JPH07180560A - Suction device for internal combustion engine - Google Patents

Abstract

PURPOSE:To smoothly guide the flow of intake air throttled by a swirl control valve to a combustion chamber. CONSTITUTION:Formation of a suction device for an internal combustion engine is such that a swirl control valve 1 rotatably supported through a rotary shaft is arranged in a suction passage 2 and a notch part 5 through which intake air flows is formed in the swirl control valve 1 in a state to offset from the central line of the suction passage 2. A guide groove 6 positioned facing the notch part 5 and dented approximately in parallel to the central line of the suction passage 2 is formed in the suction passage 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an intake system for an internal combustion engine.

[0002]

2. Description of the Related Art As a method of obtaining stable combustion even at low speed, it is effective to generate an appropriate swirl (swirl flow) in the combustion chamber.

As a device for producing a swirl, for example, as disclosed in Japanese Utility Model Laid-Open No. 2-92030, there is a device provided with a swirl control valve that throttles intake air sucked into a combustion chamber according to operating conditions.

As a conventional swirl control valve, there is a swirl control valve that is rotatably supported in an intake passage via a rotary shaft and has a notch formed at one end thereof offset from the center line of the intake passage. When the swirl control valve is closed, the intake air sucked into the combustion chamber is throttled to increase the flow velocity of the intake air sucked into the combustion chamber from the intake port to generate swirl in the combustion chamber.

[0005]

However, the cross-sectional shape of such a conventional intake passage is formed symmetrically on the side where the notch of the swirl control valve is open and the side where the notch is not open. Therefore, the flow of intake air collected in the notch of the swirl control valve cannot be smoothly guided to the combustion chamber, and there is a problem that the swirl cannot obtain sufficient power.

In view of the above problems, the present invention has an object of smoothly guiding the flow of intake air throttled by a swirl control valve into a combustion chamber in an intake system of an internal combustion engine.

[0007]

The invention according to claim 1 is
A swirl control valve rotatably supported in the intake passage via a rotary shaft is provided, and a notch portion for passing intake air when the swirl control valve is closed is formed by being offset from the center of the intake passage. In the intake device, a guide groove is formed in the intake passage so as to face the notch and to be recessed substantially parallel to the center line of the intake passage.

[0008]

In the invention described in claim 1, the guide groove expands the cross-sectional area of the intake passage on the side where the cutout portion of the swirl control valve of the intake passage opens, so that the intake air gathered in the cutout portion of the swirl control valve. The flow of is smoothly guided to the outer peripheral portion of the combustion chamber. As a result, the flow velocity of the intake air sucked into the combustion chamber is increased from the central portion of the combustion chamber to the outer peripheral portion thereof, which causes a strong swirl in the combustion chamber, promotes the mixing of fuel spray and air, and provides good combustion performance. can get.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the accompanying drawings.

In FIGS. 1 and 2, 1 is a swirl control valve, 2 is an intake passage of the engine, and 10 is a combustion chamber. The intake passage 2 is formed with two intake ports 11 that open into the combustion chamber 10 of one cylinder. The intake passage 2 is located upstream of the swirl control valve 1 in FIG.
As shown by the two-dot chain line, it has an oval cross-sectional shape.

The swirl control valve 1 has a rotating shaft 3
It is rotatably supported via. The thin plate-shaped swirl control valve 1 is joined to the inner wall of the intake passage 2 at its fully closed position, or faces the outer peripheral edge portion 4 facing each other with a small gap, and the notch portion 5 for passing intake air away from the inner wall of the intake passage 2. Have and.

When the swirl control valve 1 is in the fully closed position, the cutout portion 5 is located above the rotary shaft 3 and laterally of the intake passage 2, so that the passage center of the intake passage 2 ( The center of gravity Gp is offset and opened.

A guide groove 6 is formed in the intake passage 2 so as to face the notch 5 and to be concave. Guide groove 6 is notch 5
From the immediately downstream side of the portion facing the
Over a portion near the outer peripheral portion of the combustion chamber 10 and extends parallel to the center line of the intake passage 2.

As shown in FIG. 3, a portion of the intake passage 2 immediately downstream of the swirl control valve 1 has a passage wall portion 13 curved with an oval cross section and a guide substantially orthogonal with two linear cross sections. It is defined by the groove side surfaces 14 and 15 and the guide groove bottom surface 16 that connects the guide groove side surfaces 14 and 15 with an arcuate cross section.

In FIG. 3, a straight line G is a line segment connecting the center Gp of the intake passage 2 and the center (center of gravity) Gs of the flow passage defined by the cutout portion 5. The cross section of the guide groove bottom surface 16 is formed by an arc having a center on the line segment G. The radius of curvature of the guide groove bottom surface 16 is set in the range of 3 to 5 mm, for example, and is made smaller at a predetermined ratio with respect to the radius of curvature of the passage wall portion 13.

As shown in FIG. 4, a portion of the intake port 11 close to the outer peripheral portion of the combustion chamber 10 has a passage wall portion 23 having a circular cross section and a guide groove having two linear cross sections which are substantially orthogonal to each other. Guide groove bottom surface 26 that connects the side surfaces 24, 25 and each guide groove side surface 24, 25 with an arcuate cross section
Defined by and.

In FIG. 4, a straight line S is a line segment that passes through the center Gp of the intake passage 2 and intersects the center line C of the cylinder orthogonal to the crankshaft at an angle of 45 °. The cross section of the guide groove bottom surface 26 is formed by an arc having a center on the line segment S. The radius of curvature of the guide groove bottom surface 26 is set within a range of 3 to 5 mm, for example, and is made smaller at a predetermined ratio with respect to the radius of curvature of the passage wall portion 23.

The rotating shaft of the swirl control valve 1 is rotationally driven in accordance with the operating state of the engine by a diaphragm type actuator (not shown) or a step motor. The control device controls the opening degree of the swirl control valve 1 in accordance with the contents of a map preset according to the operating state of the engine.

With the above construction, the operation will be described below.

Under an operating condition such as a low speed, the swirl control valve 1 is closed, and most of the intake air is guided to the one intake port 11 through the cutout portion 5.

The guide groove 6 expands the cross-sectional area of the intake passage on the side where the cutout portion 5 of the intake passage 2 opens, so that the flow of intake air collected in the cutout portion 5 is smoothly conducted to the outer peripheral portion of the combustion chamber 10. invite. As a result, the flow velocity of the intake air sucked into the combustion chamber 10 is increased in the outer peripheral portion than in the central portion of the combustion chamber 10,
A strong swirl is generated in the combustion chamber 10, the mixing of the fuel spray and air is promoted, and good combustibility is obtained.

Next, in another embodiment shown in FIG. 5, the intake port 11 has guide groove side surfaces 24 and 25 in which the cross sections thereof are substantially orthogonal to each other with two linear cross sections, and the guide groove side surfaces 24 and 2 respectively.
A guide groove bottom surface 26 that connects 5 with an arcuate cross section, a passage wall portion 23 that is curved with a circular cross section, and a portion 27 that faces the guide groove 6 with the center Gp of the intake passage 2 interposed therebetween.
And the curvature of the facing portion 27 is made larger than that of the passage wall portion 23 having a circular cross section.

In this case, by expanding the passage cross-sectional area occupied by the guide groove 6 in the intake passage 2, the effect of smoothly guiding the flow of intake air collected in the cutout portion 5 to the outer peripheral portion of the combustion chamber 10 can be enhanced. . As a result, the flow velocity of the intake air sucked into the combustion chamber 10 is increased from the central portion of the combustion chamber 10 toward the outer peripheral portion thereof, a strong swirl is generated in the combustion chamber 10, and the mixing of fuel spray and air is promoted, which is favorable. Flammability is obtained.

In each of the above embodiments, the guide groove 6
Is formed from the immediately downstream side of the portion of the intake passage 2 facing the cutout portion 5 toward the combustion chamber 10, but as another embodiment, from the upstream side of the portion facing the cutout portion 5 to the downstream side. The swirl generated in the combustion chamber 10 can be further strengthened by forming the swirl so that the swirl extends.

[0025]

As described above, according to the first aspect of the present invention, the swirl control valve is rotatably supported in the intake passage via the rotary shaft, and the swirl control valve passes the intake air when the swirl control valve is closed. In an intake device for an internal combustion engine in which the cutout portion is formed offset from the center of the intake passage, a guide groove is formed in the intake passage so as to face the cutout portion and to be recessed substantially parallel to the centerline of the intake passage. By smoothly guiding the flow of intake air collected by the notch part of the swirl control valve to the outer peripheral part of the combustion chamber, a strong swirl is generated in the combustion chamber, promoting the mixing of fuel spray and air at low speed. It is possible to obtain stable combustion from.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an intake passage and the like showing an embodiment of the present invention as seen from above.

FIG. 2 is a sectional view of the intake passage and the like as seen from the front.

FIG. 3 is a sectional view taken along line AA of FIGS. 1 and 2.

FIG. 4 is a sectional view taken along the line BB of FIGS. 1 and 2.

FIG. 5 shows another embodiment of the intake passage shown in FIG. 1 and FIG. 2B.
-A sectional view taken along line B.

[Explanation of symbols]

 1 Swirl Control Valve 2 Intake Passage 5 Notch 6 Guide Groove 10 Combustion Chamber 11 Intake Port 13 Passage Wall 14 Guide Groove Side 15 Guide Groove Side 16 Guide Groove Bottom 23 Passage Wall 24 Guide Groove Side 25 Guide Groove Side 26 Guide Groove bottom 27 Facing part

Claims (1)

[Claims] 1. A swirl control valve rotatably supported in an intake passage via a rotary shaft, wherein a notch for passing intake air when the swirl control valve is closed is offset from the center of the intake passage. In the intake device for an internal combustion engine to be formed, an intake device for an internal combustion engine, wherein a guide groove is formed in the intake passage so as to face the cutout portion and to be recessed substantially parallel to a center line of the intake passage.