CN219974609U - Engine exhaust structure and two-cycle engine - Google Patents

Abstract

The utility model discloses an engine exhaust structure and a two-stroke engine, which comprise an exhaust pipe body arranged at an exhaust port of the engine, wherein the end part of the exhaust pipe body is closed, and an exhaust hole for exhausting exhaust gas in the engine is formed in the exhaust pipe body; according to the engine exhaust structure and the two-stroke engine, through the arrangement of the exhaust pipe body and the exhaust guide pipe, the power of the engine at a specific rotating speed is improved, fuel oil can be fully combusted, and the oil consumption is reduced; the structure is simple, and the weight of the exhaust pipe is reduced to the maximum extent; the direct discharge amount of unburned fuel is reduced.

Description

Engine exhaust structure and two-cycle engine

Technical Field

The utility model relates to the field of designing two-stroke engines, in particular to an engine exhaust structure and a two-stroke engine.

Background

The two-stroke engine is widely applied to aircrafts due to high power and large torque, and a beam back pressure resonant cavity is usually adopted by the two-stroke engine to increase the engine power in the conventional use process so as to increase the exhaust back pressure and reduce the noise, but the device has a complex structure and large weight. For this reason, in aviation two-stroke engines, an in-line method is often used to reduce the exhaust weight, but the in-line method has problems of high oil consumption, high noise, serious power loss and the like.

The two-stroke engine operating cycle is completed by scavenging-compression-combustion-exhaust gas in two immediately following steps, the negative pressure created by the exhaust gas causing part of the inhaled fresh mixture to be expelled from the combustion chamber with the exhaust gas, thereby losing part of the energy and polluting the environment.

Therefore, a back pressure device with a specific rotating speed needs to be designed, so that back pressure waves generated by exhaust gas are coupled with the specific rotating speed of the engine, and fresh mixed gas sucked into the exhaust gas is back pressure into the combustion chamber, so that fuel oil is fully combusted, the power of the engine is improved, and the use oil consumption is reduced.

Disclosure of Invention

In view of this, the exhaust structure of the engine of the utility model, through setting up body of the exhaust pipe and exhaust conduit, has promoted the power under the specific rotational speed of the engine, let the fuel burn fully, have reduced the oil consumption; the structure is simple, and the weight of the exhaust pipe is reduced to the maximum extent; the direct discharge amount of unburned fuel is reduced.

An engine exhaust structure comprises an exhaust pipe body arranged at an exhaust port of an engine, wherein the end part of the exhaust pipe body is closed, and an exhaust hole for exhausting exhaust gas in the engine is formed in the exhaust pipe body.

Further, the exhaust hole is connected with an exhaust duct.

Further, an included angle alpha is formed between the exhaust duct and the exhaust pipe body, and the included angle alpha is 85-90 degrees.

Further, the distance between the exhaust duct and the exhaust port of the engine is 1/4-1/3 of the length of the exhaust pipe body.

Further, the exhaust pipe body and the exhaust duct form a T-shaped structure.

A two-stroke engine having the above engine exhaust structure mounted thereon.

The beneficial effects of the utility model are as follows:

according to the engine exhaust structure, through the arrangement of the exhaust pipe body and the exhaust guide pipe, the power of the engine at a specific rotating speed is improved, fuel oil can be fully combusted, and the oil consumption is reduced; the structure is simple, and the weight of the exhaust pipe is reduced to the maximum extent; the direct discharge amount of unburned fuel is reduced.

Drawings

The utility model is further described below with reference to the accompanying drawings and examples:

FIG. 1 is a cross-sectional view A-A of FIG. 2;

FIG. 2 is a schematic view of an exhaust pipe installation of the present utility model;

fig. 3 is a chart of airway timing phase of the present utility model.

Detailed Description

FIG. 1 is a cross-sectional view A-A of FIG. 2; FIG. 2 is a schematic view of an exhaust pipe installation of the present utility model; FIG. 3 is a chart of airway timing phase of the present utility model; as shown in the figure, the exhaust structure of the engine comprises an exhaust pipe body 4 arranged at an exhaust port 3 of the engine, wherein the end part of the exhaust pipe body 4 is closed (namely, the right lower end part in fig. 1), and an exhaust hole for exhausting exhaust gas in the engine is formed in the exhaust pipe body 4; according to the engine exhaust structure, through the arrangement of the exhaust pipe body and the exhaust guide pipe, the power of the engine at a specific rotating speed is improved, fuel oil can be fully combusted, and the oil consumption is reduced; the structure is simple, and the weight of the exhaust pipe is reduced to the maximum extent; the direct discharge amount of unburned fuel is reduced.

In this embodiment, exhaust hole department connection is provided with exhaust pipe, has seted up exhaust hole department on blast pipe body 4, and corresponding exhaust hole position connection installation exhaust pipe 5 for discharge the inside waste gas of engine, blast pipe body 4 and exhaust pipe can adopt lightweight material such as titanium alloy, and light-weight demand is satisfied simultaneously to simple structure.

In this embodiment, an included angle α is formed between the exhaust duct 5 and the exhaust pipe body 4, and the included angle α is 85-90 °. The included angle between the exhaust duct 5 and the exhaust pipe body 4 is set to 90 degrees, so that exhaust gas can be discharged conveniently, and exhaust gas contacting the end part of the exhaust pipe body 4 can be rebounded back into the engine conveniently. The large-angle arrangement is adopted, so that most of air pressure can flow in the exhaust pipe body to form enough emission waves, and after the fresh air is back-pressed, the fresh air can be used as back pressure to prevent more fresh mixed air from overflowing in the next scavenging cycle.

In this embodiment, the distance between the exhaust duct 5 and the exhaust port of the engine is 1/4-1/3 of the length of the exhaust pipe body. As shown in fig. 1, this position ensures that a sufficient back pressure is created in the exhaust pipe body to prevent more mixture gas from escaping during the intake process.

In this embodiment, the exhaust pipe body 4 and the exhaust pipe 5 form a T-shaped structure.

A two-stroke engine having the above engine exhaust structure mounted thereon.

According to the engine structure, when the piston descends to a position C in the figure, the exhaust port is just opened, and high-temperature and high-pressure gas enters the exhaust pipe body in the form of pressure waves at a speed of a local Mach number related to the exhaust temperature; as the piston continues to descend (positions C-D), the in-cylinder pressure continues to drop and pressure wave release is complete; as the piston continues to move down (positions D to E) the engine enters a scavenging cycle, the scavenging air flow enters the exhaust pipe at a certain speed, and when moving to position E, the piston reaches bottom dead center; when the piston moves up to the position C, the first positive pressure wave discharged from the engine is reflected by the reflecting surface at the tail end of the exhaust pipe body 4 and just reflected to the exhaust port 3 (when passing through the exhaust port, the pressure wave carries part of the mixed gas to reenter the cylinder), and the actual effect is equivalent to the improvement of the impulse and the compression ratio of the inlet air.

In order to achieve the above effect, for the rated rotation speed S, the exhaust pipe length is calculated to achieve the pressure wave matching at the rotation speed, and the process is as follows:

exhaust temperature dependent local sonic velocity M;

pressure wave generation to exhaust port closing time: t= ((exhaust port closing angle B-exhaust port opening angle a)/360 °) (60/S); as shown in fig. 3;

it is required that the pressure wave reaches the exhaust port when the exhaust port is closed, i.e., the pressure wave reaches the exhaust port exactly when the time the pressure wave moves in the exhaust pipe is equal to T;

length of exhaust pipe: l=t×m×1000/2;

s is in rpm, M is in M/S, T is in S, and L is in mm.

The tube length is designed to be L through the calculation, and finally, the power optimal scheme of the engine at the rated rotating speed S is realized.

Finally, it is noted that the above embodiments are only for illustrating the technical solution of the present utility model and not for limiting the same, and although the present utility model has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the technical solution of the present utility model, which is intended to be covered by the scope of the claims of the present utility model.

Claims (5)

1. An engine exhaust structure, characterized in that: the exhaust pipe body is arranged at an exhaust port of the engine, the end part of the exhaust pipe body is closed, and an exhaust hole for exhausting waste gas in the engine is formed in the exhaust pipe body; the exhaust hole is connected with an exhaust duct.

2. The engine exhaust configuration according to claim 1, characterized in that: an included angle alpha is formed between the exhaust duct and the exhaust pipe body, and the included angle alpha is 85-90 degrees.

3. The engine exhaust configuration according to claim 1, characterized in that: the distance between the exhaust duct and the exhaust port of the engine is 1/4-1/3 of the length of the exhaust pipe body.

4. The engine exhaust configuration according to claim 1, characterized in that: the exhaust pipe body and the exhaust duct form a T-shaped structure.

5. A two-stroke engine, characterized by: the two-stroke engine having mounted thereon an engine exhaust configuration according to any one of the preceding claims 1-4.