JP2737494B2 - Opening control device for swirl control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a swirl control valve in which a part of an intake passage is closed in order to strengthen a swirl in a combustion chamber, and more particularly to an opening control device for the swirl control valve.

[0002]

2. Description of the Related Art An exhaust gas recirculation device for recirculating a part of exhaust gas to an intake system for reducing NOx discharged from an internal combustion engine is known as a very effective means. In this exhaust gas recirculation device, it is necessary to appropriately control the exhaust gas recirculation rate (EGR rate), and various types have been proposed to obtain desired characteristics. Most commonly, a negative pressure taken out from a negative pressure outlet opening on the upstream side, that is, a so-called VC negative pressure, is used as a basic operating source of the exhaust gas recirculation control valve (for example, Japanese Patent Laid-Open No. 55-161951). No., JP-A-55-137348
Reference).

On the other hand, when the exhaust gas is recirculated, the combustion state of the engine tends to be unstable, and the operability deteriorates particularly in a partial load region. Therefore, a swirl control valve that strengthens swirl in the combustion chamber by closing a part of the intake passage to stabilize combustion may be used together with the exhaust gas recirculation device. This swirl control valve has, for example, a configuration in which one of a pair of intake ports is closed in an intake two-valve engine, a configuration in which a cutout portion is provided in a part of a butterfly valve type valve body to bias the intake air flow, and the like. However, a negative pressure diaphragm type actuator is generally used as an actuator for driving the valve. This actuator is disclosed in
As disclosed in Japanese Patent Publication No. 107019 and Japanese Patent Publication No. 58-9247, a negative pressure in an intake pipe downstream of a throttle valve is introduced as a control negative pressure. That is, the swirl control valve is closed in a low-to-medium load region where the intake pipe negative pressure is strong, and the swirl control valve is opened in a high load region because the negative pressure is weakened.

By providing the above-described swirl control valve, the allowable limit of the exhaust gas recirculation rate (the maximum exhaust gas recirculation rate within a range that does not cause deterioration in operability) is determined by the swirl control as shown by a dashed line in FIG. It is higher than that without a valve (see broken line). The actual exhaust gas recirculation rate is set so as not to exceed this allowable limit as shown by the solid line in FIG. Note that this example is based on a so-called BPT type exhaust gas recirculation device, and the exhaust gas recirculation rate is kept constant in a region above a certain load.

[0005]

The above-described conventional swirl control valve is fully closed in a low-to-medium load region where the negative pressure of the intake pipe exceeds the set load of the actuator. On the other hand, the pumping loss increases, and the fuel consumption rate of the engine deteriorates. That is, unnecessarily closing the swirl control valve to strengthen the swirl is not preferable in terms of improving fuel efficiency.

However, since the exhaust gas recirculation rate characteristic shown by the solid line in FIG. 2 and the allowable limit characteristic when the swirl control valve is fully closed shown by the dashed line are not necessarily similar, if the exhaust gas recirculation rate characteristic is set within the allowable limit, In a low load region including idle, the swirl control valve operates excessively, resulting in unnecessary pumping loss. That is, in the above-mentioned conventional one,
The pumping loss could not be reduced and the fuel efficiency could not be improved sufficiently, and there was room for further improvement.

[0007]

In view of the above, a swirl control valve opening control device according to the present invention suppresses pumping loss by keeping the swirl control valve closing operation to a necessary minimum. The VC negative pressure taken from a position slightly upstream from the fully closed position of the throttle valve is used as a basic operating source of the exhaust gas recirculation control valve, and the exhaust gas recirculation rate increases as the VC negative pressure increases.
And exhaust gas recirculation device for opening operation of the exhaust the reflux control valve so as to rise, located downstream from the throttle valve, and a swirl control valve to enhance the swirl of the combustion chamber by closing a part of the intake passage, is introduced in response to the negative pressure that
A negative pressure actuator for closing the swirl control valve so as to strengthen the swirl as the negative pressure increases, wherein the VC negative pressure taken from the same position as the negative pressure for the exhaust gas recirculation device is provided. Is introduced as the control negative pressure of the actuator.

[0008]

In the above configuration, a VC negative pressure having substantially the same characteristics is supplied to the exhaust gas recirculation device and the swirl control valve actuator. Accordingly, in a region where the VC negative pressure is weak and the exhaust gas recirculation rate is suppressed to be low, the opening degree of the swirl control valve increases accordingly. That is, the opening of the swirl control valve is regulated so that the allowable limit characteristic of the exhaust gas recirculation rate conforms to the actual exhaust gas recirculation rate characteristic, thereby preventing unnecessary pumping loss.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is an explanatory view showing the structure of an embodiment of the present invention, wherein 1 denotes an internal combustion engine, 2 denotes an intake passage, and 3 denotes an exhaust passage. A throttle valve 4 is provided on the inlet side of the intake passage 2, more specifically, a collector portion 2 a in which the intake passages 2 of the respective cylinders are gathered. A negative pressure outlet 5 is formed in the passage wall near the throttle valve 4. Have been. The negative pressure outlet 5 is provided at a position slightly upstream of the fully closed position of the throttle valve 4 and relatively downstream with the opening operation of the throttle valve 4. A swirl control valve 7 for enhancing the swirl in the combustion chamber 6 is provided downstream of the throttle valve 4 in the intake passage 2. This swirl control valve 7
Is provided for each cylinder, and has, for example, a butterfly valve type configuration that opens and closes one of intake ports provided in pairs for each cylinder. A diaphragm type negative pressure actuator 8 is provided so as to open and close the swirl control valve 7. The actuator 8 closes the swirl control valve 7 when a negative pressure is introduced into the negative pressure chamber 8a, and keeps the swirl control valve 7 fully open when no negative pressure is introduced. As shown in FIG. 3, the opening degree continuously changes according to the strength of the negative pressure, and is fully closed at a certain negative pressure or more.

On the other hand, in this embodiment, a so-called BPT type exhaust gas recirculation device is used as the exhaust gas recirculation device. This means that an exhaust gas recirculation control valve 12 that opens and closes an exhaust gas recirculation passage 11 that extends from the exhaust gas passage 3 to the collector section 2a, and a negative pressure introduced into a negative pressure chamber 12a of the exhaust gas recirculation control valve 12
2b and a negative pressure control valve 13 for correcting based on the exhaust pressure on the upstream side. That is, the negative pressure chamber 12a communicates with the negative pressure outlet 5 through the negative pressure passage 15 having the orifice 14, and the orifice 14 of the negative pressure passage 15, the exhaust gas recirculation control valve 12, One end of the air introduction passage 16 is connected between the two. The other end of the atmosphere introduction passage 16 is connected to the atmosphere chamber 13a of the negative pressure control valve 13.
The pressure chamber 13b of the negative pressure control valve 13 and the exhaust pressure chamber 12c upstream of the valve element 12b of the exhaust gas recirculation control valve 12 are opened and closed by a diaphragm 17 inside the exhaust pressure passage 1.
It is communicated at 8. An orifice 19 is provided upstream of the exhaust recirculation passage 11 in the exhaust pressure chamber 12c.

The orifice 14 of the negative pressure passage 15
One end of the swirl control valve negative pressure passage 20 is connected to the negative pressure outlet 5 side. The other end of the swirl control valve negative pressure passage 20 is connected to the negative pressure chamber 8 a of the swirl control valve actuator 8. Further, an EGR cut solenoid valve 21 that opens to introduce air by a control signal from a control unit (not shown) is provided in the middle of the swirl control valve negative pressure passage 20.

In the above structure, a negative pressure having a characteristic shown by a solid line in FIG. That is, the negative pressure is 0 near idle where the negative pressure outlet 5 is relatively upstream of the throttle valve 4, and
Further, when the throttle valve 4 is relatively downstream, the negative pressure suddenly increases to a certain level with the opening operation of the throttle valve 4, and thereafter gradually increases.

In the exhaust gas recirculation device, basically, the exhaust gas recirculation control valve 12 is opened using the above-mentioned VC negative pressure as an operation source, and the exhaust gas is recirculated. That is, the throttle valve 4
Is gradually opened, the exhaust gas recirculation rate increases with characteristics substantially in line with the characteristics of the VC negative pressure until a predetermined exhaust gas recirculation ratio is reached. Thereafter, when a predetermined exhaust gas recirculation rate is reached, the exhaust pressure chamber 1
The atmosphere is introduced into the atmosphere introduction passage 16 due to the decrease in the exhaust pressure of 2c, and the VC negative pressure is weakened. Therefore, an exhaust gas recirculation rate characteristic as shown by a solid line in FIG. 2 is obtained.

On the other hand, since the opening of the swirl control valve 7 is also controlled by the above-mentioned VC negative pressure, the opening characteristics shown by the two-dot chain line in FIG. 4 are obtained. That is, since the VC negative pressure is 0 near the idling state, the VC negative pressure is kept at the fully open state, and the VC negative pressure gradually closes with the rise of the VC negative pressure, and is fully closed when the VC negative pressure changes gradually.
In the case where control is performed by the intake pipe negative pressure as in the past,
As shown by the one-dot chain line in FIG. 4, the vehicle is fully closed including the vicinity of the idle.

As described above, as a result of the swirl control valve 7 being opened to a large extent in the low load range, the pumping loss of the swirl control valve 7 is reduced. Here, since the swirl control valve 7 is not fully closed, the swirl is weakened to some extent, and the allowable limit of the exhaust gas recirculation rate is lower than the characteristic at the time of the fully closed state. Therefore, as the allowable limit of the exhaust gas recirculation rate, a characteristic similar to the actual exhaust gas recirculation rate characteristic can be obtained as shown by a two-dot chain line in FIG. Accordingly, the pumping loss can be reduced in a region shown by hatching in FIG. 2, and at the same time, the exhaust gas recirculation rate becomes equal to or less than an allowable limit in consideration of a substantially constant margin, so that no deterioration in drivability is caused. In other words, the swirl enhancement by the swirl control valve 7 is minimized in a form corresponding to the actual exhaust gas recirculation rate, and unnecessary pumping loss can be avoided.

When the EGR cut solenoid valve 21 is turned on at a low temperature or the like, the atmosphere is introduced into both the negative pressure passage 15 and the negative pressure passage 20 for the swirl control valve.
Therefore, the exhaust gas recirculation control valve 12 is closed and the exhaust gas recirculation is stopped, and the swirl control valve 7 is fully opened, which also prevents unnecessary pumping loss.

In the above embodiment, a single negative pressure outlet 5
Since exactly the same negative pressure taken out in step (1) is introduced into the exhaust gas recirculation device and the swirl control valve actuator 8, V
Even if the characteristics of the C negative pressure (see the solid line in FIG. 4) vary somewhat, the opening degree characteristics of the swirl control valve 7 also change at the same time as the actual exhaust gas recirculation rate changes. Therefore, a desired margin can be secured between the allowable limit and the actual exhaust gas recirculation rate, and the deterioration of the operability caused by the characteristic variation of the VC negative pressure is reliably avoided.

It should be noted that a pair of negative pressure outlets 5 are arranged side by side at the same position in the intake passage 2 without sharing the negative pressure outlet 5 as in the above embodiment, and the exhaust recirculation device and the actuator for the swirl control valve are provided. 8 may be configured to introduce a negative pressure.

[0020]

As is clear from the above description, according to the swirl control valve opening control apparatus of the present invention, the swirl control valve closing operation is performed with a minimum necessary value corresponding to the actual exhaust gas recirculation rate characteristic. The pumping loss can be suppressed and the fuel consumption rate can be improved. Moreover, the stabilization of the combustion by the strengthening of the swirl is performed in a form corresponding to the actual exhaust gas recirculation rate, so that it is possible to reliably avoid the deterioration of the operability due to the exhaust gas recirculation.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing an embodiment of an opening control device according to the present invention.

FIG. 2 is a characteristic diagram showing a relationship between exhaust gas recirculation rate characteristics and their allowable limits.

FIG. 3 is a characteristic diagram showing an opening degree characteristic of the swirl control valve and the exhaust gas recirculation control valve with respect to a negative pressure.

FIG. 4 is a characteristic diagram showing a characteristic of a VC negative pressure and an opening degree characteristic of the swirl control valve based on the characteristic.

[Explanation of symbols]

 4 ... Throttle valve 5 ... Negative pressure outlet 7 ... Swirl control valve 8 ... Diaphragm type negative pressure actuator 12 ... Exhaust recirculation control valve

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 25/07 570 F02M 25/07 570Z 580 580F

Claims (1)

(57) [Claims] 1. A a VC negative pressure taken out from the slightly upstream side of the position from the fully closed position of the throttle valve and the basic source of operation of the exhaust gas recirculation control valve, instead of the exhaust as the VC negative pressure increases
An exhaust gas recirculation device that opens the exhaust gas recirculation control valve so that the flow rate increases, and a swirl in the combustion chamber that is located downstream of the throttle valve and closes a part of the intake passage to enhance swirl. The swirl control valve and the swirl are strengthened as the negative pressure increases according to the introduced negative pressure .
And a negative pressure actuator for closing the swirl control valve.
A swirl control valve opening control device, wherein a VC negative pressure taken from the same position as the negative pressure for the exhaust gas recirculation device is introduced as a control negative pressure for the actuator.