KR102643883B1 - Changeable exhaust system of 2-stroke engine - Google Patents

Abstract

The present invention relates to a variable exhaust system for a two-stroke engine that improves the performance of the two-stroke engine by generating high output in a wide range of revolutions per minute (rpm) by allowing the length of the exhaust pipe to be variably adjusted. .

Description

{CHANGEABLE EXHAUST SYSTEM OF 2-STROKE ENGINE}

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

Generally, 2-stroke engines do not have an intake/exhaust valve structure, unlike 4-stroke engines.

In these two-stroke engines, the opening and closing of intake/exhaust ports formed on the side of the cylinder is adjusted depending on the piston position. Accordingly, the pulsation effect of exhaust gas is directly involved in cylinder pressure and scavenging and has a significant impact on engine performance.

For reference, the pulsation effect refers to the effect of residual waves within the intake/exhaust pipe affecting the intake and exhaust process of the next cycle.

Specifically, conventional exhaust mufflers for two-stroke engines can be divided into box (silencer) type and tuned pipe type according to function.

Referring to Figure 1, the Box (Silencer) type is mainly aimed at reducing noise, with box capacity as the main factor. In addition, there is no exhaust pulsation effect, so the output is low, but the range of output fluctuation according to revolutions per minute (rpm) is not large. This Box (Silencer) type has limited performance increase and is therefore suitable for limited package space.

Referring to Figure 2, the Tuned pipe type is mainly aimed at maximizing performance, and the length of the pipe is the main factor. This Tuned pipe type (hereinafter referred to as 'exhaust pipe') has a narrow range of revolutions per minute (rpm) where the exhaust pulsation effect is maximized, and in sections other than this area, the pulsation causes adverse effects, leading to a rapid decrease in performance. You can.

The above-described background technology is technical information that the inventor possessed for deriving the embodiments of the present invention or acquired during the derivation process, and cannot necessarily be said to be known technology disclosed to the general public before the application for the embodiments of the present invention. does not exist.

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

The present invention was developed to solve the above-mentioned problems, and by allowing 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 range of revolutions per minute (rpm). The purpose is to provide a variable exhaust system for two-stroke engines.

However, the problem to be solved by the present invention is not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description.

The variable exhaust system for a two-stroke engine according to the present invention for realizing the above-described purpose is provided with an inlet connected to the engine on one side to discharge exhaust gas generated from the engine to the outside, and an outlet on the other side. A main pipe that is provided and forms a first flow path of a predetermined length; A branch pipe in which one side of the branch inlet is connected to a point adjacent to the inlet of the main pipe, the other side extends a predetermined length toward the outlet, and then the branch outlet is reconnected to the main pipe to form a second flow path that is longer than the first flow path. ; A variable valve installed to be openable and closed inside the main pipe to selectively open either the first flow path or the second flow path; and a control unit that controls the variable valve to discharge the exhaust gas through either the first flow path or the second flow path. The diameter of the branch outlet in the branch pipe may be formed according to a mathematical equation.

[Equation]

From here, is the diameter of the branch outlet, is the diameter of the main pipe at the part where one side of the branch inlet of the branch pipe is connected, is the diameter of the main pipe at the part where the other side of the branch outlet of the branch pipe is connected, is the length of the main pipe from the part where one side of the branch inlet of the branch pipe is connected to the other side of the branch outlet, means the length of the branch pipe.

Here, the branch inlet of the branch pipe may be formed to have a diameter equal to the diameter of the main pipe at the part where one side of the branch inlet is connected to the main pipe.

Additionally, the branch pipe may be formed in a spiral shape wound around the outer circumference of the main pipe.

In addition, the variable valve includes a flap member that is hinged on one side and pivotable within a predetermined angle range to block and seal either the first flow path or the second flow path; and an actuator that rotates the flap member.

In addition, the outer circumference of the flap member may further include a gasket that closes the gap between the first flow path and the second flow path to maintain airtightness.

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

Additionally, the control unit may control the variable valve based on the number of revolutions per minute (rpm) at which the pulsation effect of the first flow path and the second flow path transitions.

The variable exhaust system for a two-stroke engine according to the present invention configured as described above opens one of the main pipe forming the first flow path and the branch pipe forming the second flow path in a specific revolutions per minute (rpm) range. The pipe length can be variably adjusted, which has the advantage of improving the performance of a two-stroke engine by producing high output in a wide range of revolutions per minute (rpm).

Here, even if the length of the flow path through which exhaust gas is discharged from the main pipe to the branch pipe changes, the rate of change in cross-sectional area according to the change in length is the same, so higher output can be generated in a wide rpm range.

The effects that can be obtained from the invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. .

Figure 1 is a graph showing the exhaust pulsation maximization area of the box (silencer) type and the tuned pipe type.
Figure 2 is a photograph showing the appearance of a conventional tuned pipe type,
Figure 3 is a perspective view showing a variable exhaust system for a two-stroke engine according to the present invention;
Figure 4 is a detailed view of part 'A' of Figure 3 showing the internal structure of the variable valve according to the present invention;
Figure 5 is a cross-sectional view showing a variable exhaust system for a two-stroke engine according to the present invention;
6 to 8 are graphs showing the performance of the variable exhaust system for a two-stroke engine according to the present invention under various environmental conditions.

The present invention will become clear by referring to the embodiments described in detail below along with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below and will be implemented in various different forms. These embodiments only serve to ensure that the disclosure of the present invention is complete, and those skilled in the art It is provided to fully inform the person of the scope of the invention, and the present invention is only defined by the scope of the claims. Meanwhile, the terms used in this specification are for describing embodiments and are not intended to limit the present invention.

Throughout this specification, singular forms include plural forms, unless the context clearly dictates otherwise.

Throughout this specification, “comprises” and/or “comprising” refers to a referenced component, step, operation and/or element that includes one or more other components, steps, operations and/or elements. The presence or addition of elements is not excluded, which means that other components may be further included rather than excluding other components unless specifically stated to the contrary.

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

Here, in adding reference numerals to components in each drawing, it should be noted that identical components are indicated with the same reference numerals as much as possible, even if they are shown in different drawings.

Figure 3 is a perspective view showing a variable exhaust system for a two-stroke engine according to the present invention, Figure 4 is a detailed view of the 'A' portion of Figure 3 showing the internal structure of the variable valve according to the present invention, and Figure 5 is a detailed view of the variable exhaust system for a two-stroke engine according to the present invention. This is a cross-sectional view showing a variable exhaust system for a two-stroke engine.

Referring to FIG. 3, the 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, and a control unit (ECU). Poetry) may be included.

A detailed description of the configuration of the present invention is as follows.

First, the main pipe 110 is connected to the engine 10 and can discharge exhaust gas generated during operation of the engine 10 to the outside. This main pipe 110 is provided with an inlet 111 connected to the engine 10 on one side and an outlet 113 on the other side, thereby forming a first flow passage L1 of a predetermined length.

The branch pipe 120 has one side of the branch inlet connected to a point adjacent to the inlet 111 of the main pipe 110, and the other side extends a predetermined length toward the outlet 113, and then the branch outlet is returned to the main pipe 110. It can be formed in a connected way. By including a 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 It is possible to form a second flow path (L2) that is longer than (L1).

Here, in order to produce high output in a wide range of revolutions per minute (rpm), the diameters of the inlet and outlet can be appropriately designed according to the lengths of the main pipe 110 and the branch pipe 120. Specifically, referring to Figure 5, it can be seen that the length and diameter of each part of the variable exhaust system 100 are shown.

In particular, LP12, in the present invention, refers to the length of the flow path portion that changes as the variable valve 130 is selectively opened and closed when the exhaust gas generated from the engine 10 is discharged to the outside. That is, it represents the length of the main pipe 110, or the length of the branch pipe 120, from the part where one side of the branch inlet is connected to the part where the other side of the branch outlet is connected.

DEP1 and DEP2 refer to the diameters of the inlet and outlet of the changing flow path. Specifically, in the main pipe 110, DEP1 is the diameter of the main pipe at the part where one side of the branch inlet of the branch pipe 120 is connected, and DEP2 is the diameter of the main pipe at the part where the other side of the branch outlet of the branch pipe 120 is connected. it means. Meanwhile, in the branch pipe 120, DEP1 refers to the diameter of the branch inlet, and DEP2 refers to the diameter of the branch outlet.

Accordingly, the diameter of the branch outlet in the branch pipe 120 according to a preferred embodiment of the present invention can be formed according to the equation below.

[Equation]

From here, is the diameter of the branch outlet, is the diameter of the main pipe at the part where one side of the branch inlet of the branch pipe 120 is connected, is the diameter of the main pipe at the part where the other side of the branch outlet of the branch pipe 120 is connected, is the length of the main pipe from the part where one side of the branch inlet of the branch pipe 120 is connected to the other side of the branch outlet, means the length of the branch pipe 120.

In addition, the diameter of the branch inlet of the branch pipe 120 ( ) is the main pipe 110 and the diameter ( ) can be formed in the same way as. This means that even if the variable valve 130 is controlled to discharge exhaust gas through either the first flow path (L1) or the second flow path (L2), the exhaust gas flows into the main pipe 110 or the branch pipe 120. The diameters of the parts are meant to be the same.

In Table 1 and Table 2 below, it can be seen that the length and diameter of each part of the variable exhaust system 100 according to an embodiment are described. In particular, Table 1 shows the configuration in which exhaust gas is discharged through the main pipe 110, and Table 2 shows the configuration in which exhaust gas is discharged through the branch pipe 120.

Length (mm) LP01 100 LP12 400 L1 LP23 140 LP34 110 LP45 240 LP56 240 Cross section diameter (mm) DEP1 23 D1 DEP2 35 D2 DEP3 50 DEP5 16

Length (mm) LP01 100 LP12' 500 L2 LP23 140 LP34 110 LP45 240 LP56 240 Cross section diameter (mm) DEP1 23 D3 DEP2' 38 D DEP3 50 DEP5 16

In Table 1, LP12 is the length of the main pipe 110 from the part where one side of the branch inlet of the branch pipe 120 is connected to the other side of the branch outlet ( ), and DEP1 is the diameter of the main pipe at the part where one side of the branch inlet of the branch pipe 120 is connected ( ), and DEP2 is the diameter of the main pipe at the part where the other side of the branch outlet of the branch pipe 120 is connected ( ).

In Table 2, LP12' refers to the length of the branch pipe 120 ( ), and DEP1 is the branch inlet diameter ( ), and DEP2' is the diameter of the branch outlet ( ).

In particular, in one embodiment of the present invention, the diameter of the branch inlet ( ) and the diameter of the main pipe ( ) was formed in the same way.

Here, the diameter of the branch outlet ( ) is derived as follows when calculated according to the equation.

Ultimately, the diameter of the branch outlet ( ) is formed according to the above results, even if the length of the passage through which exhaust gas is discharged from the main pipe 110 to the branch pipe 120 changes, the rate of change in cross-sectional area according to the change in length is the same, so it can be used in a wide rpm range. It has the effect of producing higher output.

Meanwhile, the branch pipe 120 may be formed in a spiral shape wound around the outer circumference of the main pipe 110. That is, since the branch pipe 120 must be formed within a limited length of the main pipe 110 without interfering with the flow of exhaust gas, it is preferably formed by winding it in a spiral shape as described above.

In other words, the length that affects the pulsation of the exhaust gas is the length (Lt) of the exhaust pipe. Accordingly, the length (Lt) of the exhaust pipe can be controlled by forming a branch pipe (120) in the variable length control part (L1) and controlling the variable length control part (L1) by selectively opening and closing the branch pipe (120). You can.

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

Referring to FIG. 4, the variable valve 130 may be installed inside the main pipe 110 to be open and closed. This variable valve 130 can selectively open either the first flow path (L1) or the second flow path (L2).

Specifically, the variable valve 130 is a flap member 131 that is hinged on one side and pivotable within a predetermined angle range so as to block and seal either the first flow path (L1) or the second flow path (L2). ) and an actuator (not shown) that rotates 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 circumference of the flap member 131 to close the gap between the first flow path (L1) or the second flow path (L2) to maintain airtightness. The gasket may be made of a material that can withstand a high temperature environment, and the material of the gasket 133 is not particularly limited.

Additionally, a locking protrusion 135 may be provided on the inner peripheral surface of the first flow passage L1 and the second flow passage L2 to set an accurate sealing position when the flap member 131 rotates.

The control unit (ECU, not shown) may control the swing of the flap member 131 of the variable valve 130 to discharge exhaust gas through either the first flow path (L1) or 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 can be controlled through the control unit.

This control unit can control the variable valve 130 based on the revolutions per minute (rpm) at which the pulsation effect of the first flow path (L1) and the second flow path (L2) transitions.

In the variable exhaust system 100 for a two-stroke engine according to the present invention configured as described above, the pulsation effect of the exhaust gas occurring in the length of the main pipe 110 in which the first flow path is formed is specific as shown in FIG. 6. It can be maximized by limiting it to the revolutions per minute (rpm) range. Accordingly, the pipe length can be variably adjusted through the branch pipe 120 to open the second flow path, thereby improving the performance of the two-stroke engine by generating high output in a wide range of revolutions per minute (rpm). there is.

Specifically, the exhaust system 100 of a two-stroke engine according to the present invention can maximize output by generally using the C type among the three types shown in FIG. 7.

In this case, the solid line graph (blue, red, green) shown on the right side of FIG. 7 is the engine performance curve for each exhaust pipe type, and the C type has the best performance, but the corresponding rpm range is narrow.

This effect changes the pulsation of exhaust gas depending on the position (length) of each shape of the C-type exhaust pipe, making it easier to discharge exhaust gas from the combustion chamber, reducing the amount of exhaust gas remaining in the combustion chamber (transfer effect), and also reducing the amount of new air entering the combustion chamber. This is because it plays a role in preventing discharge through the exhaust pipe (plugging or port blocking effect).

Referring to FIG. 8, in order to achieve the transfer and plugging effects, the exhaust port pressure before and after BDC must be sidelined to properly transfer the exhaust gas from the combustion chamber, and the pressure between BDC and intake closure must be maintained. This positive pressure must be plugged to prevent the fresh air flowing into the combustion chamber from being discharged through the exhaust port.

That is, in a two-stroke engine, the intake and exhaust ports are in the form of holes next to the cylinder bore, and the intake and exhaust port holes open and close depending on the piston position, and the intake is always open while the exhaust is open. Accordingly, if the exhaust gas is not discharged properly, the fresh air cannot enter the combustion chamber smoothly, and even if the fresh air enters the combustion chamber, it can be discharged directly to the exhaust side because the exhaust port is open.

In the above, the present invention has been shown 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 can be made 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: Second Euro 120: Branch pipe
130: variable valve 131: flap member
133: Gasket 135: Locking jaw
: Diameter of branch outlet
: The diameter of the main pipe at the part where one side of the branch inlet of the branch pipe is connected.
: The diameter of the main pipe at the part where the other side of the branch outlet of the branch pipe is connected.
: The length of the main pipe from the part where one side of the branch inlet of the branch pipe is connected to the part where the other side of the branch outlet is connected.
: Length of branch pipe

Claims (7)

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 on the other side to form a first flow path of a predetermined length;
One side of the branch inlet is connected to a point adjacent to the inlet of the main pipe, and the other side is extended a predetermined length toward the outlet, and then the branch outlet is reconnected to the main pipe to form a second flow path longer than the first flow path. forming branch pipes;
A variable valve installed to be openable and closed inside the main pipe to selectively open one of the first flow path and the second flow path; and
A control unit that controls the variable valve to discharge the exhaust gas through one of the first flow path and the second flow path,
A variable exhaust system for a two-stroke engine, wherein the diameter of the branch outlet in the branch pipe is formed according to a mathematical equation.

[Equation]


From here, is the diameter of the branch outlet, is the diameter of the main pipe at the part where one side of the branch inlet of the branch pipe is connected, is the diameter of the main pipe at the part where the other side of the branch outlet of the branch pipe is connected, is the length of the main pipe from the part where one side of the branch inlet of the branch pipe is connected to the part where the other side of the branch outlet is connected, means the length of the branch pipe.
According to paragraph 1,
The branch inlet of the branch pipe is,
A variable exhaust system for a two-stroke engine, wherein the portion where one side of the branch inlet is connected to the main pipe is formed with a diameter equal to the diameter of the main pipe.
According to paragraph 1,
The branch pipe is,
A variable exhaust system for a two-stroke engine, which is formed in a spirally wound shape around the outer circumference of the main pipe.
According to paragraph 1,
The variable valve is,
a flap member that is hinged on one side and pivotable within a predetermined angle range to block and seal any one of the first flow path and the second flow path; and
A variable exhaust system for a two-stroke engine including an actuator that rotates the flap member.
According to paragraph 4,
On the outer circumference of the flap member,
A variable exhaust system for a two-stroke engine, further comprising a gasket that closes the gap between the first flow path and the second flow path to maintain airtightness.
According to paragraph 4,
On the inner peripheral surface of the first flow path and the second flow path,
A variable exhaust system for a two-stroke engine further comprising a locking protrusion so as to set an accurate sealing position when the flap member rotates.
According to paragraph 1,
The control unit,
A variable exhaust system for a two-stroke engine that controls the variable valve based on the revolutions per minute (rpm) at which the pulsation effect of the first flow path and the second flow path transitions.