JPH04128513A - Cylinder injecting type 2 cycle internal combustion engine - Google Patents

Abstract

PURPOSE:To promote vaporizing of fuel while accelerating combustion speed to obtain stable combustion by opening an inlet valve after opening an exhaust valve while closing the exhaust valve and the inlet valve nearly at the same time. CONSTITUTION:When an inlet valve 6 and an exhaust valve 7 are opened, air flows into a combustion chamber 4 from the inlet valve 6. Since an opening of the inlet valve 6 in the exhaust valve 7 side is covered with a mask wall 8a at this time, air flows into the combustion chamber 4 from the opening of the inlet valve 6 in the opposite side to the mask wall 8a. Air W flows in the combustion chamber 4 in a loop shape to exhaust burnt gas in the combustion chamber 4 from the exhaust valve 7 and generates a circulating flow X. Furthermore, the exhaust valve 7 and the inlet valve 6 are closed nearly at the same time to prevent the circulating flow X from being blown back into an inlet port 12 to be attenuated. Fuel is injected toward a recessed inner wall surface of a recessed groove 15 from a fuel injection valve 14 to be delivered into a recessed part 16 so as to form an ignitable air-fuel mixture around an ignition plug 10.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a direct injection two-stroke internal combustion engine.

[Conventional technology]

The opening of the air supply valve located on the exhaust valve side is covered by a mask wall during the full opening period of the air supply valve, and the air sent out from the mechanical supercharger is transferred to the air supply valve located on the opposite side of the exhaust valve. A two-stroke internal combustion engine is known in which loop scavenging is performed by flowing air into a combustion chamber through a sekiguchi (see Japanese Patent Laid-Open No. 2-49923'8). In this two-stroke internal combustion engine, as shown in FIG. 10, the exhaust valve opens before the intake valve, and the exhaust valve closes before the intake valve.

[Problem to be solved by the invention]

That is, in this two-stroke internal combustion engine, in order to supply air into the cylinder after exhaust blowdown, the exhaust valve is opened and then the intake valve is opened. In order to supply the air sent out from the mechanical supercharger into the cylinder even after the valve is closed, the air supply valve is closed after the exhaust valve is closed. However, in reality, when the exhaust valve is closed and the outflow of burned gas is stopped, not only does the inflow of air into the cylinder stop, but if the intake valve is subsequently opened, the piston rises. It was discovered that the movement caused the air or burnt gas in the cylinder to be blown back into the air supply boat through the air supply valve. By the way, when air is caused to flow in a loop within the combustion chamber, a swirling flow is generated within the combustion chamber. This swirling flow continues while being gradually increased in force while air is flowing into the cylinder through the air supply valve, and begins to attenuate when the air inflow from the air supply valve stops. However, if the air supply valve remains open even after the exhaust valve closes, some of the swirling air or burnt gas will blow back into the air supply boat as described above, causing the swirling flow to rapidly attenuate. Put it away. As a result, there is a problem that not only is it not possible to sufficiently promote the vaporization of the fuel supplied into the cylinder, but also that it is not possible to increase the combustion rate due to the swirling flow and obtain stable combustion.

[Means for Solving the Problems] In order to solve the above problems, according to the present invention, an air supply valve and an exhaust valve are provided, and the opening of the air supply valve located on the exhaust valve side is covered by a mask wall. In a direct injection type two-stroke internal combustion engine, after the exhaust valve is opened, the intake valve is opened, and the exhaust valve and the intake valve are closed almost simultaneously, and the piston top surface is recessed into a groove. When the exhaust valve and the air supply valve are closed almost simultaneously, the swirling air is ignited by the ignition plug. Since the swirling flow is not blown back, the swirling flow continues without being suddenly attenuated, and therefore the fuel injected into the groove is well vaporized by the swirling flow.

[Example] Referring to FIGS. 1 and 3, l is a cylinder block, 2 is a piston that reciprocates within the cylinder block 1,
Reference numeral 3 indicates a cylinder head fixed on the cylinder block 1, and reference numeral 4 indicates a combustion chamber formed between the inner wall surface 3a of the cylinder head 3 and the top surface of the piston 2. A recessed groove 5 is formed on the cylinder head inner wall surface 3a, and a pair of air supply valves 6 are arranged on the cylinder head inner wall surface portion 3b forming the bottom wall surface of the recessed groove 5. On the other hand, the cylinder head inner wall surface portion 3C excluding the groove 5 is inclined and substantially flat, and a pair of exhaust valves 7 are arranged on this cylinder head inner wall surface portion 3C. The cylinder head inner wall surface portion 3b and the cylinder head inner wall surface portion 3C are connected to each other via the peripheral wall 8 of the groove 5. This concave groove peripheral wall 8 is arranged very close to the peripheral edge of the air supply valve 6 and extends in an arc shape along the peripheral edge of the air supply valve 6. It is constituted by a guide wall 8b and a pair of fresh air guide walls 8c located between the peripheral wall of the cylinder head inner wall surface 3a and the air supply valve 6. Each mask wall 8a extends toward the combustion chamber 4 below the intake valve 6 at the maximum lift position, and therefore the opening between the peripheral edge of the intake valve 6 and the valve seat 9 located on the exhaust valve 7 side is The air supply valve 6 is closed by the mask wall 8a throughout its opening period. Moreover, each fresh air guide wall 8b.

8c are located in substantially the same plane, and furthermore, these fresh air guide walls 8b, 8c extend substantially parallel to the line connecting the centers of both intake valves 6.9 The spark plug 10 is located within the cylinder head. It is arranged on the cylinder head inner wall surface portion 3c so as to be located at the center of the wall surface 3a. On the other hand, the exhaust valve 7 is not provided with a mask wall that covers the opening between the exhaust valve 7 and the valve seat 11, so that when the exhaust valve 7 opens, the exhaust valve 7
The entire opening formed between the valve seat 11 and the valve seat 11 opens into the combustion chamber 4.

The intake valve 6 and the exhaust valve 7 are driven by an intake valve drive cam 24 and an exhaust valve drive cam by a compression spring 21 and a compression spring 22, respectively, which urge the intake valve 6 and the exhaust valve 7 in the closing direction. It is pressed to 25.

The intake valve drive cam 24 and the exhaust valve drive cam 25 are configured to rotate in synchronization with the engine crankshaft at a rotational speed equal to the rotational speed of the engine crankshaft.

As the intake valve drive cam 24 and the exhaust valve drive cam 25 rotate, the intake valve 6 and the exhaust valve 7 are opened and closed.

Inside the cylinder head 3, an air supply boat 1 is provided for an air supply valve 6.
2 is formed, and an exhaust boat 13 is formed for the exhaust valve 7. On the other hand, a fuel injection valve 14 is arranged at the peripheral edge of the cylinder head inner wall surface 3a between both intake valves 6, and fuel is injected from this fuel injection valve 14 into the combustion chamber 4.

As shown in FIGS. 1 and 2, a groove 15 is formed at the top of the piston 20 and extends from below the spark plug 10 to below the tip of the fuel injection valve 14.

In the embodiment shown in FIGS. 1 and 2, this groove 15
-K on a vertical plane containing the spark plug 10 and the fuel injection valve 14
It has an almost spherical shape that is symmetrical to the surface. Also, piston 20
A recess 16 having a spherical shape with a smaller curvature than the groove 15 is formed at the center of the top surface. This recess 16 is also formed upwardly in the vertical plane, and this recess 16 opens at the upper part of the concave inner wall surface of the groove 15. As shown in FIG. 1, when the piston 2 reaches the top dead center, the ignition plug 10 moves into the recess 16.
invade inside.

On the other hand, the top surface portion 2a of the piston 2 on the opposite side of the groove 15 with respect to the recess 16 is formed as an inclined or substantially flat surface, and as shown in FIG. A squish area 17 is formed between the wall portion 3c and the bisto top portion 28.

FIG. 6 shows an enlarged view of the exhaust valve drive cam 25, the relationship between the 'xzx' crank angle and the lift 1 of the exhaust valve 7, and FIG. 4 shows the opening/closing timing of the intake valve 6 and the exhaust valve 7.

As shown in FIG. 4, in the embodiment shown in FIGS. 1 to 3, the exhaust valve 7 opens before the intake valve 6, and the exhaust valve 7 and the intake valve 6 close almost simultaneously.

Also, as shown by the solid line in Fig. 6, the exhaust valve drive cam 2
The cam shape of the opening side lift section and the cam shape of the closing side lift section of No. 5 are defined by a straight line M passing through the transition point T from the opening side lift section to the closing side lift section -1 and the rotation center 0 of the exhaust valve drive cam 250. -MA
The shape is almost symmetrical.

Therefore, as shown by the solid line in FIG.
As the valve rotates, the valve lift curve E at the opening side lift portion of the exhaust valve 7. It decreases almost symmetrically. On the other hand, similarly to the exhaust valve driving cam 25, the intake valve driving cam 24 has a cam shape that is almost symmetrical to the opening side lift section and the cam shape of the closing side lift section L7. The amount of lift at the closing side lift portion of the air supply valve 6 decreases as the intake valve drive cam 24 rotates, almost symmetrically with the valve lift 1-curve applied to the opening side lift portion of the air intake valve 6. .

Further, in FIG. 4, L indicates the fuel injection timing during high engine load operation, and Ib+ and hhz indicate the fuel injection timing during high engine load operation. Therefore, it can be seen from FIG. 4 that during high-load engine operation, fuel injection is performed in two steps. Furthermore, as shown in Figure 4, the first fuel injection of 1kl during high engine load operation
is performed when the exhaust valve 7 and the intake valve 6 are closed, or before and after the exhaust valve 7 and the intake valve 6 are closed, and the second fuel injection 16□ is performed at 5 points before the top dead center TDC. 0 degrees 8
It can be seen that this is done at about 0 degrees. It can also be seen that the fuel injection timing during low engine load operation is later than the second fuel injection timing Ik2 during high engine load operation.

Next, two injection methods for low load operation and high load operation will be explained with reference to FIG.

As shown in FIG. 5(A), when the intake valve 6 and the exhaust valve 7 are opened, air flows into the combustion chamber 4 through the intake valve 6. At this time, since the opening of the air supply valve 6 of the exhaust valve 7@ is covered by the mask wall 8a, air flows into the fuel chamber 4 from the opening of the air supply valve 6 on the side opposite to the mask wall 8a. This air is filtered along the inner wall surface of the cylinder bore below the intake valve 6 as shown by the arrow W, then travels along the top surface of the piston 20, and moves along the inner wall surface of the cylinder bore below the exhaust valve 7 at an angle of ±4°. Thus, the air flows in a loop inside the combustion chamber 4. The air W flowing in this loop causes the combustion chamber 4 to
Burnt gas inside the combustion chamber 4 is discharged through the exhaust valve 7, and the air W flowing in a loop generates a swirling flow X that swirls in a vertical plane within the combustion chamber 4. Next, the piston 2 passes the bottom dead center BDC and begins to rise, and after a while, the exhaust valve 7 and the air supply valve 6 close almost simultaneously. When the exhaust valve 7 and the air supply valve 6 close almost simultaneously in this way, the swirling air as shown by the arrow X is not blown back into the air supply bow 2, and therefore the swirling flow X is rapidly attenuated. No more getting caught.

As a result, the swirling flow X generated within the combustion chamber 4 continues to swirl strongly. On the other hand, when the intake valve 6 and the exhaust valve 7 are closed, fuel injection from the fuel injection valve 14 is performed.

FIGS. 5(B) and 5(C) show the engine at low load operation, and FIGS. 5(D), (E), and (F) show the engine at high load operation.

As shown in FIG. 5(B), fuel is injected from the fuel injection valve 14 toward the concave inner wall surface of the groove 15. As shown in FIG. In the embodiment shown in FIGS. 1 to 3, the spray of the injected fuel has, for example, a conical shape as shown in FIG. 5(B), and the injection axis Z of the injected fuel is shown in FIG. 2. Located within - in the vertical plane.

During low-load engine operation, the injected fuel along the injection axis Z forms an oblique groove 1 without an acute angle θ, as shown in FIG. 5(B).
It collides with the concave inner wall surface of No.5. When the injected fuel collides obliquely with the concave inner wall surface of the concave groove 15 in this way, the collided fuel moves along the concave inner wall surface of the concave groove 15 due to the inertia force as shown by Fl in FIG. 5(C). While being vaporized, the spark plug advances below the spark plug 10, and then is sent into the recess 16. When the engine is operating at low load, the injection t is small, but at this time most of the injected fuel is carried below the ignition plug 10, so that an ignitable air-fuel mixture is formed around the ignition plug 100.

Further, as shown in FIG. 5(A), the swirling flow X generated in the combustion chamber 4 is attenuated little by little as the piston 2 rises, and the swirling radius gradually becomes smaller, causing the piston 2 to approach the top dead center. and groove 1 as shown in FIG. 5(B).
6 becomes a swirling flow X along the concave inner wall surface. Even though it is said to attenuate little by little, a strong swirling flow
A downward force of 0 is applied. Furthermore, as the piston 2 approaches the top dead center, a squish flow ejects from the squish area 17 as shown by arrow S in FIG. 5(C), and this squish flow S also flows along the concave inner wall surface of the groove 15 move on. Therefore, the squish flow S also gives the injected fuel a force directed downward to the spark plug 10. Further, the fuel flowing downward along the concave inner wall surface of the concave groove 15 is vaporized by the strong swirling flow It will gather your attention. In this way, even when the engine is operating at low load with a small injection amount, good ignition and subsequent good combustion can be obtained.

On the other hand, during high-load engine operation, the first fuel injection Thl is performed from the fuel injection valve 14 before and after the exhaust valve 7 closes, as described above. In this manner, the first fuel injection 11 is performed before and after the exhaust valve 7 closes, so that the injected fuel cannot blow through into the exhaust boat 13 via the exhaust valve 7.

Further, when the first fuel injection Nkl is performed, the position of the piston 2 is low as shown in FIG. 5(D),
Therefore, the injected fuel is made to collide over a wide range of the top surface of the piston 2. At this time, the piston 2 is cooled by the injected fuel, and since the injected fuel receives heat from the piston 2, vaporization of the injected fuel is promoted.

At this time, a strong swirling flow X as shown in FIG. 5(A) is generated in the combustion chamber 4, so the injected fuel and air are mixed well, and since the injection timing is early, the injection The fuel is given sufficient time to vaporize. Therefore, a uniform air-fuel mixture is formed in the combustion chamber 4 before ignition by the spark plug 10. Note that since the fuel injection is performed in two steps, the air-fuel mixture formed in the combustion chamber 4 by the first injection of 1kl of fuel is a fairly lean mixture; A homogeneous mixture is formed. This air-fuel mixture is heated by the high-temperature burnt gas remaining in the combustion chamber 4, but since the air-fuel mixture is lean, the fuel density is low, and therefore this air-fuel mixture does not self-ignite.

That is, there is no self-ignition and no combustion noise, and no knocking occurs.

Next, as shown in FIG. 5(E), the second fuel injection I2 is started when the piston 2 is at a lower position than when the engine is operating at low load. At this time, Fig. 5 (E
), the injected fuel along the injection axis Z is in the groove 1.
It collides almost perpendicularly onto the concave inner wall surface of No. 5. When the injected fuel collides almost perpendicularly onto the concave inner wall surface of the concave groove 15, the collided fuel will move around the collision point of the injected fuel along the injection axis Z, as shown by F2 in FIG. 5(F). It spreads in all directions on the concave inner wall surface of the groove 15.

Therefore, in this case, some of the injected fuel that collided with the ignition plug 1
0 and then fed into the recess 16. In this way, when the engine is operated under high load with a large amount of injection, a part of the injected fuel is sent around the spark plug 10.
The air-fuel mixture formed around the ignition plug 100 does not become too rich, and thus an air-fuel mixture that can be well ignited is formed around the ignition plug 100. In addition, during high-load engine operation, the injected fuel is dispersed over a wide area on the high-temperature concave inner wall surface of the groove 15, so vaporization of the injected fuel is promoted. Since the amount of fuel injected into the cylinder is small, the injected fuel is sufficiently vaporized. Furthermore, even during high-load engine operation, a strong swirling flow X as shown in Fig. 5(B) and a skinsh flow S as shown in Fig. 5(C) are generated.
．． Therefore, the injected fuel 11□ and air are sufficiently mixed by the swirling flow X and the skin flow S, so that good combustion without smoke generation can be obtained.

Next, another embodiment will be explained. In the present invention, as described above, by closing the exhaust valve 7 and the intake valve 6 almost simultaneously, the air W flowing in a loop inside the combustion chamber 4 (see FIG. 5(A)) is removed from the air at the end of the scavenging stroke. In this way, the air swirling as shown by the arrow X (see FIG. 5(A)) is prevented from blowing back into the air supply boat 12. However, as in the above-described embodiment shown by the solid line in FIGS. 6 and 7, the valve lift curve at the closing side lift portion of the exhaust valve 7! Ec is the valve lift curve E at the opening side lift section. In the case of a symmetrical shape, not only the burnt gas is discharged into the exhaust boat 13 through the exhaust valve 7 by the air W flowing in a loop, but also the air (fresh air) is discharged at the end of the scavenging stroke. It becomes easy to flow out into the exhaust boat 13. In order to prevent air from blowing into the exhaust valve 13 in this way, in another embodiment, the exhaust valve 7
Then, the intake valve 6 is closed almost simultaneously, and the valve lift amount E at the closing side lift portion of the exhaust valve 7 is changed to the valve lift amount E at the opening side lift portion as shown by the two-dot chain line in FIGS. The lift amount is smaller than the lift amount E0. Note that the valve lift amount EcZ in the closing side lift section is set to be small within a range where the pressure within the combustion chamber 4 does not become higher than the pressure within the intake air opening 2.

In this way, while preventing the swirling air from blowing back into the air supply boat 12 as shown by the arrow can be reduced. Furthermore, in this second embodiment, the flow of burned gas and air from the inside of the combustion chamber 4 to the inside of the exhaust boat 13 is more greatly restricted by the exhaust valve 7 at the end of the scavenging stroke than in the first example. Therefore, the pressure inside the combustion chamber 4 is increased compared to the case of the first embodiment, and thus the engine output can be improved. Furthermore, by reducing the valve lift ilEcm at the closing side lift portion of the exhaust valve 7 in this way, the exhaust valve 7 can be seated gently on the valve seat 11.
It is possible to reduce the noise generated when the vehicle is seated.

By the way, in this second embodiment, as in the case of the first embodiment, the air swirling in the combustion chamber 4 as shown by the arrow X enters the air supply boat 12 via the air supply valve 6. Since there is no blowback, the swirling flow X is not suddenly attenuated. However, since the lift amount of the exhaust valve 7 in the latter half of the scavenging stroke is smaller than in the case of the first embodiment, the effect of discharging the burned gas into the exhaust boat 13 at the end of the scavenging stroke is reduced, and as a result, The inflow effect of air from the intake valve 6 is reduced, and the strength of the swirling flow X is slightly weaker than in the first embodiment before and after the exhaust valve 7 is closed. Therefore, during high load operation of the engine, it is necessary to mix a large amount of fuel and air well by using this somewhat weakened swirl flow X.Therefore, during high load operation, the fuel injection valve 14 as shown in FIG. Instead of carrying out the fuel injections 1kl and Toz in two parts, the fuel injections I6 are carried out in one batch before and after the exhaust valve 7 is closed, as shown in FIG.

As a result, since the fuel is injected all at once while the swirling flow X is as strong as possible, and the fuel injection timing is early, a large amount of injected fuel and air are well mixed by the swirling flow X, and are injected into the combustion chamber 4. A homogeneous air-fuel mixture is formed, thus achieving good combustion.

In addition, the valve lift curve IE of the exhaust valve 7 shown in FIG.
Whether to select Cl or E C2, or whether to inject fuel once (1wa) or twice (11 and 18.) during high engine load operation depends on the structure of the engine and the high load. The optimum one can be selected depending on the air-fuel ratio during operation.

In the above description of the embodiments, embodiments in which the present invention is applied to a two-stroke internal combustion engine equipped with two intake valves 6 and two exhaust valves 7 have been described.

However, the number of intake valves and the number of exhaust valves are not limited to this. For example, as shown in FIG. 9, the present invention may be applied to a two-stroke internal combustion engine equipped with two intake valves and three exhaust valves. The same can be applied.

Referring to the ninth episode, a pair of air supply valves 6 are arranged on the cylinder inner wall surface portion 3b that forms the bottom wall surface of the groove 5 formed on the cylinder inner wall surface 3a. On the other hand, the cylinder head inner wall surface portion 3C excluding the groove 5 is inclined and substantially flat, and a pair of first exhaust valves 7a and one second exhaust valve 7b are arranged on this cylinder head inner wall surface portion 3C. be done.

The cylinder hem 1'' inner wall surface portion 3b and the cylinder head inner wall surface portion 3C are connected to each other via a circumferential wall 8 of a groove 5, and this groove circumferential wall 8 is connected to a pair of supply ports as shown in FIG. It extends from one peripheral edge of the cylinder inner wall surface 3a to the other peripheral edge between the air valve 6, the first exhaust valve 7a, and the second exhaust valve m7b. 6 and a first exhaust valve 7a arranged adjacent to the air supply valve 6, a pair of mask walls 8 are arranged extremely close to the peripheral edge of the air supply valve 6 and extend in an arc shape along the peripheral edge of the air supply valve 60.
a, a fresh air guide wall 8b located between the air supply valves 6, and a pair of fresh air guide walls 8C located between the peripheral wall of the cylinder head inner wall surface 3a and the air supply valves 6. Each mask wall 8a extends toward the combustion chamber 4 below the intake valve 6 at the maximum lift position, and therefore the first
The opening between the peripheral edge of the air supply valve 6 and the valve seat 9 located at the exhaust valve 7a@ is closed by the mask wall 8a throughout the opening period of the air supply valve 6. Further, the ignition plug 10 is arranged on the cylinder head inner wall surface portion 3C so as to be located at the center of the cylinder head inner wall surface 3a.

On the other hand, the first exhaust valve 7a and the second exhaust valve 7b are not provided with a mask wall that covers the opening between the exhaust valves 7a, 7b and the valve seat 11, so the exhaust valve 7a is not provided with a mask wall that covers the opening between the exhaust valves 7a, 7b and the valve seat 11.

When the exhaust valve 7b opens, the entire opening formed between the exhaust valves 7a and 7b and the valve seat 11 opens into the combustion chamber 4.

In the embodiment shown in FIG. 9, the air supply valves 6 are arranged adjacent to each other.
and the first exhaust #7δ and the mask wall 8 formed between them.
One set of supply/exhaust valves consisting of a is provided, and in addition to these two sets of supply/exhaust valves, one second exhaust valve 7b is provided. The second exhaust valve 7b is a pair of first exhaust valves 7a.
The second exhaust valve 7
b is arranged at a position farther from the air supply valve 6 than the first exhaust valve 7a.

In the cylinder head 3, an air supply boat 12 is formed for each air intake valve 6, and an exhaust boat 3 is formed for each exhaust valve 7a, 7b, respectively. On the other hand, a fuel injection valve 1 is provided at the peripheral edge of the cylinder head inner wall surface 3a between both intake valves 6.
4 is arranged, and fuel is supplied from this fuel injection valve 14 to the combustion chamber 4.
It is sprayed inward.

The other configurations are the same as in the first embodiment.

In the embodiment shown in FIG. 9, the opening area of the exhaust valve is increased compared to the embodiment shown in FIG. It increases and becomes second. In this way, when the first H1 view 7a and the second exhaust valve 7b open, the pressure inside the combustion chamber 4 decreases more quickly, and as a result, fresh air easily flows into the combustion chamber 4. It is possible to increase the amount of fresh air sent to the

In addition, in the embodiment shown in the 9th part, as in the case of the above-mentioned embodiment, the first exhaust valve 7a and the second exhaust valve 7b are It is possible to set the valve lift curve at the closing side lift part to an appropriate valve lift curve within Ec+ or EczO shown in Fig. 7, and also to make the valve lift curve twice as shown in Fig. 4 during high load operation. The fuel injections 1kl and I2 may be performed separately, or the fuel injections I and I may be performed all at once as shown in FIG.

[Effects of the invention] The swirling flow generated in the combustion chamber can be sustained without being significantly attenuated, so the vaporization of the fuel injected into the groove can be promoted, thus achieving good ignition. and,
Subsequent good combustion can be obtained.

[Brief explanation of drawings]

Figure 1 is a side sectional view of a two-stroke internal combustion engine, Figure 2 is a plan view of the piston in Figure 1, Figure 3 is a bottom view of the cylinder head in Figure 1, and Figure 4 is an opening of the supply and exhaust valves. A line diagram showing timing and fuel injection timing, Figure 5 is a diagram to explain the state inside the combustion chamber during engine operation, Figure 6 is an enlarged view of the exhaust valve drive cam, and Figure 7 is a diagram showing the crank angle and exhaust valve. vA times showing the relationship between lift amounts, FIG. 8 is a diagram showing the opening timing of the intake and exhaust valves and fuel injection timing in another embodiment, FIG. 9 is a bottom view of the cylinder head in yet another embodiment, FIG. 10 is a diagram showing the opening timing of a conventional supply and exhaust valve. 2...Piston, 4...Combustion chamber, 6...
- Air supply valve, 7... Exhaust valve, 8a... Mask wall, 10... Ignition plug, 14... Fuel injection valve, 15... Recessed groove, 16... Recessed part. 1st 2... Piston 4... Combustion chamber 6... Air intake valve 7... Exhaust valve 80... Mask wall diagram 10... Spark plug 14... Fuel injection valve 15... Concave groove 16... Concavity Diagram (C) Diagram (D) Diagram (E) TDC Diagram TDC Diagram 10

Claims (1)

[Claims] In a direct injection two-stroke internal combustion engine that is equipped with an intake valve and an exhaust valve, and in which the opening of the intake valve located on the exhaust valve side is covered by a mask wall, the intake valve is opened after the exhaust valve is opened. A cylinder that closes an exhaust valve and an intake valve almost simultaneously, injects fuel into a groove formed on the top surface of the piston, and ignites the fuel injected into the groove with an ignition plug. Internal injection 2-stroke internal combustion engine.