Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2003-06-03
2004-10-26
Kwon, John (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C701S115000, C123S406140, C123S435000
Reexamination Certificate
active
06810320
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an apparatus and method for diagnosing and controlling combustion in an internal combustion engine including a gas engine which is constituted so that fuel gas is mixed with air and burned in the combustion chamber thereof.
BACKGROUND ART
It is demanded in an internal combustion engine, particularly in a gas engine which uses clean gas such as town gas as main fuel, to sense with reliability the occurrence of knock due to misfire, flame quenching or uneven mixture in the combustion chamber and to take a measure to deal with the phenomenon without delay. Further, it is required in a gas engine, petrol engine, and diesel engine, etc. to detect positively the excessive increase of the maximum combustion pressure in the combustion chamber, i.e. the maximum cylinder pressure or the reduction of compression pressure in addition to misfire, flame quenching, or knock for maintaining the durability, stability of performance of the engine.
It is inevitable in a gas engine, petrol engine, and diesel engine, etc. that the condition of combustion in the combustion chamber is detected, diagnosed, and the ignition timing of the fuel and the fuel injection quantity are properly controlled according to the result of the diagnosis. Further, it is required that, even when something wrong occurs with the maximum cylinder pressure detector, which is the detector of the condition of combustion, there is speedy recovery from the abnormal condition and resumption of normal diagnosis and control of combustion.
Combustion diagnosis systems for detecting and diagnosing the condition of combustion in the combustion chamber of internal combustion engines are disclosed in Japanese Patent Application Publication No.2000-110652, No.11-183330, and Japanese Patent No.2712332, etc.
According to Japanese Patent Application Publication No.2000-110652, a frequency band is determined according to the now-operating parameter of the internal combustion engine, the signal component of frequencies belonging to the extraction frequency band is extracted from the detected signal of cylinder pressure by means of a filter, and knock is judged to be occurring when the extracted component exceeds a threshold value.
In Japanese Patent Application Publication No.11-183330, misfire is judged to be present when the crank angle when the value of the pressure in the detected signal from the cylinder pressure detector is maximum, i.e. the crank angle at the maximum cylinder pressure is in the range of a predetermined crank angle and at the same time the mean effective pressure calculated from the detected cylinder pressure signal is below the predetermined value.
According to Japanese Patent No.2712332, engine rotation speed is detected to monitor the change thereof, and misfire is judged to be present when engine rotation speed has gone below the predetermined value.
However, in the invention of Japanese Patent Application Publication No.2000-110652, the signal component of frequencies belonging to the extraction frequency band is extracted by a filter means, so complicated computation processing such as changing of a pass band accompanying the treatment by the filter means is necessary. Therefore, the judgement of the occurrence of knock and control thereof are complicated. Further, as the absolute value of the cylinder pressure is necessary, the accuracy of the detected cylinder pressure decreases and correct diagnosis of combustion is impossible when the output level of the cylinder pressure sensor reduces totally due to deterioration, temperature drift, failed calibration, etc. of the cylinder pressure sensor.
Also in the invention of Japanese Patent Application Publication No.11-183330, the absolute value of the cylinder pressure is necessary for the judgement of misfire, so, in an analogous fashion as mentioned above, the accuracy of the detected cylinder pressure decreases and correct diagnosis of combustion is impossible when the output level of the cylinder pressure sensor reduces totally due to the deterioration, temperature drift, failed calibration, etc. of the cylinder pressure sensor.
In the invention of Japanese Patent No.2712332, the condition of combustion in the combustion chamber is detected and diagnosed by the indirect means of monitoring the change of rotation speed of the engine, so the accuracy of combustion diagnosis is low.
Further, in any of the prior inventions, an apparatus carries out combustion diagnosis only on one item, that is knock or misfire, and therefore the cost of the apparatuses becomes expensive to provide for a plurality of diagnosis functions.
In a multi-cylinder gas engine provided with an ignition device among these internal combustion engines, combustion efficiency increases and engine performance improves by advancing the fuel ignition timing. However, knock occurs more easily due to the earlier spontaneous ignition of unburned fuel. Therefore, it is required to operate with a fuel ignition timing with which knock is evaded and the maximum engine performance is maintained.
It is required, in a multiple-cylinder gas engine like this, to carry out the combustion diagnosis and combustion control so that, through the detection of the occurrence of misfire or flame quenching with good accuracy without delay from the detected data of the cylinder pressure, the fuel ignition timing and fuel injection quantity for the cylinder in which the misfire or flame quenching is occurring are adjusted to deal with the misfire or flame quenching so as to make the smooth operation of the other cylinders possible without being affected by the cylinders in which the misfire or flame quenching is occurring.
Further, in the multi-cylinder gas engine, it is required that, when abnormality occurs to any of the cylinder pressure detecting means for detecting the combustion condition in a combustion chamber due to any failure of the detecting means, the recovery of the function of the cylinder pressure detecting means is carried out while adjusting the fuel ignition timing and fuel injection quantity of the cylinder in which the abnormality in the pressure detecting means has occurred to conditions safe against abnormal combustion. After the recovery of the function of the pressure detecting means the normal combustion control is recovered automatically, and thus the occurrence of abnormality in any of the cylinder pressure detecting means can be dealt with without stopping the operation of the engine.
Further, in the multi-cylinder gas engine, it is required that the standard values (thresholds) of diagnosis items such as maximum cylinder pressure, maximum limit pressure of knock, and permissible pressure concerning occurrence of flame quenching are adjustable to match the operation condition of the engine and a high accuracy of diagnosis of the conditions of combustion is maintained.
Further, in the multi-cylinder gas engine, it is required that the occurrence of abnormality in any of the cylinder pressure detecting means can be detected at an early stage and automatically, swift recovery of the function of the cylinder pressure detecting means from the abnormal state is possible, and the combustion diagnosis is carried out smoothly.
However, none of prior arts, including the prior invention, provides a combustion diagnosis and combustion control means which can satisfy the requirements mentioned above.
Particularly, when the information of combustion diagnosis such as misfire and flame quenching is sent to a combustion control device, the method of sending the information of a plurality of cylinders digitally through a serial wire is not desirable, for the influence of a break in the wire and noise affects the control of all of the cylinders.
For this reason, a method of parallel transmittal of each individual combustion diagnosis information between the combustion diagnosis apparatus and combustion control apparatus as shown in
FIG. 32
is thought of as a fail-safe. Several kinds of category's information (2
n
kinds) for each of m cylinders are necess
Murakami Akito
Nakayama Yoshihiro
Yamamoto Takayuki
Yasueda Shinji
Kwon John
Mitsubishi Heavy Industries Ltd.
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