JPS61192836A - Ignition timing and air/fuel ratio control method for internal-combustion engine - Google Patents

Abstract

PURPOSE:To achieve reliable ignition by temporarily leading the ignition timing upon decision of abrupt acceleration from fuel cut while enriching the air/fuel ratio and lowering the secondary demand voltage in the ignition system. CONSTITUTION:It is decided whether a flug indicating fuel cut is set for every setting time (4mS, for example) through ECU42 under operation of engine. If the answer is YES to detect open condition of throttle valve 14 through a throttle opening sensor 16, fuel reset is executed. Then the time from fuel reset to full-open of throttle is counted through a counter and upon abrupt opening of throttle where the count is lower than predetermined leverl, the firing timing is temporarily led to enrich the air/fuel ratio thus to lower the secondary demand voltage in the ignition system to achieve reliable ignition thus to prevent knocking.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a method for controlling the ignition timing and air-fuel ratio of an internal combustion engine, and is particularly suitable for use in automobile engines equipped with electronically controlled fuel injection @ military, and is suitable for use when a predetermined fuel cut condition is met. The present invention relates to a method for controlling ignition timing and air-fuel ratio of an internal combustion engine.

[Conventional technology]

2. Description of the Related Art One of the methods for supplying an air-fuel mixture at a predetermined air-fuel ratio to combustion in an internal combustion engine such as an automobile engine uses an electronically controlled fuel injection device. This is achieved by disposing injectors for injecting fuel into the engine, for example, in several engine cylinders in the intake manifold, and by controlling the opening period W8 of the injector according to the operating state of the engine. The air-fuel mixture is supplied to the engine for combustion. In this electronically controlled fuel injection system, the basic injection amount is usually determined according to the basic operating condition of the engine such as the engine load and engine speed detected from the engine intake air amount or intake pipe pressure. Various increases and decreases due to signals input from sensors installed in each part of the engine.
The amount is added to determine the effective injection 114m, and the fuel injection is executed. Also, reducing hydrocarbons in exhaust gas,
In order to improve fuel efficiency and prevent catalyst overheating due to reactions of unburned fuel within the catalyst, fuel injection is generally stopped during deceleration to perform a so-called fuel cut. This fuel cut during deceleration is normally performed when the throttle valve is in the full state and the engine speed Ne is greater than or equal to the fuel cut speed N(i) determined according to the engine cooling water temperature, for example. Stop fuel injection, while
Whether the engine rotation speed Ne becomes equal to or less than the fuel cut return rotation speed Nf set lower than the fuel cut rotation speed NO;
Alternatively, when the throttle valve is opened, normal fuel injection is performed to achieve the set air-fuel ratio.

[Problems to be Solved by the Invention] On the other hand, in general, in spark-ignition internal combustion engines, the secondary voltage required to ignite the air-fuel mixture (hereinafter referred to as "required voltage") changes depending on the operating state of the engine. If this required voltage is too high, normal ignition cannot be performed, resulting in poor drivability and damage to ignition devices such as spark plugs and distributors. This required voltage becomes higher as the air-fuel ratio becomes leaner, the load becomes higher, and the ignition timing becomes delayed, and the required voltage becomes higher as the spark plug temperature becomes lower. For this reason, the combustion internal pressure increases, the ignition timing shifts to the retarded side, and there are many problems with the required voltage when accelerating suddenly at full throttle during fuel cut when the air-fuel mixture is lean. No measures were taken. - As a structure similar to the present invention, the applicant has already proposed in Japanese Patent Application No. 58-18678, which advances the ignition timing after detecting sudden acceleration to prevent a decrease in output and ensure acceleration performance. Although this method has proposed a method for improving fuel efficiency, it does not take into account the required voltage like the present invention. OBJECT OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and provides an internal combustion engine that can lower the required voltage during sudden acceleration after a fuel cut, and therefore can reliably ignite. The purpose of the present invention is to provide a method for controlling ignition timing and air-fuel ratio. [Means for Solving the Problems] The present invention provides an ignition timing and air-fuel ratio control method for an internal combustion engine in which a fuel cut is performed when a predetermined fuel cut condition is met, the summary of which is shown in FIG. As shown in the figure below, the procedure for determining whether or not there is a sudden acceleration state after a fuel cut, and the procedure for determining whether or not there is a sudden acceleration state after a fuel cut, and when the ignition timing is temporarily advanced and the air-fuel ratio is enriched, the ignition system The above object is achieved by including a step of lowering the secondary required voltage of. Also, the present invention actually fits! f14! In this method, both the advance of the ignition timing and the enrichment of the air-fuel ratio are performed by first changing them to the initial value and then gradually attenuating them, thereby achieving optimal ignition timing control and Air-fuel ratio control is performed.

[Effect]

In the present invention, during sudden acceleration after fuel cut, the ignition timing is temporarily advanced and the air-fuel ratio is enriched, so that the required voltage can be lowered and ignition can be reliably performed. In other words, if the ignition timing is advanced independently, there is a possibility that knocking will occur, but by enriching the air-fuel ratio at the same time, this can be prevented, and the effect of lowering the end voltage is also due to the advance control of the ignition timing. It will be larger than if only. The reason why the ignition timing is advanced and the air-fuel ratio is enriched only during sudden acceleration is that during sudden acceleration, the load becomes high and the required voltage increases before the plug temperature rises, but gradually When the load becomes high, the increase in plug temperature catches up with the increase in load, so the required voltage does not become so high and correction is not required.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an automobile engine equipped with an intake air amount sensing type electronically controlled fuel injection device, in which the ignition timing and air-fuel ratio control method according to the present invention are adopted, will be described in detail with reference to the drawings. The overall configuration of this embodiment is as shown in FIG. An air meter 12 for detecting air pressure, a throttle valve 14 equipped with a throttle opening sensor 16, a surge tank 18, and an injector 22 for intermittently injecting fuel toward the intake boat are provided. An intake manifold 24 and an intake valve 26 are provided. The throttle opening sensor 16 includes a throttle valve 14
The throttle valve 14 includes an idle switch that is turned on when the throttle valve 14 is fully closed, and a full open switch that is turned on when the throttle valve 14 is fully open. Further, an exhaust valve 28 and an exhaust manifold 30 are disposed in an exhaust passage for discharging exhaust gas formed by combustion within the engine combustion chamber 10A. Further, the spark plug 32 disposed in the engine combustion 110A' is provided with a distributor 3 that moves with the engine rotation and distributes the ignition secondary voltage to each cylinder of the engine.
4 is connected. This destination repeater 34 has
Rotation angle sensor 36 for detecting engine speed Ne
is built-in. Further, an ignition coil 40 that generates a high-voltage ignition secondary voltage according to the ignition-secondary voltage generated by the igniter 38 is connected to the distributor 34 . an intake air amount signal output from the air flow meter 12; a throttle opening signal output from the throttle opening sensor 16;
The rotation angle signal etc. output from the rotation angle sensor 36 is input to an electronic control unit (hereinafter referred to as ECLJ) 42, where various arithmetic processing is performed, and then the injector 22
A valve opening time signal for controlling the fuel injection device is output to the igniter 38, and an ignition command signal for controlling the ignition timing is output to the igniter 38. As shown in detail in FIG. 3, the ECu 42 includes an input interface 42A for inputting the outputs of the air flow meter 12, rotation angle sensor 36, throttle opening sensor 16, etc., and a central processing unit for performing various calculation processes. A unit (hereinafter referred to as CPU) 42B, a random access memory (hereinafter referred to as RAM) 42C for temporarily storing calculation data, etc., and a read-only memory (hereinafter referred to as RAM) for storing control programs etc. Hereinafter referred to as ROM18)42D,! : and an output interface 42E for outputting the calculation results of the CPU 42B (7) to the injector 22 and igniter 38. The effects of the embodiment will be explained below. Control of the ignition timing and air-fuel ratio in this embodiment is executed according to the flowchart shown in FIG. That is, step 11 is performed every time a set time elapses, for example, 4 milliseconds.
The flag f c enters 0 and indicates that the fuel is being cut.
Determine whether ut is set. If the determination result is negative, that is, if it is determined that fuel cut is not in progress, the process proceeds to step 112, where it is determined whether a flag fλ indicating that the idle switch is on is set. If the judgment result is positive, throttle valve 1
4 is determined to be in a fully closed state during deceleration,
Proceeding to step 114, the engine rotation speed Ne determined from the output of the rotation angle sensor 36 is determined to be the fuel cut rotation speed No.
It is determined whether or not the above is satisfied. If the determination result is positive, the process advances to step 116 and the fuel cut flag rc is set.
ut is set, fuel cut is performed, and this routine is exited. On the other hand, when the judgment result of step 112 is negative and it is judged that the throttle valve 14 is open and the operation is normal, or the judgment result of step 114 is negative and the engine rotational speed is When it is determined that Ne is less than the fuel cut rotation speed N0, the process proceeds to step 118, and it is determined whether a flag fd indicating that the time from fuel return to full throttle opening is being counted has already been set. . If the determination result is negative, the process proceeds to step 120, and it is determined whether a flag fa indicating that the correction according to the present invention after restoration is already being executed is set. If the determination result is negative, the routine exits directly. On the other hand, when the determination result in step 110 is positive and it is determined that the fuel cut is already in progress, the process proceeds to step 130, and the idle switch-on flag rfl is
Determine whether j2 is set. When the determination result is positive and it is determined that the throttle valve 14 is closed, the process proceeds to step 132, and the engine rotation speed N
It is determined whether e is equal to or greater than the fuel cut return rotation speed Nr (<Nc). If the determination result is positive, the routine exits directly. On the other hand, when the determination result in step 130 is negative and it is determined that the throttle valve 14 was opened during the fuel cut, or when the determination result in step 132 is negative and the throttle valve 14 is opened during the fuel cut, the engine When it is determined that the rotational speed Ne has become less than the fuel cut return rotational speed In, the process proceeds to step 134, and the flag fd is set during the recovery→total W@question count. Next, the process proceeds to step 136, where RA is used to count the time from return to full throttle opening.
MCd is cleared, and in step 138, the 7 lag fCu1t during fuel cut is reset so that fuel injection is restarted, and this routine exits. On the other hand, if the determination result in step 118 is positive,
That is, when it is determined that the time from return to full open throttle is being counted, the process proceeds to step 140, and the RAMCd for counting the time from return to full open is incremented. Next, the process proceeds to step 142, where it is determined whether the count value of RAMCd is less than or equal to a set value, for example 75 corresponding to 0.3 seconds. The reason why we set the time from when the fuel cut ends to when the full open switch is turned on to be within 0.3 seconds is because when a sudden opening occurs, the load becomes high before the plug temperature rises, and the required voltage increases. This is because when the load gradually becomes high, the increase in the plug temperature catches up with the increase in the load, so the required voltage does not become so high and the correction according to the present invention is not required. If the judgment result in step 142 is negative and the count value of RAMCd exceeds 75 and the poem is judged to be under slow acceleration, the process proceeds to step 144, and the flag ``d'' is reset in preparation for the next time. The routine exits. On the other hand, if the determination result in step 142 is positive, the process proceeds to step 146, where it is determined whether the flag rv indicating that the fully open switch is on is set. If the determination result is negative, that is, if it is determined that the throttle has not been fully opened, the routine exits directly.On the other hand, if the determination result in step 146 is positive, the process returns from the return of the fuel cut. If it is determined that the situation is a sudden acceleration in which the full-open switch is turned on within 0.3 seconds, step 1
The process advances to step 48 and the flag fd is reset. Next, the process proceeds to step 150, where a flag ``a'' is set to indicate that the correction according to the present invention is being executed.The process then proceeds to step 152, where a flag ``a'' is set to indicate that the correction according to the present invention is being executed.
Clear AMCa. Then proceed to step 154;
Initial 1i for fuel increase correction ratio F ace! ! 1.1, and then in step 156, the initial W15 degrees is also entered as the advance angle correction amount 5ace, and this routine exits. On the other hand, if the determination result in step 120 is positive and it is determined that the post-return correction according to the present invention is being executed, the process proceeds to step 160 and the RAMCa for counting the correction execution time is incremented. Then step 16
Proceeding to step 2, it is determined whether the count value of RAMCa is less than or equal to a set value, for example 500 corresponding to 2 seconds. If the determination result is positive, the fuel increase correction ratio F acc and advance angle correction l
When it is determined that it is necessary to attenuate 5acC,
Proceeding to steps 164 and 166, the fuel increase correction ratio F acc and the advance angle correction amount S acc are calculated as shown in the following equations.
After attenuating each by 11,500, this routine ends. Therefore, the fuel increase correction ratio FacC and the advance angle correction II S ace change to the reference value (Facc-1,
5acc-0), and the correction according to the present invention ends. Face-1+ 0,1x (500-Ca)/5
00-(1)Sacc-5x (500-Ca)
/ 500 ... (2) On the other hand, when the judgment result in step 162 is negative, that is, when it is judged that the attenuation of the correction has ended after 2 seconds have elapsed from the start of the correction. , proceeds to step 168, and sets the post-return correction flag f.
Reset a and exit this routine. In this embodiment, the air-fuel ratio, ignition timing, ignition advance correction amount 3acC1 fuel increase crucian carp correction ratio 1"acc, on/off state of full open switch, on/off state of idle switch, and state of fuel cut during sudden acceleration from fuel cut An example of the relationship is shown in Fig. 5. In this way, when a sudden full-throttle acceleration is performed during a fuel cut, the fuel cut-off (return) occurs at the same time as the idle switch is turned off, but then within a set time (e.g. 0.3 If the full-open switch is turned on within seconds), the correction execution condition is met. From that point on, the fuel increase correction ratio is set to an initial value of, for example, 1.1, and at the same time, the ignition advance angle correction amount is set to an initial value of, for example, 5 degrees. , then attenuate each, and end the attenuation of both at the same time.By this,
Immediately after full throttle, when the required voltage is highest, the air-fuel ratio becomes richer.
At the same time, since the ignition timing advances, the peak value of the water production voltage can be lowered. Also, by correcting both at the same time,
Knocking can be prevented by advance angle correction. In this embodiment, the ignition timing is advanced and the air-fuel ratio is enriched by first changing it to the initial value and then gradually attenuating it, so the ignition timing and air-fuel ratio are controlled. can be performed smoothly according to the engine operating condition. Note that the method of temporarily controlling the ignition timing and air-fuel ratio during sudden acceleration after a fuel cut is not limited to this; for example, it is also possible to first change it to the initial value and then return it to the original value after a certain period of darkness has elapsed. It is. In the above embodiment, the present invention was applied to an automobile engine equipped with an electronically controlled fuel injection device that senses the amount of intake air. However, the scope of application of the present invention is not limited to this, and The electron lI of the formula! It is clear that the present invention can be similarly applied to engines equipped with a 1JIa fuel injection device and general engines equipped with other air-fuel ratio control methods.

【Effect of the invention】

As explained above, according to the present invention, the secondary required voltage of the ignition system can be lowered during sudden acceleration after fuel cut. Therefore, ignition can be reliably performed even during sudden acceleration after fuel cut. Furthermore, since the ignition timing is not only advanced but also the air-fuel ratio is enriched, it has excellent effects such as preventing knocking due to a large point advance and being able to reliably lower the number*voltage.

[Brief explanation of drawings]

FIG. 1 is a flow chart showing the gist of the ignition timing and air-fuel ratio control method for an internal combustion engine according to the present invention, and FIG. 2 is a flowchart showing an automobile equipped with an intake air amount sensing type electronically controlled fuel injection device to which the present invention is adopted. FIG. 1 is a cross-sectional view showing the overall configuration of an embodiment of an engine for use with the engine, including a partial block diagram. FIG. 3 is a block diagram showing the configuration of the electronic control unit used in the embodiment, FIG. 4 is a flowchart showing a routine for controlling the ignition timing and air-fuel ratio, and FIG. are the air-fuel ratio, ignition timing, ignition advance correction amount, fuel increase correction ratio, and on/off state of the full open switch during sudden acceleration after fuel cut in the above embodiment;
FIG. 3 is a diagram illustrating an example of the relationship between the on/off state of an idle switch and the state of fuel cut. DESCRIPTION OF SYMBOLS 10... Engine, 12... Air flow meter, 14... Throttle valve, 16... Throttle opening sensor, 22... Injector, 32... Spark plug, 34... Distributor, 36. ...Rotation angle sensor, 38...Igniter, 40...Ignition coil, 42...Electronic control unit (ECU>, r cut
...Fuel cut flag, Ne...Engine rotation speed, NO...Fuel cut rotation speed, Nr...Fuel cut return rotation speed, rd...Flag while counting from return to full open, "a...・
Flag during correction after return, cd...RAM for counting between return and full open. rvbu...Full open switch on flag, Ca...RAM for counting correction execution time. F acc...Fuel increase correction ratio, 3 ace...Advance angle correction amount.

Claims (2)

[Claims] (1) In a method for controlling the ignition timing and air-fuel ratio of an internal combustion engine in which a fuel cut is performed when a predetermined fuel cut condition is met, a procedure for determining whether or not there is a sudden acceleration state after a fuel cut is provided. An ignition method for an internal combustion engine, comprising: temporarily advancing the ignition timing and enriching the air-fuel ratio to lower the secondary required voltage of the ignition system during sudden acceleration after a fuel cut. Timing and air-fuel ratio control method. (2) The internal combustion engine according to claim 1, wherein both the advance of the ignition timing and the enrichment of the air-fuel ratio are performed by first changing the ignition timing to an initial value and then gradually attenuating it. Ignition timing and air-fuel ratio control method.