Internal-combustion engines – Charge forming device – With fuel pump
Reexamination Certificate
2003-01-30
2003-11-04
Moulis, Thomas N. (Department: 3747)
Internal-combustion engines
Charge forming device
With fuel pump
C123S514000
Reexamination Certificate
active
06640787
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electronically controlled fuel injection device which is used to supply fuel to an internal combustion engine (hereafter referred to simply as an engine, and more particularly to an electronically controlled fuel injection device used in engines that are mounted in two-wheeled vehicles and the like.
BACKGROUND ART
Conventionally, electronically controlled fuel injection devices which control the fuel injection timing and amount of injection, i.e., injection period or the like, by means of an electronic circuit have been employed in four-cycle gasoline engines mounted in automobiles and the like, and especially in multi-cylinder gasoline engines with 4, 6 or 8 cylinders which have a relatively large total displacement of approximately 1000 cc to 4000 cc, from the standpoint of improving fuel economy in response to exhaust gas regulations, or from the standpoint of improving the operating characteristics.
For example,
FIG. 23
shows a known electronically controlled fuel injection device. This device is a port injection type device which injects fuel toward an intake port of an engine
1
by means of an electromagnetic valve type injector
3
which is attached at an inclination toward the downstream side with respect to an intake passage inside the intake manifold
2
of the engine
1
. In this port injection type electronically controlled fuel injection device, as is shown in
FIG. 23
, fuel (gasoline) inside a fuel tank
4
is fed out under pressure by an in-tank fuel pump
5
accommodated inside the fuel tank
4
, e.g., a centrifugal flow type fuel pump. This fuel is supplied to the injector
3
via a highly pressure-resistant fuel feed pipe
7
and a delivery pipe (not shown) after passing through a high-pressure filter
6
at an intermediate point.
Furthermore, the fuel conducted by the fuel feed pipe
7
is also fed into a fuel pressure regulator
8
, and the excess fuel (i.e., the fuel not injected from the injector
3
) is returned to the fuel tank
4
via a fuel return pipe
9
. As a result, the pressure of the fuel upstream of the injector
3
(i.e., the fuel pressure) is maintained at a specified high pressure value. Thus, since the pressure of the fuel is maintained at a high pressure, the generation of vapor in the case of high temperatures or the like is suppressed; furthermore, the fuel that is injected from the injector
3
can be finely atomized.
Furthermore, in order to detect the conditions of the engine
1
in an appropriate manner, this electronically controlled fuel injection device is equipped with an engine rotational speed sensor
10
, a water temperature sensor
11
, an O
2
sensor
12
, an intake pressure sensor
13
, a throttle sensor
14
, and air flow rate sensor
15
, an intake temperature sensor
16
and the like. On the basis of operating information concerning the engine
1
that is detected by these sensors, a control unit (ECU)
17
that is equipped with an electronic circuit calculates the current optimal fuel injection amount, i.e., the fuel injection time and fuel injection timing, and transmits this information to the injector
3
. As a result, the injection time and injection timing of the fuel from the injector
3
are optimally controlled in accordance with the operating conditions of the engine
1
.
Meanwhile, in the case of engines with a relatively small displacement that are mounted in two-wheeled vehicles or comparable vehicles, or in other engine-driven devices, e.g., engines with a displacement of approximately 50 cc to 250 cc per cylinder, fuel injection devices using carburetors or the like that control the amount of fuel injection by means of pressure have been employed in the past, one reason being that exhaust gas regulations and the like were not too strict for such engines.
However, as a recent step in the prevention of global warming and environmental protection, fine control of combustion for the purpose of reducing emissions of carbon dioxide, hydrocarbons and the like by reducing fuel consumption has become necessary even in such engines with a small displacement.
When an attempt is made to achieve optimal fuel injection in the same manner as in large-displacement automobile engines by using systems similar to existing electronically controlled fuel injection devices instead of conventional carburetors, the following problems arise.
First of all, in the case of an electronically controlled fuel injection device using a conventional fuel pump
5
and injector
3
, either time or area is used as a control parameter in controlling the amount of fuel injection and the like. Accordingly, the flexibility of control, i.e., the control range, is narrow, so that such devices are undesirable in the case of engines mounted in two-wheeled vehicles and the like, in which it is necessary to perform optimal control of the combustion while giving serious consideration to the operating performance from the standpoint of the application involved.
Secondly, conventional fuel pumps
5
are centrifugal flow type fuel pumps, and have a relatively large and complicated structure equipped with pump parts, motor parts and the like. Furthermore, an in-tank installation system in which the fuel pump is disposed inside the fuel tank
4
is generally employed; as a result, for example, it is difficult to fit such a fuel pump in a two-wheeled vehicle engine in which there are restrictions on the size and shape of the fuel tank.
Third, since the fuel feed pipe
7
extending from the fuel pump
5
to the injector
3
is filled with high-pressure fuel, such a system is undesirable from the standpoint of safety in the case of engines mounted in two-wheeled vehicles, in which accidental spills (i.e., accidents in which two-wheeled vehicles are laid down) and the like must be taken into consideration.
Fourth, in the case of conventional systems which supply fuel at a high pressure, the electric power consumption of the fuel pump
5
itself is large; furthermore, it is necessary to circulate fuel at a high flow rate via the fuel pressure regulator
8
. As a result, the overall electric power consumption is increased even further. Accordingly, such systems are undesirable for engines mounted in two-wheeled vehicles and the like, in which there is a need to reduce the electric power consumption.
Fifth, in the case of conventional systems which supply fuel at a high pressure, a high pressure resistance is required, so that such systems are generally expensive, including the cost of the materials of the constituent parts, the cost of high quality control during manufacture and the like. Accordingly, such systems are undesirable for engines mounted in two-wheeled vehicles, in which there is a demand for cost reduction.
The present invention was devised in light of the above-mentioned problems encountered in the prior art. It is an object of the present invention to provide an electronically controlled fuel injection device which makes it possible to achieve an optimal combustion state by means of precise control such that exhaust gas countermeasures are also performed while maintaining the operating performance in a small-displacement engine, e.g., an engine mounted in a two-wheeled vehicle or the like, and at the same time achieving a reduction in electric power consumption, a reduction in cost, a reduction in size and a reduction in the installation space required.
SUMMARY OF THE INVENTION
The first electronically controlled fuel injection device of the present invention is an electronically controlled fuel injection device which injects fuel into the intake passage of an engine, comprising a volume type (i.e., positive displacement) electromagnetically driven pump which uses electromagnetic force as a driving source, and which pressure-feeds fuel conducted from the fuel tank, an inlet orifice nozzle which has an orifice part that allows the passage of the fuel that is pressure-fed by this electromagnetically driven pump, an outlet orifice nozzle which has an orifice part that allows the passage of fuel s
Ehara Ryoji
Hashimoto Shogo
Mizui Hiroshi
Nichogi Tadashi
Takahashi Junichiro
Mikuni Corporation
Moulis Thomas N.
Wenderoth , Lind & Ponack, L.L.P.
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