Pipes and tubular conduits – Flexible – Distinct layers
Reexamination Certificate
2001-03-26
2003-06-10
Hook, James (Department: 3752)
Pipes and tubular conduits
Flexible
Distinct layers
C138S141000, C428S036910
Reexamination Certificate
active
06575199
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to fluid supply pipes for supplying a fluid, such as a liquid or gas. In particular, the present invention relates to fluid supply pipes in which the amount of electric charge that builds up in the fluid when the fluid passes through the fluid supply pipes can be maintained within a proper range.
BACKGROUND OF THE INVENTION
Fuel supply systems have been recently developed in which a fuel pump and a fuel filter are disposed within a fuel tank that is installed in a location some distance away from an internal combustion engine of a vehicle, in which fuel is drawn out of the fuel tank by the fuel pump and is supplied to the internal combustion engine through a fuel supply pipe.
FIG. 8
schematically shows a construction of an example of such a known fuel supply system. The fuel supply system shown in
FIG. 8
is of a type that controls the fuel pump such that the pressure of the fuel that is supplied to a fuel injection valve is maintained at a desired pressure.
As shown in
FIG. 8
, an inlet pipe
20
and an exhaust pipe
30
are connected to an internal combustion engine
10
, and an inlet valve
13
and an exhaust valve
14
are disposed in the engine
10
. Air is filtered through an air cleaner
21
and is supplied into inlet pipe
20
via a throttle valve
22
. Throttle valve
22
controls the air flow rate. Fuel is also supplied from a fuel injection valve
40
into inlet pipe
20
. The air and the fuel are mixed within inlet pipe
20
and are supplied into each cylinder through inlet valve
13
. Further, combustion gas within the cylinder is exhausted into exhaust pipe
30
through exhaust valve
14
.
Further, fuel pump
42
(which is typically constructed in modules that are integrally formed with a fuel filter) is disposed within a fuel tank
41
and serves to draw fuel out of fuel tank
41
. Fuel is supplied from fuel tank
41
to a fuel injection valve
40
for each cylinder through a fuel supply pipe
73
and a delivery pipe
45
.
Fuel supply pipe
73
includes a fixed fuel supply pipe
73
b
that is fixedly attached to the vehicle body and also includes connecting fuel supply pipes
73
a
,
73
c
, which connect fixed fuel supply pipe
73
b
to fuel pump
42
and delivery pipe
45
. Fixed fuel supply pipe
73
b
comprises a metal, such as a conductive stainless steel. Fixed fuel supply pipe
73
b
is normally attached to the vehicle body by an elastic insulating element, such as plastic, in order to protect the fuel supply pipe
73
b
from vibrations. Connecting fuel supply pipes
73
a
,
73
c
comprise rubber. The use of connecting fuel supply pipe
73
a
facilitates removal and attachment of fuel pump
42
. Further, connecting fuel supply pipes
73
a
,
73
c
, which comprise rubber, can absorb vibrations from the vehicle body and the engine
10
.
A control unit (ECU)
60
executes various instructions based on detected signals that are transmitted from a fuel pressure sensor for detecting the fuel pressure, an intake pressure sensor for detecting the intake air pressure, an intake air temperature sensor for detecting the intake air temperature, a water temperature sensor for detecting the cooling water temperature and a sensor for detecting the opening amount of the throttle valve. For example, control unit
60
executes instructions to control the opening amount of throttle valve
22
in order to control the amount of intake air, instructions to control the opening and closing of fuel injection valve
40
in order to supply fuel into the cylinder, and instructions to control fuel pump
42
in order to maintain the fuel pressure at a desired pressure.
However, connecting fuel supply pipes
73
a
,
73
c
, which are made of rubber, deteriorate with time and thus require maintenance, such as replacement. Therefore, instead of using a rubber fuel supply pipe, it may be considered to use a resin fuel supply pipe that is easy to make and does not require maintenance.
When fuel passes through a rubber or resin fuel supply pipe, the fuel flows against the fuel supply pipe. Because of friction, the fuel and the fuel supply pipe become electrically charged. When a resin fuel supply pipe is used, a larger amount of electric charge is built up by such friction. Connecting a ground wire to the fuel supply pipe can discharge electric charge built up on the fuel supply pipe. However, electric charge built up in the fuel cannot be readily discharged. Therefore, if, for example, fuel that has been charged by passing through connecting fuel supply pipe
73
a
shown in
FIG. 8
then passes through fixed fuel supply pipe
73
b
made of metal, fixed fuel supply pipe
73
b
is inductively charged. Electric charge inductively built up on fixed fuel supply pipe
73
b
is discharged to the vehicle body, the operator or the like. At this time, because fixed fuel supply pipe
73
b
has a low bulk resistivity, the electric charge may be rapidly discharged and a spark discharge may be generated. If spark discharge is generated on fixed fuel supply pipe
73
b
, fixed fuel supply pipe
73
b
may deteriorate, and operations by the operator may be disturbed.
DISCLOSURE OF THE INVENTION
It is, accordingly, an object of the present invention to maintain within a proper range the amount of electric charge that builds up in the fluid when the fluid passes through a fluid supply pipe.
Another object of the invention is to maintain within a proper range the amount of electric charge that builds up in the fluid when the fluid passes through the fluid supply pipe and also to maintain within a proper range the electric discharge energy that is generated when the electric charge built up on the fluid supply pipe is discharged.
In a preferred embodiment of the invention, the bulk resistivity of the fluid supply pipe is chosen to be 10
11
&OHgr;·cm or less. By using this fluid supply pipe, the amount of electric charge that builds up in the fluid when the fluid passes through the fluid supply pipe can be maintained within a proper range.
In another preferred embodiment of the invention, the bulk resistivity of the fluid supply pipe is chosen to be within the range from 10
7
to 10
11
&OHgr;·cm. By using this fluid supply pipe, the amount of electric charge that builds up on the fluid when the fluid passes through the fluid supply pipe can be maintained within a proper range. Also, the electric discharge energy that is generated when the electric charge built up on the fluid supply pipe is discharged can be maintained within a proper range.
In a still another preferred embodiment of the invention, the fluid supply pipe has at least two layers. The bulk resistivity of the innermost layer is chosen to be within the range from 10
7
to 10
11
&OHgr;·cm and the bulk resistivity of the outermost layer is chosen to be 10
12
&OHgr;·cm or more. By using this fluid supply pipe, even if the fluid supply pipe is multi-layered, the amount of electric charge that builds up in the fluid when the fluid passes through the fluid supply pipe can be maintained within a proper range. Additionally, the electric discharge energy that is generated when the electric charge built up on the fluid supply pipe is discharged can be maintained within a proper range.
Further, in the preferred embodiments of the invention, the fluid supply pipe is made of a resin.
The present invention will be more apparent from the following detailed description of the best modes for performing the invention.
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patent: 5469892 (1995-11-01), Noone et al.
patent: 5472746 (1995-12-01), Miyajima et al.
patent: 5524673 (1996-06-01), Noone et al.
patent: 5996642 (1999-12-01), Noone et al.
patent: 6170534 (2001-01-01), Noone et al.
patent: 6180197 (2001-01-01), Nie et al.
patent: 6257281 (2001-07-01), Nie et al.
patent: 6279615 (2001-08-01), Iio et al.
patent: 6321795 (2001-11-01), Noone et al.
Nagai Takashi
Nakao Yoichi
Tanabe Yuichi
Ueda Hironori
Aisan Kogyo Kabushiki Kaisha
Dennison, Schultz & Dougherty
Hook James
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