JPH06264751A - Internal combustion engine intake system - Google Patents

Abstract

(57) [Summary] [Purpose] To ensure a gas flow in the combustion chamber that suits the operating conditions even when the engine temperature is low. In an internal combustion engine having an air assist injector 13 installed in an intake system and having a swirl control valve 15 provided with a predetermined cutout, a means for detecting an operating condition of the engine and a fully open swirl control valve 15, The actuator 22 that can be driven to each of the half-open and fully-closed positions and the air assist of the air assist injector 13 in the engine low load region where the engine temperature is lower than a predetermined value are performed. The air assist of the air assist injector 13 is stopped from the engine low load region above a predetermined value to the partial load region,
The swirl control valve 15 is provided at a half-open position, and a control means 26 for controlling the swirl control valve 15 at a fully open position is provided in an operating region other than these, and at least the inner surface of the intake passage 11 with respect to the non-notched side of the swirl control valve 15 is swirled. Control valve 1
The valve 5 is formed from the fully closed position to the half open position along the rotational trajectory of the valve 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an internal combustion engine.

[0002]

2. Description of the Related Art An intake system for an internal combustion engine is provided with a swirl control valve near an intake port and an air assist injector for introducing auxiliary air (assist air) near a fuel injection port.

When the swirl control valve is closed,
The intake air flows in only through a predetermined notch formed in the valve, and a strong swirl (gas flow) is generated in the combustion chamber.

Assist air is guided to the vicinity of the fuel injection port of the air assist injector from the upstream side of the throttle valve via the air assist passage to promote atomization of the fuel spray.

By strengthening the gas flow and promoting the atomization of fuel in this way, lean combustion is performed while suppressing an increase in NOx (see Japanese Utility Model Laid-Open No. 1-76558, etc.).

[0006]

However, in such a conventional device, since the size of the notch of the swirl control valve is fixed, it is not always required in a wide operating range of the engine from a low load region to a high load region. No gas flow is obtained.

For example, if the notch of the swirl control valve is large, the cooling water temperature of the engine is low, and when air assist is performed from the air assist injector, the intake speed is low even in the low load region even when the valve is fully closed. As a result, the desired gas flow cannot be maintained.

If the notch of the swirl control valve is small, intake air will flow only from the notch when the valve is fully closed in the partial load range when warming up.
It becomes resistance for that amount. At this time, if the valve is fully opened, the gas flow extremely decreases.

On the other hand, regardless of the size of the notch, when the swirl control valve is opened, intake air flows in not only from the notch but also around the valve. Therefore, when the valve is open, the flow of intake air is dispersed even if the opening ratio of the valve is reduced, and it is difficult to obtain a gas flow suitable for the operating range.

Therefore, there is a limit to the improvement of combustion.

An object of the present invention is to solve such a problem.

[0012]

According to a first aspect of the present invention, an operating condition of an engine is detected in an internal combustion engine having an air assist injector installed in an intake system and a swirl control valve provided with a predetermined notch. Means and
An actuator that can drive the swirl control valve to each position of fully open, half open, and fully closed, and air assist the air assist injector to the engine low load range where the engine temperature is lower than the specified value, and put the swirl control valve to the fully closed position. Control to stop the air assist of the air assist injector from the engine low load range where the engine temperature is above a predetermined value to the partial load range, and control the swirl control valve to the half open position and the swirl control valve to the fully open position in other operating ranges. And the inner surface of the intake passage for at least the non-notched side of the swirl control valve is formed from the fully closed position to the half open position of the swirl control valve along the rotational trajectory of the valve.

According to a second aspect of the present invention, the actuator of the swirl control valve is provided with a temperature-sensitive thermowax that regulates the fully closed position.

[0014]

In the first aspect of the invention, when air assist is performed from the air assist injector, the swirl control valve is fully closed in the low load region of the engine, and the swirl control valve is fully opened in the other load regions. That is, by atomizing the fuel by air assist, and by making the intake air flow into the low load region through the small notch of the swirl control valve, a predetermined gas flow is generated in the combustion chamber, but not so much gas flow is required. In the operating range, fully open the swirl control valve to reduce the intake resistance.

When the engine temperature is high and the air is not assisted, the swirl control valve is half-opened in the partial load range or less, and fully opened in the other high load range. This ensures the required gas flow from the low load range to the partial load range, and allows the intake air to smoothly flow into the high load range.

In this case, the inner surface of the intake passage for at least the non-notched side of the swirl control valve is formed along the rotation locus of the swirl control valve from the fully closed position to the half open position of the swirl control valve, that is, below the half open position of the swirl control valve. Then, all the intake air flows from the notch side. Therefore, while increasing the opening ratio of the swirl control valve, the intake air flows in only from one direction, so that the desired gas flow is ensured from the low load area while maintaining the smooth intake air flow in the partial load area. .

A second aspect of the present invention regulates the fully closed position of the swirl control valve by a thermowax that responds to the engine temperature, that is, maintains the fully closed position of the swirl control valve when the engine temperature is extremely low, and responds to an increase in the engine temperature. Open the swirl control valve, and keep the swirl control valve in the half-open position when the engine temperature is the specified value.

As a result, the swirl control valve can be fully opened and closed. Further, in this case, even when the engine temperature is low, the opening ratio of the swirl control valve increases as the temperature rises, and a smooth inflow of intake air is secured.

[0019]

1 to 3 show an embodiment of the present invention.
Reference numeral 10 is an engine body, 11 is an intake passage, and 12 is a throttle valve. The air assist injector 13 is installed on the intake port 14 side of the intake passage 11, and the swirl control valve (SCV) 15 is located immediately upstream of the intake port 1.
It is installed in the vicinity of 4.

The air assist injector 13 is provided with an air assist passage 16 for guiding auxiliary air from the upstream side of the throttle valve 12 to the vicinity of the fuel injection port.
A cutoff solenoid 17 is installed at 6.

When the cutoff solenoid 17 is opened,
The assist air from the air assist passage 16 promotes atomization of the fuel spray from the air assist injector 13.

The swirl control valve 15 is formed with a notch 18 of a predetermined size on the air assist injector 13 side, and the inner surface of the intake passage 11 on the non-notch side is centered around the pivot shaft 19 of the swirl control valve 15. 15
From the fully closed position (shown by the solid line in FIG. 2) to the half open position (shown by the dotted line in FIG. 2) on the curved portion 20 along the rotation locus of the swirl control valve 15.

Even if the swirl control valve 15 is opened, the intake air flows in only from the cutout portion 18 and the periphery of the cutout side valve as shown in FIG.

In this case, as shown in FIGS. 5 and 6, all the inner surfaces of the intake passage 11 with respect to the non-notched portion of the swirl control valve 15 are covered with the swirl control valve 15.
The curved portion 20 may be formed along the rotation locus of the swirl control valve 15 from the fully closed position to the half open position.

The rotating shaft 19 of the swirl control valve 15 is connected to a diaphragm device 22 via a lever 21. A suction negative pressure is introduced into the negative pressure chamber of the diaphragm device 22 from the downstream side of the throttle valve 12 via the negative pressure passage 23, and a duty solenoid 24 for controlling dilution of the negative pressure is installed in the middle of the negative pressure passage 23. .

By controlling the negative pressure to the diaphragm device 22 via the duty solenoid 24, the swirl control valve 15 is driven to an arbitrary opening degree from the fully closed position to the fully open position.

Here, the swirl control valve 15
The size of the cutout portion 18 is about 10 at the fully closed position.
%, And swirl control valve 15
The half open position is set so that the aperture ratio is about 40%.

As the engine operating condition detecting means, an air amount sensor (not shown) for detecting the intake air amount of the engine, a throttle opening sensor for detecting the opening of the throttle valve 12, and an engine cooling water temperature (engine temperature) are used. A water temperature sensor 25 for detecting is provided.

These signals are sent to the control unit 26.
Based on these signals, the control unit 26 controls the cutoff solenoid 17 and the duty solenoid 24, that is, the air assist of the air assist injector 13 and the opening of the swirl control valve 15.

Next, the control and operation will be described.

As shown in the flow chart of FIG. 7, first, the cooling water temperature Tw is read and compared with a predetermined value T ₁ (steps 101 and 102).

When the cooling step Tw is lower than the predetermined value T ₁ , the assist air valve (cutoff solenoid 1
Opens the 7), the intake air quantity Qa is compared with a predetermined value Q _1, if the intake air quantity Qa at this time is equal to or less than a predetermined value Q ₁ (low load), it closes the swirl control valve 15 fully, inhalation If the air amount Qa exceeds the predetermined value Q ₁ (more than the partial load range), the swirl control valve 15 is fully opened (steps 103 to 106, 113).

When the cooling water temperature Tw is equal to or higher than the predetermined value T ₁ ,
The assist air valve 17 is closed (air assist is stopped), and if the intake air amount Qa is equal to or less than the predetermined value Q ₂ (partial load range or less) at this time, the swirl control valve 15 is half-opened to set the intake air amount Qa to the predetermined value. if it exceeds the value Q ₂ (high load region), to fully open the swirl control valve 15 (step 107～110,113).

FIG. 8 shows control conditions and control areas.

When the throttle valve 12 is suddenly opened and suddenly accelerated, the swirl control valve 15 is fully opened (steps 111 to 113 in FIG. 7).

That is, when the temperature of the cooling water is low, air assist is performed from the air assist injector 13.

At this time, in the low load range, the swirl control valve 15 is fully closed, and intake air flows in through the small cutout portion 18.

Therefore, the air assist injector 13
The atomization of the fuel from the fuel is promoted, the gas flow in the combustion chamber is strengthened, and good combustion is maintained by the atomization of the fuel and the gas flow, and the exhaust emission at low temperature is reduced.

Immediately after the cold start, the three-way catalyst installed in the exhaust system is not sufficiently activated. Therefore, the reduction of the emission flowing out from the exhaust valve at this time has a great effect as compared with after the warm-up. In this case, an aperture ratio (notch 18) of about 10% is appropriate in relation to the air assist amount.

Outside the low load range, the swirl control valve 15 is fully opened and therefore does not act as a resistance to intake air.

On the other hand, when the warming-up progresses and the cooling water temperature exceeds the predetermined value, the air assist from the air assist injector 13 is not performed.

At this time, below the partial load range, the swirl control valve 15 is half-opened and the opening ratio is set to about 40%.

Therefore, the required gas flow is secured in the combustion chamber, and good combustion is obtained from the low load region to the partial load region.

FIG. 9 shows the relationship between the opening ratio of the swirl control valve 15 and the engine output.
In this case, it is possible to operate in almost all areas, especially at medium speeds and below, torque that is almost the same as full open torque (when the swirl control valve is fully open) is maintained, and 80% or more of the maximum output is covered even at high speeds. . When the opening ratio is 30% or less, the torque decreases from around the middle load, so that the swirl control valve 15 is opened and closed more frequently in the practical operating range, which causes a deterioration in drivability such as a step difference in torque.

As a result, lean combustion is possible without impairing drivability, fuel consumption is improved, and exhaust emission is sufficiently reduced.

In the high load region, the swirl control valve 15 is fully opened and, of course, high output is secured.

From the low load area to the partial load area,
By increasing the EGR rate of a known EGR (exhaust gas recirculation) device, fuel efficiency is further improved.

Further, when the swirl control valve 15 is opened, in the conventional structure, intake air flows in not only from the cutout portion but also around the valve. Therefore, even if the opening ratio is lowered from the low load region to the partial load region, Although the required gas flow cannot be obtained, in this case, as shown in FIGS. 2 to 6, the swirl control valve 15 is provided on the inner surface of the intake passage 11 with respect to the non-notched side or the notched portion from the fully closed position to the half-opened position. Since it was formed along the rotation trajectory of, within half opening,
The intake air flows in only from the cutout portion 18 or one direction around the cutout side.

Therefore, the aperture ratio is 40 as shown in FIG.
%, The swirl ratio obtained in the conventional structure is halved compared to the ideal shape, but a good swirl ratio is obtained in the shapes of FIGS. 2 to 4, and further, in FIGS. A swirl ratio close to the ideal is secured for the thing. As a result, at the opening ratio of 40% to obtain a sufficient torque, the gas flow meeting the demand is maintained.

FIG. 11 shows another embodiment of the present invention, in which the lever 21 of the rotary shaft 19 of the swirl control valve 15 is provided with a thermowax 30 for restricting the fully closed position.

A pipe 31 is provided around the thermowax 30.
The cooling water for the engine is introduced through the thermowax 30 in accordance with the rise in the cooling water temperature, and the stay 32 at the tip end is expanded.
Is extended. When the cooling water temperature is extremely high, the initial fully closed position of the swirl control valve 15 is maintained, the fully closed position is changed to the open side as the cooling water temperature rises, and when the cooling water temperature reaches a predetermined value, it is switched to the half open position.

Reference numeral 22 is a diaphragm device for driving the swirl control valve 15 via the lever 21.

That is, as shown in FIG. 12, the swirl control valve 15 is opened in response to the rise of the cooling water temperature, and the swirl control valve 15 is set to the half open position when the cooling water temperature is equal to or higher than a predetermined value (however, the diaphragm device 2
2 when not driven).

According to this, the swirl control valve 15 can be driven only by fully closing and opening, and the duty solenoid is not required. Further, when the cooling water temperature is not so low, the aperture ratio is increased and the intake resistance is suppressed.

[0055]

As described above, the first aspect of the present invention provides the intake system with
In addition to installing an air-assist injector, in an internal combustion engine that has a swirl control valve with a predetermined cutout, it is possible to drive the swirl control valve to the fully open, half open, and fully closed positions as well as the means for detecting the operating conditions of the engine. The air assist of the air assist injector is performed in the engine low load range where the engine temperature is lower than the specified value, the swirl control valve is in the fully closed position, and the engine temperature is above the specified value in the engine low load range to the partial load range. The air assist of the air assist injector is stopped, the swirl control valve is set to the half open position, and the control means for controlling the swirl control valve to the fully open position is provided in the operating range other than these, and at least the non-notched side of the swirl control valve is provided. Swirl control the inside of the intake passage Since the valve is formed along the rotational path of the valve from the fully closed position to the half-opened position, it is possible to maintain good combustion by maintaining gas flow in the combustion chamber that suits the operating conditions even when the engine temperature is low. Emissions can be reduced sufficiently and fuel consumption can be greatly improved.

Further, according to the second aspect of the present invention, since the temperature sensitive thermowax for restricting the fully closed position is provided in the actuator of the swirl control valve, the swirl control valve can be driven easily.

[Brief description of drawings]

FIG. 1 is a sectional view of an example.

FIG. 2 is a sectional view of a main part.

FIG. 3 is a vertical sectional view thereof.

FIG. 4 is an explanatory diagram of the operation.

FIG. 5 is a cross-sectional view of main parts of another embodiment.

FIG. 6 is a sectional view taken along the line AA.

FIG. 7 is a control flowchart.

FIG. 8 is a setting diagram of control conditions and control areas.

FIG. 9 is a graph showing the relationship between opening ratio and engine output.

FIG. 10 is a graph showing the relationship between the aperture shape and the swirl ratio.

FIG. 11 is a sectional view of an essential part of another embodiment.

FIG. 12 is a setting diagram of the control condition and control area.

[Explanation of symbols]

 11 Intake passage 12 Throttle valve 13 Air assist injector 14 Intake port 15 Swirl control valve 16 Air assist passage 17 Cut-off solenoid 18 Cutout portion 20 Bending portion 22 Diaphragm device 23 Negative pressure passage 24 Duty solenoid 25 Water temperature sensor 26 Control unit 30 Thermo wax

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display area F02M 69/00

Claims (2)

[Claims] 1. An internal combustion engine having an air assist injector installed in an intake system and having a swirl control valve provided with a predetermined notch, means for detecting an operating condition of the engine, and a fully open or half open swirl control valve. , The actuator that can be driven to the fully closed position and the air assist of the air assist injector in the engine low load range where the engine temperature is lower than the specified value, the swirl control valve is set to the fully closed position, and the engine temperature is above the specified value. From the engine low load range to the partial load range, the air assist of the air assist injector is stopped, the swirl control valve is set to the half open position, and the control means to control the swirl control valve to the fully open position in the other operating range, and the swirl Intake air to at least the non-notched side of the control valve An intake device for an internal combustion engine, wherein an inner surface of the passage is formed along a rotational locus of the swirl control valve from a fully closed position to a half open position. 2. The intake system for an internal combustion engine according to claim 1, wherein the actuator of the swirl control valve is provided with a temperature-sensitive thermowax that regulates a fully closed position.