JPS5812455B2 - How do you know what to do? - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides for metering fuel into the air flowing towards the engine cylinder before it enters the cylinder and dividing the air into two air volumes: scavenging air. and an amount of air containing the rationed fuel constituting the super-rich mixture, and supplying the scavenging air amount to the engine cylinders at a timing earlier than the start timing of supplying the super-rich mixture. stand up,
The present invention relates to a fuel metering device for a two-stroke internal combustion engine in which the intake and exhaust ports are controlled by an engine piston.

In two-stroke internal combustion engines, combustion problems become more important than in other internal combustion engines, especially when trying to obtain exhaust gas with fewer harmful components.

Modern two-stroke internal combustion engines require a minimum of 4% carbon monoxide in the exhaust gas immediately after combustion to avoid thermal damage.

By carrying out after-treatment in a hot exhaust pipe, the content of this harmful component can be reduced to 0.1%.

However, such an aftertreatment is only possible if a correspondingly high temperature occurs in the exhaust pipe, that is, only after the internal combustion engine has been warmed up.

In two-stroke internal combustion engines, a special problem arises in that the combustion strokes are very close together, so that the preparation and supply of the fuel-air mixture has to be correspondingly short.

The above-mentioned preparation and supply also means the effective mixing of fuel and air, as well as the filling of the air-fuel mixture into the engine cylinders in a flow-technologically advantageous manner. Therefore, while exhausting the fuel gas as completely as possible, it is necessary to reach the spark plug with a mixture that is as rich (over-rich) as possible and is easy to ignite. By air and scavenging air flow,
It is necessary to adequately separate the exhaust gas to be exterminated from the rich mixture that is likely to ignite.

The object of the invention is to improve a fuel metering device to meet the seemingly contradictory requirements mentioned above.

To do this, first, the exhaust gas is quickly removed by the scavenging air flowing into the engine cylinder without mixing in the engine cylinder, and then the rich mixture is guided while avoiding the supply of scavenging air to the vicinity of the spark plugs as much as possible. It is important to maintain good ignitability of the gas, and in short, the present invention aims to obtain a kind of laminar flow consisting of a scavenging layer and a gas mixture layer.

The present invention solves this problem by controlling the opening of the inlet port of the scavenging passage to the cylinder and then of the air-fuel mixture supply passage by means of an upper control edge closer to the combustion chamber during the combustion stroke of the engine piston. On the other hand, the lower control edge of the engine piston closer to the crankcase throttles the outlet port of the scavenging passage from the crank chamber while controlling the opening of the air-fuel mixture supply passage, and controls the engine piston to be fully closed at the bottom dead center. The point is that it is structured like this.

The scavenging air amount is first used to remove combustion gases, and then the scavenging air amount is used to remove combustion gas. While gradually decreasing
A rich mixture containing only about % of the total air intake can be prepared in a relatively simple manner and flow in a strong flow into the engine cylinder and in particular to the spark plug.

Furthermore, according to the present invention, by starting the supply of the scavenging air amount in advance of the supply start time of the rich mixture, it is possible to obtain a kind of mixture laminar flow that has an advantageous effect on the thermal process in the internal combustion engine. It will be done.

If the scavenging air is not throttled and shut off at the bottom dead center as in the present invention, the laminar flow will be destroyed by the scavenging air, the rich mixture will be diluted, and it will become difficult to ignite. The ignition and combustion process of the exhaust gas will be hindered, and the amount of toxic components in the exhaust gas will increase as well as the amount of fuel consumed.

In order to facilitate understanding of the present invention, first, the basic technology that is the starting point of the present invention will be explained in detail with reference to the drawings.

In the internal combustion engine shown in FIGS. 1 and 2, air is supplied to the cylinder 1 of the engine 2 from a crank chamber 3 which serves as a pre-compressor, and approximately the amount of air is supplied to the cylinder 1 through a scavenging passage 4. The remaining approximately % passes through the passage 5 and is sent into the cylinder 1 via the mixing chamber 6, where the air is mixed with fuel injected from the injection nozzle 7.

The combustion gases are led off via an exhaust pipe 8 , which has a bypass 9 for supplying the hot exhaust gases to a heating chamber 10 arranged around the mixing chamber 6 .

The flow of high-temperature exhaust gas in the heating chamber 10 is effected by a pressure gradient in the exhaust system, which pressure gradient is created by a throttle 11 in the exhaust muffler 12.

The crank chamber 3 is communicated with outside air via an intake pipe 13 and a filter 14.

In the intake pipe 13, an air amount measuring member 15 and an arbitrarily operable throttle valve 16 are arranged one after the other.
Furthermore, the air amount measuring element 15 is configured as a baffle plate and controls the fuel metering unit 17.

A valve 19 is arranged between the crank chamber 3, which is divided into two compression chambers by a partition wall 18, and the intake pipe 13.

Since a reciprocating air flow occurs in the intake pipe 13 due to the alternating suction of the two compression chambers of the crank chamber 30, this intake pipe section is designed with a relatively large volume in order to dampen the air flow.

The ports of the scavenging passage 4, the mixing chamber 6 and the exhaust pipe 8 to the cylinder 1 are controlled by an engine piston 20 which first controls the opening of the ports of the scavenging passage 4 and the exhaust pipe 8 during the combustion stroke, and Only after a further downward movement has the mixing chamber 6 been brought into communication with the engine cylinder 1.

The relatively large amount of air flow thus supplied through the scavenging passage 4 is used as a scavenging flow and forces the combustion gases into the exhaust pipe 8 by directing the air accordingly.

Then, as soon as the mixing chamber 6 is controlled to open by the engine piston 20, the rich mixture flows into the cylinder 1, and the mixture is fed in a countercurrent or a crossflow to the scavenging air.

This rich mixture is then directed into the active area of the spark plug in order to obtain the required effective ignition.

The pressure state that changes continuously in the crank chamber 3 is the mixing chamber 6.
A flutter valve 21 is arranged between the channel 5 and the mixing chamber 6, which serves as a filler valve.

In any case, the splitting of the air must in principle lead to the following operating process:

That is, the combustion stroke causes the engine piston 20 to open the port to the exhaust pipe and the port to the scavenging passage 4.

The incoming exhaust gas pushes the combustion gases into the exhaust pipe, the displacement of the combustion gas stream being assisted by the controlled opening of the air-fuel mixture channel 5.

The exhaust gases are forced out until the engine piston passes bottom dead center and closes the scavenging passage 4 again, and the rich mixture reaches the active range of the spark plug and is then ignited just before the end of the compression stroke.

The arrows shown inside the engine cylinder 1 in FIG. 1 indicate possible flow paths.

By the way, as already mentioned, when trying to obtain a kind of laminar flow consisting of a scavenging layer and a mixture layer,
In the configuration shown in the figure, while the air-fuel mixture supply passage is controlled to be open, the outlet port of the scavenging passage from the crank chamber is throttled and controlled to be fully closed at the bottom dead center of the engine piston. It has been found that due to the lack of fuel, the laminar flow of the mixture is destroyed by scavenging, the rich mixture is diluted, and the optimal ignition and combustion process is hindered.

On the other hand, in the engine schematically shown as an embodiment of the present invention in a longitudinal sectional view in FIG.
2 opens the passage 33 for supplying the mixture, while it is throttled by the lower control edge 31 of the engine piston 32.

Due to the restriction of the passage 30, the mixture of fuel and air flows in a stronger manner into the engine cylinder 35 from the passage 33 connected to the crank chamber 34, and can reach the vicinity of the spark plug without any hindrance.

In this case, since the scavenging passage 30 is narrowed as described above, the amount of scavenging air gradually decreases, so that the superrich mixture is not destroyed, and the optimum ignition and combustion process is obtained, and the The reduction in the amount of toxic components is extremely significant, and the fuel consumption is also significantly reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of a two-stroke internal combustion engine equipped with a fuel metering device, which is the starting point of the present invention. FIG. 2 is a schematic longitudinal cross-sectional view of the same internal combustion engine, and FIG. 1 is a schematic vertical cross-sectional view of an internal combustion engine according to the present invention. 1...Cylinder, 2...Engine, 3...Crank chamber, 4...
...Scavenging passage, 5m...Passage, 6...Mixing chamber, 7...Injection nozzle, 8...Exhaust pipe, 9...Bypass, 10...Heating chamber, 11...Aperture, 12...Exhaust muffler, 13 ...Intake pipe, 14...Filter, 15...-Air amount measuring member, 16
...Throttle valve, 17...Fuel metering unit, 18...
...Partition wall, 19...Valve, 20...Engine piston, 21...
...Flutter valve, 30... Passage for scavenging, 31... Lower control edge, 32... Engine piston, 33... Passage for supplying mixture, 34... Crank chamber, 35... Engine cylinder.

Claims (1)

[Claims] 1. Before the fuel flows into the engine cylinder, the fuel is metered into the air flowing towards the engine cylinder and the air is
The supply of air is divided into two amounts, that is, an amount of air for scavenging and an amount of air containing the metered fuel that forms a superrich mixture, and is supplied to the engine cylinders separately, and the supply start timing of the amount of air for scavenging is set to In a fuel metering device for a two-stroke internal combustion engine of the type in which the intake and exhaust ports are controlled by the engine piston prior to the start of supply of the air-fuel mixture, the engine piston 32, during the combustion stroke, A scavenging passage 300 to the cylinder is first provided by the upper control edge on the side.
While controlling the opening of the inlet port and then the inlet port of the air-fuel mixture supply passage 330, the lower control edge 31 of the engine piston 32 near the crank chamber is controlled to open the air-fuel mixture supply passage 33 from the crank chamber 34. A fuel dispensing device characterized in that the outlet port of the scavenging passage 30 is throttled and fully closed at the bottom dead center of the engine piston 32.