CN211038828U

CN211038828U - Two-stroke piston engine for aviation

Info

Publication number: CN211038828U
Application number: CN201921334745.6U
Authority: CN
Inventors: 陈军磊
Original assignee: Quadrant Space Tianjin Technology Co Ltd
Current assignee: Quadrant Space Tianjin Technology Co Ltd
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2020-07-17
Anticipated expiration: 2029-08-16

Abstract

The application provides a two-stroke piston engine for aviation; the combustion chamber of the engine comprises a piston top spherical surface arranged at the top of the piston, a first wedge-shaped surface and a second wedge-shaped surface which are sequentially arranged on the side wall of the combustion chamber from bottom to top, and a hemispherical surface which is positioned at the top and is connected with the second wedge-shaped surface; a first included angle is formed between the first wedge-shaped surface and the side wall of the piston, and a second included angle is formed between the second wedge-shaped surface and the horizontal direction; the first included angle is smaller than the second included angle. This application makes the piston form crowded air current from up moving down, and the gas in two half wedge regions is extruded by the piston when the piston reaches top dead center, collides each other in the hemisphere region, and after the collision, the gas velocity of flow is fast, and flame propagation speed accelerates to form the motion that promotes the burning, thereby make the burning rapider, fully improve fuel utilization ratio, promote engine power.

Description

Two-stroke piston engine for aviation

Technical Field

The application relates to the technical field of engines, in particular to an aviation two-stroke piston engine.

Background

The two-stroke engine includes casing, cylinder, piston, air inlet, air outlet, fuel oil, etc. The cylinder and the piston are core components of the two-stroke engine, combustion occurs in a combustion chamber of the cylinder, and explosion pressure generated by the combustion pushes the piston to do reciprocating linear motion in the cylinder. When the piston is positioned at the top dead center, the space formed by the top of the piston and the cylinder is called a combustion chamber. The shape of the combustion chamber has become an important factor affecting the performance of two-stroke engines. As is well known, the two-stroke engine crankshaft rotates once to do work, and the two-stroke engine crankshaft rotates once to do work twice, compared with the four-stroke engine crankshaft, the air intake and exhaust time is shortened by half, and excellent air intake and exhaust airflow organization and sufficient fuel combustion are key technologies for improving the effective output power of the two-stroke engine.

The existing high-power two-stroke piston engine combustion chamber mostly adopts a wedge-shaped combustion chamber or a spherical combustion chamber, the piston is mostly flat-topped or wedge-shaped, and scavenging is in a form of direct-flow scavenging or backflow scavenging. The two-stroke engine generally pre-compresses combustible mixed gas in a casing, and opens an air inlet and an air outlet through the movement of a piston, thereby controlling the entry of fresh mixed gas and the discharge of waste gas after combustion; fresh gas flows in the air inlet channel, enters the cylinder and extrudes waste gas combusted in the cylinder, so that air inlet and air exhaust are completed; in the prior art, scavenging is insufficient, combustible mixed gas is easy to cause short circuit, and the mixed gas is directly discharged from an exhaust port without combustion, so that the problems of poor economic performance, difficult starting and the like of an engine are caused. In addition, in the prior art, the flowability of the gas at the edge of the combustion chamber is poor, so that the time for the combustible mixed gas at the edge to participate in combustion is late, and the combustion is insufficient, thereby influencing the effective power output of the engine and the HC (hydrocarbon) emission of the engine.

Disclosure of Invention

The technical problem that this application will be solved provides an aviation two-stroke piston engine.

The technical problem that this application further solved provides an aviation is with two-stroke piston engine, the combustion chamber of engine includes the piston table surface who sets up at the piston top, from supreme first wedge face and the second wedge face of setting gradually at the combustion chamber lateral wall down, be located the top and with the hemisphere face that the second wedge face links up; a first included angle is formed between the first wedge-shaped surface and the side wall of the piston, and a second included angle is formed between the second wedge-shaped surface and the horizontal direction; the first included angle is smaller than the second included angle.

According to the technical scheme provided by the embodiment of the application, the range of the first included angle is 5 degrees to 10 degrees, and the range of the second included angle is 5 degrees to 15 degrees.

According to the technical scheme provided by the embodiment of the application, a first fillet is arranged between the first wedge-shaped surface and the second wedge-shaped surface; and a second fillet guide is arranged between the second wedge-shaped surface and the hemispherical surface, and the second fillet guide is 3-10 times, preferably 3-5 times of the first fillet guide.

According to the technical scheme provided by the embodiment of the application, the projected area of the annular region formed between the bottom end loop line and the top end loop line of the second wedge-shaped surface accounts for 20-50% of the maximum cross-sectional area of the combustion chamber.

According to the technical scheme provided by the embodiment of the application, the radius of the top spherical surface of the piston is 10-15 times of that of the semi-spherical surface.

According to the technical scheme provided by the embodiment of the application, the vertical distance between the center point of the piston top spherical surface and the edge of the firepower bank is 1-3 mm.

According to the technical scheme provided by the embodiment of the application, a cylinder of the engine is fixed on a casing, and a piston assembly is arranged in the cylinder; the combustion chamber is positioned at the top of the piston in the cylinder; an exhaust port is arranged on the side wall of the cylinder, and the outlet direction of the exhaust port is arranged in an inclined downward manner; the caliber of the exhaust port gradually widens from inside to outside.

According to the technical scheme that this application embodiment provided, the cylinder inner face is equipped with the cladding material.

According to the technical scheme provided by the embodiment of the application, the side wall of the cylinder is provided with a main scavenging passage and at least one auxiliary scavenging passage.

The application has the advantages and positive effects that: according to the technical scheme, the first wedge-shaped surface and the second wedge-shaped surface are arranged on the side wall of the combustion chamber of the piston engine, a first included angle is formed between the first wedge-shaped surface and the side wall of the piston, and a second included angle is formed between the second wedge-shaped surface and the horizontal direction; the first included angle is smaller than the second included angle. The wedge-shaped area formed between the first wedge-shaped surface and the second wedge-shaped surface enables the piston to form an air squeezing flow when moving from bottom to top, the air squeezing flow increases the flow speed, and the air at the edge of the combustion chamber rapidly participates in the air flow, so that the propagation speed of flame is increased, the overall combustion time is shortened, and the combustion is accelerated; when the piston reaches the top dead center, the gas in the double-half wedge-shaped area is extruded by the piston and collides with each other in the hemispherical area, and after the collision, the gas flow rate is accelerated, the flame propagation speed is accelerated, so that the movement for promoting combustion is formed, the combustion is quicker and more sufficient, the fuel utilization rate is improved, and the engine power is improved.

The extruded airflow can also promote scavenging, and air inlet and exhaust can be better completed; the squish flow increases the flow rate by wedge-type squish, which creates a jet of gas, thereby increasing the flow rate.

The design of the wedge-shaped area overturns the design of straight interface propagation of flame propagation direction in the traditional combustion chamber, and the side wall of the bent combustion chamber formed by the first wedge-shaped surface and the second wedge-shaped surface enables the flame to form zigzag propagation in the flame propagation, so that the flame propagation area and speed are further increased.

According to the technical scheme that this application embodiment provided, through design slope decurrent gas vent and supplementary scavenging route, the gas vent sets up certain inclination, and expands gradually, reduces carminative velocity of flow, makes the exhaust have a suitable backpressure, avoids directly discharging the engine at fresh oil-gas mixture when the piston does not close the gas vent, can avoid advancing, the exhaust short circuit, increases marginal combustible mixture flow velocity, promotes the burning relative velocity, promotes the mechanical efficiency and the fuel utilization ratio of engine.

In addition to the technical problems addressed by the present application, the technical features constituting the technical solutions, and the advantages brought by the technical features of the technical solutions described above, other technical problems solved by the present application, other technical features included in the technical solutions, and advantages brought by the technical features will be further described in detail with reference to the accompanying drawings.

Drawings

FIG. 1 is a schematic view of a combustion chamber according to a first embodiment of the present application;

FIG. 2 is a schematic view of the gas flow within the combustion chamber of the first embodiment of the present application;

FIG. 3 is a perspective cross-sectional structural view of an engine assembly according to a second embodiment of the present application;

FIG. 4 is an enlarged schematic view of portion A of FIG. 3;

FIG. 5 is a cross-sectional view of an engine according to a second embodiment of the present application.

FIG. 6 is a schematic view of a cylinder according to a second embodiment of the present application;

FIG. 7 is a schematic view of a cylinder structure perpendicular to the cross-section of FIG. 5 of a cylinder according to a second embodiment of the present invention;

FIG. 8 is a schematic view of a piston according to a second embodiment of the present application;

in the figure: 1. a piston; 2. a piston top spherical surface; 3. a first wedge-shaped face; 4. a second wedge-shaped face; 5. a hemispherical surface; 6. a spark plug; 7. a cylinder; 8. an auxiliary scavenging path; 9. a connecting rod; 10. a case;

11. an exhaust port; 12. a main scavenging path; 13. piston thrust surface, 14, hollowed out surface.

Detailed Description

The following further describes embodiments of the present application with reference to the drawings. It should be noted that the description of the embodiments is provided to help understanding of the present application, but the present application is not limited thereto. In addition, the technical features mentioned in the embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.

Example one

The piston engine combustion chamber structure is shown in fig. 1, and comprises a piston top spherical surface 2 arranged at the top of a piston, a first wedge-shaped surface 3 and a second wedge-shaped surface 4 which are sequentially arranged on the side wall of the combustion chamber from bottom to top, and a hemisphere surface 5 which is positioned at the top and is connected with the second wedge-shaped surface 4, wherein a first included angle α is formed between the first wedge-shaped surface 3 and the side wall of the piston, a second included angle β is formed between the second wedge-shaped surface and the horizontal direction, the first included angle α is smaller than the second included angle β, in the embodiment, the first included angle α is 6 degrees, the second included angle β is 10 degrees, the first included angle is smaller than the second included angle, so that the side wall of the combustion chamber forms a bent section of side wall from the top dead center, the side wall gradually widens and then gradually narrows, so that an extruded gas flow is formed in the combustion chamber, as shown in fig. 1, a spark plug 6 is arranged at the top of the hemisphere surface 5, as shown in fig. 2 and fig. 3, when the piston moves to the top dead center, the gas flow of the side wall of the combustion chamber moves, the first wedge-shaped gas flow is gradually widened, the first wedge-shaped wedge-.

According to requirements, the area ratio of the flow squeezing area can be designed by designing the length of the first wedge-shaped face 3 and the length of the second wedge-shaped face 4, so that the area of the flow squeezing area accounts for 20% -50% of the maximum cross-sectional area of the combustion chamber, fuel can be effectively squeezed, mixed and combusted, and the combustion efficiency is improved. The area of the squish flow area refers to the annular projected area formed between the bottom end and the top end of the second wedge-shaped surface 4, and the maximum cross section of the combustion chamber is the cross section of the circular line at the bottom end of the second wedge-shaped surface 4.

In other embodiments, the first included angle may have other values ranging from 5 ° to 10 °, and the second included angle may have other values ranging from 5 ° to 15 °. The second included angle is greater than the first included angle for the second wedge face is followed up and is dwindled gradually, can improve air velocity on the one hand, can control flow direction in addition, promotes the burning.

In this embodiment, a first fillet R1 is disposed between the first wedge-shaped surface and the second wedge-shaped surface; a second fillet R2 is disposed between the second wedge-shaped surface and the hemispherical surface, and the second fillet R2 is 3-10 times, preferably 3-5 times, of the first fillet R1. The design of fillet can make the air current more smooth and easy, and the second fillet is big than first fillet in order to comply with the inclination difference of second wedge-shaped face and second wedge-shaped face, and the change of complying with the air current better improves the gas flow rate.

In the embodiment, the radius SR1 of the piston spherical crown surface is 10-15 times of the radius SR2 of the hemispherical surface.

In the embodiment, the vertical distance between the central point of the piston top spherical surface and the edge of the fire bank is 1-3 mm; the heat transfer efficiency is determined by unification of heat conduction, engine heat dissipation, metal deformation and the like, the heat transfer is contact heat transfer, the contact depends on a piston ring, the deformation is different due to the difference of distances, and therefore the heat transfer is different, and the friction loss is different; and the distance of 1-3mm is designed to ensure that the heat transfer efficiency from the piston to the cylinder is high, so that the friction loss is small.

Example two

Fig. 5 to 7 are schematic structural diagrams of a two-stroke piston engine for aviation according to the embodiment, including a casing 10, a cylinder 7 fixed on the casing 10, and a piston assembly located in the cylinder 7, where the piston assembly includes a piston 1 and a connecting rod 9, and one end of the piston 1 away from a combustion chamber is rotatably connected with the connecting rod 9; the piston 1 is arranged in a cylinder 7 in a sliding manner, an exhaust port 11 is arranged on the side wall of the cylinder 7, and the outlet direction of the exhaust port 11 is arranged obliquely downwards; the caliber of the exhaust port 11 gradually becomes wider from inside to outside; the structure of the combustion chamber of the engine in the embodiment is the same as that of the combustion chamber in the first embodiment; in this embodiment, the side wall of the cylinder is provided with a plated surface.

As shown in fig. 8, in the present embodiment, the piston 1 is provided with pin holes which intersect perpendicularly with respect to the piston center axis; the side surface of the piston 1 is a piston thrust surface 13, and the middle part of the piston is provided with a hollow surface 14.

The cylinder 7 comprises a scavenging passage, and the scavenging passage and the exhaust port are communicated to the combustion chamber; fresh air and fuel oil are mixed in the scavenging passage, enter the casing 10 through a reed valve, are pre-compressed in the casing, control the opening of the scavenging passage through the motion of a piston, and the mixed fuel enters a combustion chamber through the scavenging passage; in the present embodiment, the scavenging path includes a main scavenging path 12 and an auxiliary scavenging path 8; in the present embodiment, the number of the auxiliary scavenging ducts 8 is 2, and in other embodiments, the number of the auxiliary scavenging ducts may also be multiple; those skilled in the art can understand that the auxiliary scavenging passage and the main scavenging passage are both air intake passages, and the difference between the auxiliary scavenging passage and the main scavenging passage is that the paths are different, and chambers communicated with both ends of the auxiliary scavenging passage are the same, which is not described herein; the design purpose of the auxiliary scavenging passage is to increase the air inlet sectional area, so that air can be more fully introduced in the same time, and the direction of air flow can be effectively changed by adopting the main and auxiliary air inlet passages, and the combusted waste gas can be more effectively and fully extruded.

The mixed fuel is pre-compressed in the casing 10 and moves linearly back and forth in the cylinder 7 along with the piston 1 under the action of the connecting rod 9. With the movement of the piston 1, the auxiliary scavenging passage 8 and the main scavenging passage 12 are opened to start air intake; when the exhaust port 11 is opened, the inclination angle of the exhaust port 11 limits the flowing direction of gas to form backflow scavenging, exhaust gas in the cylinder is discharged, the exhaust gas is discharged from the exhaust port 11, the exhaust port 11 is provided with a certain inclination angle and gradually expands to reduce the flow speed of the exhaust gas, so that the exhaust gas has proper back pressure, and the fresh oil-gas mixture is prevented from being directly discharged out of the engine when the exhaust port 11 is not closed by the piston 1, thereby improving the efficiency of the engine and reducing the oil consumption of the engine.

In the embodiment, the distance between the top dead center of the piston 1 and the cylinder head mounting surface of the cylinder 7 is H1, the distance between the bottom end of the first wedge-shaped surface 3 and the cylinder head mounting surface is H2, the distance between the top end of the first wedge-shaped surface 4 and the cylinder head mounting surface is H3, and the size design of H1, H2 and H3 is set by a user according to parameters such as the compression ratio and the stroke of the engine.

The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions and alterations can be made herein without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims.

Claims

1. The two-stroke piston engine for aviation is characterized in that a combustion chamber of the engine comprises a piston top spherical surface arranged at the top of a piston, a first wedge-shaped surface and a second wedge-shaped surface which are sequentially arranged on the side wall of the combustion chamber from bottom to top, and a hemispherical surface which is positioned at the top and is connected with the second wedge-shaped surface; a first included angle is formed between the first wedge-shaped surface and the side wall of the piston, and a second included angle is formed between the second wedge-shaped surface and the horizontal direction; the first included angle is smaller than the second included angle.

2. An aeronautical two-stroke piston engine according to claim 1, wherein the first included angle ranges from 5 ° to 10 ° and the second included angle ranges from 5 ° to 15 °.

3. An aeronautical two-stroke piston engine according to claim 1, wherein a first fillet is provided between the first wedge face and the second wedge face; and a second fillet guide is arranged between the second wedge-shaped surface and the hemispherical surface and is 3-10 times of the first fillet guide.

4. An aeronautical two-stroke piston engine according to claim 1, wherein a first fillet is provided between the first wedge face and the second wedge face; and a second fillet guide is arranged between the second wedge-shaped surface and the hemispherical surface and is 3-5 times of the first fillet guide.

5. An aeronautical two-stroke piston engine according to claim 1, wherein the radius of the piston dome surface is 10-15 times the radius of the hemisphere.

6. An aeronautical two-stroke piston engine according to claim 1, wherein the vertical distance between the centre point of the piston crown surface and the fire land edge is 1-3 mm.

7. An aviation two-stroke piston engine according to claim 1, wherein the projected area of the annular region formed between the bottom and top end contours of the second wedge surface is 20% to 50% of the maximum cross-sectional area of the combustion chamber.

8. An aviation two-stroke piston engine according to any one of claims 1 to 6, characterised in that a cylinder of the engine is secured to a casing, a piston assembly being provided in the cylinder; the combustion chamber is positioned at the top of the piston in the cylinder; an exhaust port is arranged on the side wall of the cylinder, and the outlet direction of the exhaust port is arranged in an inclined downward manner; the caliber of the exhaust port gradually widens from inside to outside.

9. A two-stroke piston engine according to claim 8, characterised in that the side wall of the cylinder is provided with a main scavenging duct and at least one auxiliary scavenging duct.

10. A two-stroke piston engine according to claim 8, characterised in that the inner face of the cylinder is provided with a coating.