KR20220121298A - Changeable exhaust system of 2-stroke engine - Google Patents

Abstract

The present invention relates to a variable exhaust system for a two-stroke engine, which can improve performance of the two-stroke engine by forming high output in a wide range of revolutions per minute (rpm) by enabling a length of an exhaust pipe to be variably adjusted. The variable exhaust system for the two-stroke engine of the present invention comprises: a main pipe; a branch pipe; a variable valve; and a control unit.

Description

Variable exhaust system for 2-stroke engine {CHANGEABLE EXHAUST SYSTEM OF 2-STROKE ENGINE}

The present invention relates to a variable exhaust system for a two-stroke engine capable of improving the performance of a two-stroke engine by using the pulsation effect of exhaust gas.

In general, a two-stroke engine does not have an intake/exhaust valve structure unlike a four-stroke engine.

In such a two-stroke engine, the opening and closing of intake/exhaust ports formed on the side of the cylinder are adjusted according to the position of the piston. Accordingly, the pulsating effect of the exhaust gas is directly involved in the cylinder pressure and scavenging, and greatly affects the engine performance.

For reference, the pulsation effect refers to the effect that residual waves in the intake/exhaust pipe affect the intake/exhaust process of the next cycle.

Specifically, the conventional exhaust muffler for a two-stroke engine may be divided into a box (silencer) type and a tuned pipe type for each function.

Referring to FIG. 1 , the box (silencer) type has the main purpose of noise reduction, and the box capacity is the main factor. In addition, there is no exhaust pulsation effect, so the output is low, but the range of output fluctuation according to the revolutions per minute (rpm) is not large. This box (silencer) type is suitable for the limited package space as there is a limit to increase in performance.

Referring to FIG. 2 , the tuned pipe type is mainly aimed at maximizing performance, and the length of the pipe is a major factor. Such a tuned pipe type (hereinafter referred to as 'exhaust pipe') has a narrow range of revolutions per minute (rpm) in which the exhaust pulsation effect is maximized, and in sections other than the corresponding area, the pulsation causes an adverse effect, resulting in rapid performance degradation. can

Republic of Korea Patent Publication No. 10-2014-0141416 (published date: 2014.12.10.)

The present invention was devised to solve the above problems, and by enabling the length of the exhaust pipe to be variably adjusted, it is possible to improve the performance of a two-stroke engine by forming a high output in a wide rpm band. An object of the present invention is to provide a variable exhaust system for a two-stroke engine.

The variable exhaust system for a two-stroke engine according to the present invention for realizing the object as described above is provided with an inlet connected to the engine on one side so as to discharge exhaust gas generated from the engine to the outside, and an exhaust port on the other side a main pipe provided with a first flow path having a predetermined length; a branch pipe having one end connected to a point adjacent to the inlet of the main pipe, and the other end being extended by a predetermined length toward the outlet and then reconnected to the main pipe to form a second passage having a length longer than that of the first passage; a variable valve installed in the main pipe so as to be able to open and close and selectively open any one of the first flow path and the second flow path; and a control unit configured to control the variable valve to discharge the exhaust gas through any one of the first flow path and the second flow path.

In this case, the branch pipe may be spirally wound around the outer periphery of the main pipe.

In addition, the variable valve may include: a flap member having one side hinged to block any one of the first flow path and the second flow path and pivotally coupled within a predetermined angle range; and

It may include; an actuator for rotating the flap member.

In addition, the outer periphery of the flap member, a gasket for blocking the gap between the first flow passage or the second flow passage to maintain airtightness; may further include a provided.

In addition, on the inner peripheral surfaces of the first flow passage and the second flow passage, a locking protrusion may be formed to set an accurate sealing position when the flap member is turned.

In addition, the controller may control the variable valve based on the revolutions per minute (rpm) at which the pulsation effect of the first flow passage and the second flow passage transitions.

In the variable exhaust system for a two-stroke engine according to the present invention having the above configuration, any one of a main pipe having a first flow path and a branch pipe forming a second flow path is opened in a specific revolutions per minute (rpm) range. The pipe length can be variably adjusted, and accordingly, there is an advantage in that the performance of the two-stroke engine can be improved by forming a high output in a wide rpm band.

1 is a graph showing an exhaust pulsation maximization area of a Box (Silencer) type and a Tuned pipe type;
2 is a photograph for a drawing showing the appearance of a conventional Tuned pipe type;
3 is a perspective view showing a variable exhaust system for a two-stroke engine according to the present invention;
4 is a detailed view of part 'A' of FIG. 3 showing the internal structure of the variable valve according to the present invention;
5 to 7 are graphs showing the performance of the variable exhaust system for a two-stroke engine according to the present invention in various environmental conditions.

Hereinafter, the configuration and operation of specific embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Here, in adding reference numerals to the components of each drawing, it should be noted that only the same components are marked with the same reference numerals as much as possible even though they are displayed on different drawings.

3 is a perspective view showing a variable exhaust system for a two-stroke engine according to the present invention, and FIG. 4 is a detailed view of part 'A' of FIG. 3 showing the internal structure of the variable valve according to the present invention.

Referring to FIG. 3 , a variable exhaust system 100 for a two-stroke engine according to a preferred embodiment of the present invention includes a main pipe 110 , a branch pipe 120 , a variable valve 130 , a control unit (ECU, Mido). city) may be included.

The configuration of the present invention will be described in detail as follows.

First, the main pipe 110 is connected to the engine 10 , and may discharge exhaust gas generated when the engine 10 is operated to the outside. The main pipe 110 may have an inlet 111 connected to the engine 10 on one side and an outlet 113 on the other side to form a first flow path L1 of a predetermined length.

One side of the branch pipe 120 is connected to a point adjacent to the inlet 111 of the main pipe 110, and the other side is extended by a predetermined length toward the outlet 113 and then connected to the main pipe 110 again. can By including the branch pipe 120 branched from the main pipe 110 , when the exhaust gas moving through the inlet 111 is discharged to the outlet 113 through the branch pipe 120 , the first flow path A second flow path L2 having a length longer than that of L1 may be formed.

Specifically, the branch pipe 120 may be formed in a spirally wound shape around the outer periphery of the main pipe 110 . That is, as the branch pipe 120 should be formed within a limited length of the main pipe 110 without interfering with the flow of exhaust gas, it is preferable that the branch pipe 120 be wound in a spiral as described above.

That is, the length that affects the pulsation of the exhaust gas is the length (Lt) of the exhaust pipe. Accordingly, the branch pipe 120 is formed in the variable length adjusting unit L1, and the length Lt of the exhaust pipe is controlled by selectively opening and closing the branch pipe 120 to adjust the variable length adjusting unit L1. can

In this case, in the present invention, an example of the case where the branch pipe 120 is formed in a spiral has been shown and described, but while maintaining a smooth flow of exhaust gas, the main pipe 110 has a limited length and a predetermined length or more within the space. If it is a structure that can be formed, it can be changed and applied in various forms.

Referring to FIG. 4 , the variable valve 130 may be installed to be opened and closed inside the main pipe 110 . The variable valve 130 may selectively open any one of the first flow path L1 and the second flow path L2.

Specifically, the variable valve 130 is hinged at one side so as to block any one of the first flow path L1 and the second flow path L2 to seal it, and the flap member 131 is pivotally coupled within a predetermined angle range. ) and an actuator (not shown) for rotating the flap member 131 . In this case, since various types of actuators can be applied, the present invention is not particularly limited.

In addition, a gasket 133 may be provided on the outer periphery of the flap member 131 to maintain airtightness by blocking a gap between the flap member 131 and the first flow passage L1 or the second flow passage L2. The gasket may be formed of a material that can withstand a high temperature environment, and the material of the gasket 133 is not particularly limited.

In addition, a locking protrusion 135 may be provided on the inner circumferential surfaces of the first flow passage L1 and the second flow passage L2 so that an accurate sealing position can be set when the flap member 131 is turned.

The control unit (ECU, not shown) may control the flap member 131 of the variable valve 130 to swing to discharge the exhaust gas through any one of the first flow path L1 and the second flow path L2 .

In this case, since the control unit monitors the rpm of the engine in real time, the variable valve 130 may be controlled through the control unit.

The controller may control the variable valve 130 based on the revolutions per minute (rpm) to which the pulsation effect of the first flow passage L1 and the second flow passage L2 is transitioned.

In the variable exhaust system 100 for a two-stroke engine according to the present invention having the above configuration, the pulsating effect of exhaust gas generated in the length of the main pipe 110 in which the first flow path is formed is specific as shown in FIG. 5 . It can be maximized by limiting to the number of revolutions per minute (rpm) range. Accordingly, by variably adjusting the pipe length through the branch pipe 120 to open the second flow path, the performance of the two-stroke engine can be improved by forming high output in a wide rpm range. have.

Specifically, the exhaust system 100 of the two-stroke engine according to the present invention can maximize the output by generally using the C type among the three types shown in FIG. 6 .

In this case, the solid line graphs (blue, red, and green) shown on the right side of FIG. 6 are performance curves of the engine for each type of exhaust pipe, and the C type has the best performance, but the corresponding rpm range is narrow.

This effect changes the pulsation of the exhaust gas according to the position (length) of each shape of the C type exhaust pipe, which makes it easier to discharge the exhaust gas from the combustion chamber, thereby reducing the amount of exhaust gas remaining in the combustion chamber (Transfer effect). This is because it serves to prevent discharge through the exhaust pipe (plugging or port blocking effect).

Referring to FIG. 7 , in order to achieve the transfer and plugging effects, the exhaust port pressure becomes a side job before and after BDC, so that the exhaust gas must be well discharged from the combustion chamber, and the pressure between the BDC and intake air closing It must be plugged (plugging) so that the new air flowing into the combustion chamber at this positive pressure is not discharged to the exhaust port.

That is, in the 2-stroke engine, the intake and exhaust ports are in the form of holes next to the cylinder bore, and the intake/exhaust port holes are opened and closed according to the position of the piston, and the intake is always open while the exhaust is open. Accordingly, if the exhaust gas is not well discharged, the fresh air cannot smoothly enter the combustion chamber, and even if the fresh air enters the combustion chamber, the exhaust port is open, so that the fresh air may be directly discharged to the exhaust side.

In the above, the present invention has been illustrated and described with reference to specific specific embodiments, but the present invention is not limited to the above-described embodiments, and various changes and modifications are possible without departing from the technical spirit of the present invention.

10: engine 100: variable exhaust system
110: main pipe 111: inlet
113: outlet L1: first flow path
L2: 2nd Euro 120: Branch pipe
130: variable valve 131: flap member
133: gasket 135: hooking jaw

Claims (6)

a main pipe having an inlet connected to the engine on one side to discharge exhaust gas generated from the engine to the outside, and an outlet port on the other side to form a first flow path of a predetermined length;
a branch pipe having one end connected to a point adjacent to the inlet of the main pipe, and the other end being extended by a predetermined length toward the outlet and then reconnected to the main pipe to form a second passage having a length longer than that of the first passage;
a variable valve installed in the main pipe so as to be able to open and close and selectively open any one of the first flow path and the second flow path; and
and a control unit configured to control the variable valve to discharge the exhaust gas through any one of the first flow path and the second flow path.
According to claim 1,
The branch pipe is
A variable exhaust system for a two-stroke engine that is formed in a spirally wound shape around the outer periphery of the main pipe.
According to claim 1,
The variable valve is
a flap member having one side hinged to block any one of the first flow path and the second flow path and pivotally coupled within a predetermined angle range; and
A variable exhaust system for a two-stroke engine comprising a; an actuator for rotating the flap member.
4. The method of claim 3,
On the outer periphery of the flap member,
A variable exhaust system for a two-stroke engine further comprising a gasket for maintaining airtightness by blocking a gap between the first flow path or the second flow path.
4. The method of claim 3,
On the inner peripheral surfaces of the first flow path and the second flow path,
The variable exhaust system for a two-stroke engine further comprising a locking jaw so that an accurate sealing position can be set when the flap member is turned.
According to claim 1,
The control unit is
and controlling the variable valve based on revolutions per minute (rpm) at which the pulsation effect of the first flow passage and the second flow passage transitions.

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