JPH0263090B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an intake system for an internal combustion engine.

(Prior Art) Conventionally, there is an internal combustion engine called a counterflow type.

In this internal combustion engine, an intake passage and an exhaust passage of a cylinder are provided in parallel and adjacent to each other in a cylinder head.

Further, the valve shaft of the intake valve is arranged on the downstream side of the intake passage so as to intersect with the flow of intake air.

However, in the above-mentioned internal combustion engine, the passage area on the downstream side of the intake passage is restricted by the valve shaft of the intake valve disposed there, its guide, etc.
There has been a problem in that the maximum intake amount of the internal combustion engine in the high-load operating range is often determined by the valve stem. One possible solution to this problem is to enlarge the intake passage at the part where the valve stem is located, but in the case of a counterflow internal combustion engine, the intake passage is located adjacent to the exhaust passage as described above, so When the intake passage is enlarged, it interferes with the exhaust passage, making it extremely difficult to enlarge the intake passage.

(Problems to be Solved by the Invention) The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an auxiliary intake passage on the downstream side of the valve shaft of the intake valve in the intake passage as an intake passage and an exhaust passage. By communicating without interference, the intake passage can be expanded indirectly, and the amount of air taken into the cylinder can be increased, thereby improving the output performance of the internal combustion engine.

(Means for Solving the Problems) In order to solve the above-mentioned problems, an intake system for an internal combustion engine according to the present invention has an intake passage and an exhaust passage arranged in parallel and adjacent to each other in a cylinder head. In a counterflow type internal combustion engine, in which the valve shaft of the intake valve is provided to extend toward one side and is located downstream of the intake passage so that the valve shaft of the intake valve intersects with the flow of intake air, the valve shaft in the intake passage An auxiliary intake passage is communicated with the downstream side of the cylinder head and extends toward the other side of the cylinder head.

(Example) An example of carrying out the present invention will be described with reference to the drawings regarding an intake system for a so-called counterflow type internal combustion engine. In the drawing, A is an internal combustion engine, 1 is a cylinder, 2 is a cylinder head, and 3 is a piston.

The internal combustion engine A has a plurality of cylinders a, and an intake passage 4 and an exhaust passage 5 are formed in the cylinder head 2 of each cylinder a.

The intake passage 4 and the exhaust passage 5 are arranged adjacent to each other in parallel in the cylinder head 2, and are provided so as to extend toward one side of the cylinder head 2, and are bent at the downstream side to form an intake port 6 and an exhaust port. 7
It is connected to the combustion chamber 8 via.

Reference numeral 9 denotes a recess formed in the lower surface of the cylinder head 2, and the combustion chamber 8 is formed between this recess 9 and the upper end of the piston 3 located at the top dead center.

10 is an intake valve that opens and closes the intake port 6, and 11 is an exhaust valve that opens and closes the exhaust port 7.

These intake and exhaust valves 10 and 11 have valve heads 10a and 11
a faces into the combustion chamber 8 corresponding to the intake and exhaust ports 6 and 7, and valve shafts 10b and 11b are arranged so as to intersect with the intake and exhaust flows on the downstream side of the intake passage 4 and the exhaust passage 5, respectively. It is slidably supported on the wall surface of the cylinder head 2 via 12.

Reference numeral 13 denotes a valve operating cam device for driving the intake and exhaust valves 10 and 11, and is housed in a cover 14 connected to the upper end of the cylinder head 2.

Reference numeral 15 designates a conventionally known composite carburetor connected to the upstream side of the intake passage 4 of each cylinder a via an intake manifold 16, and this single carburetor 15 supplies intake air to each cylinder a. It's becoming like that.

23 is a primary throttle valve that is manually operated in the carburetor 15, and 24 is a secondary throttle valve that opens in a higher-than-scheduled high-load operating range of the internal combustion engine A.

Control valves 17 are provided on the downstream side of the intake manifold 16, that is, on the branch pipe portions 16a leading to each cylinder a, and they open and close in conjunction with the primary throttle valve 23, and even when they are in the most closed position, they open and close to some extent. The opening amount is ensured.

In such an internal combustion engine A, the passage area on the downstream side of the intake passage 4 in each cylinder a is equal to the valve shaft 10b of the intake valve 10.
There is a problem that the intake air flow is restricted and reduced by the guide 12, and the flow of intake air is obstructed by them, resulting in a reduction in the amount of intake air into the cylinder 1.

Therefore, as a means to solve this problem, an auxiliary intake passage 18 is provided on the downstream side of the valve shaft 10b in the intake passage 4.
is communicated.

The auxiliary intake passage 18 is set to have a smaller passage area than the intake passage 4, and the valve axis of the intake valve 10 is formed on the wall surface corresponding to the rear side of the valve shaft 10b in the flow direction on the downstream side of the passage 4, that is, on the wall surface 4a on the outside in the bending direction. 10a
The opening is slightly deviated outward. Further, the sub-intake passage crosses the intake passage 4 and the intake port 6
It faces the outer peripheral part of the combustion chamber 8, that is, in the tangential direction of the cylinder 1 and toward the upper surface of the piston 3, and also extends toward the other side of the cylinder head 2, which is opposite to the intake passage 4 and the exhaust passage. There is.

The auxiliary intake passage 18 of each cylinder a is connected to a communication pipe 21 via a short pipe 19 and a connecting pipe 20, respectively.

This communication pipe 21 has a length spanning each cylinder a of the internal combustion engine A, and by connecting the auxiliary intake passage 18 to the pipe 21 as described above, the intake passage 4 of each cylinder a is communicated with each other. It's getting old.

Therefore, since the phases of the intake strokes in each cylinder a of the internal combustion engine A are different, the intake air from the intake passage 4 of the cylinder a remaining in the cylinder 1 of the cylinder a which is in the intake stroke is different from the intake air from the intake passage 4. Intake air is supplied through the auxiliary intake passage 18, and the amount of intake air into the cylinder 1 is increased.

This increase in the amount of intake air is particularly effective in the high-load operating range of the internal combustion engine A.

In addition, in the low-load operation range including idling operation, the control valve 17 is throttled as shown in FIG. Supplied via.

Due to the small passage area of the passage 18, the intake air from the sub-intake passage 18 flows from the intake port 6 into the cylinder 1 at high speed in the tangential direction thereof, and forms a vortex flow within the cylinder 1.

This vortex flow of intake air within the cylinder 1 is maintained until the end of the compression stroke, and has the effect of causing the intake air to be combusted in the combustion chamber 8 at high speed and stably, thereby improving combustion efficiency.

Since the internal combustion engine A has a plurality of cylinders a, the auxiliary intake passage 18 is oriented in the opposite direction to the intake passage 4 in each cylinder a so as not to interfere with each other.

Next, FIG. 3 shows another embodiment.

In this embodiment, the communication pipe 21 in the previous embodiment is connected to the downstream side of the primary throttle valve 23 and the secondary throttle valve 24 of the carburetor 15 via a pipe line 22, thereby connecting the auxiliary intake passage of each cylinder a. 18 is intake passage 4
It is directly connected to the carburetor 15, bypassing the upstream control valve 17.

The control valve 17 is designed to be fully closed in a low-load operating range including idling operation of the internal combustion engine A.

Further, since the structure of other parts in this embodiment is the same as in the previous embodiment, they are indicated by the same reference numerals in the drawings, and explanations thereof will be omitted.

Therefore, in this embodiment, in a low-load operating range including idling operation of the internal combustion engine A, the control valve 17 upstream of the intake passage 4 is fully closed, and the primary throttle valve 23 of the carburetor 15 is kept at a low opening. As a result, all intake air is supplied through the sub-intake passage 18.

That is, a large amount of intake air is supplied at high speed to the cylinder 1 of cylinder a in the intake stroke exclusively from the carburetor 15 directly through the auxiliary intake passage 18, and a stronger intake vortex is created in the cylinder 1 than in the previous embodiment. This can further improve combustion efficiency.

Note that, in the high-load operating range, the amount of intake air is increased by intake air from the auxiliary intake passage 18, as in the previous embodiment.

(Effects of the Invention) As described above, the present invention connects the auxiliary intake passage to the downstream side of the valve stem of the intake valve in the intake passage, so it is suitable for so-called counterflow type internal combustion engines in which it is difficult to expand the intake passage. The intake passage is indirectly expanded by the auxiliary intake passage, thereby increasing the amount of intake air into the cylinder in a high-load operating range, thereby improving the output performance of the internal combustion engine.

In addition, since both the intake and exhaust passages and the auxiliary intake passage are provided separately on one side and the other side of the cylinder head,
The auxiliary intake passage and both the intake and exhaust passages can be arranged without interfering with each other, and furthermore, the intake air from the auxiliary intake passage described above crosses the intake air flowing into the cylinder from the intake passage and flows into the cylinder. Since two vortex flows are generated within the cylinder, combustion can be carried out at high speed and stably.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view showing the intake device of the present invention, Fig. 2
The figure is a view in the direction of arrow ( ) in FIG. 1, and FIG. 3 is a longitudinal sectional view showing another embodiment. In the figure, A... Internal combustion engine, a... Cylinder, 1...
Cylinder, 2...Cylinder head, 4...Intake passage, 5...Exhaust passage, 10...Intake valve, 10b...
...Intake valve stem, 18...Sub-intake passage.

Claims (1)

[Claims] 1. An intake passage and an exhaust passage are arranged adjacent to each other in parallel in the cylinder head, and extend toward one side of the cylinder head, and the valve shaft of the intake valve is provided on the downstream side of the intake passage. An intake system for a counterflow internal combustion engine positioned to intersect with the flow of intake air, in which a sub-intake passage is communicated with the downstream side of the valve shaft in the intake passage and extends toward the other side of the cylinder head.