JP2004293350A - Device for detecting combustion state of internal combustion engine - Google Patents

Abstract

[PROBLEMS] To accurately detect a misfire over the entire rotation range even in a situation where the position of a misfire detection plate is easily affected by shaft vibration (torsion, eccentricity, etc.) of a crankshaft, combustion fluctuation, and plate manufacturing error. .
A time signal measuring unit measures a required time from a first crank angle to a second crank angle. Next, the actual combustion state parameter and the remaining combustion state parameter are calculated from the required time by the actual combustion state parameter calculation means. A combustion state parameter is calculated from the actual combustion state parameter and the remaining combustion state parameter, and the combustion state is determined by combustion state determination means.
In the abnormal combustion cylinder determination, the abnormal combustion cylinder is determined from the combustion state determination result, the actual combustion state parameter, the remaining combustion state parameter, and the ignition cylinder signal.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a combustion state detection device for an internal combustion engine, and more particularly to a combustion state detection device for an internal combustion engine that can perform a full range misfire diagnosis without impairing a detection rate in a high rotation region.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is known a technique for detecting an operating state by measuring a rotation speed by using a relationship between a torque generated by combustion of an engine and a rotation speed, and indirectly detecting a misfire. This technology detects the rotation speed of the internal combustion engine at least at least two ignitions in one ignition cycle from the previous ignition to the current ignition, and determines the rotation speed of the internal combustion engine in the one ignition cycle based on a difference between the rotation speeds. A variation value is obtained, the rotational speed variation value obtained sequentially is statistically calculated, and the combustion state of the internal combustion engine is determined using the result of the calculation process (for example, see Patent Document 1). .
[0003]
[Patent Document 1]
JP-A-58-51243
[Problems to be solved by the invention]
The diagnostic method described above can detect a torque fluctuation due to a misfire as a rotational speed fluctuation value in a relatively low rotational speed range, but it may be difficult to detect the torque fluctuation depending on the position of a misfire detection plate. For example, in the case of a six-cylinder engine, when the misfire detection plate is located on the front side of the engine, there is a disadvantage that it is easily affected by shaft vibration (torsion, eccentricity, etc.) of the crankshaft, combustion fluctuation, and plate manufacturing error. For this reason, in a high rotation region, a rotation speed fluctuation value due to misfire may be small, and a misfire signal is swallowed by these disturbances, making it difficult to detect misfire.
[0005]
Therefore, the present invention provides a method for controlling a misfire detection plate from a low rotation to a high rotation even if the position of the misfire detection plate is easily affected by shaft vibration (torsion, eccentricity, etc.) of the crankshaft, combustion fluctuation, and plate manufacturing error. An object of the present invention is to provide a combustion state detection device for an internal combustion engine that can accurately detect misfires over an entire region and an entire region.
[0006]
[Means for Solving the Problems]
A combustion state detection device for an internal combustion engine according to the present invention for solving the above problems is basically a detection device for detecting a combustion state of an internal combustion engine from a time signal obtained by measuring an elapsed time during which a crankshaft rotates a predetermined angle. Means for calculating an actual combustion state parameter; means for calculating a remaining combustion state parameter; combustion state parameter calculation means for calculating a combustion state parameter from the actual combustion state parameter and the remaining combustion state parameter; Means for calculating the combustion state from the calculation means, means for calculating the ignition cylinder signal, means for calculating the combustion state signal, means for calculating the actual combustion state parameter, means for calculating the remaining combustion state parameter, and means for calculating the ignition cylinder signal. Abnormal combustion cylinder determining means for determining an abnormal combustion cylinder.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example)
Hereinafter, a combustion state detection device and a detection method thereof according to the present invention will be described in detail based on embodiments. FIG. 1 shows a block diagram of the present invention. A time signal for a predetermined angle is detected by the time signal measuring means of the block 101, and an actual combustion state parameter is calculated by the actual combustion state parameter calculating means of the block. The remaining combustion state parameter is calculated by the remaining combustion state parameter calculation means in block 103, and the combustion state parameter is calculated by the combustion state parameter calculation means in block 104. The combustion state determination means in block 105 determines the combustion state from the combustion state parameter. On the other hand, the ignition cylinder signal is calculated by the ignition cylinder signal calculation means of block 107, and the ignition cylinder signal and the actual combustion state parameter, the remaining combustion state parameter, and the combustion state determination means are determined by the abnormal combustion cylinder determination means of block 106. The abnormal combustion cylinder is determined from the result of (1).
[0008]
The above is the outline of the present invention. Hereinafter, the internal combustion engine system to which the present invention is applied will be described.
[0009]
FIG. 2 shows an internal combustion engine system to which the present invention is applied. The engine comprises an internal combustion engine, an intake system, and an exhaust system. The internal combustion engine is provided with an ignition device 201, a fuel injection device 202, and a rotation speed detecting means 203. The flow rate of the air flowing from the air cleaner 200 is adjusted by a throttle valve 213, the flow rate is measured by a flow rate detecting means 204, and the air is mixed with fuel injected at a predetermined angle from the fuel injection device 202 to be mixed with each cylinder. 214. An air-fuel ratio sensor 205 and a three-way catalyst 206 are attached to the exhaust system, and exhaust gas is purified by the three-way catalyst 206 and then discharged to the atmosphere. The internal combustion engine control device 207 takes in the output signal Qa of the flow rate detection means 204 and the rotation speed Ne of the ring gear or the plate 208 by the rotation speed detection means 203, calculates the fuel injection amount Ti, and calculates the injection amount of the fuel injection device. Control. Further, the internal combustion engine control device 207 detects the air-fuel ratio in the internal combustion engine from the air-fuel ratio sensor 205 and corrects the fuel injection amount Ti so that the air-fuel ratio in the internal combustion engine becomes the stoichiometric air-fuel ratio. I do.
[0010]
On the other hand, the fuel in the fuel tank 209 is sucked and pressurized by the fuel pump 210, and then guided to the fuel inlet of the fuel injection device 202 through the fuel pipe 212 provided with the pressure regulator 211. Is returned to the fuel tank 209. In the present embodiment, a six-cylinder engine will be described as an example, but the present invention is not limited to this.
[0011]
FIG. 3 shows the rotation speed with respect to the crank angle of the engine. The solid line shows the waveform when the # 3 cylinder misfires, and the broken line shows the waveform when the combustion state is normal.
[0012]
In FIG. 3, a rotation speed measurement section (hereinafter, referred to as a window) for each cylinder will be described. The TDC (top dead center) of each cylinder is detected based on the reference signal REF. The first crank angle is obtained from the TDC using the angle signal POS and is set as the window start point Ws. The second crank angle is obtained from the window start point Ws using the same angle signal POS, and the window width W from the first crank angle to the second crank angle is determined.
[0013]
Now, let the window passage time of the cylinder in the ignition cycle be Tw (i), and obtain the actual combustion state parameter D1A1 from equation (1).
[0014]
D1A1 = {Tw (i) −Tw (i−1)} / Tw ³ (i) × k (1)
However,
Tw (i): Window W passage time of the cylinder currently in the ignition cycle Tw (i-1): Window W passage time k of the cylinder in the previous ignition cycle: Operation coefficient D1A1: Actual combustion state parameter Equation (1) is the engine When the combustion state is normal, the combustion state parameter D1A1 indicates zero because the window passage times of the cylinders are equal. When the engine misfires, no torque is generated in the misfiring cylinder and the number of rotations decreases, so that the value of Tw increases as shown in FIG. At this time, the combustion state parameter D1A1 shows a certain positive value as shown in FIG. Therefore, the presence or absence of a misfiring cylinder can be detected by comparing the combustion state parameter D1A1 with a preset value.
[0015]
The above method is effective in a low-rotation region (4000 r / min or less) of an engine having a small number of cylinders (4 cylinders or less) or an engine of a large number of cylinders (6 cylinders or more). In the rotation region, when the misfire detection plate is located on the front side of the engine, there is a drawback that the crankshaft is easily affected by shaft vibration (torsion, eccentricity, etc.), combustion fluctuation, and plate manufacturing error. FIG. 5 shows the window passing time Tw at 6000 r / min. In order to determine the presence or absence of a misfire by equation (1), a rotation fluctuation difference must occur between Tw of the misfire cylinder and Tw of the immediately preceding cylinder as shown in FIG. . However, in FIG. 5, misfires satisfying the condition are only the # 3 and # 5 cylinders, and other misfires cannot be detected by the equation (1). The present invention describes means for solving this problem.
[0016]
In order to solve the above problem, first, attention is paid to the window passing time Tw. The window passing time Tw in FIG. 4A is for a window width W = 90 °, and when the rotation speed is increased to 6000 r / min, the shaft vibration (torsion, eccentricity, etc.) of the crankshaft and the combustion fluctuation cause a misfire signal. And misfires cannot be determined, or misfire cylinders are erroneously determined even if misfires can be determined.
[0017]
Therefore, the window width W of the window passage time Tw is made as large as possible in order to smooth the influence of the shaft vibration of the crankshaft and the combustion fluctuation. In the present embodiment, since a six-cylinder engine is targeted, the window width W is limited to 120 °. FIG. 6 shows a window passing time Tw when the window width W at 4000 r / min is set to 120 °. As shown in the figure, while a rotational fluctuation difference due to misfire has occurred, a residual rotational fluctuation difference due to misfire has occurred thereafter. In this case, the misfire cannot be detected by the equation (1), but the presence or absence of the misfire can be determined by using the equation (2).
[0018]
D1A2 = {Tw (i) −Tw (i−2)} / Tw ³ (i) × k (2)
However,
Tw (i): Window W passage time of the cylinder in the current ignition cycle Tw (i-2): Window W passage time k of the cylinder in the second preceding ignition cycle k: Operation coefficient D1A2: Residual combustion state parameter Next, FIG. The window passing time Tw when the window width W at 6000 r / min is 120 ° is shown. From the figure, it can be seen that the residual fluctuation is dominant in the misfires of the # 1, # 3, # 4, and # 6 cylinders, but the actual fluctuation is dominant in the misfires of the # 2 and # 5 cylinders. That is, even if the window width W is changed to 120 °, it is not possible to detect from a low rotation to a high rotation region by one expression, but an expression having both characteristics of Expressions (1) and (2) is used. If it is, a misfire can be detected. When the window width W is set to 120 °, the remaining rotation fluctuation value due to the misfire becomes more dominant than the actual rotation fluctuation value due to the misfire, and furthermore, the operating range (engine speed, engine load) and the shaft vibration of the crankshaft ( (Torsion, eccentricity, etc.), and fluctuation of combustion. Although qualitative, the remaining rotation fluctuation value is a signal that is generated after the actual misfire occurs, and during this delay, the energy fluctuation due to the misfire is stored in the crankshaft, and as the rotation fluctuation at the next ignition timing It is considered to be detected. Here, it is assumed that the energy fluctuation stored in the crankshaft is much larger than the shaft vibration (torsion, eccentricity, etc.), combustion fluctuation, etc. of the crankshaft.
[0019]
Specifically, the larger of Equations (1) and (2) is calculated as a combustion state parameter, and when a predetermined misfire determination slice level determined by an operating state (engine speed, engine load, etc.) is exceeded, misfire occurs. Is determined. In addition, the misfire cylinder is basically discriminated from the phase of the peak value of the combustion state parameter exceeding the misfire determination slice level. On the other hand, in the equations (1) and (2), the phase of the misfire cylinder is determined. Because of the difference, the misfiring cylinder is determined including the magnitude relation between the equations (1) and (2).
[0020]
In a vehicle having an automatic transmission, when the vehicle is engaged (locked up), the peak value of the misfire signal tends to be small. Therefore, the misfire determination level is corrected depending on the presence or absence of the engaged state (up / down). I do.
[0021]
FIG. 8 shows a flowchart of the present invention. The process is performed for each ignition. In step 801, the window passing time Tw is measured. The window width W of the window passage time Tw measured here is 120 °. In step 802, the actual combustion state parameter D1A1 is calculated by equation (1), and in step 803, the remaining combustion state parameter D1A2 is calculated by equation (2). In step 804, the larger of the actual combustion state parameter D1A1 and the remaining combustion state parameter D1A2 is set as the combustion state parameter D1A. In steps 805 and 806, it is checked whether the previous value of the combustion state parameter D1A exceeds the misfire determination slice level and the previous value is a peak value. If it is determined in steps 805 and 806 that there is a misfire, in step 807, the actual combustion state parameter D1A1 and the remaining combustion state parameter D1A2 are compared. Based on the comparison result, in steps 808 and 809, the misfire cylinder is specified, and the misfire counter corresponding to the misfire cylinder is incremented. Step 808 is a case where the actual rotation fluctuation is dominant. At this time, the cylinder before one ignition of the ignition cylinder signal (CYLNOs) is set as the misfiring cylinder. Step 809 is the case where the remaining rotation fluctuation is dominant. At this time, the cylinder before the second ignition of the ignition cylinder signal (CYLNOs) is set as the misfiring cylinder. In the present embodiment, the ignition order is # 1 → # 6 → # 5 → # 4 → # 3 → # 2.
[0022]
Finally, for the next calculation, in step 810, the previous window passing time Tw is set to the value two times before, and the current window passing time Tw is set to the previous value. Further, the present combustion state parameter D1A is set to a previous value, the current actual combustion state parameter D1A1 is set to a previous value, and the current remaining combustion state parameter D1A2 is set to a previous value.
[0023]
FIG. 9 shows an example of the effect of the present invention. Conventionally, the region condition is 6000 r / min. In this region, conventionally, in this region, a misfire signal cannot be detected due to noise (crankshaft vibration, combustion fluctuation, etc.) or a misfire cylinder is erroneously determined even if a misfire signal can be detected. Was. FIG. 9A shows the result when the # 1 cylinder misfires. From the figure, it can be seen that the combustion state parameter becomes large at the time of misfire and misfire can be detected. Further, the remaining rotation fluctuation is dominant, the condition of step 809 is satisfied, and the misfire counter of the # 1 cylinder is incremented without erroneous cylinder determination (the same operation is performed for the # 3 cylinder, # 4 cylinder, and # 6 cylinder). Is shown).
[0024]
Next, FIG. 9B shows the result when the # 5 cylinder misfires. As in FIG. 9A, it can be seen that the combustion state parameter becomes large at the time of misfire and misfire can be detected. Further, in the case of # 5 cylinder misfire, the conditions of Steps 808 and 809 are satisfied, and as a result, the misfire counter is incremented only in # 5 cylinder without erroneous cylinder determination (similar operation for # 2 cylinder misfire). Is shown).
[0025]
As described above, in addition to obtaining the rotation fluctuation value due to the actual misfire, the remaining rotation fluctuation value due to the misfire is obtained. Further, the predetermined angle of the crankshaft for measuring the time signal is set such that the remaining rotation fluctuation value due to the misfire becomes larger than the actual rotation fluctuation value due to the misfire. The remaining rotation fluctuation value due to a misfire is more affected by the operating range (engine speed, engine load, etc.), crankshaft shaft vibration (torsion, eccentricity, etc.), combustion fluctuation, etc. than the rotation fluctuation value due to an actual misfire. Has difficult characteristics. However, depending on the misfiring cylinder, even if the predetermined angle of the crankshaft for measuring the time signal is changed as much as possible, the remaining rotational fluctuation value due to the misfire should be larger than the actual rotational fluctuation value due to the misfire. May not be possible. In this case, the misfire is detected from the rotation fluctuation value due to the actual misfire. Further, the misfire cylinder is specified by a misfire when the misfire is detected based on the remaining rotational fluctuation value due to the misfire and when the misfire is detected due to the actual rotational fluctuation value due to the misfire. Therefore, the misfiring cylinder is identified based on the deviation between the rotation fluctuation value due to the actual misfire and the remaining rotation fluctuation value due to the misfire.
[0026]
As described above, according to the present invention, even if the position of the misfire detection plate is located at a position that is easily affected by the shaft vibration (torsion, eccentricity, etc.) of the crankshaft, the combustion fluctuation, and the plate manufacturing error, A misfire can be accurately detected from the rotation to the high rotation region and the entire region.
[0027]
【The invention's effect】
Even if the misfire detection plate is located at a position that is easily affected by crankshaft shaft vibration (torsion, eccentricity, etc.), combustion fluctuations, and plate manufacturing errors, misfires can occur over the entire range from low rotation to high rotation. Can be accurately detected.
[Brief description of the drawings]
FIG. 1 is a block diagram of the present invention.
FIG. 2 is an example of an internal combustion engine system to which the present invention is applied.
FIG. 3 is a graph showing a change in rotation speed when a misfire occurs.
FIG. 4 shows a window passage time Tw at the time of misfire and an actual combustion state parameter D1A1 (window width = 90 °, 4000 r / min).
FIG. 5 shows a window passing time Tw (window width = 90 °) of 6000 r / min.
FIG. 6 is a window passing time Tw (window width = 120 °) at the time of misfire of # 1 cylinder of 4000 r / min.
FIG. 7 shows a window passage time Tw (window width = 120 °) of 6000 r / min.
FIG. 8 is a flowchart of the present invention.
FIG. 9 is an example of the effect of the present invention.
[Explanation of symbols]
101: time signal measuring means, 102: actual combustion state parameter calculating means, 103: residual combustion state parameter calculating means, 104: combustion state parameter calculating means,
105: combustion state determination means, 106: abnormal combustion cylinder determination means, 107: ignition cylinder signal calculation means, 200: air cleaner, 201: ignition device, 202: fuel injection device, 203: rotation speed detection means, 204: flow rate detection Means 205 Air-fuel ratio sensor 206 Catalyst 207 Internal combustion engine control device 208 Plate or ring gear 209 Fuel tank 210 Fuel pump 211 Pressure regulator 212 Fuel pipe 213 Throttle valve , 214 ... cylinders.

Claims (11)

In a detecting device for detecting a combustion state of an internal combustion engine from a time signal obtained by measuring an elapsed time during which a crankshaft rotates a predetermined angle, a means for calculating an actual combustion state parameter, a means for calculating a residual combustion state parameter, Combustion state parameter calculating means for calculating a combustion state parameter from the combustion state parameter and the remaining combustion state parameter; combustion state determining means for determining a combustion state from the combustion state parameter calculating means; and means for calculating an ignition cylinder signal Abnormal combustion cylinder determining means for determining an abnormal combustion cylinder based on at least one of the combustion state determining means, the actual combustion state parameter calculating means, the residual combustion state parameter calculating means, and the ignition cylinder signal. A combustion state detection device for an internal combustion engine, comprising: 2. The combustion state detecting device for an internal combustion engine according to claim 1, wherein the actual combustion state parameter calculating means is obtained based on a difference between the current ignition time and the previous ignition time of the time signal. 2. A combustion state detecting device for an internal combustion engine according to claim 1, wherein said remaining combustion state parameter calculating means is obtained based on a difference between said current time signal and said previous ignition time signal. 2. The internal combustion engine according to claim 1, wherein the combustion state parameter calculating means sets an addition value, a difference value, or a maximum value or a minimum value of the actual combustion state parameter and the remaining combustion state parameter as a combustion state parameter. Combustion state detection device. The actual combustion state parameter calculation means and the remaining combustion state parameter calculation means determine a detection rate of the actual combustion state parameter and the remaining combustion state parameter based on a set value of the predetermined angle of the crankshaft for measuring the time signal. 2. The combustion state detecting device for an internal combustion engine according to claim 1, wherein: 6. The internal combustion engine according to claim 5, wherein the set value of the predetermined angle of the crankshaft for measuring the time signal is set such that the remaining combustion state parameter is larger than the actual combustion state parameter. Combustion state detection device. 2. The combustion state detection device for an internal combustion engine according to claim 1, wherein the combustion state determination means determines that the combustion state is abnormal when the combustion state parameter exceeds a determination level. The abnormal combustion cylinder judging means includes an ignition cylinder signal when the combustion state judging means judges an abnormal state and detects a peak value of the combustion state parameter, the actual combustion state parameter, and the remaining combustion state parameter. The combustion state detection device for an internal combustion engine according to claim 1, wherein the determination is made based on a deviation of the combustion state. The combustion state detection device for an internal combustion engine according to claim 7, wherein the determination level is calculated based on an operation state and a load of the internal combustion engine. The apparatus according to claim 7, wherein the determination level is calculated based on an engine speed and an engine load. 8. The combustion state detecting device for an internal combustion engine according to claim 7, wherein the determination level is corrected according to an engagement state (lock-up state) of the automatic transmission.

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