JPH07269420A - Evaporated fuel supply control device for engine - Google Patents

Abstract

PURPOSE:To secure a large amount of purging under a rich condition by reducing an air-fuel ratio under a lean condition compared to the ruch condition where a large amount of evaporated fuel can be purged to an intake system, and setting a large reduction degree under the lean condition compared to that in the rich condition with a low intake amount. CONSTITUTION:At the time of purge control, purge executing condition is effected in the case that air-fuel ratio feedback control is executed and water temperature in an engine 1 is, for instance, 40 deg.C. Next, it is judged whether or not a lean burn execution condition is effected, which condition is that the engine water temperature is, for instance, 80 deg.C. When the answer is YES, a purge duty (Pduty) is set based on a map of an engine speed and charging efficiency (load). The Pduty is output to a purge solenoid valve 10 for purging evaporated fuel. When the lean burn execution condition is not effected, the Pduty is kept constant. When the purge execution condition is not effected, the Pduty is set zero for closing the purge solenoid valve 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of the supply amount of evaporated fuel generated in a fuel tank or the like to an intake system.

[0002]

2. Description of the Related Art In a vehicle engine, a canister traps vaporized fuel generated in a fuel tank (adsorption trapping).
Then, the trapped vaporized fuel is purged (released and released) from the canister during operation and supplied to the intake system of the engine to prevent atmospheric pollution due to diffusion of the vaporized fuel into the atmosphere. In this case, the purged evaporated fuel is usually introduced into the collecting portion (surge tank) of the intake passage via the purge passage.

By the way, there is known a lean burn control for feedback controlling the air-fuel ratio of the engine to a predetermined air-fuel ratio on the fuel lean side of the stoichiometric air-fuel ratio in a predetermined operation region in order to improve fuel efficiency. In an engine that performs both fuel injection and fuel vapor supply, if the fuel vapor supply amount changes during lean burn control, the feedback control is delayed and the fuel injection amount is delayed. There is a problem in that the fuel economy becomes rich and fuel efficiency deteriorates, and the engine becomes over lean and misfires occur to deteriorate combustion stability. Therefore, for example, as described in Japanese Utility Model Laid-Open No. 63-239355, the purge amount control is corrected so that the purge amount is reduced when the air-fuel ratio is lean and the purge amount is increased when the air-fuel ratio is rich. Has been proposed in the past.

[0004]

When changing the purge amount of the evaporated fuel according to the set air-fuel ratio, the conventional control is to reduce the purge amount by a certain amount when the set air-fuel ratio is lean compared to when it is rich. However, if the purge amount is reduced by a certain amount in this way regardless of the operating condition when lean, it is not possible to reduce the purge amount sufficiently in the region where the intake air amount is small, such as during idling, and combustion stability deteriorates. Cannot be prevented, or conversely, sufficient purging cannot be performed in a region where the intake air amount is large.

Further, when the evaporated fuel is introduced into the collecting portion of the intake passage as in the conventional case, the distribution amount to each cylinder varies, so the purge amount must be set in consideration of the variation in the distribution amount. Therefore, even when the set air-fuel ratio was rich, a sufficient large amount of purge could not be performed.

The present invention is intended to solve such a problem, and secures a large amount of vaporized fuel purge when the air-fuel ratio is rich and secures a purge amount of the vaporized fuel when lean, and stabilizes combustion. The purpose is to improve sex.

[0007]

According to the present invention, when the air-fuel ratio is lean, the degree of reduction of the purge amount is adjusted in accordance with the operating state to secure combustion stability while ensuring the purge amount as much as possible. Further, when the air-fuel ratio is rich, the purge amount is set uniformly regardless of the operating state, and the evaporated fuel supply control device for an engine is provided which is capable of ensuring a large amount of purge. The configuration according to (1) is based on the evaporated fuel supply means for supplying the evaporated fuel generated in the fuel system to the intake system and the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine, when the set air-fuel ratio is lean. A supply amount setting means for setting the supply amount of the evaporated fuel to be reduced with respect to the fuel rich state, and a rich time uniform setting for setting the supply amount of the evaporated fuel to be constant regardless of the intake air amount when the fuel is rich. A constant means and said to weight loss degree against time fuel rich supply amount of the fuel vapor with the lean time loss adjusting means for increasing as the low intake air amount when the fuel-lean.

Further, according to a second aspect of the present invention, the fuel vapor supply means for supplying the fuel vapor generated in the fuel system to the intake system, and the supply amount setting means for setting the fuel vapor supply amount by the fuel vapor supply means And, based on the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine, when the set air-fuel ratio is lean, the lean intake amount is increased, and the decrease amount of the evaporated fuel supply amount with respect to the fuel rich is increased. It is characterized by having a weight loss adjusting means.

Further, according to the third aspect of the present invention, the evaporated fuel supply means for supplying the evaporated fuel generated in the fuel system to the intake system, and the supply amount setting means for setting the supplied amount of the evaporated fuel by the evaporated fuel supply means And a rich time uniform setting means for making the supply amount of the evaporated fuel constant regardless of the operating region when the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine is set to the fuel rich side including at least the stoichiometric air-fuel ratio. It is characterized by having. Here, the set air-fuel ratio can be a stoichiometric air-fuel ratio. Further, the operating area may be an operating area defined by the intake air amount.

Further, in these configurations, when the engine is a multi-cylinder engine, it is preferable that the evaporated fuel supply means individually supplies evaporated fuel to the independent intake passage of each cylinder. In particular, it is preferable to supply the evaporated fuel to the vicinity of the injection port of the fuel supply injector provided for each independent intake passage of each cylinder.

When the injector supplies mixing air for atomizing the fuel near the injection port,
The evaporative fuel supply means may be configured to supply the evaporative fuel through the passage for supplying the mixing air.

The air-fuel ratio of the fuel lean is set to be leaner than the stoichiometric air-fuel ratio.

FIG. 1 is an overall configuration diagram showing the above configuration of the present invention.

[0014]

According to the evaporated fuel supply control device for an engine of the first aspect of the present invention, the evaporated fuel generated in the fuel system is supplied to the intake system, and the supply amount thereof is the mixture gas supplied to the combustion chamber of the engine. The set air-fuel ratio is reduced when the fuel is lean, as compared with the fuel rich when a large amount of purge is possible. And
The rich air supply amount is constant regardless of the intake air amount, which ensures a large amount of purge, while the lean intake amount is set to be larger for a low intake air amount, which results in stable combustion even when lean. The purge amount is secured in the high intake amount region where the effect on the fuel efficiency is small, and the deterioration of combustion stability is prevented in the low intake amount region.

According to the engine fuel vapor supply control device of the second aspect of the present invention, in particular, when the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine is lean, the lower the intake air amount, Control is performed to increase the degree of decrease in the supply amount of the evaporated fuel when the supply amount is rich, whereby the purge amount is secured in the high intake amount region where the influence on combustion stability is small even when lean, and in the low intake amount region. Deterioration of combustion stability is prevented.

According to the third aspect of the present invention, there is provided the fuel vapor supply control system for the engine, wherein the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine is set to the fuel rich side including at least the stoichiometric air-fuel ratio. At this time, control is performed so that the supply amount of the evaporated fuel is constant regardless of the operating region, whereby a large amount of purge is secured.

Further, according to the evaporated fuel supply control device for an engine of the fourth aspect of the present invention, the supply amount of evaporated fuel is made constant when the set air-fuel ratio of the air-fuel mixture supplied to the engine is the stoichiometric air-fuel ratio. Control is performed.

According to the fifth aspect of the present invention, there is provided the fuel vapor supply control system for the engine, wherein the intake air is drawn when the set air-fuel ratio of the air-fuel mixture supplied to the engine is set to the fuel rich side including at least the stoichiometric air-fuel ratio. Control is performed so that the supply amount of evaporated fuel is constant regardless of the air amount.

Further, in the case of the evaporated fuel supply control device for an engine according to the sixth aspect of the present invention, the evaporated fuel is individually supplied to the independent intake passage of each cylinder, and particularly, the evaporated fuel is, for example, mixing air. When the air-fuel ratio is fuel rich and lean when the air-fuel ratio is rich, the distribution is improved by being supplied to the vicinity of the injection port of the fuel supply injector through the fuel passage. In this case, a large amount of purge can be performed in the high intake amount region. Further, since the evaporated fuel is supplied to each cylinder in this way, it is possible to set the evaporated fuel supply timing for each cylinder. Therefore, it is possible to supply the evaporated fuel together with the fuel injection timing in the latter half of the intake stroke. As a result, even if the injection amount from the injector due to the feedback control decreases due to the influence of the purge amount, a rich air-fuel mixture can be secured around the spark plug, and lean burn due to stratification can be secured.

According to the fuel vapor supply control system for an engine of the seventh aspect of the present invention, the fuel efficiency of the engine is improved because the lean setting is leaner than the stoichiometric air-fuel ratio.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is an overall view of an embodiment of the present invention.
In this embodiment, the engine 1 has four cylinders, and an injector 4 for supplying fuel for each cylinder is installed in an independent intake passage 3 branched from the surge tank 2. These injectors 4 are so-called AMIs (air mix injectors) that supply mixing air for atomizing fuel to the vicinity of the injection port, and an AMI air supply path 6 having an air control valve 5 that closes at idle and at high load is used. It branches on the downstream side and is connected to each injector 4. A bypass passage 7 that bypasses the air control valve 5 is also connected to the AMI air supply passage 6, and the bypass passage 7 is provided with an orifice 8 that allows a small amount of air to flow during idling.

In the figure, 9 is a purge passage extending from a canister (not shown), and 10 is a purge solenoid valve. The purge passage 9 is formed in the mixing chamber 1 formed upstream of the branch point of the AMI air supply passage 6.
Connected to 1. The vaporized fuel generated in the intake system such as the fuel tank and trapped in the canister is guided to the mixing chamber 11 through the purge passage in a predetermined operation region, and then the injection port of each injector 4 through the AMI air supply passage 6. It is supplied to the vicinity and is supplied to the combustion chamber 12 of each cylinder together with fuel spray in the latter half of the intake stroke.

The air control valve 5 is closed at the time of idling and at the time of high load, and is opened at other operating regions.

Further, the purge solenoid valve 10
Is driven when a predetermined purge execution condition is satisfied,
The duty is controlled according to the operating state of the engine 1 so that a predetermined purge amount is obtained. The purge amount is set uniformly (for example, 20% in duty ratio) regardless of the engine speed and load in the operating region where the air-fuel ratio of the engine is set to the theoretical air-fuel ratio (14.7). On the other hand, during the lean burn control, the purge amount is made smaller than that in the operating region where the rich setting, that is, the stoichiometric air-fuel ratio is set, and the reduction amount thereof is increased as the intake air amount becomes lower as shown in FIG. The numbers in FIG. 3 indicate the purge duty.

Next, the purge control will be specifically described with reference to the flow chart shown in FIG.

When the flowchart of FIG. 4 starts, various signals such as the engine speed and the intake air amount are input for setting the purge amount in step S1.

Next, the purge execution condition is determined in S2. Here, when the air-fuel ratio feedback control is being executed and the engine water temperature is, for example, 40 ° C. or higher, the deviation of the air-fuel ratio due to the purge can be absorbed by the feedback control, so that the purge execution condition is satisfied (flag x
It is determined that pg = 1).

When the purge execution condition is satisfied in S2, S3
Then, it is checked whether the lean burn execution condition that the engine water temperature is, for example, 80 ° C or higher is satisfied. If the lean burn execution condition is satisfied (flag xlean = 1), in S4, the purge duty Pduty is set in accordance with the map of the engine speed Ne and the charging efficiency Ce (load) shown in FIG. 3, and the Pduty is set to S5. To output to the purge solenoid valve 10.

When the lean burn execution condition is not satisfied in S3, it means that the stoichiometric air-fuel ratio setting is in the feedback region, so the routine proceeds to S6, where Pduty is uniformly set to α (for example, 20%), and it is purged in S5. Output to the solenoid valve 10.

When the purge execution condition is not satisfied in S2, the purge duty Pduty is set to 0 (zero) in S7.
And

Although the purged evaporated fuel is supplied to the vicinity of the injector nozzle through the AMI air supply passage in the above embodiment, the evaporated fuel can be supplied directly to the injector nozzle. .

The present invention can be implemented in various other modes.

[0034]

According to the engine evaporated fuel supply control device of the first aspect of the present invention, the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine is the amount of the evaporated fuel supplied to the intake system. Compared to the fuel rich when the set air-fuel ratio is large enough to be purged, the amount is reduced when the fuel is lean, the supply amount during rich is constant regardless of the intake air amount, and the degree of reduction relative to rich during lean is set to be large for low intake air amounts. As a result, a large amount of purge can be secured at the time of rich, and at the time of lean, the purge amount is secured at a high intake amount region that has little effect on combustion stability, and combustion stability is deteriorated at a low intake amount region. Can be prevented.

According to the evaporated fuel supply control device for an engine of the second aspect, when the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine is lean, the lower the intake air amount, the smaller the supply amount of the evaporated fuel. By performing control to increase the amount of reduction in the rich condition, it is possible to secure the purge amount in the high intake amount region that has little influence on the combustion stability even when lean, and to prevent the deterioration of the combustion stability in the low intake amount region. You can

According to the fuel vapor supply control system for an engine of the third aspect of the invention, the engine is operated when the set air-fuel ratio of the air-fuel mixture supplied to the combustion chamber of the engine is set to the fuel rich side including at least the stoichiometric air-fuel ratio. A large amount of purge can be ensured by making the supply amount of the evaporated fuel constant regardless of the region.

Further, according to the fuel vapor supply control system for an engine of the fourth aspect of the present invention, when the set air-fuel ratio of the air-fuel mixture supplied to the engine is the theoretical air-fuel ratio, the fuel vapor is supplied regardless of the operating region. A large amount of purge can be ensured by keeping the amount constant.

According to the fuel vapor supply control system for an engine of the fifth aspect of the present invention, the engine is operated when the set air-fuel ratio of the air-fuel mixture supplied to the engine is set to the fuel rich side including at least the stoichiometric air-fuel ratio. A large amount of purge can be ensured by making the supply amount of the evaporated fuel constant regardless of the region.

Further, according to the evaporated fuel supply control device for an engine of the sixth aspect, the evaporated fuel is individually supplied to the independent intake passages of the respective cylinders, whereby the distributability is improved and the evaporation to each cylinder is improved. It is possible to reduce the variation in the fuel supply amount and enable further large-scale purging in the high intake amount region. Further, by supplying the evaporated fuel to each cylinder in this way, it is possible to secure lean burn due to stratification. Further, when the evaporated fuel is supplied to the vicinity of the injection port of the fuel supply injector as in claim 7, the evaporated fuel can be supplied through the mixing air supply passage, and the above effect is made remarkable. You can

According to the fuel vapor supply control device for an engine of the eighth aspect, the fuel vapor can be supplied through the passage for mixing air.

According to the fuel vapor supply control system for an engine of the ninth aspect, the fuel efficiency of the engine can be improved because the lean setting is leaner than the stoichiometric air-fuel ratio.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is an overall view of an embodiment of the present invention

FIG. 3 is a control map according to an embodiment of the present invention.

FIG. 4 is a flowchart for executing control according to an embodiment of the present invention.

[Explanation of symbols]

 1 engine 3 independent intake passage 4 injector 6 air supply passage for AMI 9 purge passage 10 purge solenoid valve

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasuyoshi Hori 3-1, Shinchi Fuchu-cho, Aki-gun, Hiroshima Prefecture Mazda Motor Corporation

Claims (9)

[Claims] 1. When the set air-fuel ratio is fuel lean based on a set air-fuel ratio of an air-fuel mixture supplied to a combustion chamber of an engine and an evaporated fuel supply means for supplying evaporated fuel generated in a fuel system to an intake system. Supply amount setting means for reducing the supply amount of the evaporated fuel with respect to when the fuel is rich, and uniform rich time setting means for setting the supply amount of the evaporated fuel to be constant regardless of the intake air amount when the fuel is rich. An engine fuel vapor supply control device, comprising: lean fuel consumption reducing means for increasing the fuel vapor rich fuel vapor reduction amount when the fuel is lean, as the intake air amount decreases. 2. Evaporative fuel supply means for supplying the evaporated fuel generated in the fuel system to the intake system, supply amount setting means for setting the supply amount of the evaporated fuel by the evaporated fuel supply means, and supply to the combustion chamber of the engine. On the basis of the set air-fuel ratio of the air-fuel mixture that is set, when the set air-fuel ratio is lean, the lean amount reduction adjusting means is provided for increasing the amount of reduction of the supply amount of the evaporated fuel with respect to the fuel rich when the intake air amount is low. A feature of an engine fuel vapor supply control device. 3. Evaporative fuel supply means for supplying evaporated fuel generated in the fuel system to the intake system, supply amount setting means for setting the supply amount of evaporated fuel by the evaporated fuel supply means, and supply to the combustion chamber of the engine. An engine provided with a rich time uniform setting means for making the supply amount of the evaporated fuel constant regardless of the operating region when the set air-fuel ratio of the air-fuel mixture to be set is at the fuel rich side including at least the stoichiometric air-fuel ratio. Evaporative fuel supply control device. 4. The evaporated fuel supply control device for an engine according to claim 3, wherein the set air-fuel ratio is a stoichiometric air-fuel ratio. 5. The evaporated fuel supply control device for an engine according to claim 3, wherein the operating region is an operating region defined by an intake air amount. 6. The evaporated fuel for an engine according to claim 1, wherein the engine is a multi-cylinder engine, and the evaporated fuel supply means individually supplies evaporated fuel to an independent intake passage of each cylinder. Supply control device. 7. The evaporated fuel supply control device for an engine according to claim 4, wherein the evaporated fuel supply means supplies evaporated fuel to the vicinity of the injection port of the fuel supply injector provided for each independent intake passage of each cylinder. . 8. The injector supplies mixing air for atomizing fuel to the vicinity of the injection port, and the evaporated fuel supply means supplies evaporated fuel via a passage for supplying mixing air. The evaporated fuel supply control device according to claim 5. 9. The evaporated fuel supply control device for an engine according to claim 1, wherein the air-fuel ratio of the fuel lean is set to be leaner than the stoichiometric air-fuel ratio.