JPS5896125A - Two-cycle internal-combustion engine - Google Patents

Abstract

PURPOSE:To eliminate a swirl stream in an exhaust passage and to reduce the passage resistance by providing a plurality of straightening vanes near the cylinder aperture of the exhaust passage in a uni-flow type two-cycle internal-combustion engine. CONSTITUTION:A mixture of the scavenging air and exhaust air flowed into an exhaust port 5 from a scavenging port 3 through an exhaust valve 4 while being accompanied with a swirl stream becomes a stream accompanied with no swirl movement because the kinetic energy in th swirl direction is bent in the passage direction of the exhaust port 5 through straightening vanes 7.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the scavenging efficiency of a two-stroke internal combustion engine.

FIG. 1 shows a cross-sectional view of a cylinder of a conventional UNIFLO two-stroke internal combustion engine. In the figure, 01 is a piston, 02
03 is a cylinder, and 03 is a scavenging hole, which is a plurality of passages deviated from the center of the cylinder 02 and is provided at the bottom of the cylinder 02, as shown in FIG. 04 is an exhaust valve, which is provided at the top of the cylinder 02 and approximately on the central axis of the cylinder 02. An exhaust port 05 is an exhaust passage connected to the cylinder 02 via an exhaust valve 04, and the other end is connected to an exhaust pipe (not shown). Reference numeral 06 denotes a fuel injection valve, which is provided in the upper part of the cylinder 02 at a position offset from the center axis of the cylinder 02.

During the scavenging stroke of the engine, the piston 01 is positioned near the bottom dead center and the scavenging air hole 03 is open, and scavenging air flows into the cylinder 02 through the scavenging air hole 03. At the same time, the exhaust valve 04 is opened, and the exhaust gas remaining in the cylinder 02 is mixed with the scavenging air flow and flows out through the exhaust valve 04 to the exhaust port 05 together with a part of the scavenging air.

The swirl generated in the cylinder 02 persists during the compression stroke, and good mixing with the fuel injected from the fuel injection valve 06 can be obtained, allowing the engine to perform good combustion.

However, the above method has the following drawbacks.

(1) When the scavenging air and exhaust gas that generated a swirl during the scavenging and exhausting stroke of the engine flow out to the exhaust port 05 through the exhaust valve 04, a strong vortex remains in the exhaust port 05 due to the swirl in the cylinder 02. Then, I was guided into the exhaust pipe while drawing a spiral streamline.

(2) For this reason, the flow path resistance inside the exhaust port 05 is large, and this becomes a major obstacle to flowing as much scavenging air as possible due to the differential pressure between the scavenging pressure and the exhaust pressure during the limited scavenging period. ing.

The object of the present invention is to reduce the flow path resistance caused by the vortex flow at the exhaust port of a two-stroke internal combustion engine with a uniflow set having an exhaust valve, paying attention to the above points.

The purpose of the present invention is to provide a flow rectifier that can perform scavenging well, and its features include a scavenging hole that generates a swirl in the cylinder, a scavenging valve at the top of the cylinder, and an exhaust valve that opens and closes. In a two-stroke internal combustion engine having an exhaust passage, a rectifying device made of a plurality of plates for rectifying gas flowing into the exhaust passage is provided near the opening of the exhaust passage to the cylinder.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a sectional view of a cylinder equipped with an embodiment of the device according to the invention.

In the figure, 1 is a piston, 2 is a cylinder, 3 is a scavenging hole, 4 is an exhaust valve, 5 is an exhaust port, and 6 is a fuel injection valve. These correspond to the members 01 to 06 in FIG. 2, respectively.

Reference numeral 7 denotes a flow rectifier, which is located near the opening of the exhaust port 5 to the cylinder 2 and is constituted by a plurality of plate-shaped structures provided in a radial direction from the center of the flow path of the exhaust port 5. FIG. 4 shows a cross-sectional view developed in the circumferential direction of the flow path.

The upstream side of the flow path is bent in a direction opposite to the in-cylinder swirl direction S (direction toward the swirl), and the downstream side is oriented in a direction substantially parallel to the flow path.

The plate-like structure is fixed to the wall of the exhaust port 5,
It may be fixed to the exhaust valve 4 as shown in FIG.

Note that there may be a plurality of exhaust valves.

The functions and effects of the above configuration will be described.

Exhaust from cylinder 2 through exhaust valve 4 with swirling flow? - The mixed flow of scavenging air and exhaust gas that has flowed into the exhaust port 5 tries to maintain a swirling flow inside the exhaust port 5, but the kinetic energy in the swirling direction is immediately bent by the rectifier 7 toward the flow path direction of the exhaust port 5. Thereafter, it becomes a small flow accompanied by a swirling motion and is guided to the exhaust pipe.

The above case has the following effects.

Since the swirling flow inside the exhaust port 5 is eliminated, the flow path resistance for scavenging and exhausting is reduced, and the scavenging flow rate can be increased and good scavenging can be performed without increasing the opening time area of the scavenging holes and exhaust holes.

This increases the amount of fresh air acquired in cylinder 2,
This allows for good combustion.

It is possible to achieve low fuel consumption of the engine.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing a cylinder of a conventional uniflow two-stroke internal combustion engine, Fig. 2 is a cross-sectional view taken along the ■-■ arrow in Fig. 1, and Fig. 3 is a cross-sectional view showing a cylinder of an embodiment according to the present invention. 4 is a cross-sectional view of the rectifying device shown in FIG. 3 developed in the circumferential direction of the flow path, and FIG. 5 is an explanatory diagram showing another embodiment of the rectifying device according to the present invention. , 2... cylinder, 3... scavenging hole, 4... exhaust valve, 5... exhaust port, 6... fuel injection valve, 7... rectifier. 2nd t21 1 3rd closure - 4th

Claims (1)

[Claims] (2) In a two-stroke internal combustion engine that has a scavenging hole that generates a swirl in the cylinder, an exhaust valve at the top of the cylinder, and an exhaust passage that opens and closes when the exhaust valve opens and closes, the same A two-stroke internal combustion engine characterized in that a rectifying device made of a plurality of plates is provided to rectify gas flowing into an exhaust passage.