JPH0232856Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The present invention relates to a control device for an exhaust gas recirculation system that recirculates a portion of engine exhaust gas to the intake system to reduce _NOx in the exhaust gas. be.

(Prior Art) Conventionally, as an exhaust recirculation system for this type of engine, as disclosed in Japanese Patent Application Laid-Open No. 57-143126, etc., the intake passage immediately upstream of the intake valve is connected to a main intake passage provided with a throttle valve whose opening degree increases as the main intake passage moves to the main intake passage;
The exhaust gas recirculation passage is separated into a sub-intake passage for light loads to generate intake swirl inside the cylinder, and the downstream end of the exhaust recirculation passage is opened in the sub-intake passage, so that when the engine is running at low speed and under low load, part of the exhaust gas is It is known that the exhaust gas is caused to flow from the recirculation passage into the combustion chamber via the sub-intake passage.

(Problem to be Solved by the Invention) However, in the above-mentioned conventional method, since the recirculated exhaust gas is mixed into the air-fuel mixture flowing at a high flow rate through the sub-intake passage, the recirculated exhaust gas cannot be mixed well with the air-fuel mixture. However, due to layout constraints such as avoiding interference with the cooling water passage in the cylinder head, it is necessary to limit the exhaust outlet at the downstream end of the exhaust recirculation passage to an upstream position relatively far from the intake valve in the auxiliary intake passage. Therefore, it takes time for the recirculated exhaust gas to substantially flow into the combustion chamber. Therefore,
Problems arise in the following cases. In other words, by setting the exhaust gas recirculation timing for supplying exhaust gas into the combustion chamber at a predetermined timing of the intake stroke of the cylinder, and distributing the recirculated exhaust gas unevenly and concentrated in the region where the combustion temperature is high in the combustion chamber, At exhaust gas recirculation amount
In order to effectively reduce _NOx , there is a possibility that the above-mentioned exhaust gas recirculation timing cannot be controlled accurately.

In addition, when the above-mentioned exhaust outlet is replaced with a sub-intake passage and opened into the main intake passage, the main intake passage is closed by the throttle valve when the engine is at low load, so that no exhaust gas recirculation occurs at low load. It becomes possible. Moreover, since the recirculated exhaust gas is mixed with the slow-flowing air-fuel mixture flowing through the main intake passage, there is still a delay in the timing of exhaust gas recirculation.

On the other hand, in the above-mentioned conventional example in which the intake passage upstream of the intake valve is divided into a sub-intake passage for swirl generation and a main intake passage, the flow velocity in the sub-intake passage is fast, so the intake flow rate is reduced. At a certain level, the strength of the intake swirl generated by the auxiliary intake passage becomes too strong, causing the air-fuel mixture to swirl toward the outer periphery of the cylinder and away from the spark plug, which is located approximately in the center of the cylinder. There was a problem that ignitability decreased.

Therefore, in order to prevent the ignitability from decreasing due to the increase in the strength of the intake swirl, if the passage area of the sub-intake passage is increased to suppress the intake air flow velocity,
Conversely, when the load of the engine is extremely low, the intake air flow velocity flowing through the sub-intake passage decreases, causing a problem that it becomes difficult to maintain an intake swirl of sufficient strength.

This idea was made in view of the above points,
The purpose of this is to cut out a specific part of the throttle valve installed in the main intake passage mentioned above, to give the intake air that passes through the cutout a flow velocity and directionality, and to mix the recirculated exhaust gas into the intake air. By doing so, the recirculated exhaust gas is supplied to the combustion chamber of the cylinder through the main intake passage, preventing a delay in the timing of exhaust recirculation, improving the ignitability of the air-fuel mixture in the combustion chamber, and reducing the swirl strength at extremely low loads. The aim is to achieve both security and security.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention is such that the intake passage near the intake valve is a secondary intake passage in which a throttle valve is arranged (the main The exhaust gas is divided into an intake passage (intake passage) and a primary intake passage (sub-intake passage) for generating an intake swirl in the cylinder, and supplies part of the exhaust gas into the cylinder through the intake passage. In an engine equipped with a supply means, a cutout portion for leaking intake air is formed on a side of the throttle valve corresponding to a tangential direction of the intake swirl caused by the primary intake passage, and The exhaust outlet of the exhaust supply means is opened in the side intake passage.

(Function) With the above configuration, the present invention supplies intake air mainly through the primary intake passage into the cylinder and generates a swirl of intake air within the cylinder during low to medium load of the engine with a small throttle valve opening. On the other hand, a part of the intake air is supplied into the cylinder through the notch of the throttle valve while increasing the flow velocity, and collides with the intake swirl from approximately the outside thereof.The collision of the intake air causes the swirl radius of the intake swirl to increase. By making the air-fuel mixture smaller and moving it closer to the spark plug located at the approximate center of the cylinder, ignitability is improved and the high-speed intake passing through the notch in the throttle valve is guided out from the exhaust outlet. By placing the recirculated exhaust gas on top of the exhaust gas, a delay in the timing of exhaust gas recirculation is prevented.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 shows the overall configuration of a first embodiment of the present invention, in which 1 is a cylinder head forming the upper part of a cylinder 2 of an engine, 3 is an intake port formed in the cylinder head 1, and 4 is an intake port formed in the cylinder head 1. An intake manifold is attached to communicate with a port 3, and the interior of this intake manifold 4 and the intake port 3 constitute an intake passage 5 that supplies intake air into the combustion chamber of the cylinder 2. The downstream end of the intake passage 5 is bifurcated, one of which is connected to a primary intake valve (not shown).
The two are connected to the combustion chamber of the cylinder 2 through a primary opening 5a opened and closed by a secondary intake valve (not shown) and a secondary opening 5b opened and closed by a secondary intake valve (not shown). , both openings 5a, 5
b is formed within one semicircular range of the cylinder 2.

Further, an exhaust port 7 is formed in the cylinder head 1 and constitutes an upstream end portion of an exhaust passage 6 for discharging exhaust gas in the combustion chamber.
The opening 6a to the combustion chamber is provided within the other semicircular area of the cylinder 2. 8 is an ignition plug provided approximately at the center of the cylinder 2.

1 at the intake port 3 of the intake passage 5 near the primary intake valve, that is, the intake passage 5.
The range from the portion communicating with the next side opening 5a to the downstream end within the intake manifold 4 is divided into a primary side intake passage 9 and a secondary side intake passage 10. A throttle valve 11 that throttles and opens/closes the secondary intake passage 10 is disposed in the middle of the secondary intake passage 10, and the throttle valve 11 is driven by an actuator (not shown) that operates according to the engine speed and load. When the engine is in a low speed, low load region, the opening degree is small, and as the engine moves to a high speed, high load region, the opening degree is controlled to increase.

On the other hand, the primary side intake passage 9 is arranged so as to bypass the throttle valve 11 of the secondary side intake passage 10, and its flow end opening 9a is connected to the intake passage 5 immediately upstream of the throttle valve 11. The downstream end openings 9b are located in the intake passage 5 immediately upstream of the primary opening 5a. Further, the passage area of the primary side intake passage 9 is set smaller than that of the secondary side intake passage 10, and as shown in the figure, as it goes from the upstream side to the downstream side, that is, it approaches the cylinder 2. It is formed in a curved shape so as to be shifted radially outward from the center of the cylinder 2 toward the primary side opening 5a, and the primary side intake passage 9
By causing the intake air flowing through the cylinder 2 to flow circumferentially into the cylinder 2 through the primary side opening 5a while increasing its flow velocity, a swirl K of intake air that swirls in the clockwise direction in the figure is generated in the cylinder 2. It is configured.

Further, the intake passage 5 and the exhaust passage 6 are communicated through an exhaust gas recirculation passage 12 for recirculating a part of the exhaust gas flowing through the exhaust passage 6 to the intake passage 5. In the middle of the exhaust gas recirculation passage 12, there is a diaphragm type exhaust recirculation valve 13 that throttles and opens and closes the exhaust gas recirculation passage 12 to control the amount of exhaust gas recirculation. A rotary valve 14 that can control timing and adjust its opening/closing timing is provided, and an exhaust passage 6
A part of the exhaust gas in the cylinder 2 is recirculated into the cylinder 2 via the exhaust gas recirculation passage 12 and the intake passage 5, and the amount of the exhaust gas recirculated is controlled to a predetermined amount by the exhaust gas recirculation valve 13, and the recirculation timing is controlled by a rotary control. The exhaust gas supply means 15 is configured to be controlled by the valve 14 at a predetermined timing of the intake stroke of the cylinder 2.

Furthermore, in the throttle valve 11 disposed in the secondary intake passage 10, the side corresponding to the tangential direction of the swirl K of intake air by the primary intake passage 9, that is, the primary intake passage is oriented in the downstream direction. A cutout portion 16 is formed in the side portion corresponding to the previously curved side by cutting out a predetermined range of the side portion,
When the engine is under low to medium load and the opening degree of the throttle valve 11 is small, intake air is leaked from the notch 16 and supplied to the combustion chamber of the cylinder 2.

Further, the two downstream of the notch 16 of the throttle valve 11 are
The next intake passage 10 has an exhaust outlet 12 as a downstream end of the exhaust gas recirculation passage 12 of the exhaust supply means 15.
a is open.

Therefore, in the above embodiment, when the throttle valve 11 has a small opening and the engine is under low to medium load, the air-fuel mixture flowing through the intake passage 5 mainly flows into the combustion chamber of the cylinder 2 through the primary intake passage 9. However, due to this flow of intake air, a swirl K is generated in the cylinder 2 in a clockwise direction in the figure. On the other hand, the intake passage 5
A part of the air-fuel mixture flowing through the throttle valve 11 passes through a notch 16 provided in the throttle valve 11, and is supplied into the cylinder 2 through the secondary intake passage 10 while being increased in flow velocity.

At this time, since the notch 16 is formed on the side of the throttle valve 11 corresponding to the tangential direction of the swirl K by the primary intake passage 9, the air-fuel mixture passing through the notch 16 is Notch part 16
It flows into the cylinder 2 through the primary side opening 5a located on the side corresponding to , and collides with the swirl K from the outside at a large angle within the cylinder 2. Due to the collision with the mixture flow from the notch 16, the turning radius of the swirl K becomes smaller, and the mixture approaches the vicinity of the ignition plug 8 located approximately at the center of the cylinder 2, causing the air-fuel ratio of the mixture around the ignition plug 8 to decrease. is enriched, thereby improving the ignitability of the engine.

In addition, the mixture flow passing through the notch 16 of the throttle valve 11 corrects the swirl locus of the swirl K and ensures the ignitability of the engine.
By increasing the passage area of the primary side intake passage 9, it is no longer necessary to reduce the swirl strength by suppressing the flow velocity of the air mixture flow, thus maintaining the swirl strength as good as usual when the engine is under extremely low load. can do.

Furthermore, when the engine is under low or medium load, the rotary valve 14 opens and the exhaust gas flows into the exhaust recirculation passage 12.
From the exhaust outlet 12a at the downstream end to the secondary intake passage 1
0, and the exhaust gas is carried by the high-velocity mixture flow passing through the notch 16 of the throttle valve 11 and becomes 1.
Since the exhaust gas is supplied into the cylinder 2 through the downstream opening 5a, the exhaust gas can be recirculated to the combustion chamber through the secondary intake passage 10, and the exhaust gas can be recirculated even when the engine is under low load. The recirculated exhaust gas can be quickly supplied into the cylinder 2, and the exhaust gas recirculation timing can be accurately controlled.

Note that when the engine is under high load, the opening degree of the throttle valve 11 increases, so that the air-fuel mixture mainly flows through the secondary intake passage 2 rather than the primary intake passage 9.
The air-fuel mixture flowing through the secondary intake passage 10 passes through the openings 5a and 5b on the primary and secondary sides and enters the cylinder 2.
flow inside.

2 and 3 show a second embodiment of the present invention (the same parts as in FIG. 1 are given the same reference numerals and detailed explanation thereof is omitted). Only one opening 5c of the passage 5' into the cylinder 2 is formed within one semicircular area of the cylinder 2, and a throttle valve is provided in the secondary intake passage 10 immediately upstream of the opening 5'c. The exhaust outlet 12a of the exhaust gas recirculation passage 12 is opened in correspondence with the notch 16 of the exhaust gas recirculation passage 11. The other parts are constructed in the same manner as in the first embodiment. In FIG. 2, 17 is a fuel injection valve that injects fuel into the intake passage 5' toward the opening 5'c to the cylinder 2, and 18 is a valve that opens and closes the opening 5'c of the intake passage 5'. 19 is an exhaust valve that opens and closes the opening 6a of the exhaust passage 6; 20 is a piston that reciprocates within the cylinder 2; and 21 is a combustion chamber formed within the cylinder 2.

Therefore, in this embodiment as well, the same effects as in the above embodiment can be achieved, and in addition, the exhaust outlet 12a is opened in the secondary intake passage 10 immediately upstream of the opening 5'c. Therefore, the fuel injection valve 17
The fuel injected toward the opening 5'c of the intake passage 5' and the downstream end opening 9b of the primary intake passage 9 in the vicinity thereof is transferred to the high-temperature recirculated exhaust gas led out from the exhaust outlet 12a. It has the advantage that it can be heated with gas heat to promote its vaporization and atomization.

(Effects of the invention) As described above, according to the invention, the intake passage near the intake valve is divided into the secondary intake passage in which the throttle valve is provided and the primary intake passage for generating intake swirl. In the engine, a notch is formed in the throttle valve to allow intake air to leak, and the high-velocity intake air passing through the notch collides with the intake swirl to deflect the intake swirl toward the center of the cylinder. By supplying the recirculated exhaust gas into the cylinder along with the intake air flow, the air-fuel mixture can be brought close to the spark plug located approximately in the center of the cylinder.
In addition to improving the ignition performance of the engine, the passage area of the primary intake passage can be kept small to ensure the strength of the intake swirl at extremely low loads.
Flammability can be increased. In addition, since the recirculated exhaust gas mixes with the intake air that flows at a high speed through the notch of the throttle valve, it is possible to recirculate the exhaust gas through the secondary intake passage and to recirculate the exhaust gas from when the engine is under low load. It is possible to prevent the timing of exhaust gas recirculation from being delayed and to accurately control the timing of exhaust gas recirculation.

[Brief explanation of the drawing]

The drawings show embodiments of the present invention. Figure 1 is a cross-sectional view of the first embodiment, Figure 2 is a longitudinal sectional view of the second embodiment, and Figure 3 is a diagram of the cylinder head of the same engine. It is a bottom view. 2...Cylinder, 5,5'...Intake passage, 8...
... Spark plug, 9 ... Primary side intake passage, 10 ... Secondary side intake passage, 11 ... Throttle valve, 12 ... Exhaust recirculation passage, 12a ... Exhaust outlet, 13 ... Exhaust recirculation valve, 14 ... Rotary valve, 15 ... Exhaust supply means, 16 ... Notch.

Claims (1)

[Scope of utility model registration request] The intake passage near the intake valve is equipped with a throttle valve.
The exhaust gas supply means is divided into a next side intake passage and a first side intake passage for generating a swirl of intake air in the cylinder, and includes an exhaust gas supply means for supplying a part of the exhaust gas into the cylinder through the intake passage. In the engine, a notch portion for leaking intake air is formed in a side portion of the throttle valve corresponding to a tangential direction of the intake swirl caused by the primary side intake passage, and a notch portion for leaking intake air is formed in the secondary side intake passage downstream of the notch portion. An exhaust gas recirculation control device for an engine, characterized in that an exhaust outlet of an exhaust supply means is opened.