JP2002089345A - Misfire detection device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the precision of misfire detection of an engine. SOLUTION: This flameout detection device is furnished with a rotating angle detection means 17 to detect a rotating angle of an output shaft of the engine, a learning means 37 to learn tolerance by finding the to tolerance of rotating angular speed, a rotating angle correction means 37 to correct the rotating angle detected by the rotating angle detection means, a feedback control means 37 to detect an air-fuel ratio of combustion gas of the engine and to feedback-control it in accordance with a feedback correction value found by the air-fuel ratio and a tolerance learning prohibiting means 37 to prohibit tolerance learning, and it prohibits learning of the tolerance until specified time passes after the feedback correction value is reset while the feedback correction value is stuck to a specified upper limit value or a specified lower limit value in the middle of controlling it by the feedback control means 37.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine misfire detection device for detecting a misfire occurring in an engine.

[0002]

2. Description of the Related Art When a misfire occurs in an engine, the rotational angular velocity of a crankshaft, which is the output shaft of the engine, usually decreases. Therefore, the rotational angular velocity of the crankshaft has been monitored to determine whether a misfire has occurred in the engine. It has been done to detect if. FIG. 6 shows a crankshaft rotation angle detection device 1 in a four-cylinder gasoline engine. The rotation angle detection device 1 includes a rotor plate 3 attached to a crankshaft 2;
A predetermined number (four in the figure) of teeth 4 which are detection portions provided on the outer periphery of the rotor plate 3;
And a rotation angle sensor 5 provided in close proximity to the crankshaft 2. The state of the rotation angular velocity of the crankshaft 1 is monitored by the teeth 4 traversing the rotation angle sensor 3 as the crankshaft 2 rotates. Detects whether a misfire has occurred in the engine. During the misfire detection operation, the engine detects the tolerance of the rotational angle between the teeth 3 of the rotor plate 2 and corrects the rotational angular velocity of the crankshaft 1 based on the tolerance to determine misfire. Is prevented from being erroneously determined to have been misfired despite being normally ignited.

However, even if the above-mentioned tolerance is learned at the time of misfire detection as described above, the accuracy of misfire detection cannot be improved unless the learned tolerance itself has high accuracy. Therefore, in order to increase the accuracy of the tolerance, attempts have been made to prohibit learning of the tolerance when certain conditions are satisfied.
There is one disclosed in Japanese Patent Publication No. 166042. This is because the engine is misfired when the air-fuel ratio feedback correction value output by the oxygen sensor that detects the air-fuel ratio rich / lean based on the oxygen concentration of the combustion gas sticks to the lean side for a predetermined time. The learning of the tolerance during that period is prohibited, and the accuracy of misfire detection is improved.

[0004]

However, in the engine misfire detection device disclosed in Japanese Patent Application Laid-Open No. 9-166042, the air-fuel ratio feedback correction value is stuck to the lean side as shown in FIG. However, if a misfire has occurred, that is,
The tolerance is also learned when the air-fuel ratio feedback correction value is reset, for example, when the negative pressure cut control of the pressure regulator is turned on or off at the time of switching off, so that the accuracy of misfire detection deteriorates.

The present invention has been made in view of the above, and it is an object of the present invention to provide an engine misfire detecting device capable of improving the accuracy of detecting a misfire occurring in an engine.

[0006]

SUMMARY OF THE INVENTION The present invention comprises: a rotation angle detecting means for detecting a rotation angle of an output shaft of an engine; a learning means for obtaining a tolerance of the rotation angular velocity and learning the tolerance;
A rotation angle correction unit that corrects the rotation angle detected by the rotation angle detection unit, based on the tolerance learned by the learning unit, and an air-fuel ratio of combustion gas of the engine,
Feedback control means for performing feedback control based on the feedback correction value obtained from the air-fuel ratio; and during the control by the feedback control means, while the feedback correction value sticks to a predetermined upper limit or lower limit, and And a learning prohibiting unit for prohibiting the learning of the tolerance until a predetermined time elapses after the correction value is reset.

Preferably, the predetermined time during which the tolerance learning is inhibited is determined based on a time required for the correction value to substantially converge after the feedback correction value is reset, and the tolerance learning is inhibited. The predetermined time can be changed according to the engine speed.

In such a configuration, tolerance learning is prohibited for a predetermined time after the feedback correction value is reset, so that there is no possibility of erroneous learning of the tolerance.
The accuracy of misfire detection can be improved.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a four-cylinder gasoline engine 11 having a misfire detection device according to an embodiment of the present invention.
3 is a schematic configuration diagram of the engine 11 of FIG.
Only the cylinder is shown. In this case, the engine 11 has four cylinders 12 and 180 ° CA (crank angle).
Each time, ignition is set in the order of the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder.

A piston 13 is accommodated in each of the cylinders 12, and a combustion chamber 14 is formed above the piston 13. A rotor plate 15 is attached to a crankshaft (not shown) of the piston 13, and a required number (four in this case) is provided on the outer periphery of the rotor plate 15.
Are provided. Further, the cylinder 12 includes:
A rotation angle sensor 17 for outputting a rotation angle signal of the engine 11 is provided at a position close to the teeth 16, and a cam angle sensor 18 for outputting a cylinder identification signal and a water temperature for detecting a coolant temperature of the engine 11. A sensor 19 is provided at an appropriate position.

An intake pipe 2 is provided in a combustion chamber 14 of each cylinder 12.
0 and the exhaust pipe 21 communicate with each other, and an air cleaner 22, an air flow sensor 23, a throttle valve 24, a surge tank 25, and an injector 27 are attached to the intake pipe 20 in this order from the upstream side. The injector 27 is connected to a fuel pump 30 in a fuel tank 29 via a fuel supply pipe 28, and a pressure regulator 31 is provided in the fuel supply pipe 28. Also,
A canister 32 is provided between the fuel tank 29 and the intake pipe 20 to temporarily store fuel gas evaporated from the fuel tank 29, and to inhale the fuel gas into the intake pipe 20 when the engine 11 starts. It is made to let.
Further, the throttle valve 24 is bypassed by a bypass pipe 33, and an idle speed control valve (ISC valve) 34 is interposed in the bypass pipe 33.
The idle speed is controlled by adjusting the amount of bypass air flowing through the engine 3. On the other hand, the exhaust pipe 21 has a catalytic converter 3 for purifying the exhaust bus.
5 is provided, and an oxygen sensor 36 is provided upstream of the catalytic converter 35. The detection signals from the various sensors described above are input to an electronic control unit 37. The electronic control unit 37 includes a tolerance learning function, a rotation angle correction function, and an air-fuel ratio feedback control function, which will be described later. It has various functions such as a tolerance learning prohibition function.

Next, the misfire detection operation by the misfire detection device according to the embodiment of the present invention will be described with reference to the flowcharts of FIGS. 2 and 3 and FIG.

First, in step 101, the engine 11 is controlled based on a detection signal from the rotation angle sensor 17.
And the amount of intake air (Ga) is read based on the detection signal from the air flow sensor 23. The electronic control unit 37 calculates a basic fuel injection amount (Te) based on the read rotation speed (Ne) and the intake air amount (Ga) of the engine 11 (step 10).
2) Further, based on the calculation result, the fuel correction increase (Cad
d) is calculated (step 103). Then, in step 104, it is determined whether a fuel feedback condition is satisfied based on operating conditions such as the rotation speed (Ne) of the engine 11 and the intake air amount (Ga).

If the electronic control unit 37 determines that the fuel feedback condition is satisfied, it reads the air-fuel ratio based on the output of the oxygen sensor 36 in step 105. If the air-fuel ratio is equal to or less than the predetermined value, it is determined that the engine is lean, and the process proceeds to step 107. If the air-fuel ratio is not equal to or less than the predetermined value, it is determined that the air-fuel ratio is rich, and the process proceeds to step 108 (step 106). In step 107, a predetermined value α is added to the previous feedback correction value (Cfb).
Is added to update the feedback correction value (Cfb). In step 108, the predetermined value α is subtracted from the previous feedback correction value (Cfb) to update the feedback correction value (Cfb).

On the other hand, if it is determined in step 104 that the fuel feedback condition is not satisfied, in step 109, the feedback correction value (Cfb) is reset to 0. (Tcfb) is reset to 0.

Next, in step 111, the pressure regulator negative pressure cut condition, specifically, for example,
The water temperature is equal to or higher than a predetermined temperature, the intake air temperature is equal to or higher than a predetermined temperature, and a predetermined time has not elapsed since the engine was started (for example, within 120 seconds). It is determined whether or not the state changes to a state not satisfying the condition (1). If it is determined that the state has not changed to satisfy the pressure regulator negative pressure cut condition (that is, YES), the learning prohibition timer (Tcfb) is reset to 0 in step 112, and then the process proceeds to step 113. If not (ie, NO), the process skips step 112 and proceeds to step 113.

In step 113, it is determined whether or not the state has changed from the state having the purge execution condition to the state not having the purge execution condition or from the state not having the condition to the purge execution condition. If it is determined that it has changed (that is, YES), at step 114, the learning prohibition timer (Tcf
After b) is reset to 0, the process proceeds to step 115,
If it is determined that there is no change (that is, NO), step 114 is skipped and the process proceeds to step 115. In step 115, the previous learning inhibition timer (Tc
The learning inhibition timer (Tcfb) is updated by adding 1 to fb).

Then, in step 116, the final value is obtained by the formula Ti = (Cfb + Cadd) × Te based on the feedback correction value (Cfb), the fuel correction increase (Cadd), and the basic fuel injection amount (Te) obtained in the above steps. The fuel injection amount (Ti) is calculated, and the fuel of the final fuel injection amount (Ti) is injected from the injector 27 into the combustion chamber 14.

Next, at step 118, it is determined whether a misfire detection condition is satisfied. Specifically, a predetermined time (for example, 0 to 5 seconds) has elapsed after the start of the engine 11, and a predetermined value (for example,
-10 ° C) or higher, and the water temperature is a predetermined value (for example,-
10 ° C.) or more, and a predetermined time after the shift (for example,
(1 second) has elapsed, a predetermined time (for example, 1 second) has elapsed after returning from fuel cut, and a predetermined time (for example, 1 second) for determination after acceleration / deceleration has elapsed. That a predetermined time (for example, one second) has elapsed after the load change, that the vehicle speed is greater than 0 and that the brake is not operating, and that the rotation speed of the engine 11 is within a predetermined range (for example, 500 to 4500 rpm). And all the conditions that the load of the engine 11 (for example, intake air charging efficiency obtained by dividing the intake air amount by the engine speed) is within a predetermined range (for example, 0.15 to 1.0) are satisfied. If the misfire detection condition is satisfied, it is determined that the misfire detection condition is satisfied. If it is determined that all of the above-described misfire detection conditions are satisfied, the process proceeds to step 119; otherwise, steps 119 and 12 are performed.
The process skips 0, 121, and 122 and proceeds to step 123.

In step 119, the learning inhibition timer Tc
It is determined whether or not fb exceeds a predetermined value β.
If it is determined that the time has exceeded the limit, the process proceeds to step 120;
Skip to step 122 and proceed to step 123. In this case, the predetermined value β is preferably determined based on a time t required for the correction value to substantially converge after the feedback correction value (Cfb) is reset, as shown in FIG. Alternatively, it may be changed according to the rotation speed of the engine 11.

Thereafter, in step 120, it is determined whether or not the feedback correction value is equal to the upper limit value or the lower limit value. If they are not equal, the process proceeds to step 121, and if they are equal, steps 121 and 122 are performed. Skip to step 123.

In step 121, it is determined whether or not the tolerance learning condition of the rotor plate 15 is satisfied. Specifically, a predetermined time (for example, 19 seconds) has elapsed after the start of the engine 11, a predetermined time (for example, 1 second) has elapsed after the starter is turned on,
A predetermined time (for example, one second) has elapsed after the brake operation, a predetermined time (for example, one second) has elapsed after the load change, and a predetermined time (for example, one second) after the shift.
Has elapsed, that a predetermined time (for example, one second) has elapsed after returning from fuel cut, that a predetermined time (for example, one second) has elapsed after acceleration / deceleration, and that the oxygen sensor 36 has been activated. The state is determined to be in a state, the cooling water temperature is equal to or higher than a predetermined value (for example, 70 ° C.), the rotation fluctuation of the engine 11 is equal to or lower than a predetermined value, and the MIL is not lit. , The engine 11
(For example, the intake air charging efficiency obtained by dividing the intake air amount by the engine speed) is within a predetermined range (for example, 0.15 to 1.
0), that a predetermined time (for example, 0.5 seconds) has elapsed since the EGR monitor was activated, that the number of rough road determinations is less than or equal to a predetermined value (for example, 4), and that intermittent fire has been detected. That no misfires have been detected,
The output signal of the oxygen sensor 36 is rich in the fuel feedback control or in the fuel enrichment zone, the deviation of the fuel system is within a predetermined range, and the reversal cycle of the oxygen sensor 36 is in a predetermined range (for example, , 0.
2 to 3 seconds), and when all the conditions that the failure pending code of the oxygen sensor 36 does not stand are satisfied, it is determined that the tolerance learning condition of the rotor plate 15 is satisfied. . Then, if it is determined that all the tolerance learning conditions described above are satisfied, the tolerance learning is performed in step 122, and if not, the process skips to step 123.

Here, the procedure of the tolerance learning in step 122 will be described with reference to FIG. FIG. 5 is a time chart in the case where the current calculation time is the time when B of # 2 falls off. First, TDC-290 containing A
As the time between CAs, the latest value TSPARK2 [i] and the immediately preceding value TSPARK2 [i-2] are measured.
TSPAR as the time between TDC-290CA including
A value TSPARK2 [i-1] immediately before K2 [i] is measured. Each of the measured values TSPARK2 [i], TSPARK
Based on 2 [i-2] and TSPARK2 [i-1], an ignition cycle deviation (dltt) is calculated by the following equation (1). dltt = TSPARK2 [i] + TSPARK2 [i−2] −2 × TSPARK2 [i−1] (1) Then, the ignition cycle deviation (dl) calculated by the above equation (1)
tt) and the ignition cycle deviation angle (d
ltst). dltst = dltt × KDSOMG3 / (TSPARK3 [i] + TSPARK3 [i-1]) (2) In the above equation, KDSOMG3 is a constant, TSPARK3 [i] is the time between TDC-180CA this time, and TSPARK3.
[i-1] is the time between the previous TDC and 180CA.
The ignition cycle deviation angle (dlts) obtained by the above equation (2)
t) is subjected to a smoothing process for obtaining an average value of a predetermined number of times (for example, 30 times) for each rotation speed of the engine 11, the smoothed value is stored as a learning value, and the learning value in a rotation table is stored. Is subjected to linear interpolation processing to obtain a tolerance learning value (dlt
sth).

As described above, when the tolerance learning is performed in step 122, it is determined in step 123 whether the tolerance learning has been completed. When it is determined that the tolerance learning has been completed, in step 124, after the misfire detection described below is executed, step 1 is executed.
Returning to step 01, if it is determined that the tolerance learning has not been completed, step 124 is skipped and the process returns to step 101.

Here, referring again to FIG.
The procedure for detecting misfire at 24 will be described. As described above, FIG. 5 exemplifies the case where the current calculation time is the falling point of the signal # 2, so that the procedure for detecting the opposing misfires of # 2 and # 3 will be described below. . First, the latest TS between TDC-290CA
Calculate the time from PARK2 [i] to the time TSPARK2 [i-4] between the four previous TDC-290CA. Then, based on the calculated time, an angular velocity omgh [i-4] four times before the latest angular velocity omgh [i] corresponding to each is calculated by the following equation (3). Here, KDSMG2 is a constant. omgh = (KDSOMG2 + dltsth) / TSPARK2 (3) Next, an angular velocity deviation (domgh) is calculated by the following equation (4). domgh = ((omagh [i-4] -omagh [i-3] -omagh [i-3] + omgh [i-2]) + (omagh [i-2] -omagh [i-1] -omagh [ i-1] + omgh [i])) / 2 (4) In the above equation (4), the left term on the right side (omgh [i-4]-
omgh [i-3] -omgh [i-3] + omgh [i-
2]), the misfire of # 2 is detected, and the right term (omg [i
-2] -omagh [i-1] -omagh [i-2] + omg
h [i]), the misfire of # 3 is detected. That is, when the misfire of # 2 occurs, the angular velocity (omgh [i-3]) corresponding to the # 2 cylinder decreases, and the angular velocities before and after it (omagh [i-4], omagh [i-2]) increase. , The value of the left term on the right side increases. When the misfire of # 3 occurs, the angular velocity (omgh [i−
1]) becomes smaller, and the angular velocities before and after (omgh [i−
2] and omgh [i]) are large, so the value of the right term on the right side is large. Therefore, when the cylinders # 2 and # 3 misfire, the angular velocity deviation (domgh) becomes large.

Then, the angular velocity deviation (domgh) obtained by the above equation (4) is smoothed by the following equation (5): domgnh = TKDOMMGNH × domgnh [i-2] + (1-TKDOMGNH) × domgh ... (5) (TKDOMMGNH is an annealing coefficient) The value (domn) after the annealing process obtained by the above equation (5)
If h) is greater than or equal to the reference (dltref), the counter misfire is detected when the counter is counted a predetermined number of times.

[0027]

As described above, according to the present invention, the tolerance learning is prohibited for a predetermined time after the feedback correction value is reset. Accuracy can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an engine including an engine misfire detection device according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the embodiment of the present invention.

FIG. 4 is a time chart showing the operation of the embodiment of the present invention.

FIG. 5 is a time chart showing the operation of the embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing a rotation angle detection device.

FIG. 7 is a time chart showing the operation of the conventional example.

[Explanation of symbols]

 11 engine 17 rotation angle sensor 37 electronic control unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tamotsu Kamakura 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda F-term (reference) 3G019 AB02 AC01 AC02 AC04 AC05 CD01 DB02 DB14 DC01 GA01 GA02 GA05 GA10 GA11 GA16 GA19 GA20 3G084 BA06 BA09 BA13 BA27 CA01 CA02 CA04 CA06 DA27 EA04 EA07 EA08 EA11 EB11 EB19 EB24 EB25 FA02 FA06 FA07 FA18 FA20 FA24 FA29 FA33 FA36 FA38 FA39 3G301 HA14 JA23 JB09 KA01 KA05 KA12 NA01 KA04 KA04 ND24 ND30 NE17 NE19 NE23 PA01Z PA10Z PA18Z PA19Z PB03Z PC09Z PD03A PD03Z PD15Z PE01Z PE03Z PE05Z PE08Z PF05Z PF16Z

Claims (3)

[Claims] 1. A rotation angle detecting means for detecting a rotation angle of an output shaft of an engine, a learning means for obtaining a tolerance of the rotational angular velocity, and learning the tolerance, a learning means for learning the tolerance, Rotation angle correction means for correcting the rotation angle detected by the rotation angle detection means, feedback control means for detecting the air-fuel ratio of the combustion gas of the engine, and performing feedback control based on a feedback correction value obtained from the air-fuel ratio; During the control by the feedback control means, the learning of the tolerance is performed while the feedback correction value is sticking to the predetermined upper limit value or the lower limit value and until a predetermined time has elapsed after the feedback correction value is reset. An engine misfire detection device, comprising: a learning prohibition unit that prohibits learning. 2. The engine misfire according to claim 1, wherein the predetermined time during which the tolerance learning is prohibited is determined based on a time required for the correction value to substantially converge after the feedback correction value is reset. Detection device. 3. The engine misfire detection device according to claim 1, wherein the predetermined time during which the tolerance learning is prohibited can be changed in accordance with the engine speed.