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An apparatus diagnoses and controls combustion of an internal combustion engine which makes smooth operation of an engine possible by adjusting the combustion condition at the occurrence of knock, misfire, and flame quenching and also makes it possible to detect the occurrence of abnormality in cyli

An apparatus diagnoses and controls combustion of an internal combustion engine which makes smooth operation of an engine possible by adjusting the combustion condition at the occurrence of knock, misfire, and flame quenching and also makes it possible to detect the occurrence of abnormality in cylinder pressure detectors without delay and deal with the abnormality without stopping the operation of the engine. A maximum pressure ratio P p /P 0 is calculated, P p being the maximum cylinder pressure and P 0 being the compression pressure at one or a plurality of crank angles in the compression stroke P p /P 0 is compared with pressure ratios for each diagnosis category, the combustion conditions are diagnosed by judging the result of the comparison every cycle or plural cycles.

대표청구항 ▼

1. An apparatus for diagnosing and controlling combustion of an internal combustion engine in which fuel gas is mixed with air and burned in a combustion chamber, comprising:a cylinder pressure detector for detecting the pressure in the combustion chamber,a means for calculating the ratio of the max

1. An apparatus for diagnosing and controlling combustion of an internal combustion engine in which fuel gas is mixed with air and burned in a combustion chamber, comprising:a cylinder pressure detector for detecting the pressure in the combustion chamber,a means for calculating the ratio of the maximum cylinder pressure P p to the compression pressure or pressures P 0 at one or a plurality of predetermined crank angle in the compression stroke, which ratio P p /P 0 is the maximum pressure ratio from cylinder pressure detected by said cylinder pressure detector,a means for comparing the maximum pressure ratio P p /P 0 with pressure ratios predetermined stepwise for each category of diagnosis, each of said pressure ratios being hereafter referred to as a threshold pressure ratio, anda means for diagnosing a condition of combustion in the combustion chamber by judging the result of comparison. 2. The apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 1, wherein a plurality of said threshold pressure ratios are predetermined stepwise for each category of diagnosis, and each of said plurality of threshold pressure ratios is changed as a function of engine operating conditions including engine load, engine rotation speed, and inlet air temperature. 3. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 1, wherein a means is provided which judges that the combustion is abnormal when said maximum pressure ratio P p /P 0 is equal to or exceeds a predetermined maximum permissible pressure ratio P p0 or when the number of operation cycles N h when said maximum pressure ratio P p /P 0 is equal to or exceeds a predetermined pressure ratio P h1 , i.e., when P p /P 0 ≧P h1 , is equal to or exceeds a permissible number N h0 , i.e., when N h ≧N h0 . 4. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 1, wherein a means is provided which judges that compression pressure P 0 is abnormal when said compression pressure P 0 at a predetermined crank angle in the compression stroke is equal to or lower than a predetermined permissible compression pressure P c0 , i.e., when P 0 ≦P c0 . 5. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 1, wherein a means is provided which judges that knock has occurred in the combustion chamber when the number of cycles S n in which said maximum pressure ratio P p /P 0 is equal to or exceeds a predetermined permissible pressure ratio of knock P h1 , i.e., when P p /P 0 ≧P h2 in a plurality of cycles in the past is equal to or exceeds a permissible number S n0 i.e., when S n ≧S n0 . 6. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 1, including:a means for calculating the ratio of the maximum cylinder pressure P p to the compression pressure or pressures P 0 at a predetermined crank angle in the compression stroke, the pressures being determined based on the pressures detected by said cylinder pressure detector,a means for calculating the ratio of a pressure P 1 at a predetermined crank angle in the combustion stroke to said pressure P 0 at a predetermined crank angle in the compression stoke, which is a combustion pressure ratio (P 1 /P 0 ), anda means which judges that misfire has occurred when said maximum pressure ratio P p /P 0 is equal to or smaller than a predetermined minimum permissible pressure ratio P n , i.e., when P p /P 0 ≦P n , and at the same time said combustion pressure ratio P 1 /P 0 is equal to or smaller than a predetermined permissible pressure ratio P m of misfire, i.e., when P 1 /P 0 ≦P m . 7. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 1, including:a means for calculating the ratio of a lower side pressure P 2 in the combustion stroke, lower than a pressure P 1 at a predetermined crank angle in the combustion stroke, to said pressure P 0 at a predetermined crank angle in the combustion stroke P 2 /P 0 , anda means which judges that flame quenching has occurred in the combustion chamber when said maximum pressure ratio is equal to or smaller than a predetermined minimum permissible pressure ratio P n , i.e., when P p /P 0 ≦P n , a combustion pressure ratio P 1 /P 0 is equal to or smaller than a predetermined minimum permissible pressure ratio P m of misfire, and the combustion pressure ratio P 2 /P 0 is equal to or larger than the permissible pressure ratio P m1 of flame quenching. 8. A method of diagnosing and controlling combustion of an internal combustion engine including a gas engine which is constituted so that fuel gas is mixed with air and burned in a combustion chamber thereof, wherein the diagnosis of the condition of combustion in the combustion chamber is performed in such a manner in whichthe pressure in the combustion chamber is detected,a pressure difference ΔP between the detected pressure P and reference pressure P b , which is the pressure at or before the beginning of compression including inlet air pressure, ΔP=P−P b , is calculated for every a plurality of crank angles, anda standardized pressure ratio, which is the ratio of said pressure difference ΔP to a pressure difference ΔP 0 , ΔP 0 being the pressure difference between the pressure P 0 at one or a plurality of predetermined crank angle in the compression stroke and said reference pressure P b ΔP 0 =P−P b , is used for diagnosis of a combustion condition in the combustion chamber. 9. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 8, wherein said standardized pressure ratio ΔP/ΔP 0 in the cylinder is compared with a pressure ratio predetermined stepwise for each category of diagnosis, which pressure ratio is hereafter referred to as threshold pressure ratio, and the result of comparison is evaluated for every one or a plurality of cycles to diagnose the condition of combustion in the combustion chamber. 10. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 9, wherein the engine is stopped when said standardized pressure ratio ΔP/ΔP 0 at the maximum cylinder pressure P p , which is a standardized maximum pressure ratio ΔP p /ΔP 0 , is equal to or exceeds a predetermined permissible maximum pressure ratio P p0 , i.e., when ΔP p /ΔP 0 ≧P p0 . 11. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 9, wherein fuel ignition timing is retarded by a certain crank angle when said standardized maximum pressure ratio ΔP p /ΔP 0 is equal to or exceeds a predetermined maximum reference pressure ratio P sh , i.e., when ΔP p /ΔP 0 ≧P sh , and fuel ignition timing is advanced by a certain crank angle when said standardized maximum pressure ratio ΔP p /ΔP 0 is equal to or below a predetermined minimum reference pressure ratio P s1 , i.e., when ΔP p /ΔP 0 ≦P s1 . 12. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 9, wherein the engine is stopped when said pressure difference ΔP 0 at the predetermined crank angle in the compression stroke is equal to or smaller than a predetermined permissible compression pressure difference P c0 , i.e., when ΔP 0 ≦P c0 . 13. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 9, wherein the fuel ignition timing is retarded by a certain crank angle when said standardized maximum pressure ratio ΔP p /ΔP 0 is equal to or exceeds a predetermined permissib le pressure ratio P h2 of knock, i.e., when ΔP p /ΔP 0 ≦P h2 . 14. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 9, wherein misfire is judged to have occurred in the combustion chamber and the fuel injection for the cylinder in which misfire is judged to have occurred is shut off when said standardized maximum pressure ratio ΔP p /ΔP 0 is equal to or below a predetermined minimum permissible pressure ratio P n of misfire i.e., when ΔP p /ΔP 0 ≦P n . 15. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 9, wherein flame quenching is judged to have occurred and the fuel injection quantity for the cylinder in which flame quenching is judged to have occurred is increased when said standardized maximum pressure ratio ΔP p /ΔP 0 and a standardized combustion pressure ratio ΔP 1 /ΔP 0 in the combustion stroke are equal to or smaller than a minimum permissible pressure ratio P n and permissible pressure ratio P m of misfire, respectively, i.e., when ΔP p /ΔP 0 ≦P n and ΔP p /ΔP 0 ≦P m , and a standardized combustion pressure ratio ΔP 2 /ΔP 0 is larger than a permissible pressure ratio P m1 of flame quenching. 16. A method of diagnosing and controlling combustion of an internal combustion engine as in claim 9, wherein the standardized threshold pressure ratio cited in claim 9 is any one of a permissible maximum pressure ratio P p0 , maximum value P sh of maximum reference pressure ratio, permissible pressure ratio of knock P h2 , minimum pressure ratio of misfire P n , permissible pressure ratio of misfire P m , and permissible pressure ratio of flame quenching P m1 , and each said threshold pressure ratio and a compression pressure difference P c0 are variable as a function of engine load or engine rotation speed or engine operating conditions including inlet air temperature. 17. An apparatus for diagnosing and controlling combustion of an internal combustion engine including a gas engine which is constituted such that fuel gas is mixed with air and burned in a combustion chamber, comprising:a cylinder pressure detector for detecting the pressure in the combustion chamber,a crank angle detector for detecting crank rotation angles of the engine,a means for calculating the pressure difference ΔP between detected cylinder pressure P and a reference pressure P b at or before the beginning of compression including inlet pressure, ΔP=P−P b from the cylinder pressure detected by said cylinder pressure detector for every crank angle,a means for calculating standardized pressure ratio, which is the ratio of said pressure difference ΔP to the pressure difference ΔP 0 , i.e. ΔP/ΔP 0 , ΔP 0 being the pressure difference between the pressure P 0 at one or a plurality of predetermined crank angles in the compression stroke and said reference pressure P b , ΔP 0 =P−P b ,a means for diagnosing a condition of combustion in said combustion chamber using said standardized pressure ratio ΔP/ΔP 0 , anda combustion control apparatus for controlling the combustion condition of the engine on the basis of the result of the combustion condition diagnosis outputted from the combustion condition diagnosis means. 18. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 17, including:a means for comparing said standardized maximum pressure ratio ΔP p /ΔP 0 with a predetermined maximum permissible pressure ratio P p0 and outputting the result of the comparison, anda means for actuating an engine stopper to stop the engine when said result of comparison outputted from the combustion diagnosis apparatus is ΔP p /ΔP 0 ≧P p0 . 19. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 17, including:a means for comparing said standardized maximum pressure ratio ΔP p /ΔP 0 with a maximum value P sh of maximum reference pressure ratio and with a minimum value P s1 of maximum reference pressure ratio and outputting the result of the comparison, anda means for retarding ignition timing of fuel, including pilot fuel, by a certain crank angle when the result of said comparison is ΔP p /ΔP 0 >P sh and for advancing the ignition timing by a certain crank angle when the result of said comparison is ΔP p /ΔP 0 ≦P s1 . 20. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 17, including:a means for comparing said standardized maximum pressure ratio ΔP p /ΔP 0 with a predetermined permissible pressure ratio P h2 of knock and judging that knock has occurred when said standardized maximum pressure ratio ΔP p /ΔP 0 is equal to or exceeds said permissible pressure ratio P h2 of knock, anda means for retarding fuel ignition timing by a certain crank angle upon receipt of a judgement signal of the occurrence of knock. 21. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 17, including:a means for comparing said standardized maximum pressure ratio ΔP p /ΔP 0 with the predetermined permissible pressure ratio of misfire and judging that misfire has occurred in the combustion chamber when said standardized maximum pressure ratio ΔP p /ΔP 0 is equal to or smaller than a minimum permissible pressure ratio P n of misfire, anda means for cutting off fuel injection to a cylinder in which misfire has occurred upon receipt of a judgement signal of the occurrence of misfire. 22. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 19, including:a means for outputting a judgement signal of the occurrence of flame quenching in the combustion chamber when said standardized maximum pressure ratio ΔP p /ΔP 0 and a standardized combustion pressure ratio ΔP 1 /ΔP 0 in the combustion stroke are smaller than a permissible minimum pressure ratio P n and permissible pressure ratio P m of flame quenching, respectively, and at the same time a standardized combustion pressure ratio ΔP 2 /ΔP 0 is equal to or exceeds a permissible pressure ratio P m1 , anda means for increasing the quantity of fuel, including pilot fuel to be injected to a sub-combustion chamber, injected to the cylinder in which flame quenching has occurred upon receipt of the judgment signal of the occurrence of flame quenching. 23. An apparatus for diagnosing and controlling combustion of an internal combustion engine including a gas engine which is constituted so that fuel gas is mixed with air and burned in a combustion chamber, comprising:a cylinder pressure detector for detecting the pressure in the combustion chamber,a crank angle detector for detecting crank rotation angle of the engine,a means for calculating the pressure difference ΔP between detected cylinder pressure P and a reference pressure P b at or before the beginning of compression, including inlet pressure, so that ΔP=P−P b , from cylinder pressure detected by said cylinder pressure detector for a plurality of crank angles in said combustion crank angle range,a means for calculating a standard pressure ratio which is a ratio of sad pressure difference ΔP to a pressure difference ΔP 0 , i.e. ΔP/ΔP 0 , ΔP 0 being the pressure difference between the pressure P 0 at one or a plurality of predetermined crank angles in the compression stroke and said reference pressure P b so that ΔP 0 =P−P b ,a combustion diagnosis apparatus provided with a pressure/analog voltage converting mea ns for outputting at least a part of the result of diagnosis as analog information when diagnosing the condition of combustion in the combustion chamber using said standardized cylinder pressure ratio ΔP/ΔP 0 , anda combustion control apparatus for controlling the combustion condition of the engine by reconverting the analog information outputted from said combustion diagnosis apparatus to pressure information. 24. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 23, wherein the ignition timing of fuel including pilot fuel or quantity of fuel injection is controlled based on the diagnosis result of the pressure information reconverted from said analog information. 25. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 23, wherein the combustion is diagnosed on the basis of each threshold value determined for each diagnosis category information using said standardized pressure ratio ΔP/ΔP 0 in said predetermined crank angle range of combustion. 26. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 23, wherein said threshold values determined for every diagnosis category information are determined so that the level of each threshold decreases stepwise, and information of a different diagnosis category can be judged at a different threshold level. 27. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 23, wherein a pressure detection range is determined near the crank angle of maximum combustion pressure, the threshold for each diagnosis category information is P p0 and P h1 for abnormal Pmax, P h2 for knock, P n for misfire and flame quenching, and the level of each threshold value is decreased in orderly sequence of P n ≦P s1 ≦P sh ≦P h2 ≦P h1 ≦P p0 . 28. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 23, wherein signals of the result of diagnosis transmitted from the combustion diagnosis apparatus to the combustion control apparatus are composed of analog levels, and each analog level for each diagnosis category is determined to decrease stepwise so that the information of a different category is able to be discriminated by the analog level at the combustion control apparatus. 29. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 28, wherein said analog levels for each of diagnosis categories are determined so that the level for transmitting the information of diagnosis category of normal combustion state is positioned in the middle of the levels, the levels for transmitting the information of abnormal maximum cylinder pressure or compression pressure are set to values in a higher level range, and the levels for transmitting information of a misfire, flame quenching, abnormal sensor, and a break in wire are set to values in a lower level range. 30. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 23, wherein, when the range of normal combustion pressure or pressure ratio of each cylinder, the pressure or pressure ratio being between the threshold for knock and that for flame quenching, is transmitted to the combustion control apparatus in an analog level, the pressure or pressure ratio is converted in a stepless analog level signal corresponding with the pressure or pressure ratio and the steplessly controlled analog signal is transmitted to the combustion control apparatus. 31. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 23, wherein a number of analog signal transmission wires corresponding to the number of cylinders are connected between the combustion diagnosis apparatus and combustion control apparatus, the diagnosis result is transmitted in serial ord er in the form of analog levels each determined to decrease stepwise for each diagnosis category, and a diagnosis category is judged or the combustion pressures or pressure ratios corresponding to analog levels is judged based on the corresponding analog level at the combustion control apparatus. 32. An apparatus for diagnosing and controlling combustion of an internal combustion engine including a gas engine which is composed so that fuel gas is mixed with air to be burned in its combustion chamber is provided with a cylinder pressure detector to detect the pressure in the combustion chamber, a crank angle detector to detect the crank rotation angle of the engine, and a displaying apparatus to display a cylinder pressure curve, wherein:a first ring memory for memorizing a cam top crank angle of a reference cam and a cylinder pressure-crank angle curve is provided on a diagnosis apparatus side,a second ring memory for memorizing the cylinder pressure-crank angle curve in a certain crank angle range of each cylinder and a single displaying part are provided on a displaying apparatus side,the first ring memory on the diagnosis side has a means to start a program by an interrupt of a signal from the crank angle detector after detection of the cam top crank angle of the reference cam and write in a cylinder pressure wave form, which indicates a combustion condition, at a certain interval of crank angle to the second ring memory in a determined area corresponding to each cylinder, andpressure-crank angle curves of all cylinders are read out from the determined area of the second ring memory and displayed on said single displaying part with the pressure curves shifted so that each curve does not overlap. 33. An apparatus for diagnosing and controlling combustion of an internal combustion engine as in claim 32, wherein the cylinder pressure-crank angle curves of all cylinders are written into the first ring memory on the diagnosis apparatus side in synchronization with the crank angle at the moment-to-moment detection of the pressure with the cylinder pressure detector, said cylinder pressure-crank angle curves of all cylinders are written in the second ring memory after the cam top crank angle of the next cycle, after the previous cycle of 720° is completed, is detected, and the memorized pressure curves are represented on a single displaying part. 34. A method of diagnosing and controlling combustion of an internal combustion engine including a gas engine which is constituted so that fuel gas is mixed with air and burned in a combustion chamber thereof, comprising:retarding fuel ignition timing of a cylinder of the engine by a certain crank angle to a safety position for combustion through a combustion control apparatus that is operable to control ignition timing of engine fuel and a fuel injection quantity, including pilot fuel, when an abnormality is detected concerning a cylinder pressure detector, which cylinder pressure detector detects the pressure in the combustion chamber of the cylinder and inputs the detected pressure to a combustion diagnosis apparatus; andending said retarding through the combustion control apparatus after said cylinder pressure detector is recovered by replacement or repair thereof. 35. A method of diagnosing combustion of an internal combustion engine including a gas engine which is constituted so that fuel gas is mixed with air and burned in a combustion chamber thereof, comprising:judging a plurality of kinds of abnormality in a predetermined crank angle range in a suction-combustion stroke; andjudging a cylinder pressure detector to be abnormal when an unsatisfactory condition of any one of the plurality of duds of abnormality continues for a predetermined number of cycles. 36. The method of claim 35, wherein said judging a cylinder pressure detector to be abnormal comprises:judging whether or not a pressure detected by the cylinder pressure detector is within a predetermined pressure range du ring the entire crank angle of one cycle,judging whether or not a pressure detected by the cylinder pressure detector is between a permissible maximum inlet pressure and a permissible minimum inlet pressure in the suction stroke,judging whether or not a crank angle at a maximum cylinder pressure is within a crank angle range that corresponds to a combustion range, andjudging whether or not the standard deviation of reference pressures at or before the beginning of compression, including inlet air pressure, of a past plurality of cycles is smaller than a predetermined value.