JPS58167847A - Air-fuel ratio control equipment in engine - Google Patents

Abstract

PURPOSE:To enrich the air-fuel ratio of intake mixed air while oxygen concentration in the exhaust system is held to be the determined value in such a way that a part of intake air is fed from understream of an intake air quantity detecting means to upstream of an exhaust gas sensor, in response to the running condition of an engine. CONSTITUTION:A control unit 7 controls the injecting time of an injection nozzle 6a in arithmetic operations on the basis of detected values of an intake air quantity detecting means 4, a throttle sensor 14, a revolution number sensor 13, a temperature sensor 15, an exhaust gas sensor 9, etc. An air feeding path 11 equipped with an air pump 16 and a control means 12 is provided between upstream of the intake air quantity detecting means 4 in an intake air path 2 and upstream of an echaust gas sensor 9 in an exhaust air path 8, and a control means 12 is opened in the operational range where preferably thicker mixed air is fed in the engine thus the intake mixed air can be enriched. While the oxygen concentration in the exhaust gas to flow into ternary catalyst 10 is being maintained to its determined value.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-fuel ratio control device for an engine.

For the purpose of exhaust purification, for example, when a three-way catalyst is installed to simultaneously reduce He, 0θ, and NOx in the exhaust, in order to make the most effective use of the function of the three-way catalyst, it is necessary to When supplying the air-fuel mixture or secondary air, set the total air-fuel ratio (the weight ratio of the fuel amount to the sum of the secondary air amount and the engine intake air amount) to the stoichiometric air-fuel ratio or a very close range ( To achieve this, conventionally, an exhaust gas sensor is installed in the engine exhaust system to detect the concentration of exhaust components that are closely related to the air-fuel ratio of the air-fuel mixture in the engine intake system. A fuel supply means for controlling the amount of fuel supplied according to the output of the exhaust gas sensor is installed in the intake system of the engine, thereby keeping the air-fuel ratio of the engine intake mixture almost constant. For example, when a three-way catalyst is installed, the air-fuel ratio is maintained at the stoichiometric air-fuel ratio. A feedback air-fuel ratio control method has been proposed.

By adopting the above method, it is possible to improve the exhaust gas purification function by constantly setting the air-fuel ratio to a predetermined value (for example, the stoichiometric air-fuel ratio). Although the engine rotation will become unstable if the air-fuel ratio of the intake air-fuel mixture is not made small, that is, the intake air-fuel mixture is not enriched, the air-fuel ratio is always kept at a constant air-fuel ratio, so the engine There is a problem with lack of stability.

Therefore, in order to ensure the stability of the engine, it is possible to release the feedback control and make the intake air-fuel mixture richer than the stoichiometric air-fuel ratio during idle operation, low-speed operation, and when the engine is cold. Even if the stability of the engine can be ensured by doing so, the exhaust purification efficiency of the catalyst will be reduced.

Therefore, in an engine equipped with a three-way catalyst, the total air-fuel ratio is maintained at the stoichiometric air-fuel ratio by supplying secondary air during engine idling, low-speed operation, and cold running, and the three-way catalyst Japanese Patent Laid-Open No. 51 (1973) has already proposed a method to reduce the air-fuel ratio of the engine intake air-fuel mixture to ensure engine stability without reducing the exhaust purification efficiency.
-66984.

However, with this bridge device, during idling, low-speed rotation, and cold conditions, the exhaust gas sensor is
The air-fuel ratio is detected as being larger than the air-fuel ratio of the intake air-fuel mixture supplied to the engine, and a correction signal is output based on this detection signal to adjust the air-fuel ratio of the intake air-fuel mixture. I'm trying to keep it small.

In other words, the exhaust gas components related to the exhaust gas senna are ternary recaptured* (exhaust gas state a when the air-fuel ratio of the intake air-fuel mixture is 14.7, which is the stoichiometric air-fuel ratio). A correction signal is output (Fig. 4C), and based on this, the air-fuel ratio of the intake air-fuel mixture becomes the stoichiometric air-fuel ratio (14,7)C.
Due to this change in the air-fuel mixture, the exhaust gas components upstream of the three-way catalyst in the exhaust system become essentially a three-way atmosphere, and the three-way contact V & improves exhaust gas purification. When engine cooling is being carried out, during idling or low-speed operation, secondary air is introduced from the atmosphere or upstream of the air flow sensor to ensure engine stability. The air-fuel ratio upstream of the catalyst increases, and the air-fuel consumption of the intake air-fuel mixture is reduced based on the correction signal that detects this low concentration air-fuel ratio. )
, and once the air-fuel ratio upstream of the catalyst increases until it reaches the stoichiometric air-fuel ratio, that is, from the above 0 point (Pl)
There is a barrier that causes a considerable delay (1) before reaching the point.

This invention was developed to address the above-mentioned conventional problems, and the air in the intake system measured by an intake air amount detection means such as an airflow sensor that measures the amount of intake air is introduced upstream of the catalyst to ensure engine stability. An object of the present invention is to provide an air-fuel ratio control device for an engine that can secure engine stability and improve catalyst purification efficiency without causing the above-mentioned conventional delay. This will be explained with reference to the drawings.

In Figures 1 and 2, (1) is the engine, (2
) is an intake passage, and in this intake passage (2), an air arena (3), an intake air amount detection means (4) for measuring the amount of intake air, a throttle valve (5), and a fuel supply means (6) are installed from upstream. A spray nozzle (6&) is provided.

The intake air amount is detected by the intake air amount detection means (4)K-, and this detection signal is input to the injection opening calculation circuit (7b) of the control unit (7). The output of the control unit (7) is then input to the fuel supply means (6), whereby the amount of fuel supplied to the engine (1) is controlled according to the intake/air amount, and the injection nozzle of the fuel supply means (6) is controlled. (
-) is injected from.

(8) is the exhaust passage, and from its upstream side is the exhaust gas sensor (9).
), for example, O!, which outputs a signal depending on the oxygen concentration in the exhaust gas. It is equipped with a seven-ringer and a three-way catalyst αQ.

Exhaust gas sensor above? The output signal of (9) is the control enin)(
7) and corrected by the air-fuel ratio correcting means (7a) (see Figure 2) of Control Ennin) (7) is input to the injection time calculation circuit (7b) and calculated, thereby fuel is supplied. The amount of fuel supplied by means (6) is controlled to be in the vicinity of the stoichiometric air-fuel ratio.

aυ indicates an air supply passage; this air supply passage (b) is comprised of an intake 9IC passage (2) immediately downstream of the intake air amount detection means (4) and an exhaust branch (2) immediately upstream of the exhaust gas sensor (9). 8), and a control means (6) for controlling opening and closing of the air supply passage συ according to the operating state of the engine (1) is provided in the middle thereof.

On the other hand, the water temperature sensor installed in the engine (1)? (To) and the detection signal of the Xa torque sensor Q4 are input to the discrimination circuit (7C) of the flilJ m unit (7), and the discrimination circuit (
7c), the operating state is determined, and its output signal is input to the drive circuit (1) of the control means (2).

Further, the detection signal of the speed sensor (to) is input to the injection time calculation circuit (7b).

A is a drive mechanism composed of an air pump, which is installed in the air supply passage α, and when the control means (2) is open, part of the air in the intake passage (2) is transferred to the exhaust passage (
8), and when the control means @ is blocked, it is circulated through a circulation path (16b) equipped with a check valve (16&) that allows flow only to the arrow direction.

Note that the drive mechanism can also be constructed from known lead pulp.

In the above configuration, during steady operation of the engine (1),
The detection signal of the intake air amount detection means (4) and the speed cent
The detection signal of I is manually input to the injection time calculation circuit (Wb), and the detection signal of the exhaust gas sensor (9) is input to the air-fuel ratio correction means (7a), and the air-fuel ratio is adjusted based on the scissors input signal. The output signal of the correction means (7a) is input to the injection time calculation circuit (7b), and the fuel supply means (6) is controlled by the output signal of the injection time calculation circuit (7b).

Therefore, the engine (1) is supplied with an intake air-fuel mixture having a stoichiometric air-fuel ratio (14,7) as shown in FIG. 8a. In this case, the output signals from the water temperature sensor (to) and throttle center tQ4 are determined by the discrimination circuit (7C) to be steady operation, and no signal is output from the discrimination circuit (7C), so the drive circuit (12m) is not driven. The control means (2) closes the air supply passage (b).

Therefore, as shown in Fig. 8b, the air-fuel ratio in the exhaust passage (8) becomes near the stoichiometric air-fuel ratio (14,7) based on the correction signal (Fig. 8c) similarly to the intake air-fuel mixture, and the three-way catalyst Q1
Exhaust gas can be efficiently purified.

On the other hand, during idling or low-speed operation, the suit torque sensor a◆ detects this, and the detection signal is sent to the discrimination circuit (7).
C). In addition, when it is cold, the water temperature sensor α
] detects this and uses the detection signal as a discrimination circuit (70).
Enter. In these cases, the discrimination circuit (7C)
The control means (6) is operated to open the anastrual air supply passage (α) by determining the above state and outputting a signal to the drive circuit (1).

For this purpose, the intake air amount detection means (4) of the intake passage (2) is
) A part of the downstream air is introduced into the exhaust gas sensor (9) and the upstream exhaust passage (8) through the air supply passage αchin (P)
.

At this point, the exhaust gas immediately upstream of the three-way catalyst 013 is maintained in a three-way atmosphere, that is, the total air-fuel ratio is maintained at a value close to the original stoichiometric air-fuel ratio, and large fluctuations as shown in FIG. 4b are avoided. does not occur. Therefore, even during transitions from steady operation to idling, low-speed operation, or cold/cold operation where you want to supply a rich mixture to the engine,
Since the exhaust gas flowing into the three-way catalyst continues to be maintained at a level suitable for purification, the conventional problem of a temporary decrease in exhaust gas purification performance is resolved.

In addition, since the example described was equipped with a three-way catalyst, feedback control was performed to the stoichiometric air-fuel ratio.
The air-fuel ratio to be controlled by the feed batter is appropriately set depending on the type of catalyst provided, and the present invention is not limited to the embodiment i.

Further, in this embodiment, the control means (6) is a drive circuit (12).
(m) is operated in an on/off manner, but of course it may be variably controlled depending on the requirements of the operating state.

As described above, according to the present invention, a portion of the intake air in the intake passage downstream of the intake air amount detection means is transferred to the exhaust passage upstream of the exhaust gas sensor via the air supply passage according to the operating condition of the engine. Because it is configured to be introduced with
This has the advantage that responsiveness during transitions when the engine operating condition changes is improved, and there is no delay as in the prior art.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of the air-fuel ratio control device according to the present invention, and FIG.
The figures are diagrams of the same splitter, Figures 8a to 30 are operational characteristic diagrams, and Figures 41 to 4C are operational characteristic diagrams of the conventional example. (2)...Intake passage, (4)...Intake air amount detection means, (6)...Fuel supply means, (7m)...Correction means, (8)...Exhaust passage, (9 )...Exhaust gas sensor, α-me...Air supply passage, (6)...Control means. Patent applicant: Toyo Kogyo Co., Ltd. Procedural amendment June 131, 1982 Dear Commissioner of the Japan Patent Office, 1. Indication of the case 1973? -0sla41t 2. Name of the invention Nijiyyog fuel ratio control device 3. Relationship with the person making the amendment. Patent applicant address: 11 Shinchi, Fuchu-cho, Anbu, Hiroshima Prefecture. Name (3118) Toyo Kogyo Co., Ltd. 4. Agent. Postal code 550 "Detailed description of the invention" in the specification. 7. Answer A for amendment, Specification 1 (1) Correct the word "HC" in the first line of page 2 and circle it as "HC". (2) On page 4, line 14, Tororu will be corrected to ``Tororu,'' as ``Tororu,'' to read ``Tororu,'' to read. (3) Page 5, line 5, ``Air fuel consumption'' has been corrected to ``Air fuel ratio.'' (4) On page 8, line 19, the phrase “air-fuel ratio” is replaced with “Ganu component (air-fuel ratio) of the exhaust gas”
We will correct it. (5) In the first line of page 9, the phrase ``stoichiometric air-fuel ratio'' has been corrected to ``three-dimensional calculation air.''that's all

Claims (1)

[Claims] (1) an intake air amount detection means disposed upstream of the intake passage to measure the intake air amount; and a fuel supply means that controls the amount of fuel supplied to the engine based on the detection signal of the cough intake air amount detection means; An air-fuel ratio control device for an engine, comprising: a correction means for correcting the amount of fuel supplied by the fuel supply means based on a detection signal from an exhaust gas sensor disposed in an exhaust passage; an air supply passage that supplies part of the intake air in the intake passage to the exhaust passage upstream of the exhaust gas sensor, and a control means for controlling the amount of air supplied through the air supply passage according to the operating state of the engine. An air-fuel ratio control device for an engine, comprising: