CN216008688U

CN216008688U - Two-stroke engine

Info

Publication number: CN216008688U
Application number: CN202120523094.6U
Authority: CN
Inventors: 陈阳; 陈春明; 陈欣; 金松; 朱瑞松
Original assignee: Shandong Pufeng Garden Technology Co ltd
Current assignee: Shandong Pufeng Garden Technology Co ltd
Priority date: 2021-03-12
Filing date: 2021-03-12
Publication date: 2022-03-11
Anticipated expiration: 2031-03-12

Abstract

The present invention relates to the field of engine technology, and discloses a two-stroke engine, a general two-stroke engine is configured to introduce fresh mixed gas into a combustion chamber in a scavenging stroke to extract heat from the inside of the combustion chamber and directly sweep the outside of a cylinder without passing through the combustion stroke, such blow-by gas (short-cut gas) helps to lower the temperature of the combustion chamber of the cylinder and lower the temperature of a piston, but a large amount of blow-by gas directly causes degradation of exhaust gas, and therefore, in order to reduce the blow-by gas, a simplified two-stroke engine is configured such that the smaller the amount of blow-by gas, the higher the temperature of the combustion chamber, the higher the temperature of the piston, and the two-cycle engine with reduced exhaust gas fails to prevent abnormal combustion and running-in due to the increased temperatures of the combustion chamber and the piston, and an air-cooled engine is designed to increase the area of air-cooling fins of the cylinder, increase the size of an air-cooled fan, to increase the amount of cooling air.

Description

Two-stroke engine

Technical Field

The utility model relates to the technical field of engines, in particular to a two-stroke engine,

background

A general two-stroke engine is configured such that fresh air-fuel mixture is introduced into a combustion chamber in a scavenging stroke to extract heat from the inside of the combustion chamber and directly sweeps the outside of a cylinder without passing through the combustion stroke, such blow-by gas (short-cut gas) contributes to lowering the temperature of the combustion chamber of the cylinder and lowering the temperature of a piston, but a large amount of blow-by gas directly causes degradation of exhaust gas, and therefore, in order to reduce the blow-by gas, a simplified two-stroke engine is configured such that the smaller the amount of blow-by gas, the higher the temperature of the combustion chamber and the higher the temperature of the piston.

For this reason, the two-cycle engine in which the exhaust gas is reduced due to the temperature rise of the combustion chamber and the piston fails to prevent the occurrence of abnormal combustion and running-in, and an air-cooled engine is designed to increase the area of the air-cooling fins of the cylinder and to increase the size of the air-cooling fan to increase the amount of cooling air, but even if a larger amount of cooling air is supplied to the air-cooling fins, such cooling is not effective in reducing the temperature inside the cylinder, such as the combustion chamber and the piston.

SUMMERY OF THE UTILITY MODEL

The present invention is directed to a two-stroke engine that solves the problems set forth above in the background.

In order to achieve the purpose, the utility model provides the following technical scheme: a two-stroke engine comprising an engine and a cylinder having a cylindrical hole portion and a combustion chamber continuously connected to one side of the hole portion in an axial direction, the cylinder being provided with an opening opened in a cylinder bore surface, the opening being configured as a snap-fit passage communicating the hole portion and a crank chamber, and a communication passage to the opening, the opening being opened in a cylinder block surface, the opening being located in a hole surface of the other side, configured to communicate the hole portion and a scavenging passage with each other, wherein a second opening is located at a position corresponding to a through-hole of a piston in a circumferential direction of the hole portion, the cylinder and the piston being configured such that the through-hole overlaps the second passage at least for an interval of a scavenging stroke to communicate with the passage, the opening being opened in the hole surface of the piston side, the scavenging passage communicating with an internal space of the piston through the through-hole and the communication passage, the scavenging passage comprises a suction side scavenging passage which is arranged far away from each other in the circumferential direction of a suction port part, the top of the circumferential direction of the suction port part is provided with an exhaust side scavenging passage, the opening is arranged at the position corresponding to the through hole of the piston in the circumferential direction of the hole part, one side of the piston is provided with a crown, the outer side of the piston crown is sleeved with a piston ring, the piston ring is embedded in a groove formed in the surface of the piston, one side of the piston is provided with a concave part, the top of the cylinder is provided with a bore part, and one end of the other side of the communication passage A is directly connected to the central part of the passage.

Preferably, the axial length of the second opening of the communication channel is greater than that of the through hole, a guide portion a is formed in the surface of the combustion chamber, and a spark plug is mounted on one side of the top of the combustion chamber.

Preferably, the two sides of the engine are symmetrically provided with scavenging boxes b, the top of the engine is provided with a cylinder body a, the inside of the cylinder is symmetrically provided with exhaust side scavenging ports, the exhaust side scavenging ports are adjacently provided with suction side scavenging ports, and one end of the other side of the channel is connected with the end part of the crank chamber a side.

Preferably, a crank chamber is opened in the cylinder, the cylinder has an intake port configured to communicate with the crank chamber a through the cylinder hole portion, the cylinder hole portion communicates with and is oppositely provided with an exhaust port, and the passage communicates the hole section and the intake-side scavenging passage with each other.

Preferably, the internally mounted of engine has crank mechanism, the axle that revolves is installed to crank mechanism's one end, crank mechanism keeps away from the one end of revolving the axle and is provided with the crank pin, crank mechanism's internal connection has the connecting rod.

Preferably, the cylinder comprises a crank chamber a, a combustion chamber, a bore section, a circumferential side wall and an opening, the outer side of the piston is provided with a circumferential wall portion, the opening of the circumferential wall portion is fluidly coupled with the crank chamber a, and the bottom of the opening is provided with a lower end a.

Preferably, a communication channel B is formed in the inner side of the bore, the communication channel B is fluidly connected with the scavenging channel at one side of the end of the scavenging channel, and the crank channel is adjacent to the opening of the crankcase.

Preferably, the communication passage opens in a central portion of the scavenging passage, and the communication passage is fluidly connected to the scavenging passage at a position between the end portions of the scavenging passage.

Preferably, the side scavenging passage has an opening opened at a side adjacent to the hole portion, and the exhaust side scavenging passage is configured such that the opening is fluidly coupled with the hole portion through the crank chamber.

Compared with the prior art, the utility model provides a two-stroke engine which has the following beneficial effects:

the two-stroke engine, without lowering the intake efficiency by maintaining the effect of reducing the blow-by gas of a pair of intake-side scavenging passages for introducing fresh mixture gas and a pair of exhaust-side scavenging passages for introducing EGR gas, and therefore without causing a decrease in the exhaust performance, the cooling of the crown portion of the piston prevents the occurrence of abnormal combustion and running-in, the intake rate is a value obtained by dividing the weight of the introduced fuel by the weight of the combustion chamber,

drawings

FIG. 1 is a vertical cross-sectional view of a two-stroke engine of the present invention;

FIG. 2 is a cross-sectional view of the present invention taken along line II-II of FIG. 1;

FIG. 3 is a schematic view of the two-sided structure of the piston of the present invention;

FIG.4 is a cross-sectional view of the cylinder of the present invention;

fig. 5A and 5B are longitudinal sectional views of the two-stroke engine according to the first embodiment, where fig. 5A is a view showing a state where a piston is positioned at a top dead center, and fig. 5B is a view showing a state where the piston is positioned at a bottom dead center;

fig. 6A to 6D are sectional views of the two-stroke engine of the first embodiment taken along line a-a in fig. 1, and fig. 2 is a view showing a state of reciprocation of the piston;

fig. 7 is a longitudinal sectional view of a cylinder of the two-stroke engine of the second embodiment;

fig. 8A and 8B are longitudinal sectional views of a two-stroke engine according to a second embodiment, fig. 8A being a view showing a state in which a piston is positioned at a top dead center, and fig. 8B being a view showing a state in which the piston is positioned at a bottom dead center;

fig. 9A to 9D are sectional views of a two-stroke engine of a second embodiment taken along line a-a of fig. 8, and fig. 2 is a view showing a state of reciprocation of a piston;

FIG. 10 is a vertical cross-sectional view of a cylinder of a two-stroke engine according to a third embodiment;

fig. 11A and 11B are longitudinal sectional views of a two-stroke engine according to a third embodiment, fig. 11A being a view showing a state in which a piston is positioned at a top dead center, and fig. 11B being a view showing a state in which the piston is positioned at a bottom dead center;

fig. 12A to 12D are cross-sectional views of a two-stroke engine of a third embodiment taken along line a-a in fig. 11, and fig. 2 is a view showing a state of reciprocating motion of a piston.

In the figure: 1. an engine; 11. a combustion chamber; 12. an air suction port; 13. an exhaust port; 14. a suction side scavenging passage; 14a, a guide part; 16. an exhaust-side scavenging passage; 18. a spark plug; 2. A cylinder; 2b, a scavenging box; 2a, a cylinder body; 21. an exhaust side scavenging port; 22. a suction side scavenging port; 3. a bore portion; 30. a crown portion; 31. a peripheral wall portion; 32. a piston ring; 33. a groove; 34. a recess; 36. a through hole; 4.a piston; 401. a communication channel A; 40a, lower end; 402. A communication passage B; 41. an opening; 6. a crankcase; 6a, a crank chamber; 7. a crankshaft mechanism; 8. rotating the shaft; 9. a crank pin; 10. a connecting rod.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the protection scope of the present invention,

referring to fig. 1 to 12, based on the case where the cylinder main body 2a is disposed upright such that the bore portion 3 of the cylinder 2 extends in the vertical direction with the opening of the piston 4 to be inserted thereinto facing downward, "up and down" is used in the following description, the "upper side" corresponding to the upper side in the direction of the axis L of the bore portion 3, and the "lower side" corresponding to the lower side in the direction of the bore L3.

As shown in fig. 1 and 2, an engine (two-stroke engine) 1 is a two-stroke engine employing a scherrer system as a scavenging method, and is mounted on, for example, a lawn mower, a backpack-type power sprayer, or the like, the engine 1 having a cylinder 2, a piston 4 reciprocating in a bore portion 3 of the cylinder 2, a crankcase 6 connected to a lower side of the cylinder 2, and a crank mechanism 7 disposed in a crank chamber 6a of the crankcase 6, a crank in fig. 8 disposed in the piston 4 and a crank pin 9 of the crank mechanism 7 disposed in the crankcase 6 being connected by a connecting rod 10, the piston 4 being disposed in a hole portion 3 so as to be reciprocatable in a direction of an axis L, a combustion chamber 11 formed in the cylinder 2 between the combustion chamber 11 and a chamber 6a between the crank, a cylindrical hole portion 3 continuously connected to the combustion chamber 11 and configured for inserting the piston 4 therein, a suction port 12 (see fig. 4) and an exhaust port 13 configured to communicate with the hole portion 3, a pair of suction-side scavenging passages 14,14 and a pair of exhaust-side scavenging passages 16, the cylinder 2 having a cylinder body 2a and scavenging cassettes 2b, 2b mounted on a lower portion of the cylinder body 2a, the scavenging cassettes 2b, 2b being fitted in two openings formed to oppose each other in the radial direction of the hole portion 3 and fixed thereto, the pair of suction-side scavenging passages 14,14 and the pair of exhaust-side scavenging passages 16, 16 being formed by the cylinder body 2a and the scavenging cassettes 2b, 2 b.

The hole portion 3 has a cylindrical hole surface 3a and extends in the direction of the axis L in the cylinder 2, the hole portion 3 is open on the bottom dead center side (lower side in fig. 1) to communicate with the crankcase 6a, a concave combustion chamber 11 is formed at the end portion on the top dead center side of the hole portion 3, a discharge electrode such as an ignition plug 18 is arranged inside the combustion chamber 11, an ignition plug mounting hole is provided in the combustion chamber 11, an intake port 12 and an exhaust port 13 are configured to communicate with the hole portion 3, and the exhaust port 13 is located slightly closer to the top dead center than the top dead center in the direction of the axis L, the intake port 12 and the intake port 12 are offset from each other by about 180 ° in the circumferential direction of the hole portion 3 so as to be opposed to each other in the radial direction of the hole portion 3, the intake port 12 and the exhaust port 13 are configured to communicate with the hole portion 3, and the exhaust port 13 is located closer to the top dead center than the intake port 12 in the direction of the axis L, the intake port 12 and the exhaust port hole 13 are arranged offset from each other by approximately 180 degrees in the circumferential direction of the hole portion 3 so as to be opposed to each other in the radial direction of the hole portion 3, intake-side scavenging passages 14,14 are provided for introducing a fresh mixed gas (working gas) containing fuel, which is a fuel-air mixture for operating the engine composed of a mixture of air and gasoline as fuel, into the cylinder bore portion 3 and the combustion chamber 11 in a scavenging stroke and extending in the direction of the axis L inside the side wall of the cylinder 2, the ends of the intake-side scavenging passages 14,14 on the top dead center side are respectively configured to substantially communicate with the intake port device 113, as shown in fig. 2, the ends of the intake-side scavenging passages 14,14 on the top dead center side are located at the same position as the exhaust port 13 in the direction of the axis L, and the hole 3 is an intake-side scavenging port (first opening) 21, 21, intake-side scavenging passages 14,14 are arranged away from each other in the circumferential direction of the hole portion 3, the intake passages 14,14 are arranged substantially line-symmetrically in the radial direction with respect to the first intake port 12 and the exhaust port 13, the intake-side scavenging passages 14,14 are provided to guide fresh mixture gas introduced into the intake port, the end portions of the intake-side scavenging passages 14,14 on the bottom dead center side communicate with the above-mentioned crank chamber 6a, exhaust-side scavenging passages 16, 16 are provided to introduce EGR gas (non-working gas) after combustion into the exhaust port 3 and the combustion chamber 11 with a lower fuel content than the working gas in a scavenging stroke and extend in that direction, the end portions of the exhaust-side scavenging passages 16, 16 on the top dead center side are respectively configured to communicate with the hole portion 3 at substantially the same position as the exhaust port 13 in the direction of the exhaust port 13, the exhaust-side scavenging passage 16, which opens on the hole portion 3, The end portions on the top dead center side of the intake port 16 are defined as exhaust-side scavenging ports (first openings) 22, 22, the exhaust-side scavenging passages 16, 16 are arranged away from each other in the circumferential direction of the hole portion 3, more specifically, the exhaust-side scavenging passages 16, 16 are arranged substantially line-symmetrically with respect to an imaginary line, connecting the intake port 12 and the exhaust port 13 in the radial direction, the exhaust-side scavenging passages 16, 16 being provided to guide the EGR gas introduced into the holes to communicate with the above-described crank chamber 6a on the bottom dead center side of the exhaust-side scavenging passages 16, 16.

In order to perform stratified scavenging, the direction and shape of the intake-

side scavenging passages

14,14 and the exhaust-

side scavenging passages

16, 16 are accurately determined, the intake-

side scavenging passages

14,14 and the exhaust-

side scavenging passages

16, 16 have scavenging passages as scavenging passages where a guide 14a (see fig. 4) for guiding fresh mixture gas to a predetermined introduction direction is provided, each end portion on the top dead center side of the intake-

side scavenging passages

14,14 is provided with a guide 16a (see fig. 4) for guiding EGR gas to a predetermined introduction direction on each end portion on the top dead center side, and the side surfaces of the exhaust-

side scavenging passages

16, 16.

The piston 4 will be described with reference to fig. 3, the piston 4 having a cylindrical crown portion 30 constituting the top of the piston 4 and a cylindrical peripheral wall portion 31 provided continuously from the periphery of the crown portion 30, two piston rings 32 (refer to fig. 1), the bore portion 3 being fixed to the outer periphery of the crown portion 30 in order to maintain airtightness within the combustion chamber 11, the piston rings 32 being installed in the grooves 33, the piston 4 being arranged to reciprocate in the bore portion 3, the crown portion 30 being opposed to the combustion chamber 11, and the peripheral wall portion 31 extending along the bore surface 3a of the bore portion 3.

A groove-like recess 34 extending in the range from the exhaust port 13 to the exhaust-side scavenging port 22 at the outer periphery of the peripheral wall portion 31 is formed at the lower end of the peripheral wall portion 31, each recess 34 constituting the exhaust port 13 and the exhaust port 13, the exhaust-side scavenging passages 16 communicating with each other when the piston 4 is positioned near the top dead center, each recess 34 communicating the exhaust port 13 with the exhaust-side scavenging passage 16 when the piston 4 is positioned near the top dead center, so that the burned exhaust gas enters the exhaust-side scavenging port from the exhaust port 13 as EGR gas, that is, the upper portion of the exhaust-side scavenging port 16 can be filled with EGR gas and a fresh mixed gas can be filled under the EGR gas, and when scavenging is performed while the piston 4 is lowered, the EGR gas flows into the cylinder 2 first and then the fresh mixed gas flows into the cylinder 2, which makes it possible to perform so-called stratified scavenging in the engine 1, in the upper portion of the peripheral wall portion 31 of the piston 4, at a position corresponding to the intake-side scavenging passage 14, two through holes 36 are provided in the circumferential direction of the bore section 3, the through holes 36 penetrate the peripheral wall portion 31 in the radial direction of the peripheral wall portion 31, for example, the through holes 36 are rectangular in shape, for example, the through holes 36 are widened in the upper portion thereof (on the combustion chamber 11 side) and narrowed in the lower portion thereof (on the crank chamber 6a side), the through holes 36 are located below the two piston rings 32, that is, the through holes 36 communicate the outer space of the piston 4 with the inner space of the piston 4, and the piston 4 is also a space on the back of the boss portion 30.

The branch flow passage of the fresh mixed gas will be described with reference to fig.4.as shown in fig.4, the cylinder 2 is provided below the suction-side scavenging port 21 of the suction-side scavenging passage 14 with a groove-like communication passage 40, the communication passage 40 opening to the hole portion 3, having a predetermined width while being oriented in the direction of the axis L, the communication passage a401 having a circumferential width smaller than that of the suction-side scavenging opening 21 and larger than that of the through-hole 36, the communication passage a401 having a rectangular opening (second opening) 41, the rectangular opening 41 opening to the second opening 41, the end position on the suction port 12 side of the opening 41 coinciding in the circumferential direction with the end position on the suction port 12 side of the suction-side scavenging port 21, the end side on the exhaust port 13 side of the opening 41 being located slightly closer to the suction port 12 side than the end side on the exhaust port 13 side of the suction-side scavenging port 21, the upper end of the communication passage 40 terminating within this range, the height is the position where the suction port is located, 12 are provided, the lower end 40a of the communication passage 40 opens and expands at the lower end of the cylinder body 2a, and communicates with the crank chamber 6a and the lower end of the suction-side scavenging passage 14 (the end portion on the crank chamber 6a side), in other words, the communication passage a401 communicates with the lower side only at the lower end of the suction-side scavenging passage 14, in such a manner that the communication passage a401 communicates with the hole portion 3 and the suction-side scavenging passage 14.

As shown in fig. 5A and 5B and fig. 6A to 6D, the opening 41 is longer in the direction of the axis L than the through hole 36 of the piston 4, and as described above, the cylinder body 2a having the communication passage 40 can be molded by a well-known molding method.

First, the intake-side scavenging port 21, the exhaust-side scavenging port 22, and the exhaust port 13 are closed by the piston 4 in accordance with the upward movement of the piston 4 from the bottom dead center to the top dead center, so that the fresh mixture gas in the combustion chamber 11 is compressed, and the intake port 12 communicates with the crank chamber 6a through the hole portion 3 in accordance with the further ascent of the piston 4, thereby introducing the fresh mixture gas into the crank chamber 6a (see fig. 5A and 6D).

When the piston 4 reaches the vicinity of the top dead center, the mixture explodes in the combustion chamber 11 to lower the piston 4 toward the bottom dead center, and when the piston 4 is positioned in the vicinity of the top dead center, the exhaust port 13 and the exhaust-side engagement opening 22 communicate with each other through the recess 34 of the piston 4 (see fig. 5A), and the exhaust gas after one cycle of combustion is filled into the exhaust-side scavenging port 16 as the EGR gas.

As the piston further descends, the exhaust port 13 becomes an open state to discharge combustion gas (see fig. 6A), then, after a slight delay from the opening time of the exhaust port 13, exhaust is started from the upper edge of the intake-side exhaust device, the engagement opening 21 and the exhaust-side scavenging opening 22 are exposed in the hole portion 3 to start a scavenging stroke, at which time the interior of the exhaust-side scavenging passage 16 is filled with EGR gas and the interior of the intake-side scavenging passage 14 is filled with fresh mixed gas, and next, the exhaust-side scavenging port 22 is opened, so that EGR gas is introduced into the hole portion 3 by pressure.

As the piston descends further, the exhaust port 13 becomes open to exhaust the combustion gas (see fig. 6A), then, after a slight delay from the opening time of the exhaust port 13, the upper edge of the intake-side exhaust device is exposed in the hole portion 3 at the engagement opening 21 and the exhaust-side scavenging opening 22, to start the scavenging stroke, at this time, the interior of the exhaust-side scavenging passage 16 is filled with the EGR gas, and the interior of the suction-side scavenging passage 14 is filled with fresh mixed gas, and, next, the exhaust-side scavenging port 22 is opened, so that EGR gas is introduced into the chamber 3 by the pressure difference between the combustion chamber 11 and the chamber 3 and the exhaust-side scavenging passage 16, the opening 21 becomes open, and fresh mixed gas is introduced into the hole portion 3 by the pressure difference between the combustion chamber 11 and the hole portion 3 and the suction side scavenging passage 14 (see fig. 6B).

When the intake-side scavenging opening 21 of each intake-side scavenging passage 14 is opened to the bore section 3, fresh mixed gas starts to enter the bore section 3 from the main flow of the intake-side scavenging passage 14 to start a scavenging stroke (see fig. 6B), and as the piston 4 descends, the fresh mixed gas flows into the bore section 3 from the intake-side scavenging opening 21 through the intake-side scavenging passage 14, while at the same time, each exhaust-side scavenging passage 16 is opened, whereby EGR gas and fresh mixed gas enter the chamber 3 in sequence from the intake-side scavenging port 22, which achieves so-called stratified scavenging.

At this time, each through hole 36 of the piston 4 disposed below the piston ring 32 overlaps with the opening 41 provided in the cylinder 2, so that the through hole 36 communicates with the communication passage a401, thereby forming a branch flow of fresh mixed gas whose communication timing is different from the scavenging timing that is indispensable for the performance requirements of the engine 1, so as to merge into the lower end 14 of the intake-side scavenging passage, i.e., the through hole 36 and the communication passage a401 can be made to communicate with each other at an arbitrary timing determined by the position of the through hole 36.

Next, since the pressure difference between the intake-side scavenging passage 14 and the communication passage 40 increases as the main flow of the fresh mixed gas starts to flow while the intake-side scavenging opening 21 is opened to the hole portion 3, a movement of the fresh mixed gas is formed at the lower end of the intake-side scavenging passage 14 of the main flow in the branch flow formed from the through hole 36 and the communication passage a401 (fig. 6C), at which time the fresh mixed gas inside the piston 4, that is, the fresh mixed gas remaining in the piston 4 moves on the back surface of the crown portion 30 and is combined therewith, to replace the fresh mixed gas with another gas to cool the crown portion 30.

In the engine 1, the effect of lowering the temperature is achieved in the interior of the cylinder 2, the interior of the cylinder 2 is difficult to be cooled by air blowing from the outside, and furthermore, since a part of the fresh air-fuel mixture absorbs heat from the crown portion, the fresh air-fuel mixture becomes easier to burn as it moves along the rear side of the crown portion 30 of the piston 30 before the hole portion 3 is introduced, so that evaporation of the fresh air-fuel mixture is promoted, and as the temperature of the fresh air-fuel mixture increases, the fresh air-fuel mixture becomes easier to burn, and when the fresh air-fuel mixture in the intake-side scavenging passage 14 of the main flow merges with the fresh air-fuel mixture in the communication passage a401 of the three-branch flow, the intake-side scavenging passage 14 increases while reducing the unburned gas component (THC) contained in the exhaust gas.

The amount of cooling air required for the cylinder 2 can be made smaller because the effect of the reduction of the temperature in the cylinder is combined with the reduction of the temperature of the piston 4, which means that the cooling fin area of the cylinder 2 is reduced, thereby reducing the weight of the cylinder and the diameter of the cooling fan, and consequently the weight of the engine 1.

Since the communication passage a401 to the opening 41 of the hole portion 3 is longer than the through hole 36 in the direction of the axis L and the opening 41 of the communication passage 40 is longer in the direction of the axis L, the communication state between the interiors can be maintained for a long time with the piston 4 and the piston of the intake-side scavenging passage 14 in the period in which the piston 4 moves near the bottom dead center, and therefore, in the case where the above-described pressure difference is generated, the cooling time of the flow of the fresh mixed gas can be made long, on the other hand, the through hole 36 of the peripheral wall portion 31 of the piston 4 only needs to have a certain length on the outer periphery of the piston 4, and by appropriately setting the size of the through hole 36, it is also possible to adjust the magnitude of the bypass scavenging flow rate.

Further, in the engine 1, the branch scavenging flow is a flow merged into the suction-side scavenging passage 14 through the through hole 36 and the communication passage 40 with respect to the main scavenging flow introduced from the crank chamber 6a toward the hole portion 3, and therefore, the fresh mixed gas merged from the communication passage a401 has little influence on the original scavenging direction determined by the suction-side scavenging passage 14, that is, the introduction direction into the hole section 3, and particularly, since the communication passage a401 is separated from the guide portion 14a at the lower end of the suction-side scavenging passage 14, the merging position of the branch scavenging flow is separated from the guide portion 14a, the guide portion 14a is an end portion on the side of the hole portion 3 for determining the introduction direction of the fresh mixed gas into the hole portion 3 (see fig. 6B and 6C), and therefore, the fresh mixed gas merged from the communication passage 40 does not influence the introduction direction of the fresh mixed gas into the hole portion 3, and further, since the lower end 40a of the communication passage 40 is opened at the lower end of the cylinder main body 2a, the mold can pull out the cylindrical body 2 downward when molding it, which does not cause a problem of requiring additional processing and complication of the mold, and facilitates molding.

As described above, the reduction effect of the blowby gas of the pair of intake-

side scavenging passages

14,14 for introducing the fresh mixture gas and the pair of exhaust-

side scavenging passages

16, 16 for introducing the EGR gas is maintained without lowering the intake efficiency, and therefore, without causing a decrease in the exhaust performance, the cooling of the crown portion 30 of the piston 4 prevents the occurrence of abnormal combustion and running-in, the intake rate is a value obtained by dividing the weight of the introduced fuel by the weight of the combustion chamber, the point in time in fig. 11 is the time when the exhaust port 13 is closed by supplying the weight of the fuel to the engine 1, and the operation refers to a phenomenon in which the engine is still operating even after the engine is closed to terminate the ignition of the spark plug.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A two-stroke engine comprising an engine (1) and a cylinder (2), characterized in that: the cylinder (2) having a cylindrical hole portion and a combustion chamber (11), the combustion chamber (11) being continuously connected to one side of the hole portion in an axial direction, the cylinder (2) being provided with an opening (41) opened in a cylinder bore surface, the opening (41) being configured as a snap-in passage that communicates a bore section and a crank chamber, and a communication passage A (401) to the opening (41), the opening (41) being opened in the cylinder bore surface, the opening (41) being located on the bore surface on the other side, configured to communicate the bore section and a scavenging passage with each other, wherein a second opening (41) is located at a position corresponding to a through hole (36) of the piston (4) in a circumferential direction of the hole portion, the cylinder (2) and the piston (4) being configured such that the through hole (36) overlaps with the second passage at least for an interval of the scavenging stroke to communicate with the passage, the opening (41) being opened in the bore surface on the piston (4) side, the scavenging passage communicates with the internal space of the piston (4) through a through hole (36) and a communication passage A (401), the scavenging passage includes an intake-side scavenging passage (14) provided apart from each other in the circumferential direction of the intake port (12), an exhaust side scavenging passage (16) is arranged at the top of the circumferential direction of the air suction port (12), the opening (41) is located at a position corresponding to the through hole (36) of the piston (4) in the circumferential direction of the hole portion, a crown part (30) is arranged on one side of the piston (4), a piston ring (32) is sleeved on the outer side of the crown part (30) of the piston (4), the piston ring (32) is embedded in a groove (33) formed on the surface of the piston (4), one side of the piston (4) is provided with a concave part (34), the top of the cylinder (2) is provided with a bore part (3), one end of the other side of the communication passage a (401) is directly connected to the central portion of the passage.

2. A two-stroke engine according to claim 1, wherein: the axial length of a second opening (41) of the communication channel A (401) is larger than that of the through hole (36), a guide part (14a) is formed in the surface of the combustion chamber (11), and a spark plug (18) is installed on one side of the top of the combustion chamber (11).

3. A two-stroke engine according to claim 1, wherein: the engine is characterized in that scavenging boxes (2b) are symmetrically arranged on two sides of the engine (1), a cylinder main body (2a) is arranged at the top of the engine (1), exhaust side scavenging ports (21) are symmetrically formed in the cylinder (2), air suction side scavenging ports (22) are adjacently formed in the exhaust side scavenging ports (21), and one end of the other side of the channel is connected to the end portion of the crank chamber (6 a).

4.A two-stroke engine according to claim 1, wherein: a crank chamber (6a) is opened in the cylinder (2), the cylinder (2) has an intake port (12) configured to communicate with the crank chamber (6a) through a cylinder bore portion, which communicates with each other and is oppositely provided with an exhaust port (13), which communicates a bore section and an intake-side scavenging passage (14) with each other.

5. A two-stroke engine according to claim 1, wherein: the internal mounting of engine (1) has crank mechanism (7), revolve axle (8) are installed to the one end of crank mechanism (7), the one end of revolving axle (8) is kept away from in crank mechanism (7) is provided with crank pin (9), the internal connection of crank mechanism (7) has connecting rod (10).

6. A two-stroke engine according to claim 1, wherein: the cylinder (2) comprises a crank chamber (6a), a combustion chamber (11), a bore section, a circumferential side wall and an opening (41), wherein a circumferential wall portion (31) is arranged on the outer side of the piston (4), the opening (41) of the circumferential wall portion (31) is in fluid coupling with the crank chamber (6a), and a lower end (40a) is arranged at the bottom of the opening (41).

7. A two-stroke engine according to claim 1, wherein: and a communication channel B (402) is formed in the inner side of the chamber part (3), and the communication channel B (402) is in fluid connection with the scavenging channel at one side of the end part of the scavenging channel.

8. A two-stroke engine according to claim 7, wherein: the communication passage B (402) opens in the central portion of the scavenging passage, and the communication passage B (402) is fluidly connected to the scavenging passage at a position between the ends of the scavenging passage.

9. A two-stroke engine according to claim 7, wherein: the exhaust side scavenging passage (16) is opened with an opening (41) at a side adjacent to the hole portion, and the exhaust side scavenging passage (16) is configured such that the opening (41) is fluidly coupled with the hole portion through a crank chamber (6 a).