JPH06193454A - Air intake device for engine - Google Patents

Abstract

PURPOSE:To generate proper tumble in each operation condition by controlling a flow rate of assist air in an intake air system which generates tumble while deviating the flow of intake air by the use of the assist air. CONSTITUTION:A tumble port 20 is formed on the inward bent portion 12a of an intake air port 12 so as to inject assist air against intake air passing through the port. The tumble port 20 is communicated with an upstream side from a throttle valve 10 through a passage 21 having a solenoid valve 22. A control unit 30 judges an operation condition. A flow rate of the assist air is decreased at a low load, while it is increased at a medium load. At a high load, the flow rate is set to substantially zero. The duty signals are output to the solenoid valve 22 for controlling the flow rate of the assist 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. The present invention relates to a device that changes the tumble generation state according to the above.

[0002]

2. Description of the Related Art In the engine operating range, particularly when the load is low, the intake air amount is greatly reduced to deteriorate combustion, and in order to improve this point, generally fuel is supplied abundantly. Fuel efficiency, emissions, and driving performance tend to deteriorate. Therefore, as a means for improving the fuel consumption at the time of such a low load, it is effective to generate various swirling flows in the cylinder during the intake stroke, thereby promoting combustion with strong turbulence during ignition and combustion. .

In the case of a swirl that swirls in the circumferential direction in the cylinder as the swirl flow, it is effective to make the air-fuel mixture uniform, but the use of turbulent flow in the combustion chamber is low. On the other hand, in the tumble (vertical swirl) that swirls in the axial direction in the cylinder, it is expected that when the tumble collapses in the latter half of the compression stroke, it will be greatly disturbed and a strong turbulent flow will be generated in the combustion chamber. Therefore, it is desired to improve the intake system of the engine to effectively generate tumble in the cylinder during intake at low load.

Conventionally, as an intake device for an engine that generates tumble, assist air of a tumble 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 outside the port. Drift to.
It has been proposed that the intake air flow into the cylinder via the exhaust port side to thereby generate a tumble that swirls in the cylinder in the axial direction.

[0005]

By the way, in the above-mentioned prior art, the flow rate of assist air from the tumble port is controlled only by the suction negative pressure. For this reason, at the time of low load such as idling, a large amount of assist air is jetted and the total intake air amount becomes too large, resulting in an increase in idling speed. In addition, there is a problem that a strong tumble cannot be generated at a medium load, and the intake is restricted at a high load to reduce the output.

The present invention has been made in view of this point, and in an intake system in which intake air is diverted by the assist air to generate a tumble, the flow rate of the assist air is controlled to obtain an appropriate tumble in each operating state. It is intended to occur.

[0007]

In order to achieve the above object, the present invention provides a tumble port at an inwardly curved portion of an intake port so as to eject assist air in opposition to intake air passing through the port, This tumble port is connected to the upstream side of the throttle valve via a passage having a solenoid valve, and the duty signal from the control unit is output to the solenoid valve to control the flow rate of assist air according to the engine operating state. is there.

[0008]

According to the above construction, in the intake stroke, negative suction pressure is applied to the tumble port, and assist air is jetted out to the intake port at high speed, and this assist air causes the intake air passing through the intake port to drift outward, Therefore, the intake air flows in the axial direction of the cylinder via the exhaust port side, and tumble is generated in the cylinder. On the other hand, the control unit determines the engine operating state, and the solenoid valve controls the flow rate of assist air at a low load to be small, at a medium load to be large, and at a high load to be substantially zero. Therefore, at low and medium loads, the flow rate of assist air corresponds to the intake air amount, and appropriate tumble is generated to promote combustion. Also, at high load, the original performance of the intake port will be maximized, and the output will increase.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. A single 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 at the top of the cylinder 3 in a cylinder head 5, and a spark plug is provided substantially at the center of the combustion chamber. 7
Are placed.

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 the intake manifold 11 is connected to one side of the combustion chamber 6. An intake valve 13 is installed in the intake port 12 so as to come into contact with and separate from the valve seat 14 to open and close. An injector 15 is attached to an end of the intake manifold 11 so as to inject fuel into the intake port 12.

Since the intake port 12 is bent at a substantially right angle in a side view, the intake air is diverted by the assist air to the outer curved side having a large radius of curvature.
It is possible to generate tumble. Therefore, in the intake port 12 of the cylinder head 5, the tumble port 2 is provided on the upstream side of the intake valve 13 of the inner bent portion 12a having a small radius of curvature.
0s are provided so as to communicate with each other. This tumble port 20 is L
It is bent in a V shape and is formed so as to be oriented in a direction facing the intake air passing through the intake port 12. The tumble port 20 communicates with the upstream side of the throttle valve 10 via a passage 21 so that the assist air can always be ejected.

Furthermore, in order to change the tumble generation state,
A solenoid valve 22 is provided in the passage 21. Further, it has a control unit 30 to which signals from a temperature sensor 25 such as cooling water, an engine speed sensor 26, and a load sensor 27 are input,
The duty signal from the control unit 30 is output to the solenoid valve 22 to control the flow rate Q of the assist air B.

The control unit 30 will be described with reference to FIG. It has an operating state determination unit 31 to which the signals of the various sensors 25 to 27 are input, and determines the operating state based on the factors of engine speed and load in the engine warm-up state. This operating state determination signal is input to the assist air flow rate setting unit 32, and the assist air flow rate Q is set for each operating state by referring to the map. That is, as shown in FIG. 4, the flow rate Q is set low at low and medium speeds and set high at high speeds.
Further, the flow rate Q is low at low load, high at medium load, and set to substantially zero at high load. This flow rate signal is input to the duty ratio converter 33 to be converted into the duty ratio D, and this duty signal is output to the solenoid valve 22.

Next, the operation of this embodiment will be described. First, in the intake stroke during engine operation, the intake valve 13 opens and closes at a predetermined timing, and the air is taken into the cylinder 3.
The piston 4 inside the cylinder 3 reciprocates, and further a predetermined fuel is injected from the injector 15. In addition, suction negative pressure is applied to the tumble port 20 and the throttle valve 10
The air is sucked from the upstream side of the above through the passage 21, and the assist air B is jetted into the intake port 12 at a high speed.

Therefore, the intake air A passing through the intake port 12
Is biased to the outer curved side in the port by the assist air B from the tumble port 20, and as a result, the flow velocity distribution around the valve is directed to the exhaust port side as shown in FIG. Therefore, the intake air A from the intake port 12 flows into the cylinder 3 substantially linearly via the exhaust port side, whereby the inside of the cylinder 3 and the combustion chamber 6 is
As shown in FIG. 1, a tumble C that swivels in the cylinder axis direction is effectively generated.

Further, in the compression stroke, the mixture in the cylinder 3 is compressed by the movement of the piston 4, and the tumble C also collapses. Then, when the tumble collapses in the latter half of the compression stroke, the flow of the air-fuel mixture is disturbed and a turbulent flow is generated in the combustion chamber 6. When the spark plug 7 in the center of the combustion chamber 6 is ignited there, the air-fuel mixture burns at a high burning speed due to turbulent flow, thus promoting the burning.

At this time, in the control unit 30, as shown in the flowchart of FIG. 5, the operating state is judged by the engine speed, the load, etc., and the assist air flow rate Q is set according to the operating state. Therefore, when the throttle opening is small and the load is low, the solenoid valve 22 controls the flow rate Q of the assist air B to be small by the duty signal. Therefore, under the condition that the intake air amount is small according to the throttle opening, the intake air amount due to the assist air B is prevented from being excessive, and the idle speed and the like are prevented from increasing. Further, since the flow rate Q of the assist air B corresponds to the intake air amount, an appropriate tumble C is generated and combustion is promoted.

At a medium load with an increased throttle opening,
A large amount Q of the assist air B is controlled by the solenoid valve 22. For this reason, a large amount of intake air A corresponding to the throttle opening degree is effectively biased by the assist air B and flows in the axial direction in the cylinder, thus generating a strong tumble. Therefore, a strong turbulent flow is generated during combustion, combustion is effectively promoted, and the output etc. in this operating region is increased. When the engine speed further increases at such low and medium loads, the flow rate Q of the assist air B is increased.
Is increased as a whole, so that the tumble C is appropriately generated at high speed.

Furthermore, when the throttle opening is large and the load is high, the flow rate Q of the assist air B is controlled by the solenoid valve 22 as the load increases, and becomes substantially zero during WOT. Therefore, a large amount of intake air A flows through the entire intake port 12 without being restricted, and the original performance of the intake port is maximized. As a result, the intake charging efficiency is improved and the output is increased. .

Although the embodiment of the present invention has been described above, it is needless to say that the invention can be similarly applied to other than the single intake valve type engine.

[0021]

As described above, according to the present invention,
Since the tumble port is provided in the intake system of the engine and the flow rate of the assist air in the tumble port is controlled according to the engine operating state, it is possible to generate an appropriate tumble in each operating state. In particular, when the load is low, the flow rate of assist air is small, so that it is possible to prevent the engine speed from increasing. Since a large amount of assist air is controlled at medium load, strong tumble is generated, combustion is effectively improved, and exhaust gas and fuel consumption can be improved. At high load, the assist air flow rate is controlled to be substantially zero, so that the output can be increased by the original performance of the intake port.

[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 block diagram showing a configuration of a control unit.

FIG. 4 is a diagram showing a flow rate of assist air set according to each operating state.

FIG. 5 is a flowchart showing a state of flow control of assist air.

[Explanation of Codes] 3 Cylinder 10 Throttle Valve 12 Intake Port 12a Inner Bend 13 Intake Valve 20 Tumble Port 21 Passage 22 Solenoid Valve 30 Control Unit

Claims (2)

[Claims] 1. A tumble port is provided in an inwardly curved portion of an intake port so as to eject assist air in opposition to intake air passing through the port, and the tumble port is provided with a throttle valve through a passage having a solenoid valve. An intake device for an engine, which communicates with an upstream side and outputs a duty signal from a control unit to a solenoid valve to control a flow rate of assist air according to an engine operating state. 2. The control unit reduces the flow rate of assist air at low load, increases it at medium load, and sets it to substantially zero at high load, and further sets it when the engine speed is high. The intake system for an engine according to claim 1, wherein: