JPH10339204A - Cylinder discriminating device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a deterioration of an exhaust gas emission at the time of discriminating a cylinder based on burning conditions eliminating a sensor at a cam-shaft side for a cost reduction. SOLUTION: A fuel is injected simultaneously into a first cylinder and a fourth cylinder during the period from the time when the intake valve of a cylinder (first cylinder) on the way of an intake stroke is closed at a first detection time of lacked teeth to the time when the intake valve of a cylinder (fourth cylinder) on the way of an expansion stroke is opened at the first detection time of lacked teeth, namely the period when one (first cylinder) is on the way of a compression stroke and the other (fourth cylinder) is on the way of an exhaust stroke. Afterwards, fuel injections into the first cylinder and the fourth cylinder are similarly performed after the detections of lacked teeth at odd-numbered times. Also, ignitions to the first cylinder and the fourth cylinder are carried out simultaneously during the period when the both cylinders are at near their top dead centers. An occurrence of combustion is detected by an ionic current after the ignition. When the ionic current is detected, it becomes clear that the cylinder is at the compressive top dead center.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cylinder discriminating apparatus for an internal combustion engine.

[0002]

2. Description of the Related Art In a four-stroke (stroke) cycle reciprocating engine, an intake stroke,
A compression stroke, an expansion stroke (also called a combustion stroke, an explosion stroke, etc.) and an exhaust stroke are performed, and one cycle is completed. Therefore, the crankshaft, which converts the reciprocating motion of the piston together with the connecting rod into rotary motion, makes two revolutions per engine cycle. In addition, since the intake and exhaust valves need to be opened and closed once per engine cycle, the camshaft that rotates in synchronization with the crankshaft to drive the intake and exhaust valves has a rotation speed that is half the rotational speed of the crankshaft. It rotates at the rotation speed. That is, the camshaft rotates once per engine cycle.

In an electronically controlled engine for controlling fuel injection timing and ignition timing, one engine cycle (720 °)
Need to detect the position inside. Therefore, it is necessary to provide a crank angle sensor on the crankshaft side or the camshaft side, but providing it on the crankshaft side provides better detection accuracy. However, when a crank angle sensor is provided on the crankshaft side, only a crank angle position in a 360 ° cycle can be detected. Therefore, it is necessary to provide a cylinder discrimination sensor also on the camshaft side. That is, in the case of a four-cylinder engine, four strokes in each cylinder are one stroke.
Shift by 80 °, 360 ° between # 1 cylinder and # 4 cylinder
Even if top dead center of # 1 cylinder and # 4 cylinder is detected by the crank angle sensor provided on the crankshaft side, one is at compression top dead center and the other is at exhaust top dead center. It cannot be determined which is at the compression top dead center. As described above, conventionally, it is necessary to provide a sensor on the camshaft side for cylinder discrimination.

By the way, at the time of starting, it is determined whether at least one of the cylinders is in the piston reciprocating cycle on the intake stroke and the compression stroke side or in the piston reciprocating cycle on the expansion stroke and the exhaust stroke side. Then, after that, the crank angle position of each cylinder can be detected only by the rotation phase of the crankshaft. Therefore, a proposal has been made to reduce the cost by omitting a sensor on the camshaft side. For example, JP-A-3-13
No. 4247 discloses that a cylinder group in a compression stroke or an exhaust stroke is determined by a sensor that detects rotation of a crankshaft,
A method of simultaneously igniting each cylinder of the cylinder group and discriminating a cylinder in which a ionic current has flowed in the cylinder, that is, a cylinder in which combustion has been confirmed, as a cylinder in a compression stroke is disclosed. doing.

[0005]

When the cylinder is determined by confirming the combustion state based on the ion current as in the prior art, a fuel-air mixture is created by injecting fuel before ignition. Need to be kept. If the injection is performed during a period in which the intake valve is open, such as during the intake stroke, misfiring is likely to occur because of the poor atomization state of the fuel. Hydrogen) is emitted, which results in deterioration of exhaust emission.

In view of such circumstances, an object of the present invention is to discriminate a cylinder based on a combustion state, thereby eliminating a sensor on a camshaft side to reduce costs, and at the same time, deteriorate exhaust emissions. It is an object of the present invention to provide a cylinder discriminating device for an internal combustion engine that does not have any problem.

[0007]

In order to achieve the above object,
According to the first aspect of the present invention, in a multi-cylinder four-stroke cycle internal combustion engine, at least one of the cylinders is provided with at least one of the cylinders so that the crank angle position of each cylinder can be detected only by the rotational phase of the crankshaft. A cylinder discriminating device for discriminating between a piston reciprocating cycle on an intake stroke and a compression stroke side or a piston reciprocating cycle on an expansion stroke and an exhaust stroke side, comprising: a rotation reference position of a crankshaft; Rotation detection means for detecting a displacement of a predetermined angle unit; and at least one cylinder having an intake valve in a closed state is identified based on an output signal of the rotation detection means, and fuel is supplied to the identified cylinder during the closed state. Detecting when the piston in the identified cylinder comes near the top dead center based on an output signal of the rotation detection means. Ignition control means for activating an ignition plug provided in the identified cylinder at the time; combustion state detection means for detecting a combustion state in the identified cylinder after activation of the ignition plug; A top dead center determining means for determining whether or not ignition of the identified cylinder has been performed in the vicinity of compression top dead center based on the combustion state detected by the state detecting means. An apparatus is provided.

[0008] According to a second aspect of the present invention, in the cylinder discriminating apparatus according to the first aspect, the fuel supply control means controls the intake air at a time when a rotation reference position is detected by the rotation detection means. At least one cylinder in a stroke or an expansion stroke is identified, and fuel is supplied to the identified cylinder when the identified cylinder is in a compression stroke or an exhaust stroke.

According to a third aspect of the present invention, in the cylinder discriminating apparatus according to the first or second aspect, the fuel supply control means detects a rotation reference position by the rotation detection means. Identify the two cylinders in a relationship where one is in the intake stroke and the other is in the expansion stroke at the time,
When the one cylinder is in a compression stroke and the other cylinder is in an exhaust stroke, fuel is simultaneously supplied to the two cylinders, and the ignition control means determines that the one cylinder has a compression top dead center. The ignition plugs of the two cylinders are simultaneously activated when the other cylinder is in the vicinity and the other cylinder is near the exhaust top dead center.

According to a fourth aspect of the present invention, in the cylinder discriminating apparatus according to the first, second, or third aspect, when the combustion state detecting means does not detect the combustion of fuel, The processing by the fuel supply control unit, the ignition control unit, the combustion state detection unit, and the top dead center determination unit is executed again.

In the cylinder discriminating apparatus for an internal combustion engine according to the first aspect of the present invention, the fuel is supplied during the opening period of the intake valve in which atomization and vaporization of the fuel are deteriorated. The fuel is always supplied only during the intake valve closing period when the atomization and vaporization of the fuel is good,
After the misfire due to the deterioration of the vaporization is suppressed, the cylinder discrimination based on the combustion state is performed.

Further, in the cylinder discriminating apparatus according to the second aspect of the present invention, fuel is injected into the cylinder in which the intake valve is closed at the earliest time after the rotation reference position of the crankshaft is detected. Therefore, the cylinder discrimination is performed early.

Further, in the cylinder discriminating apparatus according to the third aspect of the present invention, fuel is simultaneously supplied to two cylinders, one of which is in a compression stroke and the other is in an exhaust stroke, and ignition is performed at the same time. Since the determination is performed, the accuracy of the determination is improved.

Further, in the cylinder discriminating apparatus according to the fourth aspect of the present invention, when no combustion state is detected,
Since fuel supply, ignition, combustion state detection, and top dead center determination are performed again, erroneous determination of cylinder determination due to misfire is prevented.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine provided with a cylinder discriminating apparatus according to an embodiment of the present invention.
The engine 1 is an in-line four-cylinder four-stroke cycle reciprocating gasoline engine mounted on a vehicle. Engine 1
A cylinder block 2 and a cylinder head 3 are provided. A cylinder 4 extending in a vertical direction is provided in the cylinder block 2.
Are arranged side by side in the thickness direction of the paper surface, and a piston 5 is accommodated in each cylinder 4 so as to be able to reciprocate. Each piston 5
Are connected to a common crankshaft 7 via a connecting rod 6. The reciprocating motion of each piston 5 is
The rotational motion of the crankshaft 7 is converted through the connecting rod 6.

A combustion chamber 8 is provided between the cylinder block 2 and the cylinder head 3 above each piston 5. The cylinder head 3 is provided with an intake port 9 and an exhaust port 10 for communicating both outer surfaces thereof with the respective combustion chambers 8. In order to open and close these ports 9 and 10, an intake valve 11 and an exhaust valve 12 are supported on the cylinder head 3 so as to be able to reciprocate substantially vertically. In the cylinder head 3, each valve 1
Above 1 and 12, an intake camshaft 13 and an exhaust camshaft 14 are rotatably provided, respectively. Cams 15 and 16 for driving the intake valve 11 and the exhaust valve 12 are attached to the camshafts 13 and 14. Timing pulleys 17 and 18 provided at ends of the camshafts 13 and 14 respectively correspond to timing pulleys 19 and 18 provided at ends of the crankshaft 7.
Are connected by a timing belt 20.

That is, when the timing pulley 19 rotates with the rotation of the crankshaft 7, the rotation is transmitted via the timing belt 20 to the timing pulleys 17 and 1.
8 is transmitted. At this time, the rotation of the timing pulley 19 is transmitted to the timing pulleys 17 and 18 with its rotation speed reduced to half. When the intake side camshaft 13 rotates with the rotation of the timing pulley 17,
The intake valve 11 is reciprocated by the action of the cam 15, and the intake port 9 is opened and closed. When the exhaust side camshaft 14 rotates with the rotation of the timing pulley 18, the cam 16
The exhaust valve 12 reciprocates and the exhaust port 10 is opened and closed. Thus, the camshafts 13 and 14 are rotationally driven by the crankshaft 7, and the intake valve 11 and the exhaust valve 12 are opened and closed at a constant crank angle of a 720 ° cycle.

An intake passage 30 is connected to the intake port 9. An injector 32 that injects fuel toward each intake port 9 is attached to the intake passage 30.
A mixture of fuel injected from the injector 32 and air flowing in the intake passage 30 is introduced into the combustion chamber 8 via the intake valve 11 in an intake stroke, and is compressed by the piston 5 in a compression stroke.

To ignite this mixture, an ignition plug 34 is attached to the cylinder head 3. At the time of ignition, energization and interruption of the primary current of the ignition coil in the ignition device 50 are controlled by the ignition signal, and the secondary current is supplied to the ignition plug 34. Then, the air-fuel mixture introduced into the combustion chamber 8 is burned by ignition by the spark plug 34 (expansion stroke). The piston 5 reciprocates by the high-temperature and high-pressure combustion gas generated at this time, the crankshaft 7 is rotated, and the driving force of the engine 1 is obtained. The burned air-fuel mixture is guided to the exhaust port 10 via the exhaust valve 12 as exhaust gas in the exhaust stroke. An exhaust passage 36 is connected to the exhaust port 10.

A rotor 38 that rotates in synchronization with the rotation of the crankshaft 7 is attached to the crankshaft 7.
A crank angle sensor 40 that generates a pulse for each A (crank angle) is provided. The rotor 38 is
It has a missing tooth part and the time when the missing tooth is detected is
It is set to coincide with the time when a certain period has elapsed since the pistons of the # 1 cylinder and # 4 cylinder passed the top dead center.

Engine electronic control unit (engine ECU)
Reference numeral 42 denotes a microcomputer system that executes fuel injection control, ignition timing control, and the like. Further, in the present invention, the engine ECU 42 executes a cylinder discriminating process based on the combustion state. In order to detect the combustion state, an ionic current detection device 60 is provided for each cylinder in association with the ignition device 50.

FIG. 2 is a diagram showing a circuit configuration of the ignition device 50 and the ion current detection device 60. One end of a primary winding 52a of the ignition coil 52 is connected to a positive electrode of the battery 44, and the other end is connected to a collector of a transistor 54 as switching means. The emitter of the transistor 54 is grounded, and the ignition signal is applied to its base. One end of the secondary winding 52b of the ignition coil 52 is connected to the center electrode 34a of the ignition plug 34.
It is connected to the. The outer electrode 34b of the ignition plug 34 is grounded.

At the other end of the secondary winding 52b of the ignition coil 52, an ion current detector 60 is provided.
First, a capacitor 61 serving as an ion current generating power supply is connected to the secondary winding 52b. The capacitor 61 is connected in parallel with a constant voltage diode (Zener diode) 62 for limiting the voltage charged to the capacitor 61 by the secondary current of the ignition coil to a constant value.
The other end of the capacitor 61 is grounded via a diode 63 that allows current to flow only in the ground direction, and is grounded via an ion current detection resistor 64. The connection point between the capacitor 61 and the ion current detection resistor 64 is connected to the inverting amplifier circuit 66. The output of the inverting amplifier circuit 66 is guided to the engine ECU 42.

Next, the operation of the ion current detecting device 60 will be described. First, when the ignition signal goes high and the transistor 54 turns on, a current flows through the ignition coil primary winding 52a. Next, when the ignition signal is turned low and the transistor 54 is turned off to cut off the primary current, a high voltage is induced in the secondary winding 52b of the ignition coil 52, and as a result, the ignition plug 34 Spark discharge occurs. That is, when a high voltage of negative polarity is applied to the center electrode 34a of the ignition plug 34, a spark discharge occurs between the center electrode 34a and the outer electrode (ground electrode) 34b, and as shown in FIG. From the ignition coil secondary winding 52b,
Through the capacitor 61, the constant voltage diode 62, the diode 63, and the spark plug 34, a current circulates to the secondary winding 52b. In this process, the capacitor 61 sets the Zener voltage (100
(Approximately V).

When the air-fuel mixture in the combustion chamber is ignited and burned by the spark discharge at the ignition plug 34, the air-fuel mixture is ionized. When the mixture is in an ionized state, the electrode between the electrodes of the ignition plug 34 has conductivity. In addition, since a voltage is applied between both electrodes of the ignition plug 34 by the charging voltage of the capacitor 61, an ionic current flows. That is, as shown in FIG. 4, the ion current flows from one end of the capacitor 61 to the other end of the capacitor 61 via the ignition coil secondary winding 52b, the spark plug 34, and the ion current detection resistor 64. Flows. Then, a potential of “−ion current value × detection resistance value” appears at a connection point between the ion current detection resistor 64 and the capacitor 61, and the potential is inverted and amplified by the inverting amplifier circuit 66. Finally, the output of the inverting amplifier circuit 66 is supplied to the ECU 42 as an ion current signal. Based on the ion current signal, the ECU 20
Can determine whether or not combustion has occurred.

FIG. 5 is a diagram showing a configuration of a device relating to starting of the engine. This engine is a four-cylinder engine. The # 1 cylinder and the # 4 cylinder have the same piston position, the # 3 cylinder and the # 2 cylinder have the same piston position, and their piston positions are different. Is 180 ° CA. When the engine is started, the power of the starter motor 45 is transmitted to the crankshaft 7 via the starter pinion 46 and the ring gear 47, so that the crankshaft 7 is rotated. Then, as described above, the rotor 38 and the crank angle sensor 40 can detect the rotational reference position of the crankshaft 7 and the rotational displacement in units of 10 ° from the reference position. The rotation reference position detected by the missing tooth is # 1 cylinder and # 4
This is one of the periods in which one of the cylinders is in the intake stroke and the other is in the expansion stroke. However, it cannot be determined which cylinder is in the intake stroke. Therefore, the engine ECU 42 drives the starter motor 45 at the time of starting and, as described below, uses the ion current detecting device 60 provided for each cylinder in association with the ignition device 50 to perform the cylinder discriminating process. Execute

FIG. 6 is a time chart for explaining the cylinder discriminating process according to the first embodiment. After the engine is started, the first tooth is missing in the intake stroke of the # 1 cylinder (reference position of rotation of the crankshaft). Is detected. The first missing tooth from the time when the intake valve of the cylinder in the intake stroke (# 1 cylinder in FIG. 6, which is unknown) is closed at the first missing tooth detection timing. The period until the intake valve of the cylinder (in FIG. 6, # 4 cylinder, which is unknown) in the expansion stroke at the detection timing is opened, that is, one of the cylinders (in this case, # 1 cylinder) is opened. On the other hand (in this case, $ 4
In the period in which the cylinder) is in the exhaust stroke, to ♯1 cylinder and ♯4 cylinder, as shown in FI ₁ and FI ₃ in the figure, simultaneously inject fuel.

Thereafter, the fuel injection to the # 1 cylinder and the # 4 cylinder is similarly executed after the odd-numbered missing tooth detection. Further, ignition is simultaneously performed on the # 1 cylinder and the # 4 cylinder when both cylinders are near the top dead center. After ignition, whether or not combustion has occurred is determined by the ionic current. Such injection, ignition, and when running the combustion detection, as shown in FIG. 6, in the ♯4 cylinder, the fuel FI ₃ is sucked into the cylinder at the intake stroke IS _3, by the ignition IG ₃ are burned, the ion current is detected, # 4 cylinder during ignition IG ₃ run to find that there was a compression top dead center. Similarly, in ♯1 cylinder, fuel FI ₁ is sucked into the cylinder at the intake stroke IS _1, it is burned by the ignition IG ₁ for the ion current is detected, the ignition IG ₁ run ♯1 It turns out that the cylinder was at compression top dead center.

[0030] In other words, the earliest case, cylinder discrimination is completed at the time of ignition IG ₃ execution. When a misfire when the ignition IG ₃ execution occurs, the cylinder discrimination at the time of ignition IG ₁ run completed. Similarly, fuel injection FI ₂ in # 1 cylinder,
Process of suction IS ₂ and ignition IG _2, and the fuel injection FI ₄ in ♯4 cylinders, even in the course of inhalation IS ₄ and the ignition IG _4, it is possible cylinder discrimination.

FIG. 7 is a time chart for explaining the cylinder discriminating process according to the first embodiment, showing a case where a missing tooth is detected for the first time in the intake stroke of # 4 cylinder after the engine is started. It is. In the case of FIG. 7, as compared with the case of FIG. 6, the relationship between the # 1 cylinder and the # 4 cylinder is simply reversed, and it is easily understood that the cylinder discrimination processing is performed similarly. Will be. Also, in the above description,
Although the cylinder discriminating process is performed between the # 1 cylinder and the # 4 cylinder, the cylinder discriminating process may be performed between the # 2 cylinder and the # 3 cylinder. And according to the above method,
Since fuel is injected only during the intake valve closing period, all of the fuel is supplied to the cylinder without waste and burned, so that unburned fuel is not discharged.

FIG. 8 is a flowchart showing a control procedure executed by the ECU to realize the above-described cylinder discriminating process according to the first embodiment. First, step 10
In step 1, the control waits until a missing tooth, that is, a reference position is detected by the crank angle sensor 40. When a missing tooth is detected, in step 102, the counter for calculating the crank angle based on the output signal of the crank angle sensor 40 is reset and started. Next, in step 103, it is determined whether or not the odd number of missing teeth is detected. If the number is odd, the process proceeds to step 104. On the other hand, if the number is even, the simultaneous injection to the # 1 cylinder and # 4 cylinder is executed. Steps 104 and 10
The process skips Step 5 and proceeds to Step 106.

In step 104, the crank angle is calculated as shown in FIG.
And waits in a self-loop until the simultaneous injection timing for the # 1 cylinder and # 4 cylinder is reached, as shown in FIG. Then, when the injection timing has been reached, in step 105, simultaneous injection is executed for the # 1 cylinder and the # 4 cylinder. Next, in step 106, the crank angle is set to {cylinder # 1 and # 2} as shown in FIGS.
It waits in a self-loop until it reaches the simultaneous ignition timing for the four cylinders. And when the ignition timing is reached,
In step 107, simultaneous ignition is performed for the # 1 cylinder and the # 4 cylinder.

After ignition, at step 108
In order to determine whether combustion has occurred in one cylinder and # 4 cylinder, the ionic current in each cylinder is detected. Next, in step 109, it is determined whether or not ions are generated in the # 1 cylinder based on the ion current detection value of the # 1 cylinder. When the generation of ions in the # 1 cylinder is recognized, the routine proceeds to step 111, where it is determined that the # 1 cylinder is at the compression top dead center. On the other hand, when the generation of ions in the # 1 cylinder is not recognized, it is determined in step 110 whether or not ions are generated in the # 4 cylinder based on the ion current detection value of the # 4 cylinder. Then, when the generation of ions in the four-cylinder is recognized, the routine proceeds to step 112, where
It is determined that the four cylinders were at the compression top dead center. On the other hand, if ion generation in the # 4 cylinder is not recognized, step 1
Return to 01.

As shown in FIG. 6, after starting the engine,
If a missing tooth is detected for the first time in the intake stroke of the # 1 cylinder, the compression top dead center of the # 4 cylinder is detected in the second running of this routine. On the other hand, as shown in FIG. 7, when the missing tooth is detected for the first time in the intake stroke of the # 4 cylinder after the engine is started, in the second running of this routine,
# 1 The compression top dead center of one cylinder is detected. In any case, when a misfire occurs, the compression top dead center of either the # 1 cylinder or the # 4 cylinder is always detected in the third and subsequent runs of this routine.

FIGS. 9 and 10 are time charts for explaining the cylinder discriminating process according to the second embodiment.
FIG. 9 shows a case where a missing tooth is detected for the first time in the intake stroke of # 1 cylinder after the engine is started, and FIG. 10 shows a case where a missing tooth is detected for the first time in the intake stroke of # 4 cylinder after the engine is started. Show the case. In the first embodiment, the simultaneous injection is executed for the # 1 cylinder and the # 4 cylinder,
Although the cylinder discrimination was performed, in the second embodiment, as shown in those figures, at the time of detecting the missing tooth of the odd number of times,
Fuel injection is performed only on # 1 cylinder, and fuel injection is performed only on # 4 cylinder upon detection of even-numbered missing teeth.
However, ignition is performed simultaneously for both cylinders, as in the first embodiment.

In the case of FIG. 9, in the # 1 cylinder, the fuel FI
₁But the intake stroke IS₁At the ignition IG
₁Ignited by detecting the ionic current
IG₁During execution, the # 1 cylinder was at compression top dead center.
It turns out that. Even ignition IG₁Does not cause combustion
す な わ ち 4 cylinders even if a misfire occurs
In the fuel FI_TwoBut the intake stroke IS_TwoIn the cylinder at
Inhaled, ignition IG_TwoBurned at
By detecting the flow, the ignition IG_TwoAt runtime
It turns out that # 4 cylinder was at compression top dead center. This
As shown in FIG. 9, the earliest case is the third missing tooth detection.
The cylinder discrimination is completed in a later cycle. On the other hand, in the case of FIG.
In this case, the fuel FI shown in FIG.₁But,
Intake stroke IS ₁At the ignition IG₁At
If the cylinder discrimination is completed as soon as
In this case, there are two cycles. In addition,
Reversing the firing order, # 4 cylinder at the time of odd missing tooth detection
Fuel injection to the
Of course, you can inject fuel into one cylinder
No.

FIGS. 11 and 12 are flowcharts showing a control procedure executed by the ECU to realize the above-described cylinder discriminating process according to the second embodiment. First,
In step 201, the flag X is reset to 0. Next, at step 202, the process stands by until the missing tooth, that is, the reference position is detected by the crank angle sensor 40. When a missing tooth is detected, in step 203, the counter for calculating the crank angle based on the output signal of the crank angle sensor 40 is reset and started. In step 204, the crank angle is adjusted as shown in FIGS.
It waits in a self-loop until it reaches the injection timing for # 1 cylinder or # 4 cylinder as indicated by 0. When the injection timing has been reached, at step 205, the flag X
And if X = 0, step 21
The process proceeds to step 221 when X = 1.

In step 211, the flag X is set to "1". Then, in step 212, injection is performed for the # 1 cylinder. Next, at step 213, the process waits in a self-loop until the crank angle reaches the simultaneous ignition timing for the # 1 cylinder and the # 4 cylinder as shown in FIGS. When the ignition timing has been reached, in step 214, simultaneous ignition is performed on the # 1 cylinder and the # 4 cylinder. After the ignition, in step 215, the ionic current in the # 1 cylinder is detected in order to determine whether or not combustion has occurred in the # 1 cylinder. Next, at step 216, it is determined whether or not ions are generated in the # 1 cylinder based on the ion current detection value. When generation of ions is recognized, step 21
The routine proceeds to 7, where it is determined that the # 1 cylinder is at the compression top dead center, and this routine ends. On the other hand, when generation of ions is not recognized, the process returns to step 202.

Steps 221 to 227 executed when it is determined in step 205 that X = 1 execute the same processing as steps 211 to 217 described above for the # 4 cylinder. Thus, according to the present routine, the top dead center determination processing is alternately performed on the # 1 cylinder or # 4 cylinder for each run, and the cylinder determination processing of FIGS. 9 and 10 is realized.

After the completion of the cylinder discriminating process, the injection timing and the ignition timing are set for each cylinder. That is, at the time of starting, if the fuel is injected only while the intake valve is closed, the influence of the injection timing on the combustion is small. However, during normal operation, it is desirable to set an optimal injection timing for each cylinder in order to maximize engine efficiency, and the injection timing is controlled for each cylinder after the cylinder discrimination is completed. Also, regarding simultaneous ignition, if simultaneous ignition is performed at all times, useless sparks will be generated, causing a problem that the electrode of the spark plug will be consumed earlier.Therefore, after the cylinder discrimination is completed, the ignition timing is executed for each cylinder. You.

[0042]

As described above, according to the present invention,
A cylinder discriminating device for an internal combustion engine is provided which eliminates a sensor on a camshaft side by performing cylinder discrimination based on a combustion state to reduce costs and does not cause deterioration of exhaust emission. .

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine including a cylinder discriminating apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a circuit configuration of an ignition device and an ion current detection device.

FIG. 3 is a diagram for explaining a flow of a discharge current when a spark discharge occurs in an ignition plug.

FIG. 4 is a diagram for explaining the flow of ion current after spark discharge.

FIG. 5 is a diagram showing a configuration of a device related to starting of an engine.

FIG. 6 is a time chart for explaining a cylinder discrimination process according to the first embodiment, showing a case where a missing tooth is detected for the first time in an intake stroke of # 1 cylinder after the engine is started.

FIG. 7 is a time chart for explaining a cylinder discrimination process according to the first embodiment, showing a case where a missing tooth is detected for the first time in an intake stroke of # 4 cylinder after the engine is started.

FIG. 8 is a flowchart illustrating a control procedure executed by an ECU to realize a cylinder determination process according to the first embodiment.

FIG. 9 is a time chart for explaining a cylinder discrimination process according to the second embodiment, showing a case where a missing tooth is detected for the first time in an intake stroke of # 1 cylinder after the engine is started.

FIG. 10 is a time chart for explaining a cylinder discriminating process according to the second embodiment, in which # 4 is set after the engine is started;
This shows a case where a missing tooth is detected for the first time in the intake stroke of a cylinder.

FIG. 11 is a flowchart (1/2) showing a control procedure executed by an ECU to realize a cylinder determination process according to the second embodiment.

FIG. 12 is a flowchart (2/2) showing a control procedure executed by the ECU to realize the cylinder determination processing according to the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... In-line 4 cylinder 4-stroke cycle reciprocating gasoline engine 2 ... Cylinder block 3 ... Cylinder head 4 ... Cylinder 5 ... Piston 6 ... Connecting rod 7 ... Crank shaft 8 ... Combustion chamber 9 ... Intake port 10 ... Exhaust port 11 ... Intake valve 12 ... Exhaust valve 13 ... Intake side camshaft 14 ... Exhaust side camshaft 15 ... Intake side cam 16 ... Exhaust side cam 17,18,19 ... Timing pulley 20 ... Timing belt 30 ... Intake passage 32 ... Injector 34 ... Ignition plug 34a ... Center electrode 34b Outside electrode 36 Exhaust passage 38 Rotor 40 Crank angle sensor 42 Engine electronic control unit (engine ECU) 44 Battery 45 Starter motor 46 Starter pinion 47 Ring gear 50 Ignition device 52 Ignition coil 52a ... primary winding 52 b ... Secondary winding 54 ... Transistor 60 ... Ion current detection device 61 ... Capacitor 62 ... Constant voltage diode (Zener diode) 63 ... Diode 64 ... Ion current detection resistor 66 ... Inverting amplifier circuit

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI F02P 17/00 F02P 17/00 U

Claims (4)

[Claims] In a multi-cylinder four-stroke cycle internal combustion engine, at least one of a crank angle position of each cylinder can be detected only by a rotation phase of a crankshaft.
A cylinder discriminating device for discriminating, for one of the cylinders, whether the cylinder is in a piston reciprocating cycle on an intake stroke and a compression stroke side or in a piston reciprocating cycle on an expansion stroke and an exhaust stroke side. Rotation detection means for detecting a displacement of a predetermined angle unit from the rotation reference position; and at least one cylinder in which an intake valve is in a closed state based on an output signal of the rotation detection means. Fuel supply control means for supplying fuel to the identified cylinder; detecting when the piston in the identified cylinder comes near the top dead center based on the output signal of the rotation detection means. Ignition control means for operating an ignition plug provided in the identified cylinder; combustion state detection means for detecting a combustion state in the identified cylinder after operation of the ignition plug; A top dead center determining means for determining whether or not ignition of the identified cylinder is performed in the vicinity of the compression top dead center based on the combustion state detected by the combustion state detecting means. Cylinder discriminator. 2. The fuel supply control means identifies at least one cylinder in an intake stroke or an expansion stroke at a timing when a rotation reference position is detected by the rotation detection means, and determines whether the identified cylinder is in a compression stroke or a compression stroke. 2. The cylinder discriminating apparatus for an internal combustion engine according to claim 1, wherein fuel is supplied to the identified cylinder at a time during an exhaust stroke. 3. The fuel supply control means according to claim 2, wherein when the rotation reference position is detected by the rotation detection means, one is in an intake stroke and the other is in an expansion stroke.
The two cylinders are simultaneously supplied with fuel when the one cylinder is in a compression stroke and the other cylinder is in an exhaust stroke. 3. The method according to claim 1, wherein the ignition plugs of the two cylinders are simultaneously activated at a time when the cylinder is near the compression top dead center and the other cylinder is near the exhaust top dead center. A cylinder discriminating device for an internal combustion engine. 4. When the combustion state is not detected by the combustion state detection means, the processing by the fuel supply control means, the ignition control means, the combustion state detection means, and the top dead center determination means is repeated. The cylinder discriminating device for an internal combustion engine according to any one of claims 1 to 3, wherein the device is configured to be executed.