U.S. patent application number 14/232119 was filed with the patent office on 2014-06-19 for fuel pump.
This patent application is currently assigned to MITSUBISHI ELECTRIC CORPORATION. The applicant listed for this patent is Yutaro Hamatani. Invention is credited to Yutaro Hamatani.
Application Number | 20140169960 14/232119 |
Document ID | / |
Family ID | 48081489 |
Filed Date | 2014-06-19 |
United States Patent
Application |
20140169960 |
Kind Code |
A1 |
Hamatani; Yutaro |
June 19, 2014 |
FUEL PUMP
Abstract
There is provided a fuel pump (10) which includes an impeller
(20) in a disk-like shape; a casing (18) comprised of a pump cover
(14) and a pump body (16) that rotatably accommodate the impeller;
and a motor section (70) that drives to rotate the impeller;
wherein, on at least one of seal portions of the casing (18) and in
its place facing to a series of recesses (20b,20c) of the impeller,
a recessed shape (35,36) in a micron order is formed in expectation
of a swelling amount of the series of recesses (20b,20c) of the
impeller (20).
Inventors: |
Hamatani; Yutaro;
(Chiyoda-ku, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Hamatani; Yutaro |
Chiyoda-ku |
|
JP |
|
|
Assignee: |
MITSUBISHI ELECTRIC
CORPORATION
Chiyoda-ku, Tokyo
JP
|
Family ID: |
48081489 |
Appl. No.: |
14/232119 |
Filed: |
October 13, 2011 |
PCT Filed: |
October 13, 2011 |
PCT NO: |
PCT/JP2011/073514 |
371 Date: |
January 10, 2014 |
Current U.S.
Class: |
415/230 |
Current CPC
Class: |
F04D 29/026 20130101;
F04D 29/086 20130101; F04D 29/0413 20130101; F04D 29/188 20130101;
F04D 5/002 20130101; F04D 29/051 20130101; F05D 2300/43
20130101 |
Class at
Publication: |
415/230 |
International
Class: |
F04D 29/08 20060101
F04D029/08 |
Claims
1. A fuel pump (10) which includes an impeller (20) in a disc-like
shape; a casing (18) comprising a pump cover (14) and a pump body
(16) that rotatably accommodate the impeller; and a motor section
(70) that drives to rotate the impeller, wherein, on each of front
and back faces of the impeller (20), a series of recesses (20b,20c)
being repeated in a circumferential direction is formed in a region
that extends along the circumferential direction with a given
distance apart inside from an outer periphery, wherein, on the pump
cover (14) facing to the front face of the impeller, a first groove
(31) is formed that extends in a region facing to the series of
recesses (20c) of the impeller, from an upstream end (31a) to a
downstream end (31b), wherein, on the pump body (16) facing to the
back face of the impeller, a second groove (30) is formed that
extends in a region facing to the other series of recesses (20b) of
the impeller, from an upstream end (30a) to a downstream end (30b),
wherein, in the casing (18), there are formed a fuel discharge
opening (41) that communicates between near the downstream end
(31b) of the first groove (31) and an outside of the casing (18),
and a fuel suction opening (40) that communicates between near the
upstream end (30a) of the second groove (30) and an outside of the
casing (18), and wherein, seal portions are provided, as viewed in
a rotating direction of the impeller, between the upstream end and
the downstream end of the first groove (31) on the pump cover (14)
and between the upstream end and the downstream end of the pump
body (16), respectively, said fuel pump characterized in that, on
at least one of the seal portions of the casing (18) and in its
place facing to the series of recesses (20b,20c) of the impeller, a
recessed shape (35,36) in a micron order is formed in expectation
of a swelling amount of said series of recesses (20b,20c) of the
impeller (20).
2. The fuel pump of claim 1, characterized in that, on each of the
pump cover (14) and the pump body (16), the recessed shape (35,36)
is formed.
3. The fuel pump of claim 1, characterized in that the series of
recesses (20b,20c) of the impeller (20) is shaped in a recessed
shape (50a,50b) in expectation of the swelling amount thereof.
4. A fuel pump (10) which includes an impeller (20) in a disc-like
shape; a casing (18) comprising a pump cover (14) and a pump body
(16) that rotatably accommodate the impeller; and a motor section
(70) that drives to rotate the impeller, wherein, on each of front
and back faces of the impeller (20), a series of recesses (20b,20c)
being repeated in a circumferential direction is formed in a region
that extends along the circumferential direction with a given
distance apart inside from an outer periphery, wherein, on the pump
cover (14) facing to the front face of the impeller, a first groove
(31) is formed that extends in a region facing to the series of
recesses (20c) of the impeller, from an upstream end (31a) to a
downstream end (31b), wherein, on the pump body (16) facing to the
back face of the impeller, a second groove (30) is formed that
extends in a region facing to the other series of recesses (20b) of
the impeller, from an upstream end (30a) to a downstream end (30b),
wherein, in the casing (18), there are formed a fuel discharge
opening (41) that communicates between near the downstream end
(31b) of the first groove (31) and an outside of the casing (18),
and a fuel suction opening (40) that communicates between near the
upstream end (30a) of the second groove (30) and an outside of the
casing (18), and wherein, seal portions are provided, as viewed in
a rotating direction of the impeller, between the upstream end and
the downstream end of the first groove (31) on the pump cover (14)
and between the upstream end and the downstream end of the pump
body (16), respectively, said fuel pump characterized in that the
series of recesses (20b,20c) of the impeller (20) is shaped in a
recessed shape (50a,50b) in expectation of a swelling amount
thereof.
Description
TECHNICAL FIELD
[0001] This invention relates to a fuel pump, and in detail,
relates to a fuel pump having an impeller and a pump casing that
rotatably accommodates the impeller.
BACKGROUND ART
[0002] Fuel pumps are known as devices for supplying a fuel in a
fuel tank to an internal combustion engine (for example, a vehicle
engine etc.). The fuel pumps of this type generally have a pump
section. The pump section includes a casing and an impeller in a
nearly disc-like shape that is rotatably accommodated in the
casing. On a surface of the impeller facing to a fuel suction side,
a blade groove portion is circularly formed along the outer
periphery of the impeller. On a surface of the impeller facing to a
fuel discharge side, another blade groove portion is formed at a
place corresponding to the blade groove portion formed at the
suction side of the impeller. These groove portions formed on the
surfaces at the suction side and at the discharge side of the
impeller, are communicated with each other through their
bottoms.
[0003] On respective inner faces of the casing that are facing to
the suction side and the discharge side of the impeller, pump
passage are formed each extending from an upstream end to a
downstream end along a rotating direction of the impeller in a
region corresponding to each blade groove portion formed on the
impeller. The upstream end of the suction-side pump passage is
communicated with the outside of the casing through a fuel suction
opening, and the downstream end of the discharge-side pump passage
is communicated with the outside of the casing through a fuel
discharge opening.
[0004] In the fuel pumps thus configured, upon rotation of the
impeller, the fuel is sucked in the pump casing through the suction
opening and the sucked fuel is introduced into the blade groove
portions of the impeller and the pump passages. A centrifugal force
due to rotation of the impeller acts on the fuel sucked in the pump
casing. The fuel sucked in the pump casing flows along the pump
passages to the downstream side thereof while being pressurized by
the centrifugal force of the impeller, and is then discharged to
the outside of the pump casing from the discharge opening.
[0005] In such fuel pumps, in order to prevent a reduction in
discharge efficiency of the pump due to a leakage loss emerging
through a clearance in contact with the surface of the impeller and
between the surface and a slidable face of a pump cover or a pump
base, clearances in the thrust direction are made extremely small.
Thus, when the fuel pressure in a pump chamber is increasing toward
the pump chamber outlet from the fuel suction opening by the
rotation of the blade groove portions, the impeller rotates while
making contact with a place of the pump casing facing to the pump
chamber outlet because of unbalanced pressure between at around the
pump chamber outlet in the pump casing and at around the fuel
suction opening in the pump casing.
[0006] Thus, in order to prevent such a contact, it is known to
form, near the outlet of the pump on the slidable face of the pump
casing, a larger clearance than the small clearance between the
surface of the impeller and the pump casing, to thereby make a
slipping portion (see, for example, Patent Document 1).
CITATION LIST
Patent Document
[0007] Patent Document 1: Japanese Patent Application Laid-open No.
H05(1993)-187382
SUMMARY OF THE INVENTION
Problems to be Solved by the Invention
[0008] According to the experiment and investigation by the
inventor, it has been confirmed that a dimensional deformation of
the impeller occurs significantly at a series of recesses thereof.
Thus, in order to prevent the contact between the pump casing and
the impeller, it is hard to say that it is fully enough to provide
only the slipping portion shown in Patent Document 1.
[0009] This invention has been made in consideration of the above
situation, and an object thereof is to provide a fuel pump that has
a simple and low cost configuration, and that prevents increase in
rotational resistance of the impeller and occurrence of trouble in
the pump chamber, such as locking, to thereby achieve both ensuring
the reliability and keeping the pump performance.
Means for Solving the Problems
[0010] A fuel pump according to the invention is configured to
include: an impeller in a disc-like shape; a casing comprising a
pump cover and a pump body that rotatably accommodate the impeller;
and a motor section that drives to rotate the impeller; wherein, on
each of front and back faces of the impeller, a series of recesses
being repeated in a circumferential direction is formed in a region
that extends along the circumferential direction with a given
distance apart inside from an outer periphery; wherein, on the pump
cover facing to the front face of the impeller, a first groove is
formed that extends in a region facing to the series of recesses of
the impeller, from an upstream end to a downstream end; wherein, on
the pump body facing to the back face of the impeller, a second
groove is formed that extends in a region facing to the other
series of recesses of the impeller, from an upstream end to a
downstream end; wherein, in the casing, there are formed a fuel
discharge opening that communicates between near the downstream end
of the first groove and an outside of the casing, and a fuel
suction opening that communicates between near the upstream end of
the second groove and an outside of the casing; and wherein, seal
portions are provided, as viewed in a rotating direction of the
impeller, between the upstream end and the downstream end of the
first groove on the pump cover and between the upstream end and the
downstream end of the pump body, respectively; said fuel pump
comprising, on at least one of the seal portions of the casing and
in its place facing to the series of recesses of the impeller, a
recessed shape in a micron order formed in expectation of a
swelling amount of said series of recesses of the impeller.
Effect of the Invention
[0011] According to the fuel pump of the invention, it is possible
to provide a fuel pump that has a simple and low cost
configuration, and that prevents increase in rotational resistance
of the impeller and occurrence of trouble in the pump chamber, such
as locking, to thereby achieve both ensuring the reliability and
keeping the pump performance.
[0012] The foregoing and other objects, features, and advantages of
the present invention will become more apparent from the following
detailed description of the embodiment and the illustration of the
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] FIG. 1 is a longitudinal cross-sectional view showing a
whole configuration of a fuel pump of Embodiment 1 of the
invention.
[0014] FIG. 2 is a enlarged longitudinal cross-sectional view of a
pump section shown in FIG. 1.
[0015] FIG. 3 is a top view of an impeller according to Embodiment
1 of the invention.
[0016] FIG. 4 is a top view of a pump body, viewed from the side of
the impeller, according to Embodiment 1 of the invention.
[0017] FIG. 5 is a top view of a pump cover, viewed from the side
of the impeller, according to Embodiment 1 of the invention.
[0018] FIG. 6 is a partial cross-sectional view of the pump section
12 according to Embodiment 1 of the invention.
MODES FOR CARRYING OUT THE INVENTION
Embodiment 1
[0019] Embodiment 1 of the invention will be described with
reference to FIG. 1 through FIG. 6. Note that, in the respective
figures, the same symbols represent the same or equivalent
parts.
[0020] What is characterized by the invention is summarized that,
on a seal portion that is provided on an inner slidable face of a
casing facing to a series of blade grooves of an impeller, from a
fuel discharge opening to a fuel suction opening as viewed in a
rotating direction, a recessed shape along a nearly circular
circumference is formed that is resulted from further broadening a
clearance by a micron order.
[0021] FIG. 1 is a longitudinal cross-sectional view showing a
whole configuration of a fuel pump of Embodiment 1 of the
invention. As shown in FIG. 1, the fuel pump 10 is configured with
a motor section 70 and a pump section 12.
[0022] The motor section 70 is provided with a housing 72, a motor
cover 73, magnets 74,75, and a rotor 76. The housing 72 is formed
in a nearly cylindrical shape. The motor cover 73 is fixed to the
housing 72 by caulking inwardly an upper end 72a of the housing 72
(up and down in FIG. 1 correspond to up and down of the fuel pump
10, here). On the motor cover 73, a discharge port 73a is formed
that is open upward. The magnets 74,75 are fixed to an inner wall
of the housing 72. The rotor 76 has a main body 77 composed of a
laminated core and a coil, etc., and a shaft 78 penetrating up and
down through the main body 77. An upper end portion 78a of the
shaft 78 is rotatably mounted to the motor cover 73 byway of a
bearing 81. A lower end portion 78b of the shaft 78 is rotatably
mounted to a pump cover 14 of the pump section 12 by way of a
bearing 82. Regarding the motor section 70, since its configuration
is similar to that of the conventional fuel pump, a more detailed
description thereof is omitted here.
[0023] FIG. 2 shows a selectively enlarged view of the pump section
shown in FIG. 1.
[0024] The pump section 12 is provided with a casing 18 and an
impeller 20.
[0025] As shown in FIG. 3, the impeller 20 is nearly in a disc-like
shape. On a fuel-suction-side face of the impeller 20, a first
series of blade grooves 20b successively arranged in a
circumference direction is formed circularly with a given distance
apart from an outer periphery face 20e. That is, the first series
of blade grooves 20b is apart from the outer periphery face 20e of
the impeller 20 by an outer periphery wall 20d of the impeller 20.
On a fuel-discharge-side face of the impeller 20, a second series
of blade grooves 20c successively arranged in a circumference
direction is formed circularly in a place corresponding to the
first series of blade grooves 20b formed on the fuel-suction-side
face of the impeller 20 (that is, in a region being apart by a
given distance from the outer periphery face 20e). Note that the
bottoms of the first series of blade grooves 20b and the second
series of blade grooves 20c are communicated with each other
through communication openings (omitted from the figure). At the
central portion of the impeller 20, an engaging hole 20a is formed
that is a nearly D-letter like form in a cross section
perpendicular to the shaft direction and that penetrates through
the impeller in the thickness direction. The shaft 78 is engaged
with in the engaging hole 20a. Upon energizing the coil of the
rotor 77, the shaft 78 rotates so that the impeller 20 rotates.
[0026] The casing 18 comprises a combination of the pump cover 14
and a pump body 16. As shown in FIG. 2 and FIG. 5, in an
impeller-side face of the pump cover 14 (that is, its lower-side
face in FIG. 1), a concave portion 14a is formed that is circular
in planar view. The diameter of the concave portion 14a is
approximately the same as the diameter of the impeller 20, and the
depth of the concave portion 14a is approximately the same as the
thickness of the impeller 20.
[0027] The impeller 20 is rotatably fitted in the concave portion
14a.
[0028] On a bottom face of the concave portion 14a of the pump
cover 14 (hereinafter, this face may be referred to as lower face
of the pump cover), a second pump passage like a groove is formed
that extends along a circumference direction in a region facing to
the second series of blade grooves 20c of the impeller 20. An
upstream end 31a of the second pump passage 31 is built near a
place facing to an upstream end 30a of a first pump passage 30 to
be described later.
[0029] At a downstream end 31b of the second pump passage 31, a
fuel discharge opening 41 is formed.
[0030] The fuel discharge opening 41 extends from the second pump
passage 31 to an upper face of the pump cover 14 (upper face in
FIG. 1), to thereby communicate between the second pump passage 31
and the outside of the casing 18 (in exact detail, the inside of
the housing 72).
[0031] Between the impeller 20 and the concave portion 14a of the
pump cover 14, a little clearance A in the shaft direction shown in
FIG. 6 is formed, and between the impeller 20 and an inner
circumference face 14b of the concave portion 14a of the pump cover
14, a little clearance B in a radial direction shown in FIG. 6 is
formed. These clearances A and B are provided in order for the
impeller 20 to rotate smoothly.
[0032] It is noted that, although the clearances between the
impeller 20 and the pump cover 14 in the figure are shown
schematically to be too wide, they are actually fallen in the
degree of from several micrometers to several tens micron
meters.
[0033] On an upper face of the pump body 16, a first pump passage
30 like a groove is formed that extends along a circumference
direction in a region facing to the first series of blade grooves
20b of the impeller 20. At the upstream end 30a of the first pump
passage 30, a fuel suction opening 40 is provided. In between the
upstream end 30a and a downstream end 30b of the first pump passage
30, a vapor vent hole 30c is formed that penetrates up and down (up
and down in FIG. 1) through the pump body 16. At the central
portion of the pump body 16, a concave place 16b is formed, and in
the concave place 16b, a thrust bearing 33 is disposed in the same
axis as the shaft 78.
[0034] The thrust bearing 33 receives and bears the thrust load of
the rotor 76.
[0035] The casing 18 comprised of the pump cover 14 and the pump
body 16 is fixed to the housing 72 by caulking inwardly a lower end
72b of the housing 72, in a state where the impeller 20 is embedded
in the concave portion 14a of the pump cover 14.
[0036] Meanwhile, in a state of the casing 18 fixed to the housing
72, the lower end portion 78b of the shaft 78 is being inserted and
fitted in the engaging hole 20a of the impeller 20 at a location
lower than the location where being supported by the bearing 82.
Between the lower end of the shaft 78 and the pump body 16, the
thrust bearing 33 is interposed.
[0037] According to the fuel pump 10 configured as described above,
when a current flows through the rotor 76 so that the impeller 20
rotates, the fuel in a fuel tank (omitted from the figures) is
sucked in the casing 18 through the fuel suction opening 40. The
fuel sucked in the casing 18 firstly flows in the upstream end 30a
of the first pump passage 30. As shown in FIG. 6, the fuel having
flowed in the first pump passage 30 forms a swirling flow S between
the first pump passage 30 and the first series of blade grooves 20b
by the rotation of the impeller 20, to thereby be pressurized.
Further, the fuel having flowed in the first pump passage 30 flows
along the first pump passage 30 from the upstream end 30a toward
the downstream end 30b while being pressurized by the rotation of
the impeller. Then, the fuel discharged to the motor section 70
from the fuel discharge opening 41 formed at the downstream end of
the second pump passage 31, flows inside the motor section 70, and
then discharged to the outside of the fuel pump 10 from the
discharge port 73a formed on the motor cover 73.
[0038] The aforementioned little clearance A in the shaft direction
shown in FIG. 6, is one of the factors that largely affect the
discharge performance of the fuel pump 10. That is, when the
clearance becomes broader, the swirling flow S is impaired from
flowing smoothly and at the same time, a leakage loss in the casing
18 becomes increased, which results in reduction of the discharge
amount of fuel discharged from the fuel discharge opening 41.
Namely, keeping and controlling the clearance as little as
possible, is an extremely important issue for keeping the discharge
performance of the pump. Meanwhile, the impeller 20, which is made
of a thermosetting or thermoplastic resin or like resin material,
is known to cause its dimensional change (swelling) due to moisture
absorption because the impeller 20 is generally used in its
immersed state in the fuel as described above, at all times.
[0039] When an amount of swelling due to moisture absorption
becomes close to the clearance A formed in the shaft direction, the
rotational abrasion resistance becomes increased because the
rotating motion is obstructed by an interference between the
impeller and the casing, thereby causing reduction in the discharge
efficiency of the fuel pump. If the impeller 20 further swells
beyond the set clearance A, there is a concern that the pump
chamber results in its locking in the worst case. In such a
background, it is necessary to set and control the clearance to be
little to the extent of not causing the locking etc., in
expectation of the impeller's swelling due to immersion in the
fuel.
[0040] The impeller 20 with a shape having an outer ring portion
20g as shown in FIG. 3, and in particular, made of a thermosetting
resin, has a characteristic that the swelling amount at a blade
portion 20f is larger than those at the other portions (a planar
portion, the outer periphery portion 20e). In Embodiment 1, the
above characteristic is focused, so that, on a portion of each
slidable face inside the casing 18, that is facing to the blade
portion 20f of the impeller, a recessed shape is formed that
incorporates an expected swelling amount in advance.
[0041] Specifically, with respect to the pump passages 30,31 in
nearly C-letter like shape formed on the slidable faces of the pump
body 16 and the pump cover 14, the recessed shapes 35,36 in a
micron order each incorporating an expected swelling amount of the
impeller 20 are formed along the lines extending from these
passages in the circumference direction, in other words, in seal
portions provided between the upstream end 30a and the downstream
end 30b and between the upstream end 31a and the downstream end 31b
of the pump passages 30 and 31, respectively, so that the
clearances are partially enlarged.
[0042] According to the fuel pump of Embodiment 1 of the invention
configured as described above, even when the blade portion 20f
swells, it is possible to prevent increase in rotational resistance
of the impeller 20 or occurrence of trouble in the pump chamber,
such as locking. At the same time, since the region where the
clearance is enlarged is limited to a necessary region, there is no
large reduction in pump-discharge performance; namely, it is
possible to achieve both ensuring the reliability and keeping the
pump performance.
[0043] It is noted that the foregoing description is given to the
case where the recessed shapes 35,36 formed on the inner faces of
the casing 18, are formed on the pump body 16 and the pump cover
14, respectively; however, the recessed shape may be formed on only
either one of them.
[0044] Further, when recessed shapes 50a,50b each incorporating an
expected swelling amount are formed, contrary to the foregoing
embodiment, on the impeller side as shown in FIG. 6, a similar
effect can be expected.
[0045] Further, in the fuel pump 10 of the foregoing Embodiment 1,
since the recessed shapes are formed only on the pump body 16 and
the pump cover 14, or on the impeller 20, it is possible to use
conventional components (parts) for the other portions.
[0046] Although specific examples of the invention have been
detailed using Embodiment 1 as described above, they are merely
examples and do not limit the scope of the claims. The technologies
described in the claims include various modifications or
alternations of the specific examples that are exemplified
above.
[0047] Moreover, the technical components described in the present
description or the drawings exert technical usefulness solely or in
various combinations, and should not be limited to the combinations
described in the claims at the time of filing of this application.
Further, the technologies exemplified in the present description or
the drawings can accomplish a plurality of objectives at the same
time, and are said to have a technical usefulness simply by
achieving one of the objectives.
INDUSTRIAL APPLICABILITY
[0048] The invention is well-suited to be applied to a fuel pump
for supplying a fuel in a fuel tank to an internal combustion
engine (for example, a vehicle engine etc.,)
DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
[0049] 10: fuel pump, 12: pump section, 14: pump cover, 16: pump
body, 18: casing, 20: impeller, 20b: first series of blade grooves
(series of recesses), 20c: second series of blade grooves (series
of recesses), 30,31: pump passages, 30a: upstream end of the pump
passage 30, 30b: downstream end of the pump passage 30, 31a:
upstream end of the pump passage 31, 31b: downstream end of the
pump passage 31, 35: recessed shape (pump-body side), 36: recessed
shape (pump-cover side), 40: fuel suction opening, 41: fuel
discharge opening, 50a,50b: recessed shapes (impeller side), 70:
motor section, 72: housing, 73: motor cover, 74,75: magnets, 76:
rotor, 78: shaft.
* * * * *