JPH06248956A - Intake system for engine - Google Patents

Abstract

PURPOSE:To cause strong tumbling in all region from low and middle loads to a high load in an intake system causing tumbling by drifting intake air by means of assist air. CONSTITUTION:A sub-port 20 is provided, so that assist air can be injected against intake air passing through the port, directly before the inlet valve 13 of the inner curved part 12a of an air intake port 12; the sub-port 20 is communicated with upstream of a throttle valve 10; and a partitioning wall 22 is installed, so as to be divided in two of an outer curved side primary port 23 and an inner curved side secondary port 24, on the air intake port 12, etc., upstream of the sub-port 20. Also a control valve 25 is provided on the secondary port 24, and is operated so as to be closed in low and middle speed regions to variably intake air to cause strong tumbling in all the region of a load region and is opened in a high-speed region to efficiently intake air.

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 generating tumble (vertical swirl) in a cylinder by using assist air during intake in a four-cycle gasoline engine for a vehicle. Regarding tumble strengthening measures in the area.

[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. Here, when a lateral swirl that swirls in the circumferential direction in the cylinder is generated as the swirling flow, it is effective in homogenizing the air-fuel mixture, but the effect of turbulent flow in the combustion chamber is low. On the other hand, when a tumble (vertical swirl) that swirls in the axial direction in the cylinder is generated, it is expected to be greatly disturbed when the tumble collapses in the latter half of the compression stroke to generate a strong turbulent flow in the combustion chamber. Therefore, it is desired to generate tumble effectively in all load regions of engine operation.

Conventionally, as an intake device for an engine which generates tumble, assist air of a subport is injected to intake air passing through an intake port formed by bending at a substantially right angle, and the intake air is bent to 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.

[0004]

By the way, in the above prior art, the assist air from the subport is
The flow rate is controlled by the differential pressure between the throttle upstream and the intake port. Therefore, when the load is low such as at idle, the flow rate of assist air is very large due to the large differential pressure. Therefore, if the port is throttled so that the flow rate of the assist air does not exceed the idle flow rate, a strong tumble cannot be generated in the region after the medium load. Further, when the load is high, there is a problem that the flow rate of assist air decreases due to the small differential pressure, and the tumble becomes very weak.

The present invention has been made in view of this point, and in an intake system in which intake air is diverted by assist air to generate tumble, strong tumble is generated in all regions from low to medium loads. The purpose is to do.

[0006]

In order to achieve the above object, according to the present invention, a sub-port injects assist air in opposition to intake air passing through the inside of the intake port immediately before the intake valve at the inwardly curved portion. In an intake system for an engine in which the sub-port is communicated with the upstream side of the throttle valve, a partition wall is divided into a primary port on the outer bend side and a secondary port on the inner bend side in the intake passage upstream of the sub-port. The secondary port is provided with a control valve that opens and closes according to the operating state.

[0007]

According to the above construction, when the control valve is closed, for example, in the low / medium speed range during engine operation, intake is performed only from the primary port. Therefore, under these conditions, when the load is low and medium, assist air is jetted from the subport at high speed,
The intake air flowing through the primary port is further biased to the outward bend side, and this intake air flows in the axial direction of the cylinder to generate a strong tumble. Also, when the load is high, the amount of assist air decreases, but a large amount of intake air flows at high speed through the primary port, so that similarly strong tumble is generated by the intake air itself. In this way, strong tumble is obtained in all load regions, combustion is promoted, and fuel consumption and output are improved.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, the overall configuration will be described. 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. Plugs etc. are arranged.

In the intake system, an intake manifold 11 downstream of the throttle valve 10 is connected to the cylinder head 5, and an intake port 12 communicating with this intake manifold 11 is connected to one side of the combustion chamber 6. Intake valve 1 in intake port 12
3 is installed so as to be brought into contact with and separated from the valve seat 14 and opened and closed, and an injector 15 is attached to an end portion of the intake manifold 11 so as to inject fuel into the intake port 12.

Here, since the intake port 12 is formed so as to be bent at a substantially right angle to the cylinder axis, a tumble may be generated by causing the intake air to be deflected to the outer curved side having a large radius of curvature by the assist air. It will be possible. Therefore, in the intake port 12 of the cylinder head 5, the sub-port 20 is provided in communication with the upstream side of the intake valve 13 of the inner curved portion 12a having a small radius of curvature. This subport 2
0 is bent in an L shape and is formed in a direction facing the intake air passing through the port. And subport 20
Is communicated with the upstream side of the throttle valve 10 via the passage 21, and the assist air can be ejected by the pressure difference between the intake port and the throttle valve upstream.

As a measure for strengthening the tumble, a partition wall 22 is installed inside the intake port 12 upstream of the sub-port 20 and the intake manifold 11 so as to be divided into upper and lower parts.
A primary port 23 is formed on the outside of the partition wall 22 so as to generate a flow of intake air that is biased to the outer curved side having a large radius of curvature. Further, a secondary port 24 is formed inside the partition wall 22, and a control valve 25 is provided on the secondary port 24 so as to be opened and closed by an actuator 26, which is a variable intake system. Control unit 27
Is input with the engine speed of the engine speed sensor 28, determines a low-medium speed range and a high-speed range, and outputs an opening / closing signal to the actuator 26. Then, as shown in FIG. 2, the control valve 25 is controlled to be closed in the low / medium speed range and to be opened in the high speed range.

Next, the operation of this embodiment will be described. First, in the intake stroke during engine operation, the intake valve 13 opens at a predetermined timing, the piston 4 inside the cylinder 3 reciprocates and is sucked into the cylinder 3, and further a predetermined fuel is injected from the injector 15. . At this time, air is sucked from the upstream side of the throttle valve 10 due to the differential pressure between the intake port 12 and the upstream side of the throttle valve 10, and this assist air B is ejected from the sub port 20 in opposition to the intake air A flowing through the intake port 12.

Therefore, in the low and medium speed range, the control unit 27 outputs a close signal to the actuator 26 to close the control valve 25. Therefore, the intake air A flows only through the primary port 23 on the outward bend side and is variably sucked. In this operating state, at the time of low and medium load including idle where the throttle opening is relatively small, the sub-port 20
A large amount of assist air B is jetted from the high speed. Therefore, the intake air A flowing through the primary port 23 is further strongly biased to the outward bend side by the assist air B, and the biased intake air A flows into the cylinder 3 substantially linearly via the exhaust port side. As a result, a strong tumble C that swirls in the cylinder axis direction is generated inside the cylinder 3 and the combustion chamber 6 as shown in FIG.

When the throttle opening is large and the load is high, the pressure difference between the intake port 12 and the upstream side of the throttle valve 10 is small, so the assist air B from the sub port 20 is small, but a large amount of intake air A is generated in the primary port 23. As a result, the current flows in a state in which it is biased toward the outer curved side. Therefore, a strong tumble C is generated in the cylinder 3 by the intake air A itself in the primary port 23 as in the above. in this case,
Since the flow velocity of the air flowing through the primary port 23 becomes faster, the volumetric efficiency also increases.

In the compression stroke, the mixture in the cylinder 3 is compressed by the movement of the piston 4, so that the tumble C also collapses. However, when the tumble collapses in the latter half of the compression stroke, the flow of the mixture is disturbed and combustion occurs. Turbulence is generated in the chamber 6. When ignited by the spark plug of the combustion chamber 6, the air-fuel mixture burns at a high combustion speed due to turbulent flow. In this way, in the low and medium speed operation state, combustion is promoted in all load regions.

In the high-speed operation state, the control unit 27
Outputs an open signal to the actuator 26, which causes the control valve 25 to open. Therefore, a large amount of air is efficiently taken in from both the primary port 23 and the secondary port 24.

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

[0018]

As described above, according to the present invention, the intake system of the engine is provided with the sub-port and the variable intake system divided into the outer bend side and the inner bend side in combination.
In the low / medium speed range, the intake is performed only from the outer bend side, so that under this operating condition, a strong tumble can be generated in the entire range from the low / medium load to the high load. Therefore, fuel efficiency and output are improved. In particular, when the load is high, the flow velocity of air is increased and the volumetric efficiency is improved. Therefore, it is possible to shift the gear ratio to a higher speed, and fuel consumption is further improved. In the high speed range, intake is performed from the entire intake passage, so intake efficiency is not impaired.

[Brief description of drawings]

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

FIG. 2 is a diagram showing an opening / closing characteristic of a control valve.

[Explanation of symbols]

 10 Throttle Valve 12 Intake Port 12a Inner Bent Section 13 Intake Valve 20 Sub Port 22 Partition Wall 23 Primary Port 24 Secondary Port 25 Control Valve

Claims (2)

[Claims] 1. A subport is provided immediately before an intake valve at an inwardly bent portion of an intake port so as to eject assist air in opposition to intake air passing through the port, and the subport is connected to an upstream side of a throttle valve. In the intake system of an engine, a partition wall is installed in the intake passage upstream of the subport so as to be divided into a primary port on the outer bend side and a secondary port on the inner bend side, and the secondary port opens and closes according to operating conditions. An intake device for an engine, characterized in that a control valve for controlling the intake air is provided. 2. An intake system for an engine, wherein the control valve operates so as to close in a low and medium speed range and open in a high speed range.