JPH018659Y2 - - Google Patents

Description

[Detailed description of the invention] This invention is a two-stroke engine, in particular, in order to prevent the fuel mixture from blowing through, air that does not contain fuel is added to the fuel mixture sent out from the crank chamber at the beginning of the scavenging stroke. This relates to a system in which air is first supplied into the cylinder from a scavenging port.

A two-stroke engine with such a mechanism is, for example,
As disclosed in Utility Model Publication No. 55-4518,
An outside air introduction passage is connected in the middle of the scavenging air passage that connects the air-fuel mixture outlet opening into the crank chamber and the scavenging air opening opening into the cylinder. It has a structure that includes a valve.

However, in conventional systems, the air-fuel mixture outlet opens at the top of the crank chamber, so the scavenging path is relatively short, and the amount of air sent to the cylinders prior to the fuel mixture is small, so there is still a large amount of air. The reality is that the atrium is occurring.

In view of these circumstances, the purpose of the present invention is to provide a two-stroke engine with low blow-through, low fuel waste, and high thermal efficiency. The reason is that the outlet is opened and the length of the scavenging path from the air-fuel mixture outlet to the scavenging port is increased.

Hereinafter, the present invention will be explained in more detail based on the drawings.

1 and 2 show a water-cooled two-stroke gas fuel engine according to the present invention, in which a mixture outlet 2 is opened at the bottom of a crank chamber 1, and a pair of front and rear openings are provided at the peripheral wall of a cylinder 3. The scavenging port 4 is opened, and the air-fuel mixture outlet 2 and the scavenging port 4 are connected by a scavenging path 7 extending through the walls of the crankcase 5 and cylinder block 6.

The scavenging passage 7 consists of an air-fuel mixture delivery port side portion 11 and a scavenging port side portion 12 that extend from the bottom wall 8 of the crankcase 5 to the joint facing surface 10 with the cylinder block 6 via the side wall 9 around the rotational part of the crank. , the scavenging port side portion 12 is connected to the joint facing surface 10 of the crankcase 5.
The connecting groove 13 extends forward and backward in a semicircular arc shape, and the front and rear passages 14 connect the front and rear ends of the connecting groove 13 to the front and rear scavenging ports 4, respectively.

An outside air introduction passage 15 is connected to a scavenging port-side portion 12 of the scavenging passage 7 . It is desirable that the outside air introduction passage 15 is connected to the scavenging passage 7 at a location as close to the scavenging port 4 as possible, and in this example, the outside air introduction passage 15 is connected to the portions of the front and rear passages 14 closer to the scavenging port.

Reference numeral 16 denotes a check valve interposed in the outside air introduction path 15, which only allows outside air to flow into the scavenging path 7.

With the above configuration, the negative pressure generated in the crank chamber 2 during the compression stroke causes atmospheric air to flow into the outside air introduction path 15.
In the next scavenging process, a large amount of air that does not contain fuel in the scavenging channel 7 is sent into the cylinder 3 from the scavenging port 4, and after blowing away the burned waste gas. , a fuel mixture gas cylinder 3 sent from the crank chamber 2 via the scavenging passage 7
It will be squirted inside.

As described above, the present invention has the air-fuel mixture outlet opening at the bottom of the crank chamber, and the scavenging path that connects the air-fuel mixture outlet and the scavenging port, in particular, the connection point of the outside air inlet path of the scavenging path to the outside air inlet path. The connection point is located near the scavenging port and is longer than the conventional one, which opens the air-fuel mixture outlet at the top of the crank chamber. Air can be injected into the cylinder from the scavenging port, and the gas (combusted waste gas) in the so-called quenching zone is swept away with the above large amount of air before the fuel mixture is injected into the cylinder. can be kept to a very small amount,
In addition to almost eliminating raw gas emissions, wasteful use of fuel can be reduced, and thermal efficiency can be increased by, for example, 2 to 3%. In particular, this effect becomes more pronounced when the scavenging passage is run along the side wall around the rotating crank.

In addition, the present invention has a scavenging air passage that runs from the bottom wall of the crankcase through the side wall around the rotating crank to the air-fuel mixture outlet near the joint facing surface with the cylinder block, and also in the half-way between the bottom wall of the crankcase and the joint facing surface of the crankcase. It consists of a connecting groove that extends forward and backward in an arc shape, and front and rear passages that connect the front and rear ends of the connecting groove and the front and rear scavenging ports, respectively. Since the vicinity of the scavenging port in the section is communicated with the atmosphere, one side of the mixture passes through a long scavenging path and there is ventilation resistance, while the other air flows into the scavenging path near the scavenging port, resulting in a balance between the mixture and air. Good.

Incidentally, when connecting a catalytic exhaust purification device to the exhaust port, since the scavenged exhaust gas contains a large amount of air, there is no need to supply secondary air to the catalytic exhaust purification device, and the exhaust system It also has the advantage of simplifying the structure.

The present invention does not have two systems of scavenging passages: a main scavenging passage that supplies a mixture of fuel and air for scavenging, and a sub-scavenging passage that supplies only air;
It has an extremely simple configuration that simply has a single scavenging air passage, and can suppress fuel blow-through.

[Brief explanation of the drawing]

1 and 2 show an example of a water-cooled two-stroke gas fuel engine according to the present invention, with FIG. 1 being a longitudinal sectional front view and FIG. 2 being a longitudinal sectional side view. 1...Crank chamber, 2...Mixture air outlet, 3...
...Cylinder, 4...Scavenging port, 5...Crankcase, 6...Cylinder block, 7...Scavenging path, 8
. . . Bottom wall of the crankcase, 9 . Connection groove, 14... Passage, 15...
...Outside air introduction path, 16...Check valve.

Claims (1)

[Scope of utility model registration request] A mixture air outlet 2 is opened at the bottom of the crank chamber 1, while a scavenging port 4 is opened at the circumferential wall of the cylinder 3. 6
The part 1 near the air-fuel mixture outlet that reaches the opposing surface 10 connected to the
1, and a connecting groove 13 extending back and forth in a semicircular arc shape on the joint facing surface 10 of the crankcase 5.
A scavenging passage 7 is formed of front and rear passages 14 connecting the front and rear ends of the scavenging passage 7 and the front and rear scavenging openings 4, respectively. The vicinity of the scavenging port 4 of the opening portion 12 is connected to the atmosphere via an outside air introduction path 15, and a check valve 16 is interposed in the outside air introduction path 15 to allow outside air to flow from the atmosphere into the scavenging path 7. A 2-stroke engine with the following features.