JPS63186913A - Intake device for two-cycle engine - Google Patents

Abstract

PURPOSE:To improve the lubrication performance of bearings and combustion efficiency by forming a plurality of mixed gas intake passages for introducing the mixed gas supplied from a carburetor into the inside of the engine and opening the intake passage opened port towards a pair of bearings which rotatably support a crank. CONSTITUTION:The power of an engine 18 is transmitted to rear wheels 16 through a turning moment transmission mechanism in a transmission chamber 20, and bearings 28 and 30 are arranged on the opposed side surface parts of the crankcase 22 of the engine 18, and a crankshaft 32 is rotatably supported. In the vicinity of a cylinder block 24, an intake mechanism 26 consisting of the first and second intake means 60a and 60b arranged at the right and left is arranged. The opened port parts of the pipe bodies 66a and 66b connected with the introducing ports of the carburetors 62a and 62b installed onto the intake means 60a and 60b are formed so as to be set close to the bearings 30 and 28, which are lubricated by the mixed gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a suction device for a two-stroke engine. The present invention relates to a suction device for a two-stroke engine configured to further improve the balance of action and lubrication performance.

[Prior Art] Two-stroke engines have been used in motorized bicycles, motorcycles, and the like. The two-stroke engine is widely used, particularly in small-displacement ff1 (125 cc or less) motorcycles.

Therefore, the two-stroke engine is basically configured as follows. That is, the two-stroke engine includes a carburetor and an intake device having an intake passage that introduces the air-fuel mixture supplied from the carburetor into the crankcase. A reed pulp is disposed within the intake passage to prevent the inconvenience of the fuel mixture flowing back from the crankcase side to the carburetor side. A crankshaft is rotatably supported inside the crankcase via a bearing member such as a bearing.

A cylinder block is provided at one end of the crankcase, and a piston that is slidably fitted into the cylinder block is disposed inside the cylinder block. Therefore, the cylinder block and the piston define a combustion chamber. Further, the piston is connected to the crankshaft via a connecting rod, so that when the piston reciprocates, the crankshaft rotates. Further, the cylinder block is provided with a plurality of scavenging passages for guiding the air-fuel mixture introduced into the crankcase to the combustion chamber, and an exhaust passage for discharging gas exploded within the combustion chamber.

In the two-stroke engine configured as above,
When the piston moves up, air-fuel mixture is introduced into the crankcase from the carburetor through the suction passage. Furthermore, when the piston descends, the residual gas in the combustion chamber is exhausted to the outside through the exhaust hole, and the air-fuel mixture introduced into the crankcase is supplied into the combustion chamber through the scavenging passage. be done. In this case, the air-fuel mixture supplied into the combustion chamber serves to push out the residual gas.

Incidentally, in the two-stroke engine as described above, the intake passage for introducing the air-fuel mixture into the crankcase is generally configured as a single passage. Therefore, the cross-sectional area of the suction passage cannot be increased by more than a predetermined amount.

Further, in the two-stroke engine, as described above, a so-called scavenging action is performed to exhaust gas combusted by the air-fuel mixture supplied into the combustion chamber. In this case, the amount of the air-fuel mixture that passes through each of the plurality of scavenging passages for supplying the air-fuel mixture into the combustion chamber varies depending on the distance from the suction passage to each scavenging road. Therefore, in some cases, the air-fuel mixture supplied from one scavenging road is discharged to the exhaust hole side by the air-fuel mixture supplied from the other scavenging hole.

Furthermore, if the lubricating oil mixed into the air-fuel mixture introduced into the crankcase is configured to lubricate bearing members such as bearings disposed within the crankcase, it is possible to lubricate bearing members such as bearings disposed within the crankcase. There may be cases where the lubricating oil supply is not sufficient.

[Problems to be Solved by the Invention] The present invention has been made to overcome the above-mentioned disadvantages, and includes an intake passage for introducing the air-fuel mixture from the carburetor into the crankcase of the two-stroke engine. In addition to providing a plurality of suction passages, the suction passage is configured to open toward the bearing member in the crankcase, thereby improving the lubrication performance of the bearing member and maintaining a well-balanced air-fuel mixture in the combustion chamber during scavenging. An object of the present invention is to provide an intake device for a two-stroke engine that can further improve combustion efficiency and increase the output of the engine itself.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention provides a two-stroke engine in which a crank is rotatably supported within the crankcase via a set of bearings. at least one carburetor for introducing the air-fuel mixture, a plurality of air-fuel mixture intake passages for introducing the air-fuel mixture derived from the carburetor into the engine, and a valve for controlling communication between the respective air-fuel mixture intake passages, The suction passage openings are each configured to open toward one set of bearings.

[Embodiments] Next, preferred embodiments of the two-stroke engine intake device according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a motorcycle that employs the inhalation device for a two-stroke engine according to the present invention, and the motorcycle IO basically includes a body 12, a front wheel 14,
It consists of a rear wheel 16. An engine 18 is mounted at the rear of the body 12, and a transmission compartment 20 is disposed close to the engine 18. In this case, the transmission chamber 20 is disposed on one side of the body 12, and inside thereof there is a rotational force transmission mechanism (not shown) for shifting and transmitting the rotation of the engine 18 to the rear wheels 16. provided.

As shown in FIG. 2, the engine 18 includes a crankcase 22, a cylinder block 24, a cylinder head 25 that closes the upper part of the cylinder block 24, and an intake mechanism 26.

A bearing 28 and a bearing 30 are disposed on opposing side surfaces of the crankcase 22, respectively, and a crankshaft 32 is fitted into the bearings 28 and 30. The crankshaft 32 includes weights 34a and 34b disposed substantially inside the crankcase 22;
A crank bin 36 that connects these weights 34a and 134b, a support shaft 38 that bulges outward from the weight 34a, and a support shaft 40 that projects outward from the weight 34b.
It is integrally composed of. In this case, the support shaft 38 is fitted into the bearing 28, and a generator 42 is attached to the end thereof. On the other hand, the support shaft 40 fits into the bearing 30, and its end portion is connected to the crankcase 22.
The transmission chamber 20 extends through the transmission chamber 20 . A drive pulley 44 is fitted to the tip of the support shaft 40, and a heald 46 is stretched around the drive pulley 44.

Further, one end side of a connecting rod 48 is rotatably engaged with the crank pin 36. The other end of the connecting rod 48 is engaged with a piston 50 disposed within the cylinder block 24. In this case, the piston 50 is inserted into a cylinder chamber 52 defined inside the cylinder block 24.
The piston 5 is slidably fitted into the piston 5.
It will be easily understood that the combustion chamber 54 is defined by the engine 0, the cylinder block 24, and the cylinder head 25.

Furthermore, a pair of scavenging passages 54a, 54b and an exhaust passage 55 are formed inside the cylinder block 24. The scavenging passages 54a and 54b are connected to the cylinder block 24.
Extending from one surface to the middle part of the cylinder chamber 52 defined by the cylinder block 24, and communicating between the inside of the crankcase 22 and the combustion chamber 54 when the piston 50 is located below. become. A spark plug 56 is screwed into the cylinder head 25 that closes the upper part of the cylinder block 24.
The tip faces the combustion chamber 54.

Next, a suction mechanism 26 is installed near the cylinder block 24.
to be placed. The suction mechanism 26 is connected to the cylinder block 24
In the figure, the first suction means 60 disposed on the right side
a and a second suction means 60b disposed on the left side of the cylinder block 24.

It should be noted that the first suction means 60a and the second suction means 60b are constructed approximately the same and are arranged in symmetrical positions. Therefore, the first suction means 60a will be described in detail here. Regarding the second suction means 60b, reference numerals indicating the same components as those of the first suction means 60a are given a suffix, and detailed explanation thereof will be omitted.

The first suction means 60a includes a carburetor 62a for producing a mixture as fuel, and a pipe body 66a forming an air-fuel mixture suction passage 64a is connected to an outlet port of the carburetor 62a. The opening faces the bearing 30.

A flange portion is formed at the end of the tube body 66a, and the tube body 66a is airtightly joined to the crankcase 22 via the flange portion. It will be easily understood that the air-fuel mixture generated in the carburetor 62a is thus configured to be fed into the crankcase 22 via the suction passage 64a. Therefore, a reed valve 68a is attached to the joint portion of the pipe body 66a and the crankcase 22. This reed valve 68a swings in the direction shown by the arrow in the figure to control communication of the suction passage 64a. Note that here, it goes without saying that the opening of the tubular body 66b faces the bearing 28.

The engine employing the intake mechanism according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the action when the piston 50 forming the engine 18 rises from the bottom dead center will be described.

That is, when the piston 50 rises, the suction mechanism 2
6 reed valves 68a and 68b swing to open the suction passage 6.
4a and 64b are in communication with the inside of the crankcase 22. Therefore, the air-fuel mixture led out from the carburetors 62a, 62b is transferred to the suction passages 64a, 64a, 64b of the pipe bodies 66a, 66b.
4b into the inside of the crankcase 22. In this case, the air-fuel mixture introduced into the crankcase 22 fills within the crankcase 22 and lubricates the bearings 28, 30, thereby serving to prevent burnout or the like of the bearings. Further, since a plurality of suction passages are provided, the cross-sectional area is substantially doubled, and suction efficiency can be improved.

Next, the piston 50 reaches the top dead center, and the air-fuel mixture previously filled in the combustion chamber 54 explodes under the ignition action of the spark plug 56. The piston 50 starts to descend due to the explosive force of the air-fuel mixture.

At this time, the gas exploded within the combustion chamber 54 is removed from the exhaust passage 5.
It is discharged outward from 5. On the other hand, the lead pulps 68a and 68b of the suction mechanism 26 are connected to the suction passages 64a and 64b.
Therefore, the air-fuel mixture filling the crankcase 22 enters the fuel chamber 54 via the scavenging passages 54a and 54b. The air-fuel mixture that has entered the combustion chamber 54 completely pushes out the gas remaining in the combustion chamber 54 to the outside through the exhaust passage.

Next, the piston 50 begins to rise again, compressing the air-fuel mixture filled in the combustion chamber 54, and the reed pulps 68a, 68b open again, supplying new air-fuel mixture into the crankcase 22. will be done.

By repeating the above actions, the piston 50
The crankshaft 32 reciprocates within the cylinder chamber 52 and is connected to the piston 50 via a connecting rod 48.
rotates in a predetermined direction. This rotational force is applied to drive pulley 4
4. The rotational force is transmitted to the rear wheel 16 via the belt 46 and a rotational force transmission mechanism disposed within the transmission chamber 20.

In this case, according to this embodiment, even when the piston 50 reciprocates at a considerably high speed, the carburetors 62a, 62b
from the crankcase 2 via suction passages 64a and 64b.
Since the air-fuel mixture is supplied into the combustion chamber 54, the air-fuel mixture is introduced into the combustion chamber 54 approximately evenly from both the scavenging passages 54a and 54b. As a result, scavenging of exhaust gas can be performed reliably, and combustion efficiency can be increased.

Although two carburetors are provided in this embodiment, it goes without saying that the same effect can be obtained even if the carburetors are constructed as a single carburetor and the suction passage itself is constructed with branches.

[Effects of the Invention] As described above, according to the present invention, there is provided an intake device that is attached to a two-stroke engine and supplies a mixture as fuel to a crankcase, the intake device supplying the mixture to the crankcase as fuel. A plurality of suction passages are provided so that the air-fuel mixture is introduced into the combustion chamber substantially uniformly.

Therefore, the suction efficiency of the air-fuel mixture is improved, and the scavenging effect of the air-fuel mixture can be reliably performed.

As a result, the combustion efficiency of the engine itself employing the intake device is improved and its output is increased. Furthermore, since the air-fuel mixture is evenly sucked into the crankcase, there is also the advantage that the lubricity of bearing members such as bearings disposed within the crankcase is improved.

Although the present invention has been described above by citing preferred embodiments, the present invention is not limited to these embodiments (
It goes without saying that various improvements and changes in design can be made without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a schematic explanatory view of a motorcycle employing the suction mechanism according to the present invention, and FIG. 2 is a partially omitted cross-sectional explanatory view of an engine to which the suction mechanism according to the present invention is installed.

Claims (1)

[Claims] (1) At least one carburetor for introducing a mixture as fuel in a two-stroke engine in which a crank is rotatably supported through a set of bearings in the crankcase, and a mixture drawn out from the carburetor. The engine includes a plurality of air-fuel mixture suction passages for introducing air into the engine, and a valve for controlling communication between the respective suction passages, and is configured such that the suction passage openings are respectively opened toward one set of bearings. An inhalation device for a two-stroke engine, which is characterized by: