JP3031469B2 - Ignition timing control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to an ignition timing control device for an internal combustion engine that advances and retards an ignition timing such that a crank angle position that gives a maximum in-cylinder pressure of each cylinder becomes an average crank angle position of all cylinders.

2. Description of the Related Art In general, in an internal combustion engine, the ignition timing is an important control target that affects the output and fuel efficiency of the internal combustion engine, and various control devices have been devised and adopted. By the way, in general, in a multi-cylinder internal combustion engine, (1) the amount of air taken into each cylinder is different due to complicated intake pipe shape, interference between the cylinders of the taken air, and the like. The combustion temperature is slightly different for each cylinder due to the influence of the cooling path of the cylinder, etc. (3) The production volume varies in the combustion chamber volume, piston shape, etc. of each cylinder, (4) Fuel due to the accuracy error of the injector, etc. Because the air-fuel ratio differs slightly for each cylinder due to the difference in injection amount, etc., the optimal air-fuel ratio and ignition timing differ for each cylinder, and in an internal combustion engine employing the same ignition timing for all cylinders, There is room for improving the variation in combustion between cylinders. In particular, in recent high-performance internal combustion engines, which tend to have high output and low fuel consumption, if there is a variation in combustion among the cylinders, this will have a large effect on output fluctuations, resulting in energy loss and unstable output. This not only causes a decrease in the total output of the engine, but also causes problems in measures against vibration and controllability of the air-fuel ratio. Note that Japanese Unexamined Patent Publication No. 59-120779 (hereinafter referred to as "first prior art")
In order to obtain the optimum ignition timing regardless of manufacturing variations and changes over time of the internal combustion engine, the in-cylinder pressure and crank angle of each cylinder were detected, and the in-cylinder pressure became maximum for each cylinder. Crank angle (maximum pressure crank angle) θpmax
And the pressure maximum crank angle θpmax is averaged for each cylinder to obtain an in-cylinder pressure maximum crank angle average value θin for each cylinder, and then the in-cylinder pressure maximum crank angle average value θin for each cylinder
, The average crank angle θm of all cylinders for all cylinders is calculated, the ignition timing correction amount α is set according to the average crank angle θm of all cylinders, and the basic ignition timing A set based on the operating range of the internal combustion engine is ignited. There is disclosed a technique of setting an ignition timing A ′ for an internal combustion engine by correcting the ignition timing A ′ with a timing correction amount α. In Japanese Patent Application Laid-Open No. 59-201972 (hereinafter referred to as "second prior art"), there is a difference in generated torque between cylinders due to slight variations among cylinders such as an air-fuel ratio, an ignition timing, and a compression ratio. In order to suppress the difference in engine rotation speed between cylinders during idle operation due to this, to stabilize idle rotation and prevent engine vibration, the engine rotation during the expansion stroke (combustion stroke) for each cylinder during idle operation The engine speed is detected, the engine speed is averaged for each cylinder to obtain an average rotational speed NEi for each cylinder, and then the average rotational speed NEall for all cylinders is calculated from the average rotational speed NEi for each cylinder. For cylinders having a higher average cylinder speed NEi than the average cylinder speed NEall, the ignition timing is retarded, and for cylinders having a lower average cylinder speed NEi with respect to the average cylinder speed NEall, the ignition timing is reduced. Advanced technology is disclosed a time.

[Problems to be solved by the invention]

However, in the first prior art, the ignition timing is uniformly corrected for all cylinders by the ignition timing correction amount α set according to the average crank angle θm of all cylinders. It is not possible to suppress the variation in combustion for each cylinder due to the difference in the angular position. For this reason, in the first prior art, the output performance and the fuel consumption deteriorate, and the total output of the internal combustion engine is reduced due to the variation in the combustion in each cylinder due to the difference in the maximum in-cylinder pressure crank angle position in each cylinder. There are inconveniences such as lowering and engine vibration. In the second prior example, the ignition timing is corrected by using the engine rotation speed in the expansion stroke (combustion stroke) of each cylinder as a factor. However, the engine rotation speed in the expansion stroke (combustion stroke) is: It merely indirectly indicates the quality of the combustion state for each cylinder, and cannot accurately determine the difference in the maximum in-cylinder pressure crank angle position for each cylinder. Therefore, it is not possible to reliably suppress the variation in combustion in each cylinder due to the difference in the maximum in-cylinder pressure crank angle position in each cylinder. In addition, as the engine speed increases, the combustion stroke cycle of each cylinder becomes shorter, the engine speed in the expansion stroke of each cylinder is moderated, and the effect of noise increases, so that the engine is excluded from idling. In the engine operating region, it is not possible to grasp the variation in combustion for each cylinder from the engine speed during the expansion stroke (combustion stroke). For this reason, the second prior art is applicable only at the time of idling operation. In addition, the variation in combustion of each cylinder due to the difference in the maximum in-cylinder pressure crank angle position of each cylinder is reduced by the entire internal combustion engine. It cannot be suppressed over the operating range. As a result, in a region where engine output is required, the output performance and fuel efficiency are deteriorated, and the total output of the internal combustion engine is reduced.Also, even when the engine is idling, the difference in the maximum in-cylinder pressure crank angle position for each cylinder is caused. Since it is not possible to reliably suppress the variation in combustion between the cylinders, it is possible to sufficiently suppress the engine vibration caused by the variation in combustion between the cylinders due to the difference in the crank angle indicating the maximum in-cylinder pressure for each cylinder. There are inconveniences that cannot be made. In view of the above circumstances, the present invention reliably suppresses variation in combustion of each cylinder due to a difference in the maximum in-cylinder pressure crank angle position for each cylinder over the entire operation range of the internal combustion engine, and achieves output performance and total output of the internal combustion engine. It is an object of the present invention to provide an ignition timing control device for an internal combustion engine which is improved in output and fuel consumption, is excellent in silence, and is suitable for a high-performance internal combustion engine.

[Means for Solving the Problems]

In order to achieve the above object, the present invention calculates a cylinder pressure maximum crank angle average value for each cylinder by averaging a crank angle indicating a cylinder pressure maximum value detected for each cylinder, and calculates a cylinder pressure maximum crank angle for each cylinder. The average crank angle of all cylinders for all cylinders is obtained from the angle average value, and the basic ignition timing set based on the operating range of the internal combustion engine is corrected by the ignition timing correction amount set in accordance with the average cylinder angle of all cylinders to obtain the internal combustion. In an ignition timing control device for an internal combustion engine that sets an ignition timing for an engine, the cylinder pressure maximum average crank angle for each cylinder is compared with the average crank angle for all cylinders, and the average crank angle for all cylinders is determined for each cylinder. The ignition timing of the cylinder is advanced by correcting the ignition timing of the cylinder whose cylinder average cylinder pressure average value is retarded, and the cylinder ignition timing of each cylinder is advanced by the cylinder pressure maximum crank angle average value of each cylinder. Cylinder-by-cylinder ignition timing correction amount calculating means for calculating a cylinder-by-cylinder ignition timing correction amount for retarding the cylinder ignition timing, and cylinder-by-cylinder ignition timing correction based on the basic ignition timing set based on the operating range of the internal combustion engine. And ignition timing calculation means for calculating the ignition timing for the internal combustion engine for each cylinder, correcting the ignition timing for each cylinder, and making the crank angle indicating the maximum value of the in-cylinder pressure of each cylinder substantially the same for all cylinders.

[Action]

In the present invention, the crank angle indicating the maximum value of the in-cylinder pressure detected for each cylinder is averaged to calculate the average value of the maximum in-cylinder pressure crank angle for each cylinder. Find the average crank angle of all cylinders for the cylinder. Then, the cylinder pressure maximum crank angle average value for each cylinder is compared with the all cylinder average crank angle, and the cylinder pressure maximum crank angle average value for each cylinder is retarded with respect to the all cylinder average crank angle. Calculates the ignition timing correction amount for each cylinder for advancing the ignition timing of the cylinder, and for the cylinder in which the average value of the maximum in-cylinder pressure crank angle for each cylinder is advanced, the ignition timing correction amount for the cylinder is corrected to retard the ignition timing of the cylinder. I do. Then, the basic ignition timing set based on the operation range of the internal combustion engine is corrected by the ignition timing correction amount for each cylinder, the ignition timing for the internal combustion engine is calculated for each cylinder, and the crank angle indicating the maximum value of the in-cylinder pressure of each cylinder is calculated. Substantially match for all cylinders.

【Example】

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 shows an embodiment of the present invention, FIG. 1 is a schematic view of an essential part of an engine, FIG. 2 is a schematic plan view of an engine, FIG. 3 is a sectional view taken along line III-III of FIG. Is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is a block diagram showing a functional configuration of the control device,
6 is an explanatory diagram of an ignition timing map, FIG. 7 is a diagram of a maximum in-cylinder pressure curve based on an ignition timing and a crank angle, and FIG. 8 is a flowchart showing an ignition timing control procedure in a control device. Reference numeral 1 in FIGS. 1 and 2 denotes a horizontally opposed four-cylinder engine as an example of an internal combustion engine, in which a cylinder block 2 has left and right sides (LH, R) around a crankshaft 3.
H) The bank is divided into two. Each piston 4 inserted into each of the cylinders 2a, 2b, 2c, 2d provided in the LH bank and the RH bank of the cylinder block 2 is connected to the crankshaft 3 via a connecting rod 4a. In addition, the combustion chambers 6a, 6b, 6 are provided in portions surrounded by the pistons 4 and the cylinder heads 5a, 5b of the cylinders 2a to 2d.
c and 6d are formed respectively. An in-cylinder pressure sensor 7 is mounted and fixed at a position corresponding to each of the cylinders 2a to 2d of each of the cylinder heads 5a and 5b via an adapter 8, and as shown in FIGS. The tip detecting portion of the internal pressure sensor 7 faces each of the combustion chambers 6a to 6d. The in-cylinder pressure sensor 7 has cylinder heads 5a and 5b.
It may be directly fixed to the surface. Further, each cylinder head 5a, 5b has a respective cylinder 2a-2d.
Are mounted. In addition, the intake ports 1a communicating with the combustion chambers 6a to 6d respectively,
Each of the injectors 10 is provided, and the upstream side of each intake port 1a is communicated via the intake manifold 1 to a throttle chamber 14 in which a throttle valve 13 is interposed. The upstream side of the throttle chamber 14 is connected to an intake pipe 15 and a heating wire. The air flow meter 16 communicates with an air cleaner 17 via a main passage 16a. The air flow meter 16 is provided with a sub-passage 16b that bypasses the main passage 16a.
A hot wire 16d and a temperature compensation plug 16e, which constitute a part of a bridge circuit provided in the controller 16c, are exposed. The air flow meter 16 measures a mass flow rate of intake air flowing through the auxiliary passage 16b, that is, an intake air amount Q, and outputs a measurement signal from the controller 16c. The crankshaft 3 is provided with a crank angle sensor 18 for detecting the engine speed N and the crank angle Crθ. Further, a throttle sensor 19 for detecting the throttle opening θ is connected to the throttle valve 13. On the other hand, reference numeral 20 denotes a control device, and the sensors 7, 16, 18, and 19 are connected to the input side, the injectors 10 are connected to the output side, and the ignition plugs 9 are installed independently. The ignition coil 21 is connected through the connection. Next, a functional configuration of the control device 20 will be described with reference to FIG. The control device 20 includes basic ignition timing setting means 22, cylinder-specific crank angle detecting means 23 for detecting the crank angle indicating the maximum in-cylinder pressure for each cylinder, counter means 24, cylinder-specific average crank angle calculating means 25, and average for all cylinders. It has the functions of crank angle calculation means 26, cylinder-specific ignition timing correction amount calculation means 27, ignition timing calculation means 28, and drive means 29. The basic ignition timing setting means 22 determines a backup RAM from the intake air amount Q by the air flow meter 16 and the engine speed N by the crank angle sensor 18 as the engine operation state.
Ignition timing map for each cylinder stored in storage means such as
The MP IG is searched, and the ignition timing IGT * written in the current operation area (grid point of the map) is read and set as the basic ignition timing. The ignition timing map MP IG is provided for each cylinder. As shown in FIG. 6, the ignition timing map MP IG ignites each grid point composed of an intake air amount Q grid and an engine speed N grid. The latest ignition timing IGT calculated by the timing calculation means 28 is sequentially written. Further, the cylinder-specific crank angle detecting means 23 is provided for each of the cylinders 2a to 2d.
From the output signal of the in-cylinder pressure sensor 7 and the crank angle signal Crθ of the crank angle sensor 18, a crank angle θPMAX indicating the maximum value PMAX of the in-cylinder pressure for each cycle is detected for each cylinder. θPMAX is stored in a grid point (operating region) specified by the engine speed N grid and the intake air quantity Q grid in the storage means. The counter means 24 counts the crank angle θPMAX stored at the same grid point (operating region) for a predetermined cycle (τ0). If the number of crank angles θPMAX1... ΘPMAXn detected and stored by the cylinder-specific crank angle detection means 23 exceeds a predetermined cycle (τ0) by the counter means 24, Are averaged to calculate the cylinder pressure maximum crank angle average value θPMAXAV for each cylinder. The all-cylinder average crank angle calculation means 26 averages the in-cylinder pressure maximum crank angle average value θPMAXAV for each cylinder for all cylinders, and calculates an all-cylinder average crank angle XAV for all cylinders. The cylinder-by-cylinder ignition timing correction amount calculating means 27 calculates, for each cylinder, the absolute value Δθ of the difference between the cylinder-internal maximum cylinder crank angle average θPMAXAV and the cylinder-by-cylinder average crank angle XAV (Δθ = | XAV−θPMAXAV | ). Then, the absolute value Δθ of the difference for each cylinder is compared with a reference value ΔD set in advance according to the engine operating region determined by the engine speed N and the intake air amount Q, and the deviation is obtained. Accordingly, the ignition timing correction amount ΔIg for the corresponding cylinder is calculated (see FIG. 7). That is, when Δθ ≦ ΔD, the deviation of the in-cylinder pressure maximum crank angle average value θPMAXAV of each cylinder with respect to the all cylinder average crank angle XAV is within a dead zone defined by the reference value ΔD, and the crank angle of the corresponding cylinder indicates the maximum in-cylinder pressure value. Average value θPMAX
When AV substantially coincides with the average crank angle XAV of all cylinders, the current ignition timing correction amount ΔIg for the corresponding cylinder is held as it is (ΔIg = ΔIg). On the other hand, if Δθ> ΔD and the deviation of the maximum in-cylinder pressure average crank angle θPMAXAV of each cylinder with respect to the all-cylinder average crank angle XAV deviates from the dead zone defined by the reference value ΔD, the maximum in-cylinder pressure crank angle for each cylinder Average value θPMAX
AV is compared with an average crank angle XAV of all cylinders. And
For cylinders in which the maximum cylinder pressure maximum crank angle average θPMAXAV for each cylinder is retarded with respect to the average cylinder angle XAV for all cylinders when θPMAXAV> XAV, the maximum cylinder angle maximum cylinder angle pressure for the corresponding cylinder relative to the average cylinder angle XAV for all cylinders Advance angle correction amount α according to the deviation between absolute value Δθ of difference of θPMAXAV and reference value ΔD
(Α> 0) is calculated, and the advance correction amount α is added to the current ignition timing correction amount ΔIg for the corresponding cylinder stored in the map for each cylinder according to the operation region, and the ignition timing correction amount for the relevant cylinder is calculated. Update ΔIg (ΔIg = ΔIg + α). When θPMAXAV <XAV, the average crank angle XAV of all cylinders
On the other hand, for cylinders with advanced cylinder pressure maximum crank angle average value θPMAXAV for each cylinder, all cylinder average crank angle X
Maximum in-cylinder pressure crank angle average θPM of the corresponding cylinder with respect to AV
Calculate the retardation correction amount β (β <0) according to the difference between the absolute value Δθ of the difference of AXAV and the reference value ΔD, and add the retardation correction amount β to the current ignition timing correction amount ΔIg for the relevant cylinder. Then, the ignition timing correction amount ΔIg for the corresponding cylinder is updated (ΔIg = Δ
Ig + β). Then, the ignition timing calculating means 28 calculates the basic ignition timing IGT * set by the basic ignition timing setting means 22 based on the operating region of the engine and calculates the cylinder-specific ignition timing correction amount calculated by the cylinder-specific ignition timing correction amount calculating means 27. The ignition timing IGT for the engine 1 is calculated for each cylinder by correcting with the amount ΔIg. Accordingly, for a cylinder in which the maximum in-cylinder pressure average crank angle θPMAXAV of each cylinder is retarded with respect to the average cylinder angle XAV of all cylinders, the ignition timing of the cylinder is adjusted by the advance correction amount α according to the retard amount. For the cylinders in which the cylinder-specific maximum cylinder crank angle average value θPMAXAV is advanced, the ignition timing of the cylinder is retarded by the retard correction amount β in accordance with the advance amount. Thus, the crank angle indicating the maximum value of the in-cylinder pressure of each cylinder can be made substantially the same for all cylinders, and the variation in combustion in each cylinder can be accurately suppressed over the entire region. Further, the ignition timing calculating means 28 calculates the N grid and the Q of the ignition timing map MP IG provided for each cylinder.
The ignition timing stored at the grid point (operating region) determined by the grid is sequentially updated with the latest ignition timing IGT calculated for each cylinder. And for the spark plug 9,
Latest ignition timing I stored in ignition timing map MP IG
The operating range (grid point) is specified and taken in from the engine speed N and the intake air amount Q, and a signal based on the ignition timing IGT is output to the ignition coil 21 via the driving means 29. A high voltage is generated on the secondary side of 21, and this voltage is applied to the spark plug 9 of each cylinder to ignite. Next, the ignition timing control procedure by the control device 20 will be described with reference to the flowchart of FIG. First, in step S101, the crank angle indicating the maximum value PMAX of the in-cylinder pressure for each cycle is obtained from the output signal of the in-cylinder pressure sensor 7 provided in each of the cylinders 2a to 2d and the crank angle signal Crθ of the crank angle sensor 18. θPMAX is detected for each cylinder,
The data is stored in a corresponding grid point (operating area) specified by the engine speed N and the intake air amount Q in a map provided for each cylinder in a storage means such as a backup RAM. Then, in step S102, a count value τ representing the number of stored crank angles θPMAX in the same operation region is counted up, and in the following step S103, the count value τ is reduced to a predetermined value τ
0, it is determined whether or not the crank angle θPMAX stored at the same grid point (operating region) has reached a predetermined cycle (τ0). If τ <τ0, the process returns to step S101.
The processing for detecting and storing the crank angle θPMAX is performed again. Then, when τ ≧ τ0 and the accumulated number of crank angles θPMAX reaches a predetermined cycle (τ0), the process proceeds to step S104, and the process proceeds to step S104 for the predetermined cycle (cylinder point) for each cylinder stored in the operation region (lattice point) of the map. τ0) crank angle θPM
AX is averaged, and the maximum in-cylinder pressure crank angle average θPMAXAV
Is calculated for each cylinder. Next, in step S105, the in-cylinder pressure maximum crank angle average value θPMAXAV obtained for each cylinder is summed and averaged for all cylinders to calculate an average all-cylinder crank angle XAV for all cylinders. Crank angle XAV
Cylinder maximum cylinder angle average value θPMAXAV
Is calculated for each cylinder (Δθ =
| XAV-θPMAXAV |), and proceeds to step S107. In step S107, the absolute value of the difference Δθ for each cylinder is compared with a reference value ΔD set in advance according to the engine operating range determined by the engine speed N and the intake air amount Q. When Δθ ≦ ΔD, the average crank angle XAV of all cylinders
Cylinder maximum cylinder angle average value θPMAXAV
Is within a dead zone defined by the reference value ΔD,
Average crank angle θPM indicating the maximum value of the in-cylinder pressure of the corresponding cylinder
When AXAV is substantially equal to the average crank angle XAV of all cylinders, the current ignition timing correction amount ΔIg for the relevant cylinder is held as it is, and the ignition timing IGT stored in the relevant operation area of the ignition timing map MP IG is maintained. Jumps to step S113 without correcting the value, clears the count value τ (τ = 0), and exits the routine. If Δθ> ΔD and the deviation of the maximum in-cylinder pressure maximum crank angle θPMAXAV of each cylinder with respect to the average crank angle XAV of all cylinders deviates from the dead zone defined by the reference value ΔD, the process proceeds to step S108, and the process proceeds to step S108. The in-cylinder pressure maximum crank angle average value θPMAXAV is compared with the all-cylinder average crank angle XAV. When θPMAXAV> XAV, the process proceeds from step S108 to step S109, and for cylinders in which the cylinder-specific maximum cylinder pressure average value θPMAXAV for each cylinder is retarded with respect to the all cylinder average crank angle XAV, the absolute value of the difference Δθ And reference value ΔD
And calculates the advance correction amount α (α> 0) corresponding to the deviation from the current ignition timing correction amount ΔIg for the corresponding cylinder stored in the map for each cylinder in accordance with the operation region, and calculates the advance correction amount α. Then, the ignition timing correction amount ΔIg for the corresponding cylinder is updated (ΔIg = ΔIg + α). When θPMAXAV <XAV, the process proceeds to step S110, and for the cylinder in which the cylinder-specific maximum cylinder angle average value θPMAXAV for each cylinder is advanced with respect to the all-cylinder average crank angle XAV, the absolute value of the difference Δθ and the reference value The retardation correction amount β (β <0) according to the deviation from ΔD is calculated, the retardation correction amount β is added to the current ignition timing correction amount ΔIg for the relevant cylinder, and the ignition timing correction amount ΔIg for the relevant cylinder is calculated. Is updated (ΔIg = Δ
Ig + β). Next, in step S111, the ignition timing IGT stored in the corresponding operation area of the ignition timing map MP IG is read,
This is set as the basic ignition timing IGT *, and the basic ignition timing IGT * is corrected by the cylinder-by-cylinder ignition timing correction amount ΔIg calculated in step S109 or step S110, and the ignition timing IGT for the engine 1 is calculated for each cylinder. (IGT = IGT * + ΔIg). Then, in step S112, the ignition timing IGT stored in the corresponding region of the corresponding ignition timing map MPIG provided for each cylinder is updated with the latest ignition timing IGT calculated in step S111. Clear the value τ and exit the routine.

【The invention's effect】

As described above, according to the present invention, the crank angle indicating the maximum value of the in-cylinder pressure detected for each cylinder is averaged to calculate the average value of the maximum in-cylinder pressure crank angle for each cylinder. Since the average crank angle of all cylinders for all cylinders is obtained from the average value of the maximum crank angle, and the average value of the maximum in-cylinder pressure for each cylinder is compared with the average crank angle of all cylinders, the combustion state of each cylinder can be directly determined. With the indicated in-cylinder pressure, it is possible to accurately grasp the variation in combustion in each cylinder due to the difference in the maximum in-cylinder pressure crank angle position in each cylinder over the entire operation range of the internal combustion engine. Then, for cylinders in which the average cylinder pressure maximum crank angle average value of each cylinder is retarded with respect to the average cylinder angle of all cylinders, the ignition timing of the cylinder is advanced and corrected. For the cylinder in which the average in-cylinder pressure maximum crank angle average value is advanced, the ignition timing correction amount for each cylinder for retarding the ignition timing of the cylinder is calculated. Then, the basic ignition timing set based on the operation range of the internal combustion engine is corrected by the ignition timing correction amount for each cylinder, the ignition timing for the internal combustion engine is calculated for each cylinder, and the crank indicating the maximum value of the in-cylinder pressure of each cylinder is calculated. Since the angles are substantially the same for all cylinders, the ignition timing is directly advanced and retarded in accordance with the difference in the maximum in-cylinder pressure crank angle position for each cylinder over the entire operation range of the internal combustion engine, thereby directly and reliably. In addition, it is possible to suppress a difference in the maximum in-cylinder pressure crank angle position for each cylinder. Therefore, it is possible to appropriately and reliably suppress the variation in combustion in each cylinder due to the difference in the maximum in-cylinder pressure crank angle position in each cylinder over the entire operation range of the internal combustion engine. Then, over the entire operation range of the internal combustion engine, the variation in combustion between the cylinders due to the difference in the maximum in-cylinder pressure crank angle position for each cylinder is reliably suppressed, so that even in a region where engine output is required, the combustion is stable. As a result, improved output performance, improved fuel efficiency, and improved total output of the internal combustion engine can be realized. Further, over the entire operation range of the internal combustion engine, it is possible to suppress engine vibration caused by combustion variation between cylinders due to a difference in crank angle indicating the maximum in-cylinder pressure for each cylinder, and to reduce the engine quietness. Can be improved. Further, the optimum ignition timing suitable for a high-performance internal combustion engine can be controlled for each cylinder over the entire operation range of the internal combustion engine, and the ignition timing controllability can be improved.

[Brief description of the drawings]

1 shows an embodiment of the present invention, FIG. 1 is a schematic view of an essential part of an engine, FIG. 2 is a schematic plan view of an engine, FIG. 3 is a sectional view taken along line III-III of FIG. Fig. 5 is a sectional view taken along line IV-IV in Fig. 3, Fig. 5 is a block diagram showing a functional configuration of the control device, Fig. 6 is an explanatory diagram of an ignition timing map, and Fig. 7 is a maximum in-cylinder pressure based on ignition timing and crank angle. FIG. 8 is a flowchart showing an ignition timing control procedure in the control device. Reference Signs List 1 engine (internal combustion engine) 2a to 2d cylinder 7 cylinder pressure sensor 9 spark plug 18 crank angle sensor 20 control device 27 cylinder-specific ignition timing correction amount calculation means 28 Ignition timing calculation means

Claims (1)

(57) [Claims] A crank angle indicating a maximum value of an in-cylinder pressure detected for each cylinder is averaged to calculate an average value of a maximum crank angle of an in-cylinder pressure for each cylinder. The ignition timing for the internal combustion engine is set by correcting the basic ignition timing set based on the operating range of the internal combustion engine with the ignition timing correction amount set in accordance with the average cylinder angle for all cylinders. In the ignition timing control device for an internal combustion engine, the average cylinder pressure maximum crank angle for each cylinder is compared with the average cylinder angle for all cylinders, and the average cylinder pressure maximum crank angle for each cylinder is compared with the average cylinder angle for all cylinders. For a cylinder whose value is retarded, the ignition timing of the cylinder is advanced and corrected. For a cylinder whose cylinder-specific maximum cylinder pressure average value is advanced, the ignition timing of the cylinder is retarded. A cylinder-specific ignition timing correction amount calculating means for calculating a correct cylinder-specific ignition timing correction amount; and correcting the basic ignition timing set based on the operating region of the internal combustion engine with the cylinder-specific ignition timing correction amount, for the internal combustion engine. An ignition timing control device for an internal combustion engine, comprising: ignition timing calculation means for calculating an ignition timing for each cylinder and making a crank angle indicating a maximum value of the in-cylinder pressure of each cylinder substantially coincide with each other.