JPS6181540A - Control device for air-fuel ratio during warming-up of internal-combustion engine - Google Patents

Abstract

PURPOSE:To provide the optimum air-fuel properties of an engine throughout the whole range of a warming-up state, by providing a device which stores the reference (desired) position of a stepper motor and a device which drives the stepper motor to a reference (desired) position during warming-up. CONSTITUTION:An A/D converting circuit 210 detects the temperature value of an engine. A comparator 220 outputs a warming-up state signal when the temperature value of an engine is below a warming-up completing temperature value. An engine operating state deciding circuit 242 sets a reference (desired) position signal from a stepper motor 13 to a reference (desired) position register 244. A stepper motor driving pulse feeding circuit 246 drives the stepper motor 13 to a reference (desired) position during output of a warming-up state signal. This enables provision of the optimum air-fuel properties of an engine throughout the whole range of a warming-up state.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is applicable to the warm-up period of an internal combustion engine. This relates to the heat ratio control system 2, and in particular, the internal combustion engine during warm weather, which can appropriately control the air-fuel ratio between warm and light temperatures in response to the rise in engine temperature during warm weather. Air-fuel ratio control 21'l device 1. : This is Chino Seki.

(Traditional gijutsu) A device that detects the concentration of exhaust gas components of an internal combustion engine,
Fuel control ff1H that generates the air-fuel mixture supplied to the engine
and an electric circuit coupling the concentration detection device to the fuel metering device so as to feedback control the air-fuel ratio of the mixture to a set value in response to an output signal of the concentration detection device. The air-fuel ratio control device for the air-fuel mixture supplied to
Publication No. 955).

Figure 2 is a complete diagram of the air/fuel pressure control system (2D headset) as described above.

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 a fuel passage 5,6 that communicates the float 4 with the primary intake passage, and these passages are connected to an air-fuel ratio control valve 9 via air passages 3a and 3b, respectively. .

Generally speaking, the carburetor 3 is formed with oblique passages 7a and 7b that communicate the float 4 with 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 3 of the secondary intake 1ffl passage.
The frontage is slightly upstream of 0b.

Further, the passage 7b has an air passage 8d having a fixed throttle.
It communicates with the inside of the air cleaner through.

In the illustrated example, the control valve 9 consists of three flow rate control valves,
The multi-flow m fill 12fl valve includes a cylinder 10, a valve body 11 displaceably inserted into the yielding cylinder 10, and a coil spring mounted between the cylinder and the valve body to press each valve body in one direction. It is made up of 12.

The non-coil 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 10 of the cylinder 10 through which the valve body taper portion 11a is inserted
The opening area of a is changed.

One end (the end on the opposite coil spring side) of each valve body "11 is attached to a worm member 17I which is prevented from rotating so that it can reciprocate.
! The connecting plates 15 are in contact with each other.

The worm member 14 is threadedly engaged with a rotor 17 of a stepper motor 13, which is rotatably arranged around the radial bearing 16. Further, a solenoid 18 serving as a stator is arranged around the outer periphery of the rotor 17.

The solenoid 18 is an electronic control unit (r
It is electrically connected to EcUJ>20.

When the solenoid 18 is actuated by a drive pulse from the ECL1 20, the rotor 17 rotates, and the worm member 14, which is engaged with the rotor 17, 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 fixed housing 21 of the stepper motor 13 is provided with a permanent magnet 22 and a reed switch 23 facing 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, the shielding plate 24 is displaced from side to side as the plate 15 is displaced from side to side.

And even more, this! At 112, the reed switch 23 is controlled to turn on and off.

In other words, the empty ratio νIf211 valve body/metal of valve 9, permanent [
When the four stones 22, the reed switch 23, and the shielding plate 24 pass through the daylight position determined by the mounting position 2, the reed switch 23 is turned on or off depending on the direction of movement.

The reed switch 23 supplies a binary signal corresponding to this on/off switching to the ECU 20 (It).

Note that the housing 21 has an air intake port 2 that communicates with the atmosphere.
5 is formed, and the filter 2 is also inserted into this intake port 25.
6, the atmosphere is led to each flow control valve.

On the other hand, an 02 sensor 28 made of zirconium oxide or the like is provided on the inner wall of the exhaust manifold 27 of the engine and protrudes into the manifold 27, and its output i! E C
Supplied to U20.

Further, an atmospheric pressure sensor 29 is arranged to be able to detect the atmospheric pressure around the vehicle in which the engine is mounted. The atmospheric pressure sensor 2
The detection value signal No. 9 is also supplied to the ECU 20.

Further, a thermistor 33 is installed in the circumferential wall of the engine cylinder filled with engine cooling water to detect the cooling water temperature representative of the engine temperature. The detection value signal of the thermi reflector 33 is also supplied to the ECU 20.

In addition, in FIG. 2, the reference numeral 39 indicates Co in the exhaust gas,
A ternary melting medium 31 for purifying HC and NOX detects the intake pressure in the intake manifold 2 downstream from the throttle valve +J O" +30b via a pipe line 32, and sends its output to the ECU.
20 is a pressure sensor, 35 is an engine rotation speed sensor, and 37 is an ignition switch.

Next, the content of the conventional air/fuel compression control described above will be explained with reference to FIG. 2.

First, when the ignition switch 37 is turned on when starting the engine, the ECU 20 is initialized. Thereafter, the ECU 20 detects the N n': (1 position) of the stepper motor 13, which is an actuator, via the reed switch 23.

Note that the reference position is detected based on the position when the reed switch 23 of the stepper motor 13 is turned on or off.

Next, the ECU 20 drives the stepper motor 13 from the reference position to a predetermined position (preset position) (hereinafter referred to as IF) ScrJ suitable for starting the engine, and sets the initial air-fuel ratio to a predetermined value (: set.

However, especially at a cold start, a rich air-fuel mixture (low air-fuel ratio) is required, so as is well known, choke or pie-stark (not shown)
Air-fuel ratio correction means such as these are provided, and these allow for excellent starting and warm-up operation depending on the outside temperature and engine heat conditions. 1IIIS D has been done.

δ, this choke is dangerous starter, manually air :j
) or control the fuel, and there are 2D types that automatically control them in response to engine temperature, for example.

Next, the ECU 20 monitors the activation state of the 02 sensor 28 and the engine cooling*temperature Tw detected by the thermistor 33, and determines whether the start condition for empty-air ratio control is satisfied.

In order to perform air-fuel ratio feedback control on the iE l1ir, two conditions are satisfied: the 110z sensor 28 has risen sufficiently in temperature and is activated, and the 2 engines have completed warming up. It is necessary.

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

When a current is supplied to the 02 sensor with such characteristics from a constant voltage source built into the ECU 20 through a resistor having an appropriate resistance value, the output voltage changes to the voltage of the constant voltage source (for example, 5 volts), and the output voltage decreases as its temperature increases.

Therefore, in a world where an activation signal is generated when the output voltage of the 02 sensor drops to a predetermined voltage VX, and a predetermined period of time (for example, one minute) has elapsed since the signal was generated,
In addition, the cooling water temperature T is adjusted to a predetermined value such that the automatic choke opens to the opening degree that allows air-fuel ratio feedback υ1go.
After confirming that W has increased, air-fuel ratio feedback control is started.

Note that the stepper motor 13 is moved to the predetermined position p3 during the 02 sensor activation and cooling water temperature TV detection stage.
It is held in cr.

When the above-mentioned control at the time of starting is completed, the process shifts to basic air-fuel ratio control.

That is, the ECU 20 responds to 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, and the atmospheric pressure P△ from the atmospheric pressure sensor 29. Then, the stepper motor 13 is driven to a predetermined position, and the air-fuel ratio is set to a predetermined value.

More specifically, this basic air-fuel ratio control includes (1) each oven loop L'l i2'I1. when the throttle valve is fully open, (2) idling, and (a deceleration), and (4) partial valve load. It consists of a closed-loop control 20. All these controls are performed after the engine has warmed up.

First, the four conditions for the 1-Bunrobe control when the throttle valve is fully opened are the gauge pressure difference (PA) between the absolute pressure PB detected by the pressure sensor 31 and the atmospheric pressure (absolute pressure) PA detected by the atmospheric pressure sensor 29. -PB) is lower than a predetermined difference ΔP.

The ECU 20 compares the difference between the output signals of the sensors 29 and 31 with a predetermined difference ΔP stored therein.

When the above conditions are met, the stepper motor 13 is moved to the oven hole 11 facing the throttle valve U port.
A predetermined air-fuel ratio (preset position) that provides the optimum air-fuel ratio for engine emissions when the engine is turned off under 20 conditions.
It is driven until it reaches p3wot and stopped at the predetermined position.

Note that when the throttle valve is fully opened, a known economizer (not shown) operates, and a rich air-fuel mixture (with a low air-fuel ratio) is supplied to the engine.

The oven loop control condition during idle is such that the engine speed Ne is a predetermined idle speed N 1dl (for example, 10
This holds true when it is lower than 1000ro.

The ECIJ20 receives the output signal Ne of the rotation speed sensor 35,
The stepper motor 1
3 is driven until it reaches a predetermined idle usage (preset position) PSicll that is optimal for engine emissions, and is stopped at the predetermined position.

Next, the oven loop f, II condition during deceleration is such that the absolute ffPB in the intake manifold is a predetermined absolute pressure P B
This holds true when it is lower than dcc.

The ECU 20 compares the output signal PB of the pressure sensor 31 with a predetermined absolute pressure pB+jec stored therein, and when the above-mentioned conditions are satisfied (3, stepper motor 13
The problem with the above-mentioned oven loop control conditions during deceleration is that the absolute pressure PB in the intake manifold is increased by deceleration. When the value decreases below a predetermined value, the exhaust gas-derived -C (hydrocarbon) increases, and as a result, the depletion feedback 1 level based on the detection value signal of the 02 sensor cannot be accurately performed, and the mixture theory The mixture ratio or fuel ratio is not q.

Therefore, as described above, the absolute pressure P[3 in the intake manifold detected by the pressure sensor 31 is equal to the predetermined value P
8 dec, move the actuator (stepper motor) to a predetermined step (preset position) PS dec that provides the optimum ratio for engine emissions when the A-bun Lube 2ill 1 condition during deceleration disappears. Oven loop control; made it possible to commit 11 sins.

Note that the atmospheric pressure P△
Depending on the respective stepper motor 13 door 1!
7i:1Qif7PSWOj, PSidl,
It is desirable that PSdec4j be properly modified.

On the other hand, the closed-loop control condition at partial load is satisfied when the engine is in a bad operating state other than when each oven loop t11 control condition described above is satisfied.

In this closed loop 1ilII2II, EC
U201, the engine rotation B2 Ne detected by the rotation speed sensor 35 and the output signal V of the 02 sensor 28
Proportional control by feedback (1 step below)
P]0 control) or integral control (hereinafter referred to as "l peak control i
(referred to as J).

7. At t1llll, if the output voltage of the 02 sensor 28 changes only on the Hatake level side or lower level side than the predetermined voltage Vrer (ID corresponding to the theoretical mixture ratio or air-fuel ratio), Paragraph 1 II M Execute.

That is, the output voltage of the 02 sensor is equal to the predetermined voltage Vref
, the position of the stepper motor 13 is corrected according to the integrated value of the 21 direct signal corresponding to being on the high level side or the low level side, and a stable and accurate position υI is obtained.
Perform tIl.

On the other hand, when the output signal of the 02 sensor 28 changes from a high level side to a low level side, or conversely from a low level side to a high level side, P 1n a+lI ? Run JD. That is, the position of the stepper motor 13 is corrected in accordance with a value directly proportional to a change in the output voltage of the 02 sensor, and control is performed more quickly and efficiently than the 111i control.

In the one-term control shown in (e) above, the position of the stepper motor is changed according to the signal obtained by integrating the binary signal based on the change in the output voltage of the 02 sensor, but the position of the stepper motor is changed every second.
The number of steps to be reduced is changed depending on the engine rotation.

g per second due to one-term control in the low rotation range! ! ! ! Although the number of steps to be lost is small, it increases according to the upper limit of the rotation speed, and the number of steps per second in the rotation speed is controlled to be large. - Also, the predetermined voltage V
Regarding rer, 02 from s level side to low level side
In P control, which is performed when there is a change in the sensor output or a change in the opposite direction, the number of steps of the stepper motor that increases or decreases per second is always the same predetermined number, regardless of the engine speed. 11I! (for example, 6 steps).

Roughly speaking, the engine zero start-air ratio during acceleration is 11 υ
p ta, when the engine t'7f m is completed and the engine speed Ne shifts from the low speed range to the high speed range, this is done on the condition that the above-mentioned predetermined idle speed ThN1dl (for example, 1000rc+m>) has been exceeded. It will be done.

When this condition is satisfied, the ECU 20 moves the stepper motor 13 to a predetermined acceleration position (preset position 1W).
) Rapid transition to PSacc. Immediately after this, EC
U20 starts the aforementioned 7 fuel ratio feedback control.

As described above, during zero start-acceleration of the engine, the actuator position is shifted to a predetermined preset position PSaCC with less harmful gas emissions.

Therefore, in so-called zero start, in which a vehicle with a red engine is accelerated from a stopped position, this is advantageous in terms of exhaust gas countermeasures, and the subsequent air-fuel ratio feedback can be performed satisfactorily.

The switching of the zero motor during the transition from the various oven loop controls 2 (l to the closed loop i, lI mode at partial load, or vice versa) described above is performed as follows.

First, when switching from a closed loop to an oven loop, the ECU 20 sets various preset positions PScr during the oven loop described above, regardless of the position of the stepper motor 13 immediately before entering each oven loop state.
, PSwot, p3idl.

Stepper motor 13 is rapidly moved to p 3 dec or PSacc (corrected for atmospheric pressure if necessary). This makes it possible to immediately start oven loop control depending on the poor operating condition of each engine.

On the other hand, when switching from the oven loop to the closed loop, the stepper motor 13 starts air-fuel ratio feedback control in the 1-term mode in response to a command from the ECU 20.

The reason for this is that the timing at which the output signal level of the 02 sensor changes 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. , by P-term control, empty (ratio fee j: high Iri: l'l ”: Illri Gel, fetus goro 4[: compared to the one-term system i3D + complicated noi i-bank control When starting up, it is possible to make the position of the straight stepper motors 1 and 2, which are operated in a closed loop, smaller.
It depends on whether the high emission stability or high emission stability will be achieved in the early stage.

Note that the stepper motor used as an actuator for the air-fuel ratio control valve 9]3's z position is monitored by a position counter (up-down counter) in the FCLj20, but this Due to disturbance, there may be a discrepancy between the contents of the counter and the actual position of the stepper motor.

In such a case, the ECU 20 operates by regarding the non-count value on the counter as the actual position of the stepper motor 13. In control, it interferes with control operations.

Therefore, in the air-fuel ratio control system shown in FIG.
5 positions (for example, 50 steps) and at the same time preset the reference position step instruction (for example, 50 steps) stored in the ECU 20 in the position counter, thereby ensuring the subsequent control t2DvJ degree. .

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

As mentioned above, conventionally, at the time of starting, after the stepper motor 13, which is an actuator, is moved to the stomach position NtI', the stepper motor 13 is driven to a predetermined position ipscr suitable for the fetal movement of the engine. , first ff172
”!I set the ratio to the specified chain and watched as Dan 1 was completed.

In addition, a two-combustion 7111 positive means such as a choke or pie-stark was provided to ensure good starting and warm-up operation depending on the outside temperature and the condition of the first stage of the engine.

However, the air-fuel ratio correction means based on the choke and pie starter 1 is 1. It is a bimetal that responds to one arm such as the engine temperature, and uses the thermal expansion of the aluminum alloy to control the engine. Therefore, there was a drawback that the optimum air-fuel ratio characteristics of the engine could not be maintained over the entire warm state.

The present invention solves the problems of (1) and (2). It is what was done.

(Means and operations for solving the problem) In order to solve the above problem, the present invention provides that the warm temperature during fetal movement is increased by the engine temperature in the 1-field [correspondingly, By moving the setting lever of the stepper motor 13, which is used as an actuator for the ratio control valve 9, in conjunction with the air-fuel ratio correction means such as the above-mentioned jocks and pistons, optimum engine performance can be achieved throughout the warm-up state. Sky f! ! It is characterized by a 41° 11 angle angle which improves its stopping characteristics.

(Example) 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 reference numerals as in FIG. 2 represent 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 controller 3. be done.

The computer section 200 may be of a well-known type, and may include a CPU 20.
1. Common bus 2 for RA, M2O3, ROM 203 ti; and data and instruction transfer between them.
Consists of 07.

02 sensor 28, TW sensor 33, Netn) J-35
and the lower H sensor 208 that detects the angle of the throttle valve.
Each detection output, such as , is supplied to the computer section 200 via the input interface 202 .

Further, FIG. 3 is a functional block diagram for explaining the present invention in detail.

In FIG. 3, the sampling hold/Δ/D conversion circuit 210 samples the analog output from the TW sensor 33 in the first scheduled sampling cycle, holds this as the current engine temperature value, and converts it into a digital value. do. The digitized current engine temperature value TW is sent to the comparator 22.
0 and is supplied to the engine operating state determination circuit 242.

Note that the TW sensor 33 is connected to an even switch 37.
At the beginning of startup when the engine is turned on, the engine is in a transient state, that is, a state in which the engine temperature cannot be accurately detected.

Therefore, the sampling hold/A/D conversion circuit 2
10 is a period of time (not including sampling of the J sensor signal) until the scheduled time (for example, 1 to 2 seconds) passes from the start and the TW sensor 33 reaches a steady state (a state in which one engine cycle can be accurately verified). It is desirable to do so.

In addition, to determine whether the TW sensor 33 has reached a steady state, determine the absolute time of the difference between the previous sampling value of the TW sensor 33 and the current sampling value, and the maximum value of the same absolute value when the sensor is in a steady state. It can be detected by comparing. In other words, if the previous winter becomes smaller than the latter, it can be said to be in a steady state.Therefore, when using this method, the sensor signal from the time when the steady state is confirmed is transferred to the sampling hold/A/D conversion circuit. 210 can be sampled.

Warming complete = lv+w register 218 is the warming complete temperature value T for determining that the engine is in the warming completed state.
Remember S.

The comparator 220 compares the current engine temperature value TW with the [lI-specific completion temperature supply TS], and determines if the current engine temperature value W is smaller than the warm-up completion temperature value TS. As it is not, a warm mud-like formation occurs.

Then, the warm state and the hot state are supplied to the engine operating state determination circuit 242. Made by engine! 1] The condition determination circuit 242 receives the warm-up condition signal and determines the stepper motor 13 as a function corresponding to the current engine temperature value TW.
The basis of i% or l, 1 E] t'j down purchase No. 16 is leveled (
Target) (Set Cera 1 to q on the disc 244.

By the way, an example of the characteristics of this reference (eye (=) position) (No. 8) is as shown in FIG. 4 or FIG. 5.

That is, when the current engine temperature value TW goes up to the start (R1, 4), the position (preset position) of the stepper motor 13 changes as shown in FIG. 1iIll linearly from rich to lean
It has a characteristic that makes it easy to use.

Further, in FIG. 5, as will be described later, the position (preset position) of the stepper motor 13 has such a characteristic that the fuel R is controlled stepwise from rich to lean.

T W 1 in Figure d5.7A4 and Figure 5 indicates the temperature value at which the heating is completed. Therefore, the current engine temperature (
When the direct TW becomes TWl, it is assumed that the warming has been completed and the warming state signal disappears.

However, without setting the warm-up completion temperature to a fixed value, start nt.
If the temperature is gradually increased as the ambient temperature of the engine decreases in step 7, the warm state signal can be maintained for a long period of time during a cold start, etc.
42, so it is necessary and sufficient.
ffi will now be performed.

In addition, based on (target) the 1j nature of the power supply system, the purpose of this light is an air-fuel ratio correction means such as a choke or pie starter.
The optimal air-fuel ratio characteristic of the engine is to compensate for the shortcomings of the EM 1M state, and by supplementing the characteristics of the choke and starter, It is desirable to set the optimum air-fuel ratio characteristics of the engine over the entire 1'3 state.

As is well known, the stepper motor 13 is driven by the pulse output from the stepper motor drive pulse supply circuit 246 via the driver 206, and its current position is represented by the count value of the up/down counter 250. .

A comparator 248 compares the up/down counter 2500 count with the value stored in the reference (target) position register 244 to make them equal.

The control signal is used to drive the stepper motor (j pulse supply circuit 2
46.

In response to this, the stepper motor drive pulse t8
The circuit 246 generates a pulse to drive the stepper motor 13 in the forward or reverse direction, driving the stepper motor 13 to a position corresponding to the value set in the i$ (target) position register 244. .

That is, during warm-up, the stepper motor 13 changes the air-fuel ratio from rich to rich, linearly or stepwise, according to the characteristics of the reference (target) position signal shown in FIG. 4 or 5. Eli will be completed while being moved.

After the top 1 is completed, as will be described later, the position of the stepper motor 13 is controlled by the oven loop or feedback, which is determined according to the new engine operating condition at that time. An appropriate two-fuel ratio is actually achieved depending on the operating condition.

Next, with reference to the ↑-tota in Figure 6, '? S1
The operation of determining the preset value according to the embodiment of the present invention shown in the figure will be described in detail.

Note that this FIG.
t: This is a detailed description of the processing performed at t.

Step 51301 -- The TW sensor signal which is the output of the TW sensor 33 is read and stored as the current engine temperature 1st shift TW.

As described above, the TW sensor 33 is in a transient state when the ignition switch 37 is first turned on, and is therefore unable to detect the carrot temperature at the correct bff. Therefore, this =1 value is I until the scheduled time has passed and the TW Senki 133 is in a steady state.
It is best to avoid starting 71.

In addition, as described above, it can be detected by comparing the absolute value of the previous sampling value and the current sampling value of the TW sensor 33 with the maximum absolute value of the same (number) in the steady state of the sensor. In other words, if the former value becomes smaller than the above value, it is a steady state, so even if you start reading from this time, you can read an accurate engine temperature value.

Step 51302: It is determined whether the current engine temperature value TW stored in the previous step 51301 is lower than the pre-stored engine temperature + ITS. If it is equal to or greater than TS, it is assumed that the warm-up has been completed and the process proceeds to step 51305.

In addition, as mentioned above, this warm-up completion temperature value is not used as a fixed decoy; It is desirable that the temperature increase gradually as the ambient temperature of the engine decreases at 71:00, so that necessary and sufficient warm-up can be performed during cold fetal movements.

When the engine is initially started, the current engine temperature (i T W is lower than the warm-up completion temperature I\ITS, so it is assumed that the engine is being warmed up and the process proceeds to step 51303.

Step 51303: Set the warming up flag.

Step 51304...The current engine temperature that was exceeded in step 31301 (according to the direct TW 74, the preset temperature of the stepper motor 13 is predetermined from 1 to 74, as explained with reference to FIGS. 4 and 5). A preset value of the reference (target) position register 244 corresponding to V is selected (eg, read from a table) and stored.

That is, the preset position of the stepper motor 13 according to the current engine temperature value TW is determined and described. The process then returns to the main program.

Step 51305...In step 51302, the current engine temperature value TW is changed to the one-flash completion temperature value TS.
If it is determined that the above is the case, as described above, the processing is
The process advances to step S1305. In step 51305, the warm-up flag set in step 51303 is reset, and a warm-up completion flag is set.

Then return to the main program.

The oven loop preset value setting operation according to the embodiment of the present invention shown in FIG. 1 will be described in detail with reference to the flowchart in FIG. 7.

By the way, this figure 7 shows step S41 in figure 8 which will be described later.
This figure shows in detail the processing carried out in the figure.

Step 54101...Step S in FIG. 8, which will be described later
At step 17, it is determined whether the flag indicating the current engine operating state is a warm-up flag. Qtr+
If the flutter flag is set in 3, it is assumed that an oven loop control other than 81 m has been selected, and the process advances to step S4103.

If the warm-up flag is set, step 3
Proceed to 4102.

Step 34102...Step S1 in FIG. 6 above
At step 304, the preset 1iTi is read out and set in the register 244 at position C. Thereafter, the program returns to the main program.

Step 54103...Step S in FIG. 8, which will be described later
The predetermined stepper motor 1 is
Select a preset value of the reference (target) position register 244 corresponding to the preset position of No. 3 (for example, read from a table), and select the preset value of the reference (target) position register 244 corresponding to the preset position of 3. (Target) Set in position register 244.

Note that this preset value may be one fixed position that is common to all engine operating conditions that perform the oven loop except for heating. .

Then return to the main program.

Figure 8 shows the internal combustion engine to which the present invention is applied.
! 2 is a flowchart illustrating the overall aill operation of Suburban 2. Hey, this l, II U-Ten movement.
The ECU having the configuration shown in FIG. 1 can actually achieve 1''T.

Step 511: When the ignition switch 37 is turned on, the ECU 20 is first initialized using a known method.

Step S12... The current throttle opening 11ff is read, and its open/closed state and opening range are determined.

At the same time, it is determined whether the engine is in an accelerating state. When in an acceleration state, an acceleration flag is set, and an acceleration holding flag is set for a scheduled time after the end of acceleration.

Step S13...Read the output of the TW sensor 33,
As previously detailed, when the engine temperature is warm (lower than the τ completion temperature value), the reference (target) position register 244, which corresponds to the preset position of the stepper motor 13 according to the engine temperature, is Determine the bullet value and memorize it.Roughly, turn off the warm-up flag.

On the other hand, as is clear from the previous explanation, if the engine temperature is equal to or higher than the completion temperature value, it is assumed that the warming has been completed. Set.

Step S14...02 Tl of whether the sensor 28 is active or not! make the determination. As described in the previous section (1), in order to accurately perform feedback control of the second loss ratio, it is necessary that the 02 sensor 28 be sufficiently activated.

Moreover, the activation can be determined by comparing the output voltage of the 02 sensor 28 with a reference value. If it is confirmed that the 02 sensor 28 is sufficiently activated, the activation flag of the 02 sensor 28 is set.

As is well known, the output of the step S15...02 sensor 28 is approximately lean (
It becomes low on the thin (thin) side, and high on the rich (7) side. In this step, it is determined whether the air-fuel mixture is on the lean side or the rich side based on the output characteristics of the ○2j7 sensor 28, and roughly the output changes from the lean side to the rich side. Also: Determine whether the image has been reversed and set the respective flags.

Step S16: It is determined whether the power supply voltage VB of the ECU 20 is within a specified range. stepper motor 1
3 is positive 5 if the power supply voltages V and B are equal to or higher than the specified value 51.
K does the manual work. In other words, it is unlikely to make a sad tone or make strange movements due to external forces, and it is possible to accurately control the position.

However, when the power supply voltage VB becomes lower than the lower limit value E2, the stepper motor 3 starts to be preloaded irregularly by an external force, regardless of the pulse application to the solenoid 18, which makes it difficult to use the positive 1iTr; The html framework will be created.

In addition, the core voltage VB is between the specified value E1 and the lower limit (direct E2).
Between 8 and 8, there is a risk that the stepper motor 13 will be moved irregularly by an external force.
There is a possibility that the amount of rotation will not correspond accurately to the amount of rotation.

Therefore, when the Tl power supply voltage regulation (DC is lower than E1), the exact position of the stepper motor 13 iI'I 120
(feedback t(I l and oven loop system (
7) 1) is not maintained and the power supply voltage reaches the γ limit t1a.
When the position is lower than E2, the accurate correspondence between the actual tlH of the stepper motor 13 and the count value of the up/down counter 250 (FIG. 3) which should represent the position cannot be maintained.゛In this step S16, it is determined in which region the values of electric π and field pressure are located, and respective flags are set.

Step S17: Processing in each step described so far: Based on the states of various flags, - r5 and the result (flag) of engine rotation yj range determination, which will be described later with respect to FIG. Is Jin's work force state and its operating state feedback? J11φ11th death again (
Determine which area is outside the oven loop control area,
Set each flag.

The operating states of the engine include stop, start, warm-up, hot restart, idling, zero-start acceleration, deceleration, acceleration, and high speed (throttle valve fully open).

In addition, in this step 517, it is best to memorize both the currently detected operating state and the previous operating state detected immediately before, as well as their respective control modes (feedback control or oven loop control). be.

Step 818... actuator (i.e. second
Stepper motor 13 and connection plate 15 shown in the figure
) has been initialized. This determination is made by referring to an actuator initialized flag provided within the ECU 20.

If initialization is not completed, step S19
Proceed to. In addition, immediately after turning on the ignition switch 37, and when the power supply voltage drops below the lower limit value E2,
This judgment does not hold true for 4u Nycle.

Step S19: Determine whether the initial processing Jψ flag is set. Since it is not set at first, the process advances to step S20. When the determination is true, step S20 is repeated and step S21 is performed.
You will be able to proceed to

Step S20...actuator, Zunawara, stepper motor 13 and iIr! Set the knot rate 15 position.

- As the reference position, it is preferable to adopt a position where the stepper motor 13 is fully driven to the right or left end in FIG. 2. In the example of FIG. 4, this corresponds to setting the reference (target) position register 244 to, for example, "O''.

At the same time, the up/down counter 250 is set to a value corresponding to the opposite end, such as "'100". After that, a flag indicating that initial processing is in progress is set.

Step 321...The count value of the up/down counter 250 representing the current position of the stepper motor 13 (for example, '100') is a value corresponding to the reference position (the memorandum value of the reference (target) position register 244). In the present example, it is determined whether it is equal to ``Opa).

At first, this judgment does not hold, so the process i3 step S
Proceed to 22. If the determination becomes true, the 9B process proceeds to step 324.

Step S22... It is determined whether the flag indicating that the power supply voltage is lower than the specified value E1 is set in the previous step S16.

When the flag is set, there is a possibility that accurate position control fl1 (initial ff1y1) of actuators such as the stepper motor 13 cannot be performed, so the process returns to step 312 without doing anything. If the flag is not set, step 823
Proceed to.

Step S23...Drives an actuator such as the stepper motor 13 in the direction of the position p4 set in step S20, and increases the count value of the up/down counter by +1.
, or -1. In other words, in the present example, the count value of the up/down counter 250 is decreased by 1.
, drives the stepper motor 13, and simultaneously increments the up/down counter 250 by 1.

After that, the process returns to step 812, and thereafter, steps S12 to S23 are performed until the determination in step S21 is established.
cycle. However, in this case, since the determination in step S19 is established, the process in step S20 is omitted.

Every time the loop of steps 312 to 23 is circulated as shown in #iix, the stepper motor 13t is driven toward the reference position by 11 steps, so it finally reaches step S.
21 comes to hold true.

In this case, the actual position of the stepper motor 3 when initial processing is started is a reference number.Assuming that the stepper motor 13 is at one end of movable σ0 in FIG. The number of pulses necessary to drive the stepper motor 13 to the end reference position 2 will be supplied to the solenoid 18 during the cycle of steps 812-23.

Therefore, in general, according to this initial individual method, after the stepper motor 13 reaches the reference position, an extra drive pulse is supplied to the nlenoid.
In this state, since the movement of the stepper motor 13 is mechanically blocked, it will not be driven beyond the reference position, and the stepper motor 13 is completely set at the reference position, and the initial of the actuator is It's finished.

Step 324: The actuator initialization processing flag is reset, and at the same time, the actuator initialization completed flag is set.

Step 530: In the previous step S17, it is determined whether the current l1i11σ0 mode is feedback control, that is, whether the feedback control flag is set. When the flag is set, the process proceeds to step S51 to perform feedback IL control, and when it is not set, the process proceeds to step S41 to perform oven loop control.
to) Mr.

Step S41: As described in detail previously, a standard corresponding to the preset f device of the stepper motor 13 is determined in advance in response to the current engine operating condition (bad flag) set in the previous step 317. A preset value of the (target) position register 244 is selected (for example, read from a table) and set in the reference (target) position register 244.

However, if the current engine operating state is the CL state, as is clear from the previous explanation, step S1
3, the stored brilet value 8 is read out, and this is set in the reference (target) position register 244.

Step S42... Determine whether the count box of the up/down counter 250 (i.e., the current bar of the stepper motor 13) is equal to the preset Mi set in the previous step. If they are equal, return to step 312,
If they are not equal, the process advances to step S/13.

Step S43: Repeat step S22 and the level determination of the spy voltage.

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

By repeating the processes of steps 341 to 44 described above, the actuator is driven to the position corresponding to the preset value set in step 841.

Step 551: In the previous step S17, it is determined whether or not the feed park flag was set as the bamboo time 1TIII2ft mode. If the determination is not established, the process proceeds to step 352, and if the p1 constant is established, the process proceeds to step S53.

Step S52... Feedback control/shift (use) Depending on which region (see Fig. 10) the engine operating state before was in, the 1Z predetermined transient (determined ) drive the stepper motor 13 to the position.

The processing content in this step is virtually the same as that of the steps 541 to 44 described earlier, except that the preset position n of the stepper motor 13, that is, the position t = position 4 is in phase j. A detailed explanation will be omitted.

When the count value of the up/down counter 250 representing the position of the stepper motor 13 becomes equal to the stored content of the reference (target) position register 244 representing the transient position, it is assumed that the transient position setting is completed and step S is performed.
Return to 12.

Note that this step S52 is provided to quickly and smoothly transition from oven loop control to feedback control, and is not necessarily necessary and can be omitted. When this step is omitted, the previous step S51 is also unnecessary.

Step S53... From the standard time/frequency division ratio table (an example of which is shown in FIG. 11, which will be explained later), it is determined in advance as a function of the elapsed time from the time when the output of the 02 sensor is reversed. Extract the basic frequency division: F-DOti. Next, the basic frequency division fD is determined by the engine temperature lower W determined in the previous step, the slot 11111 degree value, and the engine rotational speed region which is increased by +1 by the process of FIG.

Correct and calculate the frequency division ratio a.

Alternatively, a number of time/frequency division ratio tables corresponding to various combinations of these parameters may be prepared using the engine temperature TW, throttle stratification, and engine speed region 1 steepness as parameters. Depending on the combination of engine parameters, certain
It is also possible to select a frequency division ratio table and obtain the frequency division ratio based on this.

d3, at the stage when the process first moves to this step S53, the elapsed time from the time when the output of the 02 sensor is reversed is not controlled unless a means such as a counter is specially prepared to measure this at r1. Since this is not possible, a preset value predetermined as the elapsed rf interval is used, and based on this, the basic frequency division ratio D○ of the previous step (e) is calculated, and feedback control is started.

On the other hand, it is determined whether the status flag of the 02 sensor 28 obtained in step S15 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 direction in which the air-fuel mixture approaches the stoichiometric air-fuel ratio) is determined. direction).

Step 854: The power supply voltage range is determined in the same manner as in step S22 described above.

Step 355...According to the frequency division height, the ECU2
It is determined whether or not the process No. 0 has passed through the branches of steps 853 to 55 D times, and at the Dth time, the stepper motor 13 is driven by one step in the direction specified in the previous step S53. This brings the air-fuel ratio of the air-fuel mixture close to the stoichiometric ratio.

In addition, in the flowchart of FIG. 8, step 31
The actuate initial cell processes 9 to 24 are not necessarily necessary when performing feedback control. Therefore, the processing steps of steps 318 to S24 may be performed between steps S30 and 341.

FIG. 9 is a flowchart showing the engine rotation speed range determination procedure.

Step S71: When an engine pulse is generated by the Ne sensor 35, this interrupts the computer unit 200, reads the count value of the 1-interrupt period counter, and resets the counter.

Alternatively, the engine rotation period can also be determined by reading the clock timer and calculating the difference from the previous reading by 8 points.

Step S72: Based on the rotation period obtained as described above, the rotation speed range of the engine is determined. The above engine rotational speed range is determined, for example, as shown in FIG. 10.

In Fig. 10, the horizontal '1th is the engine speed Ne(
1, which is the reciprocal of the rotation period), and the vertical axis is the throttle opening value lower H.

In this figure, the engine rotation speed range is divided into five regions with rotation speeds N1 to N4 as boundaries 1a, and further divided into two regions υj based on the inter-throttle equivalent value TH. As a result, the engine operating range is divided into 10 ranges (
It is divided into 1) to (10).

As can be easily understood from the figure, areas (1) and (2)
) is the start/idle area, (3) is the deceleration area, (/'I
) are high speed regions, and when the engine operating condition bottoms out in these regions, oven loop control (2p) is performed.

Matoko, the rest of ff1lii! (5) to (10) are normal cruise ranges, and when the engine operating condition falls into one of these ranges, the acceleration state is poor or the acceleration is maintained and the T
Feedback control is performed unless otherwise specified.

Note that the apex of each arrow in FIG.
The engine operating point Uj corresponding to the transient (m-constant) position (see step S52 in FIG. 8) when moving to a certain point is shown.

FIG. 11(a) is a time chart that does not show the inverted state of the output of the 02 sensor 28, and FIG. 11(b) is a time chart showing the change in C12M of the stepper motor 13 for air-fuel ratio control.

When the output of the 02 sensor 28 is reversed, for example, from a rich side to a lean measurement, the stepper motor 13 is driven to the side that makes the air-fuel mixture rich.

In this case, immediately after the reversal, the stepper motor 13 is driven one step at each relatively small frequency division ratio (small clock count) C1, depending on the time elapsed since the reversal. The stepper motor 13 is driven one step every time C2.

Therefore, the stepper motor 13 is moved! ll speed is 0
Immediately after the output of the second sensor 28 is reversed, it is large, and gradually decreases as time passes. The relationship between the elapsed time and the corresponding frequency division ratio or clock count number is equal to 2, which is the time and time described above regarding step S53.
This is a frequency division ratio table.

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

During warming up, as the engine temperature rises, the fuel ratio
I'I The stepper used as the actuator for the I'I 79 can be controlled in the direction of α Aiki from rich to lean. By supplementing the ?2 ratio methods such as ?2, it is possible to obtain the optimum air-fuel ratio characteristics of the engine throughout the entire warm-up state.

As a result, it is possible to maintain the optimal air-fuel ratio characteristics of the engine throughout the entire range of warm conditions, and to maintain good efficiency in purifying harmful gases from exhaust gas during the warm-up period.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of a conventional air-fuel ratio υI display device 1lTI of an internal combustion engine, and Fig. 3 is a functional block diagram for explaining the +71 work of the present invention. Block diagram, Figures 4 and 5; Characteristic diagram showing an example of the correspondence between the engine temperature and the preset position of the stepper motor in Boshin; Figures 6 and 7 illustrate the main operations of the present invention. FIG. 8 is a flowchart for explaining the overall ill iD f) I fπ of the air-fuel ratio control device for an internal combustion engine to which the present invention is applied.
Figure 9 is a flowchart showing the procedure for determining the engine speed range, Figure 10 is a diagram showing an example of dividing the engine operating range based on the engine speed Ne and the throttle distance value TH, and Figure 11 (a). is a time chart showing the output reversal state of the 02 sensor, and (b) is the time chart showing the output reversal state of the 02 sensor.
3 is a time chart showing changes in the position of a stepper motor for. 13...Stepper motor, 20...ECU, 28...
...02 sensor, 33...TW sensor, 35...engine rotation speed sensor, 200...computer section, 2
06...Driver, 208...THt? Nsa, 21
0...Sampling hold/A/D conversion circuit, 21
8... Warnada completion temperature value register, 220... Comparator, 242... Engine operating state determination circuit, 244...
・Reference (target) blank register, 246...Stepper motor drive pulse supply circuit, 248...Comparator, 25
0...Up-down counter agent Michito Hiraki and 1 other person Figure 4 TWO Figure 5 TV/1 Figure 6 Figure 9 different figure 10 Figure τH

Claims (2)

[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 In an air-fuel ratio control device during warm-up of an internal combustion engine, the device includes a feedback control device that drives and controls the stepper motor so that the air-fuel ratio of the air-fuel mixture approaches a set value in accordance with an output signal of a detection device. a device that detects an engine temperature value at a sampling period; a device that outputs a warm-up state signal when the detected engine temperature value is below a warm-up completion temperature value; The stepper motor is characterized by comprising a device for storing a reference (target) position of the stepper motor, and a device for driving the stepper motor to the reference (target) position while the warm-up state signal is being output. Air-fuel ratio control device when warming up an internal combustion engine. (2) The warm-up completion temperature value is set to increase as the ambient temperature of the engine decreases. Fuel ratio control device.