JPS63189615A - Scavenging device for two stroke cycle engine - Google Patents

Abstract

PURPOSE:To intend to improve scavenging efficiency regardless of engine speed by providing scavenging angle adjusting elastic members, that deform elastically in relation to colliding force with mixture, arranged in scavenging passages near scavenging ports. CONSTITUTION:Scavenging angle adjusting elastic members 46, that deform elastically in relation to colliding force with mixture, are provided arranged in scavenging passages 30 near scavenging ports 28. The same acts to make mixture keep away from an exhaust port 26 as colliding force lowers. Thereby, with no relation to engine speed, it can be does to make mixture flow suitable for improving scavenging efficiency.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a scavenging device for a two-cycle engine, and more particularly, to a two-cycle engine that can improve the inflow state of mixed gas from a scavenging port into a combustion chamber. This invention relates to an engine scavenging device.

[Conventional technology]

After schematically explaining the entire two-cycle engine in FIG. 6, the structure of a conventional scavenging device for the two-cycle engine will be explained in FIG.

In FIG. 6, a cylinder 10 has a combustion chamber 12 therein, and one spark plug 13 is mounted on the top of the cylinder 10, with its discharge gap facing into the combustion chamber 12. The piston 14 defines a lower portion of the combustion chamber 12 and slides within the cylinder 10 . The crankcase 16 is joined to the lower end of the cylinder 10, and the crankshaft 18 has an axial center portion disposed within the crankcase 16, and both ends thereof rotatably connected to the crankcase via ball bearings 20a and 20b. It is pivotally supported by 16. The connecting rod 22 is rotatably connected to the piston 14 and the crankshaft 18 through pins at the upper and lower ends, respectively, and the seals 24a and 24b are fitted to the outside of the ball bearings 20a and 20b, respectively, in the axial direction of the crankshaft 18. The inside of the crankcase 16 is kept airtight. An exhaust port 26 and a pair of scavenging ports 28 are formed below the exhaust port 26 in the side wall of the cylinder 10 that partitions the combustion chamber 12 in the radial direction. Scavenging passage 3
o is formed in the cylinder 10 and the crankcase 16,
The downstream end communicates with the scavenging port 28 and guides the mixed gas to the scavenging port 28 .

FIG. 7 is a cross-sectional view of the conventional cylinder 10 at a level including the exhaust port 26 and the scavenging port 28. 4i! Air passage 30
is formed obliquely with respect to the exhaust port 26 in the vicinity of the scavenging port 28 so as to face the wall surface portion of the combustion chamber 12 facing the exhaust port 26, and the side wall 32 on the outer corner side farther from the exhaust port 26 and a closer inner corner side wall 34 near the scavenging port 28. The outer corner side extension surface 36 is connected to both scavenging passages 30.
The inner corner side extension surface 38 is a plane extending from the outer corner side wall 32 in both the scavenging passages 30.
The intersection angle of the two outer angle side extension surfaces 36, which are planes extending from 0, is the scavenging angle θ, and the intersection line of the two outer angle side extension surfaces 36 is C1. C1
is located near the wall surface of the combustion chamber 12 on the opposite side of the exhaust port 26 with respect to the center of the combustion chamber 12, and is located a little further into the combustion chamber 12 than that point. Scavenging passage 30
The mixed gas led from the crankcase 16 via
In the scavenging passage 30 near the scavenging port 28, the outer corner side wall 3
2 and the inner corner side wall 34, and when flowing into the combustion chamber 12 from the scavenging port 28, the inflow angle is adjusted by the outer corner side wall 32 and the inner corner side wall 34. In order for the mixed gas flowing into the combustion chamber 12 from the scavenging port 28 to have an appropriate scavenging effect, the mixed gas must reach the vicinity of C1, as shown by the arrows in FIG. until the end of the exhaust port 26.
It is preferable to bend towards.

[Problem that the invention seeks to solve]

Figures 8(a) and 8(b) show the combustion chamber 12 during high speed rotation and low speed rotation, respectively, in a conventional two-cycle engine.
The figure shows the flow of mixed gas inside.

When the two-cycle engine rotates at high speed (FIG. 8(a)), the mixed gas pressure in the crankcase 16 is high.

and the inflow amount of the mixed gas from the scavenging port 28 to the combustion chamber 12 (
(in terms of weight), the mixed gas has a strong tendency to follow the outer corner side wall 32 and the inner corner side wall 34. Therefore, the mixed gas is vigorously blown out into the combustion chamber 12 from the scavenging port 28 and flows in the range between the outer corner side extension surface 36 and the inner corner side extension surface 38 up to the vicinity of C1, and forms a preferable loop trajectory in the vicinity of C1. 40, and the gas after combustion in the combustion chamber 12 can be effectively expelled from the exhaust port 26.

On the other hand, when the two-cycle engine rotates at low speed (Fig. 8(b)), the mixed gas pressure in the crankcase 16 is low, and the amount of mixed gas flowing into the combustion chamber 12 from the scavenging port 28 (weight equivalent) is low. ) is small, so the mixed gas flows to the outer corner side wall 3.
2 and the inner corner side wall 34 become weaker. Therefore, the actual inflow range 41 of the mixed gas flowing into the combustion chamber 12 from the scavenging port 28 is between the outer corner side extension surface 36 and the inner corner side extension surface 38.
As a result, the scavenging effect of the gas after combustion in the combustion chamber 12 decreases, and the mixed gas from the scavenging port 28 does not remain in the combustion chamber 12 during the scavenging stroke but exits from the exhaust port 26. this is,
This causes a decrease in the output of the two-cycle engine and an increase in fuel consumption.

An object of the present invention is to provide a scavenging device for a two-cycle engine that can obtain appropriate scavenging effects and charging efficiency regardless of the rotational speed of the two-cycle engine.

[Means for solving problems]

According to the scavenging device for a two-cycle engine of the present invention, the scavenging port and the exhaust port open into the combustion chamber, and the mixed gas is introduced into the combustion chamber from the scavenging passage through the scavenging port. A scavenging angle adjusting elastic member that elastically deforms in relation to the collision force with the mixed gas and directs the mixed gas away from the exhaust port as the collision force decreases is located in the scavenging passage near the scavenging port. It is located inside.

[Effect]

When a two-cycle engine rotates at low speed, the mixed gas pressure in the scavenging passage is low and the amount of mixed gas introduced into the combustion chamber is small. Since the angle adjusting elastic member hardly deforms, the mixed gas is directed away from the scavenging port and introduced into the combustion chamber by the scavenging angle adjusting elastic member.

However, the force of the mixed gas blowing out from the scavenging port is weak, so the mixed gas tends to bend toward the exhaust port, and this tendency and the direction provided by the scavenging angle adjusting elastic member cancel each other out. The flow of the mixed gas from the scavenging port in the combustion chamber becomes appropriate.

When a two-cycle engine rotates at high speed, the mixed gas pressure in the scavenging passage is high and the amount of mixed gas introduced into the combustion chamber is large. Therefore, the collision force of the mixed gas against the scavenging angle adjusting elastic member increases. The scavenging angle adjusting elastic member deforms significantly as the collision force increases. As a result, the scavenging angle adjusting elastic member does not direct the mixed gas that collides with it far from the exhaust port during low speed rotation of the two-cycle engine. However, the force of the mixed gas blowing out from the scavenging port is strong, so the mixed gas advances a sufficient distance in the direction specified by the scavenging angle adjustment elastic member, and even during high-speed rotation, the mixed gas blows out from the scavenging port in the combustion chamber. The flow of mixed gas from will be appropriate.

〔Example〕

Hereinafter, the present invention will be described with reference to embodiments shown in the drawings.

In FIG. 1, the scavenging passage 30 has an outer corner side i42 that is farther from the exhaust port 26 and an inner corner side wall 44 that is closer to the exhaust port 26 in the vicinity of the scavenging port 28, and both the outer corner side wall 42 and the inner corner side wall 44 are , are oblique to the scavenging port 28 so as to face in a direction away from the exhaust port 26.

The scavenging angle adjustment elastic plate 46 is made of an elastically deformable plate member such as a rubber membrane plate and a thin stainless steel plate, and is arranged at each scavenging port 2.
It is fixed to the outer corner side wall 42 so as to cover the outer corner side wall 42 in the scavenging passage 30 near 8.

FIGS. 2(a) and 2(b) show how the scavenging angle adjusting elastic plate 46 is fixed to the outer corner side wall 42. Figure 2(a)
Here, locking grooves 48, 48 which are bulged at the back are formed at both ends of the outer corner side wall 42 in the cross-sectional direction of the scavenging passage 30, and both bulging ends 50 of the elastic plate 46 for adjusting the scavenging angle are formed.
．． 50 is fitted into the locking grooves 48, 48 and locked, thereby fixing the scavenging angle adjusting elastic plate 46 to the outer corner side wall 42. In FIG. 2(b), both ends of the elastic plate 46 for adjusting the scavenging angle in the cross-sectional direction of the scavenging passage 30 are placed against the outer corner side wall 42, and both ends are fixed to the outer corner side u42 by screws 52. There is.

Returning to FIG. 1, the outer corner side extension surface 54 is a plane extending the scavenging angle adjusting elastic plate 46 in the free state toward the combustion chamber 12, and the inner corner side extension surface 56 is a plane extending from the inner corner side side wall 44. This is a plane extending toward the combustion chamber 12. C2 is defined as the intersection line of both outer corner side extension surfaces 54, 54, and is near a point on the opposite side of the exhaust port 26 with respect to the center of the combustion chamber 12, and extends slightly radially outward from that point. It is in position.

FIG. 3 shows the relationship between the position of the piston 14 and the mixed gas pressure in the crankcase 16. When the two-cycle engine rotates at high speed, a large amount (in terms of weight) of mixed gas is sucked into the crankcase 16, and the piston 14
It is understood that the mixed gas pressure in the crankcase 16 during the scavenging stroke is higher than that during low speed rotation because of the high moving speed.

FIGS. 4(a) and 4(b) show the condition of the scavenging angle adjusting elastic plate 46 and the flow condition of the mixed gas in the combustion chamber 12 when the two-cycle engine rotates at low speed. At low speed rotation of a two-cycle engine, as explained in Figure 3,
The mixed gas pressure within the crankcase 16, that is, within the scavenging passage 30, is low.

The amount of mixed gas flowing into the combustion chamber 12 (in terms of weight) is small, so the collision force of the mixed gas hitting the scavenging angle adjusting elastic plate 46 is small, and the scavenging angle adjusting elastic plate 46 has a small collision force.

The plate 46 is in a substantially undeformed state. Thereby, the mixed gas flows into the combustion chamber 12 from the scavenging port 28 along the outer corner side extension surface 54. However, the force of the mixed gas blowing out from the scavenging port 28 is weak, and therefore, the mixed gas tends to bend toward the exhaust port 26 as soon as it flows into the combustion chamber 12. As a result, this tendency to bend easily and the direction provided by the scavenging angle adjustment elastic plate 46 cancel each other out, and the flow of the mixed gas from the scavenging port 28 in the combustion chamber 12 is controlled at the low speed rotation shown in FIG. 4(b). The apex of the actual inflow range 58 at low speeds far from the center of the combustion chamber 12, as indicated by the actual inflow range 58, is approximately the same as the position of C1 defined in FIG. Therefore, the mixed gas that has flowed into the combustion chamber 12 reaches sufficiently close to C1, and after reaching sufficiently close to C1, the gas mixture flows into the exhaust port 26.
Since the direction is changed toward remain in the

FIGS. 5(a) and 5(b) show the condition of the scavenging angle adjusting elastic plate 46 and the flow condition of the mixed gas in the combustion chamber 12 when the two-cycle engine rotates at high speed. When a two-cycle engine rotates at high speed, as explained in Figure 3,
The mixed gas pressure within the crankcase 16, that is, within the scavenging passage 30, is high.

The amount of mixed gas flowing into the combustion chamber 12 (weight equivalent) is large.
Therefore, the collision force of the mixed gas hitting the scavenging angle adjusting elastic plate 46 is large, and the scavenging angle adjusting elastic plate 46 curves convexly toward the outer corner side wall 42 due to the collision force of the mixed gas.

The actual inflow range 60 during high speed rotation in FIG.
The actual inflow range at both high speed rotations is 60.
The apex of is almost the same as the position of C1 defined in FIG. Thereby, the mixed gas flows into the combustion chamber 12 from the scavenging port 28 along the actual inflow range 60 during high speed rotation. When the two-cycle engine rotates at high speed, the force of the mixed gas blowing out from the scavenging port 28 is strong, so the inside corner side wall 34
The mixed gas flowing into the combustion chamber 12 from the scavenging port 28 with its blowing direction regulated by the scavenging angle adjusting elastic plate 46 flows within the range between the inner corner side extension surface 56 and the actual inflow range 60 at high speed rotation. Go straight until it is close enough to C1
After reaching sufficiently close to , the direction is changed toward the exhaust port 26 . As a result, the burned gas within the combustion chamber 12 is efficiently expelled toward the exhaust port 26, and remains within the combustion chamber 12 without immediately exiting from the combustion chamber 12 through the exhaust port 26.

〔Effect of the invention〕

As described above, according to the present invention, the elastic member for adjusting the scavenging angle which can be elastically deformed is disposed in the scavenging passage near the scavenging port,
The scavenging angle adjustment elastic member is elastically deformed by the force of collision with the mixed gas that is related to the rotational speed of the two-cycle engine. Directs the mixed gas farther from the exhaust port than during high-speed rotation when the force of the gas blowout is large. As a result, the direction of the mixed gas toward the combustion chamber by the elastic member for scavenging angle adjustment and the tendency of the mixed gas to curve toward the scavenging port cancel each other out, and the mixed gas becomes independent of the rotational speed of the two-cycle engine. can flow inside the combustion chamber in the proper path.

As a result, the scavenging effect of the burned gas by the mixed gas in the combustion chamber and the filling efficiency of the mixed gas into the combustion chamber can be improved, and it is possible to increase the output of the two-cycle engine and reduce fuel consumption. .

Since the scavenging angle adjusting elastic member curves due to collision with the mixed gas, the mixed gas can flow along the scavenging angle adjusting elastic member without separating from it, reducing the flow path resistance in the scavenging passage near the scavenging port. can be reduced.

[Brief explanation of the drawing]

1 to 6 relate to embodiments of the present invention. Figure 1 is a cross-sectional view of the cylinder at a height including the exhaust port and the scavenging port, Figures 2 (a) and (b) are views showing how the elastic plate for adjusting the scavenging angle is fixed to the outer corner side wall, and Figure 3 The figure shows the relationship between the piston position and the mixed gas pressure in the crankcase. Figures 4 (a) and (b) show the state of the scavenging angle adjusting elastic plate and the combustion chamber during low speed rotation of a two-cycle engine. 5(a) and (b) are diagrams showing the state of the elastic plate for scavenging angle adjustment and the flow state of the mixed gas in the combustion chamber during high speed rotation of a two-cycle engine, FIG. 6 is an overall schematic diagram of a two-cycle engine, FIGS. 7 and 8 are related to a conventional scavenging device for a two-cycle engine, and FIG. 7 is a cross-sectional view of a cylinder at a height including an exhaust port and a scavenging port; FIGS. 8(a) and 8(b) are diagrams showing the flow of mixed gas in the combustion chamber during high-speed rotation and low-speed rotation, respectively, in the two-cycle engine of FIG. 7. 12... Combustion chamber, 26... Exhaust port, 28... Scavenging port, 30... Scavenging passage, 46... Elastic plate for adjusting the scavenging angle. 26...Exhaust port 28...Scavenging port 3o...Scavenging passage 46...Elastic plate point for adjusting the scavenging angle Point 4
Figures (a) (b) Figure 5 (a) (b) Figure 7 Procedural Negotiations (spontaneous) March 2, 1986 Commissioner of the Japan Patent Office Black 1) Mr. Akio ■, Indication of the incident 1986 Patent Application No. 019670 2, Title of the Invention -1+ Otsuhenicycle Engine Scavenging Device 3, Relationship with the Compensation Person Case Name of Patent Applicant Name Maruyama Seisakusho Co., Ltd. 4, Agent (6, Contents of the amendment) "During rotation," on page 7, line 16 of the specification is corrected as follows: "During rotation."

Claims (1)

[Claims] In a scavenging device for a two-stroke engine in which a scavenging port and an exhaust port open into a combustion chamber, and a mixed gas is introduced into the combustion chamber from a scavenging passage through the scavenging port, elasticity is determined in relation to the collision force with the mixed gas. A scavenging angle adjusting elastic member that directs the mixed gas away from the exhaust port as it deforms and its collision force decreases is disposed in the scavenging passage near the scavenging port. A scavenging device for a two-stroke engine.