KR101219622B1 - Homogeneous charge compression ignition type two strokes engine - Google Patents

Abstract

According to one embodiment of the invention the premixed compression self-ignition two-stroke engine includes a piston; A cylinder having a combustion chamber located above the piston; An intake port connected to the cylinder to allow outside air to flow and an exhaust port connected to the cylinder to discharge combustion gas inside the combustion chamber; A crankshaft installed at a lower portion of the cylinder and connected to the piston by a connecting rod and connected to the intake port; An injector for injecting fuel into the combustion chamber to induce self ignition; And an exhaust valve installed on the exhaust port and opening and closing the exhaust port.

Description

Premixed Compression Self-ignition Two-stroke Engine {HOMOGENEOUS CHARGE COMPRESSION IGNITION TYPE TWO STROKES ENGINE}

The present invention relates to a premixed compression self-ignition type two-stroke engine, and more particularly to a premixed compression self-ignition type two-stroke engine that is self-ignition combustion by compression.

Homogeneous Charge Compression Ignition (HCCI) engines do not use spark plugs like regular gasoline engines or self-ignition by compression heat like general diesel engines. Is the engine of the way.

Premixed compression ignition type engines have higher thermal efficiency than diesel engines as well as good fuel consumption, and there is no knocking problem, which is one of the problems of gasoline engines. In addition, emissions such as HC and NOx contained in a large amount in the exhaust gas are significantly reduced.

1 is a view showing the ignition by the spark plug in a general gasoline engine, Figure 2 is a view showing the magnetization made in the premixed compression self-ignition engine. In the case of a normal gasoline engine, ignition plug is ignited and combusted, and this causes not only abnormal combustion and knocking, but also misfire, unburned combustion, or HC. In contrast, in the case of the premixed compression ignition engine, combustion is performed by magnetization, and not only high efficiency is possible due to stable combustion, but also HC and NOx can be reduced.

Premixed compression self-ignition engine having many advantages as described above has a problem that the operating range is severely limited in the high load and low load region.

An object of the present invention is to provide a premixed compression self-ignition two-stroke engine capable of magnetizing combustion.

Another object of the present invention is to provide a premixed compression self-ignition two-stroke engine that can not only improve thermal efficiency, but also significantly reduce emissions such as HC and NOx.

Still other objects of the present invention will become more apparent from the following detailed description and the accompanying drawings.

According to one embodiment of the invention the premixed compression self-ignition two-stroke engine includes a piston; A cylinder having a combustion chamber located above the piston; An intake port connected to the cylinder to allow outside air to flow and an exhaust port connected to the cylinder to discharge combustion gas inside the combustion chamber; A crankshaft installed at a lower portion of the cylinder and connected to the piston by a connecting rod and connected to the intake port; An injector for injecting fuel into the combustion chamber to induce self ignition; And an exhaust valve installed on the exhaust port and opening and closing the exhaust port.

The exhaust valve may partially close the exhaust port after the self ignition occurs in the combustion chamber to partially block the exhaust through the exhaust port.

After the self ignition occurs in the combustion chamber, the opening degree of the exhaust valve may be -25%.

When the opening angle of the exhaust valve is -25%, the opening area of the exhaust port may be ² cm ² .

The injector may inject fuel at 270deg.ATDC.

The injector may be arranged such that the ejection port is inclined with respect to the moving axis connecting the inside of the crank case and the combustion chamber with respect to the center axis of the cylinder.

The inclination angle of the injector may be 25 degrees to 40 degrees.

Self-ignition conditions of the engine may be the engine speed of 1500rpm.

According to the present invention, power can be obtained by causing self-ignition combustion in the cylinder, and in particular, the thermal efficiency can be improved, and emissions such as HC and NOx can be significantly reduced.

1 is a view showing the ignition by the spark plug in a general gasoline engine.
Fig. 2 is a diagram showing magnetization performed in the premixed compression ignition engine.
3 is a view schematically showing a premixed compression ignition type two-stroke engine according to an embodiment of the present invention.
4 and 5 are views showing the state of opening and closing the exhaust port through the exhaust valve shown in FIG.
FIG. 6 is a view showing an injection timing of the injector shown in FIG. 3.
7 to 11 are photographs showing fuel distribution and temperature distribution in the cylinder according to various experimental conditions.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to FIGS. 1 to 11. The embodiments of the present invention can be modified in various forms, and the scope of the present invention should not be construed as being limited to the embodiments described below. The embodiments are provided to explain the present invention to a person having ordinary skill in the art to which the present invention belongs. Accordingly, the shape of each element shown in the drawings may be exaggerated to emphasize a clearer description.

3 is a view schematically showing a premixed compression ignition type two-stroke engine according to an embodiment of the present invention. The engine includes a cylinder 10 and a piston 20, the piston 20 moves up and down inside the cylinder 10. The cylinder 10 has a combustion chamber 12 provided above the piston 20, and the injector 35 described later injects fuel into the combustion chamber 12. The injected fuel is burned by self-ignition.

As shown in FIG. 3, the engine further includes a connecting rod 42 and a crankshaft 44, and the piston 20 is connected to the crankshaft 44 through the connecting rod 42. One end of the connecting rod 42 is rotatably connected to the piston 20, and the other end of the connecting rod 42 is eccentrically connected to the crankshaft 44 so as to be rotatable. When the crankshaft 44 rotates, the connecting rod 42 moves up and down, and the piston 20 connected to one end of the connecting rod 42 also moves up and down to compress the outside air and fuel introduced into the combustion chamber 12. As the crankshaft 44 rotates, the piston 20 reciprocates up and down within the cylinder 10. The engine operates in a two-stroke cycle, and the piston 20 reciprocates two strokes-one revolution as the crankshaft 44 makes one revolution. The crankshaft 44 is installed in the crankcase 41 and rotatable, and the crankcase 41 is located below the cylinder 10.

The engine has an exhaust port 32, an intake port 34, and a transfer port 38. The exhaust port 32 is disposed at one side of the cylinder 10 and connected to the combustion chamber 12, and the combustion gas generated in the combustion chamber 12 is discharged through the exhaust port 32.

The exhaust valve 36 is provided on the exhaust port 32, and opens and closes the exhaust port 32 by rotation. According to the two-stroke cycle, when combustion occurs in the combustion chamber 12, the piston 20 is lowered, which causes the exhaust port 32 to be opened so that the combustion gas inside the combustion chamber 12 is connected to the exhaust port 32. Is discharged through. At this time, the exhaust valve 36 reduces the open area of the exhaust port 32, thereby preventing the exhaust gas generated in the combustion chamber 12 from being smoothly discharged, thereby being included in the combustion gas to exhaust the exhaust port 32. By recovering the heat that is just released through it, by using the newly supplied mixer to the gasoline magnetization temperature (about 1800K) it is possible to self-ignite the gasoline at the compression ratio of the normal gasoline engine. This is called the "intake heat effect". In particular, in the two-stroke engine, since a large amount of exhaust gas remains in the combustion chamber 12 after combustion, the mixer can be easily heated using the exhaust gas. Detailed description of the exhaust port 32 and the exhaust valve 36 will be described later.

The intake port 34 is disposed on the other side of the cylinder 10 and connected to the inside of the crankcase 41. Outside air is introduced through the intake port 34 and filled in the crankcase 41. As the piston 20 descends, the outside air inside the crankcase 41 moves to the combustion chamber 12. The moving port 38 connects the inside of the crankcase 41 and the combustion chamber 12, and the outside air moves to the combustion chamber 12 through the moving port 38.

The engine further includes an injector 35, which injects fuel into the combustion chamber 12. The injector 35 injects fuel at an injection angle of approximately 55 °, and the injected fuel can be burned by self-ignition. As shown in FIG. 3, the injector 35 may be disposed to be inclined at an angle θ with respect to the central axis of the cylinder 10, and the ejection opening of the injector 35 may face the upper end of the moving port 38. It may be arranged to. Detailed description thereof will be described later.

4 and 5 are views showing the opening and closing of the exhaust port 32 through the exhaust valve 36 shown in FIG. As described above, the exhaust valve 36 may selectively open and close the exhaust port 32, and as shown in FIGS. 4 and 5, according to a valve angle ratio (VAR) of the exhaust valve. The exhaust port 32 has a different open area. As shown in FIGS. 4 and 5, when the opening area 13cm ² of the exhaust port 32 is equal to the cross-sectional area of the exhaust port 32, VAR = 100%, and the opening area of the exhaust port 32 is 3cm. ^{2 means} VAR = 0%. In the case where the opening area of the exhaust port 32 is (13 cm ² ), VAR = -25%. In other words, the exhaust valve 36 can selectively open and close the exhaust port 32 according to the rotational angle, and the opening angle is The opening area of the exhaust port 32 is changed accordingly.

FIG. 6 is a view showing an injection timing of the injector shown in FIG. 3. The horizontal axis means a crank angle (rotation angle of the crank shaft 44), and means a top dead center (TDC) when the crank angle is 0 (or 360). In addition, the blue line represents the pressure change inside the combustion chamber 12. As shown in FIG. 6, the pressure value inside the combustion chamber 12 reaches a maximum value after the crank angle slightly exceeds 0 (or top dead center). Have

The red bar indicates the degree of closure of the exhaust port 32 by the piston 20, and it can be seen that the exhaust port 32 starts to open at 87deg.ATDC (100% closure rate) and opens up to 273deg.ATDC. . It can be seen that the exhaust port 32 is fully open (0% closure rate) at 180 deg. ATDC. The blue bar indicates the degree of closure of the moving port 38 (or the top of the moving port 38) by the piston 20, and the moving port 38 begins to open at 125 deg. ATDC (100% closure rate) You can see that it opens up to 235deg.ATDC. It can be seen that the moving port 38 is completely open (0% closure rate) at 180deg.ATDC. The opening / closing timing of the exhaust port 32 and the moving port 38 is determined according to the positions of the exhaust port 32 and the moving port 38 shown in FIG.

As shown in FIG. 6, the injector 35 may selectively inject fuel into the combustion chamber 12 according to the crank angle. For example, the injector 35 may inject fuel at 180 deg. ATDC. Fuel can be injected at 273deg.ATDC. The fuel injected by the injector 35 into the combustion chamber 12 according to the crank angle is distributed in various forms. Detailed description thereof will be described later.

7 to 10 are photographs showing fuel distribution and temperature distribution in the cylinder according to various experimental conditions.

Looking at the left picture of Fig. 7, 1500r / min, VAR = 0%, IT (injection time) = 270deg. In the case of ATDC, it can be seen that stratification is progressing due to a large difference in concentration between the mixer (mixing of outside air moved to the combustion chamber 12 through the moving port 38 and fuel injected through the injector 35). On the other hand, looking at the left picture of Figure 8, 1500r / min, VAR = -25%, IT = 180deg. In the case of ATDC, it can be seen that the concentration difference of the mixer in the combustion chamber 12 is substantially reduced.

In addition, when looking at the right photograph of FIG. 7, the temperature in the combustion chamber 12 is distributed in a wide range, and it shows the nonuniform temperature range, while looking at the right photograph of FIG. 8, uniformity of a mixer is advanced, Since the high temperature range in a cylinder is wide, it turns out that it satisfy | fills the conditions which enable self-ignition combustion.

In addition, as shown in Fig. 9, 1500 r / min, VAR = -25%, IT = 270 deg. As a result of testing the occurrence of magnetization in the state of ATDC, it was found that the temperature in the combustion chamber 12 became the ignition temperature and the fuel in the combustion chamber 12 was also widely distributed. However, in the state shown in FIG. 7 (1500 r / min, VAR = 0%, IT = 270 deg. ATDC), self ignition was not performed because the total temperature was very low.

As a result of the above experiment, in the case of the compression self ignition according to the late injection timing, the high temperature sparse region and the low temperature and the concentrated region exist in the combustion chamber 12, and the flame propagation is possible in the low temperature and the concentrated region. Since the conditions were satisfied, it was found that flame propagation occurred after self-ignition of the high temperature lean region. In addition, when VAR = 0%, the self-ignition was not performed because the total temperature was low, but when VAR = -25%, self-ignition was made.

As described above, the injector 35 may be disposed to be inclined at a predetermined angle θ, and may inject fuel into the combustion chamber 12 in an inclined state. FIG. 10 shows fuel distribution and temperature distribution when 1500r / min, VAR = -25%, IT = 270deg.ATDC, θ = -40 °, FIG. 11 shows 1500r / min, VAR = -25%, IT = 270deg ATDC, θ = 40 ° shows fuel distribution and temperature distribution.

Referring to FIGS. 10 and 11, when θ = 40 °, self-ignition sufficiently occurs because the fuel-rich side and the high temperature distribution region are well distributed in the combustion chamber 12 and the fuel is widely distributed in the combustion chamber 12. Of course, even when θ = -40 °, the thin side of the fuel and the high temperature distribution region are distributed, so that the self ignition occurs, and the self ignition operation may be performed by the combustion of flame propagation after the self ignition occurs. However, when θ = 40 °, the rich side and the high temperature distribution area of the fuel are well distributed and wider. Therefore, when θ = 40 °, it is a condition that self ignition is likely to occur. In addition, in the case of FIG. 9 described above, since θ = 25 ° and the same distribution as that of FIG. 11, it can be seen that autoignition occurs easily at θ = 25 ° to 40 °.

Although the present invention has been described in detail by way of preferred embodiments thereof, other forms of embodiment are possible. Therefore, the technical idea and scope of the claims set forth below are not limited to the preferred embodiments.

Meanwhile, in the present embodiment, only the combustion by the self ignition method has been described. Alternatively, the combustion by the self ignition method and the combustion by the spark ignition method may be used in combination. That is, in the operation region in which combustion by the self ignition method is difficult, combustion by the spark ignition method may be used as an assistant.

10 cylinder 12 combustion chamber
20: piston 32: exhaust port
34: intake port 36: exhaust valve
38: moving port 41: crankcase
42: connecting rod 44: crankshaft

Claims (8)

piston;
A cylinder having a combustion chamber located above the piston;
An intake port connected to the cylinder to allow outside air to flow and an exhaust port connected to the cylinder to discharge combustion gas inside the combustion chamber;
A crankshaft installed at a lower portion of the cylinder and connected to the piston by a connecting rod and connected to the intake port;
An injector for injecting fuel into a high temperature region of the combustion chamber to induce self-ignition when the crankshaft rotation angle is 270 deg. ATDC; And
Installed on the exhaust port to open and close the exhaust port, and after self ignition has occurred, the exhaust port is closed at an opening angle of -25% to limit the open area of the exhaust port to 2 cm < 2 > A premixed compression self-igniting two-stroke gasoline engine comprising an exhaust valve partially blocking. The method of claim 1,
The injector is a pre-mixed compression self-ignition two-stroke gasoline engine, characterized in that the ejection port is inclined 25 to 40 degrees relative to the center axis of the cylinder toward the moving port connecting the interior of the crankcase and the combustion chamber. . delete delete delete delete delete delete

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