JPH1077900A - Misfire detection control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge whether or not a misfire is generated by providing a memory for storing a plurality of fuel levels in regular order within the prescribed time and updating the stored fuel levels one by one. SOLUTION: A control means 70 detects a misfire by the fluctuation of the operating state of an internal combustion engine 2, and the control means 70 is provided with a memory 72 for storing a plurality of fuel levels in regular order within the specified time and updating the stored fuel levels one by one. That is, the memory 72 stores a plurality of fuel levels up to the number (n) (n>=1) within the prescribed time MFt successively into storage parts L1-Ln, and when the new fuel measured value is measured, the storage parts L1-Ln are moved up one by one to store the latest fuel level in the storage part Ln. At the time of detecting a misfire, whether this misfire is caused by abnormality of the internal combustion engine 2 and an ignition system or by the shortage of fuel is discriminated by the change of a fuel level before the detection of the misfire stored in the memory 72.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a misfire detection control device for an internal combustion engine, and more particularly to a control means for detecting whether a misfire has occurred due to a change in fuel level stored in a memory before the misfire detection when a misfire is detected. Judgment is made to distinguish between the misfire state when the internal combustion engine or the ignition system is abnormal and the misfire state when the fuel is insufficient, and to reliably prevent the abnormal lamp from being turned on due to the misfire even though the vehicle is normal. The present invention relates to a misfire detection and control device for an internal combustion engine that can be maintained at a low cost by taking measures only by changing a control program.

[0002]

2. Description of the Related Art In an internal combustion engine of a vehicle, a lean air-fuel mixture is operated by leaning the air-fuel mixture.
There are those that reduce the generation of harmful components of exhaust gas and improve fuel efficiency.

[0003] However, if the air-fuel mixture is too thin, combustion in the combustion chamber becomes poor, and unburned gas may flow to the exhaust system to cause misfire. The misfire that occurs is a factor that causes deterioration and breakage of the function of the catalyst, etc., and also causes air pollution by releasing unburned gas into the atmosphere.Therefore, a fuse sensor is installed downstream of the catalyst. When the temperature of the catalytic converter becomes higher than the set value due to a misfire and this fuse sensor detects the temperature condition, it is displayed on the meter or a warning lamp is lit on the panel to give the driver a misfire. Has been notified.

[0004] As the misfire detection control device for the internal combustion engine, there is one disclosed in Japanese Patent Application Laid-Open No. 8-61136. The drive control device for an internal combustion engine disclosed in this publication includes:
An internal combustion engine, a fuel tank for storing fuel used for the internal combustion engine, a fuel pump for discharging fuel in the fuel tank toward the internal combustion engine, and a fuel pipe for delivering fuel discharged by the fuel pump to the internal combustion engine And a fuel injection valve for injecting the fuel delivered by the fuel pipe into the internal combustion engine, and a misfire diagnosis means for performing diagnosis processing for misfire occurring in the internal combustion engine, wherein the misfire diagnosis means includes: A diagnosis stopping means for stopping the misfire diagnosis processing when the fuel remaining amount in the fuel tank becomes small or zero,
Misfires caused by low or zero remaining fuel in the fuel tank are excluded from misfire diagnosis targets to improve the accuracy of misfire diagnosis.

[0005]

In a conventional misfire detection control system for an internal combustion engine, the condition for misfiring despite the fact that the internal combustion engine is normal is as follows.
There is a shortage of gas, so-called fuel shortage.

[0006] The fuel level in the fuel tank changes depending on various operating conditions such as uphill, downhill, turning, and the like. If the fuel level in a flat-land running state is used as a condition, misfire monitoring is prohibited. Cannot be performed, and a misfire is detected.

As a result, turning on the abnormal lamp when a misfire is detected using the fuel level as a condition may confuse the driver, which is disadvantageous in practical use.

When an abnormal lamp is turned on due to misfire detection, it is necessary to perform a failure diagnosis at a dealer or the like. However, it is difficult to identify the cause of the misfire and the service cost is increased.

[0009]

SUMMARY OF THE INVENTION In order to eliminate the above-mentioned disadvantages, the present invention relates to a misfire detection control apparatus for an internal combustion engine having a control means for detecting misfires due to fluctuations in the operating state of the internal combustion engine. The control means is provided with a memory for sequentially storing a plurality of fuel levels in the memory and updating the stored fuel levels one by one. When a misfire is detected, a misfire occurs due to a change in the fuel level stored in the memory before the misfire detection. It is characterized in that a function of determining whether or not the occurrence has occurred is added to the control means.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION
When a misfire is detected, the control means determines whether a misfire has occurred due to a change in the fuel level before the misfire stored in the memory, and a misfire state when the internal combustion engine or the ignition system is abnormal and a misfire state when the fuel is insufficient. In this way, it is possible to reliably prevent the abnormal lamp from being turned on due to a misfire in spite of the fact that the vehicle is normal, and to maintain the cost at a low cost by only changing the control program.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

1 to 3 show an embodiment of the present invention. In FIG. 3, 2 is an internal combustion engine, 4 is a misfire detection control device, 6 is an air cleaner, 8 is an intake pipe, 10 is a throttle body, 12 is an intake manifold, 14 is an intake passage,
Reference numeral 16 denotes an exhaust pipe, and reference numeral 18 denotes an exhaust passage.

An intake pipe 8 interposed between the air cleaner 6 and the throttle body 10 to form a first intake passage 14-1.
An intake air temperature sensor 20 for detecting an intake air temperature is provided on the upstream side.

An intake throttle valve 22 is provided in a second intake passage 14-2 formed in the throttle body 10 and communicating with the first intake passage 14-1. The second intake passage 14-2 communicates with a third intake passage 14-3 formed in the intake manifold 12 via a surge tank 24. The downstream side of the third intake passage 14-3 is connected to a combustion chamber (not shown) of the internal combustion engine 2 via an intake valve (not shown). An exhaust passage 18 communicates with the combustion chamber via an exhaust valve (not shown).

Further, a throttle opening sensor 26 for detecting a throttle opening of the intake throttle valve 22 is provided, and an intake pipe pressure sensor 30 for detecting an intake pipe pressure via a filter 28 is provided in the surge tank 24.

The internal combustion engine 2 is provided with an exhaust gas recirculation EGR control valve 32 and an EGR determination valve 34.
Is also provided.

A canister 3 is provided between the fuel tank 36 and the intake system of the internal combustion engine 2.
8 is provided. That is, the surge tank 24 of the internal combustion engine 2 and the canister 38 are connected by the purge passage 40, and the purge duty valve 42
The canister 38 and the fuel tank 36 are connected by an evaporating passage 44, and a pressure valve 46 is provided in the middle of the evaporating passage 44. The pressure valve 46 is connected to a pressure valve control valve 48.

Further, an air opening passage 50 is provided in the canister 38, and an air opening control valve 52 is provided in the middle of the air opening passage 50.

The fuel tank 36 is provided with a fuel tank pressure sensor 54 for detecting the pressure in the fuel tank 36 and a level gauge 56 for detecting the amount of fuel in the fuel tank 36.

A water temperature sensor 58 for detecting the temperature of cooling water of the internal combustion engine 2 is provided, and a crank angle sensor 60 for detecting a crank angle of a crankshaft, not shown, that is, a crank angle is provided.

A catalyst 62 is provided in the exhaust passage 18 of the internal combustion engine 2, a front O 2 sensor 64 is provided in the exhaust passage 18 upstream of the catalyst 62, and an exhaust passage downstream of the catalyst 62 is provided. Rear O on the way 18
2 A sensor 66 is provided.

Further, the intake air temperature sensor 20, throttle opening sensor 26, intake pipe pressure sensor 30, EGR control valve 32, EGR determination valve 34, purge duty valve 42, pressure valve control valve 48, atmosphere opening control valve. 52, fuel tank pressure sensor 54, level gauge 56, water temperature sensor 58, crank angle sensor 60,
A front O2 sensor 64, a rear O2 sensor 66, and a distributor 68 are provided to be connected to the control means 70, respectively.

The control means 70 performs misfire detection based on fluctuations in the operating state of the internal combustion engine 2. The control means 70 sequentially stores a plurality of fuel levels within a predetermined time and stores the stored fuel levels. A memory 72 for updating one by one is provided.

That is, the memory 72 stores a plurality of fuel levels up to n (n> 1) within a predetermined time MFt as L1 to L
n, and when a new fuel measurement value is measured, the storage portions L1 to Ln
The stored fuel levels are updated one by one so that the fuel level is incremented by one and the latest fuel level is stored in the storage portion of Ln (see FIG. 1).

When a misfire is detected, the memory 72
The control means 70 has a function of determining whether or not a misfire has occurred due to a change in fuel level before the misfire stored in the controller 70.
Is provided in addition to.

More specifically, when the misfire is detected, the control unit 70 changes the fuel level stored in the memory 72 before the misfire is detected, for example, by 15% with respect to the capacity of the fuel tank 36.
Is compared with the minimum value MFmin of the fuel level stored in the memory 72, and when the minimum value MFmin is equal to or less than the fixed value MFL, it is determined that the misfire is invalid.

That is, in the internal combustion engine 2, a misfire occurs due to a shortage of fuel. When an engine abnormality lamp (not shown) is turned on when the fuel is insufficient, a driver or a worker performing maintenance performs a misfire. Cause cannot be identified.

For this reason, it is necessary to distinguish between misfire due to fuel shortage and misfire due to abnormality in the ignition system and fuel system of the internal combustion engine 2.

A misfire caused by a shortage of fuel is caused by a shortage of fuel simply when the fuel level is low, or when the vehicle is running, particularly when traveling on a rough road with severe irregularities or when making a sharp turn. And a misfire may occur.

When the misfire is detected, the control means 70 detects a momentary shortage of fuel caused by a change in the fuel level stored in the memory 72 before the misfire is detected, and determines that the misfire is invalid. .

Next, the operation will be described with reference to the control flowchart of FIG.

The internal combustion engine (E / G) 2 is driven (10
0) Then, the control program starts.

Then, n fuel levels (n> 1) within a predetermined time MFt are sequentially stored and stored in the storage portions L1 to Ln of the memory 72 (102), and whether a misfire has occurred or not is determined. Is determined (104).

If the determination (104) is NO, the process returns to the fuel level storage process (102), and the determination (104).
In the case of YES, the minimum value MFmin of the fuel level within the predetermined time MFt stored in the memory 72 is obtained (106).

After obtaining the minimum value MFmin of the fuel level, the minimum value MFmin of the fuel level and the fuel tank 3
6 is compared with a fixed value MFL set to a value of 15%, and the minimum value MFmin of the fuel level is determined to be a fixed value MFmin.
It is determined (108) whether or not it is less than L.

If the judgment (108) is YES,
The measured misfire is invalidated (110), and the process returns to the fuel level storing process (102). If the judgment (108) is NO, it is determined that a misfire has occurred, and the misfire counter MFco
Unt is incremented by 1 (112).

Then, the misfire counter MFcount is compared with the misfire determination number KMIS, and the misfire counter MFco
It is determined whether or not unt is equal to or greater than the misfire determination number KMIS (114). If this determination (114) is NO, the process returns to the fuel level storage process (102) and determines (1).
14) If YES, the internal combustion engine (E / G) 2
Is diagnosed as abnormal, and an abnormal lamp is lit to notify the driver (also referred to as “driver”) of the abnormality (116),
Let the control program be an end (118).

Thus, the misfire state when the internal combustion engine 2 or the ignition system is abnormal is distinguished from the misfire state when the fuel is insufficient, and the abnormal lamp due to the misfire is lit even though the vehicle is normal. Problems can be reliably prevented, and there is no fear of causing confusion to the driver or maintenance worker, which is practically advantageous.

Further, by adding a function of diagnosing an instantaneous fuel shortage at the time of turning of a vehicle or running on a rough road to the control means 70, it is possible to cope with it only by changing the control program, and the configuration is complicated. There is no fear of becoming
The cost can be kept low, which is economically advantageous.

Further, when a misfire is detected, the control means 70 compares a fixed value MFL set to a value of 15% with respect to the capacity of the fuel tank 36 with a minimum value MFmin of the fuel level stored in the memory 72. When the minimum value MFmin is equal to or less than the fixed value MFL, the misfire is determined to be invalid, so that the misfire factor can be determined by comparing the fixed value MFL with the minimum value MFmin of the fuel level. Thus, it is possible to reliably distinguish between the misfire state when the fuel is insufficient and the misfire state when the fuel is insufficient.

It should be noted that the present invention is not limited to the above-described embodiment, and various applications and modifications are possible.

For example, in the embodiment of the present invention, when the misfire is detected, the control unit 70 stores the fixed value MFL set to a value of 15% of the capacity of the fuel tank 36 and the memory 7.
2 is compared with the minimum value MFmin of the fuel level stored therein, and when the minimum value MFmin is equal to or smaller than the fixed value MFL, the misfire is determined to be invalid. (Also called "judgment value") MS
Standard deviation MFs of DV and fuel level stored in memory
d, and a function of determining that the misfire is invalid when the standard deviation MFsd is equal to or larger than the standard deviation determination value MSDV can be added to the control means.

That is, the processing (106) for obtaining the minimum value MFmin of the fuel level within the predetermined time MFt stored in the memory of FIG. 1 and the step of obtaining 15% of the minimum value MFmin of the fuel level and the capacity of the fuel tank. The value is compared with a fixed value MFL set as the value, and instead of the processing (108) for determining whether or not the minimum value MFmin of the fuel level is equal to or less than the fixed value MFL, the value is stored in the memory as shown in FIG. The standard deviation MFsd of the fuel level (L1 to Ln) within a predetermined time MFt is calculated (202), and it is determined whether or not this standard deviation MFsd is equal to or greater than the standard deviation determination value MSDV (20).
Perform 4).

When the misfire is detected, the control means compares a predetermined standard deviation judgment value (also referred to as "judgment value") MSDV with the standard deviation MFsd of the fuel level stored in the memory. When the standard deviation MFsd is equal to or larger than the standard deviation determination value MSDV, it is determined that the misfire is invalid, so that the standard deviation MFsd and the standard deviation determination value MSDV are determined.
Thus, the misfire factor can be determined by comparing the misfire state when the internal combustion engine or the ignition system is abnormal and the misfire state when the fuel is insufficient.

When a misfire is detected, a preset change amount determination value (also referred to as a "judgment value") DMFL is compared with a fuel level change amount DMF stored in a memory, and the change amount DMF is determined. A function of determining that the misfire is invalid when the value is equal to or more than the value DMFL can be added to the control means.

That is, the process (106) for obtaining the minimum value MFmin of the fuel level within the predetermined time MFt stored in the memory of FIG. 1 and the process of obtaining the minimum value MFmin of the fuel level and 15% of the fuel tank capacity. The value is compared with a fixed value MFL set as the value, and instead of the processing (108) for determining whether the minimum value MFmin of the fuel level is equal to or less than the fixed value MFL, the value is stored in the memory as shown in FIG. A change amount DMF is obtained from the maximum value MFmax and the minimum value MFmin of the fuel level within a predetermined time MFt by the formula DMF = MFmax-MFmin (302), and this change amount D
It is determined whether the MF is equal to or greater than the change amount determination value DMFL (304).

In this case, when the misfire is detected, the control means sets a predetermined change amount judgment value (also referred to as a "judgment value").
DMFL and fuel level change DM stored in memory
F, and the change amount DMF is compared with the change amount determination value DMF.
By determining that the misfire is invalid when L is greater than or equal to L, the misfire factor can be determined by comparing the change amount DMF with the change amount determination value DMFL, and the misfire state when the internal combustion engine or the ignition system is abnormal and the misfire when the fuel is insufficient. It can be reliably distinguished from the state.

Further, the control means has a function of comparing the fixed value MFL with the minimum value MFmin of the fuel level and a function of comparing the standard deviation judgment value MSDV with the standard deviation MFsd of the fuel level when a misfire is detected. And a function of comparing the change amount determination value DMFL with the change amount DMF of the fuel level, respectively, to improve the reliability of the misfire determination.

[0049]

As described above in detail, according to the present invention, in a misfire detection control apparatus for an internal combustion engine having a control means for detecting a misfire due to a change in the operating state of the internal combustion engine, a plurality of fuels within a predetermined time are provided. A memory for sequentially storing levels and updating the stored fuel levels one by one is provided in the control means, and when a misfire is detected, it is determined whether a misfire has occurred due to a change in the fuel level stored in the memory before the misfire detection. Because the function was added to the control means,
Distinguishes between a misfire state when the internal combustion engine or ignition system is abnormal and a misfire state when there is a shortage of fuel, and can reliably prevent the malfunction that the abnormal lamp is turned on due to the misfire even though the vehicle is normal. This is practically advantageous because there is no fear of causing confusion to the workers and maintenance workers. Further, by adding a function of diagnosing an instantaneous fuel shortage at the time of turning of the vehicle or running on a rough road to the control means, it is possible to cope with only by changing the control program, and the configuration may be complicated. The cost can be kept low, which is economically advantageous.

[Brief description of the drawings]

FIG. 1 is a control flowchart of an internal combustion engine misfire detection control device according to an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a misfire detection control device for an internal combustion engine.

FIG. 3 is a control flowchart of a misfire detection control device for an internal combustion engine according to another first embodiment of the present invention.

FIG. 4 is a control flowchart of a misfire detection control device for an internal combustion engine according to a second embodiment of the present invention.

[Explanation of symbols]

 2 Internal combustion engine 4 Misfire detection control device 6 Air cleaner 14 Intake passage 18 Exhaust passage 20 Intake temperature sensor 22 Intake throttle valve 26 Throttle opening sensor 30 Intake pipe pressure sensor 32 EGR control valve 34 EGR determination valve 36 Fuel tank 38 Canister 40 Purge Passage 42 Purge duty valve 44 Evaporation passage 46 Pressure valve 48 Pressure valve control valve 50 Atmospheric opening passage 52 Atmospheric opening control valve 54 Fuel tank pressure sensor 56 Level gauge 58 Water temperature sensor 60 Crank angle sensor 62 Catalyst 64 Front O2 sensor 66 Rear O2 sensor 68 Distributor 70 Control means 72 Memory

Claims (4)

[Claims] An internal combustion engine misfire detection control device having a control means for detecting a misfire according to a change in an operating state of the internal combustion engine, wherein a plurality of fuel levels within a predetermined time are sequentially stored and the stored fuel level is set to one. The control means is provided with a memory for updating individually, and at the time of misfire detection, a function of judging whether or not a misfire has occurred due to a change in fuel level before the misfire detection stored in the memory is added to the control means. A misfire detection control device for an internal combustion engine. 2. The control means compares a fixed value set based on the capacity of a fuel tank with a minimum value of a fuel level stored in a memory when a misfire is detected. The misfire detection control device for an internal combustion engine according to claim 1, which is control means for determining that the engine is invalid. 3. The control means compares a standard deviation judgment value set in advance with a standard deviation of a fuel level stored in a memory when a misfire is detected, and if the standard deviation is equal to or larger than the standard deviation judgment value, a misfire occurs. The misfire detection control device for an internal combustion engine according to claim 1, which is control means for determining that the engine is invalid. 4. The control means compares a predetermined change amount determination value with a change amount of a fuel level stored in a memory when a misfire is detected, and, if the change amount is equal to or greater than the change amount determination value, misfires. The misfire detection control device for an internal combustion engine according to claim 1, which is control means for determining that the engine is invalid.