Internal-combustion engines – Charge forming device – Fuel injection system
Patent
1995-06-07
1996-02-20
Nelli, Raymond A.
Internal-combustion engines
Charge forming device
Fuel injection system
F02D 700
Patent
active
054921007
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a fuel control device for an internal combustion engine in which a valve system includes valve change-over mechanisms for selectively activating or de-activating intake and exhaust valves in a full or partial cylinder operation mode, and allows a fuel supply unit to supply fuel to active cylinders according to the full or partial cylinder operation mode.
DESCRIPTION OF THE RELATED ART
There are known internal combustion engines which include: valve change-over mechanisms for selectively operating low or high speed cams at appropriate timings so as to increase engine output; or valve change-over mechanisms for selectively operating low or high speed cams, operating valves by the selected cams, and allowing a partial cylinder operation mode by interrupting supply of intake air and fuel to only a part of cylinders, thereby increasing engine output and reducing fuel consumption.
A control device for such valve change-over mechanisms sets various operation modes according to engine operation condition data. For instance, part of the cylinders are disconnected in a partial cylinder operation mode by de-activating intake and exhaust valves of such cylinders and interrupting fuel supply thereto. At the completion of the partial cylinder operation mode, the disconnected cylinders become active with their intake and exhaust valves activated and fuel being supplied thereto. Further, in a full cylinder operation mode (with all the cylinders activated) at a low engine speed, low speed cams are used to operate the intake and exhaust valves so as to increase volume efficiency. Conversely, high speed cams are used to operate the valves in the full cylinder operation mode at a high engine speed, thereby increasing the volume efficiency.
The foregoing control device is required to quickly control the valve change-over mechanisms and the fuel supply system in response to various engine operating condition data. In the valve system, the valve change-over mechanisms are activated by solenoid valves or a hydraulic circuit driven by the solenoid valves. There is no trouble so long as the valve change-over mechanisms are very responsive to the engine operating conditions. The valve change-over mechanisms are, however, prone to poor response due to aging of components thereof.
When the partial cylinder operation mode is changed over to the full cylinder operation mode, the intake and exhaust valves of the disconnected cylinders resume their operation immediately. In this state, if the valve change-over mechanisms are slow to respond to such change of the engine operation mode due to malfunction of components thereof, the control device for the valve change-over mechanisms controls the valves for the full cylinder operation mode while the valve system may continue to operate the valves for the partial cylinder operation mode. In such a case, there will be no trouble if there is a sensor which can directly detect the operating conditions of the valves. However, such a sensor has not yet been available for practical use.
If the valve system operates for the partial cylinder operation mode but the fuel supply unit continues fuel supply to all the cylinders for the full cylinder operation mode, the fuel supplied to the disconnected cylinders would go into the continuously active cylinders via the surge tank and damage pistons or connecting rods thereof.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to provide a fuel control device, which can continuously supply fuel only to the active cylinders in the partial cylinder operation mode except when it is confirmed that the valve system is fully responsive to the change-over from the partial cylinder operation mode to the full cylinder operation mode.
According to the invention, there is provided a fuel control device for an engine having disconnectable groups of cylinders, comprising: valve change-over units for selectively activating or de-activating at least either intake or exhaust valves of the engine; an ope
REFERENCES:
patent: 4552114 (1985-11-01), Sano et al.
patent: 4637363 (1987-01-01), Schmid
patent: 4781160 (1988-11-01), Lohr et al.
patent: 4951773 (1990-08-01), Poirier et al.
patent: 5337720 (1994-08-01), Murakami et al.
Ishii Dairoku
Maeda Tetsuo
Mitsubishi Denki & Kabushiki Kaisha
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
Nelli Raymond A.
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