JP6411159B2 - Air-driven stratified scavenging two-cycle internal combustion engine - Google Patents

Description

  The present invention relates generally to two-cycle internal combustion engines, and more particularly to an air-leading engine that first introduces air into a combustion chamber during a scavenging stroke.

  Two-cycle internal combustion engines are frequently used in portable work machines such as brush cutters and chainsaws. This type of two-cycle internal combustion engine has a scavenging passage communicating the crank chamber and the combustion chamber. The air-fuel mixture precompressed in the crank chamber is introduced into the combustion chamber through the scavenging passage, and scavenging is performed by this air-fuel mixture.

As is well known, a two-cycle engine of the type that scavenges with an air-fuel mixture has a problem of “blown air (fresh air)”. To solve this problem, an air-leaded stratified scavenging two-cycle internal combustion engine has been proposed and already put into practical use (Patent Document 1) . The air-leading stratified scavenging engine fills the scavenging passage with air prior to scavenging. In the scavenging stroke, air in the scavenging passage is first discharged into the combustion chamber, and then the air-fuel mixture in the crank chamber is introduced into the combustion chamber through the scavenging passage.

  FIG. 14 is a diagram related to a conventional air-leading stratified scavenging engine. In FIG. 14, the illustration of the piston is omitted in order to avoid complication of the diagram. In the figure, reference numeral 100 indicates a cylinder wall. An air passage 102 and an air-fuel mixture passage (not shown) are opened in the cylinder wall 100. The air port is illustrated by reference numeral 102a. A scavenging port 104 a of the scavenging passage 104 is also opened in the cylinder wall 100. The scavenging passage 104 communicates with the crank chamber. Both the air port 102a and the scavenging port 104a are opened and closed by a piston. The piston has a groove 106 on its peripheral surface. The piston groove 106 extends in the circumferential direction.

  (I) to (III) in FIG. 14 show the state in the process of raising the piston, and (II) in FIG. 14 shows the state in which the piston is raised more than (I) in FIG. (III) in FIG. 14 shows a state where the piston is raised from the position (II) in FIG.

  Referring to (I) of FIG. 14, blow-back gas in the previous scavenging is mixed in the piston groove 106. This blow-back gas contains an air-fuel mixture component. Blow-back gas remaining in the piston groove 106 is indicated by dots. As the piston rises from bottom dead center, the crank chamber becomes negative pressure. FIG. 14 (II) shows a state where the piston groove 106 communicates with the air port 102a. In the state of (II) in FIG. 14, the piston groove 106 is not in communication with the scavenging port 104a. For this reason, even if the piston groove 106 communicates with the air port 102a, air does not flow into the piston groove 106 from the air port 102a. In other words, the blow back gas in the piston groove 106 does not flow.

  (III) of FIG. 14 shows a state where the piston groove 106 communicates with the air port 102a and communicates with the scavenging port 104a. When the piston groove 106 communicates with the scavenging port 104a, air can be supplied from the air port 102a to the scavenging passage 104 via the piston groove 106.

US 6,857,402 B2

  Referring to FIG. 14 (III), in the conventional air-leading stratified scavenging type two-cycle internal combustion engine, theoretically, the piston groove 106 communicates with the scavenging port 104a for the first time in the gas in the piston groove 106. Flow occurs. The gas in the piston groove 106 first enters the scavenging passage 104, and then the air enters the scavenging passage 104 through the piston groove 106 from the air port 102a. Therefore, the timing at which air enters the scavenging passage 104 from the piston groove 106 is later than the timing at which the piston groove 106 begins to communicate with the scavenging passage 104.

  As is well known, a piston valve type is employed in an air-leading two-cycle internal combustion engine for a work machine. That is, the air port 102a, the scavenging port 104a, the exhaust port, and the like are opened and closed by the piston. In the piston valve type engine, the gas flow is controlled by the pressure balance between two spaces or passages that are communicated and blocked via the piston.

  A two-cycle engine for a work machine is operated at a high rotation speed of, for example, 10,000 rpm. For this reason, the timing delay described above has a great influence on the air filling efficiency of the scavenging passage 104. In other words, the conventional stratified scavenging two-cycle engine has an essential problem that it is difficult to ensure the certainty that the scavenging passage 104 is filled with air every cycle.

  In the air-leading stratified scavenging engine, in the scavenging stroke, first, the burned gas is exhausted with air, and then the air-fuel mixture is filled into the combustion chamber. Theoretically, emission characteristics should be greatly improved by adopting an air-leading laminar scavenging method. However, the actual problem is that the effect of improving the emission characteristics is limited due to the above-mentioned essential problems.

  In order to cope with the timing delay described above, it has been proposed that the timing at which the piston groove 106 communicates with the scavenging port 104a is significantly advanced. However, when this configuration is adopted, the air-fuel mixture component remaining in the scavenging passage 104 tends to flow into the air passage 102 side, and the effect of improving the emission characteristics is reduced.

  An object of the present invention is to provide an air-leaded stratified scavenging two-cycle internal combustion engine that can improve the reliability of supplying air to a scavenging passage through a piston groove.

  It is a further object of the present invention to provide an air-driven stratified scavenging two-cycle internal combustion engine that supplies air to a scavenging passage through a piston groove and can improve the reliability of the air supply amount.

  It is a further object of the present invention to provide an air-driven stratified scavenging two-cycle internal combustion engine that supplies air to a scavenging passage through a piston groove and can improve the reliability of the air supply timing.

According to the present invention, the above technical problem is
An air port that opens into the cylinder wall and is opened and closed by a piston;
A scavenging passage having a scavenging port that opens in the cylinder wall and is opened and closed by the piston, the scavenging passage communicating with the crank chamber;
A piston groove formed on a circumferential surface of the piston and capable of communicating the air port and the scavenging port;
A degassing port smaller than the scavenging port that opens to the cylinder wall independently from the scavenging port and is opened and closed by the piston, and supplies air from the air port to the scavenging port through the piston groove A degassing port that communicates with the crank chamber at all times in order to strengthen the initial motion of the air flow ;
The vent port communicates with the scavenging passage;
The degassing port located in the crank chamber side is lower position than the scavenging port,
In the process of raising the piston, the piston groove communicates with the gas vent port in the process of moving the piston from bottom dead center to top dead center, and then communicates with the air port in the process of communicating with the scavenging port. before the piston groove that communicates with the scavenging port, strengthen initial of the air flow the air port and the communicating piston groove through the by the communication with the venting port,
This is achieved by providing an air-driven stratified scavenging two-cycle internal combustion engine characterized in that the piston groove is not in communication with the air port when the piston is at top dead center .

  FIG. 1 is a diagram for explaining the concept of the present invention. Referring to FIG. 1, reference numeral 2 indicates a cylinder wall and corresponds to the cylinder wall 100 shown in FIG. Reference numeral 4 in FIG. 1 denotes an air passage, 4a denotes an air port, and corresponds to the air passage 102 and the air port 102a shown in FIG. Reference numeral 6 in FIG. 1 indicates a scavenging passage, 6a indicates a scavenging port, and corresponds to the scavenging passage 104 and the scavenging port 104a illustrated in FIG. Reference numeral 8 in FIG. 1 denotes a piston groove, which corresponds to the piston groove 106 in FIG.

  Still referring to FIG. 1, a gas vent port 10 is formed in the cylinder wall 2 below and adjacent to the scavenging port 6 a in the cylinder axial direction. The gas vent port 10 is set so as not to open to the combustion chamber when the piston is located at the bottom dead center. That is, the piston located at the bottom dead center is set to close the gas vent port 10. The arrangement position of the gas vent port 10 is preferably located below the upper side of the piston ring of the piston located at the bottom dead center. The degassing port 10 is independent of the scavenging port 6a, and the degassing port 10 is opened and closed by a piston, similarly to the air port 4a and the scavenging port 6a. The gas vent port 10 communicates with the crank chamber through the scavenging passage 6.

  (I) to (III) in FIG. 1 show the state of the process of raising the piston. (II) in FIG. 1 shows a state in which the piston is raised as compared with (I) in FIG. 1 and the piston groove 8 communicating with the air port 4 a communicates with the gas vent port 10. (III) in FIG. 1 shows a state where the piston rises in the cylinder axial direction from the position (II) in FIG. 1 and the piston groove 8 communicates with the scavenging port 6a.

  The crank chamber becomes negative pressure as the piston rises from bottom dead center. In the process of raising the piston, the blow-back gas in the piston groove 8 does not flow until the piston groove 8 communicates with the air port 4a ((I) in FIG. 1). When the piston rises further and the piston groove 8 communicates with the gas vent port 10 ((II) in FIG. 1), the piston groove 8 communicates with the crank chamber via the gas vent port 10. Thereby, the blow-back gas in the piston groove 8 can move to the crank chamber through the gas vent port 10. As the blow back gas in the piston groove 8 flows toward the crank chamber, air can enter the piston groove 8 from the air port 4a.

  That is, when the piston groove 8 communicates with the gas vent port 10, a gas flow from the air port 4 a toward the crank chamber through the gas vent port 10 is generated inside the piston groove 8.

  When the piston further rises and the piston groove 8 communicates with the scavenging port 6a, the gas flow in the piston groove 8 in which the gas flow has already occurred is continued with respect to the scavenging port 6a ((III) in FIG. 1). ). Therefore, the air can enter the scavenging port 6a through the piston groove 8 at the same time as the piston groove 8 communicates with the scavenging port 6a.

  That is, according to the present invention, the piston groove 8 communicates with the negative pressure crank chamber through the gas venting port 10, so that the gas flow in the piston groove 8 occurs before the piston groove 8 communicates with the scavenging port 6 a. Generated. Thereby, at the same time as the piston groove 8 communicates with the scavenging port 6a, the initial movement of the air flow that fills the scavenging port 6a with air through the piston groove 8 can be strengthened. And by strengthening this initial motion, it is possible to increase the certainty that the scavenging passage 6 is filled with air every cycle.

  The piston groove 8 included in the present invention has a height dimension in which the piston groove 8 communicating with the air port 4a simultaneously communicates with the scavenging port 6a and the gas venting port 10 in the process of raising the piston in the cylinder axial direction. (FIG. 2). The piston groove 8 included in the present invention has a height dimension that blocks communication with the air port 4a and the vent port 10 when the piston is located at the top dead center and communicates with the scavenging port 6a. (FIG. 3). The piston groove 8 having this height dimension communicates with the gas vent port 10 first and then with the air port 4a in the process of raising the piston.

  FIG. 4 shows a modification of the engine shown in FIG. The engine shown in FIG. 4 is the same as the engine shown in FIG. 1 in that it has a vent port 10 formed in the cylinder wall 2. The engine shown in FIG. 4 has a pressure transmission through hole 12 formed in the piston groove 8. The pressure transmission through hole 12 is always in communication with the crank chamber.

  4 (I) to (IV) show the state of the process of raising the piston. FIG. 4 (II) shows a state immediately before the piston rises and the piston groove 8 communicates with the air port 4a as compared with FIG. 4 (I). 4 (III) shows a state in which the piston is raised from the position of FIG. 4 (II) and the piston groove 8 communicating with the air port 4a communicates with the gas vent port 10. FIG. (IV) in FIG. 4 shows a state where the piston is raised from the position of (III) in FIG. 4 and the piston groove 8 communicates with the scavenging port 6a.

  The crank chamber becomes negative pressure as the piston rises from bottom dead center. In the process of raising the piston, the negative pressure in the crank chamber affects the piston groove 8 through the pressure transmission through hole 12. As a result, the pressure inside the piston groove 8 starts to decrease, and the blow-back gas in the piston groove 8 starts to flow along with the pressure decrease ((II) in FIG. 4).

  When the piston rises and the piston groove 8 communicates with the gas vent port 10 ((III) in FIG. 4), the blow back gas in the piston groove 8 can move to the crank chamber through the gas vent port 10. As the gas in the piston groove 8 flows toward the crank chamber, air can enter the piston groove 8 from the air port 4a.

  When the piston further rises and the piston groove 8 communicates with the scavenging port 6a, the gas flow in the piston groove 8 where the gas flow has already occurred is continued with respect to the scavenging port 6a ((IV) in FIG. 4). ). Therefore, the air can enter the scavenging port 6a through the piston groove 8 simultaneously with the piston groove 8 communicating with the scavenging port 6a.

  According to the present invention, the flow of gas can be started inside the piston groove 8 before the piston groove 8 communicates with the scavenging passage 6. As a result, gas can flow into the scavenging passage 6 through the piston groove 8 at the same time as the piston groove 8 communicates with the scavenging passage 6. Therefore, the certainty of filling the scavenging passage 6 with air through the piston groove 8 can be improved.

  Other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments of the present invention.

It is a figure for demonstrating the structure and effect | action of invention, (I) shows the state just before a piston raises from a bottom dead center and a piston groove | channel communicates with an air port, (II) further raises a piston. The state where the piston groove communicated with the air port is communicated with the gas vent port, and (III) shows the state where the piston is further raised and the piston groove communicates with the scavenging port. It is a figure which shows an example of a piston groove in order to demonstrate the setting of the height dimension of the piston groove included in this invention. It is a figure which shows the other example of a piston groove in order to demonstrate the setting of the height dimension of the piston groove included in this invention. It is a figure for demonstrating the other structure and effect | action included in invention, (I) shows the state which the piston began to raise from a bottom dead center, (II) is just before a piston groove | channel communicates with an air port. (III) shows the state where the piston is further raised and the piston groove communicated with the air port is communicated with the gas vent port. (IV) shows the state where the piston is further raised and the piston groove becomes the scavenging port. Indicates the state of communication. It is a perspective view of the piston contained in the air lead type stratified scavenging two-cycle internal combustion engine of an example. It is a figure for demonstrating the structure of the cylinder contained in the air lead type stratified scavenging type 2 cycle internal combustion engine of an Example. It is the cross-sectional view which cut | disconnected the air lead type stratified scavenging type 2 cycle internal combustion engine of the Example at the height level of the exhaust passage. It is a figure for demonstrating the structure of the cylinder contained in the air lead type stratified scavenging 2 cycle internal combustion engine of the modification. It is a figure for demonstrating the state in the piston raising process of the two-cycle engine of the Example containing the piston provided with the piston groove with comparatively large up-and-down width, (I) is located in a bottom dead center (II) shows the state where the piston has risen from the bottom dead center, (III) shows the state where the piston is further raised and the piston groove communicates with the air port, and (IV) shows the state where the piston is further Shows a state where the piston groove is in communication with the vent port, and (V) shows a state when the piston is located at the top dead center. It is a figure for demonstrating the state in the piston raising process of the two-cycle engine of the Example containing the piston provided with the piston groove with comparatively small up-and-down width, (I) is located in a bottom dead center (II) shows the state where the piston has risen from bottom dead center, (III) shows the state immediately after the piston has further moved up and the piston groove communicated with the air port, and (IV) shows Further, the piston rises and the piston groove communicates with the gas vent port, and (V) shows the state when the piston is located at the top dead center. It is a perspective view of the piston contained in the air lead type stratified scavenging two-cycle internal combustion engine of the modification. FIG. 12 is a front view of a piston groove of the piston illustrated in FIG. 11. FIG. 12 is a cross-sectional view of the engine including the piston illustrated in FIG. 11 cut at a height level of the exhaust passage. It is a figure for demonstrating the state in the piston raising process of the conventional 2 cycle engine, (I) shows the state just before a piston groove | channel communicates with an air port, (II) shows that a piston raises, The state where the piston groove communicates with the air port is shown, and (III) shows the state where the piston further rises and the piston groove communicated with the air port communicates with the scavenging port.

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

  FIG. 5 shows a piston included in the air-leading stratified scavenging two-cycle internal combustion engine of the embodiment. Referring to FIG. 5, piston 20 has a piston groove 22 on its peripheral surface. The piston 20 has a piston pin hole 24 and is connected to a connecting rod (not shown) by a piston pin (not shown) inserted into the piston pin hole 24.

  The piston 20 is fitted to a cylinder 26 shown in FIG. The cylinder 26 has first and second scavenging passages 30 and 32 on the left and right when viewed in plan, and the first and second scavenging passages 30 and 32 communicate with the crank chamber 34. First and second scavenging ports 30 a and 32 a are opened in the cylinder wall 28. The first scavenging port 30 a communicates with the first scavenging passage 30. The second scavenging port 32 a communicates with the second scavenging passage 32. That is, the engine of the embodiment is a scavenging four-flow engine.

  In the figure, reference numeral 36 indicates an exhaust passage. Reference numeral 38 indicates an air passage, and 38a indicates an air port. Reference numeral 40 indicates an air-fuel mixture passage. Air is supplied to the air passage 38. The air-fuel mixture passage 40 is supplied with the air-fuel mixture generated by a carburetor (not shown), and the air-fuel mixture is supplied to the crank chamber 34. Reference numeral 42 indicates a spark plug.

  With continued reference to FIG. 6, a gas vent port 46 is formed in the cylinder wall 28 as an additional port. The gas vent port 46 communicates with the crank chamber 34 via the first scavenging passage 30.

  FIG. 7 is a cross-sectional view of the air-leading stratified scavenging two-cycle internal combustion engine 50 of the embodiment. Referring to FIG. 7, the first scavenging port 30 a and the second scavenging port 32 a positioned on the left and right are directed in the direction opposite to the exhaust passage 36. In other words, the two-cycle engine 50 of the embodiment is a reverse scavenging engine. FIG. 7 shows a state in which the piston groove 22 communicates with the first and second scavenging ports 30a and 32a. In this state, air is supplied to the first and second scavenging passages 30 and 32 through the piston groove 22.

  FIG. 8 shows a cylinder 52 which is a modification of the cylinder 26 shown in FIG. The cylinder 52 also has first and second scavenging passages 30 and 32, and the first and second scavenging ports 30 a and 32 a are open to the cylinder wall 54. A gas vent port 46 is opened in the cylinder wall 54. The gas vent port 46 communicates with the crank chamber 34 through a gas vent passage 56 independent of the first and second scavenging passages 30 and 32.

  The piston groove 22 extends in the circumferential direction of the piston 20. And the gas vent port 46 is arrange | positioned in the position adjacent to the 1st scavenging port 30a located in the exhaust port side.

  FIGS. 9 and 10 show the first and second scavenging passages 30 and 32 through the piston groove 22 in the process of raising the piston (only the first and second scavenging ports 30a and 32a are shown in FIGS. 9 and 10). A specific example of supplying air will be described. The engine 50A illustrated in FIG. 9 has a configuration that is expanded upward as a method of expanding the volume of the piston groove 22. In the engine 50B shown in FIG. 10, the position where the piston groove 22 is formed is arranged below the piston pin hole 24 (FIG. 5). The vertical width of the piston groove 22 is smaller than the piston groove 22 shown in FIG.

  The engine 50A of FIG. 9 will be described in which the piston groove 22 has a relatively large vertical width. FIG. 9I shows the piston 20 located at the bottom dead center. When the piston 20 rises from the bottom dead center ((II) in FIG. 9), the crank chamber 34 becomes negative pressure. Even if the piston 20 is further raised and the piston groove 22 communicates with the air port 38a, the gas inside the piston groove 22 does not flow until it communicates with the gas vent port 46 ((III) in FIG. 9).

  When the piston 20 further rises and the piston groove 22 communicating with the air port 38a communicates with the gas vent port 46, the gas in the piston groove 22 is drawn into the crank chamber 34 via the gas vent port 46, Following this, air is drawn into the piston groove 22 from the air port 38a ((IV) in FIG. 9). That is, a gas flow is generated inside the piston groove 22.

When the piston 20 further rises and reaches top dead center, the first and second scavenging ports 30a and 32a are in communication with the piston groove 22, while the gas vent port 46 is closed by the piston 20. It will be in a state ((V) of FIG. 9). As a modification, the gas vent port 46 may open to the crank chamber 34 when the piston 20 is located at the top dead center.

  When a gas flow is generated inside the piston groove 22 in the state of (IV) in FIG. 9, the first and second scavenging ports 30a immediately after that until the state of FIG. 9 (V) (top dead center). , 32a communicates with the piston groove 22 so that air enters the first and second scavenging ports 30a, 32a. Therefore, it is ensured that air is drawn from the air passage 38 through the air port 38a into the piston groove 22, and this air is charged into the first and second scavenging passages 30, 32 from the first and second scavenging ports 30a, 32a. Can increase the sex.

  The engine 50B of FIG. 10 in which the vertical width of the piston groove 22 is relatively small will be described. FIG. 10 (I) shows the piston 20 located at the bottom dead center. When the piston 20 rises from the bottom dead center, the crank chamber 34 becomes negative pressure, but the gas in the piston groove 22 does not flow until the piston 20 further rises and the piston groove 22 communicates with the gas vent port 46 (FIG. 10). (II), (III)).

  When the piston 20 further rises and the piston groove 22 communicates with the gas vent port 46, the negative pressure in the crank chamber 34 acts on the piston groove 22, and the gas in the piston groove 22 passes through the gas vent port 46 and the first scavenging passage 30. Sucked into. The air in the air passage 38 is drawn into the piston groove 22 through the air port 38a. That is, at the same time as the piston groove 22 communicates with the gas vent port 46, a gas flow is generated inside the piston groove 22.

  When the piston 20 further rises and reaches top dead center, the first and second scavenging ports 30a and 32a are in communication with the piston groove 22, while the gas vent port 46 is closed by the piston 20. ((V) in FIG. 10). When the flow of gas is generated in the piston groove 22 in the state of (IV) in FIG. 10, the first and second scavenging ports 30a and 32a are connected to the piston groove immediately after that until the state of (V) in FIG. A state is created in which air enters the first and second scavenging ports 30a and 32a in communication with the air. Therefore, it is ensured that air is drawn from the air passage 38 through the air port 38a into the piston groove 22, and this air is charged into the first and second scavenging passages 30, 32 from the first and second scavenging ports 30a, 32a. Can increase the sex.

  11 to 13 are diagrams related to the above-described engine modification. The modification shown in FIGS. 11 to 13 is related to FIG. 4 described above. In the piston 20 included in the engine shown in FIGS. 11 to 13, a pressure transmission through hole 60 is formed in the piston groove 22, and the pressure transmission through hole 60 is always in communication with the crank chamber 34. The pressure transmission through hole 60 illustrated in FIGS. 11 to 13 corresponds to the pressure transmission through hole 12 described with reference to FIG. 4.

The pressure transmission through hole 60 may be disposed at any location of the piston groove 22. According to experiments, it has been found that it is effective to dispose the piston groove 22 on the downstream side. Referring to FIG. 12, the alternate long and short dash line is a vertical line VL that passes through piston pin hole 24. Placing the pressure transmission through hole 60 on the downstream side (left side in FIG. 12) of the perpendicular line VL passing through the piston pin hole 24 is effective in generating a preferable gas flow in the piston groove 22. . That is, the pressure transmission through hole 60 is preferably disposed at a position adjacent to the first scavenging port 30a located on the exhaust port side.

  The pressure transmission through hole 60 may have a diameter of 0.1 mm to 3.0 mm, preferably a diameter of 0.5 mm to 2.5 mm, and most preferably a diameter of 1.0 mm to 2.0 mm. In the embodiment, the pressure transmission through hole 60 is disposed at the downstream end in the gas flow direction of the piston groove 22, that is, the left end (end on the exhaust port side) in FIG. 12, and when the piston groove 22 is viewed from the front. It is positioned on the lower side (crank chamber side).

  According to the engine of the embodiment, the certainty of filling the scavenging passage with air can be improved. This means that it can contribute to optimizing the timing at which the piston groove and the scavenging port communicate with each other and the timing at which the piston groove and the air port communicate with each other. As a result, the output can be increased while improving the emission characteristics of the exhaust gas of the air-leading stratified scavenging two-cycle internal combustion engine.

  In the embodiment, as an example, an engine in which two scavenging ports 30a and 32a are provided on one side and the two scavenging ports 30a and 32a on each side are symmetrically arranged has been described as an example. Needless to say, it is not limited to. The present invention includes, for example, the following modifications.

(1) An engine having one scavenging port on one side.
(2) An engine in which one or more scavenging ports on each side are arranged asymmetrically.
(3) In the embodiment, each of the plurality of scavenging ports 30a and 32a includes the independent scavenging passages 30 and 32 on one side, and this is an engine constituted by one scavenging passage extending in a Y shape, for example.

  The present invention can be applied to an air lead type stratified scavenging two-cycle internal combustion engine. The present invention is preferably applied to a single-cylinder air-cooled engine mounted on a portable work machine such as a brush cutter or a chain saw.

20 piston 22 piston groove 24 piston pin hole VL perpendicular passing through the piston pin hole 26 cylinder 28 cylinder wall 30 first scavenging passage 30a first scavenging port 32 second scavenging passage 32a second scavenging port 34 crank chamber 36 exhaust passage 38 air passage 38a Air port 46 Gas vent port 12, 60 Pressure transmission through hole

Claims (5)

An air port (4a) that opens in the cylinder wall (2) and is opened and closed by a piston;
Wherein a cylinder wall scavenging passage having a scavenging port opened and closed by the opening and and the piston (2) (6a) (6), and scavenging passage communicating with the crank chamber (6),
A piston groove (8) formed on the peripheral surface of the piston and capable of communicating the air port (4a) and the scavenging port (6a) ;
A gas venting port (10) that opens to the cylinder wall (2) independently of the scavenging port (6a) and is opened and closed by the piston, and is smaller than the scavenging port (6a), the piston groove ( 8) supplying the air from the air port (4a) to the scavenging port (6a) through 8) , and having a gas vent port (10) constantly communicating with the crank chamber in order to strengthen the initial movement of the air flow ,
The venting port (10) communicates with the scavenging passageway (6);
The gas vent port (10) is located on the crank chamber side which is lower than the scavenging port (6a) ,
In the process of raising the piston , the piston groove (8) communicates with the gas vent port (10) in the process of moving the piston from bottom dead center to top dead center, and then communicates with the scavenging port (6a). in the process of the prior said piston groove in communication with the air port (4a) to (8) is communicated with the scavenging port (6a), a piston groove in communication with said air ports (4a) (8) the gas vent communicated with port (10) strengthened initial of the air flows,
When the piston is at the top dead center, the piston groove (8) is not in communication with the air port (4a) . The air-leading laminar scavenging according to claim 1, wherein the venting port (10) is disposed at a position communicating with the end of the piston groove (8) opposite to the air port (4a). Formula 2 cycle internal combustion engine. The piston groove (8) has a height dimension that allows simultaneous communication with the scavenging port (6a) and the degassing port (10) in communication with the air port (4a). Or an air-driven stratified scavenging two-cycle internal combustion engine according to 2; A plurality of the scavenging ports (6a) are arranged on one side of the engine,
Among the plurality of scavenging ports (6a), said venting port at a position adjacent to the farthest scavenging port from said air ports (4a) is arranged, according to any one of claims 1 to 3 The air-leading stratified scavenging two-cycle internal combustion engine. The air-leaded stratified scavenging two-cycle internal combustion engine according to any one of claims 1 to 4 , wherein the piston groove includes a pressure transmission through hole (60) communicating with the crank chamber.

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