Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2000-02-23
2003-01-21
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S19800E
Reexamination Certificate
active
06508232
ABSTRACT:
PRIORITY INFORMATION
The present application is based upon and claims priority to Japanese Application No. Hei 11-044792, filed Feb. 23, 1999, the entire contents of which is hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a fuel injection system for an engine, and more particularly to a fuel injection system suitable for an outboard motor engine.
2. Description of Related Art
In the interest of improving engine performance and particularly fuel efficiency and exhaust emission control, many types of engines now employ a fuel injection system for supplying fuel to the engine. Generally, in this system, fuel is injected into an air induction device or directly into a combustion chamber by a fuel injector. This fuel injection has the advantages of permitting the amount of fuel delivered for each cycle of the engine to be adjusted. In addition, by utilizing the fuel injection system, it is possible to maintain the desired fuel air ratio under a wide variety of engine running condition.
An amount of the fuel injected by the fuel injector is usually controlled by an ECU (Engine Control Unit) in response to the engine running conditions. More specifically, the fuel is delivered to the fuel injector by a fuel pump under a certain fixed pressure and duration for injection per unit time, i.e., a duty ratio, is controlled by the ECU so that any required amount of fuel can be metered.
The fuel injector generally has a construction shown in FIG.
1
. This figure illustrates a cross-sectional view showing an exemplary fuel injector.
The fuel injector, designated generally by the reference numeral
30
, includes an injector body
32
. An opening
34
is pierced longitudinally through the body
32
. A magnet core
36
is fixedly positioned at one side of the opening
34
, while a plunger
38
is slidably supported within the opening
34
at the other side of the opening
34
. The plunger
38
is biased by a coil spring
40
toward an end of the opening
34
and has a valve
42
that is seated on a valve seat
44
when urged by the spring
40
. The plunger
38
and the valve
42
are unified to define a needle valve. The valve
42
, therefore, closes the opening
34
when seated on the valve seat
44
. The end of the opening
34
at the side where the valve
42
is disposed is narrowed to define an injection nozzle
46
. A solenoid or electromagnetic actuator
48
is formed in the injector body
32
and surrounds respective portions of the magnet core
36
and plunger
38
. Fuel is supplied into the opening
34
through an inlet portion
50
by a fuel pump and hence fills the opening
34
under a certain fixed pressure. A fuel filter
51
is provided at the inlet portion
50
.
When the solenoid
48
is activated by the ECU, the magnetic core
36
and plunger
38
are magnetized. The plunger
38
then slides toward the magnetic core
36
against the biasing force of the coil spring
40
. The valve
42
is parted from the valve seat
44
accordingly. Because the fuel fills the opening
34
under the certain pressure, it is sprayed from the nozzle
46
when the valve
42
is unseated. The ECU then ceases the activation of the solenoid
48
after a calculated duration. Hence, the valve
42
returns to the initial position where it is seated on the valve seat
44
and closes the opening
34
, i.e., the injection nozzle
46
, again.
As is apparent from the descriptions provided above, the fuel injector
30
is a normally closed type. Although this type is easy to be controlled relative to a normally open type injector, it gives rise to a problem if the engine is not operated for a certain period of time, particularly, under a high temperature condition.
The problem is that the fuel residual in the opening
34
will congeal if the fuel injector
30
does not spray the fuel for a relatively long period of time. That is, if the fuel is gasoline, it will evaporate and escape through a clearance between the valve
42
and the valve seat
44
. However, impurities or heavy oil components that are intermixed in the gasoline will remain in the opening
34
and deposit on the valve
42
and valve seat
44
. The deposit of the heavy oil components acts as a kind of adhesive and the valve
42
occasionally adheres to the valve seat
44
. High temperature may expedite this situation. The longer the time in which the injector
30
remains idle, the stronger the degree of adhesion will be. Also, the higher the fuel pressure is, the harder the bond will be.
If the adhesion occurs, the fuel injector may not work and the engine consequentially cannot function properly. Occasionally, by pushing the valve
42
from the nozzle
46
, the problem of this adhesion may be resolved. However, this manner of repair may damage the valve
42
and invite a need to dissemble and repair the fuel injector
30
.
After the engine has started, the solenoid
48
is powered by a generator. However, at the moment of the engine starting, the generator is not driven by the engine and only a battery can supply power to the solenoid
48
. The battery under this condition, however, must supply power also to other electrical equipment such as, for example, a starter motor and fuel pumps. As a consequence, the power to the solenoid
48
is reduced and the separation or release of the valve
42
from the valve seat
44
is more difficult when starting the engine.
Another type of fuel injector exists that has no magnet core. In this type, the plunger
38
is simply drawn by the solenoid when it is magnetized. However, the aforementioned problem also can occur in this type of fuel injector.
This problem is exacerbated when used on an outboard motor, as compared to other land vehicles. The engine for a land vehicle (e.g., an automobile) can easily be designed such that the injection nozzle
46
of the fuel injector
30
are directed downward. In this arrangement, the fuel residual may leak out through the valve clearance with its own weight. However, if the engine is applied to an outboard motor, it is somewhat difficult for the fuel residual to pass through the clearance because the fuel injector
30
is laid generally horizontally and the clearance is usually only about 50 to 100 &mgr;m. Hence, the weight of the fuel residual does not help it pass through the clearance. Also, a drive unit of the outboard motor is arranged to be tilted up and down. When the drive unit is tilted up, in certain arrangement of the fuel injector
30
, the injection nozzle
46
is directed upwardly. This arrangement aggravates the situation described above.
SUMMARY OF THE INVENTION
An aspect of the present invention thus involves the recognition that a need therefore exists for an improved fuel injection system that can easily release a valve from a valve seat in a fuel injector to ensure that the engine starts properly after a long period of non-use (i.e., inactivity).
In accordance with one aspect of the present invention, a fuel injection system is provided for an internal combustion engine. The engine has a cylinder body defining a cylinder bore in which a piston reciprocates. A cylinder head is affixed to an end of the cylinder body and defines a combustion chamber with the cylinder head and the piston. The fuel injection system comprises at least one fuel injector spraying fuel through at least one opening for supplying the fuel to the combustion chamber. The fuel injector includes a valve that is movable between a closed position and an open position to regulate fuel flow through the opening. An actuator mechanism includes at least one actuator that is coupled to valve to move the valve from the closed position. A first power supply is provided to supply power to the actuator under an normal operating condition of the engine. A second power supply is provided to supply greater power to the actuator than the power supplied by the first power supply. A switchover device is provided to selectively change the supply of power to the actuator between the first power supply and the second power supply.
I
Dolinar Andrew M.
Knobbe Martens Olson & Bear LLP
Sanshin Kogyo Kabushiki Kaisha
LandOfFree
Fuel injection system for engine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fuel injection system for engine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fuel injection system for engine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3045433