Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
2001-08-31
2003-02-18
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C123S457000, C123S511000
Reexamination Certificate
active
06520163
ABSTRACT:
REFERENCE TO RELATED APPLICATIONS
This application is based on Japanese Patent Application No. 2000-270265, filed in Japan on Sep. 6, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to an in-tank fuel supply apparatus for installation in a fuel tank of a vehicle, for example. In particular, it relates to an in-tank fuel supply apparatus in which a fuel pump, a fuel filter, a pressure regulator, and a check valve are part of an assembly which can be installed in a fuel tank as a single unit.
2. Description of the Related Art
FIG. 12
is a cross-sectional elevation of a conventional in-tank fuel supply apparatus disclosed in Japanese Published Unexamined Patent Application Hei 11-241659 having a fuel pump, a fuel filter, a pressure regulator, and a check valve combined as part of an assembly for installation in a fuel tank.
FIG. 13
is a schematic illustration of the apparatus of
FIG. 12
, and
FIG. 14
is an enlarged cross-sectional elevation of a conventional pressure regulator which can be used as the pressure regulator of the apparatus of FIG.
12
.
The fuel supply apparatus of
FIGS. 12 and 13
is disposed in a fuel tank
1
and includes a fuel pump
2
, an intake filter
3
disposed upstream of the inlet of the fuel pump
2
, and a fuel filter unit
4
disposed downstream of the discharge port of the fuel pump
2
. A filter element
6
is disposed inside a main housing
5
made from a molded resin. The fuel pump
2
is supported by a downwardly extending lower portion of the main housing
5
. The discharge port of the fuel pump
2
communicates through a connecting pipe with a space within the main housing
5
at an inlet
5
a
on the upstream side of the filter element
6
.
The fuel supply apparatus further includes an upper housing
7
made of a molded resin. After the filter element
6
is inserted into the main housing
5
, the upper housing
7
is sealed to the main housing
5
in an oil tight manner by solvent bonding or other suitable method to enclose the filter element
6
, so that fuel can flow within the fuel filter unit
4
from the inlet
5
a
through the filter element
6
to the outlet
5
b
. The upper end of the upper housing
7
has a flange formed thereon by which the fuel supply apparatus can be mounted on the upper surface of the fuel tank
1
.
The fuel supply apparatus is equipped with a fuel supply passage
8
for carrying fuel from the outlet
5
b
of the fuel filter unit
4
to an unillustrated engine. The fuel supply passage
8
is integrally formed with the upper housing
7
. A check valve
9
is provided in the fuel supply passage
8
for preventing reverse flow of fuel from the engine to the fuel filter unit
4
. The fuel supply passage
8
and the outlet
5
b
are connected to each other by solvent bonding at the same time that the upper housing
7
is sealed in an oil tight manner by solvent bonding to the upper end of the main housing
5
. A pressure regulator
10
is provided for maintaining the pressure of fuel supplied to the engine in a prescribed range. It returns excess fuel which is not supplied to the engine to inside the fuel tank
1
. During normal operation of the fuel supply apparatus, the amount of fuel discharged by the fuel pump
2
is greater than the amount of fuel which is consumed by the engine.
FIG. 13
is a schematic illustration of the fuel supply apparatus of FIG.
12
. This figure shows that the check valve
9
is disposed downstream of the filter element
6
, and that the pressure regulator
10
is mounted on a pipe which branches off the nipple
8
a
of the fuel supply passage
8
downstream of the check valve
9
.
In a fuel supply apparatus of this type, when the fuel pump
2
is operated, liquid fuel is sucked from the interior of the fuel tank
1
by the fuel pump
2
through the intake filter
3
. The fuel is pressurized to 200-700 kPa by the fuel pump
2
, and then it enters the fuel filter unit
4
through the inlet
5
a
. Coarse debris and other contaminants are removed from the fuel by the intake filter
3
, while fine contaminants are removed from the fuel by the filter element
6
in the fuel filter unit
4
. After passing through the filter element
6
, the filtered fuel is discharged from the outlet
5
b
and passes through the fuel supply passage
8
through the check valve
9
to be supplied to the engine. The pressure of the fuel supplied to the engine is maintained in a prescribed range by the pressure regulator
10
, which discharges excess fuel to inside the fuel tank
1
when the pressure in the fuel supply passage
8
exceeds a prescribed level due to an increase in the output of the fuel pump
2
or a decrease in fuel consumption by the engine. The check valve
9
maintains the fuel pressure in the engine when the fuel pump
2
is stopped.
In a fuel supply apparatus like that described above, since the pressure regulator
10
communicates with the fuel supply passage
8
downstream of the check valve
9
, when the fuel pump
2
is stopped, in order to maintain the fuel pressure in the engine, the pressure regulator
10
must have a good ability to maintain a seal between its upstream and downstream sides.
An example of a pressure regulator having a good sealing ability is shown in
FIG. 14
, which is an enlarged cross-sectional elevation of a conventional pressure regulator disclosed in Japanese Published Unexamined Patent Application Hei 5-215048. In this pressure regulator
10
, a movable valve
10
c
which is secured to a spherical bearing
10
b
is mounted on a diaphragm
10
a
for sensing fuel pressure. The valve
10
c
opposes a valve seat
10
d
which communicates with a discharge port.
When the fuel pressure increases to a level such that the force acting upwardly on the diaphragm
10
a
due to fuel pressure exceeds the downwards force exerted by a back pressure spring
10
e
, the diaphragm
10
a
deforms upwards and valve
10
c
separates from the valve seat
10
d
to create a gap. As a result, fuel is discharged through the gap between the valve
10
c
and the valve seat
10
d
, and the fuel pressure on the engine side of the pressure regulator
10
is maintained constant.
When the fuel pressure decreases below a certain level, the valve
10
c
is made to contact the valve seat
10
d
by the force of the back pressure spring
10
e
, and the discharge of fuel from the fuel regulator
10
is stopped. Since the movement due to deformation of the diaphragm
10
a
is not uniform, the valve
10
c
is supported by the spherical bearing
10
b
so as to be able to freely pivot so that the valve
10
c
can intimately contact the valve seat
10
d
and prevent leaks of fuel to the downstream side of the pressure regulator
10
to maintain the fuel pressure in the fuel supply passage
8
.
While the pressure regulator
10
of
FIG. 14
has good sealing performance, it has the drawback that it is expensive to manufacture due to the need to perform high precision finishing of the spherical bearing
10
b
, the valve
10
c
, and the valve seat
10
d
. Furthermore, the diameter of the diaphragm
10
a
must be fairly large in order to give the valve
10
c
good durability and in order to support the valve
10
c
in a manner such that it can freely pivot, and this leads to an increase in the outer dimensions of the pressure regulator
10
, which is an impediment to obtaining a compact fuel supply apparatus.
SUMMARY OF THE INVENTION
The present invention provides a fuel supply apparatus which can employ an inexpensive pressure regulator having a simple and compact structure.
The present invention also provides a fuel supply apparatus which enables an engine which is supplied fuel by the fuel supply apparatus to be quickly restarted after being off for an extended period.
According to one form of the present invention, a fuel supply apparatus includes a fuel pump, a housing, and a filter element disposed in the housing and having an upstream side communicating with a discharge port of the fuel pump. A fuel supply
Tsutsui Seiji
Wakabayashi Hideya
Yoshioka Hiroshi
Mitsubishi Denki & Kabushiki Kaisha
Moulis Thomas N.
Sughrue & Mion, PLLC
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