JPH0653727U - Engine intake system - Google Patents

Abstract

(57) [Summary] [Purpose] A simple structure that uses assist air to effectively generate strong tumble and improve combustion. [Structure] Inner bent portions 12a, 1 of the intake ports 12, 13
The tumble port 20 immediately before the intake valves 15 and 16 of 3a,
The tumble port 20 is provided so as to be opposed to the intake air in the port, and the tumble port 20 is connected to the upstream side of the throttle valve 10 via a passage 21. Then, when the load is low, assist air is ejected from the tumble port 20 and the intake air passing through the port is biased to the outside curve side of the port to generate a tumble that swirls in the cylinder 3 in the axial direction. The tumble port 20 is machined using the mounting hole 25 of the valve seat 17 and is formed with high accuracy.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an intake device for generating a tumble (vertical swirl) in a cylinder during intake in a four-cycle gasoline engine for vehicles, and more particularly to a system using assist air.

[0002]

[Prior art]

 In the operating region of the engine, especially at low load, the intake air amount is greatly reduced, resulting in poor combustion, and in order to improve this point, fuel is generally supplied abundantly to improve fuel economy, emission, Driving performance tends to deteriorate. Therefore, as a means to improve fuel efficiency at low loads like this, it is effective to generate various swirling flows in the cylinder during the intake stroke, which promotes combustion with strong turbulence during ignition and combustion. Is.

In the case of a lateral swirl that swirls in the circumferential direction in the cylinder as the swirling flow, it is effective to make the air-fuel mixture uniform, but the use of turbulence in the combustion chamber is low. On the other hand, in a tumble (vertical swirl) that swirls in the axial direction in the cylinder, it is expected that the tumble will be greatly disturbed when the tumble collapses in the latter half of the compression stroke, resulting in strong turbulence 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 a low load.

Conventionally, there is a prior art of an engine intake device that generates tumble, for example, Japanese Utility Model Laid-Open No. 59-156122. Here, an auxiliary intake passage is provided for the intake port so that the jetted intake air flows in the direction of the diameter of the cylinder, and an on-off valve is provided on the inlet side of the intake port. It is shown that, when the load is low, the on-off valve closes the intake port, the sub-intake passage intakes air, and the jetted intake air is swirled in the axial direction of the cylinder to generate a vertical swirl (tumble flow).

[0005]

[Problems to be solved by the device]

 By the way, in the above-mentioned prior art, since the intake system of the auxiliary intake passage is separately provided and the on-off valve is added, the structure and control are complicated, and it is applicable to the multiple intake valve engine. There are problems such as difficulty.

The present invention has been made in view of this point, and an object thereof is to effectively generate a strong tumble and improve combustion with a simple configuration using assist air.

[0007]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a tumble port immediately before the intake valve at the inner bend of the intake port, ejects assist air to face the intake air passing through the port, and sucks the intake air outside the port. The tumble port communicates with the upstream side of the throttle valve via a passage, and the tumble port is formed into an L-shape by a hole machined from the mounting hole of the valve seat.

[0008]

[Action]

 Based on the above structure, the tumble port provided in the intake port is formed with high accuracy by the hole machined using the mounting hole of the valve seat. When the load is low, assist air is ejected from the tumble port at a high speed due to a large suction negative pressure, and this intake air causes the intake air passing through the intake port to be deflected outward. Therefore, the intake air flows in the axial direction of the cylinder via the exhaust port side, and a strong tumble is effectively generated in the cylinder.

[0009]

【Example】

 Embodiments of the present invention will be described below with reference to the drawings. A two-suction 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 the combustion chamber 6 is provided substantially at the center of the combustion chamber. An ignition plug 7 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 12 and 13 communicating with the intake manifold 11 are branched into two branches by a branch wall 14. And is communicated with one side of the combustion chamber 6. The intake valves 15 and 16 are installed in the intake ports 12 and 13 so as to open and close by contacting with and separating from the valve seat 17. 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.

Since the two bifurcated intake ports 12 and 13 are bent and formed substantially at right angles in a side view, by assisting the intake air to deflect the intake air to the outer curved side having a large radius of curvature, It is possible to generate tumble. Therefore, the tumble port 20 is provided in communication with the two intake ports 12 and 13 of the cylinder head 5 just before the intake valves 15 and 16 of the inwardly curved portions 12a and 13a having a small radius of curvature. The tumble port 20 is bent in an L shape so that the injection port 20a faces the intake air passing through the port. The tumble port 20 is connected to the upstream side of the throttle valve 10 by a passage 21 so that the assist air can be ejected particularly when the load is low.

On the other hand, the tumble port 20 is required to be formed with high accuracy because the effect of assist air is greatly influenced by the ejection direction, the diameter, and the like. Therefore, the tumble port 20 is formed by machining from the side of the combustion chamber 6 using the mounting hole 25 of the valve seat 17 before press-fitting. That is, a hole 26 having a predetermined diameter is formed from the bottom of the mounting hole 25 to the outside of the cylinder head 5, and another hole 27 is formed from the same position to a predetermined position on the port side. Then, the openings of both holes 26, 27 on the mounting hole side are closed by press-fitting and fixing the valve seat 17, so that the two holes 26, 27 are communicated with each other to form the tumble port 20 with high accuracy.

Next, the operation of this embodiment will be described. First, in the intake stroke during engine operation, the intake valves 14 and 15 are simultaneously opened and closed at a predetermined timing to be sucked into the cylinder 3, the piston 4 inside the cylinder 3 reciprocates, and the injector 18 further releases a predetermined fuel. Is jetted. Therefore, at the time of low load such as idling, the opening of the throttle valve 10 is small and the intake air is throttled, but a large intake negative pressure is applied to the tumble port 20. Therefore, the air is sucked from the upstream side of the throttle valve 10 by the passage 21 and the tumble port 20, and this assist air B is jetted from the jet port 20a of the tumble port 20 into the intake ports 12 and 13 at high speed.

Therefore, the intake air A passing through the intake ports 12 and 13 is diverted to the outward bend 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 as shown in FIG. It will be oriented toward the exhaust port side. Therefore, the intake air A from the intake ports 12 and 13 flows into the cylinder 3 substantially linearly via the exhaust port side regardless of the shape of the ports, and as a result, inside the cylinder 3 and the combustion chamber 6. At, the tumble C that swivels in the cylinder axis direction is effectively generated as shown in FIG. Then, the tumble C flows well in a region including the widest portion in the cylinder 3 and the vicinity of the spark plug 7 at the center in the combustion chamber 6, and becomes a strong tumble flow.

Further, 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. Then, when the tumble collapses in the latter half of the compression stroke, the flow of the air-fuel mixture is greatly disturbed, causing strong turbulence 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 strong turbulence, thus promoting combustion. For this reason, it becomes possible to burn a lean air-fuel mixture without sacrificing operating performance. Moreover, a large amount of EG can be obtained, and the emission can be reduced.

Next, when the load is high, the opening degree of the throttle valve 10 increases, so that the amount of intake air from the two intake ports 12 and 13 increases. At this time, the suction negative pressure is reduced, so that the assist air B from the tumble port 20 is automatically reduced, so that the above tumble does not occur.

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 two intake valve type engine.

[0018]

[Effect of device]

 As described above, according to the present invention, in the intake system of the engine, the assist air from the inwardly curved portion of the intake port is configured to cause the tumble by causing the intake air to flow unevenly, so that a strong tumble is generated. This improves combustion and improves fuel efficiency. The structure is simple because the tumble port is provided at the inner bent portion of the intake port and the tumble port communicates with the upstream side of the throttle valve. Since the tumble port is formed by machining, the accuracy of the ejection direction and diameter can be improved, and a strong tumble can be generated efficiently.

[Brief description of drawings]

FIG. 1 is a longitudinal 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 a swirling flow of a tumble.

[Explanation of symbols]

 3 Cylinder 10 Throttle valve 12,13 Intake port 12a, 13a Inner curved part 15,16 Intake valve 17 Valve seat 20 Tumble port 21 Passage 25 Mounting hole

Claims (1)

[Scope of utility model registration request] 1. A tumble port is provided in front of an intake valve in an inwardly bent portion of an intake port, so that assist air is ejected in opposition to intake air passing through the port, so that the intake air is biased to the outside bend side of the port. An intake device for an engine, wherein the tumble port communicates with an upstream side of the throttle valve through a passage, and the tumble port is formed into an L shape by a hole machined from a mounting hole of a valve seat.