JPS61232322A - Two cycle internal combustion engine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention provides suction ports that are arranged in a row at the same height on a cylinder wall and whose opening and closing are controlled by a piston, and at least one suction port that is arranged in a cylinder head. The invention relates to a two-stroke internal combustion engine with one exhaust valve.

[Conventional technology]

In the conventional uniflow scavenging system used in this type of internal combustion engine, each intake port is tilted at the same acute angle with respect to its respective radial direction, which creates a force that swirls the intake gas mixture into the cylinder. . However, despite this swirl around the cylinder axis, which is essential for proper combustion, the axial flow across the cylinder is highly non-uniform, with a minimum in the center and a relatively small amount near the cylinder wall. The flow velocity distribution is as follows. This makes the gas emission after combustion non-uniform in the cross-cylinder direction,
Therefore, in order to satisfactorily scavenge the inside of the cylinder, it is necessary to introduce a considerably excessive amount of air, which causes malfunction of the internal combustion engine. - [Problems to be solved by the invention] In view of the above-mentioned circumstances, the purpose of the present invention is to solve the conventional problems,
In other words, it is an object of the present invention to provide a two-stroke internal combustion engine that provides a uniform flow velocity throughout the cylinder transverse direction and has a rectangular flow velocity distribution graph in the longitudinal section of the cylinder.

[Means for solving problems]

The above problem is to provide at least two types of suction ports that make different acute angles between the central axis of the cylinder and a straight line perpendicular to the cylinder, and one type of suction port is located near the cylinder wall, and the other suction port is located near the cylinder wall. This can be solved by selecting the size of the acute angle and slanting it so as to scavenge air from the center of the cylinder. Experimental results have shown that this configuration provides the most uniform scavenging in the cylinder, without requiring any additional air introduction or extra power for scavenging.

The optimum value of the acute angle of the above two types of suction ports can be easily determined through experiments.

More specifically, at least one of the two suction ports, preferably the one for scavenging air near the cylinder wall, generates a swirling flow in the gas within the cylinder, and the other suction ports assist this swirling flow or It is considered to be a power shape that is either neutral, unrelated to the flow, or has a counteracting effect on the liquid flow. In this way, the combustion process can be optimized as desired.

In internal combustion engines of the type where a combustion recess or combustion chamber is formed in the piston and fuel is injected directly into the combustion chamber, there is a suction port located near the bottom dead center of the piston that is used to scavenge air from the center of the cylinder. The recess is formed at an acute angle toward the recess or combustion chamber. The ideal acute angle (that is, the angle of inclination) for this type of machine can also be found through experiments, depending on various factors for each model.

When viewed in longitudinal section of the cylinder, the angle between it and a straight line perpendicular to its axis is in the range of 35° to 75° for the suction port for scavenging air near the cylinder wall, and for the suction port for scavenging air in the center of the cylinder. The best results are obtained when is in the range -30° to +35' (negative values indicate a downward slope).

In a preferred embodiment of the present invention, an intersection point between the center axis of the suction port and the cylinder inner wall surface, which extends approximately toward the center of the cylinder when viewed in the cross section of the cylinder, is considered, and a straight line connecting the intersection point and the cylinder center axis line is defined as the above-mentioned straight line. The angle between the suction port and the center axis of the port is within the range of 0@~406 for the first type of suction port for scavenging near the cylinder wall,
Also, for the second type for scavenging air in the center of the cylinder, -30° to +30° (minus values indicate that the second type of suction port is in the direction opposite to the swirling of the gas in the cylinder by the first type of suction port). Each is set within the range of (meaning that it has been opened).

In order to equalize the velocity distribution of the gas flow along the cylinder axis direction, the above two types of suction ports should be arranged alternately, one at a time, or two of each type in pairs. It's convenient. For manufacturing purposes, it is convenient if the axes of the two suction ports forming the pair are parallel.

In order to scavenge the cylinder and swirl the unburned mixed gas sucked into the cylinder, it is desirable that the suction port has a tapered shape that becomes narrower toward the center of the cylinder.

[For production]

Since the above-mentioned first type of suction port is formed upward at a relatively steep angle with respect to the cylinder wall, the mixed gas sucked through the port 8 flows upward along the cylinder wall, and the gas mixture is flowed upward along the cylinder wall. Sweep the air. On the other hand, since the second type of suction port is formed downward or upward at a relatively gentle angle, or almost horizontally, the mixed gas sucked through the port reaches the cylinder axis, and therefore the piston rises. It works together with the cylinder to scavenge air in the center of the cylinder. Since both types of suction ports are arranged alternately, there is no fear that the suction airflows in different directions as described above will interfere with each other. If either of the two types of suction ports, especially the first type, does not pass through the center of the circular cylinder cross section, but is formed slightly obliquely,
The intake gas mixture swirls within the cylinder.

〔Effect of the invention〕

As described above, in the uniflow type two-stroke internal combustion engine of the present invention, during the exhaust/intake cycle after compression/explosion, the mixed gas from each intake port has a uniform velocity throughout the cylinder transverse direction. It rises towards the cylinder head under the distribution. Therefore, the combustion exhaust gas generated by the explosion in the previous cycle is also pushed up with a uniform velocity distribution over the entire cross section of the cylinder and flows out from the exhaust valve in an orderly manner, resulting in ideal scavenging. In this way, the amount of combustion exhaust gas remaining in the cylinder is kept to a minimum, ensuring that the next cycle's explosion occurs with maximum explosive force, making the internal combustion engine significantly more energy efficient. improves. Since the amount of unburned gas discharged outside the cylinder is also reduced, the internal combustion engine of the present invention is also beneficial from the viewpoint of preventing air pollution.

Incidentally, since it is only necessary to change the shape, mainly the angle, of the suction port provided in the cylinder wall, the present invention is easy to implement and does not result in an increase in manufacturing cost.

〔Example〕

First, for convenience, the prior art will be explained first with reference to FIGS. 1 and 2.

This two-stroke internal combustion engine has a cylinder (1), a piston (
2), a cylinder head (3) and an exhaust valve (4). The suction port (5) is controlled to open and close by a piston.
They are arranged at approximately equal intervals on a line parallel to the upper surface (2'') of the piston (2), and in cross section, are connected to the radial straight line (7) facing the central axis (6) of the piston and the above-mentioned suction port. It forms an angle β with the center line of the suction port (5
) are all the same, a swirling flow about the central axis (6) is generated in the air-fuel mixture gas sucked into the cylinder. The flow in the direction along the central axis scavenges the air inside the cylinder, and this is represented by a vector (8) over the entire cross section of the cylinder, and the component in the direction of the central axis (6) has the sign (9). ).

Regarding component (9), the flow velocity is the minimum near the piston center axis (6), the flow velocity is relatively small even near the cylinder wall, and the flow velocity is maximum at approximately % of the cylinder diameter. Such a significant variation in the axial flow velocity is an unfavorable phenomenon for scavenging air in the cylinder.

Next, an embodiment of the internal combustion engine of the present invention will be explained with reference to FIGS. 3 and 4. This engine eliminates the above-mentioned drawbacks of the conventional engine and has an extremely uniform mixed gas flow velocity distribution (11) in the cylinder axis direction.
is giving. This feature is characterized by arranging two types of suction ports (a) and (b) of the first and second types, and a straight line (12) passing through the suction ports perpendicular to the cylinder axis (6) in the longitudinal section, and a straight line (12) passing through the suction ports. Port center line (a'), (b
') form different acute angles (α') and (-β'). On the other hand, if we look at the cross section perpendicular to the axis (6), the suction bow) (a), (
Since the center lines (a') and (b') in b) all coincide with the radial direction centripetally, no swirling motion occurs in the mixed gas sucked into the cylinder.

Since the above-mentioned first type suction port (a) is formed at a relatively steep angle, scavenging near the cylinder wall is mainly performed by intake air from this suction port (a), whereas the second type suction port (a) Suction bow 1- (b) with a gentle angle of
The intake air mainly contributes to scavenging in the cylinder center area, that is, in the vicinity of the axis (6). The above acute angle (α′), (
-β') is determined so as to obtain a flow velocity distribution as uniform as possible over the entire cylinder cross section.

The above notation of -β' (minus β') means that the second type of suction port (b) is formed downward towards the bottom of the cylinder, which allows the piston (
2) The combustion chamber (13) formed at the top is subjected to complete scavenging action. At the illustrated position of the piston (2), that is, bottom dead center, the suction ports (a), (b) and the exhaust valve (
4) is completely open. The mixed gas flows into the cylinder as shown by the arrow through the suction port and is scavenged with a uniform flow velocity distribution, so the combustion exhaust gas is forced out through the exhaust valve (4) into the exhaust pipe (4"). .Then, open the exhaust valve (4
) closes, and the mixed gas sucked into the cylinder is compressed by the rise of the piston, and at this time, the suction port (a)
, (b) is closed.

[Another example]

In another embodiment shown in FIGS. 5 and 6, the center lines (a") and (b') of the suction ports (a) and (b) in the cross section
does not pass through the cylinder center axis, and the radial straight line (7) connecting these ports and the center axis is connected to the center line (a'
) and (b'') in that included angles (α) and (β) are formed between them.The suction ports are approximately equal in the circumferential direction. arranged at intervals, of the first type (a) and of the second type (b)
and alternately, and their center lines (a'), (b'')
are formed in parallel. Since the inclination of the first type of suction port (a) is large as shown by the angle (α), the swirling flow (14
) occurs. On the other hand, the second type of suction port (b) has a smaller angle (β) between its center line (b) and the straight line (7), so the swirling flow (14) is smaller.
) gives a moment in the direction of a slight rebellion.

In this way, many minute vortices are generated in the swirling flow (14), and the scavenging between the combustion chamber at the top of the piston and the center of the cylinder is further improved.

It is more preferable if each suction port (a) and (b) is formed into a tapered shape that becomes narrower as it approaches the inside of the cylinder, as shown in FIGS. 7 and 8. The top inner surface of each port wall (
15), (16) and the lower inner surface (17), (18)
) are all different angles (α′), (β′); (α′
).

(β″).The angle that typically represents these is the angle (α ').

(β″). This nozzle-like intake port further improves the scavenging of air within the cylinder, since the directionality of the intake air from each port is enhanced.

[Brief explanation of drawings]

1-2 show the prior art, of which FIG. 1 is a longitudinal sectional view, FIG. 2 is a cross-sectional view taken along the line nn in FIG. 1, and FIGS. Embodiments are shown, of which FIG. 3 is a vertical cross-sectional view of the first embodiment, and FIG. 4 is a cross-sectional view of the first embodiment.
5 is a longitudinal sectional view of another embodiment, FIG. 6 is a sectional view taken along the line Vl-Vll in FIG. 5, and FIGS. 7 and 8 are main points of still another embodiment. FIG. (1)...Cylinder, (2)...Piston, (3)...Cylinder head, (4)...
...exhaust valve, (6) ...center axis, (12
)... Straight line, (a)... First type suction port, (b)... Second type suction port, (α'), (β ″）・・・Acute angle. Fig, I Fig, 3Fi 婬
FignuFig, 5 Koga

Claims (1)

[Claims] [1] Suction ports are opened in the wall of the cylinder (1) in a circumferential row at substantially the same height, and the opening and closing of these suction ports is controlled by the piston (2). It is a thing,
At least one exhaust valve (4) is located in the cylinder head (3)
In an internal combustion engine formed in , respectively, form different acute angles (α') and acute angles (β') with the straight line (12) perpendicular to the cylinder center axis (6) in the longitudinal section, and these acute angles form the first type of suction port ( a) is selected to supply a mixture of gases into the cylinder (1) in order to scavenge the vicinity of the cylinder wall, and the second type of suction port (b) to scavenge the center of the cylinder; A two-stroke internal combustion engine characterized by the following. [2] Either one of the first type suction port (a) and the second type suction port (b) crosses in order to generate a swirling flow in the mixed gas sucked into the cylinder. According to claim [1], the suction port is formed with an angle of inclination on the plane, and the other suction port is formed with an angle that acts to support, neutralize, or inhibit this swirling flow. The two-stroke internal combustion engine described. [3] The two-stroke internal combustion engine according to claim [2], wherein the first type of intake port (a) generates the swirling flow. [4] The piston (2) has a combustion chamber (13) at its top.
The second type of intake port (b) near the bottom dead center of the piston is formed downward to scavenge air in the combustion chamber, and the acute angle (β') has a negative value (-β ') Claim No. [1]
The two-stroke internal combustion engine according to any one of paragraphs to [3]. [5] The acute angle (α') of the first type of suction port (a) is 35° to 75°, and the acute angle (β') of the second type of suction port (b) is -30°. The two-stroke internal combustion engine according to any one of claims [1] to [4], wherein the angle is between +35° and 35°. [6] The angle that the above-mentioned suction port makes with respect to the straight line connecting the cylinder center axis and the point where the center line of the above-mentioned two types of suction ports intersects with the cylinder inner wall surface in the cylinder cross section is the first type. An angle (α) of 40° for the suction port (a) of the second type and an angle (β) of −30° to +30° for the second type of suction port (b) The two-stroke internal combustion engine according to any one of Items [3] to [3]. [7] Claim No. 1, wherein the two types of suction ports (a) and (b) are alternately arranged one by one.
The two-stroke internal combustion engine according to any one of paragraphs to [6]. [8] The above two types of suction ports (a), (b)
A two-stroke internal combustion engine according to any one of claims [1] to [6], wherein the two-stroke internal combustion engine is arranged alternately in pairs. [9] The different types of suction ports that are adjacent to each other (
The two-stroke internal combustion engine according to claim 7 or 8, wherein a) and (b) have center lines parallel to each other. [10] At least some of the suction ports (a) and (b) are formed in a tapered shape that becomes narrower as it approaches the inner wall surface of the cylinder.
The two-stroke internal combustion engine according to any one of paragraphs to [9].