JP2007327370A - Opposed piston type two cycle engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact opposed piston type two cycle engine of high fuel efficiency by increasing thermal efficiency. <P>SOLUTION: In an opposed piston type two cycle engine 22 provided with an opposing first and second cylinder 23, 24 connected at tip parts and a scavenging side piston 25 and an exhaust side piston 26 reciprocating with synchronizing each other in the first and the second cylinder 23, 24, a scavenging hole 27 is provided at a bottom dead center position of the first cylinder 23 and an exhaust port 28 is provided at a bottom dead center position of the second cylinder 24, a scavenging valve 29 is provided at a canter side position of the bottom dead center of the first cylinder 23 and an exhaust valve 31 is provided at a center side position of the bottom dead center of the second cylinder 24, and expansion ratio of combustion gas is made large in relation to compression ratio of air is made large. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a two-cycle engine having two opposing cylinders connected to each other and an opposed piston driven synchronously by a crankshaft inside the cylinder.

In a general two-cycle engine, the thermal efficiency is high at a high speed load, but the thermal efficiency is reduced at a low speed load. This is due to the cooling loss of the piston head surface and the cylinder head. The reason for this is that the heat loss does not decrease even if the engine output decreases because the cooling heat transfer area does not change even when the load is low.
On the other hand, a horizontally opposed piston engine in which a piston is disposed oppositely in one piston solves the above problems because the area of the cylinder head is small. For example, Patent Document 1 discloses such a type of piston. An engine has been proposed.

Japanese National Patent Publication No. 9-505373

However, when the technology of the piston engine described in Patent Document 1 is applied to a two-cycle diesel engine, the process of compressing the intake air, then injecting the fuel to explode, and exhausting is a normal two-cycle diesel engine. As a result, the compression ratio and the expansion ratio become substantially the same in the end, and there is a problem that the output efficiency is lowered.
Furthermore, since the cylinder in which the two pistons are arranged to face each other is linear, a clearance is secured when both pistons are at the top dead center, and a portion for attaching the combustion injection valve and possibly a spark plug is provided. Must be configured. For this reason, there is a problem that heat loss is generated from the portion, and the thermal efficiency at the time of low-speed rotation is lowered.

Therefore, the present inventor previously proposed an opposed piston type two-cycle engine in Japanese Patent Application No. 2004-346147. An outline of the present invention is shown in FIG. 6, and a scavenging side piston 12 and an exhaust side piston 13 that are synchronously driven by being arranged opposite to each other are provided on the first and second cylinders 10 and 11 connected in a bent state, A scavenging hole 14 is provided on the bottom dead center side of the scavenging side piston 12 of the first cylinder 10, and an exhaust hole 15 is provided on the bottom dead center side of the exhaust side piston 13 of the second cylinder 11. After the side piston 12 and the exhaust side piston 13 were pushed down, air was introduced from the scavenging hole 14 and the combustion exhaust gas was deaerated from the exhaust hole 15. In addition, the scavenging side piston 12 and the exhaust side piston 13 are provided with crank arms 16 and 17, and the crankshafts 18 and 19 are driven to rotate. Reference numeral 20 denotes a fuel injection valve (or spark plug).

However, since this opposed piston type two-cycle engine is a two-cycle engine, if the exhaust gas remains in the air introduced from the scavenging holes or if fuel is mixed in the introduced air, a part of the fuel is present. In addition to the problem of leakage with exhaust gas, there is a problem that the compression efficiency and the expansion coefficient are constant and the efficiency as an engine is poor due to the structure.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide an opposed-piston two-cycle engine that is compact and has high thermal efficiency and high fuel efficiency.

The opposed-piston type two-cycle engine according to the present invention that meets the above-mentioned object is a scavenging side that reciprocates while synchronizing with each other in the first and second cylinders connected to each other at the front and the first and second cylinders. In the opposed piston type two-cycle engine provided with the piston and the exhaust side piston,
A scavenging hole is provided at the bottom dead center of the first cylinder, and an exhaust hole is provided at the bottom dead center of the second cylinder.
A scavenging valve is provided at a center side position from the bottom dead center of the first cylinder, and an exhaust valve is provided at a center side position from the bottom dead center of the second cylinder to increase the expansion ratio of the combustion gas with respect to the compression ratio of air. is doing.

In the opposed piston type two-cycle engine according to the present invention, the exhaust valve opens when the exhaust side piston is applied to the exhaust hole or immediately before the exhaust side piston, and the scavenging valve is when the scavenging side piston is applied to the scavenging hole. Alternatively, it is preferable that the exhaust valve and the scavenging valve are opened immediately thereafter, and are closed after the scavenging hole and the exhaust hole are closed.
In the opposed piston type two-cycle engine according to the present invention, it is preferable that the bending angle of the center line of the first and second cylinders is in the range of 10 to 45 degrees.
In the opposed piston type two-cycle engine according to the present invention, the tops of the scavenging side piston and the exhaust side piston are orthogonal to a plane including the center lines of the first and second cylinders, and the scavenging side piston and the An inner inclined surface and an outer inclined surface intersecting with the top of the exhaust side piston are formed, and the inner inclined surfaces formed on the scavenging side piston and the exhaust side piston are parallel to each other, and the scavenging side When the piston and the exhaust side piston are at top dead center, the inner inclined surfaces may be in contact with or in close contact with each other.

In the opposed piston type two-cycle engine according to the present invention, notches are formed at the tops of the scavenging side piston and the exhaust side piston, respectively, so that the scavenging side piston and the exhaust side piston are at top dead center. In some cases, a combustion chamber with a minimum space may be formed. Further, it is more preferable that a fuel injection valve is provided in an oblique direction with respect to the combustion chamber.

In the opposed piston type two-cycle engine of the present invention, a scavenging hole is provided at the bottom dead center position of the first cylinder, and an exhaust hole is provided at the bottom dead center position of the second cylinder. A scavenging valve is provided in the center side position from the bottom dead center of the cylinder, and an exhaust valve is provided in the center side position from the bottom dead center of the second cylinder to increase the expansion ratio of the combustion gas to the compression ratio of the air. Since the exposed portion of the cylinder head is small and the thermal efficiency is improved, an engine with higher combustion efficiency can be provided.

In the opposed piston type two-cycle engine of the present invention, the center lines of the first and second cylinders are tilted within a range of 10 to 45 degrees with respect to the straight line, and the first side of the scavenging side piston and the exhaust side piston are Forming an inner inclined surface and an outer inclined surface perpendicular to a plane including the center line of the second cylinder and intersecting the tops of the scavenging side piston and the exhaust side piston, respectively. When the inner inclined surfaces formed are parallel and the scavenging side piston and the exhaust side piston are at top dead center, the respective inner inclined surfaces are in contact or in close contact with each other. The combustion chamber can be efficiently formed in the space formed at the top of the scavenging side piston and the exhaust side piston, and if necessary, the space for installing the fuel injection pump and spark plug can be Head (i.e., first, second central connecting portion of the cylinder) can be secured.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIGS. 1A and 1B are partially omitted cross-sectional views of an opposed piston type two-cycle engine according to an embodiment of the present invention, and FIGS. 2A and 2B are one embodiment of the present invention. FIG. 3 is a perspective view of the scavenging side piston and the exhaust side piston, FIG. 4 is an explanatory view showing the relationship between each operation and the crank angle, and FIG. It is explanatory drawing which shows the attachment state of an injection valve.

As shown in FIGS. 1 to 3, an opposed piston type two-cycle engine 22 according to an embodiment of the present invention includes opposed first and second cylinders 23 and 24 connected at the front portion, and the first and second cylinders 23 and 24. The scavenging side piston 25 and the exhaust side piston 26 reciprocally move in synchronization within the second cylinders 23 and 24, respectively. The first and second cylinders 23 and 24 have the same inner diameter and the same length, and the distal end side is bent with respect to a straight line in the range of 10 to 45 degrees (more preferably 25 to 40 degrees) via the connecting portion 41 (that is, bending). Angled). A scavenging hole 27 is provided at the bottom dead center position of the first cylinder 23, and an exhaust hole 28 is provided at the bottom dead center position of the second cylinder 23.

An outlet 30 of the scavenging valve 29 is formed on the side wall of the first cylinder 23 at a position on the center side from the bottom dead center of the first cylinder 23, that is, a position adjacent to the center side of the scavenging hole 27. An inlet 32 of the exhaust valve 31 is formed in the second cylinder 24 at a position on the center side from the bottom dead center of the second cylinder 24, that is, a position adjacent to the exhaust hole 28 in the center direction. Although the crank arm is omitted in FIGS. 1 and 2, the basic configuration is the same as in FIG.
In addition, at the tops of the scavenging side piston 25 and the exhaust side piston 26, inner inclined surfaces 34, 35 and an outer inclined surface orthogonal to a plane including the center line (axial center line) of the first and second cylinders 23, 24 are provided. 36 and 37 are formed, respectively. The inner inclined surface 34 formed on the scavenging side piston 25 and the inner inclined surface 35 formed on the exhaust side piston 26 are parallel, and the scavenging side piston 25 and the exhaust side piston 26 are at top dead center. In this case, the inner inclined surfaces 34 and 35 are in contact with each other or in close contact with each other with a gap of 1 mm. The inner inclined surfaces 34 and 35 and the outer inclined surfaces 36 and 37 intersect at the tops of the scavenging side piston 25 and the exhaust side piston 26.

On the other hand, the outer inclined surfaces 36 and 37 form an angle of 90 to 120 degrees, for example. Further, as shown in FIG. 3, the tops of the scavenging side piston 25 and the exhaust side piston 26, that is, the inner inclined surface 34 and the outer inclined surface 36 of the scavenging side piston 25, and the inner inclined surface 35 and the outer inclined surface of the exhaust side piston 26. Notches 38 and 39 made of depressions are formed on the surface 37, respectively, and the notches 38 and 39 form the main part of the combustion chamber (ignition chamber, explosion chamber) 40. That is, when the scavenging side piston 25 and the exhaust side piston 26 are at the top dead center position, the space of the notches 38 and 39 and the outer inclined surfaces 36 and 37 continuous therewith, and the first and second cylinders 23 and 24. A space (initial space) formed by the inner wall of the connecting portion 41 is the maximum compressed space Vp of air containing air or fuel gas.

The outer portion (that is, the bent end portion) of the connecting portion 41 of the first and second cylinders 23 and 24 is thick and has a recess 42 formed therein. In this embodiment, the fuel injection valve 43 is provided. In the case of a gasoline engine, an ignition plug is provided instead of or together with the fuel injection valve 43. The fuel injection valve 43 injects fuel into the combustion chamber 40, but it is preferable to direct the fuel injection pump toward the inner tangential direction of the combustion chamber 40 for efficient filling.
Reference numerals 44a and 45a denote piston rings, 46a and 47a denote water jackets, and the scavenging valve 29 and the exhaust valve 31 are opened and closed at an appropriate time in synchronization with the crankshaft.

Next, the operation and action when the opposed piston type two-cycle engine 22 according to one embodiment of the present invention is used as a diesel engine will be described with reference to FIGS. 1, 2, and 4.
As shown in FIG. 1A, when fuel is blown into the combustion chamber 40 from the fuel injection valve 43 at the position where the scavenging side piston 25 and the exhaust side piston 26 are at the top dead center or just before that position, the fuel explodes. Combustion occurs, and the scavenging side piston 25 and the exhaust side piston 26 move toward the bottom dead center. In the opposed piston type two-cycle engine 22, the surface area of the cylinder block is smaller than that of an engine that does not connect the cylinders. Therefore, heat dissipation is reduced and the efficiency of the engine is improved.

As shown in FIG. 1B, when the scavenging side piston 25 and the exhaust side piston 26 approach the bottom dead center, the scavenging valve 29 and the exhaust valve 31 are closed, so that the compression force of the combustion gas remains as it is. 25 and the exhaust side piston 26 and can be recovered as power.
Then, as shown in FIG. 2 (A), when the scavenging side piston 25 and the exhaust side piston 26 further move in the direction of the bottom dead center and reach the crankshaft angle P (in this embodiment, the position is 135 degrees) An exhaust hole 28 formed in the second cylinder 24 is opened, and combustion exhaust gas is discharged. At this time, the exhaust valve 31 is also opened, and the combustion exhaust gas is released to the outside in a shorter time. As a result, the pressure inside the first and second cylinders 23 and 24 is lowered so that the combustion exhaust gas does not flow into the scavenging side when the scavenging holes 27 and the scavenging valve 29 are opened.
Thereafter, the scavenging side piston 25 and the exhaust side piston 26 further move toward the bottom dead center, the scavenging hole 27 is opened (position 141 degrees in this embodiment), and then the scavenging valve 29 is opened (position 147 degrees). ). As a result, the combustion exhaust gas in the first and second cylinders 23 and 24 is expelled and fresh air is introduced.

As shown in FIG. 2B, the scavenging side piston 25 and the exhaust side piston 26 move in the direction of the top dead center after passing through the bottom dead center, but first, the scavenging hole 27 is closed (at a position of 219 degrees). ) Next, the exhaust hole 28 is closed (at 225 degrees position).
When the scavenging side piston 25 and the exhaust side piston 26 move further to the top dead center side, the exhaust valve 31 is first closed (position 241 degrees), and then the scavenging valve 29 is closed (position 247 degrees). As a result, even after the exhaust valve 31 is closed, the scavenging valve 29 is opened and compressed air from the compressor is sent into the first and second cylinders 23 and 24.

In this embodiment, the scavenging valve 29 and the exhaust valve 31 are made of a rotating body, interlocked with the crankshaft, and delayed by a crank angle (that is, an exhaust lead angle, for example, 6 degrees) from the rotation of the crankshaft. ing.
By the action of the exhaust valve 31 and the scavenging valve 29 described above, in the opposed piston type two-cycle engine 22 of this embodiment, for example, an Atkinson cycle having a compression ratio of 17 and an expansion ratio of 21 is realized. At the same time, a filling efficiency as high as 70% is obtained. The filling efficiency is defined as follows.
Filling efficiency = (weight of gas remaining in cylinder and compressed) / (atmospheric weight of stroke volume)

The period from the opening of the scavenging hole 27 and the scavenging valve 29 to the closing is called the scavenging angle. If the scavenging angle is small, the scavenging must be performed in a short period of time, the pressure loss increases, and the filling efficiency decreases. Unsuitable for rotation. In this opposed piston type two-cycle engine 22, the scavenging angle can be set to 100 to 120 degrees (crank angle). As a two-stroke diesel engine for automobiles, sufficient scavenging time is obtained, and it is applied to high-speed rotation. is doing.

A mechanism for continuously changing the opening timing of the exhaust valve 31 is provided. With this mechanism, the above-described exhaust lead angle can be provided with a continuously variable function within a range of 6 to 21 degrees. The exhaust lead angle needs to be larger for higher speed rotation and higher load. Therefore, by increasing the opening timing of the exhaust valve 31 to 120 degrees (crank angle, indicated by Q in FIG. 4) during high-speed rotation, the exhaust lead angle can be increased to a crank angle of 21 degrees. In this opposed piston type two-cycle engine 22, it is understood that the thermal efficiency of the new energy-saving engine is 20% or more higher than that of the 4-stroke diesel engine. The reason is as follows.

1) There is no exhaust stroke and intake stroke, and there is no mechanical loss. The mechanical loss in this stroke in the 4-stroke system is due to the movement of the piston / crank mechanism and the gas flow loss in the cylinder, and increases particularly in the high-speed rotation range.
2) By adopting the refraction type opposed piston system, the surface area / volume ratio (S / V ratio) of the combustion chamber can be reduced, and a convex lens type combustion chamber having a large volume at the center can be obtained. By adopting a combustion chamber central combustion system that makes the most of the characteristics of the shape of the combustion chamber, the cooling loss near the top dead center position (ATDC -5 degrees to 30 degrees) can be halved.
3) An Atkinson cycle having a compression ratio of 17 and an expansion ratio of 21 can be realized, and the thermal efficiency is improved by about 5 to 6% as compared with the 4-stroke system.
4) The filling efficiency is 70%, which is high as two strokes, and is suitable for high-speed rotation than the four-stroke method, so that the output ratio per stroke volume can be more than double that of the four-stroke method.
5) There is no valve that consumes a large amount of power, and the corresponding mechanical loss can be eliminated. When the scavenging valve 29 and the exhaust valve 31 that are timing control valves are rotated at a constant rotational speed, only the rotational frictional force works. Gas pressure is applied to a section with a crank angle of 20 to 30 degrees per cycle. Only at this time, the gas pressure load is applied to the bearings of the scavenging valve 29 and the exhaust valve 31, but the value is small, for example, 300 N or less, and the rotational frictional resistance generated therefrom is slight.

Next, an opposed piston type two-cycle engine according to another embodiment of the present invention provided with a fuel injection valve as shown in FIG. 5 will be described.
In the opposed piston type two-cycle engine according to the present invention, the advantage that the combustion chamber 40 can be freely designed can be maximized because there is no valve like the 4-stroke engine in or around the combustion chamber 40. In this embodiment, the shape of the combustion chamber 40 of the opposed piston type two-cycle engine is a convex lens shape having a large volume at the center unlike the four-stroke type toroidal shape, and a combustion method suitable for the shape is adopted. It is possible to use stirring mixing by swirl (vortex) as in the conventional case.

Here, as an example of conceptual design, an example in which four fuel injection valves 45 to 48 are provided is shown in FIG. First, fuel is widely injected toward the center of the combustion chamber 40 by the fuel injection valve 45 on the center side. Thereafter, fuel is injected toward the peripheral portion of the combustion chamber centrifugal side by the peripheral fuel injection valves 46 to 48. Initially, the fuel injected by the fuel injection valve 45 self-ignites near the center of the combustion chamber 40 and combustion starts. Although this is the first half of the combustion stroke, the vicinity of the wall surface of the combustion chamber 40 is in an unburned state, and the heat load on the wall surface of the combustion chamber 40 is small. On the other hand, the injection timings of the respective fuel injection valves 45 to 48 are set so that the peripheral portion on the centrifugal side of the combustion chamber 40 is in an ignition state after the middle of the combustion stroke. In the first half of the combustion stroke, the fuel gas around the centrifugal chamber 40 is squished by the combustion expansion at the center of the combustion chamber 40 (the top surfaces of the scavenging side piston 25 and the exhaust side piston 26, that is, the inner inclined surfaces 34, 35). The inner inclined surfaces 36, 37 and the inner surfaces of the notches 38, 39).

Combustion of the fuel trapped in the squish area is delayed by the action of the boundary layer on the piston head squish surface and burned in the later stage of the combustion stroke. In this way, the heat load on the piston head squish surface can be reduced.
A heat insulating layer can be provided in the vicinity of the wall of the combustion chamber 40 by increasing the ratio of the amount of fuel injected into the center of the combustion chamber 40 during operation at a medium load. In this way, the cooling loss can be reduced particularly during low and medium load operation. Since the engine for automobiles is operated almost in a low and medium load region, the fuel consumption reduction effect is substantially high.
From the above, by adopting the combustion chamber central combustion system, a temperature difference in which the vicinity of the side wall of the cylinder (referring to the first and second cylinders 23 and 24) is low and the center is high can be provided in the centrifugal direction in the cylinder. . The amount of cylinder lubricant consumption is affected by the temperature atmosphere on the surface of the cylinder where the lubricant is applied. This temperature is lower than that of the 4-stroke method, and the consumption of lubricating oil can be suppressed to the same level or lower as that of the 4-stroke method.

Another advantage of the combustion chamber center combustion method is that the startability is good. Like the 4-stroke system, it is not directly affected by the cold combustion chamber wall. At the time of starting, only the fuel injection valve on the center side can be operated to suppress the unburned amount. Because the combustion chamber has high heat insulation, it can handle high loads in a short time. In the current 4-stroke system, the compression ratio is increased to 20 or more to ensure startability. However, high compression ratios increase the weight of the engine to withstand high pressures.

In this opposed piston type two-cycle engine, the compression ratio is set to 17, for example. This value is low for a direct fuel injection system and contributes to the weight reduction of the engine. Even if the compression ratio is lowered, since the Atkinson cycle having an expansion ratio of 21 is adopted, the thermal efficiency is improved.
In the case of the 4-stroke method, a pushing force is applied by the gas pressure in the combustion stroke at the top dead center position of the piston, but there is no gas pressure in the exhaust stroke and the intake stroke, and an inertial force that stretches and extends the piston acts. In consideration of this elongation, it is necessary to increase the gap in the squish area.
The space in the squish area is a space that cannot be directly used for the combustion reaction, and the concentration of fuel injected into the combustion chamber is increased by that amount, resulting in an increase in PM (Particulate Matter) and NOx generation. Since this opposed piston type two-cycle engine is a two-stroke system, the piston is always subjected to a pressing force due to gas pressure. Considering this, the space of the squish area at the position of the top dead center can be greatly reduced as compared with the 4-stroke method.

Assuming that the opposed piston type two-cycle engine according to this embodiment is about 1000 cc, the overall power performance is very similar to that of a 1300 cc gasoline engine. Compared to gasoline engines, this new energy-saving engine has higher thermal efficiency, especially at low loads. The mileage in 10.15 mode is increased up to 2 times.
The above is a description of a small diesel engine for passenger cars, but the application range of this opposed piston type two-cycle engine is wider.
Due to recent fuel situations, the use of petroleum alternative fuels for internal combustion engines has been expanded. This is the case with natural gas, DME (dimethyl ether), and alcohol-based fuels. And the combustion technology applied to these fuels is also developed. The new energy-saving engine has the advantage that there is no valve around the combustion chamber and the degree of freedom in combustion design is great. Because of this advantage, the new energy-saving engine can handle many types of fuel.

This opposed piston type two-cycle engine can also be applied to an exhaust turbo supercharging system. As described above, since the exhaust valve closes earlier than the scavenging valve, it can be supercharged smoothly to the scavenging air pressure level. In addition, since the Atkinson cycle is adopted, it is compatible with ultra-high supercharging of 1 Mpa or more, and the compatibility with the gas turbine is particularly good. Since the cooling loss and the mechanical loss can be reduced to about 2/3 of the 4-stroke method, a high overall thermal efficiency can be obtained. Since it can be combined with a gas turbine with a 1/3 exhaust capacity of the 4-stroke system, the installation space is compact.
The combined heat engine of the gas turbine combined cycle and the new energy-saving engine has the possibility of thermal efficiency in the 60% range.

In the opposed piston type two-cycle engine 22 according to this embodiment, if the engine speed increases, the combustion exhaust gas in the first and second cylinders 23 and 24 is not easily discharged to the outside. It is preferable to speed up. In this embodiment, the scavenging valve 29 and the exhaust valve 31 are connected to the crankshaft to open and close, but this is constituted by a high-speed operation type electromagnetic valve, taking into consideration the engine speed and fuel condition. Thus, the scavenging valve 29 and the exhaust valve 31 can be operated at an optimum angular position. The scavenging hole 27 and the exhaust hole 28 are physically determined by the relative positional relationship between the piston and the cylinder. If the scavenging hole 27 and the exhaust hole 28 are independently driven by an electrical signal, the scavenging valve 29 and the exhaust valve 31 are operated at an arbitrary time. be able to.

In the above-described embodiment, the case where the scavenging side piston 25 and the exhaust side piston 26 have substantially the same crank angle has been described, but the crank angle of the exhaust side piston 26 is 2 to 2 than the crank angle of the scavenging side piston 25. Preferably, it has a phase angle α advanced by 8 degrees (more specifically 6 degrees). This is partially introduced in the opposed piston type engine, but by making the opening of the exhaust hole 28 earlier than the opening of the scavenging hole 27, the blowback to the scavenging hole 27 can be prevented. 1 and 2, even if the scavenging holes 27 and the exhaust holes 28 are arranged symmetrically, a phase difference is provided in the opening angle between the exhaust holes 28 and the scavenging holes 27 (that is, the exhaust holes are opened first). As a result, the opening of the exhaust hole 28 can be accelerated. Further, the exhaust valve 31 can also be closed 6 degrees (2 to 8 degrees) earlier than the scavenging valve 29, for example. The phase angle α has an optimum value for maximizing the filling efficiency. If the phase angle α is too large, the filling efficiency decreases. Therefore, in the opposed piston type two-cycle engine 22 according to this embodiment, the angle is about 6 degrees.

(A), (B) is a partially omitted sectional view of an opposed piston type two-cycle engine according to an embodiment of the present invention. (A), (B) is a partially omitted sectional view of an opposed piston type two-cycle engine according to an embodiment of the present invention. It is a perspective view of a scavenging side piston and an exhaust side piston. It is explanatory drawing of the relationship between a crank angle (CA) and the operating state of an engine. It is explanatory drawing of the opposing piston type | mold 2 cycle engine which concerns on other embodiment of this invention which shows the attachment state of a fuel injection valve. It is explanatory drawing of the opposed piston type | mold 2 cycle engine which this inventor proposed previously.

Explanation of symbols

10: first cylinder, 11: second cylinder, 12: scavenging side piston, 13: exhaust side piston, 14: scavenging hole, 15: exhaust hole, 16, 17: crank arm, 18, 19: crankshaft, 20: Fuel injection valve, 22: Opposite piston type two-cycle engine, 23: First cylinder, 24: Second cylinder, 25: Scavenging side piston, 26: Exhaust side piston, 27: Scavenging hole, 28: Exhaust hole 29: Scavenging valve, 30: outlet, 31: exhaust valve, 32: inlet, 34, 35: inner inclined surface, 36, 37: outer inclined surface, 38, 39: notch, 40: combustion chamber, 41: connection Part, 42: depression, 43, 45-48: fuel injection valve, 44a, 45a: piston ring, 46a, 47a: water jacket

Claims (5)

In the opposed piston type two-cycle engine including the first and second cylinders connected at the front and facing each other, and the scavenging side piston and the exhaust side piston that reciprocate in the first and second cylinders in synchronization with each other,
A scavenging hole is provided at the bottom dead center of the first cylinder, and an exhaust hole is provided at the bottom dead center of the second cylinder.
A scavenging valve is provided at a center side position from the bottom dead center of the first cylinder, and an exhaust valve is provided at a center side position from the bottom dead center of the second cylinder to increase the expansion ratio of the combustion gas with respect to the compression ratio of air. An opposed-piston type two-cycle engine characterized by 2. The opposed piston type two-cycle engine according to claim 1, wherein the exhaust valve opens at or immediately before the exhaust-side piston enters the exhaust hole, and the scavenging valve has the scavenging-side piston applied to the scavenging hole. An opposed piston type two-cycle engine, which opens at or immediately after, and closes the exhaust valve and the scavenging valve after the scavenging hole and the exhaust hole are closed, respectively. 3. The opposed piston type two-cycle engine according to claim 1, wherein a bending angle of a center line of the first and second cylinders is in a range of 10 to 45 degrees. 4. Piston type 2 cycle engine. 4. The opposed piston type two-cycle engine according to claim 3, wherein the scavenging side piston and the exhaust side piston have apexes perpendicular to a plane including the center lines of the first and second cylinders, and the scavenging side piston and An inner inclined surface and an outer inclined surface intersecting the tops of the exhaust side pistons are formed, respectively, and the inner inclined surfaces respectively formed on the scavenging side piston and the exhaust side piston are parallel to each other so that the scavenging When the side piston and the exhaust side piston are at top dead center, the inner inclined surfaces are in contact with or in close contact with each other. The opposed piston type two-cycle engine according to any one of claims 1 to 4, wherein notches are formed at the tops of the scavenging side piston and the exhaust side piston, respectively, and the scavenging side piston and the exhaust side are formed. An opposed-piston type two-cycle engine characterized by forming a combustion chamber with a minimum space when the side piston is at top dead center.

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