JPH068287Y2 - Air-fuel ratio controller - Google Patents

Description

[Technical Field] The present invention relates to an air-fuel ratio control device, and more specifically, it feedback-controls an air-fuel ratio using an oxygen sensor, and learns this feedback control value to make the air-fuel ratio more precise. It relates to a device for controlling.

(Prior Art) Recently, the control of the intake air amount of an internal combustion engine such as an automobile is performed by discriminating between various operating modes corresponding to changes in the operating state. Among them, in particular, a starting mode, an idle mode and acceleration / deceleration are performed. In the mode, the combustion state in the engine changes transiently, so more precise control of the intake air amount is desired.

Such control of the intake air amount ultimately aims at stable control of the engine speed, and in the device for controlling the idle speed, the ISC provided in the bypass passage communicating the upstream side and the downstream side of the throttle valve. Valve (Idle Speed Control Val
ve: Idle control valve) performs so-called auxiliary air amount control (ISC) in which the intake air amount during idling is changed to control the idling speed. The control state is such that the area (opening) of the bypass passage is changed in an analog manner by the duty-controlled ISC valve to operate the air flow rate, and the duty value (hereinafter referred to as “duty value” so as to match the idle speed with a predetermined target value). , ISC control value) is feedback-controlled. In addition, when an auxiliary load such as an air conditioner or power steering is applied, an auxiliary air system (FICD) is used to prevent the rotation speed from dropping.
As a control, a correction duty value as a load correction statement of a fixed value determined according to the magnitude of the auxiliary machine load is added to the above-mentioned ISC control value for control. As a result, the air flow rate during idling is precisely manipulated to accurately and responsively control the idling speed.

By the way, it is necessary to control the fuel amount with good responsiveness to the load fluctuation of the internal combustion engine. From such a requirement, instead of detecting the air flow rate by a so-called air flow meter, the throttle valve opening degree has been recently used. A system (referred to as an α-N system, which will be described later in detail) for detecting the intake air amount using the engine rotation speed as a parameter has been developed to meet the above-mentioned requirements.

An example of a conventional fuel supply device for an internal combustion engine using this type of system is described in Japanese Utility Model Publication No. 60-39465. In this device, the intake air amount is detected from two detector outputs of a throttle valve opening sensor and a rotation speed sensor without using an air flow meter, and the fuel injection amount is controlled based on the intake air amount. Therefore, although there is a drawback of the air flow meter, the detection error during the transition due to the influence of the intake pulsation and the inertial force of the air flow meter is avoided, and the fuel injection amount with excellent responsiveness is obtained to improve the drivability of the engine. .

(Problems to be Solved by the Invention) However, such an air-fuel ratio control device using the conventional α-N system does not consider the influence of ON / OFF of the auxiliary air system (FICD). Therefore, there were the following problems.

(I) In a conventional device having an air flow meter, the change in the intake air amount due to ON / OFF of the auxiliary air system can be known by the air flow meter, but in the α-N system, the change amount of the air amount when ON is the control unit. It is only corrected by the value stored in advance, and component variations and the like cannot be absorbed.

(II) Further, when a solenoid (FICD solenoid) having an air amount adjusting mechanism is used in the auxiliary air system, the amount of change caused by the adjustment cannot be known without special means for detecting the flow rate change. .

(III) If an attempt is made to compensate for these deviations in the air-fuel ratio correction coefficient only by normal air-fuel ratio feedback control, there will be a delay in tracking them, or there will be a problem that the correction cannot be performed in the oxygen sensor inactive state such as when left idle. Occurs.

Among the above problems, FICD especially near idle
When it is ON (air conditioner ON, etc.), the idle operation will be performed without properly correcting the deviation of the air amount change, and the base air-fuel ratio will deviate significantly from the target air-fuel ratio, resulting in deterioration of exhaust emission characteristics and fuel consumption. Invite.

(Object of the invention) Therefore, according to the present invention, by learning the difference between the air-fuel ratio correction coefficient calculated after the auxiliary load is operated and the learning value learned while the auxiliary load is not operating, Auxiliary air system O
Regardless of N / OFF, the object is to improve the exhaust emission characteristics, fuel consumption, and drivability by making the air-fuel ratio particularly appropriate during idling.

(Means for Solving the Problem) In order to achieve the above object, the air-fuel ratio control device according to the present invention has an air-fuel ratio detecting means a for detecting the air-fuel ratio of the intake air-fuel mixture as shown in the basic conceptual diagram of FIG. Based on the outputs of the operating state detecting means b for detecting the operating state of the engine, the auxiliary load detecting means c for detecting the operating state of the auxiliary load such as the air conditioner and the power steering, and the air-fuel ratio detecting means a. Correction coefficient calculation means d for calculating a correction coefficient for feedback-correcting the air-fuel ratio to a predetermined air-fuel ratio, and when learning is permitted, the air-fuel ratio is set as a target from the value of the air-fuel ratio correction coefficient while the auxiliary load is not operating. During the operation of the first learning means e that learns the learning correction coefficient that matches the air-fuel ratio as the one corresponding to the operating state at that time and stores the learned value in the corresponding first area, and the auxiliary load is operating. After the auxiliary equipment load is activated The difference between the correction coefficient calculated in step 1 and the learning value read from the first learning means e is learned as corresponding to the driving state at that time, and the learned value is stored in the corresponding second area. 2 based on the learning means f, the air-fuel ratio correction coefficient during the non-operation of the auxiliary load, and the correction coefficient read from the first learning means e as a learning correction coefficient corresponding to the operating state, the air-fuel ratio is the target air-fuel ratio. The intake air or the fuel supply amount is controlled so that the air-fuel ratio correction coefficient and the learning correction corresponding to the operating state from the first learning means e and the second learning means f are performed during the operation of the auxiliary load. Control means g for controlling the supply amount of intake air or fuel so that the air-fuel ratio becomes the target air-fuel ratio based on the correction coefficient read as a coefficient, and supply of intake air or fuel based on a signal from the control means g. Manipulate the amount It includes operation means h for the.

(Operation) In the present invention, the correction coefficient for making the air-fuel ratio equal to the target air-fuel ratio is stored in the first learning means as the learning correction coefficient corresponding to the operating state while the auxiliary load is not operating, and the correction coefficient calculating means is stored. The air-fuel ratio is controlled based on the air-fuel ratio correction coefficient calculated by the above and the learning correction coefficient read from the first learning means corresponding to the operating state. On the other hand, during the operation of the auxiliary load, the difference between the air-fuel ratio correction coefficient calculated by the correction coefficient calculation means after the auxiliary load is operated and the learning correction coefficient read from the first learning means becomes the learning value corresponding to the operating state. Based on the air-fuel ratio correction coefficient stored in the second learning means and calculated by the correction coefficient calculating means, and the learning values read from the first and second learning means corresponding to the operating state, the air-fuel ratio is Controlled. That is, when the auxiliary load operates, the learning correction coefficient in each operating state learned by the first learning means while the auxiliary load is not operating is utilized, and the air-fuel ratio control caused by the start of the auxiliary load operation is controlled. Therefore, only the error amount of is corrected rapidly by using the learning value of the corresponding second learning means so as to improve the followability of the air-fuel ratio control. Therefore, regardless of ON / OFF of the auxiliary air system,
The accuracy of the air-fuel ratio control is improved, and especially the air-fuel ratio at the time of idling becomes appropriate, exhaust emission characteristics and fuel consumption,
The drivability is improved.

(Example) Hereinafter, the present invention will be described with reference to the drawings.

2 to 6 are views showing a first embodiment of the present invention, which is an example applied to an SPi (Single Point Injection) type engine of the present invention.

First, the configuration will be described. In Figure 2, 1 is the engine, the intake air through a throttle chamber 3 from the air cleaner 2, ON / OFF by the heater control signal S _H
After being heated by the PTC heater 4, the fuel is supplied to each cylinder from each branch of the intake manifold 5, and fuel is supplied by a single injector (operating means) 7 provided upstream of the throttle valve 6 based on the injection signal Si. Is jetted. An ignition plug 10 is attached to each cylinder, and an ignition coil 12 is attached to the ignition plug 10 via a distributor 11.
The high voltage pulse Pi from is supplied. The spark plug 10, the distributor 11 and the ignition coil 12 constitute an ignition means 13 for igniting an air-fuel mixture, and the ignition means 13 generates a high voltage pulse Pi based on an ignition signal S _IGN and discharges it. Then, the air-fuel mixture in the cylinder is ignited and explodes by the discharge of the high-pressure pulse Pi, becomes exhaust gas, and passes through the exhaust pipe 14 and the harmful components (CO, H
C, NO _x ) is cleaned by a three-way catalyst and discharged from the muffler 16. Here, the flow of intake air is controlled by the throttle valve 6 in the throttle chamber 3 which is interlocked with the accelerator pedal.
The throttle valve 6 is almost closed during idling. The air flow during idling passes through the bypass passage 20 and the AAC valve (Auxiliary Air Co
ntrol Valve (idle control valve) 21 and solenoid valve 22 with adjusting mechanism shown in FIG. 3 ensure the necessary air. The AAC valve 21 is ON / OFF driven based on an opening signal Sa from a control unit 50 described later. In FIG. 3, reference numeral 23 is a main body having communication ports 23a, 23b, 23c for communicating the upstream and the downstream of the throttle valve 6, and an orifice 24 is formed at one end of the communication port 23c. The tip 25a of the rod 25 is in contact with the orifice 24, and the other end of the rod 25 is an ON / OFF solenoid.
26 is engaged. The ON / OFF solenoid 26 moves the rod 25 to the left side in the figure based on the opening signal S _FICD ,
The amount of air passing through the communication port 23c is controlled. The adjustment mechanism 27
Is an adjusting mechanism for adjusting the amount of air passing through the communication port 23c, and 28 is a blind plug.

The main body 23, the orifice 24, the rod 25, the ON / OFF solenoid 26, the adjusting mechanism 27 and the blind plug 28 together constitute a solenoid valve 22 with an adjusting mechanism.

Referring again to FIG. 2, a swirl control valve 32 is arranged near the intake port of each cylinder, and the swirl control valve 32 is connected to the servo diaphragm 34 via a rod 33.
A predetermined control negative pressure is introduced from the solenoid valve 35. A swirl control signal SC is input to the solenoid valve 35, and the solenoid valve 35 leaks the negative pressure supplied from the intake manifold 5 to the atmosphere based on this signal, thereby introducing it into the servo diaphragm 34. Negative pressure is changed continuously. The servo diaphragm 34 responds to this control negative pressure and adjusts the opening degree of the swirl control valve 32 via the rod 33.

The opening θ _TVO of the throttle valve 6 is detected by the throttle sensor 40, and the temperature Tw of the cooling water is detected by the water temperature sensor 41. The crank angle of the engine is detected by a crank angle sensor 42 built in the distributor 11, and a cylinder discrimination signal (REF signal) and a crank angle signal (POS signal) are output. The REF signal is a pulse signal that changes once every 180 °, and its pulse width (crank angle from rising to falling) differs for each cylinder. On the other hand, the POS signal is sent at a predetermined crank angle (for example, 2
It is a pulse having a rising or falling edge at (°), and the engine speed N can be known by counting this pulse. An oxygen sensor (air-fuel ratio detection means) 43 is attached to the exhaust pipe 14, and the oxygen sensor 43 is connected to an air-fuel ratio detection circuit 44. The air-fuel ratio detection circuit 44 is an oxygen sensor.
A pump current is supplied to 43, and the oxygen concentration in the exhaust gas is detected over a wide range from rich to lean from the value of this pump current. This oxygen concentration uniquely corresponds to the air-fuel ratio and is output from the air-fuel ratio detection circuit 44 as the air-fuel ratio signal Ip.

On the other hand, the operation position of the transmission is detected by the position sensor 45, and the vehicle speed VSP is detected by the vehicle speed sensor 46. The operation of the air conditioner is detected by an air conditioner switch (auxiliary equipment load detection means) 47, and the operation of the power steering is detected by a power steering detection switch 48.

The throttle sensor 40 and the crank angle sensor 42 constitute a driving state detecting means 49, and the driving state detecting means 4
9. Outputs from the water temperature sensor 41, the oxygen sensor 43, the position sensor 45, the vehicle speed sensor 46, the air conditioner switch 47, and the power steering detection switch 48 are input to the control unit 50. The control unit 50 converts the sensor information having these analog values into a digital value, and performs combustion control (air-fuel ratio control, ignition timing control, etc.) of the engine based on the digitally converted sensor information. That is, the control unit 50 has a function as a correction coefficient calculation means, a first learning means, a second learning means and a control means, and has a CPU 51, a ROM 52, a RAM 53 and an I / O port.
It consists of 54. The CPU 51 fetches the external data required from the I / O port 54 according to the program written in the ROM 52, and exchanges the data with the RAM 53, while processing values necessary for controlling the air-fuel ratio of the engine. (For example, the fuel supply amount) is calculated, and the data processed as necessary is output to the I / O port 54. I
In addition to the throttle sensor 40, signals from the sensors and switches 41, 42, 44, 45, 46, 47, 48 are input to the / O port 54, and the signals Si, Sa, S _FICD , S _IGN , Sc and S _H are output.
The ROM 52 stores the calculation program in the CPU 51, and the RAM 53 is partially composed of a non-volatile memory,
Data used for calculation is stored in the form of a map or the like.
Therefore, the stored contents are retained even after the engine is stopped.

Next, the operation will be described.

FIG. 4 is a flowchart showing a learning map rewriting program, and P _{1 to} P _{10 in the} drawing show respective steps of the flow. This program is executed once every predetermined time. First, the normal air-fuel ratio feedback learning control is performed at P _{1 to} P ₄ . That is, it is determined whether or not the learning condition is satisfied at P ₁ . Here, the learning condition is satisfied, for example, when the following two items are satisfied.

The oxygen sensor output shifts the lean side slice level and the rich side slice level eight times each.

20 seconds or more existed in one section of a predetermined learning area allocated by the engine speed N and the basic pulse width Tp (here, the learning area is, for example, the engine speed N is 0 to 4000 rpm,
It refers to a region where the basic pulse width Tp is 0 to approximately 4 msec, and this learning region is divided into 56 sections corresponding to each operating state. The range of the basic pulse width Tp differs depending on the characteristics of the injector 7. ).

Auxiliary air system with P ₂ when the learning condition is satisfied (FI
CD) is ON (in this embodiment, the air conditioner switch 47 is ON), and when FICD is OFF, P ₃
Then, the deviation of the air-fuel ratio feedback correction amount α is calculated as a learning value. FIG. 5 is a timing chart of the air-fuel ratio feedback system when the base air-fuel ratio is lean,
Air-fuel ratio feedback correction amount at the time of the P ₃ air-OFF alpha is alpha = L [alpha (although, L [alpha learning value) calculating the deviation (learned value) from L [alpha by the fluctuation because the still dizzy on. Next, in P ₄ , the deviation calculated in step P ₃ is added to the learning value Lα to update Lα, and the learning value Lα updated in P ₅ is stored in a predetermined map (first area) and the current processing is performed. To finish. Meanwhile, after the FICD proceeds to P ₆ when ON, the read learned value L [alpha stored in the first region in the P ₅ is updated with P _4, this learning value P ₇ L [alpha
And the difference Δα from the air-fuel ratio feedback correction coefficient α calculated after the FICD is turned on. At this time, the air-fuel ratio feedback correction coefficient α still fluctuates over a certain value Lα ′ as shown in the timing chart of FIG.
_{At 8} , the deviation (learning value) of the air-fuel ratio feedback correction coefficient α from Lα ′ due to this fluctuation is calculated, and then P
_The deviation calculated in step P ₈ in step ₉ is Δα (= Lα'-L
Add to α) and update Δα. Next, Δα updated in P ₁₀ is stored in a predetermined map (map different from the map stored in step P _4; second area), and this processing ends. On the other hand, when the learning condition is not satisfied at P ₁ , the subsequent processing is jumped and the processing is finished as it is.

Based on the learning values Lα and Δα calculated by the above program, the fuel injection amount Te when the air conditioner is off and when the air conditioner is on is calculated according to the following equation.

When the air conditioner is off, Te = Tp × {α + (Lα-1)} ... When the air conditioner is on, Te = Tp × {α + (Lα-1) + Δα}, where Tp: basic pulse width In the embodiment, learning is performed by the auxiliary air system (FIC
D) FICE ON, not only when ON
When, and when the learning condition is satisfied, the deviation Δα between the learning map value Lα of the operating region stored in the first region and the learning value Lα ′ of the air-fuel ratio feedback correction coefficient calculated after the operation of the auxiliary load. Is calculated and stored in the second area as the change amount of the air-fuel ratio correction amount when the FICD is ON, and the FICD is changed from OFF to ON or ON.
When it changes from OFF to OFF, the correction based on the calculated air-fuel ratio feedback correction coefficient and the map values of the first and second regions is added to the calculation of the fuel injection amount Te.

Therefore, by making use of the learning value when the FICD is OFF and adding the deviation Δα to this, the error amount due to the start of the operation of the auxiliary equipment load can be quickly corrected, and when the FICD is ON near the idle time. Even if there is, an appropriate correction can be quickly added to improve the followability of the air-fuel ratio control. Therefore, it is possible to eliminate the deviation of the air-fuel ratio when the FICD is turned on, and it is possible to solve the problem pointed out in the conventional problems.

FIG. 7 is a diagram showing a second embodiment of the present invention, and the hardware configuration of this embodiment is the same as that of FIG. 2 shown as the first embodiment, and therefore its explanation is omitted.

FIG. 7 is a flow chart showing a program for rewriting the learning map at the time of idling. Steps for performing the same processes as those of the program of FIG. 4 of the first embodiment are denoted by the same reference numerals and the description thereof will be omitted and different steps will be given. The step numbers surrounded by the circles are attached to and are described.

In the program of FIG. 7, it is determined at P ₁₁ whether or not the engine is idle, and when idle, at P ₁₂ , it is determined whether or not the oxygen sensor 43 is activated. Predetermined cycle by the P ₁₃ for the oxygen sensor 43 is to resume predetermined periodic feedback control if activated (e.g., four cycles) to determine whether it has passed. When the predetermined period has elapsed, the routine proceeds to P ₂ , and when it has not elapsed or when the engine is not idle at P ₁₁ or when the oxygen sensor 43 is not activated at P ₁₂ , the subsequent processing is jumped and the processing is terminated as it is. .

Therefore, in this embodiment, the FICD is turned on at the time of idling.
At this time, the predetermined period feedback control is restarted and the deviation of the air amount change is appropriately corrected, so that the exhaust emission characteristics and fuel efficiency during idling can be remarkably improved.

(Effect) According to the present invention, by learning the difference between the air-fuel ratio correction coefficient calculated after the auxiliary load is operated and the learning value learned while the auxiliary load is not operating, By utilizing the learning correction coefficient in each operating state learned by the first learning means during the non-operation of the machine load, only the error amount of the air-fuel ratio control caused by the start of the operation of the auxiliary machine load corresponds to the second correction value. Since the learning value of the learning means is used to make a quick correction, the followability of the air-fuel ratio control can be improved, and the air-fuel ratio control can be performed irrespective of whether the auxiliary air system is ON or OFF, especially during idle time. The fuel ratio can be made appropriate, and exhaust emission characteristics, fuel efficiency, and drivability can be improved.

[Brief description of drawings]

FIG. 1 is a basic conceptual diagram of the present invention, FIGS. 2 to 6 are diagrams showing a first embodiment of the present invention, FIG. 2 is an overall configuration diagram thereof, and FIG. 3 is a solenoid valve with an adjusting mechanism 22. 4 is a flow chart showing a program for rewriting the learning map, FIG. 5 is a timing chart when the air conditioner is off, FIG. 6 is a timing chart when the air conditioner is on, and FIG. 7 is a timing chart of the present invention. It is a flowchart which shows the program of the learning map rewriting which shows 2nd Example. 7 ... Injector (operating means), 43 ... Oxygen sensor (air-fuel ratio detecting means), 47 ... Air conditioner switch (auxiliary equipment load detecting means), 49 ... Operating state detecting means, 50 ... Control unit (correction coefficient) Computing means, first
Learning means, second learning means, control means).

Claims (1)

[Scope of utility model registration request] 1. A) air-fuel ratio detecting means for detecting an air-fuel ratio of an intake air-fuel mixture, b) operating state detecting means for detecting an operating state of an engine, and c) auxiliary equipment loads such as an air conditioner and a power steering. The auxiliary load detecting means for detecting the operating state of d), d) the correction coefficient calculating means for calculating the correction coefficient for feedback-correcting the air-fuel ratio to the predetermined air-fuel ratio based on the output of the air-fuel ratio detecting means, and e) the learning is permitted. When the auxiliary load is not operating, the learning correction coefficient for matching the air-fuel ratio to the target air-fuel ratio is learned from the value of the air-fuel ratio correction coefficient as the value corresponding to the operating state at that time, and the learned value is learned. A first learning means stored in the corresponding first area; and f) a difference between the correction coefficient calculated after the operation of the auxiliary load and the learning value read from the first learning means during the operation of the auxiliary load. Driving at that time A second learning means for learning as the one corresponding to the state and storing the learned value in the corresponding second area; g) From the air-fuel ratio correction coefficient and the first learning means while the auxiliary load is not operating. The intake air or fuel supply amount is controlled so that the air-fuel ratio becomes the target air-fuel ratio on the basis of the correction coefficient read out as the learning correction coefficient corresponding to the operating state, and the air-fuel ratio correction coefficient is used while the auxiliary load is operating. And controlling the supply amount of intake air or fuel so that the air-fuel ratio becomes the target air-fuel ratio based on the correction coefficient read from the first learning means and the second learning means as the learning correction coefficient corresponding to the operating state. An air-fuel ratio control device comprising: a control unit for controlling the intake air or the fuel supply amount based on a signal from the control unit.