Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...
Reexamination Certificate
1999-09-27
2001-06-19
Yuen, Henry C. (Department: 3747)
Internal-combustion engines
Charge forming device
Fuel flow regulation between the pump and the charge-forming...
C123S435000, C123S457000
Reexamination Certificate
active
06247455
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to an injection quantity control apparatus provided to an internal combustion engine, and in particular to an injection quantity control apparatus provided to an internal combustion engine in which fuel is continuously injected.
2. Description of the Related Art
Conventionally, as disclosed in “My Maintenance Note,” Naoyuki Yokoyama, Japan Aeronautical Engineers' Association, Jul. 10, 1981), there is known an injection quantity control apparatus provided to an internal combustion engine for an aircraft. This control device includes a first chamber and a second chamber.
The first chamber is divided into a static pressure chamber and a total pressure chamber by a first diaphragm. A static pressure and a total pressure generated in an intake pipe of the engine are introduced into the static pressure chamber and the total pressure chamber, respectively. Thus, a dynamic pressure is generated between the static pressure chamber and the total pressure chamber in accordance with a specific volume of intake air. Hereinafter, this dynamic pressure is referred to as a first differential pressure. A force is exerted on the first diaphragm in accordance with the first differential pressure.
The second chamber is divided into a back pressure chamber and a fuel chamber by a second diaphragm. A valve mechanism is provided in the fuel chamber. Fuel is delivered from the fuel chamber through the valve mechanism. Thus, an amount of fuel delivered from the fuel chamber is adjusted in accordance with an opening of the valve mechanism. The fuel chamber is supplied with fuel which is pumped up by a fuel pump through a mixture valve. An opening of the mixture valve can be changed by a mixture lever being manually operated by an operator. When fuel is delivered from the fuel chamber through the valve mechanism, a fuel pressure in the fuel chamber is decreased from a discharge pressure of the fuel pump by a value corresponding to a pressure drop across the mixture valve. On the other hand, the back pressure chamber is directly supplied with fuel discharged by the fuel pump. Thus, between the back pressure chamber and the fuel chamber, there is generated a differential pressure in accordance with the pressure drop across the mixture valve, that is, a differential pressure in accordance with a product of a flow resistance of the mixture valve and an amount of delivered fuel. Hereinafter, this differential pressure is referred to as a second differential pressure. A force in accordance with the second differential pressure is exerted on the second diaphragm.
A valve body of the above-mentioned valve mechanism is connected to the first and second diaphragms so that a first force generated by the first differential pressure is exerted thereon in a valve opening direction and a second force generated by the second differential pressure is exerted thereon in a valve closing direction. Thus, the valve mechanism is maintained to be in a state where the first and second forces are balanced. As mentioned above, the first differential pressure corresponds to a specific volume of intake air and the second differential pressure corresponds to an amount of fuel which is delivered from the fuel chamber. Thus, the injection quantity control apparatus can adjust an amount of fuel delivered therefrom in accordance with a specific volume of intake air. The fuel which is delivered from the injection quantity control apparatus is supplied to injection nozzles, and the nozzles continuously inject fuel into the respective intake pipes.
Additionally, the second differential pressure changes in accordance with an opening of the mixture valve, as mentioned above. Thus, it is possible to adjust an injection quantity by manually operating a mixture lever so that an opening of the mixture valve is changed.
While the aircraft is in flight, it is necessary to adjust the injection quantity so that a lean air-fuel ratio is achieved in view of improving fuel economy. However, according to the above-mentioned conventional injection quantity control apparatus, the operator must manually operate the mixture lever while monitoring, for example, an exhaust gas temperature. Such an operation forces a burden on a pilot of the aircraft.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an injection quantity control apparatus for an internal combustion engine which can achieve a desired air-fuel ratio without a necessity of a manual operation by an operator.
The object of the present invention can be achieved by an injection quantity control apparatus provided to an internal combustion engine having an injection nozzle which continuously injects fuel, the apparatus comprising:
a fuel quantity adjustment mechanism which has a static pressure chamber and a total pressure chamber to which a static pressure and a total pressure of an intake pipe of the engine are supplied, respectively, and adjusts an amount of fuel supplied to the injection nozzle in accordance with a dynamic pressure between a pressure of the static pressure chamber and a pressure of the total pressure chamber; and
a dynamic pressure corrector which corrects the dynamic pressure so that an air-fuel ratio of the engine is controlled to be substantially a target value.
In this invention, a dynamic pressure between the static pressure and the total pressure of the intake pipe corresponds to a specific volume of intake air. Thus, an injection quantity can be controlled in accordance with the specific volume of intake air since the fuel quantity adjustment mechanism adjusts the amount of fuel supplied to the injection nozzle in accordance with the dynamic pressure between the pressure of the static pressure chamber and the pressure of the total pressure chamber. Thus, according to the invention, a target air-fuel ratio can be achieved without a necessity of a manual operation by an operator.
The injection quantity control apparatus may further comprise an air density compensator which corrects the dynamic pressure in accordance with a density of intake air of the internal combustion engine. In this case, a change in the injection quantity due to a change in the density of intake air can be compensated for.
The dynamic pressure corrector may comprise:
a connecting passage which connects a static pressure supply passage for supplying the static pressure to the static pressure chamber and a total pressure supply passage for supplying the total pressure to the total pressure chamber;
a control valve which is provided to the connecting passage;
a first orifice which is provided to the total pressure supply passage or the static pressure supply passage at a position between the connecting passage and the intake pipe; and
a valve controller which controls the control valve based on an intake manifold pressure and an engine speed of the engine.
In view of improving a fail-safe performance against a failure of the control valve, the dynamic pressure corrector may further comprise a second orifice provided to the connecting passage in series with the control valve.
In this invention, the dynamic pressure &Dgr;P between the pressure of the static pressure chamber and the pressure of the total pressure chamber is equal to the dynamic pressure &Dgr;P
0
between the static pressure and the total pressure of the intake pipe multiplied by a sum of a flow resistance D
2
of the second orifice and a flow resistance D
3
of the control valve and divided by a sum of a flow resistance D
1
of the first orifice and the flow resistances D
2
and D
3
. That is, the dynamic pressure &Dgr;P is expressed by the following equation:
&Dgr;
P=&Dgr;P
0
·(
D
2
+D
3
)/(
D
1
+D
2
+D
3
)
Thus, when an opening of the control valve changes, the dynamic pressure &Dgr;P changes in accordance with a change in the flow resistance D
3
of the control valve. The valve controller controls the control valve based on the intake manifold pressure and the engine speed. Thus, the dynamic pressur
Hayashi Takashi
Otake Yukio
Kenyon & Kenyon
Toyota Jidosha & Kabushiki Kaisha
Vo Hieu T.
Yuen Henry C.
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