JPS59200042A - Air-fuel ratio controller for engine - Google Patents

Abstract

PURPOSE:To make a secular change in an air-fuel ratio possible to be compensated, by making an engine operate on a high output just before the start of knocking in a high load, low speed range, while controlling a fuel injection quantity upon detection of a lag in the ignition timing. CONSTITUTION:A control device 9 consisting of a microcomputer and the like takes in each signal out of O2, speed output, suction air temperature, water temperature and suction pressure sensors 15, 10, 11 and 13, and performs feedback control by means of the O2 sensor 15 in a range where closed loop control is attainable. And, in a high load, low speed range, on the basis of a signal out of a knock sensor 1, the control device 9 makes an engine operate on a high output just before the start of knocking, while on the basis of a lag in the ignition timing detected in time of operation, that is, a knock critical point in the ignition timing comes to be uneven due to a secular change so that a fuel injection quantity is controlled via an air-fuel ratio compensating device 3 consisting of a driver 31 and a timer T132. Thus, unevenness in the air-fuel ratio due to said secular change can be effectively compensated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for an engine, which is equipped with closed-loop control means for feedback controlling the air-fuel ratio and open control means for controlling the air-fuel ratio in an open manner. In the region where knocking is likely to occur at low speeds (hereinafter referred to as the "knock region"), the engine is operated at the critical point for non-king to occur, while at the same time automatically compensating for air-fuel ratio deviations due to aging. The present invention relates to an EDGE air-fuel ratio control device equipped with a loop control means.

Various attempts have been made to compensate for air-fuel ratio fluctuations due to aging in automobile engines equipped with electronically controlled fuel injection devices.

For example, the one proposed in Japanese Patent Application Laid-Open No. 55-96339 is an example of this.

This system operates a microcomputer to perform learning control within the so-called feedback region, and changes the operating status of the machine based on the output signal of the 02 setter, which detects the oxygen concentration from the exhaust gas components. Accordingly, the preset fuel injection amount is compensated by a small amount, and when the air-fuel ratio is changing to the richer side than the preset value, the fuel injection amount is reduced to correct the air-fuel ratio toward the lean side, and When the air-fuel ratio changes to the lean side, the fuel injection amount is increased to correct this in the rich direction.

However, in this type of control device, the air-fuel ratio cannot be accurately controlled in the so-called enriched region, where the engine must be operated at high load with enriched air and fuel ratios, and this prevents the engine from constantly running the engine with the appropriate amount of fuel. It was difficult to expect it to operate under these conditions.

Therefore, in order to solve such inconvenience, the present applicant proposed enrich f
We have proposed a method in which learning control can be performed also in the enriched region based on the basic control value in the feedback region adjacent to F[.

However, this proposal also had difficulty in accurately controlling the air-fuel ratio in the enriched 1 region as required. .

In other words, since the air-fuel ratio in the enriched region is corrected based on the learning value obtained within the feedback region, it is a correction based on expectations, and the correction as requested is not achieved. It is difficult to say that there are
Particularly in areas where knocking is likely to occur, such as under high load and low rotation speeds, even within the enriched range, if the air-fuel ratio is not set as required, knocking will occur and proper engine output may not be obtained. It was.

The present invention was developed in order to solve the problems described above. In the feedback region where closed-loop control is possible, conventional control is performed, and in the open-loop region, it is High load low rotation area ("
The high-load, high-speed range where there is no risk of non-knocking (hereinafter referred to as the "unknock range") is divided into a high-load, high-speed range where there is no risk of non-knocking (hereinafter referred to as the "unknock range"). An air-fuel ratio control device that maintains output and compensates for variations in air-fuel ratio over time by controlling fuel injection amount based on the amount of ignition timing delay detected during operation. The purpose is to provide the following.

An embodiment of the present invention will be described below, and before entering into the detailed description, the principle of adjusting the air-fuel ratio within the knock region of the open loop control means of the present invention will be outlined.

In general, it is well known that under the same operating conditions, the more advanced the ignition timing of the Edge, the higher the output of the engine can be obtained. Non-king is more likely to occur.

Similarly, if we consider the relationship between knocking and air-fuel ratio under the same operating conditions, the richer the air-fuel ratio, the more likely non-king will occur, and conversely, the leaner the air-fuel ratio, the more likely knocking will occur. There is a tendency to become

Therefore, considering the case where the knocking critical point of the ignition timing has shifted somewhat in the direction of retardation from the beginning due to aging, when operating the engine at that ignition timing,
The air-fuel ratio has deviated towards the leaf compared to the initial setting value of the acid.
Moreover, in the opposite case, it means that there is a shift in the lynch direction.

In other words, by comparing the non-king critical point of the ignition timing, it is possible to determine the deviation direction of the air-fuel ratio due to aging, etc., and by repeatedly correcting this deviation, the engine is kept under the optimal conditions within the knocking region. It is possible to drive underneath.

Therefore, according to the open loop control means of the present invention, the ignition timing is shifted aJ to the critical point where non-king occurs within the knocking region where blind control was conventionally performed, and at the same time, this critical point is set in advance. If the air-fuel ratio has changed from the reference value, the fuel injection amount is corrected to compensate for the deviation in the air-fuel ratio, thereby allowing the engine to operate under optimal conditions.

Next, with reference to FIG. 1, the basic configuration of the open loop control means that constitutes the main part of the present invention will be explained.

Reference numeral 1 denotes knocking detection means including a knocking sensor that detects whether or not knocking occurs in the engine 6; Reference numeral 2 denotes an ignition timing adjustment means that adjusts the ignition timing in a direction to suppress knocking based on the knocking detection means 1. , 3 is an air-fuel ratio correction means that defines the pulse width of a fuel injection pulse that energizes the fuel injection valve and sets the fuel injection amount; 4 is a memory that stores a preset reference value for ignition timing; Means 5 is a comparison means for comparing the reference value stored in the storage means 4 with the optimum ignition time 1 set by the ignition timing adjustment means 2, and if a deviation exists as a result of the comparison, the deviation is The above-mentioned air-fuel ratio correction means is controlled in accordance with the above-described air-fuel ratio correction means, thereby increasing or decreasing the fuel injection amount and instructing correction of the air-fuel ratio.

When the knocking detection means 1 detects the occurrence of knocking, the ignition timing adjustment means 2 reduces the ignition timing control amount (delays the ignition angle) given in advance according to the operating state using a map, etc., to start the engine. Always operate at the optimum ignition timing, that is, at the critical point where knocking occurs.

On the other hand, in the knock region, the comparison means 5 compares the ignition timing adjustment means 2 with
When it is determined that the optimum ignition timing set by the above is on the delayed side from the preset reference value read out from the storage means 4, the basic fuel injection amount given according to the operating condition is increased in advance based on a map or the like. On the other hand, when the comparison means 5 determines that the optimum ignition timing is on the advanced side of the reference value read out from the storage means 4, it controls the air-fuel ratio correction means 3 by decreasing the basic fuel injection amount.

FIG. 2 is a schematic configuration diagram of an apparatus of the present invention using a microcomputer, which is constructed by combining the previously described open loop control means with a known closed loop control means.

The microcomputer 9 includes sensors 1, 10, 11, which will be described later, provided to know the operating state of the engine 6.
Ignition timing adjustment means 2 by inputting the outputs of 13, 15 and 17
, an I/Q interface for outputting a control signal to the air-fuel ratio correction means 3, and a central processing unit (CPU).
, a read-only Φ° memory (ROM), and a random e-access memory IJ (RAM), forming a basic structure in which these are connected by a data bus and an address bus.

In each number of the read-only memory, information regarding the fuel injection amount and ignition timing, which are set based on the engine rotational speed, the intake pressure P, and the ignition timing are recorded as a so-called basic control map. , the storage means 4 is also constituted by a read-only memory.

On the other hand, in each address of the random access memory, correction information that defines the amount of correction for the above-mentioned basic control amount is stored in the form of a correction coefficient, and this correction information is applied to the zone discrimination results by the computer 9. ■ Feedback correction amount & (KF/B) that increases or decreases the fuel injection amount used during feedback control, ■ Knock correction coefficient (KK) that increases or decreases the advance angle amount used within the knock region during open loop control. , (2) are each stored in an updatable manner as a learning correction coefficient (KL) for increasing or decreasing the fuel injection amount, which is used during learning control within the knock region.

The ignition timing adjustment means 2 includes an ignition coil that ignites the spark plug, a driver 21 that energizes the ignition coil, and a timer T222 that sets the ignition start time by the driver 21.
This ignition start time is determined by the TD of the piston.
It is defined by the amount of advance based on time point C, that is, by the set time t3 of timer T2.

The other air-fuel ratio correction means 3 includes a fuel injection valve, a driver 31 that energizes the injection valve, and a timer T132 that defines the operating time of the driver 31.
The fuel injection amount is determined by defining the pulse width of the fuel injection pulse, that is, the set time L2 of the timer T.

Here, each sensor that detects the operating state of the engine will be explained.

That is, the 02 sensor 15 disposed in the exhaust manifold 7 is activated only during feedback control, but the rotational output is increased by 10, the intake temperature sensor 11 disposed in the intake pipe 8, and the intake temperature sensor 11 disposed in the cooling pipe. water temperature sensor 13, exhaust pipe 8
The intake pressure sensor 17 disposed inside is operated during any control to set the basic control amount of fuel injection amount and ignition timing, and the correction amount for intake air temperature and cooling water temperature. Information is sent from time to time to the microcomputer 9.

On the other hand, the non-kink detection means 1 including the non-kink sensor is used to adjust the ignition timing when the engine operating region is in the knock region, and is therefore an essential part of the open-loop control means. It is a configuration requirement.

Next, a control program used to control the device of the present invention will be explained.

This program uses 1 to know the operating condition of the engine.
Each sensor 1-o, 11. i3. Starting with the ability to read out information necessary for control from 15°17),
The four control areas shown in FIG. 3 are divided into zones and half 11, and control is performed according to each control area. This zone discrimination is performed based on the following conditions.

(1) Feedback region This operation region is operated when the conditions that the intake pressure P'/J of the engine 6 (predetermined value P) is lower and the cooling water temperature W is higher than the predetermined value W. Basic correction of the basic control amount of fuel injection amount according to operating conditions,
In other words, the correction coefficients KFA, KFU for intake air temperature and cooling water temperature
The basic correction for ζ2 ignition noise H, that is, the correction amounts KSA and KSW for intake air temperature and cooling water temperature are calculated, and the lean angle of the air-fuel ratio is determined by the already mentioned 02 Cenoza 15. .

Then, based on the determination result by the 02 sensor 15, the feedback correction coefficient KF/B of the fuel injection amount is increased or decreased by a small amount to control the air-fuel ratio. (Step 1000 → l (113 → 101.4-1015 →
1016a or 1066b→1017→1018
-1002) (2) Open-loop based intake pressure P is a predetermined value P. If the load is higher than that, it will fall into this range. This @ region is divided into a knock region when the engine 6 rotation speed ne is higher than a predetermined rotation speed &no under high load and high rotation, and a knock region during high load and low rotation when the engine rotation speed ne is lower than the predetermined rotation speed no. The latter knock region is further divided into a learning region in which a control map that defines the amount of fuel injection amount correction is used, and a non-learning region in which such a control map is not used.

In the Anonok area, step Loll, step 10
The engine is ignited at the ignition timing t3 determined by the basic correction amount number calculated in step 12, and the fuel injection amount is determined based on the learning correction coefficient determined in the previous learning control in addition to the basic correction mentioned above. Correction for L is added. (Step 1000=1013-→1019~410
20--1027--see 1002) On the other hand, in the knock region (region where the conditions of P≧Po and ne≦no are satisfied), when the occurrence of knocking is not detected by the knocking detection means 1, the knocking occurs. Correction amount &I
(Increase K, and conversely, if knocking is detected, decrease knock correction amount & KK,
The engine is operated at the critical point where knocking occurs.

Then, in the learning area of this knock area, it is further determined whether the knock correction coefficients have become larger or smaller than a predetermined value (reference value) KKφ, and the learning correction coefficient KL is increased or decreased by a minute amount ΔKL. Ru.

In this way, the optimum value of the ignition timing is set within the knock region, and it is determined whether or not it is in the learning region, and if it is, the fuel injection amount is basicly corrected based on the knock correction coefficients. In addition to the amount, it is also corrected by the learning correction coefficient KK.
．． Further, if the learning area is not in the learning area, no correction is made to the basic correction amount of the fuel injection amount. (Step 1000--→
1013 → 1019 → 1021 → 102
2a or], 022 b→]023→1024
→1002 or 1026--41002) Here, the learning area satisfies the following conditions.

Next, the control procedure of the apparatus of the present invention will be explained with reference to the flowchart shown in FIG.

Step 1000 is the starting point, and after initial setting is performed in Step 1001, in Step 1002, when it is detected that the piston has reached the dead center, the process moves to Step 1003, and a TDC detection pulse is generated. At the same time, from the main time meso built in computer 9,
TDC time 1° is read.

In step 1004, the timer T in the air-fuel ratio correction means 3
1 and starts the injection (t2 means the injection time of the fuel injector, that is, the pulse width of the fuel injection pulse, and the injection is completed after t2). Then, in step 1005, the ignition timing is adjusted. A time t3 until ignition is set in a timer T2 of means 2. (This t3 means the ignition time before TDC.) Step 1006
Now, let's take a look at the previous TDC timetable, which is the difference from the above-mentioned time t1, that is, 1. -16, the rotation &ne is calculated.

Then, in step 1007, t. Update to tl.

Thereafter, in step 1008, the intake pressure P is read, and in step 1009, the fuel injection time t4 and the ignition timing L5 are determined based on the rotational speed ne and the intake pressure P from a control map stored in the read instruction memory in the computer. It is read as the basic control amount.

Then, the process moves to step 1010, where the cooling water temperature W and the intake air temperature A are read, and in step 1011, the intake air temperature correction coefficient KFA and the cooling water temperature correction coefficient KFLI for the fuel injection amount are calculated to determine the basic fuel injection amount. Further, in step 1012, an intake temperature correction coefficient KEIA and a cooling water temperature correction coefficient KSW for the ignition timing are calculated to perform basic correction for the basic ignition timing.

In this way, basic correction is made to the basic control amount according to the engine operating condition, and the process moves to step 1013, where the engine intake pressure P, that is, the engine load condition, is determined. It will be done.

That is, in step 1013, the predetermined value Po of the intake pressure P is
If the condition P≧Po is satisfied, the process moves to step 1019, and if this condition is not satisfied, the process moves to step 1014. In step 1014, the engine cooling water temperature is further set to the reference value W. It is determined whether the object is a dog or not, and if the condition is satisfied, it is confirmed that the object is in the feedback area and feedback control is performed.

Feedback control is a step of determining the output of the sensor 02 installed in the exhaust manifold 7]O15
If it is determined in step 1015 that the air-fuel ratio is rich, the process proceeds to step 1.0163,
On the other hand, if it is cut off in half, the process proceeds to step 101.6b where the feedback correction coefficient KF is calculated.
/B is increased or decreased by a minute amount, that is, ΔKF/B.

Then, in step 1017, fuel injection M: t-2
is calculated, and in step 1018, the ignition timing L3 is further calculated and known feed pack control is performed.

On the other hand, in Stella 7''1013, the condition P≧P is that the engine 6 is in a high-load operation region.

When is satisfied, the process moves to step 1019, where it is further determined whether the rotation 'ine of the engine 6 is equal to or smaller than the critical point no at which non-king occurs.

Then, when the condition ne≦6° in step 1019 is satisfied, it is confirmed that the knock area is present, and step 102
In step 1o21, information from the non-king detection means 1 is read, and the process proceeds to either step 1022a or step 1022'b.

That is, if the ignition timing is corrected by the ignition timing adjustment means 2 and knocking does not occur, the process proceeds to step 1022a, and if non-king occurs, the process proceeds to step 1022b, where the knock correction coefficient 1 is determined. Increased or decreased.

Here, the knock correction amount &KK defines the amount of advance of the ignition timing, and when the occurrence of knocking is detected by the knocking detection means l, the correction coefficient KK is decreased by a minute amount, ΔKK, and the amount of delay of the ignition timing is determined. In the opposite case, it is increased by a minute amount ΔKK to reduce the amount of ignition timing delay. Then, in step 1023, the engine speed ne, the intake pressure P1, the water temperature W1, the intake temperature A
It is determined whether the engine is within the learning @ range by reading various information.

Then, if it is determined in step l023 that the knock correction coefficient is within the learning area, the knock correction coefficient updated in step 1022a or step 1022b is larger than the predetermined value KKφ stored in the basic map within the learning area. It is further determined whether KK≦KKφ, that is, if the amount of correction by the non-king correction becomes large (meaning that the amount of delay in ignition timing becomes large),
The learning correction coefficient KL is increased by a minute amount ΔKT, and K
K ) KKφ In other words, when the amount of correction by the knocking correction becomes smaller (meaning that the amount of delay in ignition timing becomes smaller), KL is decreased by a minute amount ΔKI to increase or decrease the fuel injection amount.

In step 1026, thus step 1022 a
, or 1022b, the ignition timing t3 is determined according to the knock correction coefficient O obtained, and in step 1027, the injection amount t2 to which the learning correction coefficient KL is added is calculated. on the other hand,
Proceeding from step 1013 to step 1019, ne≦
If it is determined that the no condition is not met,
After confirming that it is in the unknocked area, step 10
The process proceeds to step 20, where the ignition timing t3 is calculated, and the process proceeds to step 102.
7, the fuel injection time t4 is set.

Further, the process moves from step 1013 to step 1014,
Here, even if it is confirmed that the condition W≧Wo is not satisfied, the same control as in the anonok region is performed.

Thereafter, information corresponding to the operating state of the engine is supplied from each sensor to the controller 9 from time to time, and the operating range of the engine is divided into '#II' and the ignition timing adjustment means 2 and air-fuel ratio are adjusted according to the same procedure as described in L. Control is performed by the correction means 3.

As can be understood from the following detailed description, the air-fuel ratio control device of the present invention makes it possible to control the air-fuel ratio according to the operating state of the engine, particularly in the non-king region within the open-loop control region. This is very useful because it allows high output to be obtained by advancing the ignition timing to the critical point where knocking occurs all the time, and at the same time effectively compensates for variations in the air-fuel ratio due to aging.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of the loop control means, and FIG. 2 is a block diagram showing an embodiment of the device of the present invention. FIG. 4 is a flowchart showing the control procedure of the device of the present invention. (Explanation of symbols) 1 knocking detection means, 2 ignition timing adjustment means,
3 air-fuel ratio correction means, 4 storage means, 5
・Means of comparison. Patent applicant: Toyo Kogyo Co., Ltd. Agent Patent attorney: Takashi Suzue Procedural amendment: Commissioner of the Japan Patent Office Kazuo Wakasugi 1, Indication of case: Japanese Patent Application No. 58-72554 2: Title of invention: Engine air-fuel ratio control device 3. Relationship with the case of the person making the amendment Patent applicant Toyo Kogyo Co., Ltd. 4. Agent 5. Date of amendment order Voluntary (1) Column for detailed explanation of the invention in the specification - Part of the description is as follows: Correct as shown below. ■Specification section 6 summer line 9 to question page line 13 “Generally, -
more likely to occur. '' should be corrected as follows. 1. Generally speaking, in the knock region, it is well known that the further the engine's ignition timing is advanced, the more output the engine can obtain, and the more advanced the ignition timing is, the more likely non-king will occur. ” ■Page 11 of the specification box, line 11 to line 12 of the same page, ``Ignition start time'' is corrected to ``Time until ignition j. ■Page 11 of the specification, line 13, `` Correct ``Ignition start time'' to ``Time until ignition.'' ■In the 8th line of page 12 of the specification, "exhaust pipe 8" is corrected to "intake pipe 8." (2) The statement ``No correction of fuel injection amount will be made'' on page 16, line 2 to line 3 of the same page of the specification will be corrected as follows. Article 2 - "No new correction is made to the basic correction amount of fuel injection amount, and the value learned in the previous learning area is used as is.j ■ Specification, page 16, line 18 to page 20 The line ``In step 1003, by the main timer T1'' is corrected to ``Proceed to step 1003, and by the main timer built in the computer 9.'' ■Page 17 of the specification, line 8 to line 9 of the same page “(this t2
means the ignition time before TDC. )” is deleted. ■ On page 20 of the specification, line 7 to line 8 of the same page, correct the statement "When no knocking occurs" to "J when knocking occurs." ■Page 20 of the specification, line 8 to line 9 of the same page: Correct the phrase "if non-knocking occurs" to "if knocking does not occur." [Phase] On page 20, line 14 of the specification, the phrase "decreasing" is corrected to "increasing." (2) In the specification, page 20, line 15 to line 16 of the same page, ``increase'' is corrected to ``decrease.'' @Page 21, line 6 of the specification, "KK≦KKφ" is 'K<> K KG
Correct to J. 0 of the specification, page 21, line 10, "Kyo>KKφ" is corrected to rKK≦niyuJ. (2) Attached drawings - Above -

Claims (1)

[Claims] When the operating state of the engine is in the feedback region,
A closed-loop control means that performs feedback control on the air-fuel ratio of the intake mixture supplied to the engine; and an open-loop control that performs open-loop control on the air-fuel ratio of the intake mixture supplied to the engine when the operating state of the engine is in an enriched region. an air-fuel ratio control device for an engine, the open-loop control means comprising: (a) knocking detection means including a non-king sensor for detecting whether knocking occurs in the engine;
3(b) Ignition timing adjustment that corrects the ignition timing to the retarded side when knocking occurs in the engine, while correcting the ignition timing to the advanced side when knocking does not occur to operate the engine at the optimal ignition timing. (c) storage means storing a preset reference value of ignition timing; and (d) comparing the optimum ignition timing obtained by the ignition timing adjustment means with the reference value stored in the storage means. (e) Based on the comparison result of the comparison means, when the optimum ignition timing is on the delayed side from the reference value, the amount of fuel injection during open loop control is increased, while the optimum ignition timing is increased; The air-fuel ratio correction means corrects the air-fuel ratio of the intake air-fuel mixture by reducing the fuel injection amount during open-loop control when the fuel injection amount is on the advance side of the reference value. Air-fuel ratio control device for engines.