Rotary kinetic fluid motors or pumps – Runner has planetary motion or rotates around oblique or...
Patent
1986-09-05
1988-02-02
Garrett, Robert E.
Rotary kinetic fluid motors or pumps
Runner has planetary motion or rotates around oblique or...
415208, F04D 3300
Patent
active
047226609
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a centrifugal pump, and more particularly to a pump which pumps out fluid rotated by a nutating impeller.
2. Description of the Related Art
A centrifugal pump which pumps out fluid rotated by a nutating impeller is disclosed in English Pat. No. 720637 and, German Patent Application Publication No. 3133177.
This pump is developed mainly for pumping fluid which must not be contaminated e.g. blood, and is characterized by having a nutating impeller.
The nutation of the impeller is an excellent suggestion in freeing fluid from inevitable contact with a bearing of a rotative impeller of a conventional pump.
But the pump has the defect of low pump efficiency, caused by fluid being forced to rotate without any restriction in the conical room enclosed by the casing of the pump.
On the other hand, another pump with a nutating impeller is disclosed in French Pat. No. 71.40652, but the pump has a defect not only of low pump efficiency caused by its inlet not being located at the center of the room in which the impeller is accommodated but also of the danger of inverse flow or flow disturbance in the room when the pressure at the outlet becomes large.
Especially during pumping of blood, the inverse flow or the flow disturbance in the pump room is unsatisfactory with regard to safety of and damaging of fluid components e.g. blood corpuscles.
SUMMARY OF THE INVENTION
The improvement of the pump efficiency and the prevention of inverse flow or flow disturbance in the pump room are very important when putting the pump of this type to practical use and the present invention proposes the improvement thereof.
That is, it is an object of the present invention to provide a centrifugal pump with a nutating impeller having a high pump efficiency.
It is another object of the present invention to provide a centrifugal pump which effectively prevents fluid components, e.g., blood corpuscles from being damaged which is caused by inverse flow or flow disturbance in the pump room.
To attain the stated objects, the present invention provides a centrifugal pump with a nutating impeller which is characterized by being provided with a flow guide wall defining an annular space in a casing by projecting into the casing from the center of the circular end face of the casing, the flow guide wall also defining an inner face of the annular space and being provided with an inlet open at the center of the circular end face of the casing.
The pump efficiency of the centrifugal pump of the present invention is greater than one not having a flow guide wall as shown by results from experiments. (In FIG. 7 f represents the pump of the present invention and g represents a pump that does not have a flow guide wall.)
A lesser flow disturbance in the pump room of the present invention is observed in experiments.
BRIEF DESCRIPTION OF THE DRAWINGS
The stated object and other characteristics of the present invention will be better understood by referring to the description of the embodiments of the present invention taken in conjunction with the accompanying drawings in which:
FIG. 1 is a side sectional view of a centrifugal pump according to the present invention;
FIG. 2 is a transverse sectional view taken along the line II--II of FIG. 1;
FIG. 3 is a perspective view of the impeller of FIG.1;
FIG. 4 is a side sectional view of another modification of a centrifugal pump according to the present invention;
FIG. 5 is a side sectional view of another modification of a centrifugal pump according to the present invention;
FIG. 6 is a side sectional view of another modification of a centrifugal pump according to the present invention;
FIG. 7 is a graph showing the characteristic of flow rate to pump efficiency of a centrifugal pump according to the present invention compared with that of a conventional one.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 1 and FIG. 2 show an embodiment of the centrifugal pump of the present invention, the centrifugal pump (1) h
REFERENCES:
patent: 2353373 (1944-07-01), Thompson
patent: 2773453 (1956-12-01), Gemeinhardt
patent: 3132493 (1964-05-01), Peckham et al.
Garrett Robert E.
Pitko Joseph M.
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