KR100387718B1 - Changeable exhaust valve system of 2-stroke - Google Patents

Abstract

The present invention relates to an engine variable exhaust valve driving system of a two-stroke engine, comprising four first to four exhaust valves mounted on a cylinder head, and one to four opening / closing the first to fourth exhaust valves. 1st and 2nd camshafts provided with the 1st and 2nd cams and the 3rd and 4th cams which drive the 1st rocker arm, the 1st and 4th rocker arm individually, respectively, An exhaust valve drive system of a two-stroke engine, comprising: first and second pistons integrally formed at one end of each of the first and second camshafts; Accommodating the first and second pistons of the first and second camshafts so as to be rotatable and reciprocating, and at high speed of the engine, oil pressure is increased so that the first and second camshafts appear and operate. In addition, the invention is characterized by constituting the first and second oil pressure cylinders for immersing the first and second camshafts at low speed of the engine to optimize combustion of the two-stroke engine and to reduce fuel consumption and exhaust emission. .

Description

Changeable exhaust valve system of 2-stroke engine

The present invention relates to an engine variable exhaust valve drive system of two stroke engines.

In general, two-stroke engines, unlike four-stroke engines, do not have separate intake and exhaust strokes. That is, the intake process and the exhaust process occur simultaneously in the gas exchange or scavenging process.

Therefore, the gas exchange process in two administrations is much more complicated than the four administrations, and the hydrolysis process is the most important factor in determining efficiency and performance in the two administrations.

The two-stroke engine has a combustion consumption rate of about 30% lower than that of the four-stroke engine, the maximum brake mean effective pressure (BMEP) is about 17% higher (for gasoline engines), and weighs more than the four-stroke engine. It has the advantage of being lightweight.

In addition, the scavenging process in the two administrative agencies is a process of filling combustible gas or a mixture of air or fuel at the same time to discharge the combustible gas, such scavenging process has a number of systems such as cross-scavenging, loop scavenging, uniflosso.

Of the above two-stroke engine systems, what is needed for improved combustion when applied to diesel engines is that it needs to be properly controlled according to the speed so that the exhaust gas in the combustion chamber for intake exhaust amount and complete combustion can be properly released. By optimizing combustion, the goal is to improve fuel economy and minimize emissions.

In addition, since the mixture supply and the exhaust stroke are performed in a short time, fuel is discharged out like the exhaust, so that many unburned hydrocarbons are generated.

The present invention is to improve the exhaust system of the Uniflow 2 administration engine, which is the most suitable system for the above-mentioned diesel engine. In the diesel engine of the existing 4-stroke engine, the intake / exhaust amount is controlled through two intake / exhaust valves. The two-stroke Uniflow system engine, which is intended to be pursued by, installs four exhaust valves on the head of the engine and uses them for the exhaust stroke to release the exhaust gas by opening the valves at a constant opening amount in the load and RPM. In order to improve the distribution of unburned fuel in the emission of exhaust gas in the medium and low speed region, it is possible to effectively control the exhaust valve driving system according to the load and ALPM. As emissions, it is possible to optimize combustion and to suppress emissions of unburned hydrocarbons. It will leave a small invention.

The present invention as a means for achieving the above object,

Four exhaust valves 1 to 4 mounted on the head of the cylinder, rockers 1 to 4 for opening and closing the exhaust valves 1 to 4, and rockers 1 to 4 respectively. In an exhaust valve drive system of a two-stroke engine comprising: first and second camshafts each of which is driven by rotationally driven first and second drive cams and third and fourth drive cams, respectively.

First and second pistons integrally formed at one end of each of the first and second camshafts;

Accommodating the first and second pistons of the first and second camshafts so as to be rotatable and reciprocating, and at high speed of the engine, oil pressure is increased so that the first and second camshafts appear and operate. First and second oil pressure cylinders immersing the first and second camshafts at low speed of the engine;

It is characterized by consisting of

In addition, the first and second pistons accommodated in each of the first and second oil pressure cylinder is characterized in that the elastic support,

In addition, the width of the first cam of the first camshaft and the third cam of the second camshaft is narrow, the second cam of the first camshaft and the fourth cam of the second camshaft widen the width At high speed, the first to fourth rocker arms are rotated, while at the low speed, only the second and fourth rocker arms can be rotated without rotating the first and third rocker arms.

1 is a longitudinal cross-sectional view of a cylinder of a two-stroke engine for explaining the present invention.

Figure 2 is a plan view showing an exhaust valve arrangement of the present invention.

3 and 4 is a cam chart schematically shown to explain the present invention;

Operation state with rocker arm.

※ Explanation of code for main part of drawing

1 cylinder 11 cylinder head

12: scavenging hole 13: combustion chamber

14: piston

2a to 3d: 1 to 4 exhaust valve

3a to 3d: rockers 1 to 4

4a, 4b: first and second camshaft

41,42: first and second piston

5a to 5d: No. 1 to 4 drive cam

6a, 6b: first and second oil pressure cylinder

61,62 connector

7a, 7b: spring

An embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a longitudinal cross-sectional view of a cylinder of a two-stroke engine for explaining the present invention, FIG. 2 is a plan view showing an exhaust valve arrangement of the present invention, and FIGS. 3 and 4 are camshages schematically shown to explain the present invention. It shows the operation state of the trout and rocker arm,

Reference numeral 1 denotes a cylinder of two stroke engines, and four first to fourth exhaust valves 2a, 2b, 2c, and 2d are mounted on the upper portion of the cylinder 1, that is, the cylinder head 11. A plurality of scavenging holes 12 are formed at the bottom of the cylinder 1, and the piston 14 having the combustion chamber 13 formed on the upper surface of the cylinder 1 has a reciprocating operation up and down. It is possible.

In the present invention, only one cylinder 1 as described above is illustrated in the drawings, but two cylinders 1 are actually formed side by side.

Above the cylinder 1, the first and second rocker arms 3a and 3b for driving the first and second exhaust valves 2a and 2b, and the third and fourth exhaust valves 2c and 2d, respectively. 3 and 4 rocker arms (3c, 3d) are installed to drive the, and the rocker arms (3a, 3b) and 3 and 4 rockers (3c, 3d) First and second camshafts 4a and 4b for rotationally driving are provided.

The first camshaft 4a has a first drive cam 5a and a second drive cam 5b condensed to rotate the first rocker arm 3a and the second rocker arm 3b. In the second cam shaft 4b, the third drive cam 5c and the fourth drive cam 5d for driving each of the third rocker arm 3c and the fourth rocker arm 3d are condensed. have.

Each of the first and second driving cams 5a and 3c has a narrow width, and each of the second and second driving cams 5b and 4d has a wide width. have.

One end of each of the first and second cam shafts 4a and 4b rotates in the first and second oil pressure cylinders 6a and 6b in a state where the first pistons 41 and 42 are integrally formed. It is housed to be capable of reciprocating, and each of the first and second pistons 41 and 42 is elastically supported by springs 7a and 7b.

Each of the first and second oil pressure cylinders 6a and 6b is connected to the engine by connecting pipes 61 and 62, and when the engine is at high speed, the increased oil pressure is increased by the first and second oil. The first and second pistons 41 and 42 are pushed in opposite directions (right side in the drawing) while being introduced into the pressure cylinders 6a and 6b and elastically compressing the springs 7a and 7b. Accordingly, the first and second cam shafts 4a and 4b are also moved together, and in this case, the first to fourth driving cams 5a which are condensed to each of the first and second cam shafts 4a and 4b. , 5b, 5c, and 5d are all configured to rotate the rockers arm 3a, 3b, 3c, 3d from 1 to 4. (See Fig. 3).

Contrary to the above, when the engine is low speed, the oil pressure is lowered so that the elastic force of the springs 7a and 7b pushes the first and second pistons 41 and 42 to the left in the drawing. 2 Camshafts 4a and 4b are also moved to the left side. When the first and second camshafts are moved to the left side, drive cams 5a and 2 of the first camshaft 4a are moved. The third drive cam 5c of the camshaft 4b is prevented from rotating the first and third rocker arms 3a and 3c away from the first and third rocker arms 3a and 3c. The second drive cam 5b and the fourth drive cam 5d are configured to rotate the second and fourth rocker arms 3b and 3d. (See FIG. 4).

As described above, at the high speed of the engine, the first and second cam shafts 4a and 4b are moved to the right in the drawing as shown in FIG. 3 by the increased oil pressure. The first and second driving cams 5a and 5b and the third and fourth driving cams 5c and 5d which are respectively attached to the two camshafts 4a and 4b are respectively the first to fourth rocker arms ( Since 3a to 3d are driven to rotate, the four first to fourth exhaust valves 2a to 2d are fully open, and a large amount of exhaust gas can be emitted. The amount of unburned hydrocarbons is reduced.

Contrary to the above, at low speed of the engine, the oil pressure is lowered, and the first and second cam shafts 4a and 4b are moved to the left side as shown in FIG. 3 by the resilient elastic force of the springs 7a and 7b. 1 and 3 drive cams (5a) (5c) are confined to each camshaft, so the first and third rocker arms (3a) (3c) are narrow because the width is narrow, the first and third rockers described above The arm is prevented from rotating, but the 2nd and 4th drive cams (5b) (5d) are wide, so the 2nd and 4th rocker arms (3b) (3d) do not leave the 2nd and 4th rocker arms. In this case, the exhaust valves 2a and 2c are closed at the engine low speed, and only the exhaust valves 2b and 2d are opened. Although the space becomes smaller, the exhaust gas discharge rate is increased, which makes it possible to effectively discharge the exhaust gas, thereby reducing the amount of unburned hydrocarbons. .

Meanwhile, two driving cams respectively shown on the right side of the first and second cam shafts 4a and 4b in FIGS. 3 and 4 are not described, but they are not shown in another cylinder. By driving the exhaust valves mounted is the same operation as the drive cams 1 to 4 described above.

According to the present invention as described above, at low speed, only two exhaust valves of four exhaust valves are driven to reduce the exhaust space of the exhaust gas while increasing the discharge speed, and thus, the effective emission of the exhaust gas can be expected and unburned hydrocarbons. It has the effect of reducing the amount, and at high speed, all four exhaust valves can be exhausted to discharge a large amount of exhaust gas, and it is advantageous to reduce the pumping loss and unburned hydrocarbons due to the effective exhaust gas discharge. In general, the back pressure difference at low speed and high speed is large, but when the system of the present invention is applied, the back pressure difference at low speed and high speed is not largely generated. It can be supplied to reduce fuel consumption and exhaust emission through optimization of combustion. Will.

Claims (3)

Four exhaust valves 1 to 4 mounted on the head of the cylinder, rockers 1 to 4 for opening and closing the exhaust valves 1 to 4, and rockers 1 to 4 respectively. In an exhaust valve drive system of a two-stroke engine comprising: first and second camshafts each of which is driven by rotationally driven first and second drive cams and third and fourth drive cams, respectively. First and second pistons integrally formed at one end of each of the first and second camshafts; Accommodating the first and second pistons of the first and second camshafts so as to be rotatable and reciprocating, and at high speed of the engine, oil pressure is increased so that the first and second camshafts appear and operate. First and second oil pressure cylinders immersing the first and second camshafts at low speed of the engine; Configure but The width of the first cam of the first camshaft and the third cam of the second camshaft is narrow, and the second cam of the first camshaft and the fourth of cams of the second camshaft are wide at high speed. In the city, the first and fourth rocker arms are rotated, while at low speed, the two-stroke engines can rotate only the second and fourth rocker arms without rotating the first and third rocker arms. Engine variable exhaust valve drive system. delete delete