JPS6095151A - Air-fuel ratio feedback control device - Google Patents

Abstract

PURPOSE:To improve the stability of an engine operation by providing a state discrimination device to find errors in an oxygen concentration detecting device and also by providin a time limiting device to stop feedback correction based on the integral processing in a control device. CONSTITUTION:An oxygen concentration detecting device 4 detects the concentration of an oxygen in the exhaust gas of an internal-combustion engine. A control command circuit 5 inputs the signals from the oxygen concentration detecting device 4, an exhaust gas thermometer 3, and a throttle opening detection switch 9 as well as the engine rotating speed signal; and judges whether the feedback control should be discontinued or not and then outputs the command signal to an air-fuel ratio control circuit 6 and a warning device 10. The air- fuel ratio control circuit 6 makes a feedback correction for the air-fuel ratio of a mixture generated by a carburetor 7. In this way, when there is any error in the output power of the oxygen concentration detecting device, the air-fuel ratio control circuit 6 discontinues the feedback control to prevent variations of the air-fuel ratio; thus the safety in the operation of the engine can be improved.

Description

[Detailed Description of the Invention] (+!Field of IT Industry Application) The present invention is an internal combustion engine, which detects the oxygen concentration contained in air gas and performs feedbank control of the air-fuel ratio of the intake air-fuel mixture. The present invention relates to a device that interrupts feedback control when the output of oxygen concentration detection means is abnormal.

(Top technology) Exhaust gas component measuring device (oxygen; stratification detector) in the engine exhaust system
By detecting the air-fuel ratio of the combustion mixture 'J' and applying feedback to the fuel metering device,
There is an air-fuel ratio control system that converges the air-fuel ratio to a predetermined value (see, for example, Japanese Patent Laid-Open No. 108429/1983).

(Problem that the invention is trying to solve) However, when performing such feedback control, the control (i, l, slope, da I2 (because it depends on the detection signal of the detector installed in the system) , this detection number 4M is 11-
When it is not normal, for example when the output value does not change for a predetermined period of time or more, the internal combustion engine's 11! It becomes difficult to adjust the fuel flow rate required for normal operation.

Therefore, in such a case, it is preferable to interrupt the feedback control in order to prevent the internal combustion engine from becoming unstable.

The present invention takes this point into consideration and determines an abnormal state by comparing and determining the output of the oxygen concentration detection means in the exhaust system, and when an abnormal state exists, interrupts the feedback control of the air-fuel ratio and restarts the engine. An object of the present invention is to provide an air-fuel ratio feedback control device 6 that prevents the operation of the air-fuel ratio from becoming unstable.

(Measures to Solve the Problems) Therefore, the present invention provides an oxygen concentration detection means for detecting the oxygen concentration in the exhaust gas of internal combustion, and a first detection value from the oxygen concentration detection means. In an air-fuel ratio feedback control device comprising an air-fuel ratio discriminating means for comparing and discriminating with a set value, and a control means for performing feedback correction on the air-fuel ratio of the air-fuel mixture by integrating the discriminant value from the air-fuel ratio discriminating means,
It has a second set value for determining abnormality in the output state of the oxygen concentration detection means in addition to the first set value, and this second set value
and a state determining means for comparing a set value of and a detected value from the oxygen concentration detecting means, and detecting the output state of the state determining means and performing an integration process in the control means when the output does not change continuously. The time limit f/stages for stopping the feedback correction based on the equation was increased.

(Function) Therefore, the output of the oxygen concentration detection p stage changes from 5°4 to 1'.
When the revised value of riS2 for 1 separation is exceeded and this state continues and does not change, the oxygen concentration detection means is set to 5 "4 Normal state 'l"! I 1tJisaJ,
Feedback control of the air-fuel ratio based on the output of the oxygen concentration detection means is interrupted. In addition, the air-fuel ratio of the mixture is controlled to a predetermined value based on the characteristics of the carburetor, etc., and the feed bank control continues in the normal state. The air-fuel ratio control will not be confused as would be the case when

(Example) Hereinafter, an example of the present invention will be explained based on the drawings.
The embodiment shown in the figure uses a vaporizer to
i+1) In the figure, 1 is the engine body,
2 is an exhaust pipe, 3 is an exhaust temperature meter installed in this exhaust pipe, and 4 is also a zirconia oxygen meter (oxygen concentration detection means), and this oxygen a14 detects the oxygen concentration in the exhaust gas and detects the combustion mixture. Measure the air/fuel ratio.

5 is a control command circuit, 6 is an air-fuel ratio control circuit having an integral function, 7 is a carburetor, 8 is a throttle valve, and 9 is a throttle level detection switch.

The control command circuit 5 receives signals from an oxygen meter 4, a temperature meter 3, a throttle angle detection switch 9, and a rotation speed (g).
The air-fuel ratio control circuit 6 and/or alarm device 1
Outputs a command signal to ().

As shown in FIG. 2, the zirconia oxygen meter 4 measures the air-fuel ratio (
This output No. 11 is input to the air-fuel ratio control circuit 6. As will be described later, this air-fuel ratio control circuit 6 compares the output of the oxygen meter 4 with a predetermined set value, and also performs feedback correction of the comparison judgment value to at least the non-integral Jjj L4rJ fuel ratio. Although not shown, the carburetor 7 is equipped with an electromagnetic on-off valve in the fuel passage or the air bleed passage, and these valves are turned on and off based on control signals from the air-fuel ratio control circuit 6 to correct and control the air-fuel ratio.

FIG. 3 shows an example of a military object of the control command circuit 5.

The control command circuit 5 includes an abnormality detection circuit 11 for the zirconia oxygen meter 4, an ant game that takes the AND of the output of the civilian rotation speed determination circuit 12 and the throttle discrimination signal from the throttle speed detection switch 9, and a thermometer. (if
f, even if the OR gate 15 outputs any of these 1-), it outputs feed bank control interruption No. 43 to the air-fuel ratio control circuit 6, or at 11.17 the same time, the output is output to the alarm device Pj I O. Output 11 motion command A3 bow.

Abnormality detection circuit 1 that determines the abnormal state of oxygen ffl' 4
1 detects when the time when the signal from oxygen ill 4 remains at the maximum or minimum and does not change exceeds a certain value 4R-
1) The output value of tf Noborigai 17, - Oxygen a) 4 is j(
11, or when the signal from the air ratio control circuit 6 is saturated due to the air-fuel mixture produced by the fuel metering device such as the carburetor 7 being too rich or lean (in Figure 1, the air-fuel ratio When the output voltage is 14 or more or 17 or more and there is little output change, etc., set the maximum or general minimum constant value of the output voltage in Figure 2 to 411141, otherwise there will be almost no change; It becomes impossible to accurately control the emptying ratio, and when such a situation occurs, it is better to stop the feedbank control and shift to normal fuel control (oven control) of the carburetor 7.

The abnormality detection circuit 11 interrupts such a state based on the output of the oxygen meter 4, and a specific example thereof is shown in FIG.

16 is a maximum value residence time detection circuit, and 17 is a minimum value stay time detection circuit.
(1: If; '7 interval detection circuit, l8 set time generation circuit, 1!] a, 191+ are comparators, 20 is an OR gate.

Then, the output in of oxygen d14 is input to the terminal 21,
When the maximum value remains, the nt+ detection circuit 16 has a set value for subtracting the maximum value of the output of the oxygen meter 4 by 1 as described above, and when the output of the oxygen meter 4 exceeds this set value. When the maximum value No. 411 is output, J is the small ship? 11 The 1-hour detection circuit 17 detects the minimum value of the output of the oxygen meter l [1! The minimum value signal is output when the output of lY2 elements r+l''[ is less than this set value.

This detection number 4H is inputted to the comparators 19a and 191, respectively, where it is compared with the revised time number (ij) input from the set time generation circuit 12 (1.1).
)], the detection signal (maximum value, minimum value) is stagnant l1
When the time is between 11 and 11, comparator 10a, I! An abnormality detection signal is output from lb.

In other words, the output signal from the set time generation circuit + 1i continues for a predetermined time, and is repeated at regular intervals, so the output from the acid 1 14 is the maximum or minimum value. 1. Keep the value unchanged for the set time. If there is no change, comparator 19a or 191] determines ORDATE 2 (
) is output as an abnormality detection signal.

Figure 75 (a) shows an embodiment of the nausea detection circuit 11, and Figure 5 (b) shows the output waveforms of each part. 23 input terminal r-22
By comparing it with the set value manually entered into the other node j of the comparator 23, the pulse is shaped into a two-dimensional pulse shape υ as shown in (b). Each time the pulse number 43 is input manually, the ridge counter 24 is switched from auxiliary to deactivated) or from j addition to addition operation. At the same time, the output 471 (d) of the oscillator 25 or a frequency generator (not shown) synchronized with the rotation of the engine is input to the clock terminal of the 1if reverse counter 24.

The inverse counter 24 uses the output signal (1) of the comparator 23 and the output signal (d) of the oscillation 'a'rF 25 to generate a carry signal (for example, if the vr inverse counter 24 is a 3-bit counter, then Outputs when the counter contents are in the I, J, I state during operation (No. 3) or borrow signal (same as when the counter contents are 0 when the counter subtracts,
(+, (Output in + state (No. 8) (C) is output., 2 carry f-1 or borrow 63-'
3' (c) is 7s.70. b2LE and person j+ 1
-1 This sets 7 lip 70 knob 26.

(Note that once the 7 rip 70 knob 26 is sent, it will remain in that state until the reset signal ([) is input, but the 7 rip 70 knob 26 will repeat the 7 rip and reset 7F every time the carry signal or borrow (R) is input.) ) The contents of the powerful number 24 can be changed to an intermediate value (e.g. 10 counts '(+'))
If there is B, preset it to 5 counts and use this ulf
Add or subtract 5 counts at the point, V: Then, AI・
1 to issue 2 111 or borrow signal (C)
reactor. )1. Do nipurisen 1.

Also, in Figure 2, in order for the total 4 continuous outputs to the acid and l to move by 1'11 between the maximum a and the minimum (), each human power of and date 27.2); Input 1 degree into one node j of Nl r, 70 knob; put the output ((・) into 2, and connect the output of comparator 23 11υ (
IJ) and this output (3s(1)) I, ? υ polarity inversion circuit 2! ``C inverted (f1 is input, ``?ndgegun 7, output from n8 can be used to change the state of oxygen meter 4 by 1!''). (,) is the air-fuel ratio control circuit 6 shown in FIG.
Alternatively, it becomes abnormality detection No. 4g for the alarm device 10.

Also, the signal (g>(
b> may operate a lamp, a buzzer, etc., but it is also possible to manually input these Iro (g) (1+) to OAG 1 (not shown) and use this as the above-mentioned abnormality detection signal.

Next, the Norconia oxygen meter 4 will not function properly if the ambient temperature is too low, so it is better to interrupt feedback control in such cases as well.
In the figure, the temperature is determined by the temperature determination circuit 13, and the oxygen meter 4
When the temperature reaches a temperature range where the operation becomes unstable, the signal from the temperature discrimination circuit 13 is outputted to the ORDATE 15.

However, even if this temperature limit is not used, if the output of oxygen ill 4 does not change, as described above, abnormality detection circuit 1
It is possible to determine whether the device is not functioning properly based on j.

Since the Norconia oxygen meter 4 does not detect unburned gas in the exhaust gas, it is desirable to interrupt the control even in such a case.

Therefore, an operation region in which a large amount of unburned gas is contained in the exhaust gas is deceleration operation (including engine braking).

In this state, the engine speed remains above a certain level, but the throttle valve is insufficient.

The rotational speed determination circuit 12 outputs a signal to the input terminal of the rotation (-)j of the AND gate 14 if the rotational speed is above a certain level by manually inputting No. 4. At this time, if the throttle valve 8 has a total of 1 fJ, the throttle I is fully closed (I is AND DATE), and the output is output to the input terminal of the 1st force of 4.

As a result, even though the engine speed is high, when decelerating with a small opening, an output signal of 1/1 is manually input to the OR gate 15.
5 outputs control interruption number 43...In each of the above cases, number 111 of ORDATE 15 is output,
As a result, the air-fuel ratio control circuit 6 interrupts control, or the alarm device 10 issues an alarm, and the carburetor 7 returns to normal control. Proportional control of fuel flow rate is performed.

When the interruption No. 43 ends, that is, the above-mentioned abnormal condition is resolved and the input (i4) of the OR gate 15 disappears, control is resumed.

By the way, when starting feed/back control, if a large empty ratio (III) is suddenly performed, the engine operability will drop to 1! + May be harmful.

In order to prevent this situation from occurring, it is desirable to set the air-fuel ratio correction parameter to zero when the control is restarted.

As a countermeasure against this, when the above-mentioned interruption signal occurs, the air-fuel ratio control circuit 6
By setting the integral gain of the integral circuit section to zero, it is possible to suppress rapid fluctuations in the air-fuel ratio when the control is restarted.An example of Ruruko's military body will be explained based on FIG. 6.

In the figure: 30 is the &i divider, 31 is the proportional amplifier 1.32 is the comparator, 33 is the adder, ;) 4 is the Nakata i signal written in 111, φl, and when it occurs, the contact 3411 closes and at the same time It is a switch circuit in which the contact 34b is turned on and off, and when it disappears, it performs the opposite actions (1) and (2).

The output of the oxygen meter 4 is inputted to a comparator 32, and the comparator 32 compares it with a predetermined set value, and the output of the comparator 32 is integrated by an integrator 30, and proportionally processed by a proportional amplifier 31. These outputs) are combined in adder 11 33 to provide air-fuel ratio feedback control No. 17.

In such a configuration, when the switch 34a closes due to the occurrence of interruption No. 111, the gain of the integrator 30 becomes zero, and the contact 34b of the proportional amplifier 31 opens and its output is added to the adder q. Therefore, when No. 17 disappears and the uplink feedback control starts, (II +l: !+i) can be kept in the state of 7U.

FIG. 7 shows an example in which the present invention is applied to fuel injection '9jVj, and there is basically no difference of 5°4 from the case of the fuel injection layer 7.

In the figure, 3jj is an intake pipe, 6 is a fuel injection valve, 7 is a fuel injection circuit 41, and the configuration of the pond is the same as in the previous embodiment.

In other words, 38 is the main body of Tsuki Seki, 39 is the exhaust pipe, 40 is Norconia [11.41 is the exhaust temperature a1.42 is the control command circuit, 43 is the air-fuel ratio control circuit, 44 is the throttle valve,
4! ) is the throttle switch.

Above 9, the circuit 37 has (intake air supply, rotational speed l, (offset 111, etc.), fuel injection 91 valve;
This system controls the appropriate injection amount and timing of fuel injection, and has the same function as a normal electronic ILI control fuel injection system.

Then, the oxygen meter 40 detects the oxygen concentration in the air, thereby detecting the air-fuel ratio of the combustion mixture, and based on this, the air-fuel ratio control circuit 44 controls the control signal 111 as a correction signal.
This signal is fed back to the 1ilf circuit 37, which causes the Hama p8 circuit 37 to correct the fuel injections 4, 3 and B'f set based on the other parameters, and perform proper fuel injection.

Then, in the same way as described in 111j, zirconia oxygen meter 4
() in the control command circuit 4.
In response to the interrupt signal 2, the air-fuel ratio control circuit 113 issues an alarm during feedback control or +EIi, and similarly sets the integral interest 1) to zero.

This correction lit for the arithmetic circuit 3-7 is ttS
It is set by the ratio 1 of resistors R1 and R2 shown in 6-1.

(Effects of the Invention) From what has been explained above, it can be concluded that according to the present invention, if the output of the oxygen concentration detection means is Since the signal that controls the air-fuel ratio is generated, it is possible to prevent the air-fuel ratio of the air-fuel mixture from fluctuating greatly from the set value, thereby improving the stability of the fuel-air mixture operation.

In addition, in this case, the output of the oxygen concentration detection stage F is determined by 111 times, so it is possible to accurately distinguish between the 5's and the 1's immediately after a month. )effective.

Furthermore, if the catalyst used to purify (-) the dominant components in the gas in the bleed system is destroyed, for example, a large amount of unburned components will flow into the catalyst and the catalyst temperature will rise above 8-1. Teyaki 411
In addition, it is possible to prevent situations such as
Generating an alarm using the output of normal calibration detection allows you to quickly check the output value of the exhaust gas component measuring device.
This driving thought 1 can be made known.

[Brief explanation of the drawing]

tIS1 is a block diagram showing an embodiment in which the present invention is applied to a vaporizer, FIG. 2 is a diagram showing the output characteristics of Norfnia Oxygen 111, and FIG. 3 is a diagram showing the output characteristics of Norfnia Oxygen 111.
, Figure 4 is a block diagram of the normal detection circuit, Figure 5 (a) is a block diagram of another embodiment of the abnormality detection circuit, and Figure 13 (b) is a diagram of the output waveforms of each part Figure 6 is an explanatory diagram showing the steps of the air-fuel ratio control circuit (main parts such as the fractional processing part are set to 1), and Figure 7 and 1 are blocks showing an embodiment in which the present invention is applied to a fuel injection device. This is a diagram. 1...
・Friendly crystal Jilil, 4... Zirconia oxygen meter, 5...
- Control command circuit, 6... Air-fuel ratio control circuit, 7... Carburetor, 8... Throttle pulse 7.5)... Throttle opening detection switch, 1 ()... Alarm device, 11...・・・
Abnormality detection circuit, 12... Rotation speed discrimination circuit 13... Temperature discrimination circuit, 14... AND date, 15... OR gate, 16... Maximum value 7;:1 Occasionally open detection circuit, 1
7... Minimum stay time detection circuit, 1 to 8... setting (
1ν generation mochi, 15) II, 191J・Comparison): (,2
4. Control reverse cut, 21)... Oscillator, nt).
・7 rip 70 knob, 27.28...and gate,
5)...Inverting circuit. #'r J' + Applicant 1" Sanjitaka Co., Ltd. Figure 1 Yu Figure 2 Kurenru Figure 3 Figure 1 Figure 4 Figure 5 (B) (C) (h) Figure 6 4 Figure 7 figure

Claims (1)

[Claims] An oxygen concentration detection means for detecting the oxygen concentration in the exhaust gas of the internal combustion engine, an air-fuel ratio determination means for comparing and determining the detected value from the acid a concentration detection means with a first set value, and from the air-fuel ratio determination means. In the air-fuel ratio feedback control device, the air-fuel ratio feedback control device includes a control means for performing feedback correction on the air-fuel ratio of the air-fuel mixture by at least integrating the discrimination value of a state determining means for comparing the second set value with the detected value from the oxygen concentration detecting means;
and an air-fuel ratio feedback control device comprising: a time limit means for detecting the output state of the state determining means and stopping feedback correction based on integral processing in the control means unless the output continues to change; .