JPS62223440A - Suction system for engine - Google Patents

Abstract

PURPOSE:To secure combustibility so favorably as well as to aim at improvement in travelability, by checking the rarefaction of an air-fuel ratio even in a specific driving range at the time of something trouble in a swirl forming device. CONSTITUTION:At the time of transition from the fixed driving range where lean combustion of an air-fuel mixture is not carried out to the specified driving range performing it the other way, a swirl control valve 18 closes a main suction passage 16 and a small quantity of suction air is fed to a combustion chamber from an auxiliary suction passage alone, thereby producing a swirl there, while an air-fuel ratio of mixture is regulated to the lean side by a controller 46. Here, when trouble in a swirl forming device is detected by a swirl valve opening sensor 43 or a swirl valve closing sensor 44 at the fixed driving range, rarefaction of the air-fuel ratio is checked. Therefore, even after transition to the specified driving range afterward, the air-fuel ratio of mixture is not varied at all, there fore like in case of the fixed driving range, favorable combustibility is secured as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an engine intake system, and in particular, generates a swirl in a combustion chamber in a specific operating range such as when the engine is running at low speeds and under low load. Concerning improvements that made book burning possible.

(Prior art) Conventional J: As disclosed in, for example, Japanese Unexamined Patent Publication No. 59-7776, an intake system for this type of engine has a sub-intake passage in addition to a main intake passage communicating with the combustion chamber. At the same time, the amount of intake air flowing through the sub-intake passage is determined by W4.
In specific operating ranges such as low rotation and low load, the control valve supplies a predetermined volume of intake air from the auxiliary intake passage to the combustion chamber, generating a swirl in the combustion chamber. Is the air-fuel ratio of the mixture to the combustion chamber rare? JIIIl
It is known that the combustion speed is increased even in a lean air-fuel mixture by adjusting the air-fuel mixture to l, thereby improving fuel efficiency while ensuring a good combustion state of the air-fuel mixture.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional system, when the control valve is operating normally, swirl is generated in the combustion chamber and the air-fuel mixture is diluted in a specific operating range of the engine. Therefore, lean combustion of the mixture is well ensured, but in the event of an abnormality in which the normal function of the control valve is impaired, the coincidence relationship between the occurrence of the swirl and the 11fiia of the mixture becomes 11, and the combustibility of the mixture deteriorates. A problem arises in that the value decreases. In other words, if the control valve fails and is kept in the open state 14, only the mixture will be leaner after the transition to the specific operating range, resulting in a half-misfire.

The present invention has been made in view of these points, and its purpose is to reduce the amount of swirl generated by the above-mentioned S11 tall valve, etc. ``If Ω is held open due to a failure, swirl will be generated in the combustion chamber and 1g will not be produced, so the combustion of the mixture will be controlled at the stoichiometric air-fuel ratio or over-enriched as in the areas other than the above specified operating area. By setting the air-fuel ratio on the side, a good combustion condition is ensured and the half-misfire caused by the conventional setting of the air-fuel ratio on the lean side is prevented, and the engine runs with good combustibility. The aim is to improve sexual performance.

(Means for solving the problem) In order to achieve the above object, the solution means of the present invention (Means for solving the problem)
The air-fuel ratio of the 15-air gas (supplied to the combustion chamber in a specific operating range of the engine) is set to 31'J' so that it is leaner than normal.
: P''j air-fuel ratio adjustment means; swirl generation means for generating swirl in the combustion chamber in the specific operating region; and prevention of dilution of the air-fuel ratio by the air-fuel ratio adjustment/r-stage when the swirl generation means fails. The structure is such that a means for prohibiting lean driving is provided.

(Function) With the above configuration, the present invention enables lean combustion of the air-fuel mixture. Is this from a predetermined operating area? When transitioning to the 7 specific operating range, the swirl generating means normally operates and swirl is generated in the combustion chamber, and the air-fuel ratio of the air-fuel mixture is adjusted to the 4-volume side by the air-fuel ratio adjusting means. Regardless of the lean state of the air-fuel mixture, the combustion speed of the air-fuel mixture is increased due to the generation of the L-swell, and the combustion of the air-fuel mixture is performed satisfactorily, thereby improving fuel efficiency.

If the swirl generating means fails during the predetermined operation in which the air-fuel mixture is not lean-burned, swirl will not be generated even after the subsequent transition to the specific operation region. However, in this case, since the lean operation prohibition means prevents the air-fuel ratio from being leaner by the air-fuel ratio adjustment means, the combustion of the air-fuel mixture does not change, and the J J: Good 17 is ensured, and half-misfire caused by dilution of the air-fuel ratio does not occur as in the conventional case.As a result, combustibility is improved and running performance is improved.

(Example) Embodiments of the present invention will be described below based on the drawings.

In FIG. 1, 1 is a four-cylinder engine, 2 is a combustion chamber formed with a variable volume by a piston 4 that is movably inserted into a cylinder 3 of the engine 1, and 51 is connected to an air cleaner 6 at one end. The (l!2 end is connected to the atmosphere through the combustion chamber 2 and the intake passage 7 is for supplying intake air to the engine 1. The (l! is an exhaust passage that is open to the atmosphere and discharges exhaust gas, and in the middle of the intake passage 5 is a throttle valve 8 that controls the amount of intake air, and a throttle valve 8 that injects and supplies fuel downstream of the throttle valve 8. In addition, an intake valve 10 is provided at the opening of the intake passage 5 to the combustion chamber 2. On the other hand, an intake valve 10 is provided at the opening of the intake passage 5 to the combustion chamber 2. In addition, an exhaust valve 11 is provided at the frontage.
A catalyst device 12 for purifying the exhaust gas is interposed in the middle of the path 7. Furthermore, an ignition plug 13 is disposed at the top of the combustion chamber 2 to ignite the air-fuel mixture within the combustion chamber 2 .

The intake passage 5 near the combustion chamber 2 is divided vertically into two parts by a partition wall 15, and has a main intake passage 16 with a large passage area;
A nI intake passage 17 with a small passage area is formed, and a swirl control valve 18 (hereinafter abbreviated as a swirl valve) for opening and closing the main intake passage 16 is arranged in the main intake passage 16. When the swirl valve 18 is closed, a swirl is generated in the combustion chamber 2 by closing the main intake passage 16 and supplying a small amount of intake air only from the auxiliary intake passage 17 to the combustion chamber 2 from the side. When the swirl valve 18 is opened, the main intake passage 16 is opened so that a large amount of intake air is supplied from the main intake passage 16 in addition to the a1 intake passage 17 into the combustion chamber 2 without generating swirl. .

Further, a diaphragm device 21 for opening and closing the swirl valve 18 is connected to the swirl valve 18 via a link mechanism 2O. As shown in enlarged detail in FIG. 2, the diaphragm device 21 includes a diaphragm 21a connected to the link mechanism 20, an f9 pressure chamber 211 defined on the left and right sides in the figure by the diaphragm 21.1, and A spring 21d is compressed in the negative pressure chamber 21b, and an air intake passage 5 is connected to the negative pressure chamber 21b via the negative pressure passage 22.
Negative pressure can be introduced into a negative pressure reserve tank 23 that stores intake negative pressure downstream of the throttle valve 8, and atmospheric pressure can be introduced through an atmospheric passage 24. In addition, the negative pressure passage 2
In the middle of the atmospheric passage 24, there is a negative pressure introduction part 25 that controls the permission/stop of the introduction of negative pressure into the negative pressure chamber 211), and in the middle of the atmospheric passage 24, there is a negative pressure introduction part 25 that controls the introduction of negative pressure into the negative pressure chamber 211). Atmospheric pressure introduction portions 26 for controlling introduction/stopping are respectively provided.
j, the negative pressure reserve tank 23 is
When zero pressure is introduced into the negative pressure chamber 21b of the diaphragm device 21, the diaphragm 21a resists the biasing force of the spring 21d and moves in the direction of IE in the figure. While rotating clockwise in the figure to close the main intake passage 16, when atmospheric pressure is applied to the negative pressure chamber 2'I +3 by the popular rE introduction part 26, the die (fluorum 21a) By separating the part to the right in the figure due to the urging force of the spring 21d, the swirl valve 18 is rotated counterclockwise in the figure, and the main intake passage 16 is rotated counterclockwise in the figure.
The device is configured to be actuated to open the device.

Incidentally, the negative pressure introducing section 25 has a condition that ln'+ <
, first and second opening/closing valves 30.31 for introducing negative pressure that respectively open and close the first pressure passage 22a and the second angular pressure passage 22b that divide the negative pressure passage 22 into two, and the second negative pressure passage 22b.
The negative pressure chamber 21 of the diaphragm device 21 is
The speed at which negative pressure is introduced into the engine is set in binary order, so that the closing speed of the main intake passage 16 by the swirl valve 18 can be changed as appropriate. Similarly, the atmospheric pressure introduction section 26 has first and second atmospheric pressure introduction sections that open and close a first atmospheric passage 24a and a second atmospheric passage 24b, which are divided into two parts of the atmospheric passage 24.
1) valves 33, 34 and a throttle section 35 interposed in the second atmospheric passage 34, and both on-off valves 3
5.36, the rate of atmospheric air introduction into the negative pressure chamber 21b of the diaphragm device 21 is set to binary, and the swirl valve 18 is
The opening speed of the main intake passage 16 is changed accordingly.

In FIG. 1, 37 is an ignition coil, and 38 is a power distributor that distributes the high voltage generated by the ignition coil 37 to the spark plug 13.

In addition, in FIG.
An air flow sensor 41 measures the amount of intake air on the upstream side of the throttle valve 8, a throttle sensor 41 detects the opening degree of the throttle valve 8, and 42 measures oxygen in the exhaust gas on the upstream side of the catalyst device 12 in the exhaust passage 7. This is an exhaust sensor that detects the air-fuel ratio based on moisture content. Furthermore, in FIG. 2, 43 is a swirl valve closing sensor that comes into contact with the link mechanism 20 of the swirl valve 18 when the swirl jf 18 is closed, and detects when the link mechanism 20 is closed; The swirl valve opening sensor detects when the link machine tM 20 of the swirl valve 18 is in contact with the link machine tM 20 when the swirl valve 18 is opened. Cylinder identification signals from the power distributors 38 are input to controllers 46 each having a built-in CPU, etc., and the controllers 46 control the negative pressure introduction section 25J3 and the atmospheric pressure introduction section 26, so that the swirl valve 18 is connected to the engine. It is designed to open and close depending on the operating condition.

Next, the Swarm? by the controller 46? The opening/closing control of the valve 18 will be explained at 70-1 in FIG.
In order to determine the open/close state of the swirl valve 18, the output signals of the swirl valve close sensor 43 and the swirl valve open sensor 44 are read, and when the swirl valve 18 is closed, the close flag FLGI is set to "1". ) At 1 o'clock, 1ji1 o'clock flag F l-G 2 is set to "1".

However, in step S2, the intake air RFt Q A- Shinchi from the air flow sensor 40 is detected, and the ignition coil 37/
) After reading the engine speed N signals of 1 and 1, in Step S3 and Sa, the engine operating state is in the air-fuel ratio lean setting range preset according to the engine speed - intake air amount shown in Fig. 4. This −? li
Bookkeeping window setting area QA <QA o, N<N.

In the case of YES, a target air-fuel ratio on the lean side is set in step S5 in order to perform lean combustion of the air-fuel mixture, and
In step S6, the swirl valve 18 is closed to close the main intake passage 16, and a swirl is generated in the combustion chamber 2. On the other hand, if NO is not in the lean setting region, that is, if it is in the normal region of the stoichiometric air-fuel ratio or in the power FJ'i region of higher power, the stoichiometric air-fuel ratio or the target air-fuel ratio on the rich side is set in step S7. At the same time, the swirl valve 18 is activated in step S8.
is operated to close the main intake passage 16, thereby stopping the generation of swirl.

If it is in the sparse setting area, step S9
After that, take measures against failure of the swirl valve 18, and if it is in the normal range or power range, proceed to step S +
After step s, measures are taken in case of failure of the swirl valve 18.

First, to explain the case where it is in the sparse setting region, 1111 of the step S.l'c closing flag FLGI is determined,
When FLG1=1 is closed, it is determined that it is normal with swirl occurring, and the process immediately proceeds to step 810. In step S+a, the fuel injection valve is adjusted so as to reach the target air-fuel ratio on the lean side in step S5. 9 to 117fi
After controlling flag FLG1. in step S.sub.U. F
Initialize both LG2 to "0" and return. On the other hand, if the closed state flag FLG1-0 is NO in step S9, the state is not closed.

Further, in step S12, the value of the open flag FLG2 is determined, and when FLG2-0 shifts to the NO sparse setting area,
That is, if the swirl valve 18 is in the middle of being moved in the closing direction, the target air-fuel ratio for this transient state is set in step S13, and the process sequentially proceeds to step 5IOIS11. On the other hand, in the case of a failure in the open state of the swirl valve 18, where the open flag FLG2-1 is YES in step S12, the target air-fuel ratio is set to the lean side in step S14 due to the non-occurrence of swirl. After resetting the air-fuel ratio to the stoichiometric air-fuel ratio or rich side, the process proceeds to step SI0.811, where lean combustion of the air-fuel mixture is prohibited.

In addition, if it is in the normal region or power region, the value of the open flag FLG2 is determined in step S+s, and the value of the open flag FLG2 is determined,
When G2=1 (YES) is in the open state, it is determined that there is no failure and there is no failure, and the step SIQ is performed immediately.

Proceed to So and adjust the air-fuel ratio to stoichiometric or rich side. On the other hand, in the case of NO in FLG2-0, step S16
The close flag FLG1 (directly determines whether the swirl valve 18 is operating normally in the closing direction or when it has failed.
If FLGl-0 is normal, the over3
! [Set the intermediate target air-fuel ratio and proceed to steps S+o, Su
Proceed to. On the other hand, when FLG1=1 is YES and the swirl valve 18 is closed? & At camp, the target air-fuel ratio is 1! P
Since it is on the W or rich side, it is decided to retard t91[a at the time of ignition of the spark plug 13, and this retard amount ΔIg is set to Sudet/S17, the intake air ff1QA, the engine speed N(13 and the current air-fuel ratio). Once determined, the ignition timing Ti1l is retarded by this retard amount Δ1g in step S+s, and then in step SIQ.
, the process proceeds to S11 and the air-fuel ratio is adjusted to the stoichiometric or over) side.

Therefore, in the operation flow shown in FIG. 3 above, step $
1 to S5 and S9 to S0 are used to adjust the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber 2 in a specific operating range (lean setting range) of the engine to be leaner than in the normal range or power range. In step 83.84, Ss, the swirl valve 18 is closed in the lean setting region and intake air is supplied to the combustion chamber 2 only from the auxiliary intake passage 17, and the air-fuel ratio adjustment means 50 is configured. A swirl generating means 51 is configured to generate a swirl within the air. Further, in steps 89 and 812° S14, when the swirl generating means 51 fails, the target air-fuel ratio is reset to the theoretical or rich side, and the air-fuel ratio adjusting means 5
A lean operation inhibiting means 52 is configured to prevent the air-fuel ratio from becoming lean due to zero.

Therefore, in the above embodiment, when the swirl generating means 51 is normal and there is no failure, when the engine operating state shifts from the normal region or power region to the lean setting region,
The air-fuel ratio of the air-fuel mixture is adjusted to the lean side by the air-fuel ratio adjusting means 50, and the swirl valve '18 of the swirl generating means 51 is closed to generate swirl in the combustion chamber 2.
The air-fuel mixture in the combustion chamber 2 has a high combustion speed and burns well regardless of the air-fuel ratio set on the lean side. the result,
While maintaining a good combustion state, the fuel consumption is reduced by the air-fuel ratio lean setting valve, thereby improving fuel efficiency.

On the other hand, if the swirl generating means 51 fails in the normal region or the power region, for example, S) from the negative pressure passage 22
If the swirl valve 18 is fixed in the open state due to pressure leakage or sticking of the negative pressure introducing on/off valves 30 and 31, the swirl valve 1 remains open even after the subsequent transition to the rare 7i9 setting region.
8 is fixed in the open state, no swirl occurs in the combustion chamber 2, and if the air-fuel mixture is burnt lean, a half-misfire will occur. However, in this case, when the air-fuel ratio is set to the lean side by the air-fuel ratio adjusting means 50, the lean operation prohibiting means 50
2, and the air-fuel ratio is reset to the stoichiometric or receding side, so that the combustion of the air-fuel mixture is maintained satisfactorily without any change in C as in the normal region or power region. Therefore, when a failure occurs when the swirl valve 18 is in an open state, it is possible to reliably prevent the occurrence of half-misfire in the 'b rare R specified region, ensure good combustibility, and effectively prevent a decrease in running performance. can do.

Furthermore, when the swirl generating means 51 fails, if the swirl valve 18 is fixed in the closed state in the lean setting region, the air-fuel ratio of the mixture will be in the normal range thereafter, regardless of the state in which the intake air amount cannot be increased. Or, although it is set from the lean side to theoretical or over'allll when transitioning to the power range, the ignition timing [a of the spark plug 13 is retarded by a predetermined period Δ■9, so that the combustion state of the air-fuel mixture is maintained as much as possible. It is possible to effectively improve the output while ensuring good performance.

(Effects of the Invention) As explained above, according to the present invention, in an engine intake system that enables lean combustion of the air-fuel mixture by generating a swirl in the combustion chamber in a specific operating range of the engine, the air-fuel mixture In the event of a malfunction in which swirl is not generated in the lean burn region, lean combustion of the air-fuel mixture is prohibited to reliably prevent the occurrence of half-misfires, so even in the event of such a malfunction, the combustion state of the air-fuel mixture can be maintained in good condition and the vehicle can be driven. It is possible to improve sexual performance.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and Fig. 1 is a general 4R diagram, Fig. 2 is an enlarged view of the main part of Fig. 1, Fig. 3 is a flowchart showing the operation of the controller, and Fig. 4 is a simplified diagram. FIG. 3 is an explanatory diagram showing a setting area, a normal area, and a power area. DESCRIPTION OF SYMBOLS 1... Engine, 2... Combustion chamber, 5... Intake passage, 9... Fuel injection valve, -16... Main intake passage,
17... Sub-intake passage, 18... Swirl control valve, 21... Diaphragm device, 46... Controller, 50... Air-fuel ratio adjusting means, 51... Swirl generating means, 52... Lean driving prohibition measures.

Claims (1)

[Claims] (1) An air-fuel ratio adjustment means that adjusts the air-fuel ratio of the air-fuel mixture supplied to the combustion chamber in a specific operating range of the engine so that it is leaner than usual; and a swirl that generates a swirl in the combustion chamber in the specific operating range. An intake system for an engine, comprising: a generating means; and a lean operation inhibiting means for preventing the air-fuel ratio adjusting means from diluting the air-fuel ratio when the swirl generating means fails.