JPS5835246A - Air-fuel ratio controller of engine - Google Patents

Abstract

PURPOSE:To change air-fuel ratio in an adequate condition at switching of a control system when a fixed control system at specific operation is switched to a feedback control system at normal operation, by providing a correcting means in which a control gain of the feedback control system is temporarily increased. CONSTITUTION:A control circuit 8 is constituted in such a manner that a timer 21 is provided and started when an operational condition-detector circuit 17 detects the switching from a specific operational condition to a normal oprational condition, after a prescribed time, the integrating coefficient of an integrator 13 is changed from K2 to K1, while at transfer from a fixed control system to a feedback control system, a control gain of the feedback control system is held higher for a certain time. In this way, when rich air-fuel ratio of fixed control, for instance, in a high loaded operational condition is switched to air-fuel ratio of feedback control in an normal operational condition, the air-fuel ratio can be changed in an adequate condition without causing the shocking change to an engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for an ennon, and more particularly, to a working fuel ratio control device that allows an engine to be operated at the most favorable air-fuel ratio according to various conditions of an ennon. Regarding loading.

In Ennon equipped with a catalyst in the exhaust system for exhaust gas control, the purification ability of the catalyst changes depending on the air-fuel ratio of the intake air-fuel mixture. There is a device equipped with an exhaust gas component sensor that detects the amount of exhaust gas bi, and does not control the air-fuel ratio depending on the amount of exhaust gas bi to maximize the purification H power of the catalyst. ing. Steady operation condition 70I where Ennon is operated at almost constant speed and - load
- In operating conditions where the load fluctuations are relatively slow, there is no particular problem with this type of air-fuel ratio control, but when starting the ennon and In certain operating ranges such as engine speed, idling, acceleration/deceleration, etc., steady operating conditions require the supply of an air-fuel mixture with a true nitrogen/fuel ratio. For this reason, conventional.

In addition to feedback control that controls the air-fuel ratio according to the concentration of exhaust gas 1 + 32 minutes detected by the exhaust gas component sensor, the air-fuel ratio control device controls the air-fuel ratio to a predetermined value according to the operating state in a specific operating region. W constant f! that sets the air-fuel ratio. II
#e, and is configured to switch between feedback control and fixed control depending on the operating range.

However, such conventional air-fuel ratio control devices may give satisfactory results when the operating state continues, but when switching from a fixed control system to a feedback control system, the setting during fixed control There is a considerable difference between the air-fuel ratio and the target air-fuel ratio during feedback control, and the feedback control system normally performs control by integral control operation.
It takes a considerable amount of time to set the air-fuel ratio from the air-fuel ratio during specific operation to the target air-fuel ratio during normal operation using the feedback control system, and the response is slow.

In order to improve the responsiveness of this air-fuel ratio control,
In the air-fuel ratio feedback type mixture control device described in the '7023 publication, when the fixed control system for specific operation is changed to the feedback fftlJ control system for normal operation, the fuel injection lit 1blI In the correction circuit that finally corrects the N signal according to the engine operating conditions, this control signal is corrected based on the difference in the appropriate air-fuel ratio between specific operation and normal operation, and this corrected control The fuel injection device is controlled by the signal. However, in this air-fuel ratio feedback mixture control device, as mentioned above, the fuel injection sound control signal is directly corrected based on the difference in the appropriate air-fuel ratio between specific operation and normal operation. Therefore, there is no delay due to the above-mentioned feedback control and integral control, but when the control system reaches 17I, that is, when the operating state is switched, the fuel ratio decreases too rapidly, so the engine operating state vC There is a risk of a debt-like fluctuation.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an air-fuel ratio control method for an engine that does not have the above-mentioned hm in air-fuel ratio control when switching from a fixed control system to feedback control light.

The engine air-fuel ratio control device according to the present invention has a fuel-fuel ratio of 1.
When the #1 yarn is switched from a fixed control system during a specific operation to a feedback control system during normal operation, a correction means is provided to temporarily increase the control gain of the feedback control system. It is.

As a means for increasing the control gain, the integral coefficient for feedback control may be increased for a certain period of time after switching from fixed control to feedback control. Alternatively, the air-fuel ratio may be controlled using an integral coefficient until the input signal value to the integrating means of the control system is reversed, and after the reverse is performed using a lower integral coefficient.

According to the engine air-fuel ratio control device of the present invention having such a configuration, the control gain of the explosive speed control system is temporarily increased when switching the control system, so that the control gain of the explosion speed control system is temporarily increased when switching the control system. Therefore, by changing the air-fuel ratio under the same conditions, there will be no shocking changes in the operating conditions of the Ennon.

Hereinafter, an engine air-fuel ratio control device according to a preferred embodiment of the present invention will be described with reference to the attached page □□□.

FIG. 1 is an overall configuration diagram of an air-fuel ratio control device for an engine 1 according to the present invention.

The engine 1 has an intake passage 2 and an exhaust passage 8. An intake negative pressure sensor 4 is disposed in the intake passage 2, and an exhaust sensor 5 consisting of an oxygen concentration sensor is disposed in the exhaust passage 8. On the upstream side of the intake negative pressure sensor 4 in the liquid @ pipe 2, the operation is controlled via an actuator 6 consisting of a solenoid valve that opens and closes an air leader, for example, to adjust the air-fuel ratio of the intake air, such as vaporization gain. Fuel #A111
A device 7 is provided. A control valve 8 is connected to the fuel type device 7 for controlling the air-fuel ratio of the air-fuel mixture based on the detection output of the intake negative pressure sensor 4 and the side output of the exhaust sensor 5. This ll+l control circuit 8 will be explained in detail later. This control circuit 8 compares the concentration configuration signal Sl of the exhaust sensor 5 with a set voltage Vref indicating the target air-fuel ratio from the set voltage generating circuit 9, and generates a deviation signal @S2 indicating the VA difference. A soft circuit IO is connected. In the figure, reference numeral 11 indicates an air cleaner, and reference numeral 12 indicates an air cleaner provided in the exhaust passage 8. : Indicates each device.

Next, the control circuit 8 of the engine air-fuel ratio control device of the present invention will be explained in detail with reference to FIG.

The control circuit 8 includes an integral calculator 18 connected to the comparator IO.
This integral calculator 18 is equipped with λ, whose integral coefficient is the integral coefficient for normal operation.

The integral coefficient k'/2 is selectively set to an integral coefficient larger than the integral coefficient k'/2.

The integral calculator 18 performs an integral calculation in accordance with an integral coefficient based on the deviation signal S2 from the comparator IO during normal operation, and outputs a duty ratio control signal S3. A drive circuit 14 is connected to the integral calculator 18, and the drive circuit 14 controls the drive of the actuator 6t based on the duty ratio control signal S3.

The control circuit 8 thus constitutes a feedback control system during normal operation 4.

On the other hand, reference numeral 15 indicates a fixed control signal output circuit of a fixed control system for a specific operating state of the engine 1, and this fixed control signal output circuit 15 is connected to the integrator 1B via a gate 16. When the integral compensator 18 receives the fixed control H-Is'jj S II from the fixed control signal output circuit 15, it stops its integral action and outputs the human power as it is. f-) 16 is connected to the operating state detection circuit 17, and this operating state detection circuit l? The system detects the operating state of the engine based on the detection output of the negative pressure sensor 4, and opens the door 16 when the operating state of the engine 1 is in a specific operating state such as a one-load operating state.

Operating state detection circuit l? An integral coefficient setter I8 is connected to the integral coefficient setter I8, and this integral coefficient setter 18 is connected to , integral! This command instructs to switch the integral coefficient of 613 to kl force/ra niko. This integral coefficient setter 18 is connected to a switching circuit 9 via an inverter 20 or
It is directly connected through 0. The inverter 20 is a ram 4
This is a book in which the number of r squads kl, k, and 2 are inverted, that is, -kl, -1. Switching circuit 19a, comparator IO
The integration coefficient of the integrator 18 is set to one of , k2, -, -, and l based on the deviation signal s2 which is the output of the integrator 18. In the figure, reference numeral 21 is a timer, and this timer 21 starts when the operating state detection circuit 17 detects that the normal operating state Vc has been switched from the specific operating state, and the timer 21 starts operating when the operating state is switched from the specific operating state to the normal operating state Vc. I - This is to switch the integral coefficient from 2 to /.

Next, the operation of the circuit 8 having the configuration shown in FIG. 2 will be explained with reference to FIGS. 3 and 9.

For example, during normal operation of engine 1, engine 1
Assuming that the air-fuel ratio of the mixture supplied to the air-fuel mixture fluctuates as shown in FIG. S/ is compared with the set voltage Vref from the set voltage generation circuit 9 to output a deviation signal s2 as shown in FIG.
] consists of a high level portion, ie, a portion RI/q, which indicates that the concentration detection signal S/ is larger than the set voltage Vref, and a low level portion, ie, a portion θ”, which indicates that the concentration detection signal S/ is smaller than the set voltage Vref. Vessel 1i# Vessel↓3 is
Based on this -difference ifI signal S2, the integral coefficient kl is integrated by -//, and a duty ratio control signal 53 as shown in FIG. 3(C) is output. Body solicitation lol? ! r11 drives and controls the actuator 6 based on this Gunnity ratio control signal S-3, and performs feedback air-fuel ratio II control so that the air-fuel ratio of the intake air-fuel mixture converges to the set `JPY ratio.

When performing the return air-fuel north side operation as described above, the operating state detection circuit 17 switches from the normal operating state to the hourly conduction state and, if ν1j, to the high-load operating state based on the output of the negative pressure sensor 4. When detecting τ, the driving state detection circuit 17 detects the dirt 16. Therefore, the fixed control signal Sda from the fixed control signal output circuit 15 is an integral wave 14. The feedback control system is stopped by stopping the operation of the DAN-BUN'II4 device 18. As a result, the fixed control signal sg is delivered to the drive circuit 14 in its luxurious state.

Thus, the drive circuit 14 receives the fixed control signal S! Based on this, the actuator 6 is controlled one step at a time, and air-fuel ratio control is performed so that the air-fuel ratio of the intake air-fuel mixture becomes, for example, a constant rich value.

On the other hand, when the operating state detection circuit &817 detects that the specific operating state has changed to the normal operating state Kf, the integral coefficient of the integral calculator 18 is set to 2 or - to the verification coefficient setting 618 via the switching circuit 19. Replace 2VcgJ. The integrator 18 performs an integral calculation based on the deviation signal S2 of the comparator 10 with an integral coefficient of 2 or -2, and outputs a duty ratio control signal S3. This state is timer 2
11C after a predetermined time ill T, and the integral calculator 18 again performs its operation based on the integral coefficients /, - and /. Changes in the air-fuel ratio as a result of this control are shown in curves l1lilR in FIG. As is clear from this diagram, the air-fuel ratio is rich in the fixed control during % foot driving! R/, when fixed control is switched to feedback control 'gQ, the air-fuel ratio changes transiently at a desired slope as in part R2 due to the effect of 2 on the integral coefficient, and then changes by the effect of integral coefficient kl. Due to part R3
Normal feedback control is performed as follows. In addition, in FIG. 9, the solution shows the state of change in the air-fuel ratio when switching from fixed control to feedback control without intermediate correction stage.
teeth#! This figure shows the changes in the air-fuel ratio in the same case as above using the ratio feedback type mixture control device of No. J Kaisho 5 '7-'70.23.

In addition, in this example, the integral coefficient is
After f is set to 2 and after fc, the timer 21 is used to invert to 2, and then the integral coefficient adder 18 is connected to the comparator lO as shown in FIG. And this comparator】0
The integral coefficient may be returned from 2 to 2 when the one-stroke signal S output from Oq to q/gevC1 or from I//L/ to θη. Further, in the above embodiment, one difference Ig signal S of the comparator 10
An integral calculator 18, i.e., a computer, was used to divide the number of minutes, but instead of this integral calculator 18, a normal integrator sound using light and discharge metal could be used. In this case, the inverter 20 is not required.

[Brief explanation of drawings]

In other words, all 14 configuration diagrams of Ryumei Mok's 1-engine engine control port, and Figure Ω shows the control of the engine's silent north side mount shown in Figure 7. Glock 1 and 3 (Al
, (81, (C) are the revised diagrams showing the changes in the blank ratio, 4-degree detection 16 hooks, and duty ratio control signals, respectively. Figure 4 shows the change from the fixed control system to the return M control system). (
fc, by the air-to-furnace ratio control head of the engine of the present invention.
11.4J showing the change in air-fuel ratio controlled by tI++
, 5 is a block diagram showing a modification of the altII control circuit. 1... Engine, 4... Negative pressure sensor, 5... Exhaust sensor, <S... Actuator, 7... Fuel #12
Leg pain device, 8... Chi' (Incorporated Foundation) circuit, 9... Setting voltage generation circuit, 1 (1... Comparison circuit, 18... Integral calculator, 15... bs + constant control Signal output circuit, 17.
・・Driving letter special detection profit, ■ 8 ・・Establishment of noodle coefficient.

Claims (1)

[Claims] During normal engine operation, the actual zero-fuel ratio is detected by detecting the concentration of engine exhaust gas components, and the detected air-fuel ratio near the dormitory is compared with the target air-fuel ratio to detect the difference in the rain air-fuel ratio. a feedback control system that controls the air-fuel ratio to the target air-fuel ratio based on the difference in the air-fuel ratio; and a fixed control system that fixes and maintains the air-fuel ratio at a desired value according to the operating condition wllK during a specific operation of the engine. Consisting of
In the air-fuel ratio control device in which the feedback control system and the fixed control system are switched and operated according to the operating state of the engine, the control system is switched from the fixed control system to the feedback control system. 1. An air-fuel ratio control device for an engine, comprising a correction means for temporarily increasing a control gain of the feedback control system when the feedback control system is changed.