JPH04362255A - Failure diagnosis device of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable speedy diagnosis of failure in an internal combustion engine with accuracy by taking notice of 'negative' which appears to 'positive' in the direction of change based on the direction of change of angular spped in the predetermined angle section which is obtained per the predetermined rotation angle in the predetermined acceleration condition of internal combustion engine. CONSTITUTION:In an engine 1 of, for example, a four cylinder ignition type which is mounted in a vehicle, a crank angle sensor 18 outputs a crank angle signal per a predetermined rotation angle. Also, a cylinder identification sensor 19 outputs a cylinder identification signal per suction top dead center of a predetermined cylinder. Further, a controller 17 identifies whether there is abnormality (for example, misfire) in the engine 1 or not per cylinder. At this time, the controller 17 judges failure of the engine 1 based on the direction of change of angular speed in the predetermined angle section which is obtained per the predetermined rotation angle. That is, the failure diagnosis device judges failure by taking notice of whether angular acceleration is below 0 or not and whether the direction of change of angular speed in the angle section where crank angle in the range from 0 deg. to 180$0 is 'negative' or not.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a failure diagnosis device for an internal combustion engine that can quickly and accurately determine a failure (for example, a misfire) in the internal combustion engine.

0002

[Prior Art] Conventionally, in this type of failure diagnosis device, a temperature sensor is provided in the exhaust pipe of an internal combustion engine (hereinafter simply referred to as the engine) or in a catalyst that purifies exhaust gas, and the temperature detected by the temperature sensor is set at a predetermined level. When this value was exceeded, this was determined to be a misfire resulting in the combustion of unburned gas in the exhaust pipe, and a failure indicator lamp was lit.

0003

[Problems to be Solved by the Invention] However, in the conventional failure diagnosis device described above, there is a time delay from when a misfire occurs until the temperature detected by the temperature sensor exceeds a predetermined value, that is, it takes time to determine a misfire. During this time, the engine, exhaust purification system, etc. may suffer burnout. Additionally, during this period, the engine continues to operate while emitting harmful exhaust gas, which has a negative impact on the environment.

0004

[Means for Solving the Problems] The present invention has been proposed to solve such problems, and the first invention (invention according to claim 1) is to Based on the direction of change in angular velocity in a predetermined angular interval determined for each rotation angle, engine failure is determined by focusing on the "negative" change direction that appears in contrast to the "positive" change direction. . In addition, the second invention (invention according to claim 2) is based on the change direction of the angular velocity in a predetermined angular interval obtained for each predetermined rotation angle in a predetermined deceleration state of the engine, This system is designed to determine engine failure by focusing on the "positive" direction of change that appears. Further, the third invention (invention according to claim 3) provides that, in a predetermined acceleration state of the engine, based on the amount of change in angular velocity in a predetermined angular section obtained for each predetermined rotation angle, the change in angular velocity in another predetermined angular section is Establish a comparison standard value using the amount of change in angular velocity as a reference,
If the amount of change in angular velocity in the predetermined angle section differs from this comparison reference value by more than a predetermined value, this is determined to be an abnormal combustion state in the predetermined angle section. Further, the fourth invention (the invention according to claim 4) provides that, in a predetermined deceleration state of the engine, based on the amount of change in angular velocity in a predetermined angle section obtained for each predetermined rotation angle, the change in angular velocity in another predetermined angle section is Establish a comparison standard value using the amount of change in angular velocity as a reference,
If the amount of change in angular velocity in the predetermined angle section differs from this comparison reference value by more than a predetermined value, this is determined to be an abnormal combustion state in the predetermined angle section. Further, the fifth invention (the invention according to claim 5) provides a first predetermined rotation angle obtained for each first predetermined rotation angle in a predetermined operating state of the engine (for example, an acceleration state, a deceleration state, a steady operating state). Changes in angular velocity in other cylinders based on the amount of change for each cylinder between the first angular velocity in the angular interval and the second angular velocity in the second predetermined angle interval determined for each second predetermined rotation angle. A comparison standard value is determined using the amount as a reference, and if the amount of change in angular velocity in the cylinder concerned differs from this comparison standard value by more than a predetermined value,
This is determined to be an abnormal combustion state in the relevant cylinder.

[0005]

[Operation] Therefore, in the first invention, based on the change direction "negative" that appears with respect to the change direction "positive" that continues uniformly, for example, the change direction "negative" at the same rotation angle is Based on the number of occurrences of cancellation with "correct", if the number of occurrences of cancellation exceeds a predetermined value, it can be determined that the engine has failed. In addition, in the second invention, based on the change direction "positive" that appears with respect to the change direction "negative" that continues uniformly, for example, the change direction "positive" at the same rotation angle is
Based on the number of occurrences of cancellation with "negative", if the number of occurrences of cancellation exceeds a predetermined value, it can be determined that the engine has failed. Further, in the third and fourth inventions, the average or weighted average of the amount of change in angular velocity in a predetermined angular interval for each predetermined rotation angle is determined as a comparison reference value, and the change in the angular velocity with respect to this comparison reference value. If the amounts differ by more than a predetermined value, this can be determined to be an abnormal combustion state in that angle section. Further, in the fifth invention, a comparison reference value is determined as an average or a weighted average of the amount of change between the first angular velocity and the second angular velocity for each cylinder, and the amount of change in the angular velocity is determined with respect to this comparison reference value. If they differ by a predetermined value or more, this can be determined to be an abnormal combustion state in that cylinder.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a failure diagnosis apparatus for an internal combustion engine according to the present invention will be explained in detail.

FIG. 1 is a diagram showing the configuration of an engine section to which an embodiment of this failure diagnosis device is applied. In the figure, for example, a four-cylinder spark ignition engine 1 mounted on a vehicle is connected from an air cleaner 3 to an intake manifold.
An amount of air corresponding to the opening degree of a throttle valve 5, which opens and closes in conjunction with the accelerator pedal, is sucked through the throttle valve 2. Intake manifold pressure (hereinafter referred to as intake manifold pressure) P in the intake manifold 2 downstream of the throttle valve 5 is detected as an absolute pressure by a pressure sensor 6. The temperature of the intake air is detected by an intake temperature sensor 10. Further, the coolant temperature of the engine 1 is detected by a coolant temperature sensor 11 .

Fuel is supplied to the first cylinder (#1) to the fourth cylinder (#4) injectors 4 provided for each cylinder of the engine 1.
The mixture is injected and supplied from the selected injectors 1 to 44 under the control of a control device 17, which will be described later, and is inhaled into the engine 1 as an air-fuel mixture. Hereinafter, the G-th cylinder (G is 1, for example)
~4 integer) is expressed as #G.

On the other hand, the igniter 12 which receives the ignition signal from the signal generator unit cuts off the current in the primary side coil of the ignition coil 13 and generates high voltage on the secondary side of the ignition coil 13. This high pressure is supplied via the distributor to a spark plug (not shown) provided in the relevant cylinder of the engine 1 that requires ignition, ignites it, and causes the cylinder to perform an explosion process.

Exhaust gas from the engine 1 passes through a three-way catalyst 8 provided in a common exhaust passage of an exhaust manifold 7, is purified, is guided to the exhaust manifold 7, and is discharged to the outside.

As the crankshaft (not shown) of the engine 1 rotates, the crank angle sensor 18 outputs a crank angle signal at every predetermined rotation angle, for example, 1 degree (see FIG. 10(b)).
In addition, the cylinder identification sensor 19 outputs a cylinder identification signal for each intake top dead center of the #1 cylinder (see FIG. 5(a)), and the crank angle signal is output depending on the crank angle (see FIG. 10(g)). Determine whether the angle is indicated.

14 is a cranking switch, 15 is a battery, 16 is a key switch, 17 is a control device, 20 is a throttle opening sensor, and 501 to 504 are #1 to #4 indicator lamps.

FIG. 2 is a block diagram showing the detailed internal configuration of the control device 17 etc. shown in FIG. 1. key switch 1
6 turns on, the control device 17 receives constant voltage from the battery 15 via the first power supply circuit 105 and starts operating. At this start of operation, the engine 1 temporarily receives driving force from a starter (not shown), receives fuel, and starts. The cranking switch 14 is turned on as the starter starts operating. This on signal is input via the third input interface circuit 103 and input port 204. Further, the RAM 205 receives power from the battery 15 via the second power supply circuit 106 regardless of whether the key switch 16 is on or off and is nonvolatile.

The CPU 200 operates according to the control programs shown in the flowcharts shown in FIGS. 3 to 8, which are stored in the ROM 206. A microcomputer 100 in the control device 17 controls the crank angle sensor 18 to the first
A signal change in the crank angle sensor signal is input as an interrupt input signal via the input interface circuit 101. The generation cycle of this interrupt input signal is measured by the counter 201, and the engine rotation speed N is determined by the CPU 200.
The average rotational speed data for two engine revolutions representing E is converted into a NED bar.

The control device 17 also converts analog detection signals from the pressure sensor 6, intake temperature sensor 10, and cooling water temperature sensor 11 into analog-to-digital signals via a second input interface circuit 102 and an A/D converter 203. A/D) conversion to obtain digital signals of intake manifold pressure value PD and intake air temperature value TA.
, the cooling water temperature value TW, and sequentially read the cooling water temperature value TW. These values P
D, TA, and TW increase, for example, in proportion to increases in detected pressure and detected temperature.

The control device 17 calculates the basic fuel using a well-known method based on the rotation speed data NED bar and the intake manifold pressure value PD, corrects it based on the intake air temperature value TA and the cooling water temperature value TW, and calculates the basic fuel value from #1 to ##. The drive time of the four injectors 41 to 44 is determined, and the drive time of the #1 to #4 injectors 41 to 44 is controlled using the timer 202 from the output port 207 via the output interface circuit 104.

Further, the control device 17 executes the control programs shown in FIGS. 3 to 8 to identify whether or not there is an abnormality in the engine 1 for each cylinder. If there is an abnormality, the control device 17 executes the control programs shown in FIGS. The display lamps #1 to #4 indicating lamps 501 to 504 corresponding to the cylinder with the abnormality are turned on.

Note that the control device 17 is designated by reference numerals 101 to 10.
6 elements, elements 200 to 207, and a bus 208 connecting them.
Consists of 0.

As described above, the control device 17 executes the flowchart of the main routine (not shown) upon the start of operation and calculates the fuel injection amount. The execution of the flow of the main routine is interrupted, and the control programs (interrupt processing routine) shown in FIGS. 3 to 8 are executed. This control program includes techniques corresponding to the first and second inventions of the present application.

The operation contents of this control program will be explained below. First, in step 301, the number NO of crank angle signals (1 degree angle signal) generated is counted. Now, suppose that a cylinder identification signal is generated (Fig. 10(a)
t1 point shown in ), and in response to "Y" in step 302, the counted number of occurrences NO is set to zero (step 306
), stores the current time in register T0 (step 30
7). Then, the process proceeds to step 308, where 180°/(T
0-T540), the angular velocity V540 in the angular interval from crank angle 540° to 0° is determined. Also, V540
-V360, determine the angular acceleration A540 in the angular interval from crank angle 540° to 0°.

If the cylinder identification signal is not generated, the process proceeds to step 303 in response to "N" in step 302. If the number of occurrences NO is 180 in step 303 (
t2 point shown in FIG. 5(a)), the current time is stored in the register T180 (step 311), and the process proceeds to step 312. In step 312, the angular velocity V0 in the angular range from 0° to 180° is determined by 180°/(T180-T0). Further, the angular acceleration A0 in the angular range from 0° to 180° is determined from V0-V540.

[0022] In step 304, the number of occurrences NO is 360.
If so (point t3 shown in FIG. 10(a)), register T3
The current time is stored in 60 (step 313), and the process advances to step 314. In step 314, 180°/(T3
60-T180), crank angle from 180° to 36
Find the angular velocity V180 in the 0° angle section. Also, V
The angular acceleration A180 in the angular range from 180° to 360° of crank angle is determined from 180-V0.

[0023] In step 305, the number of occurrences NO is 540.
If so (point t4 shown in FIG. 10(a)), register T5
The current time is stored in 40 (step 315), and the process advances to step 316. In step 316, 180°/(T5
40-T360), crank angle from 360° to 54
Find the angular velocity V360 in the 0° angle section. Also, V
360-V180 allows crank angle from 360° to 54
Find the angular acceleration A360 in the 0° angle section.

After determining the angular velocity V540 and the angular acceleration A540 in step 308, the process proceeds to step 309, and based on the rotational speed data NED bar and the intake manifold pressure value PD, the engine operating state is determined to be abnormal as shown in the shaded area in FIG. It is determined whether or not it is within the determination zone Z. This engine abnormality determination zone Z is a predetermined operating region, and is stored in the ROM 206 in the form of a data table. Step 3 above
In step 09, it is determined whether or not the vehicle is within zone Z using this data table. If it is within the engine abnormality determination zone Z, the process immediately proceeds to step 320, and if it is outside the zone Z, the process proceeds to step 310, where the delay timer value TM is reset to zero. The timer of this timer value TM is, for example, a soft timer, and is counted up every predetermined time or every predetermined number of steps by an interrupt processing routine or a main routine.

Note that in the engine abnormality determination zone Z shown in FIG. 9, instead of the intake manifold pressure P, the intake air amount,
It may be defined by the filling efficiency obtained by dividing the intake air amount by the cylinder volume, the Karman air flow sensor output frequency, the throttle valve opening degree, etc. In addition, conditions may be added as the engine abnormality determination zone Z, such as when the cooling water temperature is above a predetermined value, after a predetermined time after starting the engine, when fuel cut is not performed, and when idle stabilization control is not performed.

At step 320, the throttle opening data previously stored in the register TPS is stored in the register TPSO as the previous throttle opening data. Further, following this, the current throttle opening data is stored in the register TPS, and throttle opening change amount data dTPS is obtained by TPS-TPSO. Then, the process advances to step 321 and (A540+A0+A180+A3
60)/4, calculate the average crank angular acceleration value A bar during the four strokes.

Crank angular acceleration average value A bar is a predetermined value A
If it is 1 or more (A bar≧A1), it is determined in step 322 that the vehicle is accelerating, and the process proceeds to step 323. Crank angular acceleration average value A bar is less than predetermined value A2 (A bar ≦
If A2), it is determined in step 327 that the vehicle is decelerating, and the process proceeds to step 328. In addition, A1 and A2
has the relationship A1>0>A2.

If it is determined in step 322 that the vehicle is being accelerated and the process proceeds to step 323, it is checked in step 323 whether "FLAGA" is set to 1 or not. If "FLAGA" is not set to 1,
The process proceeds to step 324 as the first acceleration determination, and the “FLAGA
" is 1, "FLAGD" and delay timer value T
Set M to zero and proceed to step 325. "FLAGA"
If it is set to 1, the process immediately proceeds to step 325. In step 325, it is confirmed that the throttle opening change amount data dTPS at this time is 0 or more (dTPS≧0), and the process immediately proceeds to step 340. If dTPS is 0 or less, it is assumed that the throttle has been decelerated and step 3
The process proceeds to step 26, where "FLAGA" is set to zero, the delay timer value TM is set to zero, and the process proceeds to step 340.

In step 340, the delay timer value T
M and the predetermined delay time TM0 until the start of failure determination
Compare with and confirm that TM−TM0≧0,
The process moves to abnormality determination processing (failure determination processing) in a predetermined acceleration state from step 341 onwards. FIG. 11 shows an example of a failure determination area during acceleration. In this case, the abnormality determination process is started after TM0 time has elapsed from the time t1 when it was determined that the A bar is equal to or greater than A1.

In step 341, it is determined whether the angular acceleration A0 is less than 0 (A0<0), that is, the direction of change in the angular velocity in the angular range from 0° to 180° is negative.
If it is negative, count value CA4 of #4 counter (not shown) is counted up (step 342). The direction of change of the above angular velocity is "positive"
If so, the count value CA4 is counted down (step 343). Then, it is checked whether the count value CA4 is equal to or greater than a predetermined number of failure determinations CF (CA4≧CF) (step 344), and if CA4 is equal to or greater than CF, the #4 indicator lamp 504 is turned on (step 344). 345). If CA4 is below CF, #4 indicator lamp 5
04 is turned off (step 346). In other words, the direction of change in the angular velocity that appears at a crank angle of 180° is
If the number of offset occurrences of “negative” and “positive” exceeds CF, #4
It is determined that a misfire has occurred in the cylinder, and the #4 indicator lamp 50
Turn on 4.

[0031] Thereafter, in the same manner, steps 347 and 36 are performed.
Angular acceleration A180, A360, A540 at 1,367
Check whether or not is less than 0, and if it is less than 0, #2,
Count value CA2 at #1 and #3 counters (shown)
, CA1, and CA3 (step 348).
, 362, 368), if it is 0 or more, the count value CA2
, CA1, and CA3 (step 349).
, 363, 369), count values CA2, CA1, CA
3 is equal to or greater than a predetermined number of failure judgments CF (steps 350, 364, 370), and CA2
, if CA1 and CA3 are greater than or equal to CF, #2, #1, #3
The indicator lamps 502, 501, 503 are turned on (steps 351, 365, 371), and when CA2, CA1, and CA3 are below CF, the #2, #1, and #3 indicator lamps 502,
Turn off lights 501 and 503 (steps 352, 366,
372).

On the other hand, if it is determined in step 327 that the vehicle is decelerating and the process proceeds to step 328, it is checked in step 328 whether "FLAGD" is set to 1 or not. If "FLAGD" is not set to 1, the process proceeds to step 329 as the first deceleration determination, and "FLAG
D" is set to 1, "FLAGA" and the delay timer value TM are set to zero, and the process proceeds to step 330. “F.L.A.G.D.
” is set to 1, the process immediately proceeds to step 330. In step 330, it is confirmed that the throttle opening change amount data dTPS at this time is less than or equal to 0 (dTPS≦0), and the process immediately proceeds to step 380. dTPS
If 0 or more, it is assumed that the throttle has been accelerated and the process proceeds to step 331, where "FLAGD" is set to zero, the delay timer value TM is set to zero, and the process proceeds to step 380.

In step 380, the delay timer value T
M and the predetermined delay time TM0 until the start of failure determination
Compare with and confirm that TM−TM0≧0,
The process moves to abnormality determination processing (failure determination processing) in a predetermined deceleration state from step 381 onwards.

In step 381, it is determined whether the angular acceleration A0 is 0 or more (A0>0), that is, the direction of change of the angular velocity in the angular range from 0° to 180° of the crank angle is “positive”.
If it is "correct", count value CD4 of #4 counter (not shown) is counted up (step 382). The direction of change of the above angular velocity is "negative"
If so, the count value CD4 is counted down (step 383).

[0035] Similarly, steps 384 and 38
Angular acceleration A180, A360, A540 at 7,390
Check whether or not is greater than or equal to 0, and if it is greater than or equal to 0, #2,
Count values CD2, CD1, C at #1 and #3 counters
Count up D3 (steps 385, 388, 3
91), if it is less than 0, the count value CD2, CD1, C
Count down D3 (steps 386, 389,
392).

[0036] Then, the count values CD1, CD2, CD
3. Compare the maximum value in CD4 with the failure judgment count CF (step 393), and if the maximum value is greater than or equal to CF, simultaneously light the #1 to #4 indicator lamps 501 to 504 (step 394), and If the maximum value is less than CF
, #1 to #4 display lamps 501 to 504 are simultaneously turned off (step 395).

FIG. 12 is a diagram showing a situation where the #1 cylinder misfires in a predetermined acceleration state. Since a misfire has occurred in the #1 cylinder at the point "x" shown in (e) of the same figure, the angular acceleration A360 becomes "negative",
When the number of occurrences of "negative" offset becomes equal to or greater than CF, the #1 indicator lamp 501 lights up, indicating a misfire in the #1 cylinder.

[0038]Additionally, in the above embodiment,
When there is a misfiring cylinder in a predetermined deceleration state, abnormality detection due to misfire is carried out by utilizing the fact that the crank angular acceleration of the engine fluctuates greatly due to torque fluctuation, but at this time, it is difficult to identify the misfiring cylinder. 1 to #4 indicator lamps 501 to 504 are turned on and off at the same time to indicate that there is a failure in any of the cylinders.

The flowcharts shown in FIGS. 13 to 16 show modifications of the above-mentioned control program, in which the abnormality determination in a predetermined deceleration state is canceled in contrast to the above-described embodiment. In other words, the processes after step 327 shown in FIG. 4 are omitted (see FIG. 14).
reference). In addition, when determining an abnormality in a predetermined acceleration state, the #1
~#4 The display lamps 501 to 504 are turned on and off at the same time (see FIGS. 15 and 16).

[0040] In the above-mentioned embodiment, 180
The angular velocity for each angular velocity section was determined, and the direction of change in the angular velocity, that is, the sign of the angular acceleration, was determined and compared.
For example, the angular velocity in angular sections of 180°, 90°, 1°, etc.) may be determined, and the direction of change in the angular velocity may be determined and compared. For example, from 45 degrees after top dead center of each cylinder,
The angular velocity may be determined for each angular interval of 35 degrees, and the difference from the previous angular velocity, that is, the angular acceleration, may be determined and compared.

Further, in the above-described embodiment, when a cylinder with an abnormality can be identified, the #1 to #4 indicator lamps 501 to 504 corresponding to the identified cylinder are lit; It is also possible to stop the fuel supply to the cylinder that has been stopped.

The flowcharts shown in FIGS. 17 to 22 are control programs including techniques corresponding to the third and fourth inventions of the present application. In this control program, in a predetermined acceleration state (deceleration state), the 18
The angular acceleration in the 0° section is compared with the average value of the angular accelerations in all 180° sections, and the angular acceleration in the 180° section is determined by a predetermined value AF (DF) with respect to the average value of the angular accelerations.
) or more, this is determined to be a combustion abnormality in the relevant section. For example, regarding the angular acceleration A0, in a predetermined acceleration state, it is checked whether A0 < A bar - AF (step 841), and if A0 is less than A bar - AF, the count value CA4 is incremented. (step 342), and if it is above, the count value CA4
is counted down (step 343). Also, in a predetermined deceleration state, it is checked whether A0<A bar - DF (step 881), and if A0 is less than A bar - DF, the count value CD4 is incremented (step 382); If so, the count value CD4 is counted down (step 383).

The flowcharts shown in FIGS. 23 to 26 show modifications of the above-described control program (FIGS. 17 to 22). I take it as a thing. That is,
The processing after step 327 shown in FIG. 18 is omitted (see FIG. 24).

The flowcharts shown in FIGS. 27 to 33 also show modifications of the above-mentioned control program (FIGS. 17 to 22). In this example, in a predetermined acceleration state (deceleration state), the 180° The angular acceleration of the section and all 18
The weighted average obtained by weighting the angular acceleration in the 0° interval is compared, and if the angular acceleration in the 180° interval differs by more than a predetermined value AF (DF) from the weighted average, this is It is determined that there is a combustion abnormality in the section. For example, regarding the angular acceleration A0, in a predetermined acceleration state, it is checked whether A0 < A0 bar - AF (step 841), and if A0 is less than A0 bar - AF, the count value CA4 is incremented. (Step 342), and if the count value CA4 is greater than that, the count value CA4 is counted down (Step 343). Also, in a predetermined deceleration state, check whether A0 < A0 bar - DF (
Step 881), if A0 is less than or equal to A0 bar - DF, count up the count value CD4 (step 382).
), the count value CD4 is counted down (step 383). Weighted average A0 bar is step 3
26-1 (see FIG. 29). That is, k1, k2
, k3, k4 are determined in advance as predetermined non-negative values (k1
, k2, k3, k4≧0), this coefficient k1, k2, k3
, k4 to weight A0, A180, A360, and A540 to obtain a weighted average A0 bar. Now, k1=
If k2=k3=k4, it becomes equivalent to the control programs shown in FIGS. 17 to 22. As a result, Figures 17 to 2
It can be seen that the control program shown in FIG. 2 is a special case of the control programs shown in FIGS. 27-33.

In the above, AF and DF were determined as fixed values, but depending on the engine speed Ne and intake manifold pressure P, AF=fA (Ne, P), DF=fD
It may also be a function that becomes (Ne, P). Further, instead of the intake manifold pressure P, the intake air amount, the filling efficiency obtained by dividing the intake air amount by the cylinder volume, the Karman air flow sensor output frequency, the throttle valve opening degree, etc. may be used. Alternatively, the function may be defined by only one of the amount of change and the engine speed. In addition, in the above embodiment, the simple average value of all 180° sections was changed to a weighted average and compared with the angular acceleration of the 180° section, but when compared with one of the other 180° sections, It is also possible to determine an abnormality.

The flowcharts shown in FIGS. 34 to 42 are control programs including techniques corresponding to the fifth invention of the present application. In this control program, in a predetermined acceleration state (deceleration state, steady operation state), the angular velocity around the top dead center (first predetermined rotation angle) (first predetermined angle section) at the start of the expansion stroke and the expansion stroke 90° after top dead center (
Weighting is applied to the angular acceleration in that cylinder and the angular acceleration in all cylinders based on the amount of change for each cylinder, that is, the angular acceleration, between the angular velocity before and after (the second predetermined rotation angle) (the second predetermined angle section). The angular acceleration in the cylinder is determined by a predetermined value AF (DF
, SF), this is determined to be a combustion abnormality in the relevant cylinder.

The flowcharts shown in FIGS. 43 to 48 show modifications of the above-mentioned control program (FIGS. 34 to 42). It is assumed that When abnormal combustion is determined in a predetermined acceleration state and deceleration state, #1 to #4 indicator lamps 501 to 504 are simultaneously turned on.

[0048]

As is clear from the above explanation, according to the present invention, engine failure, such as a misfire, can be quickly and accurately determined, and the detection results can be displayed and the misfired cylinder can be detected. By stopping the fuel supply, it is possible to prevent damage to the engine, exhaust purification device, etc., and to prevent continued operation while emitting harmful exhaust gas.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an engine section to which an embodiment of a failure diagnosis device according to the present invention is applied.

FIG. 2 is a diagram showing a detailed internal configuration of the control device etc. shown in FIG. 2;

FIG. 3 is a diagram showing a divided control program including techniques corresponding to the first invention and the second invention of the present application.

FIG. 4 is a diagram showing this control program divided.

FIG. 5 is a diagram showing this control program divided.

FIG. 6 is a diagram showing this control program divided.

FIG. 7 is a diagram showing this control program divided.

FIG. 8 is a diagram showing this control program divided.

FIG. 9 is a diagram showing an engine abnormality determination zone Z.

FIG. 10 is a time chart for explaining the operation of the control program divided and shown in FIGS. 3 to 8;

FIG. 11 is a diagram showing an example of a failure determination area during acceleration.

FIG. 12 is a diagram showing a situation where #1 cylinder misfires in a predetermined acceleration state.

FIG. 13 is a diagram showing a modified example of the control program divided into parts.

FIG. 14 is a diagram showing this control program divided.

FIG. 15 is a diagram showing this control program divided.

FIG. 16 is a diagram showing this control program divided.

FIG. 17 is a diagram showing a divided control program including a technique corresponding to the third invention and the fourth invention of the present application.

FIG. 18 is a diagram showing this control program divided.

FIG. 19 is a diagram showing this control program divided.

FIG. 20 is a diagram showing this control program divided.

FIG. 21 is a diagram showing this control program divided.

FIG. 22 is a diagram showing this control program divided.

FIG. 23 is a diagram showing a modified example of the control program divided into parts.

FIG. 24 is a diagram showing this control program divided.

FIG. 25 is a diagram showing this control program divided.

FIG. 26 is a diagram showing this control program divided.

FIG. 27 is a diagram showing a further modified example of the control program divided into sections.

FIG. 28 is a diagram showing this control program divided.

FIG. 29 is a diagram showing this control program divided.

FIG. 30 is a diagram showing this control program divided.

FIG. 31 is a diagram showing this control program divided.

FIG. 32 is a diagram showing this control program divided.

FIG. 33 is a diagram showing this control program divided.

FIG. 34 is a diagram showing a divided control program including a technique corresponding to the fifth invention of the present application.

FIG. 35 is a diagram showing this control program divided.

FIG. 36 is a diagram showing this control program divided.

FIG. 37 is a diagram showing this control program divided.

FIG. 38 is a diagram showing this control program divided.

FIG. 39 is a diagram showing this control program divided.

FIG. 40 is a diagram showing this control program divided.

FIG. 41 is a diagram showing this control program divided.

FIG. 42 is a diagram showing this control program divided.

FIG. 43 is a diagram showing a modified example of the control program divided into parts.

FIG. 44 is a diagram showing this control program divided.

FIG. 45 is a diagram showing this control program divided.

FIG. 46 is a diagram showing this control program divided.

FIG. 47 is a diagram showing this control program divided.

FIG. 48 is a diagram showing this control program divided.

[Explanation of symbols]

1 Engine 17 Control device 18 Crank angle sensor 19 Cylinder identification sensor 20 Throttle opening sensor 100 Microcomputer 501 #1 indicator lamp 502 #2 indicator lamp 503 #3 indicator lamp 504 #4 indicator lamp

Claims (5)

[Claims] Claim 1: In a predetermined acceleration state of an internal combustion engine,
A failure determination means for determining a failure of the engine based on the direction of change in angular velocity in a predetermined angular interval determined for each predetermined rotation angle, focusing on a "negative" change direction that appears with respect to a "positive" change direction. A failure diagnosis device for internal combustion engines. [Claim 2] In a predetermined deceleration state of the internal combustion engine,
A failure determination means is provided for determining a failure of the engine based on the direction of change in angular velocity in a predetermined angular interval determined for each predetermined rotation angle, focusing on a "positive" change direction that appears in response to a "negative" change direction. A fault diagnosis device for internal combustion engines. [Claim 3] In a predetermined acceleration state of the internal combustion engine,
Based on the amount of change in angular velocity in a predetermined angular section calculated for each predetermined rotation angle, a comparison reference value is determined with reference to the amount of change in angular velocity in other predetermined angular sections, and the comparison standard value is determined based on the amount of change in angular velocity in a predetermined angular section calculated for each predetermined rotation angle. A failure diagnosis device for an internal combustion engine, comprising a failure determination means for determining an abnormal combustion state in the predetermined angle section when the amount of change in angular velocity differs by a predetermined value or more. Claim 4: In a predetermined deceleration state of the internal combustion engine,
Based on the amount of change in angular velocity in a predetermined angular section calculated for each predetermined rotation angle, a comparison reference value is determined with reference to the amount of change in angular velocity in other predetermined angular sections, and the comparison standard value is determined based on the amount of change in angular velocity in a predetermined angular section calculated for each predetermined rotation angle. A failure diagnosis device for an internal combustion engine, comprising a failure determination means for determining an abnormal combustion state in the predetermined angle section when the amount of change in angular velocity differs by a predetermined value or more. [Claim 5] In a predetermined operating state of the internal combustion engine,
The first angular velocity in the first predetermined angle section obtained for each first predetermined rotation angle and the second angular velocity in the second predetermined angle section obtained for each second predetermined rotation angle for each cylinder. Based on the amount of change in the angular velocity in the other cylinders, a comparison reference value is determined with reference to the amount of change in the angular velocity in other cylinders. A failure diagnosis device for an internal combustion engine, comprising a failure determination means that determines that the combustion state in the cylinder is abnormal.