Internal-combustion engines – Accessories – Covers – trays – vibrators – corrosion inhibitors – air filters
Patent
1993-09-28
1995-06-20
Kamen, Noah P.
Internal-combustion engines
Accessories
Covers, trays, vibrators, corrosion inhibitors, air filters
123481, F02B 7700
Patent
active
054253357
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates in general to an automobile engine, and more particularly to an automobile engine having a mechanism for selectively disconnecting some cylinders by interrupting their associated inlet and exhaust valve systems.
DESCRIPTION OF THE RELATED ART
There is known an internal combustion engine which includes valve interrupting mechanisms for selectively stopping the air and fuel supply for some cylinders so as to reduce engine output and accomplish a substantial saving of fuel. According to various engine operational data, a control unit controls the valve interrupting mechanisms so as to interrupt the operation of inlet and exhaust valves of certain cylinders and stop the air and fuel supply thereto once the engine is operating under a particular condition. When the engine gets out of such a particular condition, the control unit resumes the operation of the interrupted valves, thereby allowing the air and fuel supply for the previously disconnected cylinders.
In the case of a 4-cylinder engine, for example, cylinders such as No. 1 and another cylinder having the same piston stroke are disconnected during the operation of the engine, thereby accomplishing a substantial saving of fuel. The foregoing operation mode is called "partial or two-cylinder operation mode" hereinafter.
The cylinders to be disconnected are determined according to a map which is used to select the full or partial cylinder operation mode and is plotted based on an engine speed and load data such as volumetric efficiency of air in the cylinders.
Generally speaking, not only ordinary automobile engines, but also the engine with the partial cylinder operation function, have to maintain their normal combustion performance during idling. For instance, when the partial operation mode is selected to improve fuel efficiency during the idling, fuel may be saved by 30% to 40%. However, in the 4-cylinder engine, a return torque of the engine under the two-cylinder operation, shown by a dotted line in FIG. 18, is less than the return torque (shown by a solid line) of the engine under the four-cylinder operation. As a result, the engine under the two-cylinder operation tends to suffer from unstable idle speed when external disturbances are applied.
During the partial cylinder operation, the engine suffers from a reduced inertia efficiency of intake air due to fewer active cylinders for the combustion stroke, and the volumetric efficiency becomes too small to efficiently produce a sufficient output.
When the engine is idling with some cylinders disconnected, it suffers from unstable idling speed or stall if an air-conditioner or a power steering is actuated.
It is therefore an object of the invention to provide an automobile engine which can overcome the foregoing problems of conventional engines with the partial cylinder operation. Especially, when the partial operation mode is selected during the idling, the engine happens to reduce its rotational speed for some reason. In such a case, the partial cylinder operation mode is canceled so as to protect the engine against the foregoing problems.
In the engine with the partial cylinder operation, a switchover mechanism is used for switching the full cylinder operation mode over to the partial cylinder operation mode or vice versa. For example, a hydraulic mechanism is employed to enable and disable the movement of plungers within rocker shafts. Sometimes times the engine is required to return to its previous operation mode immediately after it is set to either the full or partial cylinder operation mode. In other words, when the engine is operating under a state which is near the border between the full cylinder operation mode and the partial cylinder operation mode, the engine has to be frequently switched over between these two modes.
In such a case, the plungers should momentarily change their positions. The plungers should be released before they are completely engaged with their mating members in the rocker shafts. In another case, the plungers have to b
REFERENCES:
patent: 4274382 (1981-06-01), Sugasawa et al.
patent: 4459960 (1984-07-01), Ueno et al.
patent: 4608952 (1986-09-01), Morita et al.
patent: 5105779 (1992-04-01), Thompson
Chamoto Tetsuo
Iida Kazumasa
Miyamoto Katsuhiko
Kamen Noah P.
Mitsubishi Jidosha Kogyo Kabushiki Kaisha
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