JPS587057Y2 - 2-stroke internal combustion engine - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to a two-stroke internal combustion engine.

In conventional internal combustion engines of the so-called schnule-type scavenging force type, in which a pair of scavenging ports connected to the crank chamber are provided facing each other on the inner surface of the cylinder, this method improves scavenging in the area between the scavenging ports on the opposite side from the exhaust port. Therefore, it is known that an auxiliary scavenging port is provided above the intake port.

By the way, this sub-scavenging port naturally has to communicate with the crank chamber, but if this communication passage is provided by bypassing the intake passage, there is a problem that the structure of the cylinder becomes complicated and its manufacturing cost increases.

Also, if the communication passage is connected to the intake passage and the crank chamber is communicated through this intake passage, the shape of the cylinder becomes simpler, but a notch must be provided in the skirt of the piston to correspond to the intake port. However, this is unfavorable due to the structure of the piston.

The present invention was developed to improve these problems.The cylinder structure is simple, there is no need to provide a cutout in the skirt of the piston, and the flow path resistance of the auxiliary scavenging air flow is low. The purpose is to obtain a two-stroke internal combustion engine with improved efficiency.

The present invention will be explained below according to an embodiment shown in the drawings.

In the figure, 1 is the cylinder, 2 is the piston, 3 is the crank chamber, and 4
5 is an exhaust port, 5 is an intake port, 6 is an intake path, 7 is a reed pulp, and 8 is a vaporizer.

A pair of main scavenging air ports 9, 9 are provided in the cylinder 1, located between the exhaust port 4 and the intake port 5, and facing each other. It communicates with the crank chamber 3 via 13.

A sub-scavenging port 10 is located between these main scavenging ports 9 and 9 on the intake port 5 side.
is formed, and this sub-scavenging port 10 is opened above the intake port 5.

The sub-scavenging air port 10 is connected to the upper part of the intake passage 6 in the vicinity of the intake port 5 via a sub-scavenging passage 11 provided in the inner wall of the cylinder 1. It is approximately straight along the direction.

The lower part of the intake passage 6 near the intake port 5 and the crank chamber 3 are connected to a communication passage 12 provided inside the inner wall of the cylinder 1.
communicated by.

This communication passage 12 extends straight on the inner wall surface of the cylinder 1, communicates the crank chamber 3 and the inside of the intake passage 6 at the shortest distance, and faces the sub-scavenging passage 11 within this intake passage 6. has been done.

According to the embodiment of the present invention configured as described above, when the piston 2 descends during the scavenging stroke, the fresh air filled in the crank chamber 3 is transmitted through the scavenging passage 13 to the main scavenging port 9,
9 into the cylinder 1, and pushes out the combustion gas in the cylinder 1 to the exhaust port 4.

At the same time, the fresh air in the crank chamber 3 is transferred to the communication path 1.
2, the air intake passage 6, and the sub-scavenging air passage 11, the air is guided to the cylinder 1 side, and is ejected into the cylinder 1 from the sub-scavenging port 10 as an auxiliary scavenging air flow.

Therefore, fresh air is blown into the area between the main scavenging ports 9.9 where fresh air has a poor flow, improving the scavenging efficiency.

In this case, the sub-scavenging air passage 11 and the communication passage 12 are straight and are opposed to each other in the intake passage 6, so that the flow direction of the auxiliary scavenging air flow is approximately linear.

Therefore, the flow velocity of the auxiliary scavenging airflow and the main scavenging airflow in the main scavenging passage 13 are approximately equal, and the auxiliary scavenging airflows do not interfere with each other, resulting in a stable flow.

Moreover, since the communication passage 12 connects the inside of the intake passage 6 and the crank chamber 3 at the shortest distance, the flow path resistance of the auxiliary scavenging air flow is significantly reduced, so that the flow of the auxiliary exhaust air flow becomes linear. In combination, the air inside the cylinder 1 can be scavenged quickly, and the scavenging efficiency is significantly improved.

Furthermore, since the sub-scavenging passage 11 does not need to be provided by bypassing the intake passage 6, the cylinder 1 is symmetrical and its structure is simple.

Furthermore, since the intake passage 6 and the crank chamber 3 are in direct communication with each other through the communication passage 12, there is no need to provide a notch in the skirt portion of the piston 2, and therefore, troublesome machining of the piston 2 can be omitted. There are advantages.

The present invention described in detail above provides a sub-scavenging port located above the intake port between the main scavenging ports, communicates the sub-scavenging port and the intake passage via the sub-scavenging passage, and This is a two-stroke internal combustion engine in which the engine and the crank chamber are communicated with each other through a straight communication passage, and the communication passage and the sub-scavenge air passage are opposed to each other in the intake passage.

According to this, the flow of the sub-scavenging air flow in the sub-scavenging air passage and the communication passage becomes linear, and the communication passage connects the crank chamber and the intake passage through the shortest distance, so that the flow of the sub-scavenging air flow becomes linear. The resistance is significantly reduced, so the scavenging efficiency is greatly improved, and the air in the cylinder can be quickly scavenged.

In addition, since the sub-scavenging passage does not need to be provided around the intake passage, the cylinder becomes symmetrical and the structure can be simplified.Furthermore, the intake passage is communicated with the crank chamber via the communication passage, so the skirt of the piston There is no need to provide a notch in the piston, and there are excellent effects such as the ability to omit troublesome machining of the piston.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a longitudinal sectional view, and FIG. 2 is a sectional view taken along the line ■-■ in FIG. 1...Cylinder, 3...Crank chamber,
4...exhaust port, 5...intake port, 6...
...Intake path, 9...Main scavenging air port, 10...
... Sub-scavenging air port, 11... Sub-scavenging air passage, 12...
...Communication path.

Claims (1)

[Scope of utility model registration request] An intake port and an exhaust port are provided on the inner surface of the cylinder, and a main scavenging port connected to the crank chamber is provided between these intake ports and the exhaust port, facing each other. In a two-stroke internal combustion engine in which an auxiliary scavenging port is provided at an upper position, and the auxiliary scavenging port and an intake passage connected to the intake port are communicated via the auxiliary scavenging passage, the intake passage and the crank chamber are directly connected. A two-stroke internal combustion engine, characterized in that the two-stroke internal combustion engine communicates with the auxiliary scavenging passage within the intake passage.