JPH06248960A - Air intake device for engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption through all operational regions by selectively generating an oblique swirl and causing the occurrence of a tumble according to an operation condition, in the air intake system of a double intake air valve type engine. CONSTITUTION:In a double intake air valve type engine, respective subports 20 are formed right before the intake air valves 15 of the internally bent parts of two intake air ports 12 such that assist air is injected opposite to intake air flowing through the port. The subport 20 is communicated with the upper stream side of a throttle valve 10. A control valve is arranged to one intake air port 12. During low speed low load operation, the control valve is closed and intake air brought into a drift state by assist air is caused to flow only through one side of a cylinder 3 to generate an oblique swirl. During middle speed middle load ore more operation, the control valve is opened and intake air brought into a drift state is caused to flow through both sides of the cylinder 3 to cause the occurrence of a tumble.

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 producing a swirling flow in a cylinder during intake in a dual intake valve type engine for a vehicle, and more specifically, to a tumble (vertical swirl) and an oblique swirl depending on operating conditions. Concerning the method of generating.

[0002]

2. Description of the Related Art It is effective to promote combustion in order to improve fuel efficiency and output during engine operation. As a method of promoting this combustion, when various swirling flows are generated in the cylinder during the intake stroke, this swirling flow promotes the mixing of fuel and air, or produces turbulent flow during combustion, which is highly effective. If a tumble (vertical swirl) that swirls in the axial direction in the cylinder is generated as the swirling flow, the turbulence is greatly disturbed when the tumble collapses in the latter half of the compression stroke, generating a strong turbulent flow in the combustion chamber and increasing the combustion speed And fuel efficiency is improved.
However, in the low load region where the amount of fuel is small in engine operation, the mixed state of fuel and air also affects, so tumble is not necessarily optimum for fuel consumption.

Here, when the engine is operated with a mixture of stoichiometric air-fuel ratio, if a diagonal swirl having horizontal and vertical velocity components is generated in a low-speed low-load region where the amount of fuel and air is small, the mixture of fuel and air is generated. And turbulence both improved,
Best fuel economy. Further, in a region of medium speed, medium load or more where much fuel and air are present, strong turbulent flow is generated due to tumble, resulting in the best fuel economy. Therefore, it is desired to selectively generate the diagonal swirl and the tumble depending on the operating conditions.

Conventionally, as an intake device for an engine that generates tumble, assist air of a sub-port is injected to intake air passing through an intake port formed by bending at a substantially right angle, and the intake air is bent toward the outside of the port. Drift. And let the intake air flow into the cylinder via the exhaust valve side,
It has been proposed to generate a tumble that swivels axially in the cylinder.

[0005]

By the way, in the above-mentioned prior art, since the engine is operated by constantly generating tumble by the assist air from the sub-port, the engine is operated in a low speed and low load range including idle. However, there is a problem that the optimum fuel consumption cannot be obtained.

The present invention has been made in view of this point, and in an intake system of a dual intake valve type engine, oblique swirls and tumbles are selectively generated depending on operating conditions, so that fuel consumption etc. is improved in all operating regions. The purpose is to improve.

[0007]

In order to achieve the above object, the present invention is directed to an engine having a plurality of intake valves. The sub-port is provided so as to eject the assist air in opposition to the air, the sub-ports are connected to the upstream side of the throttle valve, and one of the intake ports is provided with a control valve that opens and closes according to operating conditions.

[0008]

According to the above construction, when the control valve is closed under low-speed low-load conditions during engine operation, the intake air that has been deflected by the assist air in the sub-ports flows in from one side in the cylinder and the horizontal and vertical speeds are increased. A diagonal swirl with components is generated. Further, under the condition of medium speed, medium load or more, the control valve opens, so that intake is performed from a plurality of intake ports. The intake air, which is biased by the assist air of the sub-ports in the plurality of intake ports, flows in from both sides in the cylinder, so that tumble that swivels only in the axial direction is generated. In this way, diagonal swirl and tumble are generated depending on operating conditions,
In both cases, combustion is promoted, resulting in good fuel economy and the like.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. A two intake valve type engine will be described with reference to FIGS. 1 and 2. Reference numeral 1 denotes an engine body, a piston 4 is reciprocally inserted into a cylinder 3 of a cylinder block 2, a combustion chamber 6 is provided on the top of the cylinder 3 in a cylinder head 5, and an ignition is performed substantially at the center of the combustion chamber 6. A plug (not shown) is arranged.

In the intake system, an intake manifold 11 downstream of the throttle valve 10 is connected to the cylinder head 5, and two intake ports 1 communicating with the intake manifold 11 are connected.
2, 13 are bifurcated by a branch wall 14 to form a combustion chamber 6
Is connected to one side of. Intake valves 15 and 16 are installed in the intake ports 12 and 13 so as to be in contact with and separated from a valve seat 17 to open and close. An injector 18 is attached to the end of the intake manifold 11 so that fuel is always injected into both intake ports 12 and 13.

Here, since the intake ports 12 and 13 are formed by bending at a right angle in a side view, it is possible to generate tumble by diverting the intake air to the outer curved side having a large radius of curvature by the assist air. become. Further, since the two intake ports 12 and 13 are arranged on the left and right sides of the cylinder 3, if intake air flows in from only one side in the cylinder axial direction, the air naturally swirls in the cylinder 3 also in the circumferential direction. , Generate diagonal swirls with horizontal and vertical velocity components.

Therefore, the intake port 1 of the cylinder head 5
2, the sub port 20 is provided so as to communicate with the upstream side of the intake valve 15 of the inner bent portion 12a having a small radius of curvature.
The sub port 20 is bent in an L-shape and is formed so as to face the intake air passing through the port. The sub port 20 is connected to the throttle valve 1 via the passage 21.
It is possible to communicate with the upstream side of 0 and always eject the assist air. Also at the intake port 13,
Similarly, a sub port 22 is provided, and this sub port 22
Is also connected to the upstream side of the throttle valve by the passage 23.

On the other hand, for example, a control valve 24 is provided in the intake port 12 on the left side so as to be opened and closed by an actuator 25 so as to be of a variable intake system. The control unit 27 inputs the engine rotation speed of the engine rotation speed sensor 28 and the throttle opening degree of the throttle opening degree sensor 29, and judges the operating condition based on both of them to determine the actuator 25.
The open / close signal is output to. Then, as shown in FIG. 3, the control valve 24 is closed in the low speed and low load region, and is opened in the medium speed, medium load and higher regions.

Next, the operation of this embodiment will be described. First, in the intake stroke during engine operation, the intake valves 15 and 16 simultaneously open at a predetermined timing, the piston 4 inside the cylinder 3 reciprocates and is sucked, and fuel is further injected from the injector. Therefore, under the operating conditions of idling, low speed or low load, the control unit 27 outputs a close signal to the actuator 25 to close the control valve 24. Therefore, the left intake port 12 is blocked, and the air A is sucked into the cylinder 3 only from the right intake port 13.

At this time, in the intake port 13 on the right side, due to the pressure difference between the upstream side of the throttle valve and the intake port, the sub port 2
Assist air B is ejected from 2 at a high speed, and the assist air B causes the intake air A flowing in the port to be eccentrically deflected outward. Then, the intake air A that has been unevenly flowed flows in a substantially linear manner in the axial direction in the cylinder 3 via the exhaust valve side. At this time, the swirl flow naturally swirls in the circumferential direction as well, because the swirl flow is naturally swirled in the cylinder only, and thus the oblique swirl C having horizontal and vertical velocity components is generated as shown in FIG. .

Therefore, under low-speed and low-load operating conditions with little fuel and air, the fuel and air are mixed well by the lateral component of the oblique swirl C. Further, in the compression stroke, the air-fuel mixture in the cylinder 3 is compressed by the movement of the piston 4, but due to the oblique swirl C, it disappears less in the latter half of the compression stroke, and a strong turbulent flow is generated in the combustion chamber 6. When the spark plug 7 in the combustion chamber 6 ignites the air-fuel mixture, the air-fuel mixture burns at a high combustion speed due to strong turbulence, and the combustion is promoted.

Under an operating condition of medium speed or medium load or more, the control unit 27 outputs an open signal to the actuator 25 to open the control valve 24. Therefore two intake ports 1
A large amount of air A is sucked in by 2 and 13, and the original intake state is obtained. In each of the two intake ports 12 and 13, the assist air B is jetted from the sub-ports 20 and 22, the intake air A is diverted, and the intake air A flows in from both left and right sides in the cylinder and swirls in the axial direction. . For this reason, the turns in the circumferential direction are mutually suppressed, and a strong tumble D that turns only in the axial direction is generated as shown in FIG.

Therefore, in the compression stroke, the air-fuel mixture in the cylinder 3 is compressed by the movement of the piston 4 and the tumble D collapses. However, when the tumble collapses in the latter half of the compression stroke, the flow of the air-fuel mixture is disturbed and the combustion chamber changes A strong turbulent flow is generated in 6. Therefore, in this case as well, during combustion, the air-fuel mixture burns at a high burning velocity due to turbulent flow, and the burning is promoted.

Although the embodiment of the present invention has been described above, the present invention is not limited to this.

[0020]

As described above, according to the present invention, in the intake system of the double intake valve type engine, oblique swirl is generated at low speed and low load, and tumble is generated at medium speed and medium load or higher. As a result, the vehicle is always driven with the best turbulence under all driving conditions, and the fuel efficiency is improved. The structure is based on the premise that the tumble is generated by the assist air of the sub port, so that the diagonal swirl and the tumble can be appropriately generated. Control is easy because the swirl or tumble is switched by opening and closing the control valve.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an embodiment of an intake device for an engine according to the present invention.

FIG. 2 is a transverse sectional view of the same.

FIG. 3 is a diagram showing opening / closing characteristics of a control valve.

FIG. 4 is a diagram showing a state in which an oblique swirl and tumble are generated.

[Explanation of symbols]

 10 Throttle valve 12,13 Intake port 12a Inner bending part 15,16 Intake valve 20,22 Subport 24 Control valve

Claims (2)

[Claims] 1. In an engine having a plurality of intake valves, a subport is provided immediately before an intake valve in an inwardly bent portion of each of the plurality of intake ports so as to eject assist air in opposition to intake air flowing through the ports. An intake system for an engine, characterized in that these sub-ports are connected to the upstream side of a throttle valve, and one intake port is provided with a control valve that opens and closes according to operating conditions. 2. The intake system for an engine according to claim 1, wherein the control valve operates so as to close when idle, low speed or low load, and open when medium speed or middle load or more.