JPH0565825A - Premixed stratified air supply two cycle engine - Google Patents

Abstract

PURPOSE:To prevent a rich mixture from escaping to the outside from an exhaust port before combustion by shutting off flow of rich mixture which flow into a combustion chamber from a second scavenging port toward the exhaust port side by scavenging air stream of rich mixture which flows into the combustion chamber from a first scavenging port. CONSTITUTION:Two cylinders 2, 3 perform combustion simultaneously in an engine, and a lean mixture from a crank chamber S1 and a rich mixture from a crank chamber S2 flow into combustion chambers S3, S4 simultaneously. A first scavenging port 15 is positioned between a second scavenging port 16 and an exhaust port 17 and directed toward the cylinder head 12 side. Scavenging air stream of the lean mixture which flows into the combustion chamber S3 (S4) from the first scavenging port 15 is injected before the rich mixture which flows in from the second scavenging port 16 to prevent the rich mixture from flowing into the exhaust port 17 side. Thus, it is possible to prevent the rich mixture from escaping to the outside from exhaust port 17 before combustion and improve output power and fuel efficiency.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a premixed stratified charge two cycle engine.

[0002]

2. Description of the Related Art There is a two-cycle engine in which primary combustion is performed with a rich air-fuel mixture fed into a combustion chamber, and secondary combustion is performed with a lean air-fuel mixture fed next. Japanese Unexamined Patent Publication No. 50-121606 discloses such a two-cycle engine. In this engine, a rich air-fuel mixture is sent from an opening formed in a piston toward a combustion chamber, and combustion is performed from a scavenging port formed in a cylinder. A lean mixture is sent to the room.

[0003]

However, in such an engine, when the rich air-fuel mixture is sent into the combustion chamber, a part of it may escape from the exhaust port before combustion. In such a case, Had a problem that the output decreased and the combustion deteriorated.

[0004]

In order to solve the above-mentioned problems, the present invention is a two-cycle engine having a scavenging port and an exhaust port opening to the combustion chamber and scavenging the combustion chamber with fresh air flowing from the scavenging port. The scavenging port is composed of a first scavenging port for a lean mixture and a second scavenging port for a rich mixture, and the scavenging flow of the lean mixture flowing into the combustion chamber from the first scavenging port is used for the second scavenging flow. The feature is that the flow of the rich mixture flowing from the scavenging port into the combustion chamber to the exhaust port side is blocked.

[0005]

The function of the lean air-fuel mixture flowing from the first scavenging port into the combustion chamber blocks the flow of the rich air-fuel mixture flowing from the second port toward the exhaust port side, whereby the rich air-fuel mixture is exhausted before combustion. It is possible to prevent escape from the mouth to the outside.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a plan sectional view of a premixed stratified charge two-cycle engine, in which reference numeral 1 is a crankcase, two crank chambers S1 and S2 are formed in the crankcase 1, and the outer surface of the crankcase 1 is formed. Is provided with a pair of cylinders 2, 3. The crank chamber S1 is supplied with only a lean air-fuel mixture (or air), and the crank chamber S2 is supplied with only a rich air-fuel mixture.

A crankshaft 4 is rotatably inserted into the crank chambers S1 and S2, and a crankpin 4a provided on the crankshaft 4 and a piston 5 in the cylinder 2 are connected by a connecting rod 6 to form a crankshaft 4 Crankpin 4b provided on the piston and piston 7 in the cylinder 3
And the connecting rod 8 are connected. A cylinder head 9 is attached to the upper end of the cylinder 2, a combustion chamber S3 is formed between the cylinder head 9 and the piston 5, and the tip of an ignition plug 10 attached to the cylinder head 9 is attached to the combustion chamber S.
Show within 3. Similarly, a cylinder head 12 is attached to the upper end of the cylinder 3, a combustion chamber S4 is formed between the cylinder head 12 and the piston 7, and the cylinder head 1
The tip of the spark plug 13 attached to the No. 2 is exposed to the inside of the combustion chamber S4.

A first scavenging port 15, a second scavenging port 16 and an exhaust port 17 are formed in the cylinders 2 and 3, respectively, and the first scavenging port 15 is located between the second scavenging port 16 and the exhaust port 17. And the cylinder heads 9 and 12
Form it so that it points to the side. In the figure, reference numeral 18 is a notch formed in each of the pistons 4 and 5 and guiding the flow of the rich mixture from the second scavenging port 16. A first space is provided between the crank chamber S1 and the first scavenging port 15 of the cylinder 2.
A scavenging passage 20 is provided to communicate the crank chamber S1 with the combustion chamber S3, and similarly, a first scavenging passage 21 is provided between the crank chamber S1 and the first scavenging port 15 of the cylinder 3 to provide the crank chamber S1 with the combustion chamber. Connect S4. Further, the crank chamber S
2 and the second scavenging port 16 of the cylinder 2 are provided with a second scavenging passage 22 to communicate the crank chamber S2 and the combustion chamber S3, and similarly, the crank chamber S2 and the second scavenging port 16 of the cylinder 3 are connected. A second scavenging passage 23 is provided between them to connect the crank chamber S2 and the combustion chamber S4.

As described above, in the engine of the present embodiment, the two cylinders 2 and 3 are designed to explode together, and the lean air-fuel mixture from the crank chamber S1 and the rich air-fuel mixture from the crank chamber S2 are simultaneously burned in the combustion chamber S3. It is designed to flow into S4. That is, the lean air-fuel mixture from the crank chamber S1 flows into the combustion chambers S3 and S4 from the first scavenging ports 15 and 15 through the first scavenging passages 20 and 21, respectively, and at the same time, the rich air-fuel mixture from the rank chamber S2. Passes through the second scavenging passages 22 and 23 from the second scavenging ports 16 and 16 to the combustion chambers S3 and S4, respectively.
Flows in. By the way, in this embodiment, the first scavenging port 1
5 is located between the second scavenging port 16 and the exhaust port 17 and is directed to the cylinder heads 9 and 12 side, the first scavenging port 15 to the combustion chamber S as shown in FIG.
3 (S4), the scavenging flow of the lean air-fuel mixture is ejected from the second scavenging port 16 in front of the rich air-fuel mixture B, and blocks the rich air-fuel mixture B from flowing to the exhaust port 17 side. Therefore, according to this embodiment, the rich mixture B is discharged into the exhaust port 1 before combustion.
It is possible to prevent the vehicle from escaping to the outside, and it is possible to improve the output and the fuel consumption.

FIG. 3 shows another embodiment. In this embodiment, a second scavenging port 16 is provided between the first scavenging port 15 and the exhaust port 17, and the second scavenging port 16 is the piston 5
The second scavenging port 1 is directed toward the recess 30 formed in (7).
The rich mixture B flowing in from 6 swirls in the recess 30.
Further, the lean air-fuel mixture A flowing from the first scavenging port 15 flows to the exhaust port 17 so as to exceed the rich air-fuel mixture B, and the flow of the lean air-fuel mixture A causes the rich air-fuel mixture B to exit from the exhaust port 17. It is possible to prevent the escape.

[0011]

As described above, according to the present invention, the first
The flow of the lean air-fuel mixture from the scavenging port into the combustion chamber blocks the flow of the rich air-fuel mixture from the second port to the exhaust port, which prevents the rich air-fuel mixture from escaping from the exhaust port to the outside before combustion. can do.

[Brief description of drawings]

FIG. 1 is a plan sectional view of a two-cycle engine.

FIG. 2 is an enlarged sectional view of a main part.

FIG. 3 is a view similar to FIG. 2 according to another embodiment.

[Explanation of symbols]

 2, 3 ... Cylinder, 15 ... First scavenging port, 16 ... Second scavenging port, 17 ... Exhaust port, S3, S4 ... Combustion chamber.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinichi Isomura 1-4-1 Chuo, Wako-shi, Saitama Inside the Honda R & D Co., Ltd. (72) Inventor Osamu Kudo 1-4-1 Chuo, Wako-shi, Saitama Incorporated Honda Technical Research Institute (72) Inventor Michio Okubo 1-4-1 Chuo Wako, Saitama Incorporated Honda Technical Research Institute

Claims (2)

[Claims] 1. A two-cycle engine having a scavenging port opening to a combustion chamber and an exhaust port, and scavenging the combustion chamber with fresh air flowing from the scavenging port, wherein the scavenging port is a first scavenging port for a lean mixture. And a second scavenging port for the rich air-fuel mixture, and an exhaust port for the rich air-fuel mixture that flows into the combustion chamber from the second scavenging port with a scavenging flow of the lean air-fuel mixture that flows into the combustion chamber from the first scavenging port. A premixed stratified charge two-cycle engine characterized by blocking the flow to the side. 2. A pair of at least one pair of cylinders that are in the same explosion,
It has two crank chambers for lean and rich mixtures,
The first scavenging port and the second scavenging port are respectively formed in the cylinders, and the crank chamber for lean mixture and the first scavenging port of each cylinder are communicated with each other through a first scavenging passage and the rich mixture is formed. 2. The premixed stratified charge two-cycle engine according to claim 1, wherein a crank chamber for the engine and a second scavenging port of each cylinder communicate with each other through a second scavenging passage.