JPH0653726U - Engine intake system - Google Patents

Abstract

(57) [Summary] [Purpose] To improve combustion by effectively generating tumble throughout the engine operation with a simple configuration using assist air. [Structure] Intake valve 1 of inner bent portion 12a of intake port 12
Immediately before 3, the tumble port 20 is provided so as to communicate with the intake air in the port.
Communicates with two control ports 22, 23 near the throttle valve 10 via a passage 21. When the load is low and the load is medium or higher, the flow rate of assist air is controlled to be ejected from the tumble port 20 into the intake port 12, and the intake air passing through the port is biased to the outside curve side of the port to enter the cylinder 3. Tumble is generated according to the driving condition.

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, 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.

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 appropriately generate a tumble in the cylinder corresponding to the operating condition throughout the engine operation.

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 has been shown that at low load, the intake port is closed by the on-off valve, only the auxiliary intake passage is inhaled, and this jetted intake air is swirled in the axial direction in the cylinder to generate a vertical swirl (tumble flow).

[0005]

[Problems to be solved by the device]

 By the way, in the above 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 become complicated. Also, under operating conditions above medium load, the amount of air in the auxiliary intake passage is constant, so there is a problem in that sufficient tumble cannot be generated.

The present invention has been made in view of this point, and it is an object of the present invention to effectively generate tumble and improve combustion in a simple configuration using assist air throughout the engine operation.

[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 is connected via a passage to a control port provided near the throttle valve so as to control the flow rate of assist air according to the opening degree of the throttle valve.

[0008]

[Action]

 Based on the above configuration, assist air is sucked out from the tumble port during engine operation, but the pressure difference between the tumble port and the control port changes depending on the throttle opening, which reduces assist air when the load is low. Assist air is controlled to increase above the load. The assist air is jetted into the intake port at high speed, and in either case, the intake air passing through the intake port is diverted to the outward bend side. Flows in the direction. In this way, under all operating conditions, tumbles will be generated in the cylinders corresponding to the operating conditions.

[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 an intake port 12 communicating with this intake manifold 11 is connected to the combustion chamber 6. An intake valve 13 is installed in the intake port 12 so as to be in contact with and separated from a valve seat 14 and opened and closed, and an injector 15 is attached to an end of the intake manifold 11 so as to inject fuel into the intake port 12. There is.

Here, since the intake port 12 is bent and formed substantially at a right angle in a side view, it is possible to generate a tumble by causing the intake air to be deflected to the outer curved side having a large radius of curvature by the assist air. Therefore, the tumbling port 20 is provided so as to communicate with the intake port 12 of the cylinder head 5 immediately before the intake valve 13 of the inner curved portion 12a 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.

On the other hand, in order to control the assist air according to the throttle opening, two control ports 22 and 23 are provided near the throttle valve. That is, the two control ports 22 and 23 are arranged so that they are located upstream and downstream of the throttle valve 10 when the load is small and the throttle opening is small, and both are located upstream of the throttle valve 10 when the load is medium and above. It The tumble port 20 communicates with the two control ports 22 and 23 via the passage 21, and is configured to change the pressure in the passage 21 according to the throttle opening.

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 to be sucked into the cylinder 3, the piston 4 inside the cylinder 3 reciprocates, and a predetermined fuel is injected from the injector 18. To be done. 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 negative suction pressure is applied to the tumble port 20. On the other hand, in this case, the throttle valve is located between the two control ports 22 and 23 so that the atmospheric pressure upstream of the throttle valve 10 is reduced by the negative pressure downstream thereof. As a result, the pressure difference between the passage 21 and the tumble port 20 becomes small, and a relatively small amount of air is sucked in from the upstream side of the throttle valve 10, and this assist air B flows from the injection port 20a of the tumble port 20 into the intake port 12. Gush out.

Therefore, the intake air A passing through the intake port 12 is diverted to the outward curve 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 shown in FIG. Will be suitable for. Therefore, any intake air A from the intake port 12 flows into the cylinder 3 substantially linearly via the exhaust port side regardless of the shape of the port, and thereby enters the inside of the cylinder 3 and the combustion chamber 6. At this point, as shown in FIG. 1, a tumble C that turns in the cylinder axis direction is generated.

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 disturbed, causing 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 combustion speed due to turbulence, thus promoting combustion. Further, in this case, a gentle tumble C is generated by a small amount of assist air B suitable for a low load operating condition. In addition, this also suppresses an increase in idle speed.

Next, under an operating condition in which the opening of the throttle valve 10 is large and a medium load or more, the intake air amount from the intake port 12 increases in accordance with the throttle opening. At this time, since the two control ports 22 and 23 both become equal to the atmospheric pressure upstream of the throttle valve 10, the pressure difference with the tumble port 20 increases, and the flow rate of the assist air B also increases. Therefore, a large amount of intake air A passing through the intake port 12 is effectively biased by the increased flow rate of the assist air B, so that a large amount of intake air A flows in the cylinder 3 in the axial direction to drive the engine. A strong tumble C corresponding to the condition is generated. Therefore, even under these operating conditions, combustion and the like are promoted by the tumble effect as described above.

Another embodiment of the present invention will be described with reference to FIG. In (a), two tumble ports 20 and 24 are provided in the inwardly bent portion 12a of the intake port 12, and each of the ports 20 and 24 is provided with two control ports 22 near the throttle valve by passages 21 and 25, respectively. It is configured to communicate with 23. Therefore, in this embodiment, when the load is low, only one passage 21 is sucked, and when the load is medium or higher, the suction is performed by the two passages 21 and 25, and the flow rate of assist air is similarly controlled. In (b), a control port 26 formed in a long hole is provided near the throttle valve 10, and the atmospheric pressure is similarly changed by this control port 26.

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.

[0019]

[Effect of device]

 As described above, according to the present invention, in the intake system of the engine, the intake air is biased by the assist air from the inner bent portion of the intake port to generate the tumble. Since the flow rate of assist air is controlled according to the conditions, when the load is low, a tumble commensurate with the flow rate is generated to improve combustion and suppress an increase in idle speed. In addition, even at medium load or more, tumble is sufficiently generated and combustion can be improved. The structure is simple because a tumble port is provided at the inner bend of the intake port and this tumble port communicates with the control port near the throttle valve.

[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 cross-sectional view showing another embodiment of the present invention.

[Explanation of symbols]

 3 Cylinder 10 Throttle Valve 12 Intake Port 12a Inner Curved Part 13 Intake Valve 20 Tumble Port 21 Passage 22,23 Control Port

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 a control port provided near the throttle valve via a passage so as to control the flow rate of assist air according to the opening degree of the throttle valve.