JP2000352348A - Cylinder discrimination unit for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a sensor for cam shaft by enabling cylinder discrimination only with crank angle signal generation means and provide a cylinder discrimination unit having better accuracy than a system to discriminate a cylinder only with a can shaft for an internal combustion engine. SOLUTION: In a four-cycle internal combustion engine having an odd number of cylinders such as a single cylinder, three cylinders, five cylinders and the like, a cylinder discrimination unit comprises means 10a, 10b to generate predetermined crank angle signals corresponding to each cylinder per revolution of a crankshaft of an internal combustion engine. The cylinder discrimination unit further comprises a means to detect rotational movement of the crankshaft and a cylinder discrimination means to discriminate a stroke of each cylinder based on the crank angle signals and the rotational movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder discrimination signal used for various engine controls such as ignition timing control and fuel injection timing control for each cylinder based on a reference crank angle in an internal combustion engine having an odd number of cylinders such as 1 or 3. The present invention relates to a cylinder discriminating device for an internal combustion engine that outputs a signal.

[0002]

2. Description of the Related Art In a four-cycle internal combustion engine, an intake process, a compression process, a combustion process, and an exhaust process are sequentially performed by two rotations of a crankshaft. Steps and an exhaust step are performed. In order to control ignition timing and fuel injection for each cylinder,
Conventionally, a signal detected from a camshaft that rotates at a ratio of 1/2 with respect to the rotation of a crankshaft is used to generate a cylinder determination signal for determining which process the cylinder is in. . That is, the detection of camshaft rotation is 4
This is because in a cycle internal combustion engine, two rotations and one cycle are performed, and cylinder discrimination cannot be performed simply by a crank angle signal alone, and ignition timing and fuel injection control cannot be performed for each cylinder.

However, since the camshaft is driven from the crankshaft by a belt or the like, a phase shift occurs between the camshaft and the crankshaft due to the operating state of the engine or the slack of the belt, and the detection angle accuracy is poor. There are cases. Further, in order to improve accuracy, there is a method of detecting a reference angle based on a crank angle and comparing the signal with a camshaft signal to determine a cylinder. However, in this case, at least one angle detection sensor is required for each of the crankshaft and the camshaft, so that the number of sensors cannot be reduced and the cost is hardly reduced (for example, Japanese Patent Application Laid-Open No. 3-172558; 3-17255
9, 3-168346, 3-172560, 3-
172561 etc.).

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and the cylinder discrimination can be performed only by the crank angle signal generating means, thereby eliminating the need for a camshaft sensor. It is an object of the present invention to provide a cylinder discriminating apparatus for an internal combustion engine which is capable of performing cylinder discrimination using only a camshaft and has high accuracy.

[0005]

The present invention has the following arrangement to achieve the above object. In a four-cycle internal combustion engine having an odd number of cylinders, such as a single cylinder, three cylinders, or five cylinders, a predetermined crank angle signal corresponding to each cylinder is provided for each rotation of a crankshaft of the internal combustion engine. Generating means, means for detecting rotation fluctuation of the crankshaft, and cylinder discriminating means for discriminating a process of each cylinder based on the crank angle signal and rotation fluctuation. It is a discriminating device. According to a second aspect of the present invention, there is provided a cylinder discriminating apparatus for an internal combustion engine according to the first aspect, wherein a rotation fluctuation in a crank angle region where the rotation fluctuation appears remarkably is detected and a cylinder is determined from the detected fluctuation amount. It is. The invention according to claim 3 is characterized in that the cylinder discrimination is performed by comparing the average rotation speed in the crank angle region where the rotation fluctuation has a mountain shape with the average rotation speed in the same angle region one rotation before. 2. A cylinder discriminating apparatus for an internal combustion engine according to claim 1. The invention according to claim 4 is the cylinder discriminating apparatus for an internal combustion engine according to claim 2 or 3, further comprising means for performing discrimination of the cylinder a plurality of times and completing the discrimination when the discrimination results match. . According to a fifth aspect of the present invention, the cylinder determination according to the second aspect and the cylinder determination according to the third aspect are both performed, and the determination is completed when both determination results match. A cylinder discriminating device for an internal combustion engine. The invention according to claim 6 is characterized in that the cylinder discrimination is performed in a predetermined low rotation speed range of the internal combustion engine, while the determination result in the low rotation speed range is used in a high rotation speed range. The cylinder discriminating apparatus for an internal combustion engine according to any one of the above. The invention according to claim 7 is characterized in that cylinder discrimination is performed at a predetermined throttle opening and a predetermined boost pressure.
The cylinder discriminating apparatus for an internal combustion engine according to any one of the above. The invention according to claim 8 is the cylinder discriminating apparatus for an internal combustion engine according to any one of claims 1 to 7, wherein the cylinder discrimination is not performed during ignition or injection cut. According to a ninth aspect of the present invention, the useless fire cut of ignition is performed for one cylinder based on the discrimination signal of the cylinder. The cylinder discriminating apparatus for an internal combustion engine according to any one of claims 1 to 8, wherein the cylinder-by-cylinder control is performed.

According to the present invention, in a four-cycle internal combustion engine having an odd number of cylinders, a predetermined crank angle signal corresponding to each cylinder is generated for each rotation of the crankshaft of the internal combustion engine, and the rotation fluctuation of the crankshaft is changed. And the process of each cylinder is determined based on the crank angle signal and the rotation fluctuation. Therefore, the cylinder discrimination (cylinder process discrimination) can be performed only by the crank angle signal generating means, so that a camshaft sensor is not required, and the accuracy is higher than that of the cylinder discrimination using only the camshaft. . In addition, it is possible to improve the poor accuracy due to the operating state and the slack of the belt when only the camshaft is used. Further, in the present invention, rotation fluctuations in a crank angle region where rotation fluctuations appear remarkably are detected, and cylinder discrimination is performed based on the detected fluctuation amounts. That is, rotation fluctuations are detected by comparing the rotational speeds before and after the adjacent top dead center (compression top dead center, exhaust top dead center) of each cylinder. In order to detect the rotation fluctuation in the angle range where the rotation fluctuation appears remarkably, for example, from the BTDC (before top dead center) 45 ° of the # 1 cylinder, the BTDC5
° and the BTDC45 of the adjacent # 2 cylinder
By comparing the degrees, it is possible to detect the rotation fluctuation due to the combustion stroke of the # 1 cylinder and the rotation fluctuation due to the compression stroke of the # 2 cylinder for each rotation in that section. This angle range is an angle range in which a clear rotation fluctuation (up and down) can be detected, and it is possible to accurately determine whether the combustion stroke or the compression stroke, and to determine the cylinder based on the relationship with the phase of the crank angle sensor signal. . The area before and after top dead center is an effective angle range as a basic angle signal for ignition, and the same signal can be used.

Further, in the present invention, the cylinder discrimination can be performed by comparing the average rotation speed in the crank angle region where the rotation fluctuation becomes a mountain shape with the average rotation speed in the same angle region one rotation before. If the average rotation speed before and after the top dead center is detected, in the case of an internal combustion engine having an odd number of cylinders, a section between a peak and a valley is detected every rotation, and the rotation speed is determined by comparing these average rotation speeds. Fluctuations can be detected. For example, the angle range before and after the compression top dead center becomes a valley of rotation fluctuation, and the same angle after one rotation becomes the exhaust top dead center and a hill of rotation fluctuation. By comparing the average rotation speed before one rotation, the stroke can be accurately determined. In addition, it is sufficient to calculate only the average number of rotations between the same angles for each rotation, so that it is possible to determine even a small reference angle signal and the calculation is easy. Further, it is possible to determine even with a small reference angle signal.

In the present invention, the determination of the cylinder is performed a plurality of times, and when the determination results match, the determination can be completed. Thereby, temporary load fluctuation and erroneous determination at the time of acceleration / deceleration are prevented, and accuracy is improved. Further, in the present invention, both the cylinder determination according to the second aspect and the cylinder determination according to the third aspect are performed, and the determination can be completed when both determination results match, thereby improving the accuracy. I do. Further, in the present invention, the cylinder discrimination is performed in a predetermined low rotation range of the internal combustion engine, while the determination result in the low rotation range can be used in a high rotation range. Rotational fluctuations are easy to discern and accuracy is high. Since the calculation does not need to be performed in a high rotation range where the rotation cycle is fast, the processing speed can be reduced and an inexpensive processor can be configured. The cylinder discrimination can be performed also during cranking. Further, in the present invention, cylinder discrimination can be performed at a predetermined throttle opening and a predetermined boost pressure. For example, during acceleration and deceleration, there may be cases where the rotation is different from the steady-state rotation fluctuation, and it may not be executed to improve accuracy. Further, in the present invention, the cylinder discrimination may not be performed during ignition or injection cut. That is,
At the time of ignition and injection cut, the rotation is different from the steady-state rotation fluctuation. Further, in the present invention, based on the cylinder discrimination signal, the useless fire cut is performed for one cylinder, and when the rotation fluctuation does not occur as a result of the useless fire cut, the useless fire cut control or the like for other cylinders is performed. Cylinder-by-cylinder control can be performed.
If there is no abnormality in the check, the unnecessary fire cut of the other cylinder and the other cylinder-specific control are performed. Thereby, for example, even in the event of an erroneous determination, engine stall can be prevented, and the determination can be performed again.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. In the four-stroke three-cylinder engine (internal combustion engine), the cylinder discriminating apparatus according to the embodiment detects a reference angle from a signal of a crank angle detector 10 of a crankshaft, detects rotation fluctuation, and discriminates a cylinder process (cylinder process). Discrimination).

FIGS. 1 and 2 are timing charts showing the timing of a four-cycle three-cylinder engine according to the first embodiment and examples of the configuration of a crank angle detector. FIGS. 3 and 4 are flowcharts showing the procedure of cylinder discrimination. is there. FIG.
FIG. 2 is a block diagram showing the entire control system of the engine, which is common to each embodiment (Embodiments 1 to 3).

As shown in FIG. 5, in this control system, each detector (each sensor) includes a crank angle detector 10 (engine speed detector), a throttle opening detector 12, an intake pressure detector. 14, an atmospheric pressure detector 16, an intake air temperature detector 18, an engine temperature detector (cooling water temperature detector) 20, and an engine inclination angle detector 22 are provided as necessary. The signals from the heater 10 and the engine temperature detector 20 are input into the processing device 24. The processing device 24 can perform desired processing with appropriate software using a general-purpose or custom-made microcomputer unit.

In the processing unit 24, those signals are input to the central processing unit (CPU) 28 via an input circuit (input interface) 26. The central processing unit 28 can input and output signals to and from an external communication device 30, and the signals are input and output to and from the central processing unit 28 via the communication interface 32. In the central processing unit 28, a random access memory (RAM) and a read only memory (ROM) are mounted, and a memory 30 such as an EEPROM (erasable / writable ROM) is provided separately. The signal of the central processing unit 28 outputs, via an output circuit 32, an operation signal of an injector 34, an air amount adjustment actuator 36, each display device 38, a fuel pump 40, and an ignition coil 42. An ignition signal is output to the ignition coil 42 via an ignition device 44 and a power supply device 46 to control ignition advance and retard.

1 and 2 show various examples of the configuration of the crank angle detector 10. FIG. Note that another configuration may be used as long as a crank angle signal can be obtained for each cylinder. The crank angle detector 10 shown in FIG. 1 and FIG. 2A has a detection sensor body 10a such as one hall sensor or proximity sensor, and
Rotor 4 for the detector that rotates while being fixed to the crankshaft
In FIG. 8, three cylinders are located at positions corresponding to specific crank angles of three cylinders (a first reference angle and a second reference angle are provided for each of the three cylinders).
There are two strikers 10b. Thus, each detection sensor body 10a is configured to generate a signal in the compression stroke of each cylinder and the exhaust stroke after one rotation thereof, and to obtain a signal for discriminating the cylinder.

A crank angle detector 1 shown in FIG.
In the case of 0, 3 is set at a position corresponding to a specific crank angle of three cylinders (a first reference angle and a second reference angle are provided for each of the three cylinders).
In addition to having three detection sensor bodies 10a, the rotor 48 for detection is provided with one striker 10b at a position corresponding to the first reference angle and the second reference angle. Each detection sensor body 10a1, 10 for each cylinder
In this embodiment, signals of a compression stroke and an exhaust stroke after one rotation thereof are obtained from a2 and 10a3.

In the crank angle detector 10 shown in FIG. 2C, two detection sensor bodies 10 having a phase interval of 120 ° are used.
a, 10a, and the rotor 48 for detection is provided with one striker 10b having a length corresponding to a crank angle of 120 °. This is an embodiment in which signals of the compression stroke and the exhaust stroke after one rotation thereof are obtained for each cylinder using the output polarity of the crank angle sensor. The number of rotations (rotational speed) is detected from the crank angle detector.

The first embodiment will be described with reference to the example of FIG.
In the first embodiment, a cylinder discriminating method of a four-cycle three-cylinder engine will be described. As shown in FIG. 1, a crank angle signal is generated at a predetermined crank angle of each cylinder, and a signal for the cylinder determination is obtained. Specifically, for example, before the top dead center of the compression stroke of each cylinder (hereinafter referred to as B
The strikers 10b, 10b, 10b are arranged at 45 ° and BTDC 5 ° (abbreviated as TDC) so that signals having different polarities are generated. However, since it is a 4-cycle engine, the exhaust stroke B 360 ° after that
Signals are also generated at TDC 45 ° and BTDC 5 °. In addition to the signal for each cylinder, for example, the first cylinder B
Striker 10c is arranged so that a signal for cylinder discrimination is generated before TDC 45 °.

The output signal of the detection sensor body 10a is
A first reference angle signal is generated when the detection ends approach and match the strikers 10b and 10c, while a second reference angle signal having a polarity opposite to that of the first reference angle signal is generated when the detection ends move away from the match. appear. (Time) interval between the first reference angle signal and the second reference angle signal having different polarities (a: interval between the first reference angle signal and the second reference angle signal, b: second reference angle signal to the first reference angle signal) (Interval of the BTDC), it is possible to determine which cylinder the BTDC 45 ° signal and the BTDC 5 ° signal belong to. (For example, referring to FIG. 1, when the interval a is larger than the immediately preceding interval b by a predetermined value or more, the signal is transmitted to the first interval.
The BTDC signal of the cylinder is recognized as the BTDC5 ° signal of the cylinder, the signal of the subsequent polarity is recognized as the BTDC45 ° signal of the second cylinder, the signal of the same polarity thereafter is recognized as the BTDC5 ° signal of the second cylinder, and the signal of the opposite polarity is recognized as the BTDC45 signal of the third cylinder. The subsequent signals of the same polarity are sequentially recognized as the BTDC 5 ° signal of the third cylinder. )

In FIG. 2B, three sensor bodies 10a1, 10a2, and 10a3 correspond to the respective cylinders. In this structure, it is not possible to determine from which cylinder the generated signal is from. Since it is unnecessary, the load of calculation is smaller than that of the example of FIG. FIG.
In the case shown in (b), the structure can be simplified by two sensor bodies.

However, it is impossible to judge whether the generated signal is a signal of the compression stroke or a signal of the exhaust stroke only from the crank angle signal output from the crank angle detector 10. Therefore, a configuration is adopted in which a rotation signal can be detected from a camshaft that normally rotates at a ratio of 1/2 of the crankshaft, and the stroke of each cylinder is recognized. On the other hand, in the present invention, the rotation fluctuation is detected from the crank angle signal, and the stroke is determined based on the rotation fluctuation, so that the conventional cam shaft angle sensor can be eliminated.

4 and 5 show an example of a procedure for detecting rotation fluctuation according to the first embodiment.
As shown in FIG. 1, a rotation (rotational speed) fluctuation at the time of low rotation of the four-cycle three-cylinder engine is shown. In the low rotation range where the inertia force is small, rotation fluctuation occurs mainly due to an increase in the rotation of the combustion stroke for each cylinder and a decrease in the rotation of the compression stroke. In an odd-cylinder (single-cylinder, three-cylinder, five-cylinder, etc.) four-stroke engine, an odd number of combustions occurs in one cycle (two rotations), so that rotation fluctuations (rise, descent) between the same crank angles are switched every rotation. . The inventor pays attention to this point, and detects a rotation fluctuation between the same crank angles, and performs cylinder discrimination. The rotation fluctuation can be calculated easily and quickly by a computer by performing a calculation such as dividing the mounting angle of the known sensor at the time interval. In addition to the reference angle sensor, a sensor for detecting the crank rotation speed is used. There is no need to attach.

For example, BTDC 45 ° of the first cylinder and BTD
By comparing the average rotation speed between C5 ° (40 ° / time interval a) and the average rotation speed between BTDC45 ° of the second cylinder and BTDC5 ° (40 ° / time interval at that time), It is possible to determine whether the rotation has increased or decreased in the section. In this section, since the influence of the compression stroke of the second cylinder and the influence of combustion of the first cylinder appear every rotation, when the rotation speed of this section increases as shown in the flowchart, the combustion stroke of the first cylinder, If it has fallen, it can be determined that it is the compression stroke of the second cylinder. Once the determination is made, the cycle is repeated thereafter. Therefore, once the result of the determination is stored, the cylinder can be determined thereafter.

The procedure shown in the flowcharts of FIGS. 4 and 5 will be described in detail. This procedure can be executed by creating software such as a program in an appropriate OS or language and storing it in the ROM or memory of the control device. That is, the first reference angle signal is detected and the second reference angle signal immediately before is detected.
An interval b with the reference angle signal is calculated (step (hereinafter, abbreviated as S) 1), a second reference angle signal is detected, and the immediately preceding first angle signal is detected.
An interval a with the reference angle signal is calculated (step S2). The comparison between the intervals a and b is performed based on whether or not a> a + b is satisfied (S3). If not (No), the process returns to S1.

On the other hand, when it is established, the BTDC of 5 ° of the first cylinder (hereinafter abbreviated as # 1) is recognized, and the BTDC of the first cylinder is recognized.
The average rotation speed between the 45 ° signal and the BTDC 5 ° signal is calculated (# 1A) and stored (S4). Next, the reference angle signal of # 1 is detected and recognized as the BTDC 45 ° signal of # 2 (S5). The second reference angle signal is detected, and the BTDC5 of # 2 is detected.
BTDC 45 ° signal and BTDC 5 °
The average rotation speed between the signal and the signal is calculated (# 2A) and stored (S6). Then, the calculated average rotation speeds # 1A and # 2A
The rotation difference X (= # 2A- # 1A) is calculated (S7), and the rotation speed is compared based on whether the rotation difference is smaller than 0 (X <0) (S8). In this case, it can be seen that the rotation speed increases when the rotation difference is 0 or more, and decreases when the rotation difference is smaller than 0.

If the result of the determination in S8 is Yes, the rotational speed has decreased, and the process proceeds to S9 to S24.
If it is o, the number of rotations is increasing, and S2 shown in FIG.
The process proceeds to steps S5 to S40.

In the processing after S9, the first reference angle signal is detected, recognized as the BTDC 45 ° signal in the exhaust process of the third cylinder (S9), the second reference angle signal is detected, and this is detected by the third cylinder. It is recognized as a BTDC 5 ° signal in the exhaust process (S10).
Next, a first reference angle signal is detected (S11), and a second reference angle signal is detected (S12). Correspondence between the crankshaft and the first cylinder is determined by the reference angle signal. Next, a first reference angle signal is detected, and is detected by the BTDC in the compression process of the first cylinder.
The signal is recognized as a 45 ° signal (S13), a second reference angle signal is detected, and this is recognized as a BTDC 5 ° signal in the compression process of the first cylinder (S14). Then, the first reference angle signal is detected,
This is recognized as a BTDC 45 ° signal in the exhaust process of the second cylinder (S15), a second reference angle signal is detected, and recognized as a BTDC 5 ° signal in the exhaust process of the second cylinder (S1).
6). Next, the first reference angle signal is detected and recognized as a BTDC 45 ° signal in the compression process of the third cylinder (S1).
7) The second reference angle signal is detected and recognized as a BTDC 5 ° signal in the compression process of the third cylinder (S18). Then, the first reference angle signal is detected (S19), and the second reference angle signal is detected (S20). Next, a first reference angle signal is detected, which is recognized as a BTDC 45 ° signal in the exhaust process of the first cylinder (S21), a second reference angle signal is detected, and the BTDC 5 ° in the exhaust process of the first cylinder is detected. Signal (S
22). Next, the first reference angle signal is detected and is
It is recognized as a BTDC 45 ° signal in the cylinder compression process (S2
3), a second reference angle signal is detected and recognized as a BTDC 5 ° signal in the compression process of the second cylinder (S24). Then, the process returns to S9.

On the other hand, in the processing after S25 to S40, the recognition of the detected first reference angle signal and the second reference angle signal as to whether the compression step or the exhaust step is performed is the reverse of the above S9 to S24. The description is omitted.

The flowcharts shown in FIGS. 6 and 7 perform the above-described determination when the periodicity of the rotation fluctuation is temporarily disturbed due to a sudden load fluctuation or the like. It is an example of a procedure for re-determining. That is, steps S1 to S18 in FIG.
The processing is executed in the same procedure as in step S41. In steps S41 to S48, the same procedure as in step S1 to S8 is executed.
5 to S34 execute the same procedure as that of FIG.
In step 8, the same procedure as in steps S1 to S8 is executed to perform re-determination. That is, in S48 and S58, if the determination result is different from the initial determination in S8, the cylinder determines the exhaust process and the compression process in reverse.

If the accuracy of the determination is more important than the determination speed, the determination may be performed a plurality of times, and the cylinder determination may be terminated when the results of the determinations match a plurality of times. In addition, discrimination is performed in the low rotation range (including during cranking) where the rotational inertia force is small and rotation fluctuations are large, and the high rotation range with small rotation fluctuations can be continued with the discrimination pattern in the low rotation range. It is. In this case, an inexpensive arithmetic processing device having a low arithmetic speed can be configured.

The embodiment of the present invention is not limited to a three-cylinder engine, and similar effects can be obtained in other four-cycle engines having an odd number of cylinders.

Next, a second embodiment of the present invention will be described with reference to FIG.
It will be described based on. FIG. 8 shows the timing of a four-cycle three-cylinder engine. In the second embodiment, cylinder discrimination is performed when the number of reference crank angle signals is small (three signals every 120 ° per rotation). In the second embodiment, FIG.
(C) Two crank angle sensor bodies 10a, 1
Using the output polarity of 0a, the reference crank angle signal for each cylinder (# 1α: reference signal for the first cylinder, # 2α: reference signal for the second cylinder, # 3α: reference signal for the third cylinder) is 120. °
It is configured to be able to detect each time. This reference angle is arranged so as to be 120 ° before and after the compression top dead center, and the average rotation speed between 120 ° from the previous reference crank angle signal is calculated for each signal input. 1, the average rotation speed near the compression top dead center, # 2 the average rotation speed near the exhaust top dead center, # 3 the average rotation speed near the compression top dead center, # 1 the average rotation speed near the exhaust top dead center, # (2) The average rotation speed near the compression top dead center and the average rotation speed near the # 3 exhaust top dead center can be detected in this order.

I) By calculating the difference between the average rotational speeds at every 120 °, cylinder discrimination can be accurately performed even with a small crank angle signal. For example, in FIG. 8, # 1α and # 2α
Average rotation speed a between # 2α and # 3α average rotation speed b
If A = ba is positive, it can be determined that the current # 3α is a reference signal for the third cylinder compression stroke. Conversely, FIG.
, The average rotational speed d between # 1α and # 2α, and # 2α
Since the difference of the average rotational speed e between # 3 and # 3α: D = ed is negative, it can be determined that # 3α is the reference signal for the third cylinder exhaust stroke.

Ii) Also, fewer reference signals, eg, #
Even in the case of 2α and # 3α alone, the interval becomes the average rotation speed near the compression top dead center where the rotation decreases due to compression every 360 ° and the average rotation speed near the exhaust top dead center where the rotation increases due to combustion. The cylinder discrimination can be accurately performed by calculating the rotation difference for each °. For example, in FIG. 8, since eb is negative (eb <0), it can be determined that the current # 3α is a reference signal for the third cylinder exhaust stroke. Conversely, since be is positive, it can be determined that the current # 3α is a reference signal for the third cylinder compression stroke. iii) The above i), i
It is also possible to judge each of them in i) and determine that the judgment is completed when the judgment results match.

FIG. 9 shows a third embodiment of the present invention. FIG. 9 shows a configuration in which the number of reference crank angle signals is small (three signals every 120 ° for one rotation) and input at the reference position of ignition. In the third embodiment, a reference ignition crank angle signal for each cylinder (# 1α: a first cylinder reference signal, # 2α: a second cylinder reference signal, # 2) is utilized by utilizing output polarities of two crank angle sensors. 3α: reference signal for the third cylinder) is detected every 120 °.

The difference between the average rotation speeds for each 120 ° is calculated, and the rotation differences A, B, C, D, E, and F for the average rotation speeds are calculated.
Is calculated. The rotation differences A, C, and E in the combustion stroke of each cylinder reflect the state of combustion, and become positive if the combustion is good. Conversely, B,
D and F mainly reflect the compression stroke and do not become positive.
Accordingly, cylinder detection is possible by detecting a section where the rotation difference is positive. Further, as in the third embodiment, the determination can be made with high accuracy by performing the determination a plurality of times even in the case where the determination is made in the section where the condition is bad, and determining that the determination is completed when the determination results match.

The following conditions can be added to the cylinder discrimination in the first to third embodiments. In an internal combustion engine, acceleration and deceleration may differ from steady-state rotational fluctuations. Acceleration and deceleration are detected from changes in throttle opening, changes in boost (intake negative pressure), and rotational fluctuations above a set value. By making a configuration in which the determination is not performed during acceleration or deceleration exceeding the set value, erroneous determination can be prevented, and the determination accuracy can be improved. Further, the ignition and the injection cut are not executed because they are different from the periodic rotation fluctuation at the steady state. Thereby, erroneous determination can be prevented, and the determination accuracy can be improved.

Further, from the cylinder discrimination result of the embodiment, it is possible to prevent wasteful ignition cut (ignition cut at exhaust top dead center: waste of ignition energy due to ignition unrelated to combustion, an ignition control circuit by unnecessary ignition, and It can prevent heat and temperature rise of the ignition coil, reduce power consumption,
Reliability is improved. In particular, it is effective in a high rotation range where the ignition cycle is short. In the present invention, the determination is made in the low rotation range, and then the waste fire cut control can be executed. ), Cylinder-specific timing injection angle control, cylinder-specific ignition timing control, cylinder-specific injection amount control, etc., firstly, wasteful fire is cut for only one cylinder, and subsequent rotation fluctuations are detected to detect abnormalities (misfire, etc.). Only when there is no extreme decrease in rotation), the waste fire cut control for the remaining cylinders and the above-described cylinder-specific control are performed. This allows the engine to stall (engine stall) even if, for example, an incorrect determination is made.
Can be prevented, and the determination can be performed again.

[0037]

As described above, according to the present invention, in a four-cycle internal combustion engine having an odd number of cylinders, the process of each cylinder is determined based on the crank angle signal and the rotation fluctuation. Since cylinder discrimination (cylinder process discrimination) can be performed only by means, a sensor for a camshaft can be eliminated, and accuracy is high in a system in which cylinder discrimination is performed only by a camshaft. In addition, it is possible to improve the poor accuracy due to the operating state and the slack of the belt when only the camshaft is used. Further, in the present invention, by detecting rotation fluctuations in a crank angle region where rotation fluctuations appear remarkably, and performing cylinder discrimination based on the detected fluctuation amount, the top dead center (compression top dead center) adjacent to each cylinder is determined. Point, exhaust top dead center), the rotational fluctuation can be detected by comparing the rotational speed before and after.

Further, according to the present invention, by detecting the average number of revolutions before and after the top dead center, in the case of an internal combustion engine having an odd number of cylinders, it is possible to detect a section between a peak and a valley every revolution. The rotation fluctuation can be detected by comparing these average rotation speeds. For example, by comparing the average rotation speed before one rotation, the stroke can be accurately determined. In addition, it is sufficient to calculate only the average number of rotations between the same angles for each rotation, so that it is possible to determine even a small reference angle signal and the calculation is easy. Further, it is possible to determine even with a small reference angle signal. Also,
In the present invention, cylinder discrimination is performed a plurality of times, and when the discrimination results match, discrimination is completed, thereby preventing temporary load fluctuation and erroneous discrimination during acceleration / deceleration, thereby improving accuracy. Further, in the present invention, the accuracy is improved by performing various cylinder discrimination logics and completing the discrimination when both discrimination results match.

Further, in the present invention, the cylinder discrimination is performed in a predetermined low rotation speed range of the internal combustion engine, while the determination result in the low rotation speed range can be used in the high rotation speed range.
Rotational fluctuations are easy to discern and accuracy is high. Since the calculation does not need to be performed in a high rotation range where the rotation cycle is fast, it is possible to configure an inexpensive processing device having a low calculation speed. The cylinder discrimination can be performed also during cranking. Further, in the present invention, cylinder discrimination can be performed at a predetermined throttle opening and a predetermined boost pressure. For example, acceleration and deceleration may be different from the steady-state rotation fluctuation.
It is also possible not to execute. In the present invention,
Cylinder discrimination can be made not to be performed during ignition or injection cut, and thus, during ignition or injection cut, it is not executed because it differs from steady-state rotation fluctuation. The accuracy is improved. Further, in the present invention, based on the cylinder discrimination signal, the useless fire cut is performed for one cylinder, and when the rotation fluctuation does not occur as a result of the useless fire cut, the useless fire cut control or the like for other cylinders is performed. Cylinder-by-cylinder control can be performed. If there is no abnormality in the check, the unnecessary fire cut of the other cylinder and the other cylinder-specific control are performed. Thereby, for example, even in the event of an erroneous determination, engine stall can be prevented, and the determination can be performed again.

[Brief description of the drawings]

FIG. 1 is a timing chart showing the timing of a four-cycle three-cylinder engine according to Embodiment 1 of the present invention, and an explanatory diagram of a configuration example of a crank angle detector.

FIGS. 2A to 8C are explanatory diagrams of an engine speed change state, a configuration example of a crank angle detector, and an output timing chart according to the first embodiment.

FIG. 3 is a block diagram of a control device for an internal combustion engine embodying the present invention.

FIG. 4 is a flowchart illustrating a procedure of cylinder determination according to the first embodiment.

FIG. 5 is a flowchart following FIG. 4;

FIG. 6 is a flowchart illustrating another procedure of cylinder discrimination according to the first embodiment.

FIG. 7 is a flowchart following FIG. 6;

FIG. 8 is a timing chart showing the timing of an engine speed, a reference angle signal, and the like of a four-cycle three-cylinder engine according to Embodiment 2 of the present invention, and a configuration example explanatory diagram of a crank angle detector.

FIG. 9 is a timing chart illustrating timings of an engine speed, a reference angle signal, and the like of a four-cycle three-cylinder engine according to a third embodiment, and a configuration example explanatory diagram of a crank angle detector.

[Explanation of symbols]

 10 Crank angle detector 10a Sensor body 10b striker

Claims (9)

[Claims] 1. A four-stroke internal combustion engine having an odd number of cylinders, means for generating a predetermined crank angle signal corresponding to each cylinder for each rotation of a crankshaft of the internal combustion engine, and detecting rotation fluctuation of the crankshaft. A cylinder discriminating device for discriminating a process of each cylinder based on the crank angle signal and rotation fluctuation. 2. The cylinder discriminating apparatus for an internal combustion engine according to claim 1, wherein a rotation fluctuation in a crank angle region where the rotation fluctuation appears remarkably is detected, and a cylinder discrimination is performed based on the detected fluctuation amount. 3. The cylinder discrimination is performed by comparing an average rotation speed in a crank angle region where the rotation fluctuation has a mountain shape with an average rotation speed in the same angle region one rotation before. A cylinder discriminating apparatus for an internal combustion engine according to the above. 4. A cylinder discriminating apparatus for an internal combustion engine according to claim 2, further comprising means for discriminating the cylinder a plurality of times and completing the discrimination when the discrimination results match. 5. The internal combustion engine according to claim 1, wherein both the cylinder discrimination described in claim 2 and the cylinder discrimination described in claim 3 are performed, and the discrimination is completed when both discrimination results match. Cylinder discriminator. 6. The engine according to claim 1, wherein the cylinder discrimination is performed in a predetermined low rotation speed range of the internal combustion engine, and the determination result in the low rotation speed range is used in a high rotation speed range. 2. The cylinder discriminating apparatus for an internal combustion engine according to claim 1. 7. The cylinder discriminating apparatus for an internal combustion engine according to claim 1, wherein cylinder discrimination is performed at a predetermined throttle opening and a predetermined boost pressure. 8. The cylinder discriminating apparatus for an internal combustion engine according to claim 1, wherein cylinder discrimination is not performed during ignition or injection cut. 9. Based on the discrimination signal of the cylinder, waste ignition cut of one cylinder is performed, and when the rotation fluctuation does not occur as a result of the waste fire cut, waste fire cut control and other cylinders of other cylinders are performed. The cylinder discriminating device for an internal combustion engine according to any one of claims 1 to 8, wherein a separate control is performed.