JP2010216314A - Two-stroke engine and engine tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a two-stroke engine which lowers pollution, enhancing the fuel consumption and the productivity. <P>SOLUTION: A cylinder body 22 has a partition wall 36 to partition a scavenging passage outlet 32 into two outlets 32a and 32b, and a scavenging passage cover 40 has a projection 400 at a position facing the partition wall 36, and a scavenging passage 35 is formed in a space partitioned into the scavenging passage cover 40 and the cylinder body 22. The scavenging passage 35 is split into two scavenging passages 35a and 35b, because the projection 400 has an end face in such a manner as covering the partition wall 36 and recessed end faces of the partition wall 36 and the projection 400 are arranged so as to overlap vertically in the flow-in direction of mixture gas into a combustion chamber 28. Therefore, the scavenging passage cover 40 and the cylinder body 22 are not required to have a high dimensional accuracy, and the mixture gases flowing into the combustion chamber 28 from the scavenging passage outlets 32a and 32b do not interfere with each other. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a two-stroke engine and an engine tool.

In recent years, low-pollution engines have been required by suppliers and consumers due to legal regulations and increasing environmental awareness. Low-pollution engines can lead to improved fuel economy and reduced exhaust gas levels. Appropriate engine scavenging is achieved by forming scavenging passages in various shapes, allowing the air-fuel mixture to flow in the desired flow into the combustion chamber, generating tumble and swirl, etc. There is a way to set.
In addition, the scavenging passage of the conventional two-stroke engine is generally formed by only one part of a cylinder formed mainly by casting. As described above, when the scavenging passage is formed only by the cylinder, it is difficult to process the details of the cylinder, and it is difficult to change the shape of the cylinder in accordance with the design change due to the improvement of fuel consumption. In particular, a cylinder formed by casting has a limited shape due to die cutting from a mold, and is difficult to process.
An engine having a scavenging hole portion formed separately from a cylinder is disclosed in Patent Document 1 in order to easily perform precise machining.

  The scavenging hole portion of the two-stroke engine disclosed in Patent Document 1 has a partition wall that protrudes toward the combustion chamber and divides the scavenging hole into a plurality of parts. Thus, the combustion efficiency is improved by generating a laminar laminar air flow composed of a plurality of flows in the air-fuel mixture flowing into the combustion chamber of the cylinder through the scavenging holes.

JP 59-134323 A

  However, with the technique disclosed in Patent Document 1, it has been difficult to generate a scavenging air flow as simulated during design. This is because it is difficult to divide the air-fuel mixture into a plurality of completely independent flows by the partition wall of the scavenging hole part because the partition wall of the scavenging hole part and the cylinder are separated from each other. This is because the quality is changed to a scavenging air different from the intended scavenging airflow. In addition, due to mutual interference between individual scavenging airflows, the flow changes into an unintended flow.For example, the scavenging airflow that flows into the combustion chamber leaks from the exhaust port before burning, and the combustion efficiency is reduced. Sometimes it was lowered.

On the other hand, it can be considered that the flow of the air-fuel mixture flowing from the scavenging holes into the combustion chamber is divided by forming a partition wall of the scavenging hole in the vicinity of the piston sliding in the cylinder. However, if the partition wall of the scavenging hole part comes into contact with the piston, it may cause a malfunction in the operation of the piston. Therefore, high dimensional accuracy is required for molding the partition wall of the scavenging hole part, and productivity is increased. It will be lower.
As a result, it becomes difficult to estimate the flow of the air-fuel mixture at the engine design stage, it is difficult to obtain an engine with high combustion efficiency, and it is difficult to improve fuel consumption.

  The present invention has been made in view of such problems, and an object of the present invention is to reduce the pollution of a two-stroke engine and to improve fuel consumption and productivity.

A two-stroke engine according to a first aspect of the present invention is:
An engine body having a crank chamber and a combustion chamber, in which a scavenging passage inlet opened in the crank chamber and a scavenging passage outlet opened in the combustion chamber are formed;
A scavenging passage cover that covers a part of the engine body including the scavenging passage inlet and the scavenging passage outlet and forms a scavenging passage;
With
The engine body includes a first partition wall in a portion located in the scavenging passage,
The scavenging path cover includes a second partition wall in a portion located in the scavenging path and facing the first partition wall,
The first partition and the second partition are a two-stroke engine that divides the scavenging passage into a plurality of parts,
The first partition wall and the second partition wall are overlapped in a direction perpendicular to the flow direction of the air-fuel mixture from the scavenging passage outlet to the combustion chamber;
It is characterized by that.

  For example, in a portion where the first partition and the second partition overlap each other in a direction perpendicular to the flow direction of the mixture, the second partition is in a direction perpendicular to the flow direction of the mixture. And facing the scavenging path located at least on the exhaust port side among the divided scavenging paths.

Furthermore, the first partition has a convex end facing the second partition,
The second partition wall has a concave end facing the first partition wall,
It is preferable that the convex end and the concave end overlap each other in a direction perpendicular to the flow direction of the air-fuel mixture.

Further, the engine body has an exhaust port for exhausting the air-fuel mixture after combustion into the combustion chamber,
It is desirable that at least a pair of the scavenging passage outlets are provided on both the left and right sides sandwiching the exhaust port, and the scavenging passage outlets are disposed so as to face a location opposite to the location where the exhaust port is provided in the combustion chamber.

  Furthermore, it is preferable that the first partition and the second partition are provided at least in the vicinity of the scavenging passage outlet in the scavenging passage.

  The engine body may be a cast product.

An engine tool according to a second aspect of the present invention is:
A two-stroke engine according to any one of the above is provided.

  According to the present invention, it is possible to reduce the pollution of a two-stroke engine and to improve fuel consumption and productivity.

It is a mimetic diagram showing an engine tool concerning a 1st embodiment. It is a side view showing the state where the scavenging way cover of the 2-stroke engine concerning a 1st embodiment was attached. It is a side view showing the state where the scavenging way cover of the 2-stroke engine concerning a 1st embodiment was removed. It is an AA cross-sectional arrow view in FIG. 2 which shows the scavenging path exit of the 2-stroke engine which concerns on 1st Embodiment. It is a BB cross-sectional arrow view in FIG. 4 which shows the scavenging path of the 2-stroke engine which concerns on 1st Embodiment. It is sectional drawing which expands FIG. 4 and shows the scavenging path exit of the 2-stroke engine which concerns on 1st Embodiment. It is CC sectional drawing in FIG. 4 explaining the opening timing of the scavenging path exit of the 2-stroke engine which concerns on 1st Embodiment. It is sectional drawing which shows the scavenging path exit of the 2-stroke engine which concerns on 2nd Embodiment. It is sectional drawing which shows the scavenging path exit of the 2-stroke engine which concerns on 3rd Embodiment. It is sectional drawing which shows the scavenging path exit of the 2-stroke engine which concerns on 4th Embodiment.

  Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings.

<First Embodiment>
As shown in FIG. 1, the engine chainsaw 10 according to the present embodiment is mainly composed of a tool main body 12, a blade portion 14, a handle 16, and a two-stroke engine (hereinafter referred to as an engine) 20. .
The tool main body 12 has an engine 20 inside, and supports a blade portion 14 described later rotatably. Furthermore, a recoil starter 18 used for starting the engine 20 is provided.
The blade portion 14 is sharply formed in a chain shape, and is connected to a crankshaft (not shown) of the engine 20 via a centrifugal clutch (not shown). When the engine 20 reaches a predetermined number of revolutions or more, the centrifugal clutch transmits the power from the engine 20 so that the blade portion 14 is driven to rotate.
The handle 16 includes a throttle lever 160 that increases the rotational speed of the engine 20, and is formed to protrude from the tool body 12.

Next, the engine 20 will be described mainly with reference to FIGS. FIG. 2 is a view showing a side surface of the engine 20 and shows a state where a scavenging passage cover 40 described later is attached. FIG. 3 is a view showing a side surface of the engine 20 and shows a state where the scavenging passage cover 40 is removed. 3 shows a state in which the engine 20 shown in FIG. 2 is rotated by a predetermined angle in the circumferential direction so that the portion where the scavenging passage cover 40 is removed can be visually recognized.
As shown in FIGS. 2 and 3, the engine 20 includes a cylinder body 22, a crankcase (not shown), a set of scavenging passage covers 40, and a piston 70 (see FIG. 7).

The cylinder body 22 is formed by casting such as aluminum die casting. The cylinder body 22 includes an intake port 24 and an exhaust port 26, a pair of scavenging passages 35 having a scavenging passage inlet 30 and a scavenging passage outlet 32 to be described later, and a crank chamber 21 and a scavenging passage cover 40 in the lower part of the figure. Projecting walls 220 projecting from the periphery of the housing.
The crank chamber 21 has a crankshaft (not shown) connected to the piston 70 inside. The crankshaft is rotated through a connecting rod (not shown) by the vertical movement of the piston 70. As the crankshaft rotates, the blade portion 14 (see FIG. 1) rotates via a cam (not shown). Further, the crank chamber 21 accumulates a mixture of gasoline and air that flows in through the intake port 24.
The scavenging passage inlet 30 communicates with the crank chamber 21. The air-fuel mixture introduced into the crank chamber 21 from the intake port 24 flows into the scavenging passage 35 through the scavenging passage inlet 30.
The scavenging passage outlet 32 communicates with the combustion chamber 28 (see FIG. 7) and is divided into a scavenging passage outlet 32a and a scavenging passage outlet 32b with a partition wall 36 formed in the cylinder body 22 as a boundary. Further, the scavenging path 35 is divided into a scavenging path 35a and a scavenging path 35b by a partition wall 36 and a projection 400 formed on the scavenging path cover 40 described later.

  The scavenging path cover 40 is formed by casting such as aluminum die casting. The scavenging path cover 40 is fixed to the cylinder body 22 with bolts or the like in a state where it is in contact with the protruding wall 220. The scavenging path 35 is partitioned by the scavenging path cover 40 and the cylinder body 22.

4, the cross section on the scavenging passage outlet 32 of the cylinder body 22 is shown in FIG. As shown in the figure, a set of scavenging passages 35 having the same shape symmetrically with respect to a plane including the center axis of the cylinder body 22 and the center of the exhaust port 26 (hereinafter referred to as a cylinder symmetry plane) It is formed by the protruding wall 220 of the cylinder body 22 and the scavenging path cover 40.
As shown in FIG. 4, the scavenging path outlets 32 a and 32 b of the scavenging path 35 are directed so that the air-fuel mixture flows into the inner surface of the cylinder body 22 facing the exhaust port 26. In FIG. 4, the respective air-fuel mixtures from the scavenging passage outlets 32a and 32b to the combustion chamber 28 are indicated by arrows indicating the inflow directions 50 and 52 (the same applies to FIGS. 6, 8, 9 and 10 described later). As shown in the drawing, the air-fuel mixture flows into the combustion chamber 28 along the wall surface of the scavenging passage outlets 32a and 32b on the side facing the exhaust port 26.

Next, referring to FIG. 6 showing an enlarged view of FIG. 4, a partition wall 36 formed in the cylinder body 22 so as to divide the scavenging passage outlet 32 into a scavenging passage outlet 32a and a scavenging passage outlet 32b, and a scavenging passage. The protrusion 400 formed on the cover 40 will be described in detail.
The partition wall 36 is formed integrally with the cylinder body 22 and separates the scavenging path outlet 32 into a scavenging path outlet 32a and a scavenging path outlet 32b. The wall surface of the scavenging path outlet 32a and the scavenging path outlet 32b separated by the partition wall 36 on the side facing the exhaust port 26 faces the inner surface of the cylinder body 22 on the side facing the exhaust port 26 (see FIG. 4). Each is formed at a different angle.
The protrusion 400 is formed to protrude from the inner surface of the scavenging path cover 40 on the scavenging path 35 side (combustion chamber 28 side) to face the partition wall 36. The end surface of the protrusion 400 facing the partition wall 36 is formed in a concave shape.
In a state where the scavenging path cover 40 is attached to the cylinder body 22, the circumferential surface of the partition wall 36 and the concave end surface of the protrusion 400 overlap perpendicularly to the inflow directions 50 and 52 of the air-fuel mixture into the combustion chamber 28 (hereinafter referred to as polymerization). Are described as follows. For this reason, the scavenging path 35 leading to the combustion chamber 28 of the cylinder body 22 is divided into the scavenging path 35a and the scavenging path 35b, and the inflow of the air-fuel mixture flowing through the scavenging path 35a and the scavenging path 35b is prevented.

Next, the flow of each scavenging air flow from the scavenging passage 35a and the scavenging passage 35b to the combustion chamber 28 will be described.
7, the scavenging path outlet 32a and the scavenging path outlet 32b communicate with the inside of the combustion chamber 28 by the lowering of the piston 70 during operation of the engine 20. As shown in FIG. In the present embodiment, the height position of the upper surface of the scavenging path outlet 32a is lower than the height position of the upper surface of the scavenging path outlet 32b. Since it is formed in this way, the timing at which the scavenging passage outlets 32a and 32b communicate with the combustion chamber 28 is shifted. As a result, the timing at which the air-fuel mixture flows into the combustion chamber 28 also shifts. In this way, when the exhaust gas flows back to the crank chamber 21 side, most of the exhaust gas is retained at the scavenging passage outlet 32b that opens first, and then flows into the combustion chamber 28 from the scavenging passage outlet 32a that opens later. Qi concentration can be maintained.

Next, the operation and effect of this embodiment will be described.
First, the engine 20 starts when the recoil starter 18 provided in the engine chain saw 10 shown in FIG. 1 is pulled. As shown in FIG. 7, the air-fuel mixture is sucked into the crank chamber 21 through the air inlet 24. The air-fuel mixture filled in the crank chamber 21 flows into the combustion chamber 28 via the scavenging passage 35 (see FIG. 5). Most of the air-fuel mixture flowing into the combustion chamber 28 from the scavenging path outlets 32a and 32b faces the exhaust port 26 of the cylinder body 22 along the wall surface of the scavenging path outlets 32a and 32b on the side facing the exhaust port 26. The exhaust gas is scavenged by colliding with the air-fuel mixture flowing in from the scavenging passage 35 provided symmetrically on the cylinder symmetry plane toward the inner surface on the side and moving upward and reversing toward the exhaust port 26 side. At this time, as the piston 70 descends, the scavenging passage outlet 32b communicates with the combustion chamber 28, and then the scavenging passage outlet 32a communicates. Due to this time lag, the air-fuel mixture first flows into the combustion chamber 28 via the scavenging passage outlet 32b, and then the air-fuel mixture flows into the combustion chamber 28 via the scavenging passage outlet 32a. When the piston 70 rises to the top dead center of the combustion chamber 28, the air-fuel mixture in the combustion chamber 28 is compressed and burned by a spark generated from a spark plug (not shown). When the piston 70 is lowered to a predetermined position, the air-fuel mixture after combustion is pushed out by the scavenging air flowing from the scavenging passage outlet 32 as exhaust gas and discharged through the exhaust port 26. By repeating this cycle, the engine 20 repeatedly supplies rotational power to the blade portion 14.
Further, transmission of power from the engine 20 to the blade portion 14 will be described. When the throttle lever 160 of the engine chain saw 10 is pushed, the amount of air-fuel mixture sent into the combustion chamber 28 increases. When the amount of the air-fuel mixture increases, the rotation speed of the piston 70 increases. When the crankshaft connected to the piston 70 rotates at a predetermined rotational speed or more, the centrifugal clutch transmits power to the blade portion 14.

  Since the concave end surface of the projection 400 formed on the scavenging passage cover 40 is formed so as to cover the partition wall 36 formed on the cylinder body 22, the air-fuel mixture flows between the scavenging passage 35a and the scavenging passage 35b. For this purpose, the air flow must flow in the opposite direction with respect to the inflow directions 50 and 52 of the air-fuel mixture from the scavenging passage 35 to the combustion chamber 28. Substantially this reverse flow cannot occur with high inflow resistance. Therefore, it is possible to suppress the generation of a flow communicating between the scavenging passage 35a and the scavenging passage 35b.

  As described above, when the partition 36 and the protrusion 400 suppress the generation of a flow that communicates between the scavenging passage 35a and the scavenging passage 35b, the flow of the air-fuel mixture is generated as expected in the design stage. Can do. In this way, a design that prevents the air-fuel mixture flowing into the combustion chamber 28 from leaking from the exhaust port 26 before combustion can be suitably reflected in the engine 20, reducing the pollution of the engine 20 and reducing fuel consumption. Can be improved.

  In the present embodiment, the scavenging passage 35 is not integrally formed in the cylinder body 22, but the scavenging passage 35 is formed by the scavenging passage cover 40 and the cylinder body 22. By doing in this way, the shape of the scavenging path 35 can be changed only by changing the shape of the scavenging path cover 40. If it does so, it will become possible to manufacture the engine 20, performing the change of a detailed shape only to the scavenging passage cover 40 by the cut and try led by analysis. By doing so, scavenging airflows having a wide variety of flows can be easily generated.

  In this way, when the air-fuel mixture flow is separated using the partition wall 36 and the protrusion 400, higher dimensional accuracy is not required as compared with the case where only the protrusion 400 extends to the vicinity of the movable range of the piston 70. The inflow of the air-fuel mixture between the scavenging path outlet 32a and the scavenging path outlet 32b can be prevented. Therefore, the scavenging path cover 40 can be molded in large quantities by die casting or the like. Furthermore, the cylinder main body 22 and the scavenging path cover 40 can be formed into a shape that can be easily punched out, compared to a case in which the scavenging path 35 is integrated with the cylinder main body 22, and the manufacturing cost can be reduced.

  The overlapping portion of the partition wall 36 and the projection 400 may be positioned at least in the vicinity of the scavenging passage outlet 32 so as to cut off the flow of the air-fuel mixture to the combustion chamber 28. However, the scavenging passage 35 is cut off as a whole. You may do it.

<Second Embodiment>
The present invention is not limited to the shape of the protrusion 400 and the partition wall 36 according to the first embodiment, and may have other shapes.

With reference to FIG. 8, the protrusion 420 and the partition 37 which concern on 2nd Embodiment are demonstrated.
The end surface on the radially outer side of the partition wall 37 formed in the cylinder body 22 is formed in a concave shape.
An end face of the projection 420 formed on the scavenging path cover 42 facing the partition wall 37 is formed in a convex shape.
In a state where the scavenging path cover 42 is attached to the cylinder body 22, the protrusion 420 is formed so as to be opposed to the partition wall 37 provided on the cylinder body 22. That is, the end surface of the protrusion 420 is disposed so as to be covered with the concave end surface of the partition wall 37.

  As described above, even if the end face of the protrusion 420 is arranged so as to be covered with the concave end face of the partition wall 37, the scavenging passages 35 a and 35 b are provided if the inflow resistance of the overlapping portion between the partition wall 37 and the protrusion 420 is high. Inflow of the air-fuel mixture flowing through each other is prevented.

  For example, the overlapping portion of the partition wall 37 and the protrusion 420 is lengthened, the surface of the protrusion 420 facing the partition wall 37 and the surface finish of the surface of the partition wall 37 facing the protrusion 420 are finished to a predetermined roughness, By increasing the contact area of the surface, the inflow resistance can be increased.

<Third Embodiment>
The present invention is not limited to the shapes of the protrusions 400 and 420 and the partition walls 36 and 37 according to the first embodiment and the second embodiment, but may have other shapes.

With reference to FIG. 9, the protrusion 440 and the partition wall 38 according to the third embodiment will be described.
The radially outer end of the partition wall 38 formed in the cylinder body 22 is formed in a triangular prism shape.
An end portion of the projection 440 formed on the scavenging path cover 44 that faces the partition wall 38 is also formed in a triangular prism shape.
In a state where the scavenging path cover 44 is attached to the cylinder body 22, one surface of the end portion of the protrusion 440 facing the partition wall 38 is disposed to face one surface of the radially outer end portion of the partition wall 38. Here, one side of the overlapping surface of the protrusion 440 and the partition wall 38 is arranged on the scavenging path 35a on the scavenging path 35 side, and one side of the scavenging path 35b facing the combustion chamber 28 side is arranged.

  Even in such a configuration, if the inflow resistance of the overlapping portion between the partition wall 38 and the protrusion 440 is high, the inflow of the air-fuel mixture flowing through the scavenging passages 35a and 35b can be prevented. For example, the overlapping portion of the partition wall 38 and the projection 440 is lengthened, the surface of the projection 440 facing the partition wall 38 and the surface finish of the surface of the partition wall 38 facing the projection 440 are finished to a predetermined roughness, By increasing the contact area of the surface, the inflow resistance can be increased.

  Further, the partition wall 38 may be formed so that the distance between the surface of the projecting wall 220 of the cylinder body 22 facing the scavenging path 35b and the surface of the partition wall 38 facing the scavenging path 35b decreases as the distance from the combustion chamber 28 approaches. desirable.

Next, an operation for preventing mutual interference between the air-fuel mixture passing through the scavenging passage 35a and the air-fuel mixture passing through the scavenging passage 35b will be described. The inflow of the air-fuel mixture from the scavenging passage 35a to the scavenging passage 35b through the overlapping portion of the partition wall 38 and the protrusion 440 must flow in the opposite direction to the inflow direction 52 of the air-fuel mixture from the scavenging passage 35a to the combustion chamber 28. It must be difficult to occur. For this reason, the inflow of the air-fuel mixture from the scavenging path 35a to the scavenging path 35b can be suppressed.
On the other hand, the inflow of the air-fuel mixture from the scavenging passage 35b to the scavenging passage 35a through the overlapping portion of the partition wall 38 and the protrusion 440 is opposite to the inflow direction 50 of the air-fuel mixture from the scavenging passage 35b to the combustion chamber 28. It can happen because it is not a flow. However, as described above, the partition wall 38 is configured such that the distance between the surface of the protruding wall 220 of the cylinder body 22 facing the scavenging path 35b and the surface of the partition wall 38 facing the scavenging path 35b decreases as the distance from the combustion chamber 28 approaches. Therefore, the air-fuel mixture passing through the scavenging passage 35b flows into the combustion chamber 28 along the protruding wall 220 away from the overlapping portion of the partition wall 38 and the projection 440, and from the scavenging passage 35b to the scavenging passage 35a. Inflow of the air-fuel mixture is suppressed.

<Fourth Embodiment>
In the above-described embodiment, the scavenging path 35 is divided into the scavenging path 35a and the scavenging path 35b, and the protrusions 400 and 420 formed to protrude from the partition walls 36, 37, and 38 and the scavenging path covers 40, 42, and 44, respectively. However, the present invention is not limited to this configuration.
For example, as shown in FIG. 10, the partition 39 protruding so as to overlap the scavenging passage cover 46, and the scavenging passage cover 46 having a groove 460 formed along the end surface of the partition 39 facing the scavenging passage cover 46. You may make it comprise from these.

As described above, the embodiment of the present invention has been described, but the protrusion provided on the scavenging passage cover and the partition wall provided on the cylinder main body overlap each other with a concave end surface and a convex end surface. As described above, the air-fuel mixture flowing into the combustion chamber has been described as being divided, but it may be an end face formed with a plurality of concave portions and a plurality of convex portions facing the concave portions. By doing in this way, the change of the directionality of the air-fuel mixture which tends to flow between the divided scavenging passages can be increased, and the inflow resistance can be increased.
In addition, the number of partition walls provided in the cylinder main body is one. However, a plurality of partition walls may be provided, and a protrusion corresponding to the partition wall may be provided on the scavenging passage cover to divide the scavenging passage outlet into three or more. By doing in this way, it can comprise in the scavenging path with a higher degree of freedom.

  Although an engine chain saw has been described as an embodiment of the engine tool according to the present invention, the present invention is not limited thereto, and the present invention may be applied to a tool including an engine such as a blower or a brush cutter.

10: Engine chainsaw (engine tool)
20: Engine 21: Crank chamber 22: Cylinder body (engine body)
24: Intake port 26: Exhaust port 28: Combustion chamber 30: Scavenging channel inlet 32, 32a, 32b: Scavenging channel outlet 35, 35a, 35b: Scavenging channel 36, 37, 38, 39: Partition (first partition)
40, 42, 44: scavenging passage cover 400, 420, 440: protrusion (second partition)
460: groove (second partition)

Claims (7)

An engine body having a crank chamber and a combustion chamber, in which a scavenging passage inlet opened in the crank chamber and a scavenging passage outlet opened in the combustion chamber are formed;
A scavenging passage cover that covers a part of the engine body including the scavenging passage inlet and the scavenging passage outlet and forms a scavenging passage;
With
The engine body includes a first partition wall in a portion located in the scavenging passage,
The scavenging path cover includes a second partition wall in a portion located in the scavenging path and facing the first partition wall,
The first partition and the second partition are a two-stroke engine that divides the scavenging passage into a plurality of parts,
The first partition wall and the second partition wall are overlapped in a direction perpendicular to the flow direction of the air-fuel mixture from the scavenging passage outlet to the combustion chamber;
A two-stroke engine characterized by that. In the portion where the first partition and the second partition overlap each other in a direction perpendicular to the flow direction of the air-fuel mixture, the second partition wall is in the direction perpendicular to the flow direction of the air-fuel mixture. Of the plurality of divided scavenging paths, facing the scavenging path side located at least on the exhaust port side,
The two-stroke engine according to claim 1. The first partition has a convex end facing the second partition,
The second partition wall has a concave end facing the first partition wall,
The convex end portion and the concave end portion are positioned so as to overlap in a direction perpendicular to the flow direction of the air-fuel mixture.
The two-stroke engine according to claim 1 or 2, characterized in that. The engine body has an exhaust port for exhausting the air-fuel mixture after combustion into the combustion chamber,
The scavenging path outlets are provided at least as a pair on both the left and right sides sandwiching the exhaust port, and are disposed facing a location facing the location where the exhaust port is provided in the combustion chamber.
The two-stroke engine according to any one of claims 1 to 3, wherein the two-stroke engine is provided. The first partition and the second partition are provided at least in the vicinity of the scavenging passage outlet in the scavenging passage,
The two-stroke engine according to any one of claims 1 to 4, wherein the two-stroke engine is provided. The engine body is a cast product,
The two-stroke engine according to any one of claims 1 to 5, characterized by the above-mentioned. The two-stroke engine according to claim 1 is provided.
An engine tool characterized by that.

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