JP2000073927A - Device for detecting combustion state of internal combustion engine - Google Patents

Abstract

(57) Abstract: A combustion state detection device based on an ion current accurately detects a combustion state during a throttle operation, that is, a cold hesitation, in order to determine a deterioration in drivability in a cold state. SOLUTION: An ion output (peak value of an output voltage of an ion current detection circuit) before a throttle operation is stored,
A value obtained by multiplying the ion output by a predetermined coefficient is used as a criterion value, and the frequency of occurrence of combustion (misfire frequency) JMF below the criterion value during the throttle operation is calculated, thereby calculating cold hesitation. Is detected.
As a value to be stored as the ion output before the throttle operation, a value subjected to a blunting process, that is, a so-called simulated value is adopted in consideration of the fluctuation of the ion output for each combustion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting a combustion state based on an ion current flowing in accordance with an amount of ions generated by combustion in a cylinder of an internal combustion engine.

[0002]

2. Description of the Related Art As one method of detecting the combustion state of an internal combustion engine, a method has been proposed in which an ion current corresponding to the amount of ions generated in a cylinder is measured, and the combustion state is detected based on the ion current. I have. That is, when a discharge is caused by the ignition plug and the air-fuel mixture in the cylinder burns, the air-fuel mixture is ionized. When a voltage is applied between both electrodes of the ignition plug while the mixture is in an ionized state, an ionic current flows. This ion current can be measured, and the combustion state can be detected based on the current value.

For example, Japanese Patent Laying-Open No. 6-249048 discloses an apparatus which can easily detect a misfire for each cylinder by calculating a combustion roughness value for each cylinder using an ion current. ing.

[0004]

Incidentally, the detection of the combustion state based on the ion current is performed at a predetermined time after the cold start of the engine, that is, until the air-fuel ratio sensor is activated and the feedback control based on the output is started. Is particularly effective during the period. Deterioration of drivability in a cold state includes a case where combustion in an idle state is deteriorated and a case where combustion in an idle state is good but hesitation occurs. Hesitation is the response delay of the vehicle when the accelerator pedal is depressed, that is, when the throttle valve is operated.
This refers to a temporary decrease in engine output that occurs during or shortly after the accelerator is depressed.

[0005] Such cold hesitation causes a decrease in the engine rotation speed. On the other hand, the decrease in the engine rotation speed is caused not only by misfire but also by an external factor (such as a clutch meet). It is difficult to detect cold hesitation. Therefore, it is conceivable to detect the combustion state during the throttle valve operation from the ion current that directly reflects the combustion state, and determine whether or not cold hesitation has occurred.

However, when the relationship between the ion current value and the combustion state is examined, the ion current value changes when environmental conditions such as humidity change or the spark plug deteriorates even when the combustion state is the same. Resulting in. Therefore, it is practically difficult to accurately detect the combustion state based on the ion current.

In view of the above problems, an object of the present invention is to provide a combustion state detecting device based on an ion current. It is an object of the present invention to provide an apparatus that can accurately detect hesitation.

[0008]

According to the present invention, there is provided an ion current detecting apparatus for detecting an ion current corresponding to an amount of ions generated by combustion of an air-fuel mixture in a cylinder of an internal combustion engine. Detecting means; pre-operation state storage means for calculating and storing a representative value of the ionic current detected by the ionic current detecting means before the throttle valve of the engine is operated; and operating the throttle valve of the engine. A combustion state for determining a combustion state during throttle valve operation based on an ion current value detected by the ion current detection means in a state in which the throttle valve is operating and a representative ion current value stored by the pre-operation state storage means. And a determination means for determining a combustion state of the internal combustion engine.

According to the present invention, it is preferable that the representative value of the ion current calculated by the pre-operation state storage means is an average value of the ion current detected by the ion current detection means.

Further, according to the present invention, it is preferable that the pre-operation state storage means calculates and stores a representative value of the ion current in an idle operation state of the engine.

Further, according to the present invention, it is preferable that the apparatus further comprises a fuel injection amount determining means for determining a fuel injection amount according to the combustion state determined by the combustion state determining means.

Further, according to the present invention, it is preferable that the fuel injection amount determining means determines the fuel injection amount in accordance with the combustion state and the opening speed of the throttle valve.

[0013]

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 combustion state detecting device according to the present invention. The internal combustion engine 1 is an in-line multi-cylinder four-stroke cycle reciprocating gasoline engine mounted on a vehicle. The engine 1 includes a cylinder block 2 and a cylinder head 3. A plurality of cylinders 4 extending in the vertical direction are arranged in the cylinder block 2 in parallel in the thickness direction of the drawing, and a piston 5 is accommodated in each cylinder 4 so as to be able to reciprocate. Each piston 5 is connected to a common crankshaft 7 via a connecting rod 6. The reciprocating motion of each piston 5 is converted into a rotational motion of a crankshaft 7 via a 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,
Above each valve 11, 12, an intake side camshaft 1 is provided.
3 and the exhaust-side camshaft 14 are provided rotatably. Cams 15 and 16 for driving the valves 11 and 12 are attached to the camshafts 13 and 14, respectively. Timing pulleys 17 and 18 provided at ends of the camshafts 13 and 14 are connected to a timing pulley 19 provided at an end of the crankshaft 7 by a timing belt 20.

The intake port 9 is connected to an intake passage 30 having an air cleaner 31, a throttle valve 32, a surge tank 33, an intake manifold 34 and the like. Air (outside air) outside the engine 1 is supplied to the intake passage 3 toward the combustion chamber 8.
0 sequentially passes through the respective parts 31, 32, 33 and 34. An idle adjustment passage 35 that bypasses the throttle valve 32 is provided with an idle rotation speed control valve (ISCV) 36 for adjusting the air flow during idling. Each intake port 9 is provided in the intake manifold 34.
An injector 40 for injecting fuel toward is mounted. The fuel is stored in a fuel tank 41, from which the fuel is pumped by a fuel pump 42, and a fuel pipe 4
3 and is supplied to the injector 40. Then, a mixture of fuel injected from the injector 40 and air flowing in the intake passage 30 is introduced into the combustion chamber 8 via the intake valve 11.

To ignite this mixture, an ignition plug 50 is attached to the cylinder head 3. At the time of ignition, the igniter 51 that has received the ignition signal controls the supply and cutoff of the primary current of the ignition coil 52, and the secondary current is supplied to the ignition plug 5 via the ignition distributor 53.
0 is supplied.

The burned air-fuel mixture is guided as exhaust gas to an exhaust port 10 via an exhaust valve 12. The exhaust port 10 has an exhaust manifold 61 and a catalytic converter 62.
The exhaust passage 60 provided with the above is connected. HC (hydrocarbon), which is an incomplete combustion component, is supplied to the catalytic converter 62.
And a three-way catalyst that simultaneously promotes the oxidation of CO (carbon monoxide) and the reduction of NO _x (nitrogen oxide) generated by the reaction of nitrogen in the air with unburned oxygen. . The exhaust gas thus purified in the catalytic converter 62 is discharged into the atmosphere.

The engine 1 is provided with various sensors. A water temperature sensor 74 for detecting the temperature of the cooling water of the engine 1 is attached to the cylinder block 2. An air flow meter 70 for detecting an intake air flow rate is attached to the intake passage 30. An intake air temperature sensor 73 for detecting the temperature of the intake air is attached near the air cleaner 31 in the intake passage 30.
In the intake passage 30, near the throttle valve 32, a throttle opening sensor 72 for detecting the rotation angle of the shaft is provided. When the throttle valve 32 is in the fully closed state, the idle switch 82 is turned on, and the throttle fully closed signal output from the idle switch 82 becomes active. The surge tank 33 is provided with a vacuum sensor 71 for detecting an internal pressure (intake pressure). An O ₂ sensor 75 for detecting whether the air-fuel ratio of the exhaust gas is rich or lean with respect to the stoichiometric air-fuel ratio is attached to a portion of the exhaust passage 60 upstream of the catalytic converter 62.

The distributor 53 incorporates two rotors that rotate in synchronization with the rotation of the crankshaft 7, and detects the crank angle based on the rotation of one of the rotors to detect the reference position of the crankshaft 7. (C
A) is provided with a crank reference position sensor 80 that generates a reference position detection pulse every 720 ° CA in terms of A), and detects a rotation speed of the crankshaft 7 based on the rotation of the other rotor. Crank angle sensor 81 that generates a rotation speed detection pulse for each CA
Is provided. The vehicle is provided with a vehicle speed sensor 83 that generates a number of output pulses per unit time in proportion to the rotation speed of the transmission output shaft, that is, the vehicle speed.

Engine electronic control unit (engine ECU) 90
Is a microcomputer system that executes fuel injection control, ignition timing control, idle speed control, and the like.
The ignition timing control is based on the engine speed obtained from the crank angle sensor 81 and signals from other sensors, comprehensively determines the state of the engine, determines the optimal ignition timing, and sends an ignition signal to the igniter 51. It is. The idle rotation speed control detects an idle state based on a throttle fully closed signal from an idle switch 82 and a vehicle speed signal from a vehicle speed sensor 83, and sets a target rotation speed determined by an engine coolant temperature from a water temperature sensor 74 and an actual rotation speed. The engine speed is compared with the engine speed, the control amount is determined so as to reach the target speed according to the difference, and the ISCV 36 is controlled to adjust the air amount, thereby maintaining the optimum idle speed. .

The fuel injection control basically calculates a fuel injection amount for achieving a predetermined target air-fuel ratio, that is, an injection time by the injector 40, based on the intake air amount of the engine, and adjusts the fuel injection amount to a predetermined crank angle. At this time, the injector 40 is controlled to inject the fuel. In addition,
The intake air amount of the engine is calculated from the intake air flow rate measured by the air flow meter 70 and the engine rotation speed obtained from the crank angle sensor 81, or the intake pipe pressure and the engine rotation speed obtained from the vacuum sensor 71. Is estimated by Then, air applied when the fuel injection amount calculation is based on the signal from the basic correction, O ₂ sensor 75 based on signals from various sensors such as the throttle opening sensor 72, intake air temperature sensor 73, coolant temperature sensor 74 Fuel ratio feedback correction, etc. are added.

Further, the engine 1 is provided with an ion current detection circuit 110 so that the combustion state can be detected based on the amount of ions generated in the cylinder after combustion. FIG. 2 is a diagram showing a circuit configuration of the ignition device and the ion current detection circuit 110. One end of a primary winding 52a of the ignition coil 52 is connected to a positive electrode of the battery 100, and the other end is connected to a collector of a switching transistor 51a in the igniter 51. The emitter of the transistor 51a is grounded, and an ignition signal is applied to its base. One end of the secondary winding 52b of the ignition coil 52 is connected to a diode 1
12 cathodes. The anode of the diode 112 is connected to the center electrode 50a of the ignition plug 50 provided for each cylinder via the distributor 53. The outer electrode 50b of the spark plug 50 is grounded.

The diode 112 and the distributor 5
3 is connected to a diode 114 and a constant voltage power supply 116.
And an ion current detection resistor 118. Therefore, a constant voltage is applied to the ignition plug 50 by the constant voltage power supply 116 during the ignition cycle. The connection point between the constant voltage power supply 116 and the ion current detection resistor 118 gives the output signal voltage of the ion current detection circuit 110. Then, the output of the ion current detection circuit is guided to the engine ECU 90.

Next, the ignition device and the ion current detection circuit 1
The operation of No. 10 will be described. First, when the ignition signal becomes high and the transistor 51a is turned on, a current flows through the primary winding 52a of the ignition coil. Next, when the ignition signal is turned low and the transistor 51a is turned off to cut off the primary current, the secondary winding 5 of the ignition coil 52 is turned off.
A high voltage is induced in 2b, and as a result, a spark discharge occurs in the spark plug 50. That is, when a negative high voltage is applied to the center electrode 50a of the ignition plug 50, spark discharge occurs between the center electrode 50a and the outer electrode (ground electrode) 50b, and the ignition coil secondary winding 52b A current circulates through the ignition plug 50 and the diode 112 to the secondary winding 52b.

The spark discharge at the spark plug 50 causes
When the mixture in the combustion chamber ignites and burns, the mixture is ionized. When the air-fuel mixture is in an ionized state, there is conductivity between both electrodes of the ignition plug 50. In addition, since a voltage is applied between both electrodes of the ignition plug 50 by the constant voltage power supply 116, an ionic current flows. That is, the ion current is supplied from the positive electrode of the constant voltage power supply 116 to the ion current detection resistor 118 and the ignition plug 50.
Then, the current flows through the diode 114 to the negative electrode of the constant voltage power supply 116. Then, a voltage of “ion current value × detection resistance value” appears at a connection point between the ion current detection resistor 118 and the constant voltage power supply 116, and the voltage is supplied to the ECU 90 as an ion current detection circuit output.

Note that, even in the same combustion state, the peak value of the output voltage of the ion current detection circuit (hereinafter, simply referred to as ion output) varies for each combustion. However, when the ion output is measured for a certain number of times of combustion in the same combustion state and the average value is obtained, the average value has a certain correlation with the air-fuel ratio. FIG. 3 is a characteristic diagram showing a relationship between an air-fuel ratio and an average value of ion outputs over a predetermined number of times. As shown in this figure, the ion output average value becomes maximum near the output air-fuel ratio (the weight ratio of air and fuel (about 12.5) at which the output becomes maximum), and the air-fuel ratio leaner than that also occurs. There is also a tendency for the air-fuel ratio on the rich side to decrease.

FIG. 4 is a time chart exemplifying the behavior of the throttle opening TA, the engine speed NE and the ion output VPK after the cold start. FIG. 4A shows the case where cold hesitation does not occur, and FIG. ) Show cases where cold hesitation occurs. Figure (A)
4B and 4B show a stage of TA = 0 before the throttle operation, a stage of TA ≠ 0 during the throttle operation, and a stage of TA = 0 after the throttle operation.

As shown in FIG. 4A, when cold hesitation does not occur, when the throttle opening TA increases with the throttle operation, the engine rotational speed NE also increases normally, and the ion output (ion The peak value VPK of the output voltage of the current detection circuit also takes a larger value than before the throttle operation with an increase in the amount of ions generated after combustion. On the other hand, as shown in FIG. 4B, when cold hesitation occurs, even if the throttle opening TA increases with the throttle operation, misfire occurs and the engine speed NE increases. Instead, the ion output VPK also takes a value close to zero.

Therefore, it is possible to detect cold hesitation using the difference in ion output between FIGS. 4A and 4B. However, as described above, even when the combustion state is the same, the ion current value changes due to a change in environmental conditions such as humidity or deterioration of the spark plug, even when the combustion state is the same. Therefore, according to the present invention, the ion output before the throttle operation is stored, and a value obtained by multiplying the ion output by a predetermined coefficient (for example, 0.5) is used as a determination reference value. The purpose is to calculate the frequency of occurrence of lower combustion, and thereby to detect cold hesitation.

As a value stored as the ion output before the throttle operation, it is preferable to adopt a value subjected to a blunting process, that is, a so-called simulated value, in consideration of the fluctuation of the ion output for each combustion. Thus, in the present invention,
Since the combustion state during the throttle operation is detected based on the ion current before and during the throttle operation, the influence of the plug state, humidity and other factors is eliminated, and the presence or absence of cold hesitation can be accurately determined. .
Hereinafter, a specific example of the processing will be described.

FIG. 5 is a flowchart showing a processing procedure of a cold hesitation detection routine executed by the ECU 90. This routine is executed at a predetermined crank angle for each ignition cycle. First, step 20
In 2, the peak value VPK of the output voltage of the ion current detection circuit 110 is detected as an ion output. Next, at step 204, it is determined whether or not it is in a section where cold hesitation should be detected, that is, whether or not it is within a predetermined time after the cold start. When it is not in such a detection section, this routine is ended. On the other hand, when it is in this detection section, the routine proceeds to step 206.

In step 206, it is determined whether or not the engine is in an idle state. When the engine is in the idle state, the routine proceeds to step 208, and when it is not in the idle state, the routine proceeds to step 216. In step 208, a throttle operation flag XT set in a step described later is set.
It is determined whether or not A is ON, and XTA =
When OFF, the process proceeds to step 214, while XTA =
When it is ON, the process proceeds to step 210.

Therefore, when this routine is executed in the idle state before the throttle operation after the cold start, the routine proceeds to step 214 via steps 202, 204, 206 and 208. Then, in step 214, the ion output smoothed value VPKAVE is updated by the calculation of VPKAVE ← VPKAVE * (1-d) + VPK * d. In this smoothing operation, the ion output smoothed value VPKAVE up to the previous time is weighted by “1-d”, the ion output VPK detected this time is weighted by d, a weighted average is calculated, and the weighted average is calculated. Ion output smoothing value VPKAVE
For example, 1/32 is adopted as the coefficient d. After execution of step 214, this routine ends.

On the other hand, when this routine is executed in a stage where the throttle operation is being performed after the cold start through the idle state, steps 202, 204 and 20 are executed.
After that, the process proceeds to step 216. And
In step 216, the throttle operation flag XTA is set to ON. Next, at step 218, the ignition count CIGT (initial value 0) is incremented. Next, at step 220, the ion output VPK detected this time is changed to the ion output smoothing value VP before the throttle operation.
It is determined whether or not the value is smaller than a determination reference value “VPKAVE * K” obtained by multiplying KAVE by a coefficient K (for example, 0.5). When “VPK ≧ VPKAVE * K”, it is considered that no misfire has occurred, and the routine ends. On the other hand, if "VPK <VPKAVE * K", it is considered that a misfire has occurred, and the routine proceeds to step 222, where the misfire count CMF (initial value 0) is incremented, and then this routine ends.

When this routine is executed after the cold start and the idle state again after the idle state and the throttle operation state, step 20 is executed.
The process proceeds to step 210 via 2, 204, 206 and 208. Then, in step 210, the misfire frequency J during the throttle operation is calculated by the following calculation: JMF ← (CMF / CIGT) * 100.
MF (unit%) is calculated. This misfire frequency JMF is
It indicates whether or not cold hesitation has occurred and its degree, and is used in an injection amount calculation routine described later. Next, at step 212, the throttle operation flag XTA is set to OFF, the ignition count CIGT is set to 0, and the misfire count CMF is set to 0, and the routine proceeds to step 214 described above.

FIG. 6 is a flowchart showing a processing procedure of an injection amount calculation routine executed by the ECU 90. This process is executed at a predetermined crank angle for each injection cycle. First, in step 302, a current engine operating state is detected from outputs from various sensors. Next, at step 304, based on the detected operating state, the amount of air G _{A taken} into the cylinder during the intake stroke is calculated. Next, in step 306, the G _F ← G _A / R _AF becomes operational, and calculates the fuel injection amount G _F to achieve the target air-fuel ratio R _AF in accordance with the operating state. Then, step 3
In 08, it converts the fuel injection amount G _F to the basic injection time TP.

Next, at step 310, by referring to a predetermined map according to the operation state, the warm-up increase coefficient FWL, the post-start increase coefficient FASE, and the wall adhesion correction amount FMW (the change in the intake pipe pressure in the transient operation state). Which changes with the change). The warm-up increase coefficient FWL and the post-start increase coefficient FASE are correction coefficients relating to steady-state increase, while the wall surface adhesion correction amount FMW is a correction amount related to transient increase.

Next, at step 312, it is determined whether or not combustion deterioration in the idle state is detected. The detection of deterioration of combustion in the idle state may be based on rotation fluctuation, as conventionally performed, or may be based on ion current. When the combustion deterioration in the idling state is detected, the process proceeds to step 314, and when it is not detected, the process proceeds to step 316. In step 316, it is determined whether or not the misfire frequency JMF during throttle operation calculated in the aforementioned cold hesitation detection routine exceeds a predetermined value, that is, whether or not cold hesitation is detected. When hesitation has not been detected, the routine proceeds to step 320, whereas when cold hesitation has been detected, the routine proceeds to step 318.

In step 314, which is executed when deterioration of combustion in the idle state is detected, a warm-up increase coefficient FWL, a post-start increase coefficient FASE, and a wall adhesion correction amount F
Let MW be ΔFWL, ΔFASE and ΔFMW, respectively.
Only increase. In this case, in consideration of the fact that combustion deterioration occurs in an idle state, that is, a steady state, ΔFWL / FWL> ΔFMW / FMW and ΔFWL / FMW
ASE / FASE> ΔFMW / FMW, and the increase rate of the steady-state increase correction coefficient is made larger than the increase rate of the transient increase correction amount.

On the other hand, in step 318 executed when cold hesitation is detected, a warm-up increase coefficient FWL, a post-start increase coefficient FASE, and a wall adhesion correction amount F
Let MW be ΔFWLh, ΔFASEh and ΔF, respectively.
Increase by MWh. In this case, in consideration of the fact that combustion deterioration in the transient state has occurred, ΔFWLh /
FWL <ΔFMWh / FMW and ΔFASEh / F
ASE <ΔFMWh / FMW, and the increase ratio of the transient increase correction amount is made larger than the increase ratio of the steady increase correction coefficient.

In step 320, which is executed last after step 314, 316 or 318, the basic injection time TP is corrected by the operation of T ← TP * (1 + FWL + FASE) * α + FMW to obtain the final injection time T. Note that α represents another correction coefficient. By such control, it is possible to avoid deterioration of drivability while suppressing deterioration of emission without excessively increasing the amount.

Next, a second modification of the first embodiment will be described.
An embodiment will be described. In the first embodiment, the misfire frequency is calculated by comparing the ion current before the throttle operation and the ion current during the throttle operation, and the presence or absence of cold hesitation is determined based only on the misfire frequency. . However, even when the combustion state before the throttle operation is the same, hesitation is more likely to occur when the accelerator pedal is rapidly depressed than when the accelerator pedal is depressed gently. That is, hesitation is more likely to occur as the throttle opening speed ΔTA shown in FIG. 7 increases.

Therefore, in the second embodiment, as shown in FIG. 8, a two-dimensional map of the throttle opening speed ΔTA and the misfire frequency JMF during the throttle operation is used to determine whether or not hesitation has occurred, and to determine whether or not hesitation has occurred. The degree is determined. Specifically, in step 316 of the injection amount calculation routine described above, the map shown in FIG. 8 is referred to based on ΔTA and JMF to determine the presence or absence and degree of hesitation. Step 31 executed when it is determined that hesitation is present
At 8, ΔFWLh, ΔFASEh and ΔFMWh are changed according to the degree of hesitation. That is,
As the degree of hesitation increases, ΔFWLh, Δ
FASEh and ΔFMWh are set to large values. In addition,
In FIG. 8, the degree of hesitation is set to two levels of "large" and "small", but it is possible to set more finely.

Although the embodiments of the present invention have been described above, the present invention is not limited to the embodiments, and various embodiments can be adopted. For example, various circuit configurations can be considered as the ion current detection circuit. Further, the method of calculating the fuel injection amount is not limited to the illustrated method.

[0046]

As described above, according to the present invention,
In the combustion state detection device based on the ion current, it is possible to accurately detect the combustion state during the throttle operation, that is, the cold hesitation, in order to determine the deterioration of the drivability at the time of cold.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of an electronically controlled internal combustion engine including a combustion state detection device 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 circuit.

FIG. 3 is a characteristic diagram showing a relationship between an air-fuel ratio and an ion output average value at a predetermined number of times.

FIG. 4 is a time chart illustrating behaviors of a throttle opening degree TA, an engine rotation speed NE, and an ion output VPK after a cold start; FIG. 4A shows a case where cold hesitation does not occur, and FIG. It is a figure which shows the case where an intervening hesitation occurs, respectively.

FIG. 5 is a flowchart showing a processing procedure of a cold hesitation detection routine executed by the ECU.

FIG. 6 is a flowchart showing a processing procedure of an injection amount calculation routine executed by the ECU.

FIG. 7 is a diagram for explaining a throttle opening speed ΔTA.

FIG. 8 is a diagram exemplifying a map for obtaining the presence / absence of hesitation and its degree from the throttle opening speed ΔTA and the misfire frequency JMF during throttle operation.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... In-line multi 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 31 ... Air cleaner 32 ... Throttle valve 33 ... Surge tank 34 ... Intake manifold 35 ... Idle adjust passage 36 ... Idle speed control valve (ISCV) 40 ... Injector 41 ... Fuel tank 42 ... Fuel pump 43 ... Fuel pipe 50 ... Ignition plug 51 ... Igniter 52 ... Ignition coil 53 ... Point Distributor 60 ... exhaust passage 61 ... exhaust manifold 62 ... catalytic converter 70 ... air flow meter 71 ... vacuum sensor 72 ... Throttle opening sensor 73 ... intake air temperature sensor 74 water temperature sensor 75 ... O ₂ sensor 80 ... crank reference position sensor 81 ... Crank Angle sensor 82 Idle switch 83 Vehicle speed sensor 90 Engine ECU 100 Battery 110 Ion current detection circuit

Continued on front page F-term (reference) 2G087 AA13 AA19 BB11 BB19 CC28 CC35 EE23 3G019 AB02 AC03 CD06 DB02 DC06 GA08 GA09 GA11 GA13 GA16 GA18 LA05 3G084 BA05 BA13 BA16 CA03 EB06 EB25 FA02 FA05 FA07 FA10 FA11 FA3 FA30 FA33 LA01 MA12 NA01 PA01Z PA07Z PA10Z PA11Z PC00Z PC09Z PD03Z PE01Z PE03Z PE08Z PF01Z

Claims (5)

[Claims] 1. An ion current detecting means for detecting an ion current corresponding to an amount of ions generated by combustion of an air-fuel mixture in a cylinder of an internal combustion engine; and said ion current in a state before a throttle valve of the engine is operated. A pre-operation state storage means for calculating and storing a representative value of the ion current detected by the current detection means; an ion current value detected by the ion current detection means in a state where an engine throttle valve is operated; A combustion state detection device for an internal combustion engine, comprising: a combustion state determination unit configured to determine a combustion state during a throttle valve operation based on an ion current representative value stored by a pre-operation state storage unit. 2. The ion current representative value calculated by the pre-operation state storage means is a smoothed value of the ion current detected by the ion current detection means.
A combustion state detection device for an internal combustion engine according to claim 1. 3. The combustion state detection device for an internal combustion engine according to claim 1, wherein said pre-operation state storage means calculates and stores a representative value of an ion current in an idle operation state of the engine. 4. The combustion state detection device for an internal combustion engine according to claim 1, further comprising a fuel injection amount determination unit that determines a fuel injection amount according to the combustion state determined by the combustion state determination unit. 5. The combustion state detecting device for an internal combustion engine according to claim 4, wherein said fuel injection amount determining means determines the fuel injection amount in accordance with a combustion state and an opening speed of a throttle valve.