JP3932267B2 - 2-cycle engine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a two-cycle engine .
[0002]
[Prior art]
A vehicle such as a motorcycle is equipped with a two-cycle engine, and the two-cycle engine is provided with an exhaust device. As this exhaust system, for example, there is an exhaust system in which an exhaust pipe is connected to an exhaust passage of a cylinder body and the exhaust pipe is provided with a muffler.
[0003]
[Problems to be solved by the invention]
In such a two-cycle engine, the air-fuel mixture compressed in the combustion chamber explodes, the piston is pushed down, the cylinder side exhaust opening of the exhaust passage opens when the piston descends, exhaust gas is discharged, and scavenging occurs when the piston descends. The cylinder side scavenging opening of the passage opens, and the air-fuel mixture in the crank chamber compressed by the lowering of the piston from this cylinder side scavenging opening is scavenged into the combustion chamber, and the exhaust gas in the combustion chamber is expelled from the cylinder side exhaust opening. Since a part of the air-fuel mixture is also exhausted, the combustion efficiency is lowered, and HC (hydrocarbon) and NOx (nitrogen oxide) in the exhaust gas are increased.
[0004]
The present invention has been made in view of such circumstances, and provides a two-cycle engine capable of improving combustion efficiency and reducing HC (hydrocarbon) and NOx (nitrogen oxide) in exhaust gas. It is intended to provide.
[0005]
[Means for Solving the Problems]
In order to solve the above-described problems and achieve the object, the present invention is configured as follows.
[0006]
According to the first aspect of the present invention, a combustion chamber is formed by a cylinder of a cylinder body, a piston provided in the cylinder, and a cylinder head mounted on the cylinder body, and an exhaust pipe is provided in an exhaust passage of the cylinder body. In a two-cycle engine provided with a muffler in the exhaust pipe,
The exhaust passage is partitioned in the cylinder axial direction to form second and first independent exhaust passages in order from the cylinder head side ,
The exhaust pipe includes an independent exhaust pipe passage communicating with the second and first independent exhaust passages;
A control unit is provided that extends in a cylinder head direction along a cylinder inner wall from a part of the head of the piston, and controls the opening and closing of the cylinder side exhaust openings of the second and first independent exhaust passages by reciprocation of the piston.
Wherein the control unit, the second and the first opening of the cylinder-side exhaust opening of the independent exhaust passages control aperture for communicating the second and the first independent exhaust passage and the combustion chamber is formed,
The control opening starts to open the cylinder side exhaust opening of the second independent exhaust passage when the piston descends, and the cylinder side exhaust opening of the first independent exhaust passage closes,
In the two-cycle engine, the cylinder-side exhaust opening of the second independent exhaust passage and the cylinder-side exhaust opening of the first independent exhaust passage are opened when the piston descends. .
[0007]
According to the first aspect of the present invention, when the air-fuel mixture in the crank chamber compressed by the lowering of the piston is scavenged into the combustion chamber, the exhaust gas in the combustion chamber is formed in the head of the piston . It is expelled from the cylinder side exhaust opening opened by the control opening , reducing the exhaust of the air-fuel mixture together with the exhaust gas, improving the combustion efficiency, and also HC (hydrocarbon) and NOx (nitrogen) in the exhaust gas Oxide) can be reduced.
[0008]
The invention according to claim 2 is characterized in that the cylinder side exhaust opening of the at least one independent exhaust passage is located on the piston top dead center side with respect to the cylinder side scavenging opening of the scavenging passage. It is a two-cycle engine .
[0009]
According to the second aspect of the present invention, the exhaust gas in the combustion chamber extends from the cylinder side exhaust opening located on the piston top dead center side to the cylinder side scavenging opening to the control opening of the control unit formed in the head of the piston. Therefore, it is reduced that the air-fuel mixture is expelled from the opened cylinder side exhaust opening and the air-fuel mixture is exhausted together with the exhaust gas.
[0010]
The invention according to claim 3 is the two-cycle engine according to claim 1, characterized in that the downstream side of the independent exhaust passage of the exhaust pipe joins at the front stage of the muffler.
[0011]
According to the third aspect of the invention, the exhaust sound is silenced by joining the downstream side of the independent exhaust passage of the exhaust pipe at the front stage of the muffler.
[0012]
According to a fourth aspect of the present invention, a relief recess of the control unit is formed on the inner wall of the cylinder head,
The ignition plug is attached to the cylinder head so as to face the combustion chamber, and the auxiliary spark plug is attached so as to face the escape recess. It is a two-cycle engine.
[0013]
According to the fourth aspect of the present invention, the ignition plug is attached to the cylinder head so as to face the combustion chamber, and the auxiliary spark plug is attached so as to face the escape recess, so that the escape recess provided on the exhaust side is provided. Combustion efficiency can be improved.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of an exhaust device for a two-cycle engine according to the present invention will be described below with reference to the drawings. 1 is a longitudinal sectional view of a two-cycle engine equipped with an exhaust device, FIG. 2 is a sectional view taken along line II-II in FIG. 1, FIG. 3 is a diagram showing control of a cylinder side exhaust opening, and FIG. 4 is an exhaust pipe and muffler FIG. 5 is a timing diagram of opening and closing of a plurality of independent exhaust passages.
[0015]
The two-cycle engine 1 includes a crankcase 2. A cylinder body 3 is placed on the crankcase 2, and a cylinder head 4 is placed on the cylinder body 3. A crankshaft 5 is rotatably supported on the crankcase 2, and a crankcase 6 is formed by the crankcase 2 and the cylinder body 3.
[0016]
A piston 8 is provided in the cylinder 7 of the cylinder body 3 so as to be able to reciprocate, and a piston ring 80 is provided on the piston 8. The small end portion of the connecting rod 9 is connected to the piston pin 81 of the piston 8, the small end portion of the connecting rod 9 is connected to the crank pin 50 of the crankshaft 5, and the piston 8 is connected to the crankshaft via the connecting rod 9. 5 is connected. By this connecting rod 9, the reciprocating motion of the piston 8 is converted into a rotational motion and transmitted to the crankshaft 5.
[0017]
A combustion chamber 10 is formed between the cylinder 7 of the cylinder body 3, the head of the piston 8, and the cylinder head 4, and a spark plug 11 is attached to the cylinder head 4 so as to face the combustion chamber 10.
[0018]
An intake passage 12 is formed in the cylinder body 3 so as to communicate with the crank chamber 6, and a reed valve 13 is attached to the intake passage 12 via a carburetor 14. The reed valve 13 is opened in an intake stroke in which the crank chamber 6 becomes negative pressure, and fuel is mixed with air by the carburetor 14, and this mixture is sucked from the intake passage 12. Thus, the reed valve 13 allows only the flow of intake air from the intake passage 12 toward the crank chamber 6, and uses the crank chamber 6 as a primary compression chamber for intake air.
[0019]
In the cylinder body 3, four main scavenging passages 15 communicating with the crank chamber 6 and the combustion chamber 10 are formed in the scavenging stroke, and sub scavenging passages 16 communicating with the intake passage 12 and the combustion chamber 10 are formed. Has been.
[0020]
The cylinder body 3 is formed with an exhaust passage 17 for discharging exhaust gas from the combustion chamber 10 during the exhaust stroke. The exhaust passage 17 includes a plurality of independent exhaust passages 17a and 17b partitioned by a partition wall 100 in the cylinder axial direction.
[0021]
An exhaust pipe 18 is connected to the exhaust passage 17 of the cylinder body 3, and a muffler 19 is provided in the exhaust pipe 18. The exhaust pipe 18 includes independent exhaust pipe passages 18a and 18b communicating with a plurality of independent exhaust passages 17a and 17b.
[0022]
The downstream sides of the independent exhaust passages 18 a and 18 b of the exhaust pipe 18 merge at the front stage of the muffler 19, and the exhaust sound is silenced by the muffler 19.
[0023]
The head 8a of the piston 8 is provided with a control portion 8b, and a control opening 8c is formed in the control portion 8b. A relief recess 4 a is formed in the inner wall of the cylinder head 4 at a position corresponding to the control portion 8 b of the piston 8.
[0024]
The reciprocating motion of the piston 8 causes the control unit 8b to open and close the cylinder side exhaust openings 17a1 and 17b1 of the plurality of independent exhaust passages 17a and 17b. The cylinder side exhaust opening 17a1 of the independent exhaust passage 17a is located closer to the piston top dead center side than the cylinder side scavenging opening 15a of the main scavenging passage 15 and the cylinder side scavenging opening 16a of the sub scavenging passage 16.
[0025]
In the two-cycle engine of this embodiment, as shown in FIG. 5, when the piston 8 is located at the top dead center TDC, the control portion 8b of the piston 8 is located in the escape recess 4a. And combustion mixture compressed in the combustion chamber 10 in this state to explode by ignition of spark plug 11, as shown in FIG. 5 pushes down the piston 8 in the descent of the piston 8, the control opening 8c of the control unit 8b Begins to open the cylinder side exhaust opening 17a1 of the second independent exhaust passage 17a and exhaust gas is discharged.
[0026]
Further, when the piston 8 descends, the cylinder-side scavenging opening 15a of the main scavenging passage 15 and the cylinder-side scavenging opening 16a of the sub-scavenging passage 16 open, and the crank chamber 6 compressed by the piston descending from the cylinder-side scavenging openings 15a, 16a. The air-fuel mixture is scavenged into the combustion chamber 10 and the exhaust gas in the combustion chamber 10 is expelled from the cylinder-side exhaust opening 17a1. At this time, the controller 8b opens the cylinder-side exhaust opening 17b1 of the first independent exhaust passage 17b. Since it is closed, a part of the air-fuel mixture is prevented from being exhausted together.
[0027]
When the air-fuel mixture in the crank chamber 6 compressed by the lowering of the piston 8 is further scavenged into the combustion chamber 10, the control opening 8c of the control unit 8b becomes the cylinder side exhaust opening 17a1, of the independent exhaust passages 17a, 17b. 17b1 is opened, the exhaust gas in the combustion chamber 10 is expelled from the cylinder side exhaust openings 17a1, 17b1, and the mixture is reduced from being exhausted together with the exhaust gas, the combustion efficiency is improved, and the exhaust gas in the exhaust gas HC (hydrocarbon) and NOx (nitrogen oxide) can be reduced.
[0028]
FIG. 6 is a longitudinal sectional view of another embodiment of a two-cycle engine provided with an exhaust device. In this embodiment, the auxiliary spark plug 110 is attached so as to face the escape recess 4a formed on the inner wall of the cylinder head 4, and the combustion efficiency in the escape recess 4a provided on the exhaust side by the auxiliary spark plug 110 is improved. Yes.
[0029]
【The invention's effect】
As described above, in the first aspect of the invention, when the air-fuel mixture in the crank chamber compressed by the lowering of the piston is scavenged into the combustion chamber, the exhaust gas in the combustion chamber is formed at the piston head. It is expelled from the cylinder side exhaust opening opened by the control opening of the part , and it is reduced that the air-fuel mixture is exhausted together with the exhaust gas, the combustion efficiency is improved, and HC (hydrocarbon) and NOx in the exhaust gas are improved. (Nitrogen oxide) can be reduced.
[0030]
In the invention according to claim 2, thus opened control opening of the control unit the exhaust gas in the combustion chamber from the cylinder-side exhaust opening formed on the head of the piston located in the piston top dead center side of the cylinder side scavenging opening As a result, the air-fuel mixture is expelled from the cylinder-side exhaust opening and the air-fuel mixture is reduced from being exhausted together with the exhaust gas.
[0031]
In the invention according to claim 3, the exhaust sound is silenced by joining the downstream side of the independent exhaust passage of the exhaust pipe at the front stage of the muffler.
[0032]
In the invention described in claim 4, the ignition plug is attached to the cylinder head so as to face the combustion chamber, and the auxiliary spark plug is attached so as to face the escape recess, thereby improving the combustion efficiency in the escape recess provided on the exhaust side. Can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a two-cycle engine equipped with an exhaust device.
2 is a cross-sectional view taken along line II-II in FIG.
FIG. 3 is a diagram illustrating control of a cylinder side exhaust opening.
FIG. 4 is a perspective view showing an exhaust pipe and a muffler.
FIG. 5 is a timing diagram of opening and closing of a plurality of independent exhaust passages.
FIG. 6 is a longitudinal sectional view of another embodiment of a two-cycle engine including an exhaust device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 2 cycle engine 3 Cylinder main body 8 Piston 8a Piston 8 head 8b Control part 17 Exhaust passage 17a, 17b Independent exhaust passage 18 Exhaust pipe 18a, 18b Independent exhaust pipe passage 19 Muffler

Claims (4)

A cylinder of the cylinder body, a piston provided in the cylinder, and a cylinder head mounted on the cylinder body form a combustion chamber, an exhaust pipe is connected to the exhaust passage of the cylinder body, and a muffler is connected to the exhaust pipe. In a two-cycle engine comprising
The exhaust passage is partitioned in the cylinder axial direction to form second and first independent exhaust passages in order from the cylinder head side ,
The exhaust pipe includes an independent exhaust pipe passage communicating with the second and first independent exhaust passages;
A control unit is provided that extends in a cylinder head direction along a cylinder inner wall from a part of the head of the piston, and controls the opening and closing of the cylinder side exhaust openings of the second and first independent exhaust passages by reciprocation of the piston.
Wherein the control unit, the second and the first opening of the cylinder-side exhaust opening of the independent exhaust passages control aperture for communicating the second and the first independent exhaust passage and the combustion chamber is formed,
The control opening starts to open the cylinder side exhaust opening of the second independent exhaust passage when the piston descends, and the cylinder side exhaust opening of the first independent exhaust passage closes,
Further, the two-cycle engine is configured to open the cylinder side exhaust opening of the second independent exhaust passage and the cylinder side exhaust opening of the first independent exhaust passage when the piston descends.   2. The two-cycle engine according to claim 1, wherein a cylinder side exhaust opening of the at least one independent exhaust passage is located closer to a piston top dead center than a cylinder side scavenging opening of the scavenging passage.   2. The two-cycle engine according to claim 1, wherein a downstream side of the independent exhaust passage of the exhaust pipe joins at a front stage of the muffler. Forming an escape recess of the control unit on the inner wall of the cylinder head;
The ignition plug is attached to the cylinder head so as to face the combustion chamber, and the auxiliary spark plug is attached so as to face the escape recess. 2-cycle engine.

Images