JP2508636Y2 - Intake port structure of internal combustion engine - Google Patents

Description

The present invention relates to an internal combustion engine including a swirl port for generating intake swirl in a combustion chamber and a fuel injection valve for injecting fuel toward the swirl port. .

[Conventional technology]

There is known an engine in which a swirl port and a straight port are provided in the intake valve of each cylinder and an intake control valve opens and closes the straight port side intake passage according to an engine load.

The intake control valve is provided for the purpose of operating the internal combustion engine by switching between a lean air-fuel ratio and a rich air-fuel ratio in accordance with a load state. The lean air-fuel ratio operation is performed by switching the fuel injection amount and the ignition timing while closing the passage.

The intake control valve is closed to allow the total intake amount to flow into the cylinder from the swirl port and generate a strong swirl of the air-fuel mixture in the combustion chamber, thereby achieving stable combustion even at a lean air-fuel ratio and reducing fuel consumption. be able to. on the other hand,
When the engine is under high load and high rotation, the intake control valve is opened to increase the intake amount to the cylinder, and the fuel injection amount and the ignition timing are set to the rich air-fuel ratio (or the theoretical air-fuel ratio) according to the opening operation of the intake control valve. ) Side, it is possible to secure high output of the engine.

In an engine equipped with an intake control valve, various considerations have been made regarding the arrangement of fuel injection valves and the method of fuel injection.In order to expand the lean side of the air-fuel ratio of the air-fuel mixture and improve the response during transition, swirl is generally used. It has been found effective to inject fuel into both the port and the straight port.

As an engine of this type, the applicant of the present invention has conducted a real-life sho 61
-147336 has a proposal. In the engine described in the publication, a fuel injection valve having two injection ports that respectively open toward both ports is arranged in a partition wall that divides the intake passage into a straight port side and a swirl port side, and a single fuel injection is performed. By injecting fuel into both ports with a valve, the same effect as that of providing a fuel injection valve for each port individually is obtained.

[Problems to be solved by the device]

In the internal combustion engine disclosed in Japanese Utility Model Laid-Open No. 61-147336, a helical type is used as the swirl port. In the helical type swirl port, the port shape near the inlet of the combustion chamber is spiral, and the entire intake flow passes through the spiral passage so that the swirl velocity component is changed before it flows from the intake valve into the combustion chamber. To be given.

However, when the fuel is injected toward the swirl port as in the internal combustion engine of the above publication, a part of the injected fuel travels straight and collides with the spiral passage wall surface of the swirl port and adheres thereto. Become. The fuel adhering to the wall surface flows along the wall surface, and when the intake valve opens, relatively large droplets are sucked into the combustion chamber as large droplets. The problem is that the amount of NO _x generated increases. In addition, since a part of the injected fuel is supplied to the combustion chamber as relatively large droplets, there is a problem that torque fluctuation during combustion is increased and performance is degraded during transient response.

Since there is no straight line in the intake passage at the inlet of the helical port, it is not possible to eliminate the adherence of fuel to the wall surface even if the fuel injection direction is changed, and the problem of fuel adherence when injecting fuel into the swirl port is It was one of the problems to be solved.

In view of the above problems, the present invention provides an intake port structure of an internal combustion engine that can generate a uniform air-fuel mixture in a combustion chamber with little fuel wall adhesion when fuel is injected toward a swirl port. It is an object.

[Means for solving the problem]

According to the present invention, a swirl port, a straight port, an intake control valve that closes an intake passage continuing to the straight port when the engine load is low, and an intake passage that is downstream of the intake control valve and is open to the swirl port. In the internal combustion engine having a straight port and a fuel injection valve for injecting fuel, the swirl port is provided with a swirl generating projection on a straight port side of a wall surface facing the intake valve of the combustion chamber inlet, The projection has a substantially triangular pyramid shape having a first guide surface that deflects the intake air flow to give a swirl velocity component in a direction perpendicular to the cylinder axis, and a second guide surface that guides the intake air flow toward the intake valve. Fuel injection from the fuel injection valve to the swirl port is performed directly between the second guide surface and the port wall surface facing the second guide surface and directly toward the back surface of the intake valve umbrella portion. There is provided an intake port structure for an internal combustion engine, which is characterized by the above.

[Action]

Most of the intake air flow that has flowed into the swirl port from the intake passage is given a swirl velocity component by the first guide surface, flows in a spiral shape around the axis of the intake valve, and enters the combustion chamber from the intake valve in the horizontal direction. Forming a swirl. On the other hand, the other part of the intake flow goes straight along the second guide surface, flows from the intake valve toward the lower part of the combustion chamber, collides with the horizontal swirl, and merges with the swirl with respect to the horizontal plane. Incline. At this time, the fuel injected into the swirl port passes under the second guide surface, enters the intake valve opening, collides with the back surface of the intake valve head, and is scattered, and is further atomized by the collision of the two flows. Then, it gets on the diagonal swirl and diffuses into the combustion chamber. As the compression process progresses, the diagonal swirl shifts to a horizontal stable swirl, and a homogeneous air-fuel mixture is formed in the combustion chamber.

〔Example〕

The present invention will be described below with reference to the accompanying drawings. First
FIG. 1 is a schematic diagram showing an example of the configuration of an internal combustion engine that employs an intake port structure according to the present invention.

In the figure, 10 is a cylinder block, 12 is a combustion chamber, 14
Indicates a spark plug, 12a and 12b are intake ports, and a so-called four-valve structure in which two intake valves 16a and 16b and two exhaust valves 18a and 18b are provided in each intake port and exhaust port is shown. The first intake port 12a is a swirl port configured in a shape convenient for forming an intake swirl. The second intake port 12b is a straight type.

An intake control valve 32 as a butterfly valve is provided in the intake passage that continues to the straight intake port 12b.When the intake control valve 32 is closed, intake air is introduced only from the swirl port 12a, and the engine cylinder Since a powerful swirl (swirl flow) of intake air is generated inside, stable lean mixture combustion is possible. When the intake control valve 32 is opened, air is introduced from both the intake ports 12a and 12b, and the intake amount increases. A lever 34 is attached to the valve shaft of the intake control valve 32 of each cylinder.
Is attached to the negative pressure actuator 38 via a rod 36. Negative pressure actuator 38
Is composed of a diaphragm 40 and a spring 41. When the negative pressure is not applied to the diaphragm 40, the spring 41 acts to push the diaphragm 40 to the left in the figure, and the intake control valve 32 is in the open position. When a negative pressure is applied to the diaphragm 40, the diaphragm 40 is pulled rightward against the spring 41, and the intake control valve 32 moves to the intake port.
Take the position to close 12b.

The diaphragm 40 is connected to a negative pressure tank 45 via an electromagnetic three-way switching valve 44. The negative pressure tank 45 is connected via a check valve to a negative pressure outlet port 24 provided on the intake pipe 20 downstream of the throttle valve 22.

The check valve 46 holds a negative pressure applied to the diaphragm 40. The switching valve 44 has three ports 44a, 44b, and 44c. When electricity is removed, the ports 44a and 44b communicate with each other. The diaphragm 40 communicates with the negative pressure port 24. The diaphragm 40 is in communication with the atmosphere. The switching valve 44 is an electronic control unit (ECU) 5 of the engine.
The operation is controlled by 0.

Further, a fuel injection valve 26 is arranged on a partition wall 28 that partitions the swirl port 12a and the straight port 12b.

In this embodiment, the fuel injection valve 26 has two injection ports 26a and 26b in one body, and these injection ports 26a and 26b are provided.
Are provided so as to direct the intake valve 16a of the swirl port 12a and the intake valve 16b of the straight port 12b, respectively.

2 to 3 are diagrams showing details of the swirl port 12a. In this embodiment, the intake passage following the swirl port
20a is substantially straight, and the intake valve 16a of the swirl port 12a
A triangular pyramid-shaped swirl generating projection 2 is provided on the wall surface on the side of the upper straight port 12b. The protrusion 2 is a first guide surface 2a and a second guide surface which are in contact with each other via a ridge line 2d and a ridge line 2d extending from the apex 2c toward the fuel injection valve 26 side of the partition wall 28 and protruding from the apex 2c. With 2b. The first guide surface 2a has a shape that deflects the intake air flow toward the outer circumference of the cylinder and causes it to flow along the outer peripheral wall surface of the cylinder of the swirl port to give a swirl velocity component to the intake air flow.
(See FIG. 3A) The angle (indicated by α in FIG. 3A) between the ridgeline 2e connecting the first guide surface and the wall surface of the swirl port and the central axis of the intake passage 20a produces an appropriate swirling flow. Therefore, it is preferable to set it to 45 degrees or less.

In addition, the second guide surface 2b is provided with a part of the intake air flow downward with the intake valve.
Since it is deflected toward 16a, the angle θ (3rd
As shown in Fig. B), since the angle θ guides the injected fuel to the intake valve umbrella portion, the injection port 26 on the swirl port side of the fuel injection valve 26
The angle of the axis of a is equal to or greater than the angle θ ₀ with the horizontal plane, and preferably the height of the vertex C is such that the second guide surface is parallel to the axis of the injection port 26a as shown in FIG. 3B. Is set.

FIG. 4 is a schematic view of the swirl port viewed from the position of the fuel injection port 26a, FIG. 4A shows the swirl port of this embodiment, and FIG. 4B shows the conventional helical swirl port. There is. In the conventional helical port, the port wall (B5 in FIG. 4) becomes an obstacle and fuel does not reach the intake valve 16a directly from the fuel injection port, whereas in the swirl port of this embodiment (FIG. 4A) the lower half of the port is used. It can be seen that there is no obstacle in the fuel and fuel can reach the intake valve 16a directly from the injection port.

The effect obtained by setting the shape of the protrusion 2 as described above will be described below.

The intake flow flowing into the combustion chamber 12 through the intake pipe 20a is partly deflected by the first guide surface 2a when passing through the swirl generating projection 2, and the swirling flow around the axis of the intake valve 16a. And flows into the combustion chamber 12.

The other part of the intake air flow is the second guide surface 2b of the protrusion 2.
And linearly flow from the intake valve 16a toward the lower part of the combustion chamber. These two flows collide in the vicinity of the intake valve 16a and form a swirl S inclined with respect to the horizontal plane in the combustion chamber. (FIG. 5) On the other hand, the fuel injected from the injection port 26a of the fuel injection valve 26 rides on the air flow flowing along the second guide surface 2b of the protrusion 2 and is sucked without colliding with the second guide surface 2b. It reaches the valve 16a, collides with the umbrella portion of the intake valve 16a, atomizes, and scatters into the combustion chamber. This fuel is further atomized by the collision of the two air streams described above and rides on the inclined swirl to diffuse into the combustion chamber. As the compression stroke of the cylinder progresses, the tilted swirl containing atomized fuel shifts to a stable horizontal swirl due to the rise of the piston, but due to the turbulence during this shift, intake air and fuel are uniformly mixed, and the combustion chamber A homogeneous air-fuel mixture is formed. Therefore, the amount of NO _X generated during combustion is reduced. Further, since the fuel injected from the fuel injection valve reaches the intake valve 16a without colliding with the port wall surface, it is possible to prevent the fuel from adhering to the wall surface. Further, a small amount of fuel adheres to the second guide surface 2b of the protrusion 2, but the fuel adheres to the guide surface 2b by making the second guide surface 2b parallel to the fuel injection axis as in this embodiment. Can be minimized, and a small amount of the adhered fuel is quickly evaporated by the intake air flow, so that the adhered fuel does not flow into the combustion chamber as droplets. Therefore, the fuel adhering to the wall surface does not increase in NO _X and torque fluctuation due to flowing into the combustion chamber.

[Effect of device]

According to the present invention, by improving the structure of the swirl port as described above so that the injected fuel directly reaches the opening of the intake valve, the mixture concentration in the combustion chamber is made uniform and the fuel It is possible to prevent adhesion to the port wall surface. Therefore, the present invention reduces the amount of NO _X in the exhaust gas and reduces torque fluctuations during operation.

[Brief description of drawings]

FIG. 1 is a diagram showing the structure of an internal combustion engine adopting the intake port structure of the present invention, FIG. 2 is a perspective view showing an embodiment of the intake port structure of the present invention, and FIGS. 3A and 3B are of FIG. FIG. 4 is a view showing the details of the swirl port protrusion, FIGS. 4A and 4B are views showing the swirl port of the embodiment of FIG. 1 and a conventional helical swirl port as viewed from the position of the fuel injection port, and FIG. It is a figure which shows the swirl produced in a combustion chamber. 2 ... Protrusion, 2a ... First guide surface, 2b ... Second guide surface, 2c ... Apex, 12 ... Combustion chamber, 12a ... Swirl port, 12b ... Straight port, 16a, 16b ...... Intake valve, 20
a …… Swirl port side intake passage

Claims (1)

(57) [Scope of utility model registration request] 1. A swirl port, a straight port,
An intake control valve that closes the intake passage that follows the straight port when the engine load is low, and a fuel injection valve that opens in the intake passage downstream of the intake control valve and injects fuel into the swirl port and the straight port In the internal combustion engine, the swirl port is provided with a swirl generating projection on the straight port side of the wall surface facing the intake valve at the inlet of the combustion chamber, and the swirl generating projection deflects the intake flow with respect to the cylinder axis. It has a substantially triangular pyramid shape having a first guide surface that gives a vertical swirl velocity component and a second guide surface that guides the intake flow toward the intake valve, and the fuel from the fuel injection valve to the swirl port is formed. The injection is performed so as to be directed between the second guide surface and the port wall surface facing the second guide surface and directly toward the back surface of the intake valve head portion, and the intake port structure of the internal combustion engine is characterized. Structure.