JPS6181537A - Control device for air-fuel ratio during shifting to feedback mode of internal-combustion engine - Google Patents

Abstract

PURPOSE:To enable rapid and smooth shifting to normal feedback control, by providing an operating state deciding circuit which discriminates the operating condition of an engine before shifting to a feedback control mode. CONSTITUTION:An engine operating condition deciding circuit 61 discriminates the operating condition of an engine right before shifting to a feedback control mode. A reference position register 56 is preset to a valve equivalent to a transient position outputted from a function generator 62. A driving direction switching circuit 59 outputs a driving signal to a driver 206 depending on an output from a comparator 58. The driver 206 feeds a driving pulse signal to a stepper motor 13. This enables rapid and smooth shifting of an operating state to a normal feedback control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an air-fuel ratio control device when an internal combustion engine shifts to feedback mode. By driving the chipper motor to a predetermined transient or interim position, the transition to normal feedback control (1) can be performed quickly and as smoothly as possible. This invention relates to a fuel ratio control device.

(Prior Art) A device for detecting the concentration of exhaust gas components of an internal combustion engine;
a fuel metering device that generates an air-fuel mixture to be supplied to the engine; and a fuel metering device that adjusts the concentration detection device so as to feedback control the air-fuel ratio of the air-fuel mixture to a set value in accordance with an output signal of the concentration detection device. Air-fuel ratio control devices for the air-fuel mixture supplied to an engine are well known in the art (e.g., in the Japanese Patent Application No. 57-6295
Publication No. 5).

Figure 2 shows the entire air-fuel ratio control device (111) as described above.
It is a complete drawing.

Reference numeral 1 indicates an internal combustion engine, and an intake manifold (intake pipe) 2 connected to the engine 1 is provided with a carburetor generally indicated by 3.

The carburetor 3 is formed with fuel passages 5 and 6 that communicate the float constriction 4 and the primary intake passage, and these passages are connected to an air-fuel conversion control valve 9 via air passages 8a and 8b, respectively. There is.

Generally speaking, fuel passages 7a and 7b are formed in the carburetor 3 to communicate the float 4 and the secondary intake passage. The passage 7a is connected to the air-fuel ratio control valve 9 via the air passage 8C, and is also connected to the throttle valve 30 of the secondary intake passage.
The frontage is slightly upstream.

Further, the passage 7b is an air passage 8d which is located on the right side of the fixed throttle.
It communicates with the inside of the air cleaner through.

The control valve 9 is composed of a 3UA flow control Do valve in the illustrated example, and each flow control valve includes a cylinder 10, a valve body 11 displaceably inserted into the cylinder 10, and a valve between the cylinder and the valve body. The coil spring 12 is mounted on the valve body and presses each valve body in one direction.

The anti-coil spring side end 11a of each valve body 11 is formed into a tapered shape, and depending on the displacement of the valve body 11, the opposite end frontage 1 of the cylinder 10 through which the valve body taper portion 11.1 is inserted.
The opening area of 0a is changed.

One end of each valve body 11 (the end on the opposite coil spring side) is the first point of reciprocation ii
It is in contact with a connecting plate 15 connected to a worm member 14 which is prevented from rotating so as to be able to rotate.

4-m part (A 14 is a radial bearing 1
The rotor 17 of the stepper motor 13 is rotatably disposed through the rotor 17 of the stepper motor 13 via the rotor 6 . Furthermore, a solenoid 18 serving as a stator is arranged around the outer periphery of the mouth 17.

The solenoid 18 is electrically connected to an electronic control unit 20 (hereinafter referred to as rECUJ).

When the solenoid 18 is energized by a drive pulse from the ECU 20, the rotor 17 rotates;
The worm member 14 that is threadedly engaged with the worm member 14 is displaced in the left-right direction in the figure. Therefore, the plate 15 connected to the worm member 14 is displaced in the left-right direction.

A permanent magnet 22 and a reed switch 23 are provided in a fixed housing 21 of the stepper motor 13 to face each other. On the other hand, a shielding plate 24 made of a magnetic material is attached to the peripheral edge of the plate 15 so as to be able to go in and out between the permanent magnet 22 and the reed switch 23.

As is clear from the above configuration, as the plays 1 to 15 are displaced in the left and right direction, the shield 24 is displaced left and right.Furthermore, according to this displacement, the reed switch 23 is controlled to turn on and off. .

That is, when the valve body of the air-fuel ratio control valve 9 passes through the permanent magnet 22, the reed switch 23, and the position determined by the position of the The switch 23 is turned on or off.

The reed switch 23 supplies the ECU 20 with a binary signal corresponding to this on/off moxibustion.

6. An air intake port 25 communicating with the atmosphere is formed in the housing 21, and the air is supplied to each flow rate control valve via a filter 26 attached to the intake port 25.

On the other hand, in 11 of the engine exhaust manifolds 27,
An 02 sensor 28 made of zirconium oxide or the like is provided protruding inside the manifold 2, and its output (from the ECU
20.

Further, an atmospheric pressure sensor 29 is arranged so as to be able to detect the atmospheric pressure around the pi vehicle on which the engine is mounted. A detectable signal from the atmospheric pressure sensor 29 is also supplied to the ECU 20.

Further, a thermistor 33 is installed in the circumferential wall of the engine cylinder filled with cold engine water to detect the cooling water temperature representative of the engine temperature. The detected value signal of the thermistor 33 is also supplied to C20.

In addition, in Fig. 2, the symbol g:339 indicates C in the exhaust gas.
o, three-way catalyst for purifying HC and NOx, 31 is pipe 3
2 through the throttle valve 30'a.

1F Calendar ° which detects the intake pressure in the intake manifold 2 downstream from 30b and feeds its output to ECIJ 20, 35 is engine rotation, :) 7 i
, L ignition switch.

Next, the above-mentioned conventional control contents of the air-fuel ratio ai (I i '&) will be explained with reference to FIG.

First, when the engine is started and the ignition switch 37 is turned on, the FCtJ20 is set to the initial V.
It is riced (initialization). Thereafter, the ECU 20 detects the reference position of the stepper motor 13, which is an actuator, via the reed switch 23.

13. above j; ti (ζ position is stepper motor 1
It is detected based on the position when the reed switch 23 of No. 3 is turned on or off.

Next, the ECU 20 moves the stepper motor 13 from the reference position to a predetermined position 17 that is optimal for starting the engine. (
(hereinafter referred to as f''PScrJ), and the initial two fuel ratios are set to predetermined corresponding values.

Next, E CU 20 is 02'l? The activation state of the engine 1t28 and the engine cooling water level detected by the thermistor 33 are monitored to determine whether or not the air-fuel ratio control conditions are met.

In order to accurately perform air-fuel ratio feedback control O, (1
) 02 sensor 28 has risen sufficiently in temperature and is in an activated state, and the ('2J engine is in a state of
It is necessary that two conditions are satisfied:

Further, the 02 metal made of zirconium oxide or the like has a characteristic that its internal resistance decreases as the temperature increases.

If a current is supplied to the Q2 sensor with such characteristics from the constant voltage source built into the E CLJ 20 through an appropriate resistance (direction is set to the right), the output voltage V will be the same as the constant voltage source when inactive. voltage (e.g., 5 volts), and its 'f? As na increases h',j, the output voltage decreases.

Therefore, when the output voltage of the 02 sensor drops to a predetermined voltage 1]: V Then, open the automatic choke to a degree that allows feedback AI control of the air-fuel ratio. Start air-fuel ratio feedback control.

3. During the detection stage of this Ozt sensor activation cold water temperature TW, the stepper [-ta 13 is held at the predetermined position PScr described by i'+ff for one night, and the stepper 13 is held at the predetermined position PScr described by When i, II i2'Il are completed, the system shifts to Hoshiki air-fuel ratio control.

In addition, the FCU 20 receives the output signal V from the 02 sensor 28, the absolute pressure PB in the intake manifold from the pressure sensor 31, the engine speed Ne from the rotation speed sensor 35,
According to the human pressure PΔ from J5 and the atmospheric pressure sensor 29,
The stepper motor 13 is driven 11' to the point 11' to set the air-fuel ratio to a predetermined value.

More specifically, this basic air/fuel ratio control includes (1) open-loop control when the throttle valve is fully open, (■ idle port 1), and (3) open-loop control during deceleration, and (4) closed-loop i+lI during partial load. Note that all of these Jill 011s are turned off after the engine reaches the warm-up state.

First, the open loop control conditions when the throttle valve is fully open are the absolute pressure PB detected by the pressure sensor 31 and the atmospheric pressure detected by the pressure sensor 29! Atmosphere 11 (He N JE
E) P A to (7) Caseri-difference (P△-
This is true when Pr3) is lower than a predetermined arrival ΔP.

The ECU 20 compares the output signals of the sensors 29 and 31 with a predetermined difference ΔP recorded in the IQ.

When the above conditions are met, the stepper motor 13 is moved to a pre-hint position (pre-hint position) that provides the optimum air-fuel ratio for engine emissions when the A-bun loop control condition when the throttle valve is fully open is extinguished. )p3wot
It is driven until it reaches and is stopped at the predetermined position.

In J-3, when the throttle valve is opened, a well-known economizer (not shown) or the like operates to supply a rich air-fuel mixture (low air-fuel ratio) to the engine.

The Δ-thin loop control condition of the idle port 3 is that the engine speed 7jl i'4 Q is the predetermined idle speed N1dl
(For example, 151 holds true when the rpm is lower than 101,000 rp.

E CU 20 i, t, output signal NG of rotation speed sensor 35 and predetermined rotation speed N1dl stored therein
When the above conditions are satisfied, the stepper motor 13 is driven until it reaches a predetermined idle position (preset position>p3i(ll) if the engine's emissions are resistant to it, and is stopped at the predetermined position. Next, the oven loop control conditions during deceleration are as follows:
1. The absolute pressure PB in the lead is a predetermined absolute pressure PBdecJ,
It is established when the situation is low.

The ECU 20+ compares the output of the pressure sensor 31 (with a predetermined absolute pressure p B dec stored inside the Δ PB etc., and if the above conditions are met, the stepper motor 1
3 to the predetermined deceleration position > P S +
Drive the 1cC5 until it reaches the 2nd position, and stop it at a predetermined position.

The reason for the above-mentioned oven loop control conditions during deceleration is that when the absolute pressure PB in the intake manifold drops below a predetermined value (just below) due to deceleration, unburned 1-IC (hydrocarbons) in the exhaust gas
increases, and as a result, 02t? The problem is that the air-fuel ratio feedback control based on the detected value signal of the sensor cannot be accurately performed, and the stoichiometric ratio or air-fuel ratio of the air-fuel mixture cannot be determined.

Therefore, as mentioned above, as long as the pressure []B in the intake manifold detected by the sensor 31 is smaller than the predetermined value p 3 dec, the actuator (
Stepper motor), when the A-pun loop control conditions of deceleration l, 'l disappear, the air-fuel ratio that is optimal for engine emissions is 1! , a predetermined position (preset position) P
It is an IC device that moves to Sdec and performs control using an oven loop.

In addition, in each open loop control during the throttle 1 valve interval, idling, J3 and deceleration, the human'v
+ R-P△, each stepper motor 13
Predetermined positions of PSwot, PSidl, PSde
It is desirable that c be appropriately corrected.

On the other hand, each oven loop a+'l i) under the closed-loop control condition at partial load (Y, engine, @)
It is established when the condition is in an operating state other than when the 0 condition is satisfied.

In this closed loop control, the ECU 20 controls the engine rotation speed Ne detected by the rotation speed sensor 35.
and, depending on the output signal V of the 02 sensor 28, proportional ll1l control (hereinafter referred to as "1-term control") or integral control (hereinafter referred to as "1-term control") by feedback is performed.
IIJ Toiu) wo line 1. ; cormorant.

For further revision, the output voltage of the 02 senna 28 is set to a predetermined voltage v
If only the higher level side or lower level side C changes than ref (the town corresponding to the stoichiometric temperature ratio or air-fuel ratio of the air-fuel mixture), execute the item 11112n.

In other words, the output voltage of the 02 sensor is equal to the predetermined voltage yrcr
, the position of the stepper motor 13 is corrected to the high level side or (according to the value obtained by dividing the binary signal corresponding to the lower level side by 16), and stable and accurate position control is performed. .

On the other hand, the output signal of the 02 sensor 28 is 1. When the platform changes from the crow level side to the low level side, or vice versa, from the low level side to the high level side (the hit platform executes the 1-term control.
The position of the stepper motor 13 is corrected in accordance with the 1-paragraph which is directly proportional to the output voltage of the 02 sensor, and the control is faster and more efficient than the 1-parameter control.

In the above-mentioned 1-term control, the position of the stepper motor is changed according to the change in the output voltage of the 02 sensor by dividing the binary signal into h'i and changing the position of the stepper motor according to the value Ci:i. The number of steps to increase or decrease is changed according to the engine speed.

In other words, the number of steps increased or decreased per second by II0 control (all) at low rotation speeds is small or increases according to the upper limit of the rotation speed, and the number of steps increased or decreased per second at high rotation speeds is controlled to be large. .

In addition, in P In control that is performed when there is a change in the Oz sensor output from a high level side to a low level side or in the opposite direction with respect to a predetermined voltage V ref, the stepper motor which increases and decreases every second The number of steps is -? 11 are set to the same predetermined value (for example, 6 steps).

Furthermore, the air-fuel ratio till the engine zero R advance - acceleration time
i is the engine rotation speed Nc when engine warming is completed;
At the stage when the engine moves from a low speed rotation range to a high speed rotation range, the predetermined idle rotation speed N1dl (for example, 101000
This is done on the condition that rp is exceeded.

When this condition is satisfied, the ECU 20 moves the stepper Tanabata 13 to a predetermined acceleration position (brilet position).
Avoid rapid transition to p3acc. Immediately after this, the ECU
20 starts the air-fuel ratio feedback control described above.

As mentioned above, the engine's zero r+ 5i jq, -In
For n-speed ■, change the actuator position to
) at a predetermined preset position PSacc1. :+g
Turn on the ir.

Therefore, accelerating the engine-equipped i#I from the parking position, d5, is advantageous in terms of exhaust gas countermeasures, and it is possible to perform good air-fuel ratio feedback afterwards. becomes.

When transitioning from the various open-loop controls described above to closed-loop control during partial machining and vice versa, turning off the a1 control motor at d5 is performed as follows.

First, when switching from a closed loop to an oven loop, the ECU 20 sets the preset positions PScr, P3wot, and fjli /Z of fjli /Z during the open loop described above, regardless of the position of the stepper motor 13 immediately before entering each oven loop state. P3idl.

Stepper motor 1. to P3dec or p3acc (corrected for atmospheric pressure if necessary). '1 rapidly. This makes it possible to immediately start oven loop 1+ control according to the engine operating state of each machine.

On the other hand, when switching from oven loop to closed loop, stepper 1-91 is switched by the command of ECtJ20.
3 starts air-fuel ratio feedback control by l If mode.

The reason for this is that the timing at which the output signal level of the 02 sensor switches from the high level side to the low level side, or vice versa, is not necessarily constant with respect to the timing at which the oven loop changes to the closed loop. In such a case, the position difference of the direct stepper motor 13 that is not switched to the closed loop can be made smaller when the feedback control is started using the I top control than when the air-fuel ratio feedback 1VIIIi2iI is started using the p IQ control. This enables accurate air-fuel ratio control at an early stage, resulting in high emissions stability↑!
This is because 1 is considered to be the armored desk.

In addition, air-fuel ratio i, I + control valve 9 actuation. 1 eta
C The position of the stepper motor 13 used is ECU 20
The stepper motor is monitored by a position counter (up/down counter), but due to step-out or disturbance of the stepper motor, a discrepancy may occur between the counter contents and the actual position of the stepper motor. .

In such a case, the ECU 20 operates by regarding the count value of the counter as the actual position of the stepper motor 13. may interfere with control operations.

Therefore, in the air-fuel ratio control system shown in FIG. By presetting a position step number (e.g., 50 steps) in the position counter, subsequent
An attempt is made to ensure f+'i degrees.

(Problems to be Solved by the Invention) The above-described conventional techniques had the following problems.

1,771% from oven loop to closed loop
I14[, i.e. 1 at 11 o'clock when switching to feedback mode.
j) tried to achieve positive air-fuel ratio control at an early stage using air-fuel ratio feedback control using the one-term mode. .

? l-'; C, the stepper motor reaches the target position ↑1
It took too much time to reach 1, and as a result, it was difficult to realize a quick transition to normal feedback control.

The present invention has been made to solve the aforementioned problems.

(Means and actions for solving problems).

In order to solve the above-mentioned problems, the present invention provides:
By driving the stepper E-1 to a transient or temporary position predetermined experimentally or empirically,
The position difference of the stepper Tanabata immediately after switching to the feedback a-ratio line is made smaller than that of the conventional one, so that accurate air-fuel ratio control can be realized even earlier (j4). There are characteristics.

(Implementation fIA) The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

In the figure, the same r:F month as in FIG. 2 indicates the same or equivalent parts.

The ECU 20 includes a computer section 200, an input interface 202 for connecting the computer section 200 to an external circuit, an output interface 204, and a driver 206 connected between the output interface 204 and the stepper motor 13.

The computer section 200 may be of a well-known type, and may include a CPU 20.
1, RAM 205, ROM 203, and a common bus 207 for exchanging data and instructions between them.

02sen+L 28, TW sensor 33, Ne sensor 35
TH sensor 4 detects rr3 and throttle valve angle
Each detection output such as j208 is input to the input interface 7th chair 2.
02 to the computer section 200.

Further, FIG. 3 is an open block diagram for explaining the present invention in detail.

In FIG. 3, when switching from open-loop control to feedback control, for example, the engine operating state determination circuit 61 determines the engine operating state immediately before switching to the feedback control mode 1, and outputs a determination signal accordingly. do.

The function generator 62 outputs a composite value signal corresponding to the determination signal from among preset values of the compound λ stored in advance. As a result, base I (1 position register 56
is preset by the preset value signal to a value corresponding to a transient position corresponding to the engine operating state of 1) fl immediately before transition to feedback control.

The type of this preset value signal is Honjitsu/+l! In example i [
; 1. Those corresponding to idling, high speed, acceleration, deceleration, and other five previous modes are kept constant at 1.

In addition, with respect to the position of the stepper motor 13 in each of the above-mentioned modes (idling, high speed, acceleration, deceleration, and 11!! modes) during oven loop control, the stepper motor 13 when switching to feedback control The 13 transient positions and therefore the preset values of the Q t,p+ position register 56 are determined in advance experimentally or empirically.

When the reference position register 56 is preset to the above-mentioned scheduled value, the difference between the count value of the up-down counter 57 indicating the current position of the stepper motor 13 is determined by the comparator 5.
8, and a pulse signal corresponding to the difference is output to the drive direction switching circuit 59.

That is, if the preset value of the up/down counter 57 is large, a pulse signal with a higher level than the reference level is output, and if it is small, the reference level is A pulse signal with a level lower than the level is output.

The drive direction switching circuit 59 outputs a (+> direction drive signal or a (-) direction drive signal to the driver 206 in response to a pulse signal having a level higher or lower than the reference level which is the output of the comparator 58). .

The driver 206 outputs drive pulse signals corresponding to the two types of directional drive signals. As a result, the stepper motor 13 is moved to a position 1i11 lit in the predetermined direction according to the drive pulse signal.

Note that the (+) direction or negative) direction drive signals, which are the outputs of the five drive direction switching circuits, are also supplied to the up/down counter 57. As a result, the count of the 7-up down counter 57 (directly, the prepit value of the reference position register 56) is added or subtracted by ``1'' in the direction of 1f.

Then, when the count 1-1 of the up/down counter 57 matches the preset 1 count of the qQ position register 56, the feedback mode shift 11 control ends.
The pulse 1.1\'''i, which is the output of the comparator 58, disappears. Therefore, the stepper output from the driver 206 -41
The drive pulse signal applied to d'j also disappears.

3. During this feedback mode transition control, 15
Come on, power! ) becomes lower than the regulation flCj E 1 that allows drive control of the stepper motor 13 to Masatomi i2D, Junsho signal 2; is output from the low electronic determination circuit 60 to the five drive direction switching circuits.

As a result, at this time, the drive pulse signal is not output from the driver 206, so the feed bar/y U-- (31TE1llll11Tl) is interrupted.

Next, referring to the flowchart of FIG. 4, feedback U knee 1 to 1 according to the embodiment of the present invention shown in FIG.
The operation of the transition gate ■ will be explained in detail.

351...1 When it is determined in step S30 of FIG. 5 that the current control mode is feedback control and the process advances to step S51, in step 351, step S17 of FIG. In,
It is determined whether the feedback flag has been set as the previous control mode. If the determination is successful, the process advances to step 35214. Feedback system tfllE
At the beginning of the - code, this determination is not true, so the process advances to step 55201.

55201...In step S17 of FIG. 5, a determination is made as to whether or not eye 1 to flag flags have been turned on as the engine operating state for the turn. If the determination is true, the process advances to step 55202, and if the determination is not true, the process advances to step 85203.

55202...This is an IJI letter written by the engine of the song "
For example, a preset value of the reference position register corresponding to a transient position of the stepper motor 13 determined experimentally or theoretically in response to "idle" is selected (e.g., read from a table), and this value is set in the reference position register. Set to .

35203...J-3 is in step 317 of FIG. 5, and it is determined whether the high speed flag is set or not as the engine is in a J condition during the turn. If the determination is established, the process advances to step 55204. If the determination is unsuccessful, the process advances to step 55205.

35204...Similar to step 35202, select the recent jet in the reference position register corresponding to "high speed" and set it in the reference position register.

55205...J3 is at step S12 in FIG.
It is determined whether the acceleration flag is between 1 and 1 as the previous engine operating state. If the determination is true, the process advances to step 35206, and if the determination is not true, the process advances to step 55207.

S 5206-nffff destep 55202 (,
Select the reference position movement register 1-1 straight corresponding to "r + III speed" and pit it in the base tt town f v stomach register.

55207...In the fifth (71st step S17), it is determined whether the deceleration flag is set as the previous engine operating state. If the determination is established, the process proceeds to step 55208, and if the determination is not established, the process proceeds to step 85209. move on.

55208...Similar to step 55202, select the preset value of the qilj price position star corresponding to "deceleration" and set this in the reference position register.

55209...IQ that the previous engine operating state was idle, high speed, acceleration, and deceleration.
In this case, select a preset value of a certain reference position register and set it in the base fl (position register. .

35210...Up-down counter counting field (
That is, it is determined whether the current position (B) of the stepper motor 13 is equal to the bullet 1 set in any of the previous steps 55202, 5204, 5206, 5208, and 5209. If this determination is established, the process proceeds to step 55215; if not, step 552
Proceed to step 11.

5b211... In step S16 in FIG. 5, it is determined whether a flag indicating that the power supply voltage is lower than the specified 1st voltage E1 is set.

When the flag is set, there is a risk that accurate position control of actuators such as the stepper motor 13 may not be possible, so nothing is done and the process returns to the main program. If the flag has not been sent, the process advances to step 35212.

55212...Drives an actuator such as the stepper motor 13 one step in the direction closer to the preset value set in the previous step, and increments the up-run counter by +1 or -1.

S5213: Sets the feedback control flag and returns to the main program.

55214...Next, ffi I'l! in Figure 4! If it is, the determination in step S51 is true, so the process goes to step 55214. Here, it is determined whether the feedback quasi-first flag is set.

If the determination is not established, the process returns to the main program, but if the determination is established, it is determined that the actuator has not been driven to the position corresponding to the value of Brisera 1, and the process returns to step 35210.

Then, steps S51 and S52 are performed until the actuator is driven to a position corresponding to the preset position.
1 /I, J3 and to step 55210-5213
The judgment and processing are repeated 1-111. As a result, if the judgment of step 55210 is established, slap 55215
Proceed to.

55215...Resets the feedback preparation flag set in step 85213.

Therefore, after this process is performed, the step 3521
The determination of /I is not established, and the process proceeds to the original feedback control as described with reference to FIG.

As is clear from the above description, according to this example,
During feedback mode transition control, stepper motor 1
3 is provisionally set at the transient position, the same feedback mode as the conventional 13th line i+'l 13
n l: In comparison, the position difference of the stepper motor 13 immediately after switching to feedback control can be further reduced.

Roughly speaking, this feedback mode transition control allows
Compared to the conventional example, an accurate air-fuel ratio subsurface can be achieved much earlier, and therefore, even higher emission stability can be achieved.

FIG. 5 shows the air-fuel ratio control i of an internal combustion engine to which the present invention is applied.
11 is a starting point for explaining the overall control operation of the 11 device. , 6. This cutting operation can be performed by the ECU that constitutes + in FIG. 1.

S11: When the ignition switch 37 is turned on, the ECU 20 is first initialized by a known method.

S12...The current throttle opening value is read and the closed state and opening range are determined during that time. Both of these determine whether or not the engine is required to accelerate.

When the vehicle is in the acceleration state, the +111 speed flag is set to 1-, and the acceleration hold flag is set for the scheduled time after the end of acceleration.

S13...T W t Read the output of the fusa 33, determine whether the engine temperature has risen above the planned field, and if it is above the planned value, it is assumed that the warming period has been completed, and E fj ! Lottery completion flag.

S14...02 A 1'11 determination is made as to whether or not the ton 128 is activated. As described above regarding the conventional example, in order to accurately perform feedback control of the air-fuel ratio, it is necessary that the 02 sensor 28 be sufficiently activated.

Furthermore, whether the cI is also sexualized can be determined by comparing the output voltage of the 02 sensor 28 with 阜·l'-[. If it is confirmed that the 02 sensor 28 is sufficiently activated, the activation flag of the 02 sensor 28 is checked.

As is well known, the output of the S15...02 sensor 28 is 1'[! When the air-fuel ratio reaches 1, it becomes lower on the lean side, and becomes lower on the rich side.

In this step, it is determined whether the air-fuel mixture is on the lean side or the lip side based on the output characteristics of the O2 sensor 28, and the output is reversed from the lean side to the rich side or vice versa. Determine whether it has been done and set the respective flags.

S16... It is determined whether the power supply voltage VB of ECtJ20 is within a specified range. Suappa Seventa 13 is
If the power supply voltage VB is equal to or higher than the specified value E1, it will operate accurately. That is, accurate position control is possible without stepping out of synchronization or making abnormal movements due to external forces.

However, if the power supply voltage VB falls below the lower limit [2],
Regardless of the pulse signal h(1) applied to the solenoid 18, the stepper motor 13 will be moved irregularly by external force, making accurate position control impossible.

Furthermore, when the power supply voltage VB is between the current fixed level and the lower limit E2, the stepper motor 13 is moved irregularly by an external force. There is a possibility that the pulse application and the four-wheel drive of the stepper motor 13 do not correspond accurately.

Therefore, if the power supply voltage is lower than the specified value E1, 1.
1. If the accurate position control (feedback III and oven loop control) of the stepper motor 13 is not proven (?) and the power supply voltage further decreases below the lower limit value E2, the actual position of the stepper motor 13 and 1 ) in chapter 11
Accurate correspondence with the count value of the up/down counter 57, which should not represent the head, is not guaranteed.

In this S16, it is determined in which region the town of the power supply voltage is located, and respective flags are set.

S17... Based on the states of various flags based on the processing in each step described so far, and the results (flags) of the engine rotation speed range determination (described later with reference to FIG. 6), the engine operation fh state, 115 and the operating state of the
Determine which of the control areas it is in, and check each flag.

The operating status of the engine is t, stationary, fetal movement, warm-up, hot restart, idling, zero start acceleration, deceleration, acceleration,
High speed (throttle valve fully open), etc.

In this step S17, it is recommended to memorize both the currently detected operating state and the previous operating state detected immediately before, as well as their respective controls (feedback control or oven loop control). It's advantageous.

318... Determine whether initialization of the actuator (ie, stepper motor 13 and connection plate 15 shown in FIG. 2) has been completed. This determination is made by referring to an acquisition completed flag provided within the ECU 20.

If initialization is not completed, step S19
Proceed to. Note that in the cycle immediately after the ignition switch 37 is turned on and immediately after the power supply voltage If- drops below the lower limit value E2, this determination does not hold.

819... Determines whether the initial processing flag is set. Since it is not set at first, the process advances to step S20. If the determination is true, step 320 is jumped and the process proceeds to step 521.

320...The reference positions of the actuator, that is, the stepper motor 13 and the connecting plate 15 are set.

The reference position is preferably a position in which the stepper motor 13 is driven to its full right or left end in FIG. 2. In the example of FIG. 3, this corresponds to setting the reference (target) position register 56 to, for example, O''.

At the same time, the up/down counter 57 is set to ft, for example "100", which corresponds to the pant on the opposite side. After that, a flag indicating that initial processing is in progress is set.

S21... Count of the up/down counter representing the current position of the stepper motor 13 (direct (for example, "100")
”) is equal to 1 (in the present example, 'o') which corresponds to the reference position (the value stored in the reference position register).

At first, this judgment does not hold, so the 98 principle goes to step 8.
Proceed to 22. If the determination becomes true, the process advances to step S24.

822...It is determined whether or not a flag indicating that the power supply' voltage is lower than the specified value E1 has been set in the previous step S16.

When the flag is set, there is a risk that accurate position control (initial processing) of actuators such as the stepper motor 13 may not be possible, so the process returns to step 312 without doing anything. If the flag is not set, the process advances to step S23.

S23...Drives an actuator such as the stepper motor 13 in the direction of the reference position set in step S20,
Increase the count value of the up/down counter by 1 or -1
do. In other words, in the present example, the stepper motor 13 is moved in the direction of decreasing the count value of the up/down counter.
is driven, and at the same time the up/down counter is decremented by 1.

After that, the process returns to step 812, and thereafter steps 812 to 23 are repeated until the determination in step 821 is satisfied. However, in this case, since the determination in step 819 is established, the process in step 320 is omitted.

Each time the loop of steps 812-23 is cycled through as described above, the stepper motor 13 moves one step at a time to the base 111.
Since it is driven toward the position, the determination in step 321 finally comes to be true.

In this case, the actual position of the stepper motor 13 at the point when the initial processing is started is different from that of the stepper motor 13, assuming that the stepper motor 13 is at one end of its movable range in FIG. The number of pulses necessary to drive the stepper motor 13 to the opposite end reference position will be supplied to the solenoid 18 during the cycle of steps 312-23.

Therefore, in general, according to this initial processing method, extra drive pulses will be supplied to the solenoid 18 after the stepper motor 13 reaches the reference position.

However, in this state, since the movement of the stepper motor 13 is mechanically blocked, it is not driven beyond the base position, and the stepper motor 13 is completely moved to i!
The reference position is set, and the initials of )'ri-f-yuu-yu are completed.

824...Reset the actuator initial lye flag and set the actuator initial completed flag at the same time.

830...In the previous step S17, it is determined whether the current control mode is feedback control mode, that is, whether the feedback control flag is set. When the flag is set, the process advances to step S51 to perform feedback IIL control, and when it is not set, the process advances to step S41 to perform open loop HIL control.

S41: Preset the reference (target) position register corresponding to the preset position of the stepper Tanabata 13, corresponding to the current engine operating state (flag) set in step S17. For example, if you want to read from a table), use this as the standard (for example, read from a table).
Target) Set in the position register 244.

No, this preset 1m is oven loop system i?
1, which is common to all engine operating conditions beyond Il.
It can also have two fixed positions.

S42: Determine whether the count 1 of the up/down counter (that is, the current position of the stepper motor 13) is equal to the brilet value set in the previous step. If they are equal, the process returns to step 312; if not, the process proceeds to step S/I3.

S43: The level of the power supply voltage is determined in the same manner as in step S22 of the previous step.

S44: The actuator such as the stepper motor 13 is driven by one step in the direction approaching the preset field set in the previous step S41, and the up/down counter is incremented by +1 or -1.

- By repeating the processing of steps 841 to 44 described above, the actuator is driven to a position (directly corresponding to the preset set in step S41) and fixed there.

S51...In the previous step S17, the previous step a11
It is determined whether the feedback flag is set as 1i++ mode. If the determination is not established, proceed to step S52, and if the determination is established, step S5
Proceed to step 3.

S52...According to which range (see Fig. 7) the engine operating state has fallen just before shifting to feedback control, a predetermined transient (adjustable) drive the stepper motor 13 to the position.

1) As is clear from the explanation above, the stepper motor 13
As soon as the count of the up/down counter representing the position of (direct) becomes equal to the memory contents of the target position register representing the transition position, the 51st position "f'? The setting is completed. Then, the process returns to step 312.

S53...Fu11('s time/frequency division table (part 1)
1 is shown in Figure 8 and will be explained later)
, the basic frequency division rate is predetermined as a measure of the elapsed time since the reversal of the exit horn of 02 Kensa.

It doesn't read out. Next, the engine temperature TW determined in the previous step, the throttle membrane (direct, Δ'3, and

The basic frequency division ratio DO is corrected and the frequency division ratio is calculated using the engine rotation failure region obtained by the process shown in FIG.

Alternatively, by using the engine temperature TW, inter-throttle degree value, and engine speed fiV< as parameters, prepare many time/frequency division ratio tables corresponding to the combinations of these parameters (![). Alternatively, a specific time/frequency division ratio table may be selected according to the combination of the engine parameters, and the frequency division ratio may be determined based on this table.

Note that at the stage of first moving to this step S53,
Since it is impossible to know the elapsed time since the output reversal of the 02 centimeter described above unless a means such as a counter is specially prepared to measure this time, preset 1, which is predetermined as the elapsed time, cannot be known. Based on this, the basic frequency division ratio DO described in NFR is calculated using the direct current, and feedback control is performed.

On the other hand, it is determined whether the status flag of the 02 sensor 28 obtained in step 315 is on the lean side or the rich side of the air-fuel mixture, and the direction in which the stepper motor 13 should be driven (the air-fuel mixture is set to the ITIu stoichiometric fuel ratio) is determined. direction).

354...Judge the power supply IE range as in step S22 above? 1 Now.

S55...According to the frequency division rate, it is determined whether or not the raccoon of the ECU 20 has passed through the branches of steps 353 to 55 D times, and at the D time, the stepper [-13
is driven by one step in the direction specified in the previous step S53. As a result, the air-fuel ratio of the air-fuel mixture approaches the stoichiometric air-fuel ratio.

FIG. 6 is a flowchart V showing the procedure for determining the engine rotation training area.
- It is.

S71...If an engine pulse is generated by the Ne sensor 35, the computer section 20
An interrupt 77 is set to 0, the count value of the interrupt opening counter is read, and the counter is reset.

Alternatively, the engine rotation period can be determined by reading the clock timer and multiplying it by the previous reading.

S72: Determine the engine rotation speed region based on the lζζ rotation periphery obtained as described above. The rotational speed range of the engine is determined as shown in FIG. 7, for example.

In FIG. 7, the horizontal axis is the engine rotation speed Ne (that is, the reciprocal of the rotation period), and the vertical axis 111 is the throttle distance value TH.

In this figure, the engine rotation speed region is divided into five regions, with the rotation speeds N1 to N4 as a boundary, and roughly divided into two revolution regions based on the throttle opening degree IUTH. As a result, the engine operating region as a whole is divided into ten regions (1) to (10).

As can be easily understood from the figure, areas (1) and (2)
) is the first spinning/idle area, (3) is the deceleration area, (4) [
This is a high-speed region, and when the engine operation yields to these regions, open-loop control is performed.

Further, the remaining E (5) to (10) are normal cruise ranges, and when the engine operating state belongs to these ranges, feedback control is performed unless it is determined to be an acceleration state or an acceleration holding state.

In addition, the apex of each arrow in FIG. 7 indicates the feedback control 'x+
An example of an engine operating point corresponding to a transient (angular constant) position (see step S52 in FIGS. 4 and 5) when moving to LU is shown in No. 1.

8171(a) is a time chart showing the output reversal state of the 02 sensor 28, and FIG. 8171(b) is a time chart showing the position change of the stepper motor 13 for air-fuel ratio control.

When the output of the 02 sensor 28 is reversed from the rich side to the lean side, the stepper 1 yawter 13 is driven to the side that makes the aiki richer.

At that time, depending on the time elapsed from the time of inversion, a relatively small frequency division, f′ (small clock count), C
The stepper Tanabata 13 is driven one step every time C2, but as time passes, the stepper Tanabata 13 is driven one step every relatively long time C2.

Therefore, the moving speed of the stepper 13 decreases immediately after the output of the 02 sensor 28 is reversed, and gradually decreases as time passes. The elapsed time of nir,
The relationship between the corresponding frequency division ratio or clock count attack is stored in the nir (with respect to -nisdeep S53) time/frequency division ratio boolean.

(Effects of the Invention) As is clear from the above description, according to the present invention, the following effects are achieved.

Since it was decided to drive the stepper motor 13 to a predetermined transitional or provisional position in accordance with the engine IY sagittal suspension immediately before shifting to feedback control, 1.
A transition to sophisticated feedback control can be performed quickly and smoothly.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a schematic diagram 11-1 of a conventional air-fuel ratio control 12Il gas charging system for an internal combustion engine.
Fig. 3 is an Ir diagram for explaining the 177th work of the present invention.
"r l!u block diagram, FIG. 4 is a flowchart for explaining the present invention in detail, and FIG. 5 is an overall diagram of the air-fuel ratio control device for an internal combustion engine to which the present invention is applied: ii'
A flowchart for explaining the control operation, FIG. 6 is a flowchart showing the procedure for determining the engine rotational speed region, and FIG. 7 is for the engine rotational speed 77 N c and the throttle angle value T
Figure 8 (
Figure a) shows the time delay that shows the output reversal state of the 02 sensor, and figure (1) shows the time delay that shows the position change of the stepper motor for air-fuel ratio control. - It is. 13...Stepper motor, 20...E CU, 28
...02 sensor, 33...TW sensor→ノ, 35...
- Engine rotation speed sensor, 56... Base IM position register, 57... Up/down counter, 58... Comparator, 59... Drive j direction switching circuit, 200... Computer section, 206...・Driver, 208...T
Ht Nsa Patent Attorney Michito Hiraki and 1 other person Figure 16 Figure 7 H

Claims (1)

[Claims] (1) A device for detecting the concentration of exhaust gas components of an internal combustion engine, a fuel metering device for generating an air-fuel mixture to be supplied to the engine, a stepper motor for controlling the air-fuel ratio of the air-fuel mixture, and the concentration An air-fuel ratio control device for controlling the stepper motor in response to an output signal of a detection device, the feedback control device driving the stepper motor so as to bring the air-fuel ratio of the air-fuel mixture close to a set value. an engine operating state determination circuit that determines an engine operating state before shifting to a control mode; a function generator that generates a preset value signal according to an output of the engine operating state determination circuit; and a function generator that is supplied with the preset value signal. , compares a reference position register that is preset to that value, an up-down counter that represents the current position of the stepper motor, and the preset value and the count value of the up-down counter, and outputs a signal according to the difference. a drive direction switching circuit that supplies a (+) direction drive signal or a (-) direction drive signal to the up/down counter and a later-described driver according to the output of the comparator; An air-fuel ratio control device for an internal combustion engine when transitioning to a feedback mode, comprising: a driver that supplies a drive pulse signal to the stepper motor according to the signal.