Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
2002-08-02
2004-10-19
Miller, Carl S. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C123S456000
Reexamination Certificate
active
06805106
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a fuel-injection system for an automotive fuel-injected engine that fuel is injected into a combustion chamber via a fuel injector.
BACKGROUND ART
Generally, there are two types of electronic fuel-injection systems mounted on automotive vehicles, namely a so-called non-return system (see
FIG. 7
) and a so-called full-return system (see FIG.
8
). The non-return system shown in
FIG. 7
includes at least a fuel tank
1
, a fuel pump
3
, a fuel supply line
5
, fuel injectors
10
, an upstream pressure regulator
11
, and a fuel return line
12
. For instance, in a four-wheeled vehicle, tank
1
is usually mounted at the rear of the vehicle and has a fuel storage capacity of several tens of liters. Tank
1
is constructed as a sealed fuel tank. Pump
3
is provided in the interior or exterior space of tank
1
. Pump
3
is generally comprised of an electric fuel pump that is driven by an electric motor. Pump
3
is provided for inducting fuel
2
stored in tank
1
and for discharging pressurized fuel toward the upstream side of supply line
5
. The non-return system of
FIG. 7
is exemplified in a four-cylinder fuel-injected engine that has four fuel injectors
10
on each cylinder of an internal combustion engine
4
to deliver fuel
2
to each of four combustion chambers. Supply line
5
is provided for supplying fuel
2
to the respective injectors. Supply line
5
includes a feed pipe
6
extending from the front end of the vehicle to the rear end, fuel distributor pipes
7
and
8
, and a connecting pipe
9
intercommunicating two distributor pipes
7
and
8
. Feed pipe
6
is connected to the discharge outlet of pump
3
to supply fuel
2
to the respective fuel distributor pipes
7
and
8
. Distributor pipes
7
and
8
are made of a metal pipe material having a substantially cylindrical shape and located near the combustion chambers so that distributor pipes
7
and
8
extend straight along the respective sidewall surfaces of engine
4
. In the non-return system of
FIG. 7
, the pressurized fuel from pump
3
is discharged into the upstream side of feed pipe
6
and delivered into upstream pressure regulator
11
that prevents excessive pressure from developing and regulates the output pressure from upstream pressure regulator
11
to a predetermined pressure, for example, a pressure level ranging from 250 to 350 kPa. First, the fuel regulated by upstream pressure regulator
11
is supplied into the first distributor pipe
7
of distributor pipes
7
and
8
. Then, the regulated fuel is further delivered via connecting pipe
9
to the second distributor pipe
8
. The downstream end
8
A of second distributor pipe
8
is formed as a dead end of supply line
5
. As shown in
FIG. 7
, a first group of injectors
10
,
10
are integrally connected to first distributor pipe
7
, whereas a second group of injectors
10
,
10
are integrally connected to second distributor pipe
8
. In the system shown in
FIG. 7
, the four fuel injectors and distributor pipes
7
and
8
construct a so-called “gallery-type” fuel-pipe integrated fuel injection unit. An electromagnetic actuator (electromagnetic solenoid) is built within the injector body and is responsive to a control signal from an electronic engine control unit (ECU) to control both opening and closing of each fuel injector
10
. When the actuator is energized and thus the injector valve of each fuel injector
10
opens, the fuel within distributor pipes
7
and
8
is sprayed or injected into the combustion chamber. The amount of fuel injected is controlled by a fuel-injection signal from the ECU. Generally, a pulsewidth modulated control signal or a duty-cycle modulated pulsewidth signal is used as the fuel-injection signal. Upstream pressure regulator
11
is disposed in a middle of feed pipe
6
of supply line
5
and includes an inflow conduit portion
11
A, an outflow conduit portion
11
B, and a return conduit portion
11
C. Return conduit portion
11
C is connected to return line
12
that is connected to tank
1
. Upstream pressure regulator
11
uses intake manifold pressure (manifold vacuum) as a control pressure. Surplus fuel is returned through return line
12
to tank
1
, after pressure-regulating action of upstream pressure regulator
11
. As clearly seen in
FIG. 7
, an installation position of upstream pressure regulator
11
is spaced apart from engine
4
. For instance, upstream pressure regulator
11
is mounted on a floor panel corresponding to the bottom portion of the engine room in order to suppress heat from being transferred from engine
4
to return line
12
. Although it is not shown in
FIG. 7
, a fuel filter is disposed in feed pipe
6
and located between the discharge port of pump
3
and the pressure-regulator inflow conduit portion
11
A to remove any impurities from the fuel flowing through feed pipe
6
. According to the non-return system shown in
FIG. 7
, when pump
3
is activated and thus fuel
2
stored in tank
1
is discharged into feed pipe
6
of supply line
5
, a portion of fuel discharged from pump
3
flows from the pressure-regulator inflow conduit portion
11
A to the pressure-regulator outflow conduit portion
11
B (see the fuel flow indicated by the arrow A) and is delivered into distributor pipes
7
and
8
located downstream of the pressure-regulator outflow conduit portion
11
B. In this manner, a portion of fuel flowing through distributor pipes
7
and
8
and having the fuel-injection pressure controlled by upstream pressure regulator
11
can be injected through each fuel injector
10
into the combustion chamber. As indicated by the arrow B in
FIG. 7
, as a result of fuel-pressure regulating action of upstream pressure regulator
11
, as the surplus fuel, most of the fuel discharged from pump
3
returns through the pressure-regulator return conduit portion
11
C via return line
12
to tank
1
, without flowing through distributor pipes
7
and
8
.
On the other hand, in the full-return system shown in
FIG. 8
, one end of a fuel return line
13
is connected to the downstream end
8
A of supply line
5
, whereas the other end of return line
13
is connected to tank
1
. A downstream pressure regulator
14
is disposed in a middle of return line
13
. As seen in
FIG. 8
, downstream pressure regulator
14
includes an inflow conduit portion
14
A that is connected to the downstream end
8
A of second distributor pipe
8
via the upstream portion of return line
13
, and a return conduit portion
14
B that is connected to tank
1
via the downstream portion of return line
13
. Downstream pressure regulator
14
functions to return the surplus fuel through the pressure-regulator return conduit portion
14
B to tank
1
(see the return flow indicated by the arrow C in FIG.
8
), while regulating the fuel passing through distributor pipes
7
and
8
and returning into return line
13
to the predetermined pressure level (250-350 kPa). According to the full-return system shown in
FIG. 8
, when pump
3
is activated and thus fuel
2
stored in tank
1
is discharged into feed pipe
6
of supply line
5
, all the fuel discharged from pump
3
is delivered into first distributor pipe
7
(see the fuel flow indicated by the arrow A in FIG.
8
). In this manner, a portion of fuel flowing through distributor pipes
7
and
8
and having the fuel-injection pressure controlled by downstream pressure regulator
14
can be injected through each fuel injector
10
into the combustion chamber. As indicated by the arrow C in
FIG. 8
, as a result of fuel-pressure regulating action of downstream pressure regulator
14
, as the surplus fuel, most of the fuel discharged from pump
3
passes through distributor pipes
7
and
8
and thereafter consecutively returns via the pressure-regulator return conduit portion
14
B and return line
13
to tank
1
. In case of the full-return system of
FIG. 8
, the surplus fuel has to pass through distributor pipes
7
and
8
. Heat is undesirably transferred from engine
4
to the surpl
Kumagai Masato
Mori Kazuyoshi
Yamada Hiroshi
Miller Carl S.
Unisia Jecs Corporation
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