JPS588245A - Control device of air-fuel ratio - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the fuel consumption by delaying the suction pipe negative pressure signal and providng to a circuit for deciding the executability of the feedback control. CONSTITUTION:The signals from a sensor 20 for detecting the cranking state of an engine, negative pressure switches 6, 16 fixed to the suction, exhaust pipes 2, 3 and a negative switch 18 fixed to the slow port 17 are provided while the control section 10 will control the slow and main solenoid valves 8, 10 thus to control the amount of air and the fuel supply. In the control section 10, the signal from the switches 6, 18 is provided through the delay circuits 32, 36 to AND gate 38 to drive the valves 8, 9 by means of the drive circuit 28. Consequently even when the negative pressure in the suction pipe 2 has dropped momentality in the low rotation area of the engine, the feedback control is not stopped thereby the deterioration of the fuel consumption, is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device, and more specifically, detects the residual oxygen level in company exhaust gas, and adjusts the air-fuel ratio in the carburetor to the stoichiometric air-fuel ratio based on the detected signal. The present invention relates to an air-fuel ratio control device that performs foot knock control in the vicinity.

In general, as a general feature of internal combustion engines, when the opening degree of a throttle valve linked to an accelerator pedal (hereinafter referred to as throttle opening degree) is equal, the lower the engine speed, the lower the intake pipe negative pressure. In the conventional air-fuel ratio control device using the foot kick control method, the throttle valve is close to fully open (ll
Feed/per unit control is stopped at L tracheal negative pressure (small) and the 9 fuel in the carburetor is made rich, making it easy to control feed/per unit even in low engine speed ranges. The disadvantage was that it stopped.

For example, when driving in an urban area where the driving state of a car repeats the pattern of starting → accelerating → stopping, the engine is running at a low rotation speed at the time of starting, and even though the throttle opening is not large (K), the intake pipe negative pressure easily increases. Whenever the negative pressure becomes less than the set value of the negative pressure switch that detects the negative pressure, the air-fuel ratio control device stops the feedback control. Since the air-fuel ratio in the carburetor becomes richer during the feed/multiply control stop period than during the feed/pump control, fuel efficiency deteriorates.

SUMMARY OF THE INVENTION An object of the present invention is to provide an air-fuel ratio control device that avoids stoppage of foot nosec control caused by a momentary drop in intake pipe negative pressure when starting a vehicle, and prevents deterioration of fuel efficiency.

The feature of the present invention is to detect the concentration of residual oxygen gas in exhaust gas,
In an air-fuel ratio control device that performs foot control to control the air-fuel ratio in the carburetor to near the stoichiometric air-fuel ratio based on the detection signal, the air-fuel ratio in the intake pipe is used as an input signal to a determination circuit that determines whether foot nosec control can be performed. The present invention is configured to use a negative pressure signal and to delay the intake pipe negative pressure signal by a predetermined period of time.

Embodiments of the present invention will be specifically described below based on the drawings. FIG. 1 shows the overall configuration of an air-fuel ratio control device according to the present invention. In the figure, l is a carburetor, C is an intake pipe, and 3 is an exhaust pipe.

Now, the driver who operates the accelerator pedal (not shown) controls the opening of the throttle valve J installed in the carburetor, and the air is supplied to each cylinder of the engine from the air cleaner (not shown). Amount controlled.

In addition, the engine load condition (intake pipe negative pressure) is shown in the intake pipe.
A negative pressure switch 4 is provided to detect the intake pipe negative pressure signal and a control signal outputted from a control section 10 based on the detection output of various sensors to be described later. Valve time is controlled.

On the other hand, fuel supplied from a fuel pump (not shown) is stored in a fuel chamber through a fuel pipe, passes through a main orifice, and then goes to an injection nozzle installed in a small venturi. is supplied to the vaporizer l.

Further, the fuel is supplied to the carburetor l from the injection nozzle it by passing through the main nozzle nozzle separately from the above-mentioned supply system and bypassing the main orifice lλ. Therefore,
The fuel supply from injection nozzle l# can be controlled by the opening time of the main solenoid nozzle.

On the other hand, the amount of air supplied to the carburetor/inside is the slow solenoid P)
This is corrected by controlling the opening time of the valve t, thereby controlling the amount of air flowing in from the air intake.

Further, /l is an exhaust gas sensor, and this sensor is for detecting residual oxygen in the exhaust gas to optimally control the air-fuel ratio in the carburetor l. It is a negative pressure switch provided at the slow port 77. The negative pressure switch ``it'' is for detecting whether or not the engine is in an idling state.

Next, a specific configuration of the control section 10 is shown in FIG.

In the figure, the negative pressure switch 4 outputs a logic [111 signal] when the intake pipe negative pressure becomes less than a predetermined value. Further, sensor code 0 detects whether or not the engine is in a cranking state, and a logic -01 signal is output during cranking. Furthermore, the negative pressure switch it has a logic s1g signal when the engine is not at idle condition 11, and a logic 10 signal otherwise.
・Signal is output.

Further, aO is a determination circuit that takes in the various sensors and determines whether or not the various pressure controls can be executed, and the determination circuit J- is a delay circuit J that delays the detection output of the negative pressure switch 4 for a certain period of time. It is composed of an inverter JIc that inverts the detection output of the sensor Q, a delay circuit 34 that delays the detection output of the negative pressure switch/1 for a certain period of time, and an AND circuit sr that takes the AND of these outputs. Additionally, the proportional integral signal inputs the detection output of the exhaust gas sensor (Ol sensor in this example)/4 and outputs a proportional integral signal for controlling the air-fuel ratio in the vaporizer (to) near the stoichiometric air-fuel ratio. The circuit is a pulse conversion circuit that converts the output signal of the proportional-integral circuit into a duty pulse train signal. 81. This is a drive circuit that outputs a drive signal to the through solenoid 8.

In the above configuration, normally, the proportional integral circuit J4cK outputs a proportional integral signal vr according to the operating state of the engine based on the 0-fold upper tito detection output, and a duty pulse train is generated based on the proportional integral signal as described above. The signal is sent to the main solenoid 81 via the pulse conversion circuit J4> drive circuit. The gas is output to the solenoid S. As a result, the main runoid Nonoru Buta, Sloan Renoid/Noru ft.
The opening time of the valve is controlled, and the air-fuel ratio in the carburetor I is controlled to be close to the stoichiometric air-fuel ratio.

On the other hand, if the determination circuit #O determines that the feedback control should be stopped, that is, the sensor 1. When the AND condition of 0°/l is satisfied, a control stop signal 10 is output from the determination circuit 〇 to the proportional-integral circuit KODA, and the air-fuel ratio control is stopped. In this case, in the past, the detection output of the negative pressure switch 1 that detects the intake pipe negative pressure was directly input to the AND circuit 3r without going through the delay circuits 3; If the intake pipe negative pressure drops momentarily, feedback control is easily stopped, and the air-fuel ratio shifts to the rich side, resulting in poor fuel efficiency. This situation will be explained based on FIG. FIG. 3(A) shows the turning of the automobile, and FIG. 3(B) shows the change characteristics of the negative pressure at that time. During the period when the car is running at a certain speed, 0≦t<T・, the intake pipe negative pressure shows a constant value, and at the start of acceleration (time t=+t'r・), the intake pipe negative pressure reaches the set value P・
From time T1 onwards, it becomes equal to or more than the set value P, and then settles down to a constant value.

Therefore, as in the conventional case, when there is no delay circuit JJ, the proportional integral signal VF output from the proportional integral circuit Koda is (0
), as shown by the dotted line, before time T, it changes around the level vr, drops to the open loop level vr@ at time t, increases linearly at time T, and the vehicle speed after acceleration changes. Level Vν bird corresponding to the corridor k time of stabbing T1
From then on, it changes mainly around the level VFI.

As a result, the air-fuel ratio (A/F) in the carburetor is as shown in the figure (D).
As shown by the dotted line, it changes to the rich side during the period T·kut≦T, and after time Ts it drops to near the stoichiometric air-fuel ratio (A/F=14.7).

In the present invention, the intake pipe negative pressure signal is passed through the delay circuit JJ, delayed by a predetermined time, for example, td(sg+-TI-T), and inputted to the AND circuit 71. is masked, and the proportional integral signal Vr changes according to the change in vehicle speed as shown by the solid line, and the air-fuel ratio A/FFi
Follow along! 2! The fuel ratio is controlled to be close to the fuel ratio (shown by the solid line in FIG. 6(D)).

As explained above, in the present invention, the intake pipe negative pressure signal indicating the carrot load state is used as an input signal of the determination circuit that determines whether foot nosec control can be executed, and the limb intake pipe member pressure signal is delayed for a predetermined period of time. I configured it so that
According to the present invention, it is possible to avoid stopping the foot nosec control caused by a momentary drop in the intake pipe negative pressure when starting the vehicle, and it is possible to prevent fuel consumption from deteriorating.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the overall configuration of the air-fuel ratio control device according to the present invention, Fig. 2 is a block diagram showing the configuration of the control section of the air-fuel ratio control device of Fig. 1, and Fig. 3 is a diagram showing the air-fuel ratio of the control section. FIG. 3 is an operation characteristic diagram showing a control operation in comparison with a conventional example. 4, /l...Negative pressure switch, 10-...Control unit, Koda...Proportional integral circuit %Co4...Resolution conversion circuit, Koto...! Dynamic circuit, JJ, Jt...Delay circuit, Jt...
AND circuit, 81+81... solenoid. Figure 3

Claims (1)

[Claims] (1) Theory of empty fist in the carburetor based on the exhaust gas sensor that detects the residual oxygen gas level in the exhaust gas and the detection output of the exhaust gas sensor! ! The air-fuel ratio control circuit outputs a control signal for controlling the fuel ratio near the fuel ratio, and the detection outputs of various sensors are included, and based on the AND result of these, it is determined whether shift feedback control can be executed or not, and the air-fuel ratio control is performed. An air-fuel ratio control device comprising a determination circuit that sends a determination signal to the circuit, wherein an intake pipe negative pressure signal is input to the determination circuit via a delay circuit. Device.・・・