubular body, provided in an outer cylindrical body having an outer periphery having a smaller diameter than the inner periphery of the tubular body.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
A first embodiment of the present invention will be described with reference to FIG.
[0009]
FIG. 1 is a vertical cross-sectional view along the center of rotation of an axial flow pump 1 of the present embodiment, and reference numeral 2 denotes a pipe through which a fluid flows.
[0010]
The axial flow pump 1 includes a pipe 3 forming a part of the pipe 2 and a motor rotor 4 rotatably supported in the pipe 3.
[0011]
The motor rotor 4 is provided with an outer cylindrical body 4a whose central portion is bulged in a mountain shape over the entire circumference to form a spindle, and a cylindrical hole 4b provided inside the outer cylindrical body 4a and concentric with the outer cylindrical body 4a. It comprises a screw type impeller 4c.
[0012]
The tubular body 3 has a spindle-shaped concave portion 3b formed by recessing the inside in a chevron shape over the entire circumference in accordance with the outer shape of the outer tubular body 4a, and an outer peripheral portion of the outer tubular body 4a and the tubular body. A gap 3c between the spindle 3 and the inner periphery of the spindle-shaped recess 3b is formed so as to be loosely fitted with at least a required minimum gap (for example, 0.1 mm). Further, a ring groove or a screw groove is provided on the outer peripheral portion of the outer cylindrical body 4a to form a dynamic pressure bearing.
[0013]
A motor stator 3d is provided on an outer peripheral portion of the tube 3, and a permanent magnet 4d is sealed in a portion of the outer cylindrical body 4a which protrudes in a mountain shape. The rotation of the motor rotor 4 is performed by the action of the permanent magnet 4d.
[0014]
Next, the operation and effect of the present embodiment will be described.
[0015]
When a current flows through the winding of the motor stator 3d and the motor rotor 4 is driven to rotate in the direction of arrow B, the fluid flows in the direction of arrow A by the action of the screw impeller 4c.
[0016]
Part of this fluid also flows into the gap 3c between the outer peripheral portion of the motor rotor 4 and the tube 3, but since the outer shape of the outer tube 4a is a spindle-shaped dynamic pressure bearing, the motor rotor 4 and the tube The motor rotor 4 floats by the dynamic pressure of the fluid entrapped between the motor rotor 3 and the fluid rotor 3 so that the gap 3c therebetween is maintained at a required gap value.
[0017]
That is, since the hydrodynamic bearings arranged obliquely function as journal bearings and thrust bearings, thrust bearings are not required, and a larger bearing gap can be realized as compared with conventional slide bearings.
[0018]
For example, even when the fluid is blood, small particles such as platelets and blood cells in the blood are not crushed into a paste, which is safe as a blood pump for an artificial heart.
[0019]
Further, since the structure is simple, it is possible to easily cope with downsizing of a device required as a blood pump.
[0020]
In the present embodiment, the shape of the spindle-shaped bulging portion of the outer cylindrical body 4a is a Mt. Fuji shape having a flat portion on the top surface, but it may be formed on the arc-shaped bulging top surface. Good.
[0021]
A second embodiment of the present invention will be described with reference to FIGS.
[0022]
FIG. 2 is a longitudinal sectional view of the axial flow pump 11 according to the present embodiment, in which reference numeral 12 denotes a pipe forming a part of a fluid conduit, and reference numeral 13 denotes a motor rotor having an impeller existing in the pipe 12. .
[0023]
The motor rotor 13 has an outer cylindrical body 13a formed in a spindle shape by bulging a central portion into a mountain shape over the entire circumference. A plurality of impellers 13b are provided inside the outer cylindrical body 13a, and a blade of the axial flow pump is provided. Is formed.
[0024]
The tubular body 12 also has a spindle-shaped concave portion 12a formed by recessing the inner peripheral portion in a chevron shape over the entire periphery in accordance with the outer cylindrical body 13a.
[0025]
FIG. 3 is a cross-sectional view of the tubular body 12 and the motor rotor 13 in a cross section perpendicular to the axis of the bulging portion 12a.
[0026]
Reference numeral 13c denotes a permanent magnet sealed in the impeller 13b.
[0027]
A motor stator 14 is provided on the outer peripheral portion of the tube 12, and the motor rotor 13 is driven to rotate by the motor stator 14 and the permanent magnet 13c sealed in the impeller 13b.
[0028]
The gap 15 between the inner peripheral surface of the concave portion 12a and the outer peripheral surface of the outer cylindrical body 13a is formed so as to be loosely fitted with at least a required minimum gap (for example, 0.1 mm). Further, a ring groove or a screw groove is provided on the outer peripheral portion of the outer cylindrical body 13a to form a dynamic pressure bearing.
[0029]
Next, the operation and effects of the present embodiment will be described.
[0030]
When a current flows through the windings of the motor stator 14 and the motor rotor 13 is driven to rotate in the direction of arrow B, fluid flows in the direction of arrow A by the action of the impeller 13b. Part of this fluid also flows into the gap 5 between the outer peripheral portion of the motor rotor 13 and the tube 12, but since the outer shape of the outer cylinder 13a is a spindle-shaped dynamic pressure bearing, the outer rotor 13a and the outer tube The motor rotor 13 floats by the dynamic pressure of the fluid entrained between the body 12 and acts so that the gap 15 between them is maintained at a required gap value.
[0031]
Thus, the present embodiment is substantially the same as in the first embodiment, but a plurality of impellers 13b in which permanent magnets 13c are sealed are used instead of the screw-type impellers 4c in the first embodiment. It differs from the first embodiment in that it is used.
[0032]
【The invention's effect】
As described above, according to the present invention, since the bearing portion is provided outside the impeller, a larger bearing area can be obtained than a conventional pump having a bearing portion inside the impeller, and the bearing portion is a spindle type. As a result, the fluid flow in the bearing portion becomes smooth, and furthermore, since the rotating body and the stationary body do not come into contact with each other by using the dynamic pressure bearing, blood coagulates in the bearing portion when used as a blood pump. This has the effect of providing a durable axial flow pump without any failure.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an axial flow pump according to a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of an axial flow pump according to a second embodiment of the present invention.
FIG. 3 is a cross-sectional view of the axial flow pump of the second embodiment in a cross section perpendicular to the axis.
[Explanation of symbols]
1, 11 axial flow pump 3, 12 pipe 3b, 12a spindle-shaped recess 3d, 14 motor stator 4, 13 motor rotor 4a, 13a outer cylinder 4c screw (impeller)
13b impeller

Claims (3)

In an axial flow pump provided with a motor stator at an outer peripheral portion of a tube forming a fluid flow path and also provided with a motor rotor having an impeller in the tube, the motor rotor is provided with an outer periphery having a smaller diameter than the inner periphery of the tube. An axial flow pump, wherein the hydrodynamic bearing is provided between the outer peripheral surface of the outer cylindrical body and the inner peripheral surface of the tubular body. Along the entire circumference of the outer cylindrical body, a central portion is bulged in a chevron shape to form a spindle shape. The shaft according to claim 1, wherein a portion between the bulged outer peripheral surface of the outer cylindrical body and the inner peripheral surface of the concave portion of the tubular body is formed in a dynamic pressure bearing using the fluid. Flow pump. The axial flow pump according to claim 1, wherein the impeller comprises a screw provided in a flow path in the outer cylinder.

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