US4679536A - Engine combustion condition detecting system and method - Google Patents
Engine combustion condition detecting system and method Download PDF
US4679536A
US4679536A US06/781,665 US78166585A US4679536A US 4679536 A US4679536 A US 4679536A US 78166585 A US78166585 A US 78166585A US 4679536 A US4679536 A US 4679536A
US06/781,665
1984-11-28 Priority to JP59-249468 priority Critical
1984-11-28 Priority to JP59249468A priority patent/JPS61128133A/en
1985-09-30 Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
1985-09-30 Assigned to NISSAN MOTOR COMPANY, LIMITED reassignment NISSAN MOTOR COMPANY, LIMITED ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MORITA, TATSUO
1987-07-14 Publication of US4679536A publication Critical patent/US4679536A/en
A fist crank angle sensor 32 generates a reference pulse S0 with each two rotations of the crankshaft of the engine. Accordingly, the pulses S0 are spaced at equal intervals representing 720° of crank angle. The rising edge of each 720° pulse S0 coincides with the top dead center of the compression engine operation stroke of a preselected engine cylinder or precedes the top dead center by a preset crank angle interval, e.g., 70°.
A second crank angle sensor 33 generates a reference pulse S1 each time the engine crankshaft rotates through 180°. Accordingly, the pulses S1 are spaced at equal intervals representing 180° of crank angle. The rising edges of the 180° pulses S1 may coincide with the top dead center of the compression engine operation stroke of each engine cylinder or precede the top dead center by a preset crank angle interval, e.g., 70°. Thus, the 720° pulse S0 is synchronous with one of each four 180° pulses S1.
In the case of an n-cylinder engine, the second crank angle sensor 33 generates pulses spaced at regular crank angle intervals equal to 720°/n, where n represents the number of cylinders.
A third crank angle sensor 34 generates a reference pulse S2 each time the engine crankshaft rotates through 2°. Accordingly, the pulses S2 are spaced at equal intervals representing 2° of crank angle. The duration or width of each pulse S2 is 1° in terms of crank angle, so that the rising and falling edges of the pulses S2 are spaced at equal intervals representing 1° of crank angle. In this way, the reference signal pulses S2 signify each 1° of crank angle.
The N-counter 35 is connected to the crank angle sensors 32 and 34 to receive the 720° pulse S0 and the 180° pulse S1. The N-counter 35 generates a digital signal S3 representative of a number which is incremented by one each time the N-counter 35 receives the rising edge of a 180° pulse S1. The N-counter 35 is reset or cleared to a preset initial value each time it receives the rising edge of a 720° pulse S0. Accordingly, the digital signal S3 periodically assumes each of four different states representing corresponding operation phases of the four engine cylinders. These four states are represented by the numbers "0", "1", "2", and "3" respectively.
The C-counter 37 is connected to the N-counter 35 and the crank angle sensor 34 to receive the digital signal S3 and the 1° signal S2. The C-counter 37 generates a digital signal S4 representative of a number which is incremented by one each time the C-counter 37 receives either of the rising and falling edges of a pulse S2. Accordingly, the number represented by the digital signal S4 is incremented by one each time the engine crankshaft rotates through 1°. The C-counter 37 is reset or cleared to a preset initial value each time the digital signal S3 changes from one state to another.
A memory 42 is connected to the memory 39 to receive the signal S6 representing the peak pressure crank angle θpmax. The memory 42 has four segments to hold corrected peak pressure crank angles θpmax1, θpmax2, θpmax3, and θpmax4 for the engine cylinder #1, #2, #3, and #4 respectively. The memory 42 is connected to the N-counter 35 by way of a holding circuit 56 to receive the signal S3. It should be noted that the holding circuit 56 will be described in detail hereinafter. Each time the signal S3 changes from one state to another, one of the values held in the memory 42 is updated. In cases where the 180° pulses precede the top dead center of the compression strokes by 70°, the memory 42 holds a value equal to the peak pressure crank angle θpmax minus 70. When the signal S3 is "0", the memory segment for the first engine cylinder #1 stores the corrected peak pressure crank angle θpmax1 derived from the peak pressure crank angle θpmax represented by the signal S6. When the signal S3 is "1", the memory segment for the third engine cylinder #3 stores the corrected peak pressure crank angle θpmax3 derived from the peak pressure crank angle θpmax represented by the signal S6. When the signal S3 is "2", the memory segment for the fourth engine cylinder #4 stores the corrected peak pressure crank angle θpmax4 derived from the peak pressure crank angle θpmax represented by the signal S6. When the signal S3 is "3", the memory segment for the second engine cylinder #2 stores the corrected peak pressure crank angle θpmax2 derived from the peak pressure crank angle θpmax represented by the signal S6. The memory 42 generates a digital signal S7 representing the held crank angles θpmax1, θpmax2, θpmax3, and θpmax4.
A spark-timing detector 52 is connected to the crank angle sensors 33 and 34, and to the generator 51 to receive the 180° signal S1, the 1° signal S2, and the spark signal S8. The detector 52 includes a counter which records the total number of rising and falling edges of the 1° signal S2 during the interval between the rising edge of the 180° pulse S1 and the falling edge of the subsequent spark pulse S8. The detector 52 outputs a signal S9 representing spark timing θA relative to the 180° pulse S1, the signal S9 being derived from the total pulse-edge count.
In cases where the rising edge of each 180° pulse S1 precedes the top dead center of the compression stroke by 70°, the spark timing θA is given by the following equation:
θA=70-C,
θc=θA+θpmax
θc=(127θcb+θc)/128
θc=θcb
The reference angle Ref1 is preferably equal to or greater than 20°. The reference ratio Ref2 is preferably equal to or less than 70%.
The microcomputer unit 60 operates in accordance with a program held in the ROM 63. FIGS. 4-6 are flowcharts of segments of this program. The first segment of the program shown in FIG. 4 is executed upon receipt of each 720° pulse S0. The second segment of the program shown in FIG. 5 is executed upon receipt of each 180° pulse S1. The third segment of the program shown in FIG. 6 is executed upon receipt of both edges of each pulse S2. In other words, the first, second, and third segments of the program are executed synchronously with the crank angle signals S0, S1, and S3 respectively.
As shown in FIG. 7, the rising edge of each 720° pulse S0 occurs at a crank angle which precedes the top dead center (TDC) of the compression stroke of the first engine cylinder #1 by 70°.
The segment of the program shown in FIG. 4 starts in response to the rising edge of each 720° pulse S0. As shown in FIG. 4, the program advances to a step 110 in which the number represented by the N-counter 35 is initialized or cleared to "0". After the step 110 is completed, this segment of the program ends and then waits for the next execution cycle.
As shown in FIG. 7, the reference pulses S1 are spaced at equal crank angle intervals, 180° in the case of a four-cylinder engine. The rising edge of each 180° pulse S1 precedes the top dead center of the compression stroke of a corresponding engine cylinder by 70°.
The segment of the program shown in FIG. 5 starts in response to the rising edge of each 180° pulse S1. As shown in FIG. 5, the program advances first to a step 11 in which the number represented by the N-counter 35 is incremented by one.
As shown in FIG. 7, the rising and falling edges of the reference pulses S2 are spaced at equal crank angle intervals of 1°.
As shown in FIG. 6, the program advances first to a step 113 in which the number represented by the POS-counter 65 is incremented by one. Accordingly, the number represented by the POS-counter 65 is incremented by one for each rotation of the engine crankshaft through 1° as shown in FIG. 7.
In a step 121 following the step 120, the value represented by the C-counter 37 is checked to see if it is smaller than a preset value Ref4, e.g., 100. In cases where the reference pulses S1 precede the top dead centers of the compression strokes by 70°, the preset value Ref4 equal to 100 corresponds to a crank angle 30° after the top dead centers. If the value of the C-counter 37 is less than the reference value Ref4, the program advances to a step 122. If the value of the C-counter 37 is equal to or greater than the reference value Ref4, the program advances to a step 123.
In cases where the reference pulses S1 precede the top dead centers of the compression strokes by 70°and the preset value Ref4 is 100, the number represented by the C-counter 37 continues to be periodically incremented by one until the crank angle reaches 30° after the top dead centers as a result of cooperation between the steps 121 and 122.
In this way, while the number in the C-counter 37 increases from 0 to 100 for example, the analog pressure signal is sampled and converted to a corresponding digital signal periodically at crank angles spaced at 1° intervals. These digital pressure values are stored sequentially in the registers respectively. The addresses of the registers represent the crank angles at which the associated stored pressure values are sampled.
A first correction calculator 204 is connected to the combustion condition detector 200 to receive the signal S7 representing the peak pressure crank angles θpmax1-4. Each time the engine crankshaft rotates through 180°, the calculator 204 determines a correction factor ΔθA1 for spark timing. It should be noted that the reference pulses S1 may be used to trigger this periodic determination of the correction factor ΔθA1. An output signal S24 from the calculator 204 represents the determined correction factor ΔθA1.
Specifically, the calculator 204 first determines whether or not the peak pressure crank angle θpmax follows a preset target timing Ref7. If the peak pressure crank angle θpmax trails the target timing Ref7, the calculator 204 sets the correction factor ΔθA1 to a value that will advance the actual spark timing. If the peak pressure crank angle θpmax leads the target timing Ref7, the calculator 204 sets the correction factor ΔθA1 to a value that will retard the actual spark timing. This operation tends to hold the peak pressure crank angle θpmax at essentially the target timing Ref7, since the peak pressure crank angle θpmax depends on the actual spark timing. It should be noted that the target timing Ref7 trails the top dead center of the compression stroke by a preset crank angle interval in the range of 10°-20°.
ΔθA1=ΔθA(preceding)+a
ΔθA1=ΔθA(preceding)-a
A second correction calculator 205 is connected to the combustion condition detector 200 to receive the signal S15 indicating whether or not the detected peak pressure crank angle is acceptable. In cases where the detected peak pressure crank angle is unacceptable, each time the engine crankshaft rotates through 180°, the calculator 205 derives a correction factor ΔθA2 for spark timing by referring to the following equation:
ΔθA2=ΔθA(preceding)+b
where b is a preset constant inducing advance of the actual spark timing. It should be noted that unacceptable peak pressure crank angles generally result from excessive retardation of the spark timing. The constant b is preferably in the range of 1°-10° in terms of crank angle. It should be noted that the reference pulses S1 may be used to trigger this periodic determination of the correction factor ΔθA2. An output signal S25 from the calculator 205 represents the derived correction factor ΔθA2.
θA=θA0+ΔθA
The control unit 210 operates in accordance with a program held in the ROM 212. The program is executed periodically in synchronism with the reference pulses S1 from the crank angle sensor 33, which are conducted to the I/O circuit 211 through a connection between these elements 33 and 211. Accordingly, the program is executed each time the engine crankshaft rotates through 180° in the case of a four-cylinder engine.
α=α+ΔαR
α=α-ΔαL
A second correction calculator 303 is connected to the combustion condition detector 200 to receive the signal S15 indicating whether or not the detected peak pressure crank angle is acceptable. Each time the engine crankshaft rotates through 180°, the calculator 303 derives a new correction factor α for the air-to-fuel ratio on the basis of whether or not the detected peak pressure crank angle is acceptable. It should be noted that the reference pulses S1 may be used to trigger this periodic derivation of the correction factor α. An output signal S33 from the calculator 303 represents the derived correction factor α.
In the case where the signal S15 changes from "0" to "1", that is, in the case where the signal S15 changes to indicate that the detected peak pressure crank angle is unacceptable, the calculator 303 first initializes the correction factor α to a value equal to the final correction factor α given by the calculator 302. It should be noted that the calculator 303 is connected to the calculator 302 to receive the signal S32 representing the correction factor α derived by the calculator 302. If this initial value is greater than 1.0, the calculator 303 then derives the correction factor α by referring to the equation below each time the engine crankshaft rotates through 180°:
α=α(preceding)-c
where c is a preset positive constant. This periodic derivation of the correction factor α continues until the signal S15 returns from "1" to "0", that is, unitl the signal S15 changes to indicate that the detected peak pressure crank angle is acceptable. If the initial value is not greater than 1.0, the calculator 302 then derives the correction factor α by referring to the following equation each time the engine crankshaft rotates through 180°:
α=α(preceding)+d
Ti=αTp+Ts
The control unit 310 operates in accordance with a program held in the ROM 312. The program is executed in synchronism with the reference pulses S1. Accordingly, in the case of a four-cylinder engine, the program is executed each time the engine crankshaft rotates through 180°.
α=α(preceding)+Δα
1. A system for an engine including a combustion chamber in which combustion is induced periodically by generating a spark, the system comprising:
(a) means for sensing pressure within the combustion chamber;
(b) means for detecting a timing at which the sensed pressure peaks;
(c) means for measuring an interval between an occurrence of a spark generation and the timing of the pressure peak;
(e) means for, in accordance with a length of the presently measured interval, selectively storing the presently detected timing of the peak pressure in the memory in place of data held previously in the memory or ignoring the presently detected timing of the pressure peak so as to allow the memory to continue to hold the previously detected timing of the pressure peak, comprising:
(1) means for deriving a mean value of the periodically measured intervals;
(2) means for comparing the presently measured interval to a reference value which is related to the mean value of the intervals;
(3) means for, when the presently measured interval is greater than the reference value, storing the presently detected timing of the pressure peak in the memory; and
(4) means for, when the presently measured interval is not greater than the reference value, ignoring the presently detected timing of the pressure peak;
(f) means for outputting a signal representing the detected timing currently held in the memory.
2. The system of claim 1, further comprising means for controlling the moment of spark generation in accordance with the timing of the pressure peak represented by the output signal.
7. A system for an engine including a crankshaft and a combustion chamber in which combustion is induced periodically with respect to rotation of the crankshaft, the system comprising:
(b) means for periodically detecting an angle of the crankshaft at which the sensed pressure peaks;
(c) means for deriving a mean value of the periodically detected peak pressure crankshaft angles;
(d) means for comparing the presently detected peak pressure crankshaft angle to a reference value which is related to the mean value;
(f) means for, in accordance with the comparison between the presently detected peak pressure crankshaft angle and the reference value, selectively storing the presently detected peak pressure crankshaft angle in the memory in place of data held previously in the memory or ignoring the presently detected peak pressure crankshaft angle so as to allow the memory to continue to hold the previously detected peak pressure crankshaft angle; and
(g) means for outputting a signal representing the detected peak pressure crankshaft angle currently held in the memory.
8. The system of claim 7, further comprising means for controlling the moment of spark generation in accordance with the timing of the pressure peak represented by the output signal.
US06/781,665 1984-11-28 1985-09-30 Engine combustion condition detecting system and method Expired - Fee Related US4679536A (en)
JP59-249468 1984-11-28
JP59249468A JPS61128133A (en) 1984-11-28 1984-11-28 Apparatus for detecting combustion state of internal combustion engine
US4679536A true US4679536A (en) 1987-07-14
ID=17193403
US06/781,665 Expired - Fee Related US4679536A (en) 1984-11-28 1985-09-30 Engine combustion condition detecting system and method
US (1) US4679536A (en)
EP (1) EP0183239A2 (en)
JP (1) JPS61128133A (en)
WO2001059281A1 (en) * 2000-02-12 2001-08-16 Mtu Friedrichshafen Gmbh System for regulating an internal combustion engine
JP2935237B2 (en) * 1988-10-11 1999-08-16 本田技研工業株式会社 Knock control system for an internal combustion engine
1984-11-28 JP JP59249468A patent/JPS61128133A/en active Pending
1985-09-30 US US06/781,665 patent/US4679536A/en not_active Expired - Fee Related
1985-11-27 EP EP19850115018 patent/EP0183239A2/en not_active Withdrawn
US6837214B2 (en) 2000-02-12 2005-01-04 Mtu Friedrichshafen Gmbh System for regulating an internal combustion engine
JPS61128133A (en) 1986-06-16
EP0183239A2 (en) 1986-06-04
DE19680104C2 (en) 2001-04-05 Method and system for controlling internal combustion engines
US7113861B2 (en) 2006-09-26 System and method for diagnosing and calibrating internal combustion engines
DE4138765C2 (en) 2002-01-24 Method and device for determining an uneven running value of an internal combustion engine
JP4033138B2 (en) 2008-01-16 Combustion pressure signal processor
JP3252390B2 (en) 2002-02-04 How to perform a sequential injection process
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:MORITA, TATSUO;REEL/FRAME:004463/0680
US4679536A - Engine combustion condition detecting system and method - Google Patents
Engine combustion condition detecting system and method Download PDF
US4679536A
US4679536A US06/781,665 US78166585A US4679536A US 4679536 A US4679536 A US 4679536A US 78166585 A US78166585 A US 78166585A US 4679536 A US4679536 A US 4679536A
US06/781,665
1984-11-28 Priority to JP59-249468 priority Critical
1984-11-28 Priority to JP59249468A priority patent/JPS61128133A/en
1985-09-30 Application filed by Nissan Motor Co Ltd filed Critical Nissan Motor Co Ltd
1985-09-30 Assigned to NISSAN MOTOR COMPANY, LIMITED reassignment NISSAN MOTOR COMPANY, LIMITED ASSIGNMENT OF ASSIGNORS INTEREST. Assignors: MORITA, TATSUO
1987-07-14 Publication of US4679536A publication Critical patent/US4679536A/en
A fist crank angle sensor 32 generates a reference pulse S0 with each two rotations of the crankshaft of the engine. Accordingly, the pulses S0 are spaced at equal intervals representing 720° of crank angle. The rising edge of each 720° pulse S0 coincides with the top dead center of the compression engine operation stroke of a preselected engine cylinder or precedes the top dead center by a preset crank angle interval, e.g., 70°.
A second crank angle sensor 33 generates a reference pulse S1 each time the engine crankshaft rotates through 180°. Accordingly, the pulses S1 are spaced at equal intervals representing 180° of crank angle. The rising edges of the 180° pulses S1 may coincide with the top dead center of the compression engine operation stroke of each engine cylinder or precede the top dead center by a preset crank angle interval, e.g., 70°. Thus, the 720° pulse S0 is synchronous with one of each four 180° pulses S1.
In the case of an n-cylinder engine, the second crank angle sensor 33 generates pulses spaced at regular crank angle intervals equal to 720°/n, where n represents the number of cylinders.
A third crank angle sensor 34 generates a reference pulse S2 each time the engine crankshaft rotates through 2°. Accordingly, the pulses S2 are spaced at equal intervals representing 2° of crank angle. The duration or width of each pulse S2 is 1° in terms of crank angle, so that the rising and falling edges of the pulses S2 are spaced at equal intervals representing 1° of crank angle. In this way, the reference signal pulses S2 signify each 1° of crank angle.
The N-counter 35 is connected to the crank angle sensors 32 and 34 to receive the 720° pulse S0 and the 180° pulse S1. The N-counter 35 generates a digital signal S3 representative of a number which is incremented by one each time the N-counter 35 receives the rising edge of a 180° pulse S1. The N-counter 35 is reset or cleared to a preset initial value each time it receives the rising edge of a 720° pulse S0. Accordingly, the digital signal S3 periodically assumes each of four different states representing corresponding operation phases of the four engine cylinders. These four states are represented by the numbers "0", "1", "2", and "3" respectively.
The C-counter 37 is connected to the N-counter 35 and the crank angle sensor 34 to receive the digital signal S3 and the 1° signal S2. The C-counter 37 generates a digital signal S4 representative of a number which is incremented by one each time the C-counter 37 receives either of the rising and falling edges of a pulse S2. Accordingly, the number represented by the digital signal S4 is incremented by one each time the engine crankshaft rotates through 1°. The C-counter 37 is reset or cleared to a preset initial value each time the digital signal S3 changes from one state to another.
A memory 42 is connected to the memory 39 to receive the signal S6 representing the peak pressure crank angle θpmax. The memory 42 has four segments to hold corrected peak pressure crank angles θpmax1, θpmax2, θpmax3, and θpmax4 for the engine cylinder #1, #2, #3, and #4 respectively. The memory 42 is connected to the N-counter 35 by way of a holding circuit 56 to receive the signal S3. It should be noted that the holding circuit 56 will be described in detail hereinafter. Each time the signal S3 changes from one state to another, one of the values held in the memory 42 is updated. In cases where the 180° pulses precede the top dead center of the compression strokes by 70°, the memory 42 holds a value equal to the peak pressure crank angle θpmax minus 70. When the signal S3 is "0", the memory segment for the first engine cylinder #1 stores the corrected peak pressure crank angle θpmax1 derived from the peak pressure crank angle θpmax represented by the signal S6. When the signal S3 is "1", the memory segment for the third engine cylinder #3 stores the corrected peak pressure crank angle θpmax3 derived from the peak pressure crank angle θpmax represented by the signal S6. When the signal S3 is "2", the memory segment for the fourth engine cylinder #4 stores the corrected peak pressure crank angle θpmax4 derived from the peak pressure crank angle θpmax represented by the signal S6. When the signal S3 is "3", the memory segment for the second engine cylinder #2 stores the corrected peak pressure crank angle θpmax2 derived from the peak pressure crank angle θpmax represented by the signal S6. The memory 42 generates a digital signal S7 representing the held crank angles θpmax1, θpmax2, θpmax3, and θpmax4.
A spark-timing detector 52 is connected to the crank angle sensors 33 and 34, and to the generator 51 to receive the 180° signal S1, the 1° signal S2, and the spark signal S8. The detector 52 includes a counter which records the total number of rising and falling edges of the 1° signal S2 during the interval between the rising edge of the 180° pulse S1 and the falling edge of the subsequent spark pulse S8. The detector 52 outputs a signal S9 representing spark timing θA relative to the 180° pulse S1, the signal S9 being derived from the total pulse-edge count.
In cases where the rising edge of each 180° pulse S1 precedes the top dead center of the compression stroke by 70°, the spark timing θA is given by the following equation:
θA=70-C,
θc=θA+θpmax
θc=(127θcb+θc)/128
θc=θcb
The reference angle Ref1 is preferably equal to or greater than 20°. The reference ratio Ref2 is preferably equal to or less than 70%.
The microcomputer unit 60 operates in accordance with a program held in the ROM 63. FIGS. 4-6 are flowcharts of segments of this program. The first segment of the program shown in FIG. 4 is executed upon receipt of each 720° pulse S0. The second segment of the program shown in FIG. 5 is executed upon receipt of each 180° pulse S1. The third segment of the program shown in FIG. 6 is executed upon receipt of both edges of each pulse S2. In other words, the first, second, and third segments of the program are executed synchronously with the crank angle signals S0, S1, and S3 respectively.
As shown in FIG. 7, the rising edge of each 720° pulse S0 occurs at a crank angle which precedes the top dead center (TDC) of the compression stroke of the first engine cylinder #1 by 70°.
The segment of the program shown in FIG. 4 starts in response to the rising edge of each 720° pulse S0. As shown in FIG. 4, the program advances to a step 110 in which the number represented by the N-counter 35 is initialized or cleared to "0". After the step 110 is completed, this segment of the program ends and then waits for the next execution cycle.
As shown in FIG. 7, the reference pulses S1 are spaced at equal crank angle intervals, 180° in the case of a four-cylinder engine. The rising edge of each 180° pulse S1 precedes the top dead center of the compression stroke of a corresponding engine cylinder by 70°.
The segment of the program shown in FIG. 5 starts in response to the rising edge of each 180° pulse S1. As shown in FIG. 5, the program advances first to a step 11 in which the number represented by the N-counter 35 is incremented by one.
As shown in FIG. 7, the rising and falling edges of the reference pulses S2 are spaced at equal crank angle intervals of 1°.
As shown in FIG. 6, the program advances first to a step 113 in which the number represented by the POS-counter 65 is incremented by one. Accordingly, the number represented by the POS-counter 65 is incremented by one for each rotation of the engine crankshaft through 1° as shown in FIG. 7.
In a step 121 following the step 120, the value represented by the C-counter 37 is checked to see if it is smaller than a preset value Ref4, e.g., 100. In cases where the reference pulses S1 precede the top dead centers of the compression strokes by 70°, the preset value Ref4 equal to 100 corresponds to a crank angle 30° after the top dead centers. If the value of the C-counter 37 is less than the reference value Ref4, the program advances to a step 122. If the value of the C-counter 37 is equal to or greater than the reference value Ref4, the program advances to a step 123.
In cases where the reference pulses S1 precede the top dead centers of the compression strokes by 70°and the preset value Ref4 is 100, the number represented by the C-counter 37 continues to be periodically incremented by one until the crank angle reaches 30° after the top dead centers as a result of cooperation between the steps 121 and 122.
In this way, while the number in the C-counter 37 increases from 0 to 100 for example, the analog pressure signal is sampled and converted to a corresponding digital signal periodically at crank angles spaced at 1° intervals. These digital pressure values are stored sequentially in the registers respec
tively. The addresses of the registers represent the crank angles at which the associated stored pressure values are sampled.
A first correction calculator 204 is connected to the combustion condition detector 200 to receive the signal S7 representing the peak pressure crank angles θpmax1-4. Each time the engine crankshaft rotates through 180°, the calculator 204 determines a correction factor ΔθA1 for spark timing. It should be noted that the reference pulses S1 may be used to trigger this periodic determination of the correction factor ΔθA1. An output signal S24 from the calculator 204 represents the determined correction factor ΔθA1.
Specifically, the calculator 204 first determines whether or not the peak pressure crank angle θpmax follows a preset target timing Ref7. If the peak pressure crank angle θpmax trails the target timing Ref7, the calculator 204 sets the correction factor ΔθA1 to a value that will advance the actual spark timing. If the peak pressure crank angle θpmax leads the target timing Ref7, the calculator 204 sets the correction factor ΔθA1 to a value that will retard the actual spark timing. This operation tends to hold the peak pressure crank angle θpmax at essentially the target timing Ref7, since the peak pressure crank angle θpmax depends on the actual spark timing. It should be noted that the target timing Ref7 trails the top dead center of the compression stroke by a preset crank angle interval in the range of 10°-20°.
ΔθA1=ΔθA(preceding)+a
ΔθA1=ΔθA(preceding)-a
A second correction calculator 205 is connected to the combustion condition detector 200 to receive the signal S15 indicating whether or not the detected peak pressure crank angle is acceptable. In cases where the detected peak pressure crank angle is unacceptable, each time the engine crankshaft rotates through 180°, the calculator 205 derives a correction factor ΔθA2 for spark timing by referring to the following equation:
ΔθA2=ΔθA(preceding)+b
where b is a preset constant inducing advance of the actual spark timing. It should be noted that unacceptable peak pressure crank angles generally result from excessive retardation of the spark timing. The constant b is preferably in the range of 1°-10° in terms of crank angle. It should be noted that the reference pulses S1 may be used to trigger this periodic determination of the correction factor ΔθA2. An output signal S25 from the calculator 205 represents the derived correction factor ΔθA2.
θA=θA0+ΔθA
The control unit 210 operates in accordance with a program held in the ROM 212. The program is executed periodically in synchronism with the reference pulses S1 from the crank angle sensor 33, which are conducted to the I/O circuit 211 through a connection between these elements 33 and 211. Accordingly, the program is executed each time the engine crankshaft rotates through 180° in the case of a four-cylinder engine.
α=α+ΔαR
α=α-ΔαL
A second correction calculator 303 is connected to the combustion condition detector 200 to receive the signal S15 indicating whether or not the detected peak pressure crank angle is acceptable. Each time the engine crankshaft rotates through 180°, the calculator 303 derives a new correction factor α for the air-to-fuel ratio on the basis of whether or not the detected peak pressure crank angle is acceptable. It should be noted that the reference pulses S1 may be used to trigger this periodic derivation of the correction factor α. An output signal S33 from the calculator 303 represents the derived correction factor α.
In the case where the signal S15 changes from "0" to "1", that is, in the case where the signal S15 changes to indicate that the detected peak pressure crank angle is unacceptable, the calculator 303 first initializes the correction factor α to a value equal to the final correction factor α given by the calculator 302. It should be noted that the calculator 303 is connected to the calculator 302 to receive the signal S32 representing the correction factor α derived by the calculator 302. If this initial value is greater than 1.0, the calculator 303 then derives the correction factor α by referring to the equation below each time the engine crankshaft rotates through 180°:
α=α(preceding)-c
where c is a preset positive constant. This periodic derivation of the correction factor α continues until the signal S15 returns from "1" to "0", that is, unitl the signal S15 changes to indicate that the detected peak pressure crank angle is acceptable. If the initial value is not greater than 1.0, the calculator 302 then derives the correction factor α by referring to the following equation each time the engine crankshaft rotates through 180°:
α=α(preceding)+d
Ti=αTp+Ts
The control unit 310 operates in accordance with a program held in the ROM 312. The program is executed in synchronism with the reference pulses S1. Accordingly, in the case of a four-cylinder engine, the program is executed each time the engine crankshaft rotates through 180°.
α=α(preceding)+Δα
1. A system for an engine including a combustion chamber in which combustion is induced periodically by generating a spark, the system comprising:
(a) means for sensing pressure within the combustion chamber;
(b) means for detecting a timing at which the sensed pressure peaks;
(c) means for measuring an interval between an occurrence of a spark generation and the timing of the pressure peak;
(e) means for, in accordance with a length of the presently measured interval, selectively storing the presently detected timing of the peak pressure in the memory in place of data held previously in the memory or ignoring the presently detected timing of the pressure peak so as to allow the memory to continue to hold the previously detected timing of the pressure peak, comprising:
(1) means for deriving a mean value of the periodically measured intervals;
(2) means for comparing the presently measured interval to a reference value which is related to the mean value of the intervals;
(3) means for, when the presently measured interval is greater than the reference value, storing the presently detected timing of the pressure peak in the memory; and
(4) means for, when the presently measured interval is not greater than the reference value, ignoring the presently detected timing of the pressure peak;
(f) means for outputting a signal representing the detected timing currently held in the memory.
2. The system of claim 1, further comprising means for controlling the moment of spark generation in accordance with the timing of the pressure peak represented by the output signal.
7. A system for an engine including a crankshaft and a combustion chamber in which combustion is induced periodically with respect to rotation of the crankshaft, the system comprising:
(b) means for periodically detecting an angle of the crankshaft at which the sensed pressure peaks;
(c) means for deriving a mean value of the periodically detected peak pressure crankshaft angles;
(d) means for comparing the presently detected peak pressure crankshaft angle to a reference value which is related to the mean value;
(f) means for, in accordance with the comparison between the presently detected peak pressure crankshaft angle and the reference value, selectively storing the presently detected peak pressure crankshaft angle in the memory in place of data held previously in the memory or ignoring the presently detected peak pressure crankshaft angle so as to allow the memory to continue to hold the previously detected peak pressure crankshaft angle; and
(g) means for outputting a signal representing the detected peak pressure crankshaft angle currently held in the memory.
8. The system of claim 7, further comprising means for controlling the moment of spark generation in accordance with the timing of the pressure peak represented by the output signal.
US06/781,665 1984-11-28 1985-09-30 Engine combustion condition detecting system and method Expired - Fee Related US4679536A (en)
JP59-249468 1984-11-28
JP59249468A JPS61128133A (en) 1984-11-28 1984-11-28 Apparatus for detecting combustion state of internal combustion engine
US4679536A true US4679536A (en) 1987-07-14
ID=17193403
US06/781,665 Expired - Fee Related US4679536A (en) 1984-11-28 1985-09-30 Engine combustion condition detecting system and method
US (1) US4679536A (en)
EP (1) EP0183239A2 (en)
JP (1) JPS61128133A (en)
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JP2935237B2 (en) * 1988-10-11 1999-08-16 本田技研工業株式会社 Knock control system for an internal combustion engine
1984-11-28 JP JP59249468A patent/JPS61128133A/en active Pending
1985-09-30 US US06/781,665 patent/US4679536A/en not_active Expired - Fee Related
1985-11-27 EP EP19850115018 patent/EP0183239A2/en not_active Withdrawn
US6837214B2 (en) 2000-02-12 2005-01-04 Mtu Friedrichshafen Gmbh System for regulating an internal combustion engine
JPS61128133A (en) 1986-06-16
EP0183239A2 (en) 1986-06-04
DE19680104C2 (en) 2001-04-05 Method and system for controlling internal combustion engines
US7113861B2 (en) 2006-09-26 System and method for diagnosing and calibrating internal combustion engines
DE4138765C2 (en) 2002-01-24 Method and device for determining an uneven running value of an internal combustion engine
JP4033138B2 (en) 2008-01-16 Combustion pressure signal processor
JP3252390B2 (en) 2002-02-04 How to perform a sequential injection process
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