JPH04318225A - Air intake controller for multi-valve engine - Google Patents

Abstract

PURPOSE:To generate longitudinal swirl completely with three air intake valves provided, blow into a large amount of intake air around an ignition plug, and improve low-speed and low-load fuel by stabilizing lean air-fuel ratio combustion. CONSTITUTION:An ignition plug 9 is arranged in the roughly center of a combustion chamber, and three air intake valve openings 4c, 4c' and two exhaust valve openings 4d are formed so as to surround the ignition plug 9. Moreover, the air intake valve openings 4c at the right and left side parts and the air intake valve opening 4c' in the center are led out to a cylinder outer wall through an air intake passage 17 which one outside connection opening 17a consisting of right and left side part passages 17d and a central passage 17e. In addition, there is disposed an air intake control valve 21 which reduces a passage sectional area at the time of low-speed rotation or low-load operation.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to an intake control device for an engine equipped with an intake control valve that reduces the cross-sectional area of the intake passage during low-speed rotation, and particularly to a multi-valve engine having three intake valves. When adopting this device, the intake control valve is arranged so that it can generate a so-called vertical swirl and blow a large amount of intake air around the spark plug, thereby improving the fuel consumption rate (hereinafter referred to as fuel efficiency). Concerning improved positioning.

0002

[Prior Art] In order to improve the fuel efficiency of an engine, by increasing the flow velocity of intake air even when the amount of intake air is small, such as during low speed rotation or low load operation, a vertical swirl is generated in the combustion chamber to reduce the leanness. It is effective to stabilize the air-fuel ratio combustion. Conventionally, as an intake control device capable of generating such a vertical swirl, as disclosed in Japanese Patent Publication No. 59-5767, a control plate is arranged movably in the vicinity of the intake valve opening of the intake passage, and There are some systems in which the control plate is raised to narrow down the area of the intake passage during low load operation.

0003

[Problem to be Solved by the Invention] Recently, a five-valve engine with three intake valves and two exhaust valves has been proposed in order to increase the intake and exhaust valve opening areas. It is conceivable that the intake air control device disclosed in the above-mentioned prior art publication may also be employed in other types of engines. However, in this multi-valve engine equipped with three intake valves, by adopting the intake control device of the above-mentioned conventional publication as is, even if the three intake valve opening passages are narrowed down equally, it will not contribute much to improving fuel efficiency. It has been found.

The present invention has been made in view of the above-mentioned conventional situation, and when three intake valves are provided, it is possible to reliably generate a vertical swirl and blow a large amount of intake air around the spark plug. The present invention aims to provide an air intake control device for a multi-valve engine that can stabilize lean air-fuel ratio combustion and improve low-speed, low-load fuel efficiency.

[0005]

[Means for Solving the Problems] The present invention arranges a spark plug approximately in the center of a combustion chamber, and forms three intake valve openings and a plurality of exhaust valve openings to surround the spark plug. , the intake valve opening on the right side and the intake valve opening in the center are guided to the cylinder outer wall by an intake passage consisting of left and right side passages and a center passage and having one external connection opening, and each of the left and right side passages The present invention is characterized in that an intake control valve is provided to reduce the cross-sectional area of the passage during low-speed rotation or low-load operation.

[0006]

[Operation] According to the intake control device of the present invention, when the amount of intake air is small, such as during low speed rotation, the intake control valves disposed in the left and right side passages of the intake passage move to the closed position. This reduces only the passage cross-sectional area of the left and right side passages. As a result, the overall flow velocity of the intake air increases, a vertical swirl is generated by the intake air from the left and right intake valve openings, and a larger amount of intake air is blown into the center of the combustion chamber from the center intake valve opening. As a result, the air-fuel mixture around the spark plug located in the center of the combustion chamber is sufficiently stirred, and lean air-fuel ratio combustion is stably performed, improving low-speed, low-load fuel efficiency.

[0007]

Embodiments Hereinafter, embodiments of the present invention will be explained with reference to the drawings. 1 to 5 are diagrams for explaining an intake control device for a five-valve engine according to an embodiment of the present invention.

In the figure, 1 is a water-cooled 4-cycle parallel 4
It is a 5-cylinder engine with 5 valves, and this has 2 crankcases.
A cylinder block 3 and a cylinder head 4 are stacked on top of each other in a forward-inclined state and connected with head bolts.
It has a structure in which a head cover 5 is placed over the upper mating surface of the head. A piston 7 is slidably inserted into each of the four cylinder bores 3a formed in the cylinder block 3, and each piston 7 is connected to a crankshaft (not shown) via a connecting rod 8.

A combustion recess 4b constituting a combustion chamber is provided on the lower mating surface 4a of the cylinder head 4 on the cylinder block 3 side.
is recessed. An ignition plug 9 is screwed into the center of the combustion recess 4b, and around the plug 9 there are left,
right side intake valve openings 4c, 4c, center intake valve opening 4c',
and exhaust valve openings 4d, 4d are open. A valve plate 10a of the exhaust valve 10 is arranged in each exhaust valve opening 4d, and a valve plate 11a of the intake valve 11 is arranged in each intake valve opening 4c, 4c' so that the openings 4d, 4c, 4c' can be opened and closed. ing. The valve shafts 10b and 11b of the exhaust and intake valves 10 and 11 extend obliquely in the cylinder axis direction so as to form a predetermined included angle when viewed in the camshaft direction, and an exhaust and intake lifter 1 is provided at the upper end thereof.
2 and 13 are installed respectively. each lifter 12,
On 13 are exhaust and intake camshafts 14 and 1 that drive this.
5 are arranged perpendicularly to the cylinder axis and parallel to each other. A cam chain (not shown) connecting the exhaust and intake camshafts 14, 15 and the crankshaft is located in a chain chamber 4 formed at the center of the four cylinder bores 3a.
It is located within e.

The two exhaust valve openings 4d are led out to the front wall 4f of the cylinder head 4 through a bifurcated exhaust passage 16. Although not shown, an exhaust manifold is connected to the wall opening 16a of the exhaust passage 16.
An exhaust control valve for controlling the cross-sectional area of the exhaust passage is disposed at the merging portion of the exhaust manifold.

The three intake valve openings 4c and 4c' are led out to the rear wall 4g of the cylinder head 4 through an intake passage 17. This intake passage 17 has one external connection opening 1
7a, and is composed of left and right side passages 17d, 17d for the left and right side intake valve openings 4c, and a central passage 17e for the central intake valve opening 4c'. . When viewed in the direction of the cylinder axis, the intake passage 17 as a whole extends substantially perpendicular to the camshaft, and when viewed in the direction of the camshaft, it bends in an arc shape from the intake valve opening 4c toward the cylinder rear wall 4g. It extends approximately in a straight line. A carburetor 19 is connected to the external connection opening 17a of the intake passage 17 via an intake manifold 18. This intake manifold 18 is an integrated structure of a holding bracket 18a and a carburetor joint 18b for holding an intake control valve drive mechanism, which will be described later.
8a is connected and fixed to the external connection opening 17a, and a discharge port of the carburetor 19 is connected and fixed to the carburetor joint 18b. This carburetor 19 has a butterfly type throttle valve 19a that opens and closes when the throttle is operated, and a piston valve 19 that automatically opens and closes using the engine's intake negative pressure.
It is of an automatically variable venturi type having b. Further, an air cleaner 20 is connected to the suction port 19c of the carburetor 19.

A valve hole 17c is formed in the bottom wall portion of the left and right side passages 17d, 17d of the intake passage 17 so as to open in the direction of the passage and into the bottom wall surface. When viewed in the direction of the cylinder axis, the left and right side passages 17d and 17d are slightly inclined inward so that the outer side is located closer to the inside, whereas the valve hole 17c is formed by a straight line connecting the cylinder axis. (see Figure 1). On the other hand, when viewed in the camshaft direction, it is slightly inclined so that the downstream side of the intake passage 17 is positioned further inward of the intake passage (see FIG. 2).

In the left and right valve holes 17c, an intake control valve 21 for changing the cross-sectional area of the left and right side passages 17d, 17d is rotatably disposed about its axis. . As shown in FIG. 1, the intake control valve 21 and the intake passage 17 are inclined relative to each other by an angle θ. Therefore, as shown in FIGS. 3 and 4, the amount of deviation D between the two is It gets bigger towards the sides. The intake control valve 21 is formed by cutting out a U-groove-shaped intake recess 21a over the entire length of a round rod, and forming an inclined surface 21c at the tip and a pinion 21b at the rear end. . The intake recess 21a forms a continuous surface with the wall surfaces of the left and right side passages 17d when the control valve 21 is rotated to the fully open position. Further, when the control valve 21 is rotated to the fully closed position, since the valve hole 17c is oblique to the left and right side passages 17d as described above, the passage cross-sectional area of the left and right side passages 17 is is gradually narrowed (see Figs. 2 to 4).

A slide hole 18c is formed in the holding bracket 18a of the intake manifold 18 in a direction perpendicular to each of the control valves 21. A drive shaft 22 having a rack 22a is slidably inserted into the slide hole 18c, and the pinion 21b of the control valve 21 meshes with the rack 22a.

Although not shown, the drive shaft 22
One end of a drive arm that is pivotally supported by the holding bracket 18a is connected to the outer end of the drive arm, and the other end of the drive arm is connected to a drive motor via a drive cable. Further, the above-mentioned exhaust control valve is also connected to the above-mentioned drive motor via a drive cable, and the drive of this drive motor is controlled by a control unit.

Next, the effects of this embodiment will be explained. When the amount of intake air is small, such as when the engine rotates at low speed or when operating under low load, the intake control valve 21 disposed in the left and right side passages 17d is in the closed position, as shown in FIGS. 2 to 4. The cross-sectional area of only the left and right side passages 17d is reduced. This increases the overall flow velocity of the intake air, and the intake air flowing through the left and right side passages 17d flows along the ceiling wall surface and flows from the left and right side intake valve openings 4c at a high flow rate and with a downward direction. It is blown into the combustion chamber, ensuring vertical swirl. In addition, since only the left and right side passages 17d are narrowed down, a relatively large amount of intake air is blown into the center of the combustion chamber from the center intake valve opening 4c', and the air-fuel mixture around the spark plug 9 located in the center is Stir well. From these points, lean air-fuel ratio combustion is performed stably, resulting in improved fuel efficiency during low-speed rotation and low-load operation.

Furthermore, in this embodiment, the intake control valve 21 is made into a rod-shaped body and is disposed in the direction of the intake passage, so that the area of the intake passage gradually decreases, thereby increasing the equivalent pipe length.
The filling efficiency during low-speed rotation is improved, and the low-speed torque increases accordingly.

When the amount of intake air is large, such as when the engine is running at high speed or under high load, the intake control valve 21
is rotated to the fully open position, whereby the intake recess 21a forms a continuous surface with the wall surfaces of the left and right side passages 17d (Figs. 3 and 4).
), the intake control valve 21 does not cause intake resistance. In the above embodiment, the intake control valve is a circular rod-shaped body and arranged in the direction of the intake passage, but the shape and arrangement direction of the intake control valve in the present invention are not limited to the above embodiments. The intake control valves may be arranged only in the left and right side passages, facing in a direction perpendicular to the intake passage. Further, plate-shaped control valves such as those described in Japanese Patent Publication No. 59-5767 may be arranged only in the left and right side passages.

[0019]

As described above, according to the intake control device for a multi-valve engine according to the present invention, the intake control valves are arranged only in the left and right side passages, so that during low speed rotation, etc. Only the right side is throttled, and this allows the intake air from the left and right side passages to generate a vertical swirl, and also allows a large amount of intake air from the center passage to be blown around the spark plug, reducing the airflow from these points. It has the effect of stabilizing the air-fuel ratio combustion and improving fuel efficiency during low-speed rotation, low-load operation, etc.

[Brief explanation of drawings]

FIG. 1 is a sectional view taken along the line II in FIG. 2;

FIG. 2 is a cross-sectional side view of an intake control device for a five-valve engine according to an embodiment of the present invention.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is a bottom view of the cylinder head of the above embodiment.

[Explanation of symbols]

1 Engine 4b Combustion recess (combustion chamber) 4c Left and right side intake valve openings 4c' Central intake valve opening 4g　Cylinder rear wall (outer wall) 9 Spark plug 17 Intake passage 17a External connection opening 17d Left and right passages 17e Central passage 21 Intake control valve

Claims (1)

[Claims] Claim 1: A spark plug is disposed approximately in the center of the combustion chamber, and three intake valve openings and a plurality of exhaust valve openings are formed to surround the spark plug, and each of the left, right and center The intake valve opening is guided to the outer wall of the cylinder through an intake passage consisting of left and right side passages and a central passage and having one external connection opening, and a passage is provided in each of the left and right side passages during low speed rotation or low load operation. An intake control device for a multi-valve engine, characterized by having an intake control valve that reduces the cross-sectional area.