JPH064038Y2 - Exhaust smoke prevention structure for 2-cycle engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an exhaust smoke prevention structure for a two-cycle engine.

[Prior Art and its Problems] Conventionally, in a 2-cylinder crank chamber compression type 2-cycle engine having a 90- or 180-degree phase crank, when the vehicle accelerates rapidly after low-speed running and idling, the exhaust gas becomes so-called white smoke. May be. This is because the engine oil accumulated in the lower portion of the crank chamber during idling excessively flows into the combustion chamber through the scavenging holes during acceleration and causes incomplete combustion.

As a means for solving such a problem, a two-cycle engine described in Japanese Utility Model Publication No. 58-7813 has been proposed. This two-cycle engine includes a pair of two-stage cylinders having a small diameter portion and a large diameter portion, each having a small diameter portion and a large diameter portion.
The second-stage piston is fitted to form an annular auxiliary suction chamber between the second-stage cylinder and the second-stage piston, and the auxiliary suction chamber of the first cylinder is connected to the second cylinder of the second cylinder having a phase difference of 180 degrees via the auxiliary intake passage. The second intake cylinder of the second cylinder communicates with the crank chamber, the scavenging passage, or both, and the second intake cylinder of the second cylinder communicates with the crank chamber of the first cylinder, the scavenging passage, or both via the auxiliary intake passage. The chamber, the crank chamber, or both are connected to the carburetor via a check valve.

In this two-cycle engine, the annular auxiliary suction chamber formed between the two-stage cylinder and the two-stage piston is used as an auxiliary pump for the adjacent cylinders having a phase difference of 180 °, so the output is improved by supercharging. In addition to the main effect of being able to expect, it is possible to prevent engine oil from collecting in the lower part of the crank chamber during idling by connecting the auxiliary suction chamber of one cylinder and the lower part of the crank chamber of the other cylinder with a passage. Therefore, it is also effective as a measure against white smoke in a two-cycle engine.

However, since the above-mentioned white smoke prevention means connects the auxiliary suction chamber of one cylinder and the lower part of the crank chamber of the other cylinder by a passage, a two-stage cylinder and a two-stage piston are required to form the auxiliary suction chamber. Therefore, the structure of the engine is complicated, and the piping is routed in the narrow part around the engine, which is very troublesome to manufacture and assemble.

Therefore, the present invention is intended to provide an exhaust smoke prevention structure in an ordinary crank chamber compression type two-cycle engine in which an oil pool does not occur in the lower portion of the two-cylinder crank chamber.

[Means for Solving the Problems] The exhaust smoke prevention structure for a two-cycle engine according to the present invention for solving the above-mentioned problems is that the lowermost part of the two-cylinder crank chamber of the two-cycle engine is connected by a small-diameter tube. It is characterized by.

[Operation] As described above, in the exhaust smoke prevention structure of the two-cycle engine of the present invention, since the lowermost part of the two-cylinder crank chamber is communicated with the thin tube, the engine oil accumulated in the lower part of the crank chamber during idling Flows into a small-diameter tube and when the piston of one cylinder descends, it blows out into a crank chamber where the pressure of the other cylinder has risen to lower the pressure and becomes a mist.When the piston of the other cylinder descends, Due to the rise of the piston of the cylinder, the mist blows out into the crank chamber where the pressure becomes low, and the mist engine oil enters the combustion chamber through the scavenging holes in the scavenging stroke and burns together with the air-fuel mixture. Therefore, the engine oil does not collect, the engine oil does not excessively flow into the combustion chamber during acceleration, and incomplete combustion does not occur, so that white smoke is not emitted from the muffler.

[Embodiment] An embodiment of an exhaust smoke prevention structure for a two-cycle engine according to the present invention will be described with reference to the drawings. In the figure, reference numerals 1 and 2 respectively denote a first cylinder and a second cylinder of a crank chamber compression type two-cycle engine, which have a phase difference of 180 degrees from each other. 1st cylinder 1
3 is crankshaft, 4 is cylinder, 5 is piston, 6
Is a piston pin, 7 is a connecting rod, 8 is a crank pin, 9 is a crank chamber, and 10 is a scavenging hole communicating with the crank chamber 9 and having an upper end opened to the cylinder 4. Reference numeral 11 is a combustion chamber, and 12 is a spark plug. The second cylinder 2 has the same structure as the first cylinder 1 except that it has a phase difference of 180 degrees with respect to the first cylinder 1, and corresponding parts are marked with "'".

The crank chambers 9 and 9'of the first cylinder 1 and the second cylinder 2
Small holes 13 and 13 'are provided at the center of the lowermost part of each of these, and L-shaped pipe joints 14 and 14' are attached to the small holes 13 and 13 'so as to face each other, and between the pipe joints 14 and 14'. A small tube 15 is attached to connect the crank chambers 9 and 9 '.

In this way, the lowermost part of the crank chamber 9 of the first cylinder 1 and the lowermost part of the crank chamber 9'of the second cylinder 2 are communicated with each other through the tube 15, the pipe joints 14 and 14 ', and the small holes 13 and 13'. Therefore, the engine oil accumulated in the lower portions of the crank chambers 9 and 9 ′ during idling flows into the tube 15 through the small holes 13 and 13 ′ and the pipe joints 14 and 14 ′, and the piston 5 of the first cylinder 1 At the time of descending, the piston 5'of the second cylinder 2 rises and is blown into the crank chamber 9 ', where the pressure is lowered, and becomes a mist.
Further, when the piston 5'of the second cylinder 2 is lowered, the crank chamber 9 whose pressure is lowered by the rise of the piston 5 of the first cylinder 1
Extract into mist. The engine oil thus misted enters the combustion chambers 11 and 11 'through the scavenging holes 10 and 10', respectively, in the scavenging stroke of the first cylinder 1 and the second cylinder 2, and burns together with the air-fuel mixture. Therefore, the engine oil is the first cylinder 1
And the lower part of the crank chambers 9 and 9'of the second cylinder 2 is no longer accumulated, and the engine oil during acceleration is stored in the combustion chambers 11 and 11 '.
Since there is no excessive inflow to the muffler and incomplete combustion does not occur, no white smoke is emitted from the muffler.

[Effects of the Invention] As can be seen from the above description, the exhaust smoke prevention structure of the two-cycle engine of the present invention communicates the lowermost part of the two-cylinder crank chamber with a small-diameter tube, so that the engine is located below the crankcase. The oil does not collect and flows into the tube,
When one piston descends, it blows out to the other crank chamber due to the pressure difference and becomes a mist.When the other piston descends, it blows out to one crank chamber due to the pressure difference and becomes a mist. It enters the combustion chamber through and burns together with the air-fuel mixture. Therefore, since the engine oil does not excessively flow into the combustion chamber during acceleration, white smoke is not emitted from the muffler, which is useful for pollution control.

Also, the exhaust smoke prevention structure of the two-cycle engine of the present invention is
Since the lowermost part of the two-cylinder crank chamber is simply connected by a small-diameter tube, the structure is simple, and the tube can be easily attached even in a narrow part around the engine, so that the production and assembly are easy.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view showing a crankcase compression type two-cycle engine having an exhaust smoke prevention structure of the present invention. 1 ... 1st cylinder, 2 ... 2nd cylinder, 3, 3 '... crankshaft, 4, 4' ... cylinder, 5, 5 '... piston, 6, 6' ... piston pin, 7, 7 '... connecting rod, 8, 8 '... crank pin, 9, 9' ... crank chamber, 10, 10 '... scavenging hole, 11, 11' ... combustion chamber, 12 ... spark plug, 13, 13 '... small hole, 14, 14' ... pipe Fitting, 15… Thin tube.

Claims (1)

[Scope of utility model registration request] 1. An exhaust smoke prevention structure for a two-cycle engine, characterized in that the lowermost part of a two-cylinder crank chamber of the two-cycle engine is connected by a small-diameter tube.