JPH0660603B2 - Air-fuel ratio controller for internal combustion engine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-fuel ratio control device for an internal combustion engine used in an automobile or the like, and more particularly to an internal combustion engine capable of supplying an optimum fuel amount even when reaccelerated during acceleration correction. The present invention relates to the air-fuel ratio control device.

[Conventional technology]

2. Description of the Related Art Conventionally, in internal combustion engines used in automobiles and the like, various types of air-fuel ratio control devices that control the air-fuel ratio of an air-fuel mixture supplied to an engine combustion chamber have been used in order to reduce fuel consumption or prevent exhaust gas. For example, as disclosed in JP-A-59-196946, a carburetor and a fuel control solenoid are provided, and during normal operation after the internal combustion engine is warmed up, an oxygen sensor (O ₂ sensor) is used to feedback control the oxygen concentration in the exhaust gas. A so-called feedback carburetor system is known, which converges to the theoretical air-fuel ratio and controls the air-fuel ratio of the air-fuel mixture to a predetermined set value by open loop control at low temperatures, that is, during warm-up, starting, high load, and deceleration. There is.

Further, as disclosed in, for example, Japanese Patent Laid-Open No. 60-62630, a second solenoid valve for controlling the air-fuel ratio during acceleration or warm-up operation is provided separately from the solenoid valve for feedback control, and the throttle opening degree is provided. There is known an air-fuel ratio control device that performs acceleration correction by an amount corresponding to the throttle opening change rate when the change rate is equal to or higher than a predetermined value and after the change rate is equal to or lower than the predetermined value, for a duration corresponding to the throttle opening change rate. There is.

[Problems to be solved by the invention]

In these feedback carburetor systems,
The air-fuel ratio during acceleration is corrected by the amount of fuel injected from the acceleration pump incorporated in the carburetor to improve driving performance.

However, the acceleration pump is a mechanical type and the fuel injection amount is generally determined according to the opening degree of the throttle, and when used under various operating conditions such as an automobile,
Since it is difficult to set the optimum amount of fuel to be supplied according to various acceleration conditions, it is generally necessary to configure so that a large amount of fuel is supplied from the viewpoint of driving performance, and in terms of driving performance and fuel efficiency, It was difficult to meet high requirements. Also,
The air-fuel ratio control when reaccelerated during acceleration correction was not considered.

The present invention has been made to solve the above problems, and an object of the present invention is to obtain an air-fuel ratio control device for an internal combustion engine capable of improving the operating performance during acceleration / deceleration without supplying extra fuel. To aim.

[Means for solving problems]

An air-fuel ratio control device for an internal combustion engine according to the present invention, a carburetor having a built-in acceleration pump for supplying fuel to the internal combustion engine,
Fuel supply means including at least one electromagnetic valve configured to control the air-fuel ratio by duty control, operating state detection means for detecting the operating state of the internal combustion engine, and operating state or acceleration. The acceleration control amount determining means for setting a predetermined acceleration control amount to be given to the solenoid valve and the control duty of the solenoid valve according to the operating state are given and the acceleration control amount is given for different acceleration control times according to In this case, the control amount determining means for determining the control duty of the solenoid valve based on the acceleration control amount is provided, and the acceleration control amount determining means is an acceleration determining means for detecting that the vehicle is in an accelerated operating state, and an operating state. Acceleration control time determination means for determining the optimum acceleration control time according to each operating state according to the output of the acceleration determination means, and acceleration control time for measuring the acceleration control time When a new acceleration control time is set by the measuring means and the acceleration control time determining means, the acceleration control time is compared with the remaining time value of the acceleration control by the acceleration control time measuring means to obtain long time data. The comparison means is set in the measuring means, and the acceleration control amount calculating means outputs the acceleration control amount to the control amount determining means while the acceleration control time measuring means measures the acceleration control time when acceleration is determined by the acceleration determining means. It is a waste.

[Action]

According to the present invention, when the acceleration control amount determining means detects the acceleration operation state, the control duty of the solenoid valve for fuel supply is controlled according to the predetermined acceleration control amount during the acceleration control time according to the operating conditions such as acceleration. By controlling in such a direction as to increase, the fuel amount according to the acceleration condition is supplied in addition to the fuel supply amount by the acceleration pump.

〔Example〕

An embodiment of an air-fuel ratio control device for an internal combustion engine according to the present invention will be described below with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment thereof. In FIG. 1, the fuel supply means is composed of an electromagnetic valve 1 for controlling the supplied fuel by duty control, a carburetor 11 including an acceleration pump 10, and acceleration.

The output of the operating state detecting means 2 for detecting the state of each part of the internal combustion engine is the acceleration control time determining means 7 and the control amount determining means 4 in the acceleration control amount determining means 3 for determining the fuel supply amount during acceleration.
It is designed to output to.

The acceleration control amount determining means 3 is an acceleration determining means 5 for detecting that the internal combustion engine is in an accelerating operation state, an acceleration control amount calculating means 6 for giving an acceleration control amount given to a predetermined solenoid valve 1, and an operating state detection. Acceleration control time measuring means 7 for determining the optimum acceleration control time according to each operating state according to the outputs of the means 2 and the acceleration determination means 5, and the acceleration for measuring the acceleration control time given by the acceleration control time determining means 7. The value of the control time measuring means 8 and the value of the acceleration control time determining means 7 when a new acceleration control time is set is compared with the remaining time value of the acceleration control of the acceleration control time measuring means 8 to obtain long time data. It is configured by a comparing means 9 which is selected and set in the acceleration control time measuring means 8.

The control amount determining means 4 determines the control amount of the solenoid valve 1 according to various operating states according to the signal from the operating state detecting means 2, and at the same time, the acceleration control time measuring means 8 controls the acceleration while the acceleration control time is being measured. The control duty value of the solenoid valve 1 is determined based on the acceleration control amount of the amount calculation means 6.

As described above, by supplying the fuel suitable for the operating condition from the solenoid valve 1 in addition to the fuel supplied from the accelerating acceleration pump 10 at the time of accelerating, the increased fuel amount required during the accelerating operation is optimally controlled. As a result, the operating performance can be improved without supplying extra fuel.

FIG. 2 shows a concrete example of the functional block diagram of FIG. Referring to FIG. 2, first, the structure of the engine will be described. 101 is a piston, 102 is a cylinder,
Reference numeral 103 is an intake valve, and 104 is an exhaust valve.

The exhaust gas discharged from the exhaust valve 104 is exhausted by the exhaust pipe 10.
Three-way catalytic converter 10 provided therein through 5
It passes through 6 and is exhausted into the air.

Further, a throttle valve 108 is arranged inside the intake valve 107. A venturi 109 and an air cleaner 110 are provided upstream of the throttle valve 108.

When the intake air sucked through the air cleaner 110 passes through the venturi 109, the fuel in the float chamber 111 is sucked through the main fuel passages 24, 112 to be dewed and become a mixture with the intake air to be throttled. It is supplied into the cylinder 102 via a valve 108 and an intake pipe 107.

In this case, the main air bleed 13 and the main fuel solenoid valve 14 are provided in the middle of the main fuel passage 112, and the fuel reaching the venturi 109 from the main fuel passage 112 is provided on the upstream side of the venturi 109. After being atomized by the intake air from 15, it is guided to the venturi 109.

Further, a part of the fuel amount from the float chamber 11 to the main air bleed 13 is changed by opening / closing the main fuel solenoid valve 14. The main fuel solenoid valve 14 is a normally open solenoid valve.

On the other hand, an idle port 16 is provided on the downstream side of the throttle valve 108, a slow air passage 17 is provided on the upstream side of the venturi 109, and a throttle between the idle port 16 and the slow air passage 17 is provided. A slow fuel solenoid valve 18 is provided in the fuel passage, and when the throttle valve 108 is in an almost fully closed state at idle, the slow fuel solenoid valve 18 is opened to throw the fuel in the float chamber 111. The intake air from the air passage 17 is sucked to form a mixture, and then the mixture is ejected from the idle port 16.

The slow fuel solenoid valve 18 is a normally closed solenoid valve. Further, the amount of air-fuel mixture discharged from the idle port 16 is adjusted by the slow adjustment screw 19.

Here, the throttle valve 108 is connected to an accelerator pedal (not shown), and has an opening degree corresponding to the depression amount of the accelerator pedal during traveling.

On the other hand, the cylinder 102 is provided with a jet valve 20 having a small diameter in addition to the intake valve 103, and between the jet valve 20 and the upstream side of the venturi 109, the air-fuel mixture from the venturi 109 to the intake valve 103 is provided. A jet fuel passage 21 is provided in parallel with the passage, and a jet fuel solenoid valve 22 provided so as to open and close the fuel passage from the float chamber 111 opened in the middle of the jet fuel passage 21 is opened, thereby jet air intake. The fuel in the float chamber 111 is sucked by the intake air from 23 to form a high-speed air-fuel mixture, and the cylinder 10 is operated by the jet valve 20.
2 is injected into the cylinder 102 to supply a high-speed mixture to the cylinder 102 independently of the mixture from the intake pipe 107, and a swirl of the mixture is generated in the cylinder 2.

In this case, the jet fuel solenoid valve 22 is a normally open type solenoid valve.

39 is an acceleration pump. The acceleration pump 39 is interlocked with the throttle valve 108 so that fuel proportional to the amount of change of the throttle valve 108 is directly injected into the upper part of the venturi 109 by the nozzle 40.

Next, the configuration of the air-fuel ratio control system will be described. Reference numeral 30 is an oxygen sensor that detects the oxygen concentration in the exhaust gas, and 31 is a temperature sensor that detects the temperature of the cooling water 32 of the engine. The outputs of these oxygen sensor 30 and temperature sensor 31 are control circuit 3
It is designed to be input to 8.

Further, the idle switch 33 is turned on (closed) when the opening of the throttle valve 108 is almost fully closed, that is, during idle operation, and is connected to the control circuit 38.

The valve opening detector 34 is connected to the rotary shaft of the throttle valve 108, outputs a voltage signal corresponding to the opening of the throttle valve 108, and its movable terminal is also connected to the control circuit 38.

The rotation speed detector 35 for detecting the engine rotation speed N takes out a rotation pulse signal having a cycle corresponding to the engine rotation speed N from a connection point between the ignition coil 36 and the interrupter 37.
This rotation pulse signal is also sent to the control circuit 38.

Based on the detection output signals of the oxygen sensor 30 to the rotation speed detector 35, the control circuit 38 sets the air-fuel ratio in all operating states after the engine is started to the main fuel solenoid valve 14, the slow fuel solenoid valve 18, and the jet fuel solenoid. The control circuit controls the stoichiometric air-fuel ratio or a set value by changing the open / closed state of the valve 22.

In this case, the slow fuel solenoid valve 18 is controlled to be either on or off, while the main fuel solenoid valve 14 and the jet fuel solenoid valve 22 are controlled in their duty ratios of on time and off time.

As shown in FIG. 3, the control circuit 38 includes an arithmetic processing unit (hereinafter abbreviated as CPU) 380 and a read-on memory (hereinafter abbreviated as ROM) 381 that stores programs and constants for performing air-fuel ratio control. And a random access memory (hereinafter, abbreviated as RAM) that stores results during calculation
382 and an interface circuit for transmitting and receiving a signal between the oxygen sensor 30 and the like, the main fuel solenoid valve 14 and the like (hereinafter,
IFC 383).

Next, the operation related to the above configuration will be described with reference to the flowcharts shown in FIG. 4, FIG. 5, and FIG. 10 to FIG.

First, when the engine is started, the CPU 380 causes the ROM 38
The main routine shown in FIG. 4 is executed according to the program stored in 1. That is, the CPU 38
In step 1000, the current engine speed N is detected by taking in the output signal from the speed detector 35 and measuring the period of this output signal.

Next, at step 1001, the output signal of the valve opening detector 34 is fetched and the opening θ of the throttle valve 108 is detected.

In this case, since the output signal of the valve opening detector 34 is an analog voltage signal corresponding to the valve opening, it is converted into a digital signal in the IFC 383 and then taken into the CPU 380.

Next, in step 1002, the CPU 380 takes in the output signal of the oxygen sensor 30 and detects the oxygen concentration in the exhaust gas in the current operating state.

In this case, the output signal of the oxygen sensor 30 is converted into a high level signal or a low level signal by being compared with the reference voltage in the IFC 383, and then taken into the CPU 380.

Thereafter, the CPU 380 takes in the output signal of the temperature sensor 31 in step 1003 and detects the current cooling water temperature TP.

In this case, the output signal of the temperature sensor 31 is converted into a digital signal by the IFC 383, and then the CPU 380
Is taken into.

In this way, the CPU 380 uses the output signals of various sensors to determine the engine speed N, the throttle valve opening θ, and the oxygen concentration P.
After detecting the PM and the cooling water temperature TP, in the next steps 1004 to 1009, whether the operation mode of the engine is the start mode or the power mode during high load running based on the engine speed N and the throttle valve opening θ. Detects the operating state such as whether there is or is the accelerated operating state.

The operation modes in this embodiment include an inactive mode before warm-up in which the function of the oxygen sensor 30 is not normally exerted, a warm-up mode in which the cooling water temperature has not yet risen sufficiently, and a low load after completion of warm-up. Steady-state mode during constant speed rotation, start mode in which engine speed N is 400 RPM or less, power mode during high load running, engine speed N is 2000 RPM or more, and accelerator pedal is released It is distinguished from the deceleration mode (that is, the state where the idle switch 33 is on), and further, in the acceleration mode, in the power mode, and in the warm-up mode and the inactive mode, the acceleration increase duty corresponding to the acceleration is set in each mode. The fuel amount during acceleration is increased by subtracting from the set control duty of the main fuel solenoid valve 14.

The inactive mode, the warm-up mode and the steady mode are further classified into 16 types of zones Z1 to Z16 according to the engine speed N and the throttle valve opening θ as shown in FIG.

Therefore, in step 1004, the CPU 380 first detects which zone the current operating state corresponds to.

That is, as shown in detail in the flow chart of FIG. 5, first, in steps 200 to 203, four reference values θ _{1 to} θ _{4 of} the throttle valve opening degrees (corresponding to θ ₁ > θ ₂ > θ ₃ > θ
₄ ) is compared with the current throttle valve opening θ, θ> θ ₁
If so, in step 204, a power zone code indicating the power zone is set in the operating state identification register provided in the RAM 382.

If θ ₂ <θ <θ ₁ , in step 205, one zone code selected according to the engine speed N is set from the zone codes indicating the zones Z4 to Z16, and further θ ₃ < If θ <θ ₂ , in step 206, one zone code selected according to the engine speed N is set from the zone codes indicating the zones Z3 to Z15.

Further, if θ ₄ <θ <θ ₃ , in step 207, one zone code selected according to the engine speed N is further selected from the zone codes indicating the zones Z2 to Z14, and further set. If θ <θ ₄ , in step 208, one zone code selected according to the engine speed N is further selected and set from the zone codes indicating the zones Z1 to Z9.

In the processing of steps 205 to 208, as shown in the figure as a representative of the processing of step 208, four reference values N ₁ (= 400) of the engine speed determined for zone division are set.
_{RPM), N 2 (= 1000RPM} ), N 3 (= 2000R
PM) and N ₄ (= 4000 RPM), N _{2 to} N ₄ and the current engine speed N are compared in steps 2080 to 2082, and the zone code Z is obtained according to the comparison result.
1, Z5, Z9, and Z13 are steps 2083 to 20.
At 86, it is selected and set in the operating state identification register.

After detecting the operating zone in this manner, the CPU 380 detects in step 1005 to 1009 whether the operating state corresponds to the start mode to the steady mode, and controls the air-fuel ratio by the open loop based on the detection result. Or to control by a feedback loop.

That is, in step 1005, the engine speed N is compared with the reference value N ₁ (= 400 RPM), and if N <N ₁ , it is detected that the engine is in the starting mode.

In step 1006, the engine speed N and the reference value N ₃
(= 200 RPM), and if N ₃ > N and the idle switch is in the ON state, it is detected that the deceleration mode is set. Further, in step 1007, the operating state identification register is detected. It is determined whether or not the power zone code has been set in, and if it is set, the power mode is detected.

Further, in step 1008, the current detected water temperature TP
Is compared with the reference value TPo, and if TP <TPo, it is detected that the engine is in the warm-up mode.

In step 1009, the output voltage signal V ₀₂ of the oxygen sensor 30 is compared with the reference value V, and if the state of V ₀₂ <V continues for a predetermined time (for example, 10 seconds), the oxygen sensor 30 is in the inactive mode. Is detected. Then, the open loop control process of step 1011 is selected in the start mode, power mode, deceleration mode, warm-up mode, and inactive mode, and the feedback control process of step 1010 is selected in other modes, that is, in the steady mode.

That is, the CPU 380 is an operation mode in which feedback control based on the output of the oxygen sensor 30 is not possible (starting mode, warm-up mode, inactive mode) and operation in which feedback control is not required to give priority to horsepower over the theoretical air-fuel ratio. The open loop control process of step 1011 is selected for all the special operation modes such as the mode (power mode) and the operation mode (deceleration mode) that is meaningless even if the feedback control is executed.

On the other hand, at step 1014, the rate of change of the throttle valve 108 is detected from the rate of change of the throttle sensor 34 at predetermined time intervals, and the control duty and the acceleration increase time timer (acceleration increase time timer ( (TMACC) is set.

In step 1013, the acceleration fuel increase control is stopped in the start mode and the deceleration mode.

In step 1015, for the main fuel solenoid valve 14,
From the control duty determined before this step, the acceleration increase duty value Da% set in step 1014
And a control duty that increases the fuel supply amount during acceleration is given.

Next, in step 1012, the main fuel solenoid valve 1
4, Slow fuel solenoid valve 18 and Jet fuel solenoid valve 2
2 drive control is performed.

In an operation mode in which the operation state is not in the above conditions, that is, in a low load after completion of warm-up operation or in a steady mode during constant speed rotation, the feedback control process of step 1010 is selected and the output signal of the oxygen sensor 30 is selected. Proportional and integral processing is performed to determine the ratio (pulse duty) of the on time (closing time) and the off time of the jet fuel solenoid valve 22.
At 1012, based on the processing result of step 1010,
The jet fuel solenoid valve 22 is driven to perform proportional integration processing (PI
Control) to converge the air-fuel ratio of the air-fuel mixture supplied to the cylinder 102 to the stoichiometric air-fuel ratio.

That is, the output voltage signal V ₀₂ of the oxygen sensor 30 has a high voltage level when the air-fuel ratio is on the rich side and has a low voltage level when the air-fuel ratio is on the lean side, as shown in FIG.
Set the voltage corresponding to the stoichiometric air-fuel ratio (= 14.7) to the reference voltage V _TH, the output voltage signal V ₀₂ of the oxygen sensor 30 performs rich-lean judgment each time crossing the reference voltage V _TH, the determination signal As shown in the time chart of FIG. 8, the proportional-integral processing is performed to determine the control amount, and the duty ratio D _J of the pulse signal having a constant cycle for driving the jet fuel electromagnetic valve 22 is controlled correspondingly. Since steps 1015 and 1012 have already been described, the description thereof will be omitted here.

As is apparent from the above, the air-fuel ratio of the air-fuel mixture supplied into the cylinder 102 is controlled to the lean side in proportion to the increase in the on-time duty of the jet fuel solenoid valve 22, as shown in FIG. Conversely, the on-time duty is controlled to the rich side in proportion to the shortening of the on-time duty.

As a result of continuing such feedback control, the air-fuel ratio of the air-fuel mixture supplied into the cylinder 102 converges to the stoichiometric air-fuel ratio.

In this case, during the feedback control, the main fuel solenoid valve 14 is driven to the fully closed state with the duty ratio of its drive pulse set to 100% as shown in Table 1 below, while the slow fuel solenoid valve 18 is driven. Is driven to the fully open state with its drive pulse set to the ON side.

Therefore, in the cylinder 102, the air-fuel mixture that has passed through the jet valve 20, the air-fuel mixture that has been atomized by the venturi 109 through the bypass passage 24 of the main fuel electromagnetic valve 14 and that has passed through the intake valve 103, and the idle port The air-fuel mixture from 16 will be supplied.

In the steady running state, during feedback control,
The air-fuel ratio of the air-fuel mixture from these three passages is controlled to the stoichiometric air-fuel ratio by changing the air-fuel ratio of the air-fuel mixture from only the jet valve 20.

In this case, the proportional constants P _R and P _L on the rich side and the lean side and the integration constants I _R and I _L on the rich side and the lean side in P1 control are determined for each operating zone as shown in Table 2 below. Fine control is performed.

However, when accelerating, step 1 of the flowchart in FIG.
At 015, fuel corresponding to the acceleration increase duty (Dα%) is temporarily supplied from the main fuel solenoid valve 14, the acceleration pump 39 is corrected, and the operating performance is improved, so that the fuel is temporarily richer than the theoretical air-fuel ratio. However, after completion of the acceleration increase time, PI control is performed again to feedback control to the stoichiometric air-fuel ratio.

Now, the CPU 380 controls the solenoid valves 14, 18, 2 at the duty ratios shown in the following Tables 3 to 6 for each operation mode in the open loop control process of step 1011 in FIG.
Control 2

That is, the CPU 380 causes only the slow fuel solenoid valve 18 to be fully opened in the starting mode to rotate the engine by the air-fuel mixture only in the idle port 16, but in the power mode, the main fuel solenoid valve 1 according to the engine speed N.
4 and the jet fuel solenoid valve 22 have a duty ratio of the fourth
The air-fuel ratio of the air-fuel mixture supplied into the cylinder 10 is controlled by setting as shown in the table.

In the deceleration mode, all three solenoid valves 14, 18, 22 are fully opened to shut off the fuel.

Further, in the warm-up mode, the CPU 380 sets the duty ratio of the main fuel solenoid valve 14 and the jet fuel solenoid valve 22 for each operation zone as shown in Table 5, and the air-fuel ratio of the air-fuel mixture supplied into the cylinder 102. To control.

Further, in the inactive mode, the main fuel solenoid valve 14
The duty ratio of the jet fuel solenoid valve 22 is set to 100% and the jet fuel electromagnetic valve 22 is set to the duty ratio of each operation zone as shown in Table 6, and the air-fuel ratio of the air-fuel mixture is controlled.

In the steady mode, the warm-up mode, and the inactive mode, the main fuel solenoid valve 14 for each operation zone determined according to the engine speed N and the throttle valve opening θ in this manner.
Also, by setting the duty ratio of the jet fuel solenoid valve 22, the air-fuel ratio can be finely controlled according to the steady running state.

Next, regarding the control during the acceleration operation, steps 1013, 1014, 10 related to the acceleration operation in the flowchart of FIG.
Details of 15 will be described in detail with reference to FIGS. 10 to 14. Details of step 1014 will be described with reference to FIG.

In FIG. 10, in step 401, the valve opening change rate is detected from the difference between the output signals of the valve opening detector 34 at regular intervals of 80 msec, for example, and is stored in the acceleration register Δθ.

In step 402, when the valve opening change rate is equal to or higher than the predetermined change rate Kθ ₁ , the process proceeds to step 403.
In this step 403, from the output signal of the temperature sensor 31, when the cooling water temperature is lower than the predetermined value Kθ ₁ , that is, during warm-up, the acceleration increase time DTACC1 is set in the acceleration increase time register RTMACC.

On the other hand, when the cooling water temperature is higher than the predetermined value Kθ ₁ in step 403, the acceleration increase time DTACC2 for high temperature shorter than the low temperature acceleration increase time DTACC1 is set in the acceleration increase time register RTMACC, and the process proceeds to step 406. .

In step 406, the predetermined acceleration increase duty KD1 is set to the acceleration increase duty storage register RA.
Store in CC.

Next, in steps 407 and 408, step 40
After the acceleration operation state is detected in step 2, the new acceleration increase time data set in step 404 or step 405 and the acceleration increase measurement timer T for measuring the acceleration increase remaining time
The timer that stores a large value by comparing with MACC or the inside of the register is the acceleration increase time measurement timer TMACC
Works to stay in.

On the other hand, when the predetermined valve opening change rate Kθ ₁ or less is detected in step 402, it is considered that the steady operation state is restored, and the process proceeds to step 409, where the remaining time of the acceleration increase time timer TMACC is “0”. If not, the process proceeds to step 410, the acceleration increase time timer TMACC is decremented every time a certain time has elapsed, and the process ends again at step 409 when the remaining time of the acceleration increase time timer TMACC is not "0", the step At 410, it operates so as to subtract if a certain period of time has passed, and then step 4
If the acceleration increase time timer TMACC is "0" at 09, the routine proceeds to step 411, where the contents of the acceleration increase duty storage register RACC are cleared.

Details of step 1013 in FIG. 4 are shown in FIG. In the start mode and the deceleration mode, since it is not necessary to increase the acceleration, the acceleration increase duty storage register RACC and the acceleration increase time measurement timer TMACC are set to steps 501 and 502.
Clear with.

In step 1015 of FIG. 4, as shown in FIG.
Only when the acceleration increase time measurement timer measurement TMACC is not "0", the routine proceeds from step 603 to 604, and from the basic control duty DMB of the main fuel solenoid valve 14 set in steps 1010 and 1011 of FIG. 4 to step 101.
Acceleration amount increase duty storage register RACC determined in 4
Is subtracted and the amount of fuel corresponding to the acceleration increase duty Dα% is increased for a time period corresponding to the operating state.

Here, the reason why the processes of steps 407 and 408 in FIG. 10 are necessary will be described. When the acceleration increase time is determined in steps 404 and 405 without the processing of steps 407 and 408, the acceleration increase time DTACC1 or DTA
When CC2 is directly written, the trouble shown in FIG. 13 may occur.

That is, in FIG. 13, the acceleration control condition is satisfied at time t ₀ , and the acceleration increase time D set in step 404 of FIG. 10 is set.
After setting TACC1, acceleration increase time measurement timer TMA
After CC begins to measure the time DTACC1, after a new acceleration condition is satisfied acceleration increase time in step 405 DTACC2 is set to acceleration increase time measuring timer TMACC at time _{t 1,} at step 409, 410 and 411 At time t ₂ after measuring the acceleration increase time, the acceleration increase time DT
After ACC2 has elapsed, the acceleration increase duty storage register R
Since the contents of the ACC is cleared, results in the increase control in a short time when it should be acceleration increase to the original time t ₃ is interrupted, the operating performance problems occur to deteriorate.

When an acceleration condition occurs at the timing described with reference to FIG. 13 by adding the measures shown in steps 407 and 408, the acceleration duty is given as shown in FIG. 14, and the deterioration of driving performance is prevented. As described above, during acceleration operation, it is possible to give the main fuel solenoid valve an acceleration increase duty during the acceleration increase time corresponding to the acceleration operation, so the basic injection amount of the acceleration pump 39 should be set to a small amount. By supplying the required fuel amount according to the acceleration operation condition from the main fuel solenoid valve 14, it becomes possible to control the injection time, which cannot be realized by the acceleration pump, so that the operation performance during acceleration can be improved. Also,
When a new acceleration is detected during the acceleration correction, the one with the longer remaining time of the acceleration correction is validated, so that the optimum acceleration correction can be realized regardless of the acceleration state.

Although the example in which the main fuel solenoid valve 14 is not used for the feedback control in the steady mode has been described above, the present invention is applied to this solenoid valve even when the air-fuel ratio control is performed by only one solenoid valve used for the feedback control. It goes without saying that you can do it.

Further, in the above embodiment, the example in which the increase duty is separately calculated during acceleration and corrected to the basic control duty value is shown, but the acceleration operation may be set as one open loop condition.

〔The invention's effect〕

As described above, according to the present invention, during acceleration operation, a predetermined acceleration control amount fuel control solenoid valve is provided for an acceleration increase time corresponding to acceleration, so that re-acceleration during acceleration correction is encountered. In addition, it is possible to obtain an inexpensive air-fuel ratio control device for an internal combustion engine that satisfies the driving performance while minimizing the fuel supply by accelerating the fuel injection amount by the acceleration pump incorporated in the carburetor to be small. .

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of an air-fuel ratio control device for an internal combustion engine of the present invention, and FIG. 2 is a diagram showing a configuration of a specific embodiment of the air-fuel ratio control device for an internal combustion engine of the same. 2 is a block diagram showing the configuration of a control circuit in the air-fuel ratio control system for an internal combustion engine of FIG. 2, FIGS. 4 and 5 are flow charts for explaining the operation of the control circuit of the same as above, and FIG. 6 is an embodiment of the same as above. FIG. 7 is a diagram showing the relationship between the engine speed and the deceleration mode corresponding to the throttle valve opening, FIG. 7 is a diagram showing the relationship between the air-fuel ratio and the output voltage of the oxygen sensor in the same embodiment, and FIG. 8 is the same embodiment. FIG. 9 is a time chart showing the rich / lean discriminant relationship between the output voltage of the oxygen sensor and the voltage corresponding to the theoretical air-fuel ratio in FIG. 9, and FIG. 9 is a view showing the relationship between the on-time duty of the jet fuel solenoid valve and the air-fuel ratio in the same embodiment as above. , First 0 Figure to Figure 12 is a flowchart showing details of a portion of the flow chart of FIG. 4, 13
FIG. 14 and FIG. 14 are views for explaining the details of the flowchart of FIG. 1 ... Electromagnetic valve, 2 ... Operating state detecting means, 3 ... Acceleration control amount determining means, 4 ... Control amount determining means, 5 ... Acceleration determining means, 6 ... Acceleration control amount calculating means, 7 ... Acceleration control time determination means, 8 ... acceleration control time measurement means, 9 ... comparison means, 10 ... acceleration pump, 11 ... carburetor, 12 ...
... fuel supply means. The same reference numerals in the drawings indicate the same or corresponding parts.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Masaaki Miyazaki Inventor Masaaki Miyazaki 840 Chiyoda-cho, Himeji City, Hyogo Prefecture Mitsubishi Electric Corporation Himeji Plant (56) Reference JP-A-60-62630 (JP, A) JP-A-58- 140454 (JP, A) JP 60-95172 (JP, A) JP 62-191651 (JP, A)

Claims (1)

[Claims] 1. A fuel supply means including a carburetor having a built-in acceleration pump for supplying fuel to an internal combustion engine, and at least one solenoid valve configured to control an air-fuel ratio by duty control. An operating state detecting means for detecting an operating state of the internal combustion engine; and an acceleration control amount determination for setting a predetermined acceleration control amount to be given to the solenoid valve during different acceleration control times according to the operating state or acceleration. A control amount determining unit that determines the control duty of the solenoid valve according to the operating state, and determines the control duty of the solenoid valve based on the acceleration control amount when the acceleration control amount is given; The acceleration control amount determining means, an acceleration determining means for detecting that it is in an accelerated operating state, and the operating state and the output of the acceleration determining means Therefore, a new acceleration control time is set by the acceleration control time determining means for determining the optimum acceleration control time according to each operating state, the acceleration control time measuring means for measuring the acceleration control time, and the acceleration control time determining means. Then, the acceleration control time is compared with the remaining time value of the acceleration control by the acceleration control time measuring means to set long time data in the acceleration control time measuring means, and the acceleration determining means accelerates the acceleration. When the determination is made, the acceleration control time measuring means outputs an acceleration control amount to the control amount determining means during measurement of the acceleration control time, and an air-fuel ratio control device for an internal combustion engine. .