Internal-combustion engines – Combustion chamber means having fuel injection only – Having a particular relationship between injection and...
Reexamination Certificate
1999-01-25
2001-06-12
Dolinar, Andrew M. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Having a particular relationship between injection and...
C123S1690CL, C123S179500, C123S625000, C313S13100A
Reexamination Certificate
active
06244247
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ignition device for use in an internal combustion engine, and particularly concerns to an ignition device which establishes spark discharges in a spark plug except for the time when the air-fuel mixture is normally ignited to facilitate the self-cleaning action due to the spark discharges so as to burningly remove the carbon fouling of the spark plug.
BACKGROUND OF THE INVENTION
In an ignition device, an engine control device is generally provided to produce an ignition signal to feed it to an igniter so as to cause spark discharges in the spark plug at a predetermined ignition time during a compression stroke based on an electrical signal which is generated to detect which stroke each of cylinders occupies by means of a sensor such as, for example, cam position sensor.
In an in-cylinder fuel injection type engine, one of the features of this engine is that fuel is injected through the compression stroke (referred to as “compression stroke injection” hereinafter) to contribute to low fuel consumption. In order to implement the compression stroke injection, it is necessary to determine a fuel injection timing close to a predetermined ignition time during a compression stroke so as to ignite the air-fuel mixture staying around the spark plug exposed to a combustion chamber as shown by laid-open Japanese Patent Application Nos. 58-178835 and 4-183922.
However, due to the compression stroke injection, the carbon fouling is likely to occur in the spark plug because the fuel is injected near at the predetermined ignition timing time while the cylinder temperature is yet to be risen to a satisfactory degree.
Additionally, the spark plug usually has an ability to burningly remove or fall off the carbon deposit piled on an insulator by means of self-cleaning action due to the spark discharges so as to prevent the insulation resistance (in terms of M &OHgr;) from unfavorably dropping.
However, the self-cleaning action does not work enough to expel the carbon fouling particularly at the time of starting, cold starting, immediately after cold starting or running along streets in cold region areas. When allowing the carbon fouling to deposit on the insulator, the insulation resistance (in terms of M &OHgr;) drops as shown in
FIG. 38
to deteriorate the engine condition so as to invite engine stall, unfavorable idling, poor driveability or starting failure.
Therefore, it is one of the objects of the invention to provide an ignition device which is capable of maintaining a good self-cleaning action when the spark plug is likely to be smoldered at the time of starting the engine, or especially cold starting the engine.
DISCLOSURE OF THE INVENTION
First Aspect of the Invention
According to the invention, there is provided an ignition device which causes at least once spark discharge in a spark plug and having a state distinction means provided to judge whether an engine is in a cold or normal state, comprising: means provided to establish at least once the spark discharge in the spark plug at the time of igniting an air-fuel mixture and at the time of except for igniting the air-fuel mixture when said state distinction means judges that the engine is in the cold state.
The spark plug is placed in an internal combustion engine and electrically connected to a secondary coil of an ignition coil. A primary coil of the ignition coil is, for example, connected to an igniter and further connected to an engine control device which generates an ignition signal to the igniter.
By on-off actuating an electric current flowing through the primary coil based on the ignition signal generated from the engine control device, it is possible to control the timing in which the spark plug produces spark discharges.
With the use of e.g., a stroke distinction means provided to detect which stroke a specified cylinder occupies, it is possible to judge which timing the spark plug is to produce the spark discharges in order to ignite the air-fuel mixture.
Operation and Advantages of the First Aspect of the Invention
When the state distinction means judges that the engine is in the cool state upon cold starting the engine or running the engine along the streets in cold region areas,it allows the spark plug to produce at least once the spark discharge at the time except for igniting the air-fuel mixture.
Namely, by increasing the fuel component against the aerial component, it is possible to stabilize the starting condition upon cold starting the engine or running the engine along the streets in cold region areas in which the air-fuel mixture is hard to vaporize quickly. In this instance, the carbon deposit is likely to pile on the insulator due to an incomplete combustion when increasing the fuel component against the aerial component. However, it is possible to burningly remove or fall off the carbon deposit by producing the spark discharges at the time when the spark discharges have no affect on the ignition against the air-fuel mixture, thus improving the self-cleaning action due to the spark discharges in the spark plug. This makes it possible, to avoid the progress of the carbon fouling with relatively high insulation resistance (in the context of M &OHgr;) generally maintained so as to dissolve the unfavorable condition upon starting the engine in the cold state.
When judged that the engine is in the normal state in which the engine is warmed up, the spark discharges occur in the spark plug at the time only when the air-fuel mixture is to be ignited. This returns the timing of establishing the spark discharges to the normal condition so as to insure a good spark erosion resistant property with the spark plug.
Second Aspect of the Invention
According to the invention, the ignition device has means to establish at least once the spark discharge in the spark plug at the time of igniting the air-fuel mixture and during a period length from a time of igniting the air-fuel mixture to a time of beginning to inject the fuel.
Operation and Advantages of the Second Aspect of the Invention
Namely, by increasing the fuel component against the aerial component, it is possible to stabilize the starting condition upon cold starting the engine or running the engine along the streets in cold region areas in which the air-fuel mixture is hard to vaporize quickly. In this instance, the carbon deposit is likely to pile on the insulator due to an incomplete combustion when increasing the fuel component against the aerial component. However, it is possible to burningly remove or fall off the carbon deposit by producing at least once the spark discharge at the time when the spark discharges have no affect on the ignition against the air-fuel mixture, thus improving the self-cleaning action due to the spark discharges in the spark plug. This makes it possible to avoid the progress of the carbon fouling with relatively high insulation resistance (M &OHgr;) generally maintained so as to dissolve the unfavorable condition upon operating the engine in the cold state.
Particularly in the internal combustion engine in which the fuel is directly injected into the combustion chamber, the establishment of the spark discharges has a forthright influence on igniting the air-fuel mixture upon starting to inject the fuel. For this reason, the timing length which has no influence on igniting the air-fuel mixture is during the period from the time of igniting the air-fuel mixture to the time of beginning to inject the fuel.
When having warmed up the engine, the state distinction means judges that the engine is in the normal state.In this instance, the spark discharge occurs at least once in the spark plug at the time only when the air-fuel mixture is ignited. This returns the timing of establishing the spark discharges to the normal condition so as to insure the good spark erosion resistant property with the spark plug.
Third Aspect of the Invention
According to the invention, the ignition device further has a starting distinction means provided to judge whether said engine is in a starting s
Kokubu Akio
Matsubara Yoshihiro
Suzuki Tetsusi
Yoshida Kazumasa
Dolinar Andrew M.
NGK Spark Plug Co. Ltd.
Sughrue Mion Zinn Macpeak & Seas, PLLC
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