阅读说明：本技术 一种小型汽油机用封闭式低排回流扫气通路气缸 (Closed low-exhaust backflow scavenging passage cylinder for small gasoline engine ) 是由 刘永根 杨慧明 刘运申 姜雪琨 秦义明 宋雄伟 于 2021-07-19 设计创作，主要内容包括：本发明公开了一种小型汽油机用封闭式低排回流扫气通路气缸,包括缸体,缸体内腔向上拱起形成燃烧室；缸体一侧缸壁下部设有进气口、另一侧缸壁设有排气口,进气口、排气口之间的缸体两侧缸壁分别设有扫气口,其中一个扫气口作为主扫气口,另一个扫气口作为辅扫气口,缸体缸壁外表面对应每个扫气口位置分别罩盖固定有侧盖,由侧盖和缸体对应位置缸壁围成扫气道。本发明气缸结构新颖,性能可靠,不仅达到减少尾气排放和满足排放法规的要求,而且降低了气缸的工作温度并提高了小型汽油机的功率。(The invention discloses a closed low-exhaust backflow scavenging passage cylinder for a small gasoline engine, which comprises a cylinder body, wherein the inner cavity of the cylinder body is arched upwards to form a combustion chamber; the lower part of one side cylinder wall of the cylinder body is provided with an air inlet, the other side cylinder wall of the cylinder body is provided with an air outlet, the cylinder walls at the two sides of the cylinder body between the air inlet and the air outlet are respectively provided with a scavenging port, one scavenging port is used as a main scavenging port, the other scavenging port is used as an auxiliary scavenging port, the position of the outer surface of the cylinder wall of the cylinder body corresponding to each scavenging port is respectively covered and fixed with a side cover, and a scavenging passage is enclosed by the side cover and the cylinder wall at the corresponding position of the cylinder body. The cylinder has novel structure and reliable performance, not only achieves the requirements of reducing exhaust emission and meeting emission regulations, but also reduces the working temperature of the cylinder and improves the power of the small gasoline engine.)

1. The utility model provides a small-size petrol is with closed low row of backward flow scavenging route cylinder, includes cylinder body (11), and open the crankcase that is used for connecting in cylinder body (11) bottom, and spark plug (10) to ignition in cylinder body (11) are installed to cylinder body (11) top, its characterized in that: the top of the inner cavity of the cylinder body (11) is arched upwards to form a combustion chamber (8), and the spark plug (10) ignites into the combustion chamber (8);

the lower part of the cylinder wall on one side of the cylinder body (11) is provided with an air inlet (2) used for being connected with a carburetor, the cylinder wall on the other side of the cylinder body (11) opposite to the air inlet (2) is provided with an exhaust port (5), the position of the exhaust port (5) is higher than that of the air inlet (2), the cylinder walls on the two sides of the cylinder body between the air inlet (2) and the exhaust port (5) are respectively provided with a scavenging port (6), the height of the upper edge of the scavenging port (6) is lower than that of the upper edge of the exhaust port (5), and the distance between the upper edge of the exhaust port (5) and the top of the cylinder body (11) is 13-14 times of the distance between the upper edge of the scavenging port (6) and the upper edge of the exhaust port (5);

one of the scavenging ports is used as a main scavenging port, the other scavenging port is used as an auxiliary scavenging port, the sectional area of the main scavenging port is larger than that of the auxiliary scavenging port, the central axes of the main scavenging port and the auxiliary scavenging port respectively form an included angle with the central axis of the cylinder body (11), the included angle between the central axis of the main scavenging port and the central axis of the cylinder body (11) is larger than that between the central axis of the auxiliary scavenging port and the central axis of the cylinder body (11), the outer surface of the cylinder wall of the cylinder body (11) corresponding to each scavenging port (6) is respectively covered and fixed with a side cover, the cylinder wall of the position corresponding to the side cover and the cylinder body (11) is encircled to form a scavenging passage, and the bottom of the scavenging passage is respectively communicated with the bottom of the inner cavity of the cylinder body (11).

2. The closed type low-exhaust scavenging passage cylinder for the small gasoline engine as set forth in claim 1, wherein: the combustion chamber (8) at the top of the inner cavity of the cylinder body (11) is an upwardly arched hemispherical chamber.

3. The closed type low-exhaust scavenging passage cylinder for the small gasoline engine according to claim 1 or 2, characterized in that: the ignition portion of the spark plug (10) is located at an intermediate position of the combustion chamber.

4. The closed type low-exhaust scavenging passage cylinder for the small gasoline engine as set forth in claim 1, wherein: the included angle between the central axis of the main scavenging port and the central axis of the cylinder body (11) is 130 degrees, and the included angle between the central axis of the auxiliary scavenging port and the central axis of the cylinder body (11) is 110 degrees.

5. The closed type low-exhaust scavenging passage cylinder for the small gasoline engine as set forth in claim 1, wherein: a plurality of horizontal radiating fins (7) are fixed on an upper portion of a cylinder wall of the cylinder body (11) in an annular sleeve mode, the top surface of the horizontal radiating fin on the uppermost layer is flush with the top surface of the cylinder body (11), a plurality of longitudinal radiating fins (9) are fixed on the top surface of the cylinder body (11), and two ends of each longitudinal radiating fin (9) extend to positions corresponding to the top surface of the horizontal radiating fin on the uppermost layer respectively and are in contact with the top surface of the horizontal radiating fin on the uppermost layer and are connected into a whole.

6. The closed type low-exhaust scavenging passage cylinder for the small gasoline engine as set forth in claim 5, wherein: the distance between the adjacent horizontal radiating fins (7) is equal to that between the adjacent longitudinal radiating fins (9).

7. The closed type low-exhaust scavenging passage cylinder for the small gasoline engine as set forth in claim 6, wherein: the distance between the adjacent horizontal radiating fins (7) and the distance between the adjacent longitudinal radiating fins (9) are both 4 mm.

8. The closed type low-exhaust scavenging passage cylinder for the small gasoline engine as set forth in claim 1, wherein: the distance between the upper edge of the exhaust port (5) and the top of the cylinder body (11) is 13.6 times of the distance between the upper edge of the scavenging port (6) and the upper edge of the exhaust port (5).

Technical Field

The invention relates to the field of gasoline engine cylinders, in particular to a closed low-exhaust backflow scavenging passage cylinder for a small gasoline engine.

Background

The small two-stroke gasoline engine has high power per liter, stable operation, reliable work, small volume and light weight, and is widely applied to the field of handheld garden tools such as brush cutters, chain saws, hair dryers and the like. The cylinder is an important part of the small gasoline engine, bears high mechanical load and thermal load, and has a complex geometric shape and uneven heating of each part.

The during operation of small-size gasoline engine, under the effect of the inside and outside difference in temperature of highest explosive pressure and cylinder wall, the cylinder receives considerable mechanical stress and thermal stress, owing to receive cylinder block structure and cooling air current around the influence that the cylinder flows, the cylinder block is last, well, lower part and temperature distribution all around are very inhomogeneous, and this makes the cylinder block warp great, if cylinder self lubrication condition is relatively poor, will aggravate the wearing and tearing of cylinder, increases the consumption of machine oil. In addition, the lateral pressure and sliding friction of the piston to the cylinder cause the cylinder to generate bending stress and abrasion. On the other hand, in order to meet the increasingly strict emission regulation requirements, the interior of the cylinder must be subjected to internal purification measures, and then the three-way catalyst is matched to be used as a catalyst medium for purifying tail gas, so that the requirements of environmental protection regulations can be met. The reaction of the catalyst and the exhaust gas is an exothermic reaction, which directly causes the temperature of the gasoline engine to be higher, resulting in the reliability reduction of the machine.

The conventional cylinder is formed by integral aluminum die-casting, the radiating fins are unreasonably arranged, the temperature difference of the periphery of the cylinder body is large, deformation and abrasion are easy to cause, the service life of a gasoline engine is shortened, and the safety risk of an operator is increased; on the other hand, the scavenging structure is usually a single scavenging structure, the scavenging port and the exhaust port are arranged oppositely, short-circuit scavenging is easily formed on the inner wall of the cylinder due to unstable scavenging airflow, waste gas is not easy to exhaust, and part of fresh combustible mixed gas directly escapes from the exhaust port, so that the exhaust condition is worsened and the power is reduced, and the requirements of regulations cannot be met.

Disclosure of Invention

The invention aims to provide a closed low-exhaust backflow scavenging passage cylinder for a small gasoline engine, which is used for solving the problems of unreasonable heat dissipation structure and unstable scavenging caused by a single scavenging structure of the cylinder for the gasoline engine in the prior art.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a closed low-exhaust backflow scavenging passage cylinder for a small gasoline engine comprises a cylinder body (11), wherein the bottom of the cylinder body (11) is open and is connected with a crankcase, a spark plug (10) for igniting the inside of the cylinder body (11) is installed at the top of the cylinder body (11), the top of the inner cavity of the cylinder body (11) is arched upwards to form a combustion chamber (8), and the spark plug (10) ignites the inside of the combustion chamber (8);

the lower part of the cylinder wall on one side of the cylinder body (11) is provided with an air inlet (2) used for being connected with a carburetor, the cylinder wall on the other side of the cylinder body (11) opposite to the air inlet (2) is provided with an exhaust port (5), the position of the exhaust port (5) is higher than that of the air inlet (2), the cylinder walls on the two sides of the cylinder body between the air inlet (2) and the exhaust port (5) are respectively provided with a scavenging port (6), the height of the upper edge of the scavenging port (6) is lower than that of the upper edge of the exhaust port (5), and the distance between the upper edge of the exhaust port (5) and the top of the cylinder body (11) is 13-14 times of the distance between the upper edge of the scavenging port (6) and the upper edge of the exhaust port (5);

one of the scavenging ports is used as a main scavenging port, the other scavenging port is used as an auxiliary scavenging port, the sectional area of the main scavenging port is larger than that of the auxiliary scavenging port, the central axes of the main scavenging port and the auxiliary scavenging port respectively form an included angle with the central axis of the cylinder body (11), the included angle between the central axis of the main scavenging port and the central axis of the cylinder body (11) is larger than that between the central axis of the auxiliary scavenging port and the central axis of the cylinder body (11), the outer surface of the cylinder wall of the cylinder body (11) corresponding to each scavenging port (6) is respectively covered and fixed with a side cover, the cylinder wall of the position corresponding to the side cover and the cylinder body (11) is encircled to form a scavenging passage, and the bottom of the scavenging passage is respectively communicated with the bottom of the inner cavity of the cylinder body (11).

Furthermore, a combustion chamber (8) at the top of the inner cavity of the cylinder body (11) is an upwardly arched hemispherical chamber.

Further, an ignition portion of the ignition plug (10) is located at an intermediate position of the combustion chamber.

Furthermore, the included angle between the central axis of the main scavenging port and the central axis of the cylinder body (11) is 130 degrees, and the included angle between the central axis of the auxiliary scavenging port and the central axis of the cylinder body (11) is 110 degrees.

Furthermore, a plurality of horizontal radiating fins (7) are fixed on an upper ring sleeve of the cylinder wall of the cylinder body (11), the top surface of the horizontal radiating fin on the uppermost layer is flush with the top surface of the cylinder body (11), a plurality of longitudinal radiating fins (9) are fixed on the top surface of the cylinder body (11), and two ends of each longitudinal radiating fin (9) respectively extend to positions corresponding to the top surface of the horizontal radiating fin on the uppermost layer to be contacted and connected into a whole.

Further, the distance between the adjacent horizontal radiating fins (7) is equal to the distance between the adjacent longitudinal radiating fins (9).

Furthermore, the distance between the adjacent horizontal radiating fins (7) and the distance between the adjacent longitudinal radiating fins (9) are both 4 mm.

Furthermore, the distance between the upper edge of the exhaust port (5) and the top of the cylinder body (11) is 13.6 times of the distance between the upper edge of the scavenging port (6) and the upper edge of the exhaust port (5).

The invention can fully mix air and fuel, improve scavenging efficiency, stabilize scavenging direction, reduce working temperature of the cylinder, and effectively improve power of the engine and reduce exhaust emission value.

According to the invention, firstly, a reasonable hemispherical combustion chamber and an air passage with good performance are arranged according to the combustible mixed gas forming and combustion mode, the ignition position of the spark plug is arranged in the middle of the combustion chamber to ensure that the combustible mixed gas is fully combusted, and the minimum flame propagation distance and higher turbulence intensity can be ensured; meanwhile, the surface-to-volume ratio of the combustion chamber is reduced, the phenomena of deflagration and pre-ignition are avoided, a reasonable compression ratio is kept, and a small air squeezing gap is reserved to ensure that the gasoline engine has good performance.

The invention further reasonably arranges the shape and the structure of the radiating fins, adopts a horizontal and longitudinal mixed radiating fin, the horizontal radiating fin is arranged at the position of the cylinder body, and the longitudinal radiating fin is arranged at the top of the combustion chamber and is horizontally and longitudinally connected, so that not only can the heat be reasonably distributed on the radiating fins, but also the heat can be guided to cool air, and the resistance of an air passage is reduced; the surface area of the heat radiating fins is kept to be suitable for the heat quantity radiated, so that the temperature of the whole cylinder is evenly distributed and the temperature is lowest.

In addition, the invention optimizes the structural form of the scavenging passage, adopts a double-channel scavenging passage structure, and is respectively a main scavenging port and an auxiliary scavenging port with different sectional areas and angles; the independent left and right side covers are added, and the bent channel is kept to guide the scavenging air flow to firstly impact the cylinder wall opposite to the exhaust port, and the scavenging air flow is bent upwards under the guidance of the cylinder wall and then is bent downwards along the top of the combustion chamber to flow to the exhaust port. The scavenging section is enlarged, the scavenging airflow is organized better, and the short-circuit scavenging loss is avoided.

Finally, the invention optimally designs the height of the exhaust port, on one hand, the height ensures that the pressure of the cylinder is reduced to be close to the pressure of the crankcase when the scavenging port is opened so as to avoid the waste gas from being greatly guided into the crankcase from the scavenging port, and on the other hand, the effective stroke loss caused by the height of the exhaust window and the deterioration of economic and emission indexes in the later exhaust time process are avoided.

The cylinder has novel structure and reliable performance, not only achieves the requirements of reducing exhaust emission and meeting emission regulations, but also reduces the working temperature of the cylinder and improves the power of the small gasoline engine.

Drawings

FIG. 1 is a side cross-sectional view of the assembled crankcase and crankcase structure of the present invention.

Fig. 2 is a side view of the outer structure of the present invention.

Fig. 3 is a side sectional view of the internal structure of the present invention.

Fig. 4 is a rear view of the outer structure of the present invention.

Fig. 5 is an exploded view of the assembly of the present invention with the scavenging side cover.

Fig. 6 is a front sectional view of the internally assembled piston of the present invention at top dead center.

FIG. 7 is a front sectional view of the internally assembled piston of the present invention at the bottom dead center.

FIG. 8 is a schematic view of the height difference between the scavenging port and the exhaust port of the present invention.

The notation in the figure is: 1, a carburetor; 2, an air inlet; 3 a crankcase; 4, deep groove ball bearings; 5 an exhaust port; 6, a scavenging port; 7 horizontal radiating fins; 8, a combustion chamber; 9 longitudinal radiating fins; 10 a spark plug; 11 air cylinders; 12 a kill-switch; 13 left scavenging side cover; 14 right scavenging side cover; 15 piston.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

As shown in figures 1-7, the invention relates to a closed low-exhaust backflow scavenging passage cylinder for a small gasoline engine, which comprises a cylinder body 11, wherein the bottom of the cylinder body 11 is open, the top of the cylinder body 11 is closed, the bottom of the cylinder body 11 is open and fixedly connected to a crankcase 3, a crankshaft is rotatably arranged in the crankcase 3 through a deep groove ball bearing, a piston 15 is slidably arranged in an inner cavity of the cylinder body 11, and the crankshaft in the crankcase 3 is connected with the piston 15 in the cylinder body 11 through a connecting rod.

A plurality of layers of horizontal radiating fins 7 are fixed on the outer side surface of the upper cylinder wall of the cylinder body 11 in an annular sleeve mode, the top surface of the horizontal radiating fin on the uppermost layer is flush with the top surface of the cylinder body 11, a plurality of longitudinal radiating fins 9 are fixed on the top surface of the cylinder body 11, each longitudinal radiating fin 9 is perpendicular to the horizontal radiating fin 7 respectively, and two ends of each longitudinal radiating fin 9 in the extending direction extend to be in contact with the horizontal radiating fin on the uppermost layer and are fixedly connected into a whole.

The top of the inner cavity of the cylinder 11 is shaped like a hemisphere to arch upwards so as to form a combustion chamber 8, the top of the cylinder 11 is provided with a spark plug 10, the ignition part of the spark plug 10 is positioned in the middle position in the combustion chamber 8, and the spark plug 10 ignites into the combustion chamber 8.

An air inlet 2 is arranged at the lower part of the cylinder wall at the rear side of the cylinder body 11, an air outlet 5 is arranged at the cylinder wall at the front side of the cylinder body 11, and the position of the air outlet 5 is higher than that of the air inlet 2. The left and right cylinder walls of the cylinder body 11 are respectively provided with a scavenging port 6. A carburetor 1 of a gasoline engine is mounted on a rear side cylinder wall of a cylinder block 11 and communicates with an intake port 2.

Scavenging side covers are respectively fixed on the outer surfaces of the left and right side cylinder walls of the cylinder body 11 at positions corresponding to the scavenging ports 6, a scavenging passage is respectively defined by the left scavenging side cover 13 and the right scavenging side cover 14 and the cylinder wall at the position corresponding to the cylinder body 11, and the bottom of the scavenging passage is respectively communicated with the bottom of the inner cavity of the cylinder body 11. The left scavenging side cover 13 and the right scavenging side cover 14 are respectively matched with the scavenging port 6 at the corresponding position to form a left combustible gas mixture flow passage and a right combustible gas mixture flow passage.

First, when the piston 15 moves upward and reaches a certain position, the skirt portion thereof opens the intake port 2, and the combustible mixture is introduced from the carburetor 1 through the intake port 2 into the lower portion of the cylinder block 11 where it joins the crankcase 3. The piston 15 continues to move upwards to reach the position near the top dead center, the spark plug 10 starts to ignite at the moment, and the combustible mixed gas ignites and burns in the hemispherical combustion chamber 8; the combustion chamber 8 has compact structure and small surface volume, and forms a small air extrusion gap with the piston 15. While the spark plug 10 is arranged in the middle of the combustion chamber, the propagation distance of the flame center to the peripheral edge is the shortest. At the moment, the pressurized fresh combustible mixture is violently combusted in a short time to release heat, high-temperature and high-pressure gas is generated to expand and do work, the piston 15 is pushed to move downwards, the combustible mixture sucked before pressurization is carried out by means of the pressure difference generated in the crankcase 3 by the downward movement of the piston 15, and the combustible mixture is pushed to enter a scavenging passage on the side face of the cylinder body 11.

When the piston 15 continues to move downwards to a certain position, the top of the piston starts to open the exhaust port 5, high-temperature waste gas in the combustion chamber 8 rushes to the exhaust port 5 at the speed of sound and starts to exhaust, and the height of the exhaust port 5 ensures that the pressure of the cylinder is reduced to be close to the pressure of the crankcase 3 when the scavenging port is opened, so that the waste gas is prevented from being guided into the crankcase from the scavenging port in a large amount, and the economic loss of effective stroke and the deterioration of emission indexes caused by the height of an exhaust window are avoided.

When the piston 15 moves upwards, the distance from the scavenging port 5 to the exhaust port 6 is the section of the inner wall of the cylinder 11, the charge is forcibly discharged by the upward movement of the piston 15, and if the height of the exhaust port 5 is far higher than that of the scavenging port 6, a large amount of fresh mixed gas in the cylinder is discharged along with the exhaust gas due to the fact that the air intake is finished, so that the oil consumption is increased, meanwhile, the HC emission is increased, and therefore the distance from the scavenging port 6 to the exhaust port 5 is the smaller and the better. The top face of the piston 15 is used to open and close the exhaust port 5 and the scavenging port 6, so that the opening and closing times of the two types of ports are only related to the positions of the upper edges of the ports. The distance between the exhaust port 5 and the scavenging port 6 and the top surface of the cylinder 11 is important, and the shorter the distance is, the higher the rotating speed of the engine is, under the condition of ensuring the effective compression ratio, because the time for scavenging exhaust gas is shortened and the exhaust gas is opened in advance at high speed, the exhaust and scavenging time is prolonged. As shown in FIG. 8, in the present invention, the distance between the upper edge of the exhaust port 5 and the top of the cylinder 11 is 13-14 times, preferably 13.6 times, the distance between the upper edge of the scavenging port 6 and the upper edge of the exhaust port 5, for example, the distance between the upper edge of the exhaust port 5 and the top of the cylinder 11 is 25.8mm, and the distance between the upper edge of the scavenging port 6 and the upper edge of the exhaust port 5 is 1.9 mm.

When the piston 15 continues to move downwards, the scavenging ports 6 on the left side and the right side of the cylinder body 11 are opened at the moment, the cylinder body 11 is of a double-channel structure on the left side and the right side, the scavenging port on the left side in the scavenging ports is a main scavenging port, the scavenging port on the right side is an auxiliary scavenging port, the corresponding left scavenging passage is a main scavenging passage, and the right scavenging passage is an auxiliary scavenging passage. The sectional area of the main scavenging port is larger than that of the auxiliary scavenging port, an included angle of 130 degrees is formed between the central axis of the left scavenging port and the central axis of the cylinder body 11, and an included angle of 110 degrees is formed between the central axis of the auxiliary scavenging port and the central axis of the cylinder body 11. The air outlet of the main scavenging port cleans the waste gas at the bottom, and the air outlet of the auxiliary scavenging port cleans the waste gas at the top. The pre-compressed fresh combustible mixed gas starts to enter the scavenging passage and rushes to the cylinder wall opposite to the exhaust port 5 through the corresponding scavenging port 6, and is bent upwards under the guidance of the cylinder wall to push the high-temperature waste gas discharged after the combustible mixed gas in the combustion chamber 8 is combusted to flow downwards to the exhaust port 5 along the top turning, namely the pressurized fresh mixed gas subjected to the scavenging port rectification treatment is utilized to drive the high-temperature waste gas after the combustion.

The piston moves upwards after reaching the bottom dead center, the scavenging port 6 and the exhaust port 5 are closed in sequence, the skirt part of the piston opens the air inlet 2 at a certain moment, combustible mixed gas starts to enter air and is compressed, and therefore a cycle is completed, and the cycle is repeated.

The invention can meet the strict rule and effectively improve the service performance of the engine. Aiming at the large amount of heat transferred to the cylinder when the small gasoline engine works, particularly the temperature around a combustion chamber is highest; horizontal fins 7 are arranged at intervals of 4 mm on the circumference of the cylinder 11, and longitudinal fins 9 are arranged at intervals of 4 mm on the top of the cylinder 11. The horizontal fins 7 are arranged concentratedly around the combustion chamber 8, both sides of the ignition plug 10, and the intake and exhaust ports, while the longitudinal fins 9 are arranged in the upper region of the intake and exhaust ports. The direction of heat flow formed by the heat generated by the combustion of the combustible mixture in the combustion chamber 8 is consistent with the direction of the horizontal radiating fins 7 and the longitudinal radiating fins 9, so that the heat in the area can be directly transmitted to the radiating fins, and the effect is better. Meanwhile, the cooling air is guided, when the distance between the cooling fins is 4 mm, laminar layers between the cooling air are far away, and turbulent layers are strengthened, so that turbulent motion is formed between every two adjacent cooling fins, the air resistance is reduced, and the heat dissipation effect is strengthened; the surface area of the radiating fins is kept to be adaptive to the heat dissipated, so that the temperature of the whole cylinder body 11 is evenly distributed and is the lowest, the heat load of an engine is effectively reduced, and the durable service life of the whole engine is prolonged.

The embodiments of the present invention are described only for the preferred embodiments of the present invention, and not for the limitation of the concept and scope of the present invention, and various modifications and improvements made to the technical solution of the present invention by those skilled in the art without departing from the design concept of the present invention shall fall into the protection scope of the present invention, and the technical content of the present invention which is claimed is fully set forth in the claims.