Internal-combustion engines – Charge forming device – Fuel injection system
Reexamination Certificate
2001-09-25
2003-06-10
Kwon, John (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel injection system
C123S491000, C123S479000
Reexamination Certificate
active
06575143
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention pertains to a batteryless fuel injection apparatus for a multi-cylinder internal combustion engine for driving an injector injecting a fuel into an intake pipe or a cylinder of a multi-cylinder internal combustion engine by an output of a generator driven by the engine without using any battery.
BACKGROUND OF THE INVENTION
Such a fuel injection apparatus comprises an injector in the form of an electromagnetic fuel injection valve provided for each of the cylinders of the multi-cylinder internal combustion engine to inject the fuel into the intake pipe or the cylinder, a fuel pump to supply the fuel to the injector, an electric power circuit using an AC generator serving as an electric power source to generate a constant DC voltage, a signal generation device to generate pulse signals including a reference pulse signal for each of the cylinders which is generated at a reference rotational angle position set relative to each of the cylinders of the internal combustion engine and an electronic control unit (ECU) to receive an output of the signal generation device and outputs of various sensors such as a cooling water temperature sensor, an intake pipe internal pressure sensor, an air flow quantity sensor and so on serving to detect the conditions of the engine to control the injector for each of the cylinders using an output voltage of the electric power circuit as an electric power voltage.
The ECU generally comprises a microcomputer and includes cylinder judgment means to judge which cylinder each of the reference pulse signal generated by the signal generation device corresponds, injection quantity arithmetical operation means to arithmetically operate a fuel injection quantity from the injector for each of the cylinders using an rotation information of the engine obtained from the pulse signals generated by the signal generation device and various control conditions obtained from the various sensors, steady-state injection command generation means to generate an injection command signal for each of the cylinders having a signal width necessary for injecting the fuel from the injector for each of the cylinders in the injection quantity arithmetically operated by the injection quantity arithmetical operation means at the injection start position for each of the cylinders determined relative to the generation position of the reference pulse signal for each of the cylinders judged by the cylinder judgment means and an injector drive circuit to supply to the injector for each of the cylinders a drive current of valve-open level or higher using the output voltage of the electric power circuit as an electric power voltage while the injection command signal for each of the cylinders is generating.
The injector comprises a valve body having a fuel injection port at its leading end, a valve to open and close the fuel injection port of the valve body and an electromagnet for driving the valve body disposed within the valve body. The valve body is opened to inject the fuel while the drive current of valve-open level or higher is being supplied to the electromagnet.
The injector drive circuit to supply the drive current to the injector comprises a switch that gets an on-state while the injection command signal of rectangular waveform is being applied. The drive current flows from the electric power circuit through the switch to a drive coil for the injector.
Since a pressure of the fuel applied to the injector is normally kept constant by a pressure regulator, the injection quantity of the fuel from the injector is determined by the signal width of the injection command signal that corresponds to the fuel injection time.
In order to judge which cylinder each of a series of reference pulse signals generated by the signal generation device corresponds to, it is known that the signal generation device is adapted to generate a distinguishable cylinder judgment signal (a signal different from the reference pulse signals in its pulse width and its generation distance) which can be recognized by the ECU immediately before a reference rotational angle position of the specific cylinder (a rotational angle position of a crankshaft when a piston of the specific cylinder reaches the reference position for determining the ignition position and the fuel injection start position) to recognize that the reference pulse signal generated immediately after the cylinder judgment signal is detected is one corresponding to the specific cylinder or that a cylinder judgment signal generation device to generate a cylinder judgment signal (a signal generating once per one ignition cycle of the engine) is provided in addition to the signal generation device to generate the reference pulse signal to recognize that the reference pulse signal generated immediately after the cylinder judgment signal generation device generates the cylinder judgment signal corresponds to the specific cylinder.
Thus, it cannot be generally judged which the reference pulse signal corresponds to immediately after the starting operation begins when the engine should start, which will be referred to just as that the cylinder is judged later and the cylinder cannot be judged until the cylinder judgment signal is detected after the starting operation begins.
As aforementioned, the fuel injection apparatus for the multi-cylinder internal combustion engine is provided with the cylinder judgment means to judge which cylinder each of a series of the reference pulse signals generated by the signal generation device corresponds to determine the fuel injection start position of the injector for each of the cylinders based on the reference pulse signal for each of the cylinders judged by the cylinder judgment means. Thus, since the ECU cannot judge the cylinder for a while after the starting operation of the engine begins, the ECU simultaneously applies the injection command signals to all the injectors for the cylinders when each of the reference pulse signals is generated while the cylinders cannot be judged so that all the injectors for the cylinders simultaneously inject the fuel.
In case that the aforementioned fuel injection apparatus is used for a vehicle driven by the internal combustion engine and having no battery mounted thereon, the injector and the ECU are driven using a generator driven by the internal combustion engine as an electric power source.
As aforementioned, in some vehicle driven by the internal combustion engine having no battery mounted thereon, the injectors for all the cylinders are simultaneously operated when the engine starts. However, since the time for which the fuel is injected is so set longer as to improve the startability of the engine when it starts, the simultaneous operation of the injectors for all the cylinders tends to make the load of the generator excessive. In addition thereto, in the vehicle having no battery mounted thereon, since the engine is put into operation by human power using a recoil starter or a kick starter, the output voltage of the generator varies when the engine starts, which tends to cause the electric power voltage for the ECU or the injectors to be unstable. Thus, some internal combustion engine having the batteryless fuel injection apparatus used stops the operation of the ECU or repeat the stop of the operation and the resumption thereof due to the electric power voltage for the ECU lower than the minimum operation voltage therefor so that the injection of the fuel is not positively made and the engine fails to start. Even if the ECU can continue to be operated, the engine may be hard to start because the quantity of injection of the fuel is insufficient for the engine to start as the drive voltage of the injectors is lowered.
As the stop of the operation of the ECU and the resumption thereof are repeated when the engine starts, the simultaneous injection of the fuel into all the cylinders causes the fuel to be injected in the excessive amount, the ignition coils tend to be wet with the fuel, which sometimes disables the engine to start
Arakawa Yoshinobu
Sasaki Kouji
Tsukada Yoshikazu
Uemura Kiyoshi
Kokusan Denki Co. Ltd.
Kwon John
Pearne & Gordon LLP
LandOfFree
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