Information
-
Patent Grant
-
6792923
-
Patent Number
6,792,923
-
Date Filed
Wednesday, September 10, 200321 years ago
-
Date Issued
Tuesday, September 21, 200419 years ago
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Inventors
-
Original Assignees
-
Examiners
Agents
-
CPC
-
US Classifications
Field of Search
US
- 123 494
- 123 514
- 123 509
- 123 516
- 137 558
- 137 565
- 137 592
- 137 590
- 073 317
- 073 305
- 073 304
- 073 307
- 073 306
- 073 314
- 073 303
- 073 313
- 073 302
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International Classifications
-
Abstract
A fuel supply system for a vehicle, the fuel supply system being comprised of a fuel tank, a fuel pump installed in the fuel tank, a fuel level detection unit which is comprised of a float and a sensor member which detects a vertical displacement of the float, and a pressing member which presses with elasticity the sensor member against the inside bottom of the fuel tank.
Description
BACKGROUND OF THE INVENTION
The present invention relates to a fuel supply system for a vehicle, in particular, it relates to a fuel supply system for a vehicle which can be favorably employed to supply fuel inside a fuel tank to a vehicle engine.
Generally, a fuel supply system which supplies fuel to an engine or similar device comprises a pump unit which delivers fuel to the engine, and a fuel level detection device which detects a level of fuel remaining in a fuel tank, both the pump unit and the fuel level detection device being disposed inside the fuel tank. The pump unit comprises a fuel pump installed on an upper surface of the fuel tank to suck fuel and deliver the fuel, and a chamber which is cylindrical and closed at the bottom to maintain an amount of fuel around an intake opening of the fuel pump.
The fuel level detection device is mostly comprised of a float which floats on the surface of fuel stored inside the fuel tank, and thus has an upward or downward displacement corresponding to a rise or fall of the surface of the fuel, and a sensor member which is installed on the pump unit to detect a vertical position or height of the surface of the fuel, i.e., a level of the fuel, by detecting a vertical position or height of the float.
Japanese Patent Provisional Application (Helsei) 10-47185 discloses a fuel supply system for supplying fuel that has been sucked by the fuel pump to fuel injectors of an engine by driving the fuel pump of the pump unit.
The float, which floats on the surface of the fuel held in the fuel tank, has a vertical displacement according to a change in height of the surface of the fuel, and the amount of fuel remaining in the fuel tank is detected by detecting the position of the float with the sensor member of the fuel level detection device.
SUMMARY OF THE INVENTION
However, in a fuel supply system according to the above related art, the sensor member of the fuel level detection device is installed on the pump unit, and the pump unit is installed on the upper surface of the fuel tank.
Depending on manufacturing tolerances during assembly, the distance or height from the inside bottom to the inside top of the fuel tank differs slightly with individual fuel tanks. Also, a fuel tank expands or contracts depending on internal pressure of the fuel tank, and the vertical distance from the inside bottom to the inside top of the fuel tank changes.
There is a recent trend to form fuel tanks using a flexible, light-weight material such as synthetic resin in striving for lightness of the entire vehicle, and a fuel tank designed using flexible material deforms depending on a range of factors including change in volume and therefore weight of fuel being held in the tank, change in pressure within the fuel tank, change in temperature around the exterior of the fuel tank, or vibration or shock while the vehicle is traveling.
When a fuel tank deforms in such a way, the surface of the fuel inside the fuel tank rises or falls correspondingly with no change in the actual amount of fuel remaining. Thus, a fuel level detection device according to the related art, which is installed on an upper surface of a fuel tank to detect the amount of fuel remaining by detecting the height or level of the surface of the fuel under such conditions, gives a detection result that is not an accurate indication of the amount of fuel remaining. The problem that arises, then, is how to stabilize a remaining amount of fuel relative to a fuel level detection device to obtain an accurate detection result.
It is therefore an object of the present invention to provide a fuel supply system which is capable of stabilizing fuel inside a fuel tank relative to a fuel level detection device so that the level of remaining fuel can be more accurately determined.
An aspect of the present invention resides in a fuel supply system for a vehicle, the fuel supply system comprising a fuel tank, a pump unit which is installed on a top of the fuel tank, the pump unit sucking fuel from the fuel tank and delivering the fuel to an engine, a fuel level detection device disposed in the fuel tank, the fuel level detection device comprising a float which floats on the fuel in the fuel tank, and a sensor member which is disposed between an inside bottom of the fuel tank and the pump unit, the sensor member detecting a displacement of the float, and a pressing member which is disposed between the pump unit and the sensor member, the pressing member tending to expand and press against the sensor member, the sensor member being pressed against the inside bottom of the fuel tank.
Another aspect of the present invention resides in a fuel supply system for a vehicle which comprises an engine, the fuel supply system comprising a fuel tank, pump means for sucking fuel from the fuel tank and delivering the fuel to the engine, the pump means comprising containing means for maintaining an amount of fuel inside the pump means, the containing means being disposed inside the fuel tank, a float which floats on the surface of fuel in the fuel tank, the float having an upward or downward displacement which corresponds to a respective rise or fall in the surface of the fuel, sensor means for detecting the displacement of the float, the sensor means being disposed on a bottom of the fuel tank, and pressing means for pressing the sensor member against the bottom of the fuel tank with elasticity, the pressing means extending from the containing means.
A further aspect of the present invention resides in a fuel supply system for a vehicle comprising an engine and a fuel tank, the fuel supply system comprising a pump unit which is disposed on a top of the fuel tank, the pump unit comprising a chamber suspended inside the fuel tank, a sensor member which is disposed on an inside bottom of the fuel tank, a float which has a displacement corresponding to a change in a level of the surface of the fuel, the displacement being detected by the sensor member, and elastic pressing means for pressing against the sensor member with elasticity, the elastic pressing means being disposed between a top of the sensor member and the chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is a cross-sectional view of a first embodiment of a fuel supply system according to the present invention.
FIG. 2
is an enlarged cross-sectional view of a chamber, suction pump, and other components of the fuel supply system shown in
FIG. 1
taken along the line II—II.
FIG. 3
is a cross-sectional view of a second embodiment of the fuel supply system according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to
FIGS. 1 and 2
, there is discussed a first embodiment of a fuel supply system in accordance with the present invention.
A fuel tank
1
for holding fuel is mounted in a vehicle as shown in
FIG. 1
, fuel tank
1
being designed substantially in a box shape and is made from a material such as metal or resin. Fuel tank
1
comprises a bottom portion
1
A and a top portion
1
B, top portion
1
B defining an installation opening
1
C on which a cover
2
is installed.
Cover
2
acts to cover and close installation opening
1
C. Cover
2
comprises a flat portion
2
A which rests on the top of top portion
1
B to form a substantially continuing surface with top portion
1
B, and a chamber installation portion
2
B which is cylindrical and formed on an underside of flat portion
2
A so as to project through installation opening
1
C and into fuel tank
1
.
A pump unit
3
acts as a pump installed on top portion
1
B of fuel tank
1
by means of cover
2
. Pump unit
3
serves to suck fuel from inside fuel tank
1
and deliver the sucked fuel to an engine (not shown). Pump unit
3
is largely comprised of a chamber
4
, a fuel pump
5
, and a suction pump
10
.
Chamber
4
is disposed inside fuel tank
1
in a suspended fashion from top portion
1
B. As shown in
FIGS. 1 and 2
, chamber
4
is formed as a cylinder with a closed bottom, comprising a cylinder portion
4
A which is installed on chamber installation portion
2
b
of cover
2
and acts as an enclosing side wall of chamber
4
, and a base portion
4
B which closes the bottom of cylinder portion
4
A and acts as a bottom of chamber
4
. Chamber
4
serves as a constant reservoir for a portion of the fuel inside fuel tank
1
so that an amount of fuel is maintained inside pump unit
3
around an intake opening
5
A of fuel pump
5
. On the outside bottom of base portion
4
B, which comes within proximity of bottom portion
1
A of fuel tank
1
, a spring attachment projection
4
C is disposed to project toward bottom portion
1
A of fuel tank
1
. A coiled spring
16
is attached to spring attachment projection
4
C.
Fuel pump
5
is disposed with a vertical orientation within chamber
4
such that one end faces flat portion
2
A of cover
2
and another end faces base portion
4
B. Fuel pump
5
sucks fuel from inside chamber
4
and delivers the fuel to the fuel injectors (not shown) of an engine. Fuel pump
5
includes a motor member (not shown) which has a rotor which rotates relative to a stator when electrically energized by an external source, a pump member (not shown) which is rotatingly driven by the motor member to perform sucking and delivering of fuel, intake opening
5
A through which fuel inside chamber
4
is sucked, and a delivery opening
5
B through which the sucked fuel is delivered to a supply pipe
7
, described hereinafter. An internal intake filter
6
is attached to intake opening
5
A to prevent foreign particles from entering fuel pump
5
as fuel is sucked from inside chamber
4
, through intake opening
5
A, and into fuel pump
5
.
Supply pipe
7
carries fuel from inside tank
1
to outside tank
1
. An inflow end of supply pipe
7
is connected to delivery opening
5
B of fuel pump
5
. Supply pipe
7
comprises a connecting branch
7
A which extends laterally, and a delivery branch
7
B which extends upward from an outflow end of connecting branch
7
A. The outflow end of delivery branch
7
B projects through flat portion
2
A of cover
2
to outside of fuel tank
1
, and is connected to fuel injectors via a fuel conduit.
An inflow end of a suction pump pipe
8
is connected to connecting branch
7
A of supply pipe
7
, and an outflow end of suction pump pipe
8
is connected to suction pump
10
. A suction pump pipe
8
supplies a portion of fuel which is being delivered by fuel pump
5
to suction pump
10
, described later. A narrow portion
9
is disposed within suction pump pipe
8
at a position approximately halfway thereof to separate fuel being delivered by fuel pump
5
into a portion which flows to suction pump
10
and a portion which flows to an engine.
Suction pump
10
is disposed on an inside bottom of chamber
4
, and comprises, for example, a jet pump, which utilizes a portion of fuel being delivered from fuel pump
5
to cause fuel outside chamber
4
to flow into chamber
4
.
As shown in
FIGS. 1 and 2
, suction pump
10
comprises a nozzle portion
10
A connected to an outflow end of suction pump pipe
8
, a pump case
10
B formed as a cylinder to enclose nozzle portion
10
A, an intake pipe
10
C which extends from pump case
10
B and projects outside of chamber
4
, and an ejection opening
10
D disposed on pump case
10
B to eject fuel flowing out from nozzle portion
10
A together with fuel sucked from intake pipe
10
C together. An external intake filter
11
is attached to an end of intake pipe
10
C projecting outside of chamber
4
to prevent foreign particles from entering suction pump
10
.
A fuel level detection device
12
is disposed inside fuel tank
1
as a fuel level detection means to detect a level of fuel remaining inside fuel tank
1
. Fuel level detection device
12
comprises a float
13
, an arm
14
connected to float
13
, and a sensor member
15
to which arm
14
is swingably connected. Float
13
is buoyant and floats on the surface of fuel inside tank
1
, and is vertically displaced depending on the level of the surface of the fuel, that is, float
13
moves upward or downward with a respective rise or fall in the surface of fuel in fuel tank
1
. Sensor member
1
s is disposed on an inside bottom of fuel tank
1
near a lower end of chamber
4
such that sensor member
15
is disposed under chamber
4
.
Since one end of arm
14
is connected to float
13
which moves upward and downward relative the inside bottom of fuel tank
1
, and the other end of arm
14
is connected to sensor member
15
which does not move relative to the inside bottom of fuel tank
1
, an angle of arm
14
depends on the displacement or vertical position of float
13
. Sensor
15
contains an internal potentiometer or similar device, and detects the angle of arm
14
based on a detected change in electrical resistance. Sensor member
15
is pressed against bottom portion
1
A of fuel tank
1
by coiled spring
16
, described later. Further, a spring attachment projection
15
A is disposed on a top surface of sensor member
15
so as to project upward in opposition to spring attachment projection
4
C of chamber
4
.
By sensor member
15
being disposed on bottom portion
1
A of fuel tank
1
, displacement of float
13
is easily ascertained by detecting an angle of arm
14
using bottom portion
1
A as a reference point. This enables an accurate detection of the amount of remaining fuel in tank
1
by fuel level detection device
12
. This will be explained in more detail later.
Coiled spring
16
extends from chamber
4
as a pressing means between chamber
4
of pump unit
3
and sensor member
15
of fuel level detection device
12
such that sensor member
15
is disposed between coiled spring
16
and bottom portion
1
A of fuel tank
1
. Coiled spring
16
tends to expand and push against sensor member
15
, therefore, sensor member
15
is pressed against bottom portion
1
A of fuel tank
1
with elasticity. That is, coiled spring
16
presses sensor member
15
against bottom portion
1
A of fuel tank
1
by the spring force of coiled spring
16
. One end of coiled spring
16
is fitted around spring attachment projection
4
C disposed on base portion
4
B of chamber
4
, and another end is fitted around spring attachment projection
15
A disposed on a top surface of sensor member
15
.
The level of the surface of fuel inside fuel tank
1
can change although the amount of fuel actually present does not change. This is due to the physical dimensions of fuel tank
1
changing, and is attributable to various influences. As an example, a vertical distance H from bottom portion
1
A to top portion
1
B inside fuel tank
1
may differ depending on manufacturing tolerances during assembly. Vertical distance H may also vary when fuel tank
1
expands or contracts as a result of changes in internal pressure.
Fuel tank
1
, being made of a resin material, may also deform due to a change in amount and therefore weight of fuel being held, a change in internal pressure of fuel tank
1
, a change in temperature outside fuel tank
1
, or due to vibration or shock which may occur while the vehicle is traveling. Under such conditions, float
13
rises or falls together with the surface of fuel in fuel tank
1
, therefore having a vertical displacement.
To counter these effects, coiled spring
16
is formed to be expandable in such instances to a necessary length, and is therefore able to constantly press sensor member
15
to bottom portion
1
A of fuel tank
1
, including instances where fuel tank
1
deforms and vertical distance H reaches a maximum value.
Operation of the fuel supply system will now be explained. First, by driving fuel pump
5
, fuel pump
5
sucks fuel from inside chamber
4
through intake opening
5
A, and delivers the fuel through delivery opening
5
B to connecting branch
7
A of supply pipe
7
. Next, fuel flows both into suction pump pipe
8
and into delivery branch
7
B of supply pipe
7
. The portion of fuel flowing into delivery branch
7
B is delivered to fuel injectors via a fuel conduit, and eventually injected from the fuel injectors into the cylinders of an engine.
The portion of fuel flowing into suction pump pipe
8
passes through narrow portion
9
and flows into suction pump
10
to drive suction pump
10
. Thus, fuel inside fuel tank
1
is drawn by suction pump
10
into chamber
4
.
Detection of a remaining amount of fuel being held in fuel tank
1
using fuel level detection device
12
will be explained.
The surface of fuel held in fuel tank
1
rises or falls and is therefore vertically displaced when, for example, fuel is supplied to or consumed from fuel tank
1
. As a result, float
13
, which floats on the surface of the fuel, also rises or falls with the rise or fall of the surface of the fuel, and an angle of arm
14
with respect to sensor member
15
changes accompanying upward or downward movement of float
13
. In this way, sensor member
15
is able to detect a height or vertical position of float
13
and determine the amount of fuel remaining based on the angle of arm
14
.
According to the first embodiment of the present invention, coiled spring
16
is disposed between chamber
4
of pump unit
3
and sensor member
15
of fuel level detection device
12
, so that sensor member
15
is pressed with elasticity against bottom portion
1
A of fuel tank
1
by coiled spring
16
. Thus, sensor member
15
of fuel level detection device
12
is constantly maintained on bottom portion
1
A of fuel tank
1
. It is then possible for sensor member
15
to use bottom portion
1
A as a reference point when detecting vertical displacement of float
13
.
As a result, even in an instance where fuel tank
1
deforms and vertical distance H inside fuel tank
1
changes, fuel level detection device
12
rises or falls similar to the surface of fuel inside fuel tank
1
. Fuel level detection device
12
is therefore able to detect a remaining amount of fuel with disregard for vertical distance H.
Moreover, sensor member
15
can be simply emplaced using base portion
4
B of chamber
4
, and also, when installing pump unit
3
in fuel tank
1
, fuel level detection device
12
can also be installed at the same time, so the amount of assembly time required can also be reduced.
Further, when changing the layout inside fuel tank
1
, that is, the installation position of fuel level detection device
12
, and even when installing in another fuel tank of differing shape, any change in vertical distance H can be compensated for owing to the elastic property of coiled spring
16
, so fuel level detection device
12
can be simply adapted to the fuel tank.
A second embodiment of the present invention will now be explained referring to
FIG. 3. A
feature of the second embodiment lies in a sensor member of a fuel level detection means being disposed to the side of a chamber inside a fuel tank, the sensor member being pressed against an inside bottom of the fuel tank by a helical torsion spring. Elements which are common to both the second embodiment and the first embodiment make use of the same reference numerals, and explanation thereof is abbreviated.
A fuel level detection device
21
comprises a float
22
, an arm
23
, and a sensor member
24
. Fuel level detection device
21
functions as a fuel level detection means in the second embodiment to detect a level of remaining fuel being held in fuel tank
1
in a substantially similar manner as fuel level detection device
12
of the first embodiment. However, fuel level detection device
21
according to the second embodiment differs from fuel level detection device
12
of the first embodiment in that sensor member
24
is disposed to the side of chamber
4
between bottom portion
1
A of fuel tank
1
and pump unit
3
. That is, sensor member
24
is disposed outside an area which is directly under chamber
4
.
A helical torsion spring
25
extends from chamber
4
as a pressing means disposed between chamber
4
and sensor member
24
of fuel level detection device
21
. Helical torsion spring
25
tends to expand and push against sensor member
24
, therefore, sensor member
24
is pressed against bottom portion
1
A of fuel tank
1
with elasticity. That is, sensor member
24
is pressed against bottom portion
1
A of fuel tank
1
by spring force of helical torsion spring
25
. One end of helical torsion spring
25
is attached to cylinder portion
4
A of chamber
4
such that helical torsion spring
25
is attached to a side of chamber
4
, and another end thereof is attached to a top surface of sensor member
24
. Helical torsion spring
25
is capable of constantly pressing sensor member
24
against bottom portion
1
A, even in an instance where fuel tank
1
deforms and vertical distance H increases to a maximum value.
Also, with the second embodiment composed in this manner, it is possible to gain effects similar to those of the first embodiment. Particularly, the second embodiment is more widely adaptable to changes in layout or to other fuel tanks, since sensor member
24
of fuel level detection device
21
is disposed to the side of chamber
4
, so that an amount of space available for sensor member
24
directly underneath chamber
4
does not have to be taken into account.
This application is based on a prior Japanese Patent Application No. 2002-381139 filed on Dec. 27, 2002. The entire contents of these Japanese Patent Applications No. 2002-381139 are hereby incorporated by reference.
Although the invention has been described above by reference to certain embodiments of the invention, the invention is not limited to the embodiments described above. Modifications and variations of the embodiments described above will occur to those skilled in the art in light of the above teachings. For example, other pressing means, such as a rubber spring or a leaf spring may be employed. Also, for example, fuel pump
5
may be installed on a vertically descending bracket which may be attached to cover
2
with pressing means being disposed between fuel pump
5
and sensor member
15
of fuel level detection device
12
. The scope of the invention is defined with reference to the following claims.
Claims
- 1. A fuel supply system for a vehicle, the fuel supply system comprising:a fuel tank; a pump unit which is installed on a top of the fuel tank, the pump unit sucking fuel from the fuel tank and delivering the fuel to an engine; a fuel level detection device disposed in the fuel tank, the fuel level detection device comprising a float which floats on the fuel in the fuel tank, and a sensor member which is disposed between an inside bottom of the fuel tank and the pump unit, the sensor member detecting a displacement of the float; and a pressing member which is disposed between the pump unit and the sensor member, the pressing member pressing against the sensor member, the sensor member being pressed against the inside bottom of the fuel tank.
- 2. The fuel supply system as claimed in claim 1, wherein the pump unit comprises a fuel pump which sucks fuel from the fuel tank and delivers the sucked fuel, and a chamber which is disposed inside the fuel tank, the chamber being cylindrical and having a closed bottom to maintain fuel around an intake opening of the fuel pump.
- 3. The fuel supply system as claimed in claim 1, wherein the pressing member is connected to the sensor member and a bottom of the chamber.
- 4. The fuel supply system as claimed in claim 3, wherein the sensor member is disposed under the chamber.
- 5. The fuel supply system as claimed in claim 4, wherein the pressing member comprises a coiled spring, one end of the coiled spring being connected to a bottom of the chamber and another end thereof being connected to the sensor member.
- 6. The fuel supply system as claimed in claim 5, wherein the chamber comprises a first attachment projection on the bottom thereof, one end of the coiled spring being connected to the first attachment projection.
- 7. The fuel supply system as claimed in claim 6, wherein the sensor member comprises a second attachment projection on a top thereof, the other end of the coiled spring being connected to the second attachment projection.
- 8. The fuel supply system as claimed in claim 1, wherein the pressing member is connected to the sensor member and a side of the chamber.
- 9. The fuel supply system as claimed in claim 8, wherein the sensor member is disposed outside an area which is directly under the chamber.
- 10. The fuel supply system as claimed in claim 8, wherein the pressing member comprises a helical torsion spring, one end of the helical torsion spring being connected to a side of the chamber and another end thereof being connected to the sensor member.
- 11. The fuel supply system as claimed in claim 1, wherein the pressing member comprises a spring, one end of the spring being connected to the chamber and another end of the spring being connected to the sensor member.
- 12. The fuel supply system as claimed in claim 1, wherein the pressing member is disposed between the chamber and the sensor member.
- 13. The fuel supply system as claimed in claim 1, wherein the sensor member comprises an arm, one end of the arm being swingably connected to the sensor member and the other end of the arm being connected to the float.
- 14. A fuel supply system for a vehicle which comprises an engine, the fuel supply system comprising:a fuel tank; pump means for sucking fuel from the fuel tank and delivering the fuel to the engine, the pump means comprising containing means for maintaining an amount of fuel inside the pump means, the containing means being disposed inside the fuel tank; a float which floats on the surface of fuel in the fuel tank, the float having an upward or downward displacement which corresponds to a respective rise or fall in the surface of the fuel; sensor means for detecting the displacement of the float, the sensor means being disposed on a bottom of the fuel tank; and pressing means for pressing the sensor member against the bottom of the fuel tank with elasticity, the pressing means extending from the containing means.
- 15. A fuel supply system for a vehicle comprising an engine and a fuel tank, the fuel supply system comprising:a pump unit which is disposed on a top of the fuel tank, the pump unit comprising a chamber suspended inside the fuel tank; a sensor member which is disposed on an inside bottom of the fuel tank; a float which has a displacement corresponding to a change in a level of the surface of the fuel, the displacement being detected by the sensor member; and elastic pressing means for pressing against the sensor member with elasticity, the elastic pressing means being disposed between a top of the sensor member and the chamber.
Priority Claims (1)
Number |
Date |
Country |
Kind |
2002-381139 |
Dec 2002 |
JP |
|
US Referenced Citations (11)
Foreign Referenced Citations (1)
Number |
Date |
Country |
10-47185 |
Feb 1998 |
JP |