JPS60233334A - Apparatus for controlling injection quantity of fuel in internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent misfiring and surging of an internal-combustion engine and to thereby improve the engine performance, by providing an air-fuel ratio signal generating means for detecting the concentration of a particular component contained in the exhaust gas of the engine, and judging that surging is caused when the integral value of the air-fuel ratio is greater than a reference value. CONSTITUTION:An air-fuel ratio signal generating means produces an air-fuel ratio signal representing the air-fuel ratio of an internal-combustion engine by detecting the concentration of a particular component contained in the exhaust gas of the engine. An integrating means integrates the absolute value of the difference in the level of the air-fuel ratio signals produced at each timing for a predetermined while when the engine operation is steady. Further, a comparing means compares the integral value with a reference value and judges that surging is caused when the integral value is greater than said reference value. By employing such an arrangement, it is enabled to prevent misfiring and surging of an engine and to thereby improve the engine performance.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a fuel injection amount control device for an internal combustion engine using a lean burn system.

BACKGROUND ART In recent years, a lean burn system has been adopted in which an internal combustion engine is operated at a lean air-fuel ratio in order to prevent exhaust pollution and to reduce fuel consumption. In other words, there is a system in which a lean sensor is provided in the exhaust pipe of the engine, and the output signal of the lean sensor is used to perform feedback control of the air/fuel ratio of the engine to an arbitrary value on the lean side. In such a lean burn system, an air-fuel ratio that does not have enough margin for the misfire limit due to NOx restrictions is adopted, and therefore, considering the worst tolerance of the lean sensor's durability, misfire,
This may lead to deterioration in driving performance such as surging.

Conventionally, misfire, surging, etc. have been detected using a G sensor or the like, which has resulted in a problem of increased manufacturing costs.

Purpose of the Invention In view of the above-mentioned problems of the conventional type, an object of the present invention is to detect surging using the lean/sen output signal, and when surging is detected, increase the amount of fuel to prevent misfires, surging, etc. The objective is to improve driving performance.

Structure of the Invention The structure of the present invention for achieving the above object is shown in FIG. In FIG. 1, the air-fuel ratio signal generating means detects the concentration of a specific component in the exhaust gas of an internal combustion engine and generates an air-fuel ratio signal indicating the air-fuel ratio of the engine, and the timing generating means generates timing at fixed time intervals. . The steady state determining means determines the steady state of the engine. The integrating means integrates the absolute value of the difference in air-fuel ratio signal level at each timing interval for a predetermined period when the engine is in a steady state, and the comparing means compares the integrated value with a predetermined value. As a result, when the integrated value is larger than the predetermined value, the fuel increasing means increases the fuel injection amount of the engine.

Example The present invention will be described in detail with reference to the drawings from FIG. 2 onwards.

FIG. 2 is an overall schematic diagram showing an embodiment of a fuel injection amount control device for an internal combustion engine according to the present invention. In Fig. 1, the surge tank 3 of the intake passage 2 of the engine body 1 has an intake passage 2.
A pressure sensor 4 is provided to detect the absolute pressure of intake air, and its output is supplied to an A/D converter 101 with a built-in multisolexer of a control circuit 10. A mixture sensor 6 is provided in the exhaust passage 5 of the engine body 1 . Since the output of the lean sensor 6 is obtained as a current output as shown in the output characteristics of FIG. 3, the control circuit 10
A/D
is supplied to converter 101.

The distributor has a crank angle sensor 8 whose shaft generates a pulse signal for detecting a reference position every 7200 degrees in terms of crank angle, and a pulse signal for detecting angular position every 30 degrees in terms of crank angle. A crank angle sensor 9 is provided that generates. Pulse signals from these crank angle sensors 8 and 9 are supplied to an input/output interface 103 of a control circuit 100.

Further, the intake passage 2 is provided with a fuel injection valve 11 for supplying pressurized fuel from a fuel supply system to the intake port for each cylinder.

The control circuit 10 is configured as a microcomputer, for example, and includes an A/D converter 101, an input/output current/voltage conversion circuit 102, an interface 103, and a CPU 105.
, ROMI 06, and RAMI O7 are provided.

104 is a drive circuit for driving the fuel injection valve 11. Incidentally, an interrupt occurs in the CPU 105 when the A/D converter 101 finishes A/D conversion, when the input/output interface 103 receives a pulse signal from the crank angle sensors 8 and 9, and so on.

The intake pressure data PM of the intake pressure sensor 4 and the output current value I4 of the lean sensor 6 are fetched by an A/D conversion routine executed at predetermined intervals and stored in a predetermined area of the RAM 1070. In other words, data PM in RAM 107
, It is updated every predetermined time.

FIGS. 4(G) and 4(B) are timing charts for explaining the present invention in detail. When the vehicle is traveling at a constant speed and the air-fuel ratio is relatively richer than the misfire limit, the output signal waveform of the lean sensor 6 hardly changes as shown in FIG. 4 (4). On the other hand, when the air-fuel ratio approaches the misfire limit while driving at a constant speed, as shown in Figure 4 (
As shown in B), the output signal waveform of the lean sensor 6 has a portion that protrudes toward the lean side. Tip 9: The change in waveform becomes large. The present invention detects surging by identifying the difference in change in the output waveform of the lean sensor, and increases the amount of fuel when surging is detected.

The operation of the apparatus shown in FIG. 2 will be explained with reference to the flowcharts shown in FIGS. 5 to 8.

FIG. 5 shows an A/D conversion routine, which is part of the main routine and is executed every predetermined period of time, for example, every 12 m5. That is, in step 501, the output value LNSR of the lean sensor 6 is taken in by the A/D converter 101 and stored in the RAM 107. At this time, other A/D converted values, such as intake pressure data PM, are also taken in from the A/D converter 101 and stored in the RAM 107.

In step 502, the absolute value S of the difference between the output value LN8RO taken in last time of the lean sensor 6 and the current output value LNSR is calculated. g, S←l LNSR-LNSROI - However, -1 is the output value L of the lean sensor 6 due to air-fuel ratio feedback
This is to eliminate changes in NSH as a dead zone. Therefore, -1 is not necessarily necessary. Step 503.5
In 04, S is guarded with 0. In step 505, the value S is added to the integrated amount ΔLN.

In step 506, it is determined whether the state is in a steady state.

Conditions for a steady state include, for example, the current air-fuel ratio A/F is below a predetermined value, the engine speed Ne is within a predetermined range, the intake pressure PM is within a predetermined range, and the change in intake pressure PM is For example, it must be within a predetermined range. As a result, if the state is not steady, the process proceeds to step 515 and the timer counter T is cleared.

Note that the timer counter T is, for example, a 32m5 counter, and in this case measures the duration of a steady state. The flow in step 515 proceeds to Stella f516 to clear the integrated amount ΔLN, and in step 517 LNSR
Prepare for next run as t-LNSRO, step 51
This routine ends at step 8.

If it is before 0.5 seconds have passed since the steady state has been reached, the flow in step 506 proceeds to step 507, and further proceeds to step 516. However, since the timer counter T is not cleared, the measurement of the steady state duration continues.

Next, when 0.5B has passed since the steady state has been reached, the flow in step 506 is changed from step 507 to step 5.
The process proceeds to step 517 via step 08. In other words, the cumulative amount ΔL
Since N is not cleared, the integration of the absolute value S calculated in step 502 starts.

Furthermore, when 1.5 m has passed since the steady state has been reached,
The flow at step 506 proceeds to step 509 via steps 507 and 508, where ΔLN←(ΔLNX15+ΔLN)/16 is calculated. Here, ΔLN indicates the average value of ΔLN for the past 15 times. Tsumashi, use the value ΔLN calculated this time in step 5.
It will be revised in 2009.

In step 510, surging detection is performed based on ΔLN≧X (constant value). If surging is not detected, the process advances to step 515 and returns to the initial state. If surging is detected, the process proceeds to step 511, where a constant value, for example 2, is added to the added value KLNADD of the lean air-fuel ratio correction coefficient KLEAN. Note that this constant value corresponds to, for example, 0.5 in terms of A/F. Then, KLNADD 4- KLNADD + 2. Furthermore, KLNADD is guarded at a maximum value, for example 4, in steps 512 and 513. In other words, the increase in fuel amount due to KLNADD is guarded by the A/F conversion value of 1. Next, in step 514, ΔLN is cleared. In other words,
Once surging is detected, ΔLN is cleared.

' Also, in the routine of FIG. 5, if the unsteady state occurs before 1.5 g has passed even if 0.58 has elapsed since the steady state has been reached, the flow at step 506 proceeds to step 515. Return to initial state.

In this way, in the routine of FIG. 5, i in the steady state
s, and when surging is detected, the added values KL and NADD of the lean air-fuel ratio correction coefficient KIJAH are increased within a predetermined limit.

The above-mentioned lean air-fuel ratio correction coefficient is for controlling the air-fuel ratio to a lean air-fuel ratio, and is set by the routine shown in FIG. 7, which will be described later.

FIG. 6 shows an injection amount calculation routine, which is executed at every predetermined crank angle. For example, if it is a synchronous injection method, 36
It is executed at a predetermined crank position every 0° CA, and in the case of a 4-cylinder independent injection system, it is executed at a predetermined crank position every 180° CA. In step 601, it is determined whether KLEAN is less than or equal to a predetermined value Y. In this case, Y corresponds to 20 in A/F conversion. When the air-fuel ratio is on the rich side such as tL A/F<20, there is no need to increase the amount of fuel, so it is not performed. If KLEAN≦Y, the addition value KLNADD is added to KLEAN in step 602,
Again in steps 603 and 604, set KLEAN to the maximum value Y
Guard with. In step 605, the intake pressure data PM
Then, the basic injection amount τ is calculated according to the rotational speed data Ne, and in step 606, the final injection amount τ is calculated. That is, τ←τ,・FAF・(KLEAN + K, ')・K
To 2+.

However, 3 for K and IK21 is a correction amount calculated based on other operating state parameters. And step 6
This routine ends at 07.

When the injection amount τ is calculated in this way, the injection start timing and the injection end timing are calculated by a routine not shown, and these timings are further set as the first. Ruto, 2J1, 2nd Conno'? The value of the lake reno star is subtracted and typed up every predetermined time. At this time, the injection start and end flags are set, the injection execution routine is executed, and as a result, fuel injection is executed.

The KLEAN calculation will be explained with reference to the routine shown in FIG. In step 701, KLEAN and PM are calculated from a one-dimensional map based on the intake pressure data PM, in step 702, KLEANNE is calculated from a one-dimensional map based on rotational speed data N8, and in step 703, KLEAN←KLEANPM is calculated. -KLE
Calculate ANNE. The calculated KLEAN is stored in the RAM 107 in step 704, and the calculated KLEAN is stored in the RAM 107 in step 705.
This routine ends.

Finally, the lean air-fuel ratio correction coefficient is used to set the air-fuel ratio to the lean side.

The air-fuel ratio FAF calculation will be explained with reference to the routine shown in FIG. The routine of FIG. 8 is executed at predetermined time intervals. In step 801, it is determined whether a feedback condition is met. The feedback conditions include various conditions such as startup, cooling water temperature, etc. If the condition is not met, the process advances to step 809 and FAF←1 is set. On the other hand, if the feedback condition is satisfied, the process proceeds to step 802 and performs air-fuel ratio feedback correction.

In step 802, the output current value I7 of the lean sensor 6 is
is the standard value! Determine whether the taste is good or not. ■If t≧IR, that is, when the air-fuel ratio is richer than the predetermined lean air-fuel ratio, it is determined in step 803 whether or not it is on the first side, that is, whether it is a change point from the rich side to the first side. Determine whether As a result, if it is on the first slope side, the skip amount A is added as FAF←FAF+A in step 805, and on the other hand, if it is not on the first slope side, FA is added in step 806.
A predetermined value 1a is added as F4-FAF+a. In addition,
Skip-1iA is set to 6, which is sufficiently larger than a, that is, A:>a.

In step 802, if t<IR, that is, if the predetermined lean air-fuel ratio is on the rich side, step 8
Proceed to 04. In step 804, it is determined whether or not it is the first rich side, that is, it is determined whether or not it is a change point from a lean side to a rich side. As a result, if it is the first rich side, the skip amount B is subtracted as FAF 4-FAF-B in step 807, whereas if it is not the first rich side, the skip amount B is subtracted as FAF 4-FAF-b. Subtract the quantification value. Note that the skip amount B is set to be sufficiently larger than b. That is, B>b.

The control shown in steps 806 and 808 is called integral control, and the control shown in steps 805 and 807 is called integral control.
The control shown in is called skip control. The air-fuel ratio correction amount FAF determined in steps 805 to 809 is stored in the RAM 107 in step 810, and this routine ends in step 811.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, as described in detail, surging can be detected using the output of a lean sensor without using a G sensor or the like, and when surging is detected, the amount of fuel is increased to prevent a misfire. , surging, etc. can be prevented and driving performance can be improved.

[Brief explanation of drawings]

FIG. 1 is an overall block diagram for explaining the present invention in detail, FIG. 2 is an overall schematic diagram showing an embodiment of the fuel injection amount control device for an internal combustion engine according to the present invention, and FIG. FIG. 4 is a timing diagram explaining the present invention in detail, and FIGS. 5 to 8 are the control circuit 10 of FIG. 2.
3 is a flowchart for explaining the operation of FIG. 1: Engine body, 4: Pressure sensor, 6: Lean sensor, 8
19: Crank angle sensor, 10 control circuit (micro controller), 11: Fuel injection valve. Patent Applicant Toyota Motor Corporation Patent Application Agent Akira Aoki Patent Attorney Kazuyuki Nishidate Patent Attorney Kenzo Hiraiwa Patent Attorney Akira Yamaguchi Patent Attorney Masaya Nishiyama Diagram 6 Procedural Amendment (Voluntary) 1988 Δ Manabu Shiga, Commissioner of the Japan Patent Office, September 27, 1998, Patent Application No. 89248, 2, Name of the invention, Fuel injection sensitivity control device for internal combustion engines 3, Person making the amendment Relationship to the case Patent applicant name: (320) ) Yota Automobile Co., Ltd. 4. Agent (4 others) 5. “Detailed explanation of the invention” column 6 of the specification to be amended 1” is extracted as “2nd”. Procedural amendment (voluntary) September 27, 1985 Manabu Shiga, Commissioner of the Patent Office1, Indication of the case 1989 Patent Application No. 892482, Name of invention Surging detection device for internal combustion engine (new name)3, Relationship with the case of the person making the amendment Patent applicant name (320J) Yota Jidosha Co., Ltd. 4, Agent 5, Subject of amendment 1) “Title of the invention” column in the specification 2) “Scope of claims” in the specification ” column 3) “Detailed explanation of the invention” column 4 in the specification “Brief explanation of drawings” column 5) Drawings (Figure 1) 6. Contents of amendment 1. Description 02) As per the attached sheet, the "title of the invention" is amended to "surging detection device for internal combustion engine". 3) A) Page 1, line 20 of the specification [Fuel 1'Jj injection amount control device] is corrected to ``Surging detection device.'' B) From page 2, line 19 to page 3, line 2 of the specification, ``Lean sensor output signal...'' is to provide a low-cost surging detection device. ” he corrected. C) IJl [Originally corrected to page 3, lines 14 and 15, "The fuel increase means causes..." t "It is considered that surging has occurred" OD) Specification, page 1, line 20
The line ``Fuel injection amount control'' and the first line of the fourth page are corrected to ``Surging detection''. E) Delete "Part of the main routine" on page 6, line 14 and line 15 of the specification. F) From line 13 on page 11 of the specification! Delete the 19th line "Injection start timing... As a result,". G] Page 14, line 14 of the specification, ``It can be done, and it is advantageous in terms of manufacturing cost.'' t Amend it to ``It can be done, and it is advantageous in terms of manufacturing cost. Also, for example.'' H) On page 14 of the specification, line 17, ``ga dekiru.'' is replaced with ``ga dekiru.''. ” he corrected. 4) Specification No. 14, line 20 and page 15, line 1 "Fuel injection amount control" t [Surging detection] amended 0 5) Attachment circular v0 7, List of attached documents l) Amended patent Claims 1 copy 2) Drawings (Figure 1) 1 copy 2, Claims

Claims (1)

[Claims] 1. Air-fuel ratio signal generating means for detecting the concentration of a specific component in the exhaust gas of an internal combustion engine and generating an air-fuel ratio signal indicating the air-fuel ratio of the engine; steady state determining means for determining the steady state of the engine; and a certain period of time. Timing generation means for generating interval timing; increasing the fuel injection amount of the engine when the engine is in a steady state and the absolute value of the difference in the air-fuel ratio signal level for each timing interval is integrated for a predetermined time; A fuel injection amount control device for an internal combustion engine, comprising a fuel increasing means.