JPS5870037A - Air-fuel ratio controlling device - Google Patents

Abstract

PURPOSE:To attempt to reduce the exhaust quantity of noxious components of exhaust gas at the time of low temperature of an exhaust system by constituting to start the air-fuel ratio feedback control based on an output of an exhaust sensor at a point in time where the temperature of engine cooling water reaches a predetermined temperature. CONSTITUTION:Detected values of a suction air quantity sensor 7, O2 sensor 8, water temperature sensor 9, suction air temperature sensor 10, ignition primary signal 13, throttle opening degree sensor 15, and the like, are supplied in a control circuit 14, and by controlling the valve opening timing of a fuel injecting valve, the air-fuel ratio of a sucked gaseous mixture is controlled. In a case where an air-fuel ratio control program is started at a step 100, when the water temperature THW exceeds a predetermined temperature T1 at a step 102 and further a counter value C is set at 1 at a step 112, and then a feedback control value F is computed at a step 114 to start the feedback control.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for an internal combustion engine, and more specifically to an air-fuel ratio control device using a closed loop control method.

This type of air-fuel ratio control device uses a three-way catalyst that efficiently purifies the three components of HC%CO and NOX in the air-fuel ratio region near the stoichiometric air-fuel ratio (λ-1), which increases the concentration of residual oxygen in the exhaust gas. Feedback control is performed so that the supplied air-fuel ratio is close to the theoretical air-fuel ratio based on the detection output of the sensor.

In conventional air-fuel ratio control devices, the start timing of air-fuel ratio feedback control is controlled based on the engine cooling water temperature, but in the early stages of engine startup, even if the engine cooling water temperature rises, the O-sensor, three-way catalyst, etc. Since the temperature of the exhaust system has not risen sufficiently, the exhaust gas will not be purified even if the above feedback control is started, and the air-fuel ratio will fluctuate due to insufficient air-fuel ratio control, causing harmful components in the exhaust gas to It will be discharged in many ways. Especially for engines with a tarp charger. This tendency is strong in engines where the sensor element temperature rises slowly.

SUMMARY OF THE INVENTION In view of the drawbacks of the conventional device, an object of the present invention is to provide an air-fuel ratio control device that reduces the emission of harmful components in exhaust gas when the temperature of the exhaust system has not risen sufficiently. It's about doing.

The feature of the present invention is to take in the detection output of each sensor that detects the operating state of the engine, and calculate the remaining 'e' in the exhaust gas. i In an air-fuel ratio control device that feedback-controls the air-fuel ratio supplied in each cylinder to near the stoichiometric air-fuel ratio based on oxygen concentration, the feedback control is started after a predetermined time has elapsed from the time when the engine cooling water temperature reaches a predetermined temperature. It is composed of pressure points.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4. Figure 1 shows the overall configuration of the engine system, where l is the engine! D, 2Fi air cleaner, 3 is the throttle chamber, 4 is the intake manifold that sends air to each cylinder, 6 is the exhaust gas in each cylinder! The exhaust manifold introduced into r17, 16 is a three-way catalyst. By operating an accelerator pedal (not shown), the opening degree of the throttle valve 5 provided in the throttle chamber 3 is controlled, thereby controlling the engine l from the share cleaner 2.
The amount of air supplied to each cylinder is controlled. The throttle valve 5 is provided with a throttle sensor 15 that detects whether the throttle valve 5 is fully closed, that is, whether the engine is in an idling state, and the detection output of the throttle sensor 15 is controlled. The signal is input to the circuit 14. Here, the throttle sensor 15 is the throttle valve 5.
is in the ON state when it is in the fully closed state.

The amount of air controlled by opening and closing the throttle valve 5 is measured by an air flow meter 7 provided upstream of the throttle valve 5 in the throttle chamber 3, and its detection signal is input to the control circuit 14.

Near the outlet of the IK exhaust manifold 6, a sensor 8 is provided to detect the concentration of residual oxygen in the exhaust gas. The sensor detection signal is calculated and a control signal is outputted to inject fuel at a predetermined timing for a predetermined period of time to an injector 20 provided near the inlet of each cylinder of the engine I. Also, 12 is Disrido Computer 11
Ignition provided in each cylinder via! This is an ignition circuit that sends an ignition signal to the lug, and an ignition coil-transmission signal 13 is input from the ignition circuit 12 to a control circuit 14.

This ignition coil number is processed as an engine rotation speed signal by the control circuit 14, and is used as basic information for engine control of each stock, including air-fuel ratio control.

Furthermore, a water temperature sensor for detecting cooling water temperature, 10
is an intake temperature sensor that detects the temperature of intake air.

The present invention is configured to determine the start timing of air-fuel ratio feedback control based on the detection output of the water temperature sensor 9.

Note that the fuel supply system is not the main point of the present invention, so a description thereof will be omitted.

,next#! 2 shows the specific configuration of the control circuit 14), which is a 30Fi frequency divider circuit, which inputs the 30Fi ignition-next signal 13 and divides the control circuit 14 at a predetermined frequency division ratio. The pulse signal is output to the basic injection amount calculation circuit 40.

In the basic injection amount calculation circuit 40, the basic injection pulse Tp is based on the air amount detection signal from the air flow meter 7 at the timing of the frequency division circuit 30L:r3.
is output to the injection amount correction circuit 50 via the diode 25, and the interrupt control section 5 in the microcomputer 30
Output to 2. In the injection amount correction circuit 50, the water temperature sensor 9,
The detection output of the intake air temperature C/S1O and the air-fuel ratio correction signal 29 outputted from the microcomputer 60 are taken in, and the basic injection/lSSP/lump width is changed based on these signals, and the injector drive NO.4 is changed. The pulse Tt is output to the base of the output transistor 24 via the t agate 23.

A current adjustment resistor 22 and a parallel circuit of a solenoid 20A that controls the injection valve of the injector 20 provided in each cylinder are connected in series between the collector of the output transistor 24 and the battery vB'. Each time the injector driving pulse T1 is applied to the output transistor 24, an exciting current flows through the solenoid 20m of each injector 20, and as a result, the valve opening time of the injector 20 (pulse T
In other words, the fuel injection lid is controlled. Further, the injection amount correction circuit 50 is configured to receive a basic injection pulse cut signal 27, and fuel cut is performed based on this signal 27. Furthermore, the or f-
) 23 is an injection amount increase t4 rus 2 for increasing the fuel injection amount asynchronously with the injector drive/arm rus T1.
8 is input under specific operating conditions of the Ennon (for example, during acceleration, idling, etc.).

The basic injection pulse cut signal 27 and the injection amount increase pulse 28 are both outputted from the digital output port 56 in the 1-microcomputer 60.

Next, we will explain the configuration of the microcontroller 0. 642 is a central processing unit (OPU) that performs digital calculation processing related to air-fuel ratio control.
44 is a readable and writable memory element (RAM)
and a storage element (R
OM). Here, the RAM 44 is provided with a soft counter, and the time measured up to the start of the air-fuel ratio feedback control 41 is measured by the soft counter.
A timer 8 measures the activation cycle of the interrupt processing program. 52 accepts various interrupts, outputs an interrupt signal to the CPU 42 via the balance 70, receives the basic injection/Yars Tp, and monitors the rising and falling points of the basic injection pulse. It is an integrated control section. 54 is a digital input port that receives the detection output of each yuzu sensor that outputs a digital signal. Detection outputs from a throttle sensor 15 that detects the opening/closing state, a starter switch 18 that detects the starting state of the engine, a clutch switch 19 that detects the depressed state of the clutch, and a shift switch 33 that detects the switching state of the transmission are input. In actual proportion, clutch switch 19
The MA/D converter 56 is configured to determine the temperature when the vehicle starts based on the detection output of the shift switch 33, and the MA/D converter 56 has an air flow meter 7 that outputs an analog signal and a water temperature. The detection output of the sensor 9 is captured and converted into a digital signal. 5
``'-8 is a digital output port that outputs a digital control signal, and as described above, the basic injection t4 rus 27 and the injection amount increase 11 rus 2 are output from the digital output port 58.
8 is output. Further, 62 is a D/A converter that outputs an analog control signal (F), and the above-mentioned air-fuel ratio correction signal 29 is output from the KD/mucompartaro 2.

In this way, the input/output interface 80 composed of the digital input port 54, the digital output port 58, the A/D converter 56, and the D/Muko/Partaro 2 takes in the detection output of each Hinoki sensor and transfers it to the pass line 70.
is sent to the 0PU42 via the CPU42, and the R
After arithmetic processing is performed based on the control program stored in the OM 45, the control signal is output from the digital output port 58 and the D/A converter 62 to the outside.

Next, FIG. 3 shows the processing contents of the air-fuel ratio control device according to the present invention. In the figure, when the air-fuel ratio control program is started in step 100, it is determined in step 102 whether the engine cooling water temperature THW is THW≧T1 ('rl is the set temperature), and in step 102, it is determined No. If it is determined, the process moves to step 104. Here, the set temperature T1 is the temperature at which the warm-up operation of the engine is approximately completed,
For example, it is 50°C. Then, in step 104, the RAM
Data 0 is set in the soft counter stored in 44. This data C is used to set the time required for the temperature of the exhaust system to rise sufficiently after the engine coolant temperature THW reaches the set temperature T1. Then, in step 106, the air-fuel ratio control coefficient F' is set to 1, and the process moves to step 116.

On the other hand, in step 102, the engine cooling water temperature TI (W is T1
When it is determined that THW≧T1, that is, when it is determined that the engine cooling water temperature has reached T1, the content C of the L soft counter is decremented by 11, and in the next step 110, the content of the soft counter is set to 0. It is determined whether or not ' is present at C50.

If Stella f110 determines that 0≦0 is not true, that is, if it is determined that a predetermined period of time has not elapsed since the engine cooling water temperature reached the set temperature T1, the process moves to step 106, and the process is similar to that described above. processing is performed. On the other hand, if it is determined in the step 110 that the content O of the soft counter is C60, that is, the engine cooling water temperature THW has reached the set temperature T1 and the predetermined time for pressure relief has elapsed, the next step 112 is performed.
I can do it. Further, other routines are executed at Stellar f116°, and execution of the air-fuel ratio control program ends at Stellar f118.

Figure 4 shows the Ot sensor output waveform ((a) in the same figure), the waveform of the innoector drive current ((b) in the same figure), and the air-fuel ratio ((...) in the same figure) in the air-fuel ratio control device according to the present invention. The characteristics are shown in relation to the conventional example (A), and as is clear from the figure (in the conventional example, feedback control is started at the point when the base temperature of the senna is low (time T, ), so it is sufficient It can be seen that air-fuel ratio control is performed. - The air-fuel ratio control device according to the invention is 0. The temperature is controlled by Ogunruno until the temperature reaches the temperature required for the sensor to operate normally.
It can be seen that the change in the air-fuel ratio is small because the feedback control is started when the temperature has risen sufficiently (time T, ).

In the present invention, the air-fuel ratio feedback control is started after a predetermined period of time has elapsed from the time when the engine cooling water temperature reaches a set temperature corresponding to the temperature at the end of warm-up operation. It is possible to reduce the emission of harmful components in the exhaust gas when the exhaust gas is not sufficiently elevated.

[Brief explanation of the drawing]

The striped diagram 1 is an overall configuration diagram of the engine system, FIG. 2 is a block diagram showing the specific configuration of the control circuit 14, FIG. 3 is a flowchart showing the contents of the air-fuel ratio control program, and FIG. FIG. 2 is a characteristic diagram showing the control characteristics of the fuel ratio control device in relation to a conventional example. 1...Engine, 5...Throttle pulp, 8...0, sensor, 9...Water temperature sensor, 1
4... Control circuit, 20... Injector, 4
2...OP17, 44...RAM. 46...ROM0 Agent Tatsuyuki Unuma (#1 or i name) Figure N Figure 2 v8 No. 31]

Claims (1)

[Claims] +1) Air-fuel ratio control that takes in the detection output of each pole sensor that detects the operating state of the engine and feedback-controls the air-fuel ratio supplied to each cylinder to near the stoichiometric air-fuel ratio based on the residual sensitive concentration in the exhaust gas. An air-fuel ratio control device characterized in that the feed/single feed control is started after a predetermined period of time has passed since the engine cooling water temperature has reached a predetermined temperature.