Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Turbine regenerative pump
Reexamination Certificate
2000-10-27
2002-09-03
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Turbine regenerative pump
C415S200000
Reexamination Certificate
active
06443692
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an impeller of a circumferential current pump (so-called “wesco pump”) used as an in-tank type fuel pump of an automobile and a method of forming the impeller.
2. Description of the Prior Art
An in-tank type circumferential current pump having an improved property for being mounted to a vehicle and having a low noise and a small pressure change has been conventionally used in a fuel pump for an electronically controlled type fuel injection apparatus of an automobile.
FIGS. 23
to
25
show a circumferential current pump
51
for an automobile. The circumferential current pump
51
shown in these drawings is placed within a fuel tank (not shown), and is structured such as to apply an energy to a fuel by a vane
54
formed on an outer periphery of an impeller
52
when the impeller
52
is rotated by a motor
53
so as to increase a pressure of the fuel flowing into a pump flow passage
56
from a fuel inlet port
55
and discharge the fuel having the increased pressure to an engine side from a fuel discharge port
57
.
In the circumferential current pump
51
mentioned above, in order to maintain a pump efficiency and a discharge pressure in a desired state, it is necessary to set gaps w
1
and w
2
in a side of side surfaces
58
a
and
58
b
of the impeller
52
within a predetermined size so as to reduce a leaked flow amount. Further, in the circumferential current pump
51
mentioned above, since the impeller
52
is always in contact with the fuel within the fuel tank, a phenol resin or a PPS resin excellent in a solvent resistance is used as a material for the impeller
52
, whereby the impeller
52
is formed in a desired shape in accordance with an injection molding.
However, when using the injection molded impeller
52
as it is, the sizes of the gaps w
1
and w
2
on the side surfaces
58
a
and
58
b
of the impeller
52
do not satisfy a desirable accuracy due to a surface accuracy of the side surfaces
58
a
and
58
b
of the impeller
52
, so that desired pump efficiency and discharge pressure can not be obtained.
Accordingly, in the conventional circumferential current pump
51
, a width of the impeller
52
is finished at a high accuracy by polishing both of the side surfaces
58
a
and
58
b
of the injection molded synthetic resin impeller
52
and a surface accuracy of both of the side surfaces
58
a
and
58
b
of the impeller
52
is finished at a high accuracy. Therefore, the conventional impeller
52
has a disadvantage that a process and labor for working is much and a producing cost is increased (a first prior art).
Further, as shown in
FIG. 26
, there has been proposed an impeller
52
structured such as to reduce a resistance applied to both of the side surfaces
58
a
and
58
b
in comparison with the first prior art in which a whole of both of the side surfaces
58
a
and
58
b
forms a seal portion, by forming an annular recess
60
in both of the side surfaces
58
a
and
58
b
, forming a first seal portion S
1
in an outer peripheral side thereof and forming a second seal portion S
2
in an inner peripheral side thereof (refer to Japanese Unexamined Patent Publication No. 7-151091). However, since the impeller
52
is structured such that two seal portions S
1
and S
2
are formed in such a manner as to be apart from each other in a radial direction, it is necessary to polish both of the side surfaces
58
a
and
58
b
after the injection molding, in the same manner as that of the prior art mentioned above. Accordingly, the impeller
52
shown in
FIG. 26
also has a disadvantage that a process and labor is much and a producing cost is increased in the same manner as that of the prior art mentioned above (a second prior art).
Accordingly, the applicant of the present invention proposed an invention structured such that a recess portion
61
is formed in a center portion of both of the side surfaces
58
a
and
58
b
of the impeller
52
, a gate
62
for injection is arranged in the recess portion
61
and a pressure adjusting hole
63
is formed as shown in
FIG. 27
, whereby the injection molded impeller
52
can be used as it is without being polished (Japanese Unexamined Patent Publication No. 9-158885 (a third prior art)). However, in correspondence to a high performance of a fuel pump in recent years, it has been desired to provide an impeller having a higher accuracy.
SUMMARY OF THE INVENTION
Accordingly, an object of the present invention is to provide an impeller for a circumferential current pump which can solve the disadvantages in the prior arts mentioned above, and a method of forming the same.
In accordance with a first aspect of the present invention, there is provided an impeller for a circumferential current pump which is provided with a plurality of vane grooves in an outer peripheral side of a synthetic resin disc-like member rotated by a motor and is rotatably received within a substantially disc-like space formed between a pump casing and a pump cover, wherein a recess portion having a predetermined radius around a center of rotation is formed on at least one of one side surface opposing to the pump casing of the disc-like member and another side surface opposing to the pump cover. Further, the structure is characterized in that a ratio (L/2t) between the sum (t
1
+t
2
=2t) of a gap (t
1
) between the one side surface and the pump casing and a gap (t
2
) between the another side surface and the pump cover, and a size (L=R
0
−H−R
1
) obtained by subtracting a radial groove length (H) of the vane groove and a radial size (R
1
) of the recess portion from a radial size (R
0
) of the disc-like member satisfies a relation 66≦(L/2t). In this case, the recess portion includes a substantially disc-like recess portion around a center of rotation of the disc-like member and a substantially annular recess portion around a center of rotation of the disc-like member.
In accordance with the present invention having the structure mentioned above, since it is possible to make the size (L) of the side surface functioning as a seal portion as small as possible, it is possible to form the side surface functioning as the seal portion at a high accuracy only in accordance with an injection molding. Therefore, in accordance with the present invention, a polishing of the impeller side surface is not required, so that it is possible to reduce a process and labor for producing the impeller. Further, in accordance with the present invention, as mentioned above, since it is possible to form the side surface functioning as the seal portion of the impeller at a high accuracy, it is possible to make the gap sizes (t
1
and t
2
) smaller than those of the third prior art.
In accordance with a second aspect of the present invention, there is provided an impeller for a circumferential current pump which is provided with a plurality of vane grooves in an outer peripheral side of a synthetic resin disc-like member rotated by a motor and is rotatably received within a substantially disc-like space formed between a pump casing and a pump cover. Then, the impeller for the circumferential current pump is structured such that a recess portion having a predetermined radius around a center of rotation is formed on at least one of one side surface opposing to the pump casing of the disc-like member and another side surface opposing to the pump cover, and a plurality of grooves extending in a radial direction within the recess portion are formed in a radial shape.
In accordance with the present invention having the structure mentioned above, a plurality of grooves are formed in a radial shape so as to reduce a solid portion in the recess portion, whereby a cooling efficiency at a time of injection molding can be increased, a cycle time for the injection molding can be reduced, and a deformation of a whole of the impeller due to a molding shrinkage (sink mark). Further, in accordance with the present invention, since a plurality of grooves are formed
Sakamoto Yasuyuki
Takeuchi Yoichi
Tatsuzawa Naotaka
Bachman & LaPointe P.C.
Enplas Corporation
Look Edward K.
McCoy Kimya N.
LandOfFree
Impeller for circumferential current pump and method of... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Impeller for circumferential current pump and method of..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Impeller for circumferential current pump and method of... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2868576