JPH0565867A - Misfire detecting device for internal combustion engine - Google Patents

Abstract

PURPOSE:To accurately detect a misfire (FI misfire) by a cause related to a fuel system. CONSTITUTION:By comparing an ignition voltage value (D, D') with a comparison level (F, F') during a decision gate time (TDG), an FI misfire is decided. The comparison level (F, F') is set to a value of increasing an ignition voltage value (E, E') during measuring gate time (TMG) by times of a predetermined number(>1.0). When the ignition voltage value(D, D') exceeds the comparison level (F'), generation of the FI misfire is decided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detection device for an internal combustion engine, and more particularly to a misfire detection device for a fuel system.

[0002]

2. Description of the Related Art A spark plug is provided for each cylinder for igniting a fuel-air mixture drawn into a cylinder of an internal combustion engine. Usually, the high voltage generated in the ignition coil of the internal combustion engine is sequentially distributed to the ignition plugs of the respective cylinders via a distributor to ignite the fuel mixture. In this case, if the ignition by the spark plug is not normally performed, that is, if misfire occurs, various harmful effects occur. For example, there are adverse effects such as deterioration of driving performance, deterioration of fuel consumption, and further increase of catalyst temperature in the exhaust gas purification device due to post-combustion of unburned gas in the exhaust system passage. Therefore, it is absolutely necessary to prevent misfires that cause such harmful effects. The causes of this misfire are roughly classified into those related to the fuel system and those related to the ignition system. The former is related to the fuel system due to the lean or rich of the fuel mixture, and the latter is related to the so-called miss spark. Miss spark means that normal spark discharge does not occur in the spark plug. For example, there is a case where normal spark discharge is not performed due to smoldering or fogging of the spark plug due to adhesion of unburned fuel, or due to abnormality of the ignition circuit.

As a conventional misfire detecting device, for example, there is one disclosed in Japanese Patent Publication No. 51-22568. This utilizes the fact that the frequency of the damping oscillation voltage generated in each opening of the distributor contacts in the primary circuit of the ignition circuit is higher in the case of ignition than in the case of misfire.

[0004]

However, since the conventional misfire detection device detects only the frequency of the damping oscillation voltage generated in the ignition circuit, that is, the presence or absence of discharge between both electrodes of the spark plug, the misfire is detected. It was not possible to judge whether or not the cause was discharge, but the mixture was related to the fuel system such that the mixture did not ignite due to lean or rich, and it was not always satisfactory in terms of quick failure countermeasures.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a misfire detecting device for an internal combustion engine, which can detect whether or not the cause of the misfire is related to the fuel system. To do.

[0006]

In order to achieve the above object, the present invention provides an engine operating condition detecting means for detecting a value of an engine operating parameter, and an ignition timing is determined based on the value of the engine operating parameter. Signal generating means for generating an ignition command signal, ignition means for generating a high voltage for discharging an ignition plug provided in the engine based on the ignition command signal, and high voltage for the ignition means In a misfire detection device for an internal combustion engine having a voltage value detection means for detecting a voltage value at the time, whether or not a misfire has occurred by comparing an ignition voltage value after the ignition command signal is generated with a predetermined voltage value. A misfire determining means for determining is provided, and the misfire determining means has a period limiting means for limiting a comparison period in which the ignition voltage value and the predetermined voltage value are to be compared, and the ignition electric power in the comparison period. It is obtained so as to determine the misfire based on the magnitude relationship between the value and the predetermined voltage value.

The comparison period is a period near the end of the discharge period of the spark plug, a period after a predetermined period has elapsed since the ignition command signal was generated, or a predetermined period near the end of the discharge period of the spark plug or ignition. It is desirable to set the second predetermined period after the first predetermined period has elapsed since the command signal was generated.

Further, it is desirable that the predetermined voltage value is set according to the engine operating condition or the ignition voltage value. Further, the ignition voltage value used for setting the predetermined voltage value may be a voltage value during induction discharge of the spark plug.

Further, the ignition means has a primary side system path and a secondary side system path, and the secondary side system path is provided with a current suppressing means for suppressing a current in a direction opposite to a current at the time of spark plug discharge. Is desirable.

[0010]

The comparison period for comparing the ignition voltage value with the predetermined voltage value is limited, and the misfire state is determined based on the magnitude relationship between the ignition voltage value and the predetermined voltage value in the comparison period.

The predetermined voltage value is set according to the operating state of the engine or the ignition voltage value (preferably the voltage value during induction discharge).

A current in the opposite direction to the current at the time of spark plug discharge in the secondary system path of the ignition means is suppressed.

[0013]

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

FIG. 1 is a circuit diagram showing an embodiment of a misfire detecting device for an internal combustion engine according to the present invention. In the present embodiment, when a misfire related to the fuel system (hereinafter, abbreviated as "FI misfire") occurs, the value of the capacity discharge voltage in the latter stage of discharge is larger than that in the case of normal combustion, and therefore the capacity discharge is shown. The fact that the value of the area of the portion of the characteristic curve that is equal to or greater than the predetermined voltage value is also large is used.

In FIG. 1, a power supply terminal T1 to which a power supply voltage VB is supplied is connected to an ignition coil (ignition means) 1 composed of a primary side coil 2 and a secondary side coil 3, and a primary side coil 2 and a secondary side. The coil 3 is connected to each other at one end thereof,
The other end of the primary coil 2 is connected to the collector of the transistor 4 via a node N1 at which an ignition voltage (primary voltage) is generated, and the base of the transistor 4 is connected to an input terminal T2 to which the ignition command signal A is input. , Its emitter is grounded. The other end of the secondary coil 3 is connected to the center electrode 5a of the spark plug 5 via a node N2 where an ignition voltage (secondary voltage) is generated, and the ground electrode 5b of the spark plug 5 is grounded. .. Further, the node N1 is connected to the input side of the attenuator (voltage value detecting means) 6, and the node N2
Is connected to the input side of an attenuator (voltage value detecting means) 7, and the output sides of the attenuator 6 and the attenuator 7 are filter means 8 of an electronic control unit (hereinafter abbreviated as "ECU").
1, A / D converter 82 and filter means 83, A / D
It is connected to the CPU 85 via the converter 84. The attenuators 6 and 7 are voltage dividing means and divide the voltage with a predetermined voltage dividing ratio (for example, 1/1000 and 1/100). As a result, hundreds of volts on the primary side of the ignition coil,
On the secondary side, the voltage of tens of KV is lowered to about tens of V. Further, the CPU 85 is connected to the base of the transistor 4 via the drive circuit 86 to which the ignition command signal A is supplied, and detects various engine operating parameter values such as engine speed and engine load via the input circuit 87. It is connected to an operating parameter sensor (engine operating state detecting means) 9. The CPU 85 has a signal generating means for determining an ignition timing based on the engine operating state and generating an ignition command signal A,
And a misfire determination means for determining whether or not there is a misfire.

A distributor is provided between the secondary coil 3 and the center electrode 5a.
Are not shown in the figure.

FIG. 2 is a flow chart showing a program for executing the misfire detection operation of the circuit of FIG. 1, and this program is repeatedly executed at a predetermined cycle.

3 and 5 show an ignition voltage (primary voltage) V generated in the primary coil 2 of the ignition coil 1 and an ignition voltage (secondary voltage) V generated in the secondary coil 3 due to the generation of the ignition command signal A. 6 is a time chart showing an ignition voltage characteristic curve of the fuel cell, the solid line in FIG. 3 and FIG.
The ignition voltage characteristic curve at the time of misfire is shown.

Next, each ignition voltage characteristic will be described with reference to FIG.

First, the ignition voltage characteristic (characteristic indicated by the solid line) during normal combustion will be described. Immediately after the ignition command signal A generation time t0, the ignition voltage rises to a value that destroys the insulation of the fuel mixture (between the discharge gaps of the spark plugs) (curve a). For example, as shown in FIG. 3, when the value of the ignition voltage V exceeds the value of the reference voltage for normal ignition determination Vfire ₀ (V
> Vfire ₀ ) The insulation of the fuel mixture is destroyed, and the discharge voltage is almost constant from the capacity discharge state (discharge state for a very short time due to current of several hundred amperes) before the breakdown. (Curve b) (discharge period of about several milliseconds with current of about several tens of milliamperes). The induced discharge voltage rises as the pressure in the cylinder rises with the compression stroke after time t0. this is,
This is because the higher the pressure, the higher the voltage required for induction discharge. At the final stage of the induction discharge, the voltage between the spark plug electrodes becomes lower than the voltage for maintaining the induction discharge due to the reduction of the induction energy of the ignition coil, the induction discharge disappears and the capacity discharge state (the latter capacity discharge State). In the capacity discharge state, the voltage between the spark plug electrodes rises because it destroys the insulation of the fuel mixture again, but
The remaining energy of the ignition coil 1 is small and the voltage rise is slight (curve c). This is because the electric resistance between the plug gaps is low when combustion occurs, and is due to ionization of the fuel mixture during combustion.

Next, the ignition voltage characteristic (characteristic indicated by the dotted line) when the FI misfire occurs (when combustion does not occur) when the fuel mixture becomes lean or cut due to abnormality of the fuel supply system, etc. will be explained. To do. Immediately after the time t0 at which the ignition command signal A is generated, the ignition voltage V rises to a value at which the insulation of the fuel mixture between the spark plug electrodes is destroyed, but the value of the insulation breakdown voltage at this time is the air occupying the fuel mixture. Is included more than in the normal state, the dielectric strength of the fuel mixture becomes large, and since combustion does not occur, the fuel mixture is not ionized and the electrical resistance between the plug gaps is Since it becomes higher, it becomes higher than the voltage value during normal combustion (curve a ′). After that, the state shifts to the induction discharge state as in the normal combustion, but since the discharge resistance is larger than that in the normal combustion, the state shifts to the upper capacity discharge state earlier than the normal combustion (curve b ′). The value of the capacity discharge (the latter capacity discharge) generated at the final stage of the induction discharge is higher than that during normal combustion as shown in FIG. 3 because the breakdown voltage of the fuel mixture is larger than that during normal combustion. (Curve c ').

Next, the operation of the circuit shown in FIG. 1 will be described with reference to FIGS.

First, it is determined whether or not "1" is set in the IG flag (FlagIG) indicating whether or not the ignition command signal A is generated (step S1). "1" indicates that the ignition command signal A is generated. The process of setting the IG flag to "1" is performed by a routine different from the routine of FIG. 2, for example, an ignition timing calculation processing routine. Since "1" has not been raised before the ignition command signal A is generated, the determination in step S1 is negative, the process proceeds to steps S2, S3 and S4, and the timer of the ECU 8 (measures the time after the ignition command signal A is generated. Timer T) for the time Tmis ₀ (first predetermined period),
Tmis ₁ (second predetermined period) is set, and "0" is set to the fire flag (Flag fire) and the IG flag.
The operation of the flow is finished. The time Tmis ₀ is set to be longer than the time from the generation of the ignition command signal A to the end of the capacity discharge, and is the time from time t0 to t1 in FIG. The time Tmis ₁ is the time from time t0 to time t2.

The values of the times Tmis ₀ and Tmis ₁ are values read from a map or a table according to the engine operating state (engine operating parameter value), for example, engine speed, engine load, battery voltage, engine temperature, etc. Is. The same applies to Vfire ₀ and Smis ₁ described later.

Next, when the ignition command signal A is generated and the IG flag is set to "1", the process proceeds from step S1 to S5, and it is determined whether or not the value of the ignition voltage V exceeds the value of the reference voltage Vfire ₀ . Is determined (see FIG. 3). If V> Vfire ₀ , it is judged that normal ignition or FI misfire has occurred, and fire
"1" is set in the flag (step S6), and step S8
Move to. If V ≦ Vfire _0, the process proceeds to step S7, and it is determined whether or not “1” is set in the fire flag. When the fire flag is set to "1", V> Vfire ₀ is satisfied once, so the process proceeds to step S8, and it is determined in the subsequent processing whether normal ignition or FI misfiring. If "1" is not set in the fire flag, V> Vfire ₀ is not satisfied even once, so it is neither normal ignition nor FI misfire, or it must be in a state where it can be determined whether normal ignition or FI misfire. The determination is made and the operation of the flow of FIG. 2 is ended.

Next, in step S5, V> Vfire ₀
, Or in steps S5 and S7, V ≦ Vfire
_{If 0} and the fire flag is set to "1", it is determined in steps S8 and S9 whether or not the current time is between t1 and t2 (predetermined period), and the time t1
If between the t2, since it is time to be the normal ignition or FI misfire determination of whether to compare the value of the ignition voltage V and the predetermined voltage VMIS ₁ (step S10), and if V ≧ VMIS ₁ F
Determines that I misfire (step S11), and if V <Vmis _1, determines that the normal ignition rather than FI misfire. Predetermined voltage Vmi
s ₁ is set to a value capable of detecting the capacity discharge state indicated by the curve c ′ and sufficiently higher than the voltage value of the capacity discharge indicated by the curve c. If the current time is before time t1 in step S8, that time is not the time at which it can be determined whether normal ignition or FI misfire has occurred, so the operation of the flow of FIG. 2 ends. Also,
If the current time is after time t2 in step S9,
Since it is past the time at which it can be determined whether normal ignition or FI misfire has occurred, "0" is set to the fire flag and the IG flag (steps S3 and S4), and the operation of the flow of FIG. 2 ends.

Next, a second embodiment of the present invention will be described with reference to FIG.
Will be described with reference to FIG. 4 and 5, in FIG.
Differences from FIG. 3 are predetermined times Tmis ₀ ′ and Tmis ₁ ′ and reference voltages Vfire ₀ ′ and Vmis ₁ ′, which are shown in FIGS.
Tmis _0, Tmis ₁ and Vfire _0, corresponding respectively to the VMIS ₁ of. Since the operation shown in FIG. 4 is the same as the operation shown in FIG. 2, its description is omitted. Further, FIG. _{3, Tmis 0, Tmis 1,} Tmis 0 in FIG. 5 ', Tmis _1' is using the symbol of, TMIS _0, TMIS ₁ and Tmis ₀ ', Tmis _1' be different values from Good. Reference voltage Vfire ₀ , Vm
is ₁ is normally set to a value smaller than Vfire ₀ 'and Vmis ₁ '.

As can be seen from the above, in FIGS. 2 and 4, when the value of the ignition voltage V becomes V ≧ Vmis ₁ (V ≧ Vmis ₁ ') within a predetermined period from time t1 to t2. It is determined that the FI misfire has occurred, and the kind of the misfire, that is, the FI misfire can be accurately determined in this manner, so that it is possible to detect a failure location early and take appropriate countermeasures against the failure.

FIG. 6 is a diagram showing the construction of the misfire detection device according to the third embodiment of the present invention. The primary coil 2 and the transistor 4 of the ignition coil 1 are the same as those in the first embodiment of FIG. It is connected. The secondary coil 3 is connected to the center electrode 5a of the spark plug 5 via the distributor 12. A voltage sensor 13 that is electrostatically coupled to the connection line 14 (which forms a capacitor of several PF) is provided in the middle of the connection line 14 that connects the distributor 12 and the center electrode 5a. The output of the voltage sensor 13 is connected to the judgment gate circuit 22 and the measurement gate 23 via the input circuit 21. The input circuit 21 is composed of a voltage divider circuit, a buffer amplifier, etc., and outputs the detected ignition voltage V according to the detection value of the voltage sensor 13. The decision gate circuit 22 is a circuit that outputs the input signal as it is only during a predetermined decision gate period (TDG), and its output is connected to the non-inverting input of the comparator 27. The measurement gate circuit 23 is a circuit which outputs the input signal as it is only during a predetermined measurement gate period (TMG), and its output is connected to the peak hold circuit 24. The output of the peak hold circuit 24 is connected to the inverting input of the comparator 27 via the comparison level setting circuit 23. A reset circuit 26 for resetting the output of the comparison level setting circuit 23 at an appropriate timing is provided on the output side of the comparison level setting circuit 23.
Are connected. The output of the comparator 27 is connected to the misfire determination circuit 28.

In this embodiment as well, the ECU 8 (FIG. 1) for controlling the ignition timing of the engine is similarly provided. The circuit block 8a in FIG. 6 may be configured as a part of the ECU 8, but may be provided near the engine body. A timing signal that determines the gate period of the determination gate 22 and the measurement gate 23 and the reset timing of the reset circuit 26 is supplied from the CPU 85 of the ECU 8.

Next, the operation of the circuit shown in FIG. 6 will be described with reference to FIG.

7 (a), (b) and (c) show the ignition signal (A), the measurement gate signal (B) and the judgment gate signal (C), respectively. Is a gate period (TMG, TDG) for passing the input signal. These gate periods TMG and TDG are the time t when the ignition signal (A) is generated.
0 predetermined period Tmis ₂ ~Tmis ₅ elapsed after the time t3~t6
Is determined by. Further, FIG. 7D shows the detected ignition voltage (output of the input circuit 21) V (D) and the comparison level (output of the comparison level setting circuit 25) VCO during combustion.
MP (F) is shown. FIG. 6E shows the ignition voltage V (D ') and the comparison level VCOMP (F') at the time of misfire.

Measurement gate period TMG between times t3 and t4
In the meantime, the ignition voltage is supplied as it is to the peak hold circuit 24, and the peak value of the ignition voltage V (E and E'in FIGS. 9 (d) and 9 (e)) during the measurement gate period is held and the peak hold value is maintained. Are supplied to the comparison level setting circuit 25. The comparison level setting circuit 25 multiplies the input voltage by a predetermined number larger than the value 1, and outputs the comparison level VC after the measurement gate period TMG ends.
Output as OMP. Note that in FIG. 7, the comparison level VCOMP is at the start of the determination gate period TDG (time t
Although it is output in 5), it does not have to be adjusted to the time t5 as long as it is after the measurement gate period TMG ends. Also,
The measurement gate period TMG is set within the induction discharge period.

On the other hand, the non-inverting input of the comparator 27 is supplied with the ignition voltage V only during the judgment gate period between times t5 and t6, and is compared with the comparison level VCOMP by the comparator 27. The determination gate period TDG is the measurement gate period TM
Since it is set near the end of the discharge period after the end of G, the ignition voltage value (D) does not exceed the comparison level (F) during combustion as shown in FIG. At the time of misfire, the ignition voltage value (D ') exceeds the comparison level (F') as shown in FIG. As a result, the misfire determination circuit 28 causes the ignition voltage value (D ') to exceed the comparison level (F') (t7), as shown in FIG.
A high level signal is output at the same time, and a low level signal is output at the same time when the determination gate period ends. As a result, the occurrence of misfire can be detected.

The present embodiment is focused on the point that the ratio of the peak value of the capacity discharge voltage near the end of the discharge period to the value of the induced discharge voltage is much larger at the time of misfire than at the time of combustion. Comparison level VCOMP depending on the value
By setting, it becomes possible to accurately and stably detect misfire regardless of the engine operating state and changes with time of the spark plug and the like.

The peak hold circuit 24 may be replaced by an averaging circuit (integrating circuit).

Further, the judgment gate circuit 22 may be provided between the comparator 27 and the misfire judgment circuit 28 as shown in FIG.

Further, in the above-described embodiment, the judgment gate period TDG is set to a predetermined period near the end of the discharge period, but at the end time t6 of the judgment gate period TDG, the rotor head (not shown) of the distributor 12 has the following timing. It may be any time before the start of the segment (within a range of about 120 degrees in crank angle from ignition).

Further, as shown in FIG. 9, a diode 11 may be provided between the secondary coil 3 and the distributor 12. By providing the diode 11 in this manner, the electric charge accumulated between the diode 11 and the spark plug 5 is retained as it is at the time of misfire, and thus the detected ignition voltage is indicated by the broken line H in FIG. As shown, the high voltage state continues for a relatively long time. On the other hand, at the time of combustion, the ions accumulated in the vicinity of the electrodes of the spark plug 5 neutralize the charge accumulated between the diode 11 and the spark plug 5, so that the detected ignition voltage value is It changes in the same way as when not provided. That is, by providing the diode 11, the difference between the ignition voltage waveforms at the time of combustion and at the time of misfire becomes remarkable, and misfire detection can be performed more reliably.

Considering the characteristics of the diode 11 used in the embodiment of FIG. 9 described above, when the reverse breakdown voltage of the diode 11 is high, and when the stray capacitance between the diode and the plug is large, the piston moves upward. When the cylinder pressure decreases after the dead point, a breakdown (dielectric breakdown) may occur between the electrodes of the spark plug 5 early, and the detected ignition voltage V may decrease without being maintained at a high voltage (Fig. 1
0 (a)). When such a breakdown between the plug electrodes occurs, it cannot be distinguished from the decrease in the detected ignition voltage V due to the ion current during normal combustion, so the misfire determination may not be possible with the above method.

Therefore, as the diode 11, a breakdown is not generated between the plug electrodes (5 to 10 KV).
By using the Zener diode having the Zener voltage VZ of, the detected ignition voltage V can be maintained near the Zener voltage VZ for a long time at the time of misfire as shown in FIG. 10B, and misfire determination can be performed.

By using the diode 11 having a low reverse breakdown voltage, it is possible to obtain the same action and effect as in the case of using the Zener diode, but the applied voltage is within the normal operating range (exceeds the reverse breakdown voltage). The condition is that the performance is guaranteed when returning to the range (no range).

Further, as shown in FIG. 11, the breakdown voltage is 5 to 10 KV in parallel with the diode 11 having a high reverse breakdown voltage.
You may make it provide the gap element 11 'which is stable to some extent. With such a configuration as well, the detected ignition voltage at the time of misfire as shown in FIG. 10B can be obtained.

[0044]

As described in detail above, according to the misfire detection device of the first aspect, the comparison period in which the ignition voltage value and the predetermined voltage value are to be compared is limited, and the ignition voltage value and the predetermined voltage value in the comparison period are limited. Since the misfire state is determined based on the magnitude relationship with the voltage value, misfire related to the fuel system can be accurately detected, early detection of a failure location and appropriate failure countermeasures are possible.

Further, according to the misfire detecting device of the second to fifth aspects, since the comparison period is set to the latter stage of discharge, the misfire can be detected more reliably.

According to the misfire detecting device of the sixth or seventh aspect, since the predetermined voltage value is set according to the engine operating state or the ignition voltage value, even if the engine operating state changes. Accurately detect misfire.

According to the misfire detection device of claim 9,
Since the predetermined voltage value is set according to the ignition voltage value during the induction discharge of the spark plug, more accurate misfire detection can be performed.

According to the misfire detecting device of the tenth aspect, in the secondary system path of the ignition means, the current in the opposite direction to that at the time of spark plug discharge is suppressed.
The voltage of the secondary side path can be maintained in a high voltage state for a long time, and the misfire state can be determined more accurately.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a program for executing a misfire detection operation based on a primary side voltage.

FIG. 3 is a time chart showing an ignition voltage (primary side voltage).

FIG. 4 is a flowchart showing a program for executing a misfire detection operation based on a secondary side voltage.

FIG. 5 is a time chart showing an ignition voltage (secondary side voltage).

FIG. 6 is a diagram showing a configuration of a misfire detection device according to another embodiment of the present invention.

FIG. 7 is a time chart for explaining the operation of the apparatus of FIG.

FIG. 8 is a diagram showing a configuration of a modified example of the apparatus of FIG.

9 is a diagram showing a configuration of a modified example of the apparatus of FIG.

FIG. 10 is a time chart showing an ignition voltage.

FIG. 11 is a diagram showing a configuration of a modified example of the apparatus of FIG.

[Explanation of symbols]

1 Ignition coil 2 Primary side coil 3 Secondary side coil 5 Spark plug 6,7 Attenuator (voltage value detection means) 8 ECU 9 Various engine operation parameter sensors (engine operation state detection means) 12 Distributor 13 Voltage sensor 24 Peak hold circuit 27 Comparator 85 CPU (Signal Generation Means, Misfire Determination Means) 86 Drive Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eitaka Kuroda 1-4-1, Chuo, Wako-shi, Saitama Inside Honda R & D Co., Ltd. (72) Hideaki Arai 1-4-1, Chuo, Wako-shi, Saitama Incorporated company Honda R & D Co., Ltd. (72) Inventor Masatake Kanehiro 1-4-1 Chuo, Wako-shi, Saitama Prefecture Incorporated Honda R & D Co., Ltd. (72) Inventor Takashi Hisaki 1-1-4 Chuo, Wako-shi, Saitama No. Incorporated in Honda R & D Co., Ltd. (72) Inventor Shigeru Maruyama 1-4-1 Chuo, Wako-shi, Saitama Incorporated in Honda R & D Co., Ltd. (72) Inventor Shigeki Baba 1-4-1 Wako-Chu, Saitama No. Stock Company Honda Technical Research Institute

Claims (12)

[Claims] 1. An engine operating state detecting means for detecting a value of an engine operating parameter, a signal generating means for determining an ignition timing based on the value of the engine operating parameter to generate an ignition command signal, and the ignition command signal. An internal combustion engine having an ignition means for generating a high voltage for discharging an ignition plug provided in the engine, and a voltage value detection means for detecting a voltage value when the high voltage is generated in the ignition means. In an engine misfire detection device, a misfire determination means for determining whether or not a misfire has occurred by comparing the ignition voltage value after the ignition command signal is generated with a predetermined voltage value is provided, and the misfire determination means is the A misfire state is determined based on the magnitude relationship between the ignition voltage value and the predetermined voltage value in the comparison period, which has period limiting means for limiting the comparison period in which the ignition voltage value and the predetermined voltage value should be compared. A misfire detection device for an internal combustion engine, characterized by: 2. The comparison period is a period near the end of the discharge period of the spark plug.
A misfire detection device for an internal combustion engine as described above. 3. The misfire detection device for an internal combustion engine according to claim 1, wherein the comparison period is a period after a predetermined period has elapsed since the ignition command signal was generated. 4. The misfire detection device for an internal combustion engine according to claim 1, wherein the comparison period is a predetermined period near the end of the spark plug discharge engine. 5. The misfire detection device for an internal combustion engine according to claim 1, wherein the comparison period is a second predetermined period after the first predetermined period has elapsed since the ignition command signal was generated. 6. The misfire detection device for an internal combustion engine according to claim 1, wherein the predetermined voltage value is set according to an operating state of the engine. 7. The misfire detection device for an internal combustion engine according to claim 1, wherein the misfire determination means has a reference level setting means for setting the predetermined voltage value according to the ignition voltage value. 8. The reference level setting means comprises a smoothing means for smoothing the ignition voltage, and an amplifying means for amplifying an output of the smoothing means at a predetermined amplification factor. Internal combustion engine misfire detection device. 9. The smoothing means of the reference level setting means comprises:
9. The misfire detection device for an internal combustion engine according to claim 8, wherein the ignition voltage during induction discharge of the spark plug is smoothed. 10. The ignition means has a primary side system path and a secondary side system path, and the secondary side system path is provided with a current suppressing means for suppressing a current in a direction opposite to a current at the time of spark plug discharge. The misfire detection device for an internal combustion engine according to any one of claims 1 to 5, wherein: 11. The misfire detecting device for an internal combustion engine according to claim 1, wherein the ignition voltage is a primary side voltage of an ignition coil. 12. The misfire detection device for an internal combustion engine according to claim 1, wherein the ignition voltage is a secondary voltage of an ignition coil.