Internal-combustion engines – Combustion chamber means having fuel injection only – Having a particular relationship between injection and...
Reexamination Certificate
2000-01-13
2001-05-29
Argenbright, Tony M. (Department: 3747)
Internal-combustion engines
Combustion chamber means having fuel injection only
Having a particular relationship between injection and...
C123S02700A, C123S14300R, C123S406520, C123SDIG007
Reexamination Certificate
active
06237562
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method of controlling a compression ignition internal combustion engine in which a mixture of air, and fuel, such as gasoline or gas oil, is burned by compression ignition.
2. Description of the Prior Art
In general, in a compression ignition internal combustion engine, fuel is burned at a higher compression ratio and at a larger or leaner air-fuel ratio (subjected to lean burn) than in a spark ignition internal combustion engine, whereby excellent fuel economy and heat efficiency are attained. Conventionally, a method of controlling this kind of compression ignition internal combustion engine was proposed e.g. by Japanese Laid-Open Patent Publication (Kokai) No. 9-287528. According to this control method, when the engine is in a low-load operating condition, intake air is heated by an electric heater arranged in an intake pipe, whereby the temperature of gases or air taken in is increased for quicker ignition of an air-fuel mixture supplied to the engine.
The heating of intake air is carried out for the following reason: In the compression ignition internal combustion engine, during low-load operation of the engine, such as idling, the temperature of the compression chamber is decreased and hence the timing of ignition is largely retarded, resulting in an unstable combustion of the engine. Particularly when a gasoline having a high octane value is used as fuel, a misfire can occur eventually. Therefore, according to this control method, when the engine is in a low-load operating condition, to ensure stability of combustion of the engine, intake air is heated e.g. by the above-mentioned electric heater to advance the timing of ignition of the mixture.
According to the above conventional control method, it is required to operate the electric heater to maintain stability of combustion during the low-load operation of the engine, and hence consume an increased amount of power, which results in an increase in running costs. At the same time, manufacturing costs of the internal combustion engine are also increased by the cost of provision of the electric heater. Further, in the compression ignition internal combustion engine, it is difficult to ignite the mixture by compression ignition when the engine is started at a low temperature, so that it is required to operate the electric heater for a long time period and set the compression ratio to a considerably high value so as to ensure excellent startability. However, if the electric heater is operated over such a long time period, power consumption is still more increased. Further, to set the compression ratio to the considerably high value, it is required to increase thickness of operating components such that strength thereof is ensured, and enhance sealing properties between pistons and cylinders. The resulting increase in inertial mass of the operating components increases inertial resistance, and the enhanced sealing properties of the associated components increase friction therebetween, which results in lower fuel economy.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method of controlling a compression ignition internal combustion engine, which is capable of reducing running and manufacturing costs and enhancing fuel economy while maintaining stability of combustion of the engine e.g. during a low-load operation of the engine and ensuring excellent startability and drivability of the same.
To attain the above object, the present invention provides a method of controlling a compression ignition internal combustion engine which allows switching of combustion of an air-fuel mixture between compression ignition combustion for burning the air-fuel mixture by compression ignition and spark ignition combustion for burning the air-fuel mixture by spark ignition, in dependence on an operating condition of the engine.
The method according to the invention is characterized by comprising progressively retarding ignition timing of the spark ignition when the switching of the combustion is carried out from the spark ignition combustion to the compression ignition combustion, to thereby control the switching of the combustion to the compression ignition combustion.
According to this method, the switching of combustion between the compression ignition combustion and the spark ignition combustion can be carried out in dependence on the operating condition of the compression ignition internal combustion engine. Therefore, by controlling the combustion of the engine such that the spark ignition combustion is carried out when the engine is started or when it is in a low-load operating condition, during which it is difficult to ignite the mixture by compression ignition, and that the compression ignition combustion is carried out when the engine is in other operating conditions, it is possible to maintain stability of combustion during low-load operation of the engine, and ensure startability of the same without heating intake air or the air-fuel mixture or further enhancing the compression ratio of the air-fuel mixture, as in the conventional control method in which only the compression ignition combustion is carried out. This advantageous effect of the present invention makes it possible to dispense with a construction for heating intake air or the mixture, thereby contributing to reduction of manufacturing costs and running costs. Further, since it is not required to enhance the compression ratio, it is possible to reduce the inertial mass of operating components and friction between the pistons and their associated cylinders, and hence improve fuel economy. Moreover, according to the method of the invention, in the switching of combustion from the spark ignition combustion to the compression ignition combustion, the timing of the spark ignition i.e. generation of sparks is progressively retarded from timing for the spark ignition combustion, to timing in which compression ignition takes place prior to spark ignition. Therefore, suitable ignition timing can be ensured for smooth transition from the spark ignition combustion to the compression ignition combustion. In this case, as the ignition timing is progressively retarded, pressure generated by the combustion or output torque of the engine is progressively decreased, so that it is possible to minimize the range of torque variation (stepped torque change) occurring in the transitional state, and at the same time, effect the switching of the combustion to the compression ignition combustion when the output torque of the engine is small. Therefore, it is possible to carry out smooth transition to the compression ignition combustion while maintaining excellent drivability of the engine.
Preferably, when the switching of the combustion is carried out from the spark ignition combustion to the compression ignition combustion, an amount of intake air is increased to a larger value thereof for the compression ignition combustion than a value thereof for the spark ignition combustion, to thereby control an air-fuel ratio of the air-fuel mixture to a larger value thereof.
According to this preferred embodiment, when the combustion is switched from the spark ignition combustion to the compression ignition combustion, the amount of intake air is increased from a value thereof assumed in the spark ignition combustion, to thereby increase the air-fuel ratio of the air-fuel mixture to a larger value than a value thereof assumed in the spark ignition combustion. Therefore, by increasing the amount of intake air such that the resulting air-fuel ratio becomes suitable for the compression ignition combustion, it is possible to obtain the advantageous effect of the compression ignition combustion. That is, it is possible to cause the compression ignition internal combustion engine to operate at a leaner air-fuel ratio during the compression ignition combustion than during the spark ignition combustion, thereby maintaining excellent fuel economy and heat efficiency.
More preferably, after completion of ret
Awasaka Moriyoshi
Sasaki Takashi
Ueda Kazuhiro
Arent Fox Kintner & Plotkin & Kahn, PLLC
Argenbright Tony M.
Honda Giken Kogyo Kabushiki Kaisha
LandOfFree
Method of controlling compression ignition internal... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of controlling compression ignition internal..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of controlling compression ignition internal... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2469195