Impeller of liquid pump

Details Impeller of liquid pump Impeller of liquid pump

2002-05-01

2003-10-28

Nguyen, Ninh H. (Department: 3745)

Rotary kinetic fluid motors or pumps

With means for re-entry of working fluid to blade set

Turbine regenerative pump

C416S22300B, C416S237000

Reexamination Certificate

active

06638009

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of Invention
The invention relates to the technical field of an impeller for a liquid pump provided in the fuel tank of vehicle and pumping a liquid.
2. Description of Related Art
This type of liquid pump is, for example, a fuel pump arranged in a fuel tank. In general, a fuel pump having the following structure is well known. More specifically, an impeller is rotatably mounted in a pump chamber, which is formed with an intake port and an outlet port at its outer-radial portion, and fuel flowing from the intake port is pumped from the outlet port based on a rotation of the impeller. The impeller of the fuel pump has a structure as shown in FIGS.
8
(A)-
8
(C), for example. That is, a disk plate member (impeller)
14
having a predetermined plate thickness is formed with a plurality of vanes
14
a
, which extend substantially radially or approximately perpendicular to a tangent to the circumferential direction, and a plurality of vane grooves
14
b
are interposed between adjacent vanes
14
a
, at the outer periphery. The vanes
14
a
and vane grooves
14
b
are formed on both plate surfaces (both sides) so that they can be alternately positioned on opposite sides of the intermediate portion M of the disk plate member
14
. In the impeller, the vane groove
14
b
has an inclined surface
14
c
, which is formed so that the inner-radial edge portion reaches the plate surface of the disk plate member
14
. With the rotation of the impeller
14
, fuel flowing from the intake port flows from the inner-radial side of the inclined surface
14
c
to the outer-diameter side thereof along the inclined surface
14
c
. Then, the fuel is rotated while forming a vortex flow between the inclined surface and a ring recess groove for a passage formed in the impeller casing that constitutes a pump chamber, and is pumped from the outlet port formed at the outer-radial side (see the outlined arrow shown in FIG.
8
(A)). In the impeller, the fuel flow is analyzed based on CFD (Computational Fluid Dynamics); as a result, the following problems (see FIGS.
8
(B) and
8
(C)) are found. First, there exists a flow colliding with a rotating direction (see arrow FIG.
8
(A)) trailing surface
14
d
which generates, an impact loss. Second, another vortex flow, different from the previously described vortex flow, is formed backward from a rotating direction leading surface
14
e
such that cavitation results. Third, stagnation is generated in the thickness direction intermediate portion of the outer-radial portion of the impeller
14
which generates a counter flow. The problems are a factor in reducing the pump's efficiency. The mentioned phenomena are believed to occur from the following cause. That is, the vortex flow flows later than a rotational speed of the vane
14
a
; on the contrary, the shape of the vane
14
a
(vane surface) of the impeller
14
is parallel to the thickness direction (rotary shaft direction) surface. Further, the outer-diameter edge portion of the vane
14
a
and the inner-radial surface of the impeller casing closely face each other.
In order to solve the problem, the impeller disclosed in Japanese Patent Application Publication (laid-open) No. 9-511812 has been proposed. As shown in FIG.
9
(A), vanes
15
a
of an impeller
15
are formed between a plurality of through holes
15
b
formed along a circumferential direction of a disk plate member. A radially inner surface
15
c
of the through hole
15
b
is formed into a surface inclined with respect to the intermediate portion M (inner-diameter edge portion reaches plate surface) so that each plate surface is further inwardly inclined, and the inclined surface is used as a fuel passage. On the other hand, the plurality of vanes
15
a
are formed with a ring portion
15
d
at the outer radial side. Further, in the impeller
15
, each vane
15
a
is formed in a state of being inclined to the rotary shaft of the disk plate member, that is, to the intermediate portion M of the disk plate member so that both plate surface sides of the disk plate member are positioned to a rotating direction leading side. The shape of the vortex flow is similar to that of the vane
15
a
(through hole
15
b
) so as to reduce a collision (impact loss) of the flow against a rotating direction trailing surface
15
e
of the through hole
15
b.
In the impeller
15
, the fuel flow is analyzed based on the CFD in the same manner as the conventional example; as a result, as shown in FIGS.
9
(B) and
9
(C), the following points are found. First, a counter flow by stagnation is reduced in the outer-diameter portion of the impeller
15
. Second, the collision of fuel with the vane
15
a
, that is, the collision with rotating direction leading and trailing surfaces
15
f
,
15
e
of the through hole
15
b
is reduced. Third, a main vortex flow is smoothly formed in a state of running along the radial inner surface
15
c
of the through hole
15
b
. Therefore, the pump's efficiency is considered as improved. However, as seen from FIG.
9
(B), in the fuel flow, a small vortex flow, which is different from the main vortex flow guided to the radially inner surface
15
c
and flowing to the outer-radial side, is formed backward of the rotating direction leading surface
15
f
of the vane groove
15
b
. Further, there exist flows which collide with the rotating direction leading and trailing surfaces
15
f
,
15
e
. As a result, like the conventional example, the cavitation and impact loss is generated as ever; therefore, these are factors in reducing the pump's efficiency.
On the other hand, in recent years, it is greatly desired to achieve a high output of a fuel pump, and to simultaneously make the fuel pump compact. In order to achieve the purpose, there is a need to further improve the pump's efficiency, and this is a problem to be solved by the invention.
SUMMARY OF THE INVENTION
The invention has been made in view of the circumstances, and therefore, an object of the invention is to solve the problems found in the prior art.
In order to achieve the object, the invention provides an impeller for liquid pump, the impeller provided in a pump chamber formed with an intake port and an outlet port, which is rotated so that a liquid taken from the intake port can be pumped from the outlet port, comprising:
a plurality of through holes penetrating the thickness of a disk plate member and formed at an outer periphery of the disk plate member along the circumferential direction thereof; and
a plurality of vanes formed between adjacent through holes,
a radial inner surface of each though hole being inclined from a thickness direction intermediate portion to an inner-radial side in order to guide a liquid to the thickness direction intermediate portion side,
the radial inner surface being inclined so that its rotating direction leading side is positioned to the inner-radial side in order to secure an area for guiding the liquid wider.
By doing so, the inflow portion of liquid, that is, the radial inner surface of the through hole has a wider area, and the flow rate of the main vortex flow increases. Therefore, pump efficiency can be improved.
Further, the invention provides the impeller for a liquid pump, wherein a radial outer surface of each though hole is inclined so that its rotating direction leading side is positioned to the inner-radial side.
Further, the invention provides the impeller for a liquid pump, wherein the radial outer surface of each though hole is inclined from the thickness direction intermediate portion to an outer-radial side of the through hole.
Further, the invention provides the impeller for a liquid pump, wherein the pump chamber is formed with a ring recess groove for a fluid passage, which faces a vane forming portion, and an inner-radial edge portion of the ring recess groove faces the rotating direction leading surface of the through hole; on the other hand, an outer-radial edge portion of the ring recess groove faces the rotating direction trailing surface thereof.
Further, the inv

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