JP3279810B2 - Scavenging device in two-stroke internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-stroke internal combustion engine in which at least a pair of left and right scavenging ports and one exhaust port are opened in one cylinder of the cylinder. The present invention relates to a scavenging device in which a section is opened and closed by reciprocating motion of a piston in a cylinder.

[0002]

2. Description of the Related Art As a prior art, Japanese Patent Laid-Open Publication No. Hei 4-5429 discloses that in a two-stroke internal combustion engine, one exhaust port is opened laterally on the inner surface of a cylinder provided with a spark plug on the top while the cylinder is open. At least one scavenging port on each of the left and right portions sandwiching the exhaust port on the inner surface, so that air supplied from each scavenging port is blown toward the portion on the opposite side to the exhaust port in plan view. An open scavenging device has been proposed.

In this prior art, the main flow of supply air blown into the cylinder from each scavenging port is converted into a vertical swirl flow toward the exhaust port by grabbing a spark plug from a portion opposite to the exhaust port. By doing so, scavenging in the cylinder is achieved.

[0004]

However, in this prior art, when viewed from the side, the blowing angle from each scavenging port into the cylinder is determined by the scavenging port on the left side of the exhaust port and the scavenging port on the right side. By making the port and the port the same, the main flow of the supply air blown into the cylinder from each of the scavenging ports is extremely simple vertical flowing toward the exhaust port by grabbing the spark plug from the part opposite to the exhaust port. Since the swirl flow in the direction becomes large, not only the amount of air supply passing through to the exhaust port is large and the air supply efficiency is low, but also the residual gas left in the substantially central portion of the cylinder increases, so the scavenging efficiency is low, There was a problem that flammability was low.

An object of the present invention is to improve this problem.

[0006]

SUMMARY OF THE INVENTION In order to achieve this technical object, the present invention provides a method of manufacturing a fuel cell comprising the steps of: "opening one exhaust port sideways on the inner surface of a cylinder having a spark plug on the top, Of these, at least one scavenging port is opened at each of the left and right portions sandwiching the exhaust port, so that air supplied from each scavenging port is blown toward a portion opposite to the exhaust port in plan view. In the scavenging device, one of the scavenging ports, which is located on one side of the exhaust port, is opened obliquely upward with respect to the axis of the cylinder and opens into the cylinder. The other scavenging port, which is located on the other side of the cylinder, is opened in the cylinder at a substantially right angle to the axis of the cylinder, and is further opened to the top surface of the piston in the cylinder. The portion close to the Chi the one scavenging port, and the ridges provided. Says "configuration having an inclined surface for channeling the supply air obliquely upward from the other scavenging ports.

[0007]

[Operation] In this configuration, the main flow of the supply air blown from each scavenging port into the cylinder toward the portion opposite to the exhaust port in plan view basically ignites from the portion opposite to the exhaust port. The swirling of the plug creates a vertical swirl flow toward the exhaust port.

In this case, the supply air from one of the scavenging ports, which is located on one side of the scavenging port with the exhaust port interposed therebetween, is blown obliquely upward toward a portion opposite to the exhaust port. The supply air from the other scavenging port, which is located on the other side of the scavenging port with the exhaust port interposed therebetween, is deflected obliquely upward by an inclined surface provided at a raised portion on the top surface of the piston, and then the one scavenging gas is supplied. Since the air supplied from the port is joined with the air supplied from the scavenging port in a state where the flow of the air is not weakened, the main flow of the air supplied from each of the scavenging ports into the cylinder is basically connected to the exhaust port. From the opposite side, the spark plug is grazed and the swirl flows in the vertical direction toward the exhaust port,
A strong swirling flow that twists the swirl flow is given to the swirl flow.

That is, the main flow of the supply air blown into the cylinder from each of the scavenging ports becomes a vertical swirl flow toward the exhaust port by grazing the spark plug from a portion opposite to the exhaust port, and the swirl flows. Since the gas flows toward the exhaust port while turning significantly in the direction perpendicular to the plane containing the flow, the amount of supply air flowing straight through to the exhaust port can be significantly reduced, and the residual gas is located substantially in the center of the cylinder. It is possible to reliably reduce the occurrence of the remaining scavenging.

[0010]

Therefore, according to the present invention, the supply efficiency and the scavenging efficiency of the two-stroke internal combustion engine can be reliably improved.
This has the effect of achieving cleaner exhaust gas and reducing fuel consumption.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In the figure, reference numeral 1 denotes a cylinder block 1 having a cylinder 2 with a built-in piston 3 in a two-stroke internal combustion engine. A cylinder head 4 having a combustion chamber 5 formed in a lower surface is fastened to the upper surface of the cylinder block 1. At approximately the center of the cylinder head 4, an ignition plug 6 is screwed so that its electrode portion looks into the combustion chamber 5. A fuel injection valve 16 for injecting and supplying fuel into the cylinder 2 is mounted on the cylinder head 4.

An exhaust port 7 is provided on one side of the cylinder block 1 so as to open laterally into the cylinder 2, and the exhaust port 7 is rotated on the other side by the two-cycle internal combustion engine. An air inlet 8 is provided from a positive displacement air compressor (not shown), such as a driven Roots blower compressor or the like. The positive displacement air compressor is a two-stroke internal combustion engine, which comprises a crankcase at a lower portion of a cylinder block 1 and a piston 3 in the cylinder 2, as is well known in the art. Is also good.

The cylinder block 1 has two one-side scavenging ports 9, 1 communicating with the air supply inlet 8 at one of the left and right sides sandwiching the exhaust port 7.
0 from the two scavenging ports 9 and 10 to the cylinder 2
The air supply to the inside is provided so as to be blown toward a portion opposite to the exhaust port 7 in a plan view. Furthermore, the exhaust port 7 is provided in the cylinder block 1.
At the other side of the left and right sides sandwiching the air supply inlet 8
The two other-side scavenging ports 11 and 12 communicating with the exhaust port 7 blow air from the two other-side scavenging ports 11 and 12 into the cylinder 2 toward a portion opposite to the exhaust port 7 in plan view. Is provided.

The scavenging ports 9, 10, 1
Both scavenging ports 9 and 10 on one side of 1, 12
When viewed from the side, an appropriate angle θ1 (preferably, about θ1 = 2
0), and the two scavenging ports 11 and 12 on the other side are opened in the cylinder 2 at a right angle to the axis 2a of the cylinder 2 in a side view. It is constituted so that.

Further, a raised portion 13 is formed on the top surface of the piston 3 so that the raised portion 13 extends along the outer periphery of the piston 3 at least from the location of the two scavenging ports 9 and 10 to the location of the exhaust port 7. The protruding portion 13 is formed at a portion on the other side of the scavenging ports 11 and 12 at an appropriate angle obliquely upward from the top surface of the piston 3 toward the one side of the scavenging ports 9 and 10. An inclined surface 14 inclined by θ2 (preferably θ2 = about 20 degrees) is provided, and the inclined surface 14 causes the air supplied from the scavenging ports 11 and 12 to flow obliquely upward. I do.

A portion of the raised portion 13 facing the scavenging ports 9 and 10 on one side is provided with an inclined surface 15 substantially parallel to the inclination angle θ1 of the scavenging ports 9 and 10 on the one side. ing. The inclined surface 14 may be formed as a concave curved inclined surface instead of a linear inclined surface. In this configuration, the main flow of the supply air blown from each of the scavenging ports 9, 10, 11, 12 into the cylinder 2 toward the portion on the opposite side to the exhaust port 7 in a plan view is basically the same as FIG. As shown by the dotted arrow A, the spark plug 6 is grazed from the part opposite to the exhaust port 7 to form a vertical swirl flow toward the exhaust port 7.

In this case, each scavenging port 9, 1
The supply air from the two scavenging ports 9 and 10 located on one side of the exhaust port 7 among the exhaust ports 7, 0, 11, and 12 is directed to a portion opposite to the exhaust port 7 by an arrow B 1 in FIG. As shown in the drawing, while the air is blown obliquely upward, air is supplied from the other scavenging ports 11, 12 located on the other side of the scavenging ports 9, 10, 11, 12 with the exhaust port 7 interposed therebetween. As shown by an arrow B2 in FIG. 2, after being deflected obliquely upward by an inclined surface 14 provided on a raised portion 13 on the top surface of The main flow of the supply air blown into the cylinder 2 from each of the scavenging ports 9, 10, 11, and 12 basically flows into the exhaust port 7 because the air flows are merged in a state where the flow of the air is less likely to be weakened. Remove the spark plug 6 from the other side First, a swirl flow in the vertical direction indicated by a dotted arrow A is directed toward the exhaust port 7. However, when the swirl flow is twisted, a strong swirling flow is generated as shown by an arrow B in FIGS. 1 and 2. Will be granted.

That is, each of the scavenging ports 9, 10, 1
The main flow of the supply air blown into the cylinder 2 from the cylinders 1 and 12 becomes a vertical swirl flow toward the exhaust port 7 by grazing the spark plug 6 from a portion opposite to the exhaust port 7 and also converts the swirl flow. Since the gas flows toward the exhaust port 7 while making a large turn in a direction perpendicular to the plane including the exhaust gas, the amount of supply air flowing straight toward the exhaust port 7 can be significantly reduced, and the residual air remains substantially in the center of the cylinder 7. It is possible to reliably reduce the occurrence of gas scavenging residue.

The scavenging ports 9, 10, 11, 1 are formed by extending the raised portion 13 on the top surface of the piston 3 to the location of the exhaust port 7.
Cylinder 2 from both scavenging ports 11 and 12 on the other side
Since the supply air blown into the inside can be prevented from passing through the exhaust port 7 by the raised portion 13, the air supply efficiency and the scavenging efficiency can be further improved.

A portion of the raised portion 13 facing the scavenging ports 9 and 10 on one side is provided with an inclined surface 15 substantially parallel to the inclination angle θ1 of the scavenging ports 9 and 10 on the one side.
Is provided, the directivity of the air supply blown into the cylinder 2 from the one-side scavenging ports 9 and 10 can be increased by the inclined surface 15 and the swirling flow indicated by the arrow B can be further strengthened. Thus, the air supply efficiency and the scavenging efficiency can be further improved.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a sectional view taken along line III-III of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylinder block 2 Cylinder 3 Piston 4 Cylinder head 5 Combustion chamber 6 Spark plug 7 Exhaust port 8 Supply air inlet 9 and 10 One side scavenging port 11 and 12 The other side scavenging port 13 Raised part 14 Slope

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-4-5429 (JP, A) JP-A-59-28628 (JP, U) JP-B-60-32008 (JP, B2) JP-B-51-2 22169 (JP, Y2) Jikken Hei 3-13531 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 17/00 F02B 25/16 F02F 3/24

Claims (1)

(57) [Claims] 1. An inner surface of a cylinder having a spark plug on the top,
While one exhaust port is opened laterally, at least one scavenging port is provided on each of the left and right portions sandwiching the exhaust port on the inner surface of the cylinder, and the air supply from each scavenging port is viewed in plan. In the scavenging device, which is opened so as to blow toward a portion opposite to the exhaust port, one of the scavenging ports located on one side of the scavenging port with respect to the exhaust port, with respect to the axis of the cylinder. The other scavenging port located on the other side with the exhaust port interposed therebetween is opened at an almost right angle to the cylinder axis while being opened obliquely upward and opening into the cylinder. An inclined surface for deflecting the supply air from the other scavenging port obliquely upward at a portion of the top surface of the piston close to the one scavenging port. The ridges provided scavenging device in a two-cycle internal combustion engine according to claim was.