JPH05113154A - Variable suction control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To mitigate the torque shock in a variable suction control device for internal combustion engine so arranged as to cause EGR performance at the time when a swirl control valve disposed in a suction passage is closed, and to cause a reduction in the EGR quantity at the time when the swirl control valve is opened, by causing the EGR quantity to be controlled in such a direction as to decrease a change in output torque as the swirl control valve is operated. CONSTITUTION:A combustion chamber 12 is formed with a first suction port 14a which is a helical swirl port for forming a suction swirl in the combustion chamber 12, and a second suction port 14b which is a straight port. A fuel injection valve 26 is disposed on a partition wall 28 between branch passages 20a, 20b branching from a common suction passage 20 which are connected to the suction ports 14a, 14b, respectively. An EGR port 38 is provided to one mentioned branch passage 20a, and this EGR port 38 is connected to a discharge pipe 18 via an EGR pipe 34 with respect to which an EGR valve 35 is disposed while, on the other hand, a swirl control valve 32 is provided in the other mentioned branch passage 20b. As the swirl control valve 32 is operated, the EGR valve 35 is controlled so as to adjust the EGR quantity in such a direction as to decrease the resulting torque change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable intake control system for an internal combustion engine equipped with a swirl control valve for controlling intake swirl generation in a combustion chamber.

[0002]

2. Description of the Related Art A helical port formed in a spiral shape so as to generate a strong swirl (swirl flow) of intake air in a combustion chamber, and a combustion chamber that is branched from an intake passage and does not go through the spiral portion of the helical port. A straight passage that connects to
And a swirl control valve for closing the straight passage,
During low-speed low-load operation of an engine with a small intake air amount, the control valve is closed to allow most of the intake air to flow into the combustion chamber through the spiral portion of the helical port to generate an intake swirl, and at the same time, the engine speed with a high intake air amount is high. A variable intake control device is known in which the control valve is opened during load operation to allow intake air to flow in from the straight passage as well to reduce intake resistance.

In this type of intake control device, the turbulence of the air-fuel mixture is promoted by the strong swirl generated in the combustion chamber when the swirl control valve is closed, and the combustion state is improved. Therefore, when the swirl control valve is closed, the combustion state is not deteriorated and the drivability is not deteriorated even if the mixture is diluted or a large amount of exhaust gas recirculation (EGR) is performed. An example of this type of intake control device is the device disclosed in JP-A-59-49359. The intake control device of the same publication supplies lean mixture to the combustion chamber when the swirl control valve is closed and performs EGR to improve fuel efficiency and reduce NOx components in exhaust gas without impairing drivability during low load operation. Achieved at the same time. Also,
When the swirl control valve is opened, the air-fuel mixture having the stoichiometric air-fuel ratio is supplied to the combustion chamber and the EGR is stopped to secure a large output.

[0004]

Generally, in a control device using a swirl control valve, the output characteristic of the engine changes abruptly by opening / closing the swirl control valve. For this reason, if the swirl control valve is opened / closed when the engine speed gradually changes, such as during gentle acceleration or on an uphill road, a torque shock unexpected to the driver may occur, which impairs driving sensation. There is.

Further, when the EGR is performed, the engine output torque is reduced as compared to when the EGR is stopped due to a decrease in intake volume efficiency, etc. Therefore, when the EGR is stopped together with the swirl control valve opening as in the above-mentioned JP-A-59-49359. , The torque increase due to the swirl control valve opening and the torque increase due to the EGR stop are added to further increase the torque shock. It is possible to reduce the torque shock by retarding the ignition timing or increasing the amount of fuel when the swirl control valve is opened to prevent a sudden torque increase when the swirl control valve is opened. Corners, increased fuel, etc. are not preferable because they significantly deteriorate fuel efficiency.

In view of the above problems, it is an object of the present invention to provide a variable intake control device capable of reducing torque shock when a swirl control valve is opened / closed and without causing a significant deterioration in fuel consumption.

[0007]

According to the present invention, a swirl control valve is provided in an intake passage, and the swirl control valve is closed under a predetermined condition to generate an intake swirl in a combustion chamber, and the swirl control is performed. In a variable intake control device for an internal combustion engine, which performs exhaust gas recirculation when the valve is closed and reduces the exhaust gas recirculation amount when the swirl control valve is open, an output accompanying opening / closing of the swirl control valve during the swirl control valve opening / closing operation. There is provided a variable intake control device for an internal combustion engine, which controls the exhaust gas recirculation amount in a direction to reduce a torque change.

[0008]

In the swirl control valve opening / closing operation, the EGR amount is controlled so that the change in the engine output torque due to the increase / decrease in the EGR amount and the change in the engine output torque due to the opening / closing operation of the swirl control valve cancel each other out. That is, when the swirl control valve is opened, the EGR amount is increased so that the output torque decrease due to the EGR increase and the output torque increase due to the swirl control valve opening occur at substantially the same time, and the rapid torque increase due to the swirl control valve opening is mitigated. .. When the swirl control valve is closed, the EGR amount is reduced so that the output torque increase due to the EGR reduction amount and the output torque decrease due to the swirl control valve closing occur at substantially the same time, thereby mitigating the sudden torque decrease due to the swirl control valve closing. To do.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing the structure of an embodiment of an internal combustion engine to which the variable intake control device of the present invention is applied. In the figure, 10 indicates an engine cylinder head. Although a multi-cylinder engine is used in this embodiment, the drawing shows only the cylinder head of one cylinder.

Reference numeral 12 denotes a cylinder combustion chamber, and the combustion chamber 1
2 has a four-valve configuration in which two intake ports 14a and 14b and two exhaust ports 16a and 16b are provided. The first intake port 14a is a swirl port formed in a helical shape to form an intake swirl (swirl flow) in the combustion chamber 12, and the second intake port 14b is a straight straight port. The intake passage 20 connected to each cylinder of the cylinder head 10 has a partition wall 2
8 separate from each other, and independent branch passages 20a and 20b connected to the intake ports 14a and 14b, respectively.
Is formed. The partition 28 has intake ports 14a, 14
A communication passage 27 that communicates both the branch passages 20a and 20b is opened in the vicinity of b, and the communication passage 27 of the partition wall 28 is formed.
A fuel injection valve 26 is arranged in the portion.

The fuel injection valve 26 is provided with two injection ports 26a and 26b in one main body.
The a and 26b are opened in the communication passage 27 and are arranged so as to inject fuel toward the swirl port 14a and the straight port 14b, respectively. A swirl control valve (hereinafter referred to as “SCV”) 32 having a plate-shaped valve body is provided in the branch passage 20b following the straight port 14b to close the branch passage 20b.

When the SCV 32 is closed, most of the intake air passes through the branch passage 20a and is sucked into the combustion chamber 12 from the swirl port 14a. Therefore, a strong swirl is generated in the combustion chamber 12, and combustion is promoted by stirring the air-fuel mixture in the combustion chamber. As a result, even if the fuel injection amount is reduced and the air-fuel ratio of the air-fuel mixture is increased (diluted), good combustion can be maintained, and fuel efficiency can be improved.

On the other hand, when the SCV 32 is opened, intake air flows through both branch passages 20a and 20b, so that a large amount of air is introduced into the combustion chamber 12 and a large output can be secured. Further, in this embodiment, the EGR port 38 is provided in the intake pipe branch passage 20a communicating with the swirl port 14a. The EGR port 38 is an EGR pipe 34, an EGR
It is connected to the exhaust pipe 18 via a valve 35. EG
The R valve 35 is a solenoid type flow control valve and controls the amount of exhaust gas injected from the exhaust pipe 18 into the branch passage 20a via the EGR port 38.

In this embodiment, when the SCV32 is closed, the air-fuel mixture is diluted and the EGR is performed. However, when the SCV32 is closed, the combustion state is improved, so that the combustion becomes unstable even if a large amount of EGR is performed. Therefore, it is possible to reduce NOx in the exhaust gas by introducing EGR, reduce the intake pipe negative pressure at low load, reduce pumping loss, and improve fuel efficiency.

The conventional EGR port is the surge tank 3
Although it was provided in the intake pipe on the upstream side of 0, the exhaust gas was supplied from one port to all the cylinders, but in the present embodiment, the branch passage 20a following the swirl port 14a of each cylinder.
An individual EGR port 38 is provided on the downstream side of the communication passage 27. The EGR port 38 is provided on the downstream side of the communication passage 27 by allowing the EGR gas to directly flow into the cylinder from the swirl port 14a without passing through the SCV 32 and the communication passage 27, so that the EGR gas is provided in the vicinity of the SCV 32 and the communication passage 27. This is to prevent carbon and dirt components in the exhaust gas from adhering and causing dirt and clogging. Also swirl port 14a
By performing EGR from only the side, the amount of fresh air flowing from the helical port 14a side to the straight port 14b side through the communication passage 27 at the time of closing the SCV 32 is increased.
The atomization of the fuel injected from the fuel injection valve 26 to the straight port 14b side is improved, the wall temperature rise of the straight port 14b side branch passage 20b due to EGR gas is prevented, and the passage through the branch passage 20b is opened when the SCV is opened. There is no occurrence of knocking or reduction in intake volume efficiency due to a rise in the temperature of intake air that flows in as a result.

Reference numeral 50 in the drawing denotes an electronic control unit (ECU) for controlling the engine. ECU 50 is a CPU
(Central processing unit), RAM (random access memory), ROM (read only memory), a digital computer of a well-known type including an input / output port,
In addition to performing basic control of the engine such as fuel injection control from the fuel injection valve 26 and ignition timing control, the opening / closing control of the SCV 32 and the EGR valve 3 are performed according to the engine load and the rotational speed.
The EGR amount control by 5 is executed.

For the above control, the ECU 50 has an air flow meter 48 provided upstream of the throttle valve of the intake pipe.
From the engine speed sensor 49 provided in the distributor (not shown) of the ignition device and a pulse signal proportional to the engine speed (NE) from the engine speed sensor 49 provided to the throttle valve. A voltage signal proportional to the throttle opening (TA) is input from the throttle opening sensor 47.

The output port of the ECU 50 is SCV3.
An appropriate type of actuator 32a for opening and closing 2,
The solenoid valve of the GR valve 35 is connected via a drive circuit (not shown) to control the opening / closing of the SCV 32 and the EG.
The opening degree of the R valve 35 is controlled. Next, FIG. 2 shows the SCV32 opening / closing conditions of this embodiment. The vertical axis of FIG. 2 represents the intake air amount (Q / N) per engine revolution as a parameter representing the engine load, and the horizontal axis represents the engine speed NE. As can be seen from FIG. 2, the SCV 32 is set to open at a lower engine speed (NE) as the engine load (Q / N) is higher, and the valve opening speed of the SCV 32 linearly changes as the load decreases. It is going to rise.

The ECU 50 stores the opening / closing conditions of FIG. 2 in the form of a numerical table in the ROM, calculates Q / N based on the intake air amount Q and the engine speed NE, and according to the opening / closing conditions of FIG. The open / close control of the SCV 32 is performed. Further, in the present embodiment, the EGR amount is also controlled according to the engine load and the engine speed, and the EG is controlled in the low load region when the SCV 32 is closed.
The R amount is large and is controlled so as to gradually decrease in the high load region, and the EGR amount is set to be substantially zero in the vicinity of the SCV opening / closing condition. In this embodiment, S
Steady EGR is not performed during the CV opening operation.

Next, FIG. 3 shows changes in engine output due to SCV opening / closing and EGR. The vertical axis of FIG. 3 indicates the engine output torque (TR
Q), the horizontal axis represents the engine speed (NE), and solid lines A and C
Is the output torque when the SCV is closed and when the valve is open in the EGR OFF state, and the dotted lines B and D show the same amount of EGR.
The output torque when the SCV is closed and when the valve is opened is shown.

As shown in the figure, when EGR is performed both when the SCV is opened and when the valve is closed, the intake volume efficiency is reduced and the output torque is reduced. Although not shown, the output torque decrease range increases as the EGR amount increases. As described above, in this embodiment, the EGR amount is set to be substantially zero near the SCV opening / closing condition. Therefore, when the SCV is closed, S
In the vicinity of the CV opening / closing condition, the engine output torque is on the solid line A in FIG. Now, when the load and the rotational speed gradually increase due to, for example, slow acceleration, the operating condition is point I on the solid line A.
If the SCV is opened when the temperature reaches, the operating state shifts from the point I on the solid line A to the point II on the solid line C (SCV open, EGR OFF). Therefore, if the throttle opening is kept the same, the torque suddenly increases with the opening of the SCV and a torque shock occurs.

Similarly, when the engine speed gradually decreases due to traveling on an uphill road when the SCV is opened, the operating state shifts from the point II on the solid line C to the point I on the solid line A by closing the SCV. As a result, the output torque will decrease sharply.
In this embodiment, EGR is performed at the time of SCV opening / closing operation, and the operating state is dotted line D (SCV open, EGR ON) and solid line A (SC
The change in output due to switching is reduced by controlling to move between V close and EGR OFF).

FIG. 4 shows the SC when the SCV valve is opened during slow acceleration.
The V operation, the EGR control, and the accompanying changes in the rotational speed NE, the output torque TRQ, and the throttle valve opening TA are shown.
Referring to FIG. 4, since the section I is the operation in the SCV valve closing region and is in the state of gentle acceleration, the throttle opening TA (corresponding to the accelerator depression amount) TA and the torque TR are shown as shown in the figure.
Both Q and the rotational speed NE are gradually increasing. Also S
The CV is closed and the SCV opening condition is not satisfied. Further, since the operating condition is near the SCV valve opening condition, the EGR amount is almost zero.

Next, when the rotational speed and the load increase to enter the SCV opening region, the SCV opening condition is satisfied. In this embodiment, at this time point, the SCV is not opened and the EGR is performed first,
SCV closes and EGR ON during time T _{1 after} the valve opening condition is satisfied
Operate in this state (Fig. 4, Section II). Where T ₁ is E
This is the time from the GR ON to when the EGR effect appears and the engine output decreases. T ₁ is usually about 1 second, although it depends on the engine type and the like. Next, the time after the start of EGR T ₁
The SCV is opened when is passed, but at this time EG
Since the effect of R ON appears, the torque increase due to SCV valve opening and the torque decrease due to EGR ON cancel each other out, and large torque fluctuation does not occur (FIG. 4, section III).

After the SCV valve is opened, the EGR is stopped after a lapse of time T ₂ from the satisfaction of the SCV valve opening condition, and thereafter, the SCV is opened.
The operation is performed in the open and EGR OFF state (section IV in FIG. 4, time T ₂ is about twice the time T ₁ ). The change in the operating state at the time of switching will be described with reference to the output torque curve of FIG. Now, a point I (SCV
When the switching condition is satisfied with (closed, EGR OFF), only the EGR is turned on while the SCV remains closed (Fig. 4, section II).
However, since the effect of EGR does not appear immediately, the output torque does not immediately decrease, and the operating condition in Fig. 4 and section II is Fig. 3.
It remains near the point I on the solid line A.

After a lapse of time T ₁ from EGR ON, the EGR effect appears and the output torque decreases, but at the same time, the SCV is opened (section III in FIG. 4,).
Operating conditions are from point I on solid line A to dotted line D (SCV
Open, EGR ON) and move to point II '. Therefore, point I
The change in output torque is smaller than that in the case of shifting from point II to point II, and the torque shock associated with opening the SCV is alleviated. When time T ₂ elapses after the SCV valve opening condition is satisfied, EG
Since R is turned off (section IV in FIG. 4,), the operating condition shifts from point II ′ on the dotted line D in FIG. 3 to point II on the solid line C.
The change in output torque due to EGR OFF is relatively small, and a large torque shock does not occur.

The curve of the rotational speed NE, the torque TRQ, and the throttle opening TA in FIG. 4 when the SCV is opened will be described. As described above, in the section I, NE, TRQ, and TA gradually increase, but in the section II, since the EGR is turned on, both the rotational speed NE and the torque TRQ tend to decrease. However, since the throttle opening TA is increasing, the amount of decrease is small. When the vehicle enters the section III in this state, the SCV opens and the torque TRQ increases, but at the same time, the torque decrease due to the effect of the EGR causes a small torque increase width. Therefore, the driver does not have to suddenly return the accelerator pedal, and the change in the throttle valve opening TA is gentle.

On the other hand, the dotted line in FIG.
NE and TR when SCV is opened without turning R on
This is a change in Q and TA. In this case, the change in the torque TRQ due to the opening of the SCV is large, so the change in the rotational speed NE is also large, and the driver needs to rapidly return the throttle opening (accelerator pedal) in order to correct the acceleration more than expected. I understand that

Next, FIG. 5 shows time-dependent changes in the SCV operation and EGR control during the SCV valve closing operation, such as when climbing a slope, and the accompanying rotational speed NE, output torque TRQ, and throttle valve opening TA. In FIG. 5, the section I shows the operation in the SCV valve opening region, and since the vehicle is traveling on a gentle uphill road, the throttle opening TA is kept substantially constant and the rotational speed NE gradually decreases. Further, since the SCV valve is being opened, the EGR is not executed.

In this state, when the operating state enters the SCV valve closing region due to the decrease of the rotation speed, the SCV valve closing condition is satisfied,
Even in this case, the SCV is not immediately closed, and the EGR is started at the same time when the SCV closing condition is satisfied (section II).
. Then the time T ₂ 'EGR when elapsed is stopped again (section III), then the predetermined time (SCV closed condition is satisfied from the time T _1') has elapsed after SCV is closed (interval IV).

The above operation will be described with reference to the output torque curve of FIG. 3. Before the SCV valve closing condition is satisfied (FIG. 4, section I), the engine operating state is at point II on the solid line C in FIG. Next, the EGR is started, and when the time T ₂ ′ has elapsed (the state at the end of section II in FIG. 4,), the operating state shifts to the point II ′ on the dotted line D. That is, in this embodiment, the time T ₂ ′ is a time sufficient for the effect of EGR ON to appear and the operating state to shift from the solid line A to the dotted line D (usually, the time T ₂ ′ is about 1 to 2 seconds. ).

When the time T ₂ ′ has elapsed, the EGR is stopped (section III in FIG. 4,), and when the predetermined time (T ₁ ′ after the SCV closing condition is satisfied) has elapsed, the SCV is then closed (FIG. 4, FIG. 4). Section IV). Here, the time T ₁ 'is the time when the torque increasing effect due to the EGR stop begins to appear, and usually T ₁ ' = T ₂ '
It is about +1 second. Therefore, the torque decrease due to the SCV valve closing and the torque increase due to the EGR stop can be obtained almost at the same time,
The operating point shifts from the point II ′ on the dotted line D to the point I on the solid line A, and the torque change is smaller than that in the case where the point II directly shifts to the point I.

Therefore, the change in the throttle opening TA (accelerator pedal depression amount) in FIG. 5 is gentler than in the case where EGR is not performed (dotted line in FIG. 5), and does not give the driver a large discomfort. 6 and 7 are flowcharts showing an example of the SCV opening / closing control operation. This routine is EC
It is executed by U50 (FIG. 1) at regular time intervals (for example, every 12 milliseconds).

When the routine starts in FIG.
At Step 101, it is determined whether the SCV is closed or not,
When the valve is closed, the SCV valve opening condition (Fig. 2) is met.
It is determined whether or not (step 103). Opening valve
If the condition is satisfied, the counter C is determined in step 109.
_EGRAnd C_EGRIs the predetermined value C₁
(C₁Is time T in FIG.₁Number of routine executions corresponding to
Open the EGR valve (Fig. 1, 35) until it reaches
To EGR (step 105, 10
7), then C_EGRIs C₁SCV is opened
(Steps 105, 111). In this state
Pass C_EGRIs the predetermined value C₂(C₂Is time T in FIG. ₂Phase
When the number of times the routine is executed is reached (step 11)
3), EGR is stopped (step 115), counter C
_EGRReset (step 117) and end the routine
To do. Also, in step 103, the SCV valve opening condition is not satisfied.
If not, set the EGR valve (Fig. 1, 35) to the engine load condition.
Set to a predetermined opening (step 119),
Counter C_EGRReset (step 117)
Finish Chin.

If the SCV is not in the valve closed state in step 101, that is, if it is in the valve open state, the routine proceeds to step 122 in FIG. 7 and it is determined whether or not the SCV valve closing condition is satisfied. If the valve closing condition is satisfied, the counter C _EGR is used in the same manner as described above (step 128), and after the valve closing condition is satisfied, C _EGR becomes a predetermined value C ₂ '(C ₂ ' is set to the time T ₂ 'in FIG. 5). EGR is carried out until the number of times corresponding to the routine execution is reached (steps 124, 126), and EGR is stopped after a lapse of time T ₂ '(steps 124, 130).

Next, in this state, C _EGR is a predetermined value C ₁ '(C
_When 1'reaches the number of times of routine execution corresponding to the time T ₁ 'in FIG. 5, SCV is closed (steps 132 and 134), the counter C _EGR is reset and the routine ends (step 136). If the valve closing condition is not satisfied in step 122, the EGR is not executed when the SCV is opened in this embodiment, so the routine proceeds to step 138, the EGR is stopped, the counter C _EGR is reset (step 136), and the routine is ended. To do.

In this embodiment, the EGR control is always performed at the time of the SCV opening / closing operation. However, the EGR control is performed when the changing speed of the throttle valve opening is a predetermined value or more (that is, sudden acceleration or rapid deceleration). Alternatively, the SCV opening / closing operation may be performed at the same time when the SCV opening / closing condition is satisfied.
Similarly, in this embodiment, the EGR valve is ON when the SCV is opened / closed.
Although the ON / OFF control is performed, the EGR valve opening may be gradually changed to continuously increase or decrease the EGR amount to further alleviate the torque change due to the execution of EGR.

[0038]

As described above, the variable intake control device according to the present invention controls the EGR at the same time as the SCV opening / closing operation, thereby preventing the engine output torque from abruptly changing due to the SCV opening / closing without deteriorating the fuel consumption, and thereby improving the driving feeling. Has the effect of preventing the deterioration of

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of an internal combustion engine to which the present invention is applied.

FIG. 2 is a diagram showing opening / closing conditions of a swirl control valve.

FIG. 3 is a diagram showing changes in engine output torque due to opening / closing of a swirl control valve and execution of EGR.

FIG. 4 is a diagram showing EGR control at the time of a swirl control valve opening operation and a temporal change of each operation parameter.

FIG. 5 is a view similar to FIG. 4 when a swirl control valve is closed.

FIG. 6 is a flowchart showing an example of a swirl control valve opening / closing control operation.

FIG. 7 is a flowchart showing an example of a swirl control valve opening / closing control operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Cylinder head 12 ... Combustion chamber 14a ... Swirl port 14b ... Straight port 16a, 16b ... Exhaust port 20 ... Intake passage 20a, 20b ... Branch passage 26 ... Fuel injection valve 27 ... Communication passage 28 ... Partition wall 32 ... Swirl control valve 35 … EGR valve 38… EGR port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location F02M 25/07 550 G 8923-3G R 8923-3G

Claims (1)

[Claims] 1. A swirl control valve is provided in an intake passage, and the swirl control valve is closed under a predetermined condition to generate an intake swirl in a combustion chamber, and exhaust gas recirculation is performed when the swirl control valve is closed. In the variable intake control device for an internal combustion engine, which reduces the exhaust gas recirculation amount when the swirl control valve is opened, the exhaust gas is reduced in a direction that reduces a change in output torque due to opening and closing of the swirl control valve when the swirl control valve is opened and closed. A variable intake control device for an internal combustion engine, characterized by controlling a gas recirculation amount.