U.S. patent application number 10/810883 was filed with the patent office on 2004-09-30 for motor driven fuel pump having impeller.
This patent application is currently assigned to Denso Corporation. Invention is credited to Kondo, Fumio, Koseki, Sachiyo, Koyama, Hideki, Oi, Kiyotoshi.
Application Number | 20040191096 10/810883 |
Document ID | / |
Family ID | 32985299 |
Filed Date | 2004-09-30 |
United States Patent
Application |
20040191096 |
Kind Code |
A1 |
Koyama, Hideki ; et
al. |
September 30, 2004 |
Motor driven fuel pump having impeller
Abstract
A fuel pump for an internal combustion engine includes a
suction-side cover having a fuel inlet, an exhaust-side cover
having a fuel outlet, an electric motor, a pump casing disposed
between the electric motor and the suction-side cover, an impeller
disposed between the suction-side cover and the pump casing to be
rotated by the electric motor, and a cylindrical housing for
accommodating the suction-side cover, the pump casing and the
impeller. The suction-side cover is made of a resinous member that
has a shoulder having a round surface in contact with a portion of
the cylindrical housing that is clinched at the shoulder.
Inventors: |
Koyama, Hideki;
(Okazaki-city, JP) ; Kondo, Fumio; (Nagoya-city,
JP) ; Koseki, Sachiyo; (Nagoya-city, JP) ; Oi,
Kiyotoshi; (Anjo-city, JP) |
Correspondence
Address: |
NIXON & VANDERHYE, PC
1100 N GLEBE ROAD
8TH FLOOR
ARLINGTON
VA
22201-4714
US
|
Assignee: |
Denso Corporation
Aichi-pref.
JP
|
Family ID: |
32985299 |
Appl. No.: |
10/810883 |
Filed: |
March 29, 2004 |
Current U.S.
Class: |
417/423.14 |
Current CPC
Class: |
F04D 29/406 20130101;
F04D 5/002 20130101; F05D 2260/36 20130101 |
Class at
Publication: |
417/423.14 |
International
Class: |
F04B 017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 28, 2003 |
JP |
2003-90910 |
Claims
What is claimed is:
1. A fuel pump for supplying fuel to an internal combustion engine
comprising a suction-side cover having a fuel inlet, an
exhaust-side cover having a fuel outlet, an electric motor disposed
between said suction-side cover and said exhaust-side cover, a pump
casing disposed between said electric motor and said suction-side
cover, a passage member having a pressure boosting passage disposed
between said suction-side cover and said pump casing, an impeller
disposed in the pressure boosting passage to be rotated by said
electric motor, and a cylindrical housing for accommodating said
suction-side cover, said pump casing and said impeller, wherein
said suction-side cover comprises a resinous member that has a
shoulder having a round surface in contact with a portion of said
cylindrical housing that is clinched at said shoulder.
2. The fuel pump as claimed in claim 1, wherein said round surface
is disposed at a peripheral surface of said suction-side cover away
from said pump casing.
3. The fuel pump as claimed in claim 2, wherein the radius of said
round corner is 2 mm or longer.
4. The fuel pump as claimed in claim 2, wherein the portion of said
cylindrical housing that is clinched has a surface formed by a
punch that has a concave pressing surface.
5. The fuel pump as claimed in claim 1, wherein said shoulder has a
thickness between 4 mm and 5 mm.
6. A fuel pump for supplying fuel to an internal combustion engine
including a suction-side cover having a fuel inlet, a pump casing,
an impeller disposed between said suction-side cover and said pump
casing and a cylindrical housing for accommodating said
suction-side cover, said pump casing and said impeller, wherein:
said suction-side cover has a shoulder having a round surface in
contact with a portion of said cylindrical housing that is clinched
at said shoulder; said round surface has a radius of 2 mm or
longer; and said shoulder has a thickness between 4 mm and 5 mm.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application is based on and claims priority from
Japanese Patent Application 2003-90910, filed Mar. 28, 2003, the
contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a motor driven fuel pump
mounted in a fuel tank of an internal combustion engine
(hereinafter referred to as engine).
[0004] 2. Description of the Related Art
[0005] A fuel pump that has a fuel pressurizing passage and an
impeller to boost pressure of fuel is well known and disclosed, for
example, in JP-B2-3052623. Such a fuel pump is comprised of a
suction-side cover in which a portion of the fuel pressurizing
passage is formed.
[0006] In order to reduce the production cost and weight, many
trials to change material of the suction-side cover from a metal to
a resin has been made. However, if a resinous suction-side cover 94
is fixed to a cylindrical metal housing 92 by clinching the edge of
the housing 92 as shown in FIG. 7, the resinous suction-side cover
94 easily deforms, resulting in that the suction-side cover 94
interferes with an impeller 96. The resinous suction-side cover 94
may creep under continuous pressure from the housing in a long
period of time, resulting in loosening of the suction-cover.
SUMMARY OF THE INVENTION
[0007] Therefore, an object of the invention is to provide an
inexpensive and lightweight fuel pump that has a resinous
suction-side cover and is free from the above described
problem.
[0008] According to a feature of the invention, a fuel pump for an
internal combustion engine includes a suction-side cover having a
fuel inlet, an exhaust-side cover having a fuel outlet, an electric
motor, a pump casing disposed between the electric motor and the
suction-side cover, a passage member having a pressure boosting
passage disposed between the suction-side cover and the pump
casing, an impeller disposed in the pressure boosting passage to be
rotated by the electric motor and a cylindrical housing for
accommodating the suction-side cover, the pump casing and the
impeller. In the above fuel pump, the suction-side cover is made of
a resinous member that has a shoulder having a round surface in
contact with a portion of the cylindrical housing that is clinched
at the shoulder.
[0009] Therefore, the stress concentration on the suction-side
cover becomes smaller and creeping of the suction-side cover can be
prevented. As a result, the suction-side cover can be prevented
from loosening.
[0010] In the above described fuel pump, the round surface is
preferably disposed at a peripheral surface of the suction-side
cover away from the pump casing. Further, the radius of the round
corner is preferably 20 mm or longer. The portion of the
cylindrical housing that is clinched may have a surface formed by a
punch that has a concave pressing surface. It is more preferable
that the shoulder has a thickness between 4 mm and 5 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Other objects, features and char acteristics of the present
invention as well as the functions of related parts of the present
invention will become clear from a study of the following detailed
description, the appended claims and the drawings. In the
drawings:
[0012] FIG. 1 is an axial cross -sectional view of a fuel pump
according to a preferred embodiment of the invention;
[0013] FIGS. 2A, 2B and 2C respectively illustrate a front view of
a suction-side cover, a cross-sectional view of the suction-side
cover cut along line IIB-IIB in FIG. 2A, and a rear view of the
suction-side cover;
[0014] FIG. 3 illustrates a step of fixing the suction-side cover
to a housing of the fuel pump;
[0015] FIG. 4 is a graph showing a relationship between the amount
of deformation of the suction-side cover and the radius of a
pressing surface of a punch for fixing the suction-side cover to
the housing of the fuel pump;
[0016] FIG. 5 is a graph showing the amount of deformation of the
suction-side cover fixed by a punch having a curved surface;
[0017] FIG. 6 is a graph showing the amount of deformati on of the
suction-side cover fixed by a punch having a flat conical surface;
and
[0018] FIG. 7 is a schematic diagram showing a conventional step of
fixing a suction-side cover to a cylindrical cover.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0019] A fuel pump according to a preferred embodiment of the
invention will be described with reference to the appended
drawings.
[0020] As shown in FIG. 1, a fuel pump 10 according to a preferred
embodiment of the invention is a so-called in-tank type fuel pump
to be mounted in a fuel tank of a vehicle.
[0021] The fuel pump 10 includes a cylindrical metal housing 22,
which has a pair of annular steps 20, 30 at the inside surface
thereof. The housing 22 accommodates an exhaust-side cover 14, an
electric motor 46, a pump casing 40, an impeller 37, a suction-side
cover 36, etc.
[0022] The exhaust-side cover 14, which has a front surface and a
shoulder portion, is fitted to the housing 22 so that the front
surface engages the annular step 20. The housing 22 has one end
through which the exhaust-side cover 14 is inserted and fixed by
clinching the edge of the one end to hold a shoulder portion of the
exhaust-side cover 14, thereby positioning the exhaust-side cover
14 between the annular step 20 and the one end. The electric motor
46 has a rotary shaft 45, which is supported by the exhaust-side
cover 14 via a bearing 16. The housing 22 has an inner wall, on
which four semi-cylindrical permanent magnets 44 are disposed in a
circular line. The permanent magnets 44 are magnetized in radial
directions to alternately form N and S poles in the circumferential
direction.
[0023] The electric motor 46 has an armature 42 which is rotatably
accommodated in the housing 22 and a commutator 18 which is fixed
to one end of the armature 42. The armature 42 includes a magnetic
core 24 to which the rotary shaft 45 is force-fitted and a
plurality of coils 28 each of which is wound around a bobbin 26.
The commutator 18 has a plurality of commutator segments each of
which is connected to one of the coils 28.
[0024] The pump casing 40 is inserted into the other end of the
housing 22 and engages the annular step 30 by an inside surface
thereof. The pump casing 40 has an annular peripheral portion at an
outside surface thereof and a center hole to which another bearing
38 is fitted. The annular peripheral portion engages the
suction-side cover 36 at the inside surface of the suction-side
cover 36. The suction-side cover 36 has a shoulder 34 at the
peripheral portion, which is held by a portion of the other end of
the housing 22 that is clinched to fix the suction-side cover 36 to
the housing 22, thereby positioning the pump casing 40 between the
annular step 30 and the suction-side cover 36. A pressure boosting
passage 32 is formed at a space between the inside surface of the
suction- side cover 36 and the outside surface of the pump casing
40 so that the impeller 37 can rotate therein. The impeller 37 is a
disk member that has a plurality of blade-ditches on the periphery
thereof.
[0025] When the electric motor 46 rotates along with the rotary
shaft 45 to rotate the impeller 37, fuel that is supplied from the
fuel inlet to the pressure boosting passage 32 is pressurized and
discharged from the pressure boosting passage 32 to the inside of
the electric motor 46 through a connecting passage 29. The
discharged fuel cools the electric motor 46 and flows out from the
fuel outlet 12 to be supplied to an engine.
[0026] The suction-side cover 36 is a resinous disk plate that has
a plurality of depressions 54 for preventing mold shrinkage and the
shoulder 34 at its periphery. The suction-side cover 36 also has a
C-shaped groove 50 that is a portion of the pressure boosting
passage. The fuel inlet 52 is formed at an end of the C-shaped
groove 50, and a vapor purging hole 48 is also formed in the
C-shaped groove 50.
[0027] The suction-side cover 36 has a thickness of t1, such as 7
mm. The shoulder 34 has a thickness of t2 and a round corner of
more than 2 mm in radius r2. The round corner provides a contact
surface in contact with the end of the housing 22. The more the
radius of the round corner increases, the less stress concentration
on the contact surface. As the stress concentration becomes
smaller, creeping of the suction-side cover 36 can be prevented or
reduced. As a result, the suction-side cover 36 can be prevented
from loosening. However, as the suction-side cover 36 becomes
thicker, the total length of the fuel pump 10 increases. Therefore,
the ratio of the thickness t2 of the shoulder 34 to the thickness
t1 of the suction-side cover 34 is preferably between 0.57 and
0.71.
[0028] The suction-side cover 36 is fixed to the housing 22 by a
punch 56, as shown in FIG. 3. The punch 56 has a pressing surface
58 to press the end of the housing 22 against the shoulder 34 of
the suction-side cover 36. The pressing surface 58 inclines to the
center axis of the housing 22 by an inclination angle .alpha.. As
the inclination angle .alpha. increases, the remaining stress to
deform the suction-side cover 36 becomes smaller. However, if the
inclination angle .alpha. becomes larger than 45 degrees, the
housing 22 may buckle. Therefore, the inclination angle .alpha. is
preferably about 30 degrees. The pressing surface is, preferably,
concave that has a radius r1. It may be conical if the inclination
angle.alpha. is appropriate.
[0029] The amount of the deformation of the shoulder 34A relative
to the radius r1 of the concave pressing surface 58 when the
suction-side cover 36 is fixed to the housing 22 at an end that has
a thickness of 0.6 mm was tested to have a result shown in FIG. 4.
If the radius r2 of the contact surface of the shoulder 34 is 1 mm,
the amount of the deformation of the shoulder 34 is smaller in case
the radius r1 of the pressing surface 58 is 2 mm or 3 mm. If the
radius r2 of the contact surface of the shoulder 34 is 2 mm, the
amount of the deformation of the shoulder 34 is smaller in case the
radius r1 of the pressing surface 58 is 4 mm or 5 mm.
[0030] According to the result of an analysis, the following
relationship was found: if the radius r1 of the pressing surface 58
is a length between 1.4 mm and 2.4 mm larger than the sum of the
radius r2 of the shoulder 34 and the thickness of the housing 22,
the deformation due to fixing by clinching becomes minimum; and if
the radius r1 of the concave pressing surface 58 is between 2 and
5, the deformation of the shoulder 34 becomes smaller than the flat
conical pressing surface.
[0031] A result of an analysis of the deformation at two portions
P, Q (shown in FIG. 2B) of the suction-side cover 36 is shown in
FIGS. 5 and 6. When the housing 22 and the shoulder 34 are fixed by
clinching the end of the housing 22, the suction-side cover 36
deforms so that the surface becomes convex in the direction away
from the impeller 37. Therefore, the suction-side cover 36 will not
interfere with the impeller 37. The amount of the deformation when
fixing by the punch having the concave pressing surface was found
smaller than that when fixing by the punch having the flat conical
pressing surface.
[0032] In the foregoing description of the present invention, the
invention has been disclosed with reference to specific embodiments
thereof. It will, however, be evident that various modifications
and changes may be made to the specific embodiments of the present
invention without departing from the scope of the invention as set
forth in the appended claims. Accordingly, the description of the
present invention is to be regarded in an illustrative, rather than
a restrictive, sense.
* * * * *