JPH0893599A - Fuel injection device for two-cycle engine - Google Patents

Abstract

PURPOSE: To improve engine output and fuel consumption by controlling the blow-by of fuel to the minimum and quickening the diffusion of the fuel in a cylinder. CONSTITUTION: The fuel injection device of a two-cycle engine has the first and the second injectors 31,32, and in a low load region, fuel is jetted from the first injector 31, and a fuel-air mixture is stratified-charge burnt, and in medium and high load regions, the fuel is jetted from the first and the second injector 31,32, and the mixture is premixedly burnt. The second injector 32 is attached to a cylinder wall above an auxiliary scavenging port 12 opposite to an exhaust port. In medium and high load regions, since the spray of the fuel jetted from the second injector 32 is moved by an opposite scavenging flow q4 sent from the auxiliary scavenging port 12 pointing upward in a cylinder 2a to turn in the cylinder 2a, the fuel is hard to blow by through toward the exhaust port 13, and therefore sufficiently diffused in the cylinder 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection system for a two-cycle engine which causes stratified charge combustion in a low load range and premixed combustion in a medium / high load range.

[0002]

2. Description of the Related Art Generally, a two-cycle engine is prone to misfire in a low speed / low load range, so stratified combustion is performed in that range and premixed combustion is performed in a high load range. It is desirable from the standpoint of improving fuel efficiency and improving fuel efficiency.

Therefore, as shown in FIG. 18, the first injector 131 and the second injector 132 are attached to the cylinder head 108, and fuel is supplied from the first injector 131 to the spark plug 109 in the cylinder 102a in the low and medium load regions. Directly injects to perform stratified combustion of the air-fuel mixture, and in the high load range, the first injector 131 and the second injector 131
A fuel injection device has been proposed in which fuel is injected into the cylinder 102a from both of the injectors 132 to perform premixed combustion of an air-fuel mixture (see Japanese Patent Laid-Open No. 4-103855).

[0004]

However, the second injector 132 is attached to the cylinder head 108 together with the first injector 131, and the fuel is injected downward from the second injector 132 (in the direction of the piston 103). Fuel spray is scavenging port 112
It is easy to blow through the exhaust port 113 with the scavenging air from
There is a concern that engine output will decrease and fuel consumption will deteriorate.

Therefore, in the conventional fuel injection device, the fuel is injected from the second injector 132 after the exhaust port 113 is completely closed by the piston 103. However, the fuel injection time becomes extremely short especially in a high rotation speed range, so that there arises a problem that a necessary and sufficient amount of fuel cannot be injected.

The present invention has been made in view of the above problems, and an object of the present invention is to promote diffusion of fuel in a cylinder to improve engine output and fuel consumption while minimizing blow-through of fuel. It is an object of the present invention to provide a fuel injection device for a two-cycle engine capable of improving the fuel consumption.

[0007]

In order to achieve the above object, the invention according to claim 1 is provided with first and second injectors, and in a low load region, fuel is injected from the first injector to produce a mixture. In a fuel injection device for a two-cycle engine, which performs stratified combustion and injects fuel from the first and second injectors in a medium / high load range to premix and burn the air-fuel mixture, a scavenging gas in which the second injector faces an exhaust port It is characterized in that it is attached to the cylinder wall above the port.

The invention according to claim 2 is characterized in that, in the invention according to claim 1, the second injector is attached to a position lower than an upper end of the exhaust port.

Further, the invention according to claim 3 is characterized in that, in the invention according to claim 1 or 2, the second injector is provided with atomizing means for diffusing the fuel spray in the longitudinal direction. To do.

[0010]

According to the first aspect of the invention, since the second injector is mounted on the cylinder wall above the scavenging port facing the exhaust port, the spray of the fuel ejected from the second injector in the high load region is the cylinder. It swirls in the cylinder by riding on the opposite scavenging airflow that points upwards. Therefore, the fuel does not easily blow through the exhaust port, and the fuel is sufficiently diffused in the cylinder, so that the engine output is improved and the fuel consumption and the exhaust gas characteristics are improved.

According to the second aspect of the invention, since the second injector is attached to a position lower than the upper end of the exhaust port, the second injector is opened after the exhaust port is opened and high temperature and high pressure exhaust gas is discharged. The injector opens into the cylinder. Therefore, the injection port of the second injector has a high temperature
It is not exposed to high-pressure exhaust gas, and carbon contained in the exhaust gas does not adhere to the injection port and accumulate.

Further, according to the invention of claim 3, the second
Since the atomization means diffuses the fuel spray injected from the injector in the vertical direction for a long time, the fuel blow-through can be suppressed more efficiently.

[0013]

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

FIG. 1 is a block diagram showing the structure of a two-cycle engine equipped with a fuel injection device according to the present invention, FIG. 2 is a vertical cross-sectional view showing the internal structure of the same two-cycle engine, and FIG. 2 is a sectional view taken along the line BB in FIG.
FIG. 5 is an explanatory view of the operation of the air amount control means.

First, the basic structure of the two-cycle engine 1 will be described with reference to FIG.

The two-cycle engine 1 according to this embodiment is
Stratified combustion is performed in a low load region, and premixed combustion is performed in a medium / high load region. A piston 3 is vertically slidably fitted in a cylinder 2a formed in the cylinder block 2. There is. The piston 3 is connected via a connecting rod 5 to a crankshaft 4 arranged below the piston 3 in a direction perpendicular to the plane of FIG. A crank chamber 7 is formed inside the upper crankcase 2b integrally formed with the cylinder block 2 and the lower crankcase 6 connected to the lower surface of the upper crankcase 2b. 4 is rotatably supported and stored.

A cylinder head 8 is attached to the upper surface of the cylinder block 2, and the cylinder head 8 is attached.
A combustion recess 8a is formed in the combustion chamber 8a, and the combustion chamber 8 is defined by the combustion recess 8a and the piston 3. Further, a spark plug 9 is screwed onto the top of the cylinder head 8,
The electrode portion 9a of the ignition plug 9 faces the combustion chamber S.

As shown in FIG. 3, the cylinder head 8 is formed with two main scavenging ports 10 and 11, one auxiliary scavenging port 12 and one exhaust port 13. The above two main scavenging ports 1
0 and 11 are formed at positions facing each other, and the auxiliary scavenging port 12 is formed at a position facing the exhaust port 13. The upper scavenging port 12 of the auxiliary scavenging port 12 opens toward the upper side of the cylinder 2a. Therefore, the scavenging air from the auxiliary scavenging port 12 is hardly blown to the exhaust port 13. An air inlet 14 that opens to the crank chamber 7 is formed in the lower portion of the cylinder block 2, and the air inlet 14 has a reed valve 15 that allows only air to flow toward the crank chamber 7. Is provided.

An intake pipe 16 is connected to the air inlet 14, and an air amount adjusting device 17 is connected to the intake pipe 16.
The intake manifold 18 is connected via.

The air amount adjusting device 17 uses the operation amount (engine load) of an accelerator pedal (not shown) in the accelerator device 19 shown in FIG. 1 and the engine speed as parameters to crank the air from the air inlet 14 through the reed valve 15. The amount of air sucked into the chamber 7 is controlled, and this is the intake ports 20a, 21a formed at the top and bottom.
Main valve 20 and sub valve 21 for opening and closing
have. The main valve 20 and the sub valve 21
Is always biased toward the closing side by a biasing means (not shown).

As shown in FIG. 4, the drive shafts 22 and 23 of the main valve 20 and the sub-valve 21 are provided with potentiometers 24 and 25 for detecting the openings of the valves 20 and 21, respectively. A motor 26 is connected to the drive shaft 23 of each sub-valve 21.

As shown in FIG. 5, the main valve 20
A first swing piece 27 is connected to one end of the drive shaft 22 of the above, and a second swing piece 28 is connected to one end of the drive shaft 23 of the sub valve 21. A groove 27a (see FIG. 4) and a locking hole 27b (see FIG. 5) are provided on the outer peripheral portion of the first swing piece 27.
The throttle wire 29 having one end connected to the accelerator device 19 is wound around the groove 27a, and the other end of the throttle wire 29 is the locking hole 27b of the first swinging piece 27. Is locked to.

Further, as shown in FIG.
The connecting rod 30 is disposed between the first swinging piece 27 and the second swinging piece 28.
The other end 30b is slidably engaged with an arcuate guide groove 28a formed in the second swing piece 28.

On the other hand, as shown in FIG. 2, the side wall portion of the cylinder head 8 is mainly subjected to stratified charge combustion in a low load operation range, and fuel is supplementarily supplied also in other operation ranges. First injector 31 for
Is mounted on the side wall of the cylinder block 2 just above the auxiliary device port 12 and below the upper end of the exhaust port 13 in the middle and high load regions. The 2nd injector 32 for performing is carried out.

Details of the structure of the first injector 31 will now be described with reference to FIGS. 6 to 8. 6 is an enlarged cross-sectional view of the C portion of FIG. 2, FIG. 7 is a view in the direction of arrow D of FIG. 6,
FIG. 8 is a sectional view taken along the line EE of FIG.

As shown in FIGS. 6 to 8, the first injector 31 has one injection port 33 having a relatively large diameter and three injection ports 34, 35, 36 having a relatively small diameter, and the injection port 35.
Is opened on the axis center line, and injection ports 34 and 36 are opened on both sides of the injection port 35.

As shown in FIG. 6, the injection port 33 is formed upward in a direction forming an angle θ ₁ with respect to the axis in the vertical section, and the injection ports 34, 36 on both sides are
As shown in FIG. 8, they are formed in a direction that forms an angle θ ₂ with the axis in the cross section.

Next, details of the configuration of the second injector 32 will be described with reference to FIG. Note that FIG. 9 is an enlarged detailed view of the F portion of FIG.

The second injector 32 has two injection ports 38a and 38b which are opened at a predetermined angle θ _3, and the center line of the angle θ ₃ is directed to the installation position of the spark plug 9. . Therefore, the fuel injected from the two injection ports 38a, 38b collides with each other and atomizes, and as shown in FIG.

Next, the second injector 3 according to another embodiment.
Details of the configuration 2 will be described with reference to FIGS. 10 to 12. In addition, FIG. 10 is an enlarged detailed view of the tip portion of the second injector,
11 is a view in the direction of arrow G in FIG. 10, and FIG. 12 is a sectional view of the spray (a sectional view taken along the line NN of FIG. 10).

Nozzles 37 attached to the tip of the second injector 32 are formed with injection ports 39, 40 of different sizes, and fuel spray is injected in the vicinity of the openings of the injection ports 39 of large diameter. A straight wire 41, which constitutes atomization means for long diffusion in the vertical direction, is provided laterally through the axial centers of both injection ports 39, 40.

Thus, the closer the position of the wire 41 is to the small-diameter jet port 40 and the larger the diameter of the wire 41, the larger the vertical length y of the spray spread shown in FIG.

Further, the position of the wire 41 is set to the small-diameter injection port 4
By arranging it slightly below the center line of 0, the spray can be directed upward as a whole.

Incidentally, as the atomizing means provided in the second injector 32, it is also conceivable to provide a flange-shaped stopper 42a at the tip of the needle 42 as shown in FIG. Here, as the outer diameter of the stopper 42a is made larger than the diameter of the needle 42, the spray can be expanded. Further, by making the outer shape of the stopper 42a oval, the spray can be made vertically long, the center of the oval stopper 42a is slightly displaced from the center line of the needle 42, and the outside of the stopper 42a is By increasing the diameter toward the upper side, the spray can be directed upward as a whole.

Here, the overall construction of the fuel injection device according to the present invention will be described with reference to FIG. In addition, in FIG.
The same elements as those shown in FIGS. 2 to 5 are denoted by the same reference numerals, and description thereof will be omitted below.

In FIG. 1, reference numeral 45 denotes an intake port of the intake manifold 18, arrow a indicates the flow of air (fresh air) sucked in from the intake port 45, and arrow b exhausts the two-cycle engine 1. The respective exhaust gas flows are shown below.

By the way, the rotational power of the crankshaft 4 of the two-cycle engine 1 is transmitted to the external load 50 via the output shaft 46, the gears 47, 48 and the input shaft 49, but at the end of the crankshaft 4, A measurement gear 51 for detecting the engine speed and the crank angle is connected. A reference crank angle indicating tooth is formed on the measuring gear 51.

Further, in FIG. 1, reference numeral 52 is a fuel supply device for supplying a constant pressure fuel to the first injector 31 and the second injector 32, and 53 is for controlling the timing of ignition by the spark plug 9. The ignition timing control device 54 is a rotation speed sensor that also serves as a crank angle sensor, and the rotation speed sensor 54 is arranged near the measurement gear 51. In the measurement gear 51, the width of only the teeth facing the rotation speed sensor 54 is set to be small corresponding to the time when the piston 3 is at the bottom dead center (BDC). The reference crank angle signal is sent to an engine control unit (ECU) described later.
Unit) 55 and a crank angle signal indicating the amount of rotation of the crankshaft 4 from the reference crank angle position to the engine control device 55. In FIG. 1, reference numeral 56 is a memory.

The fuel injection device is provided with the engine control unit (ECU) 55. The engine control unit 55 detects the engine speed and the crank angle detected by the speed sensor 54. , The main valve 2 detected by the potentiometers 24, 25
0 and each opening degree of the sub valve 21 (especially, the main valve 20
Of the air, that is, the engine load (accelerator operation amount in the accelerator device 19), the air amount control means 17
(Motor 26 (opening degree of sub-valve 21)) and first and second
By controlling the injectors 31 and 32 (fuel injection timing and fuel injection amount) and the ignition timing control device 53 (ignition timing), stratified charge combustion is performed in the low load region where the engine load is small, and in the medium and high load regions. Is for premixed combustion.

Here, the operation of the two-cycle engine 1 will be outlined.

As shown in FIG. 2, when the piston 3 is located at the bottom dead center (BDC), the main scavenging ports 10, 1 are
1, the auxiliary scavenging port 12 and the exhaust port 13 are open, and at this time, the fresh air introduced into the crank chamber 7 in the previous cycle and compressed by the piston 3 is the main scavenging port 1
The exhaust gas that flows into the cylinder 2a through 0 and 11 and the auxiliary scavenging port 12 and pushes out the exhaust gas remaining in the cylinder 2a from the exhaust port 13 to the outside of the cylinder 2a is performed.

Next, when the piston 3 moves upward in the cylinder 2a from the bottom dead center, first, the main scavenging ports 10 and 11 are released.
And the auxiliary scavenging port 12 is closed by the piston 3,
After that, the exhaust port 13 is also closed by the piston 3 and the compression stroke in which the fresh air introduced into the cylinder 2a is compressed is shifted, but in the low load region where the engine load is small, the compression stroke after the scavenging stroke is performed. Fuel is locally injected from the first injector 31 toward the electrode portion 9a of the spark plug 9. That is, the first injector 31
Fuel is injected from the injection port 33 (see FIG. 6) toward the ignition plug 9 as shown in FIG. 14 to form an injection fuel flow q _1, and the fuel is injected from the three injection ports 34 to 36. Is injected toward an intermediate region between the spark plug 9 and the piston 3 of the combustion chamber S to form an injected fuel flow q ₂ . As a result, a rich air-fuel mixture is formed around the electrode portion 9a of the ignition plug 9, and this rich air-fuel mixture is ignited and ignited by the ignition plug 9, and stratified combustion is performed.

On the other hand, in the medium / high load range where the engine load is larger than the predetermined value, the first and second engine speeds have already been reached during the scavenging stroke.
Fuel injection is started from the injectors 31 and 32 into the cylinder 2a, and this fuel injection ends before the compression stroke.

Here, the behavior of the spray of fuel injected from the second injector 32 will be described with reference to FIGS. 14 to 16. 14 is a vertical sectional view of the cylinder portion of the two-cycle engine, FIG. 15 is a schematic plan sectional view of the cylinder portion, and FIG. 16 is a sectional view taken along line HH of FIG.

In the scavenging stroke, as described above, the fresh air introduced into the crank chamber 7 and compressed by the piston 3 in the previous cycle is the main scavenging ports 10 and 11 and the auxiliary scavenging port 1.
The exhaust gas flowing into the cylinder 2a via 2 and remaining in the cylinder 2a is pushed out of the exhaust port 13 to the outside of the cylinder 2a by the fresh air and is discharged. At this time, the fresh air flowing into the cylinder 2a from the main exhaust ports 10 and 11 becomes a scavenging air flow q ₃ toward the exhaust port 13 in a substantially horizontal plane at the same height as the exhaust port 13, as shown in FIG. The exhaust gas remaining in the cylinder 2a is quickly pushed out to the exhaust port 13.

On the other hand, the fresh air flowing into the cylinder 2a from the auxiliary scavenging port 12 facing the exhaust port 13 is as shown in FIG.
As shown in FIG. 4, an upward facing scavenging air flow q ₄ directed to the combustion chamber S is turned and swirls in the cylinder 2a. Therefore, the time until the fresh air is discharged to the exhaust port 13 is the main scavenging port 11, It becomes longer than that of fresh air flowing in from 12.

Thus, in this embodiment, as described above, the second
The fuel spray ejected from the injector 32 rides on the counter scavenging air flow q ₄ directed upward in the cylinder 2a and swirls in the cylinder 2a to travel a long distance. Therefore, the fuel is hard to blow through the exhaust port 13, It is sufficiently diffused in the cylinder 2a. Then, when the piston 3 reaches near the top dead center, the combustible air-fuel mixture in the combustion chamber S is ignited and burned by the fireworks of the spark plug 9, and so-called premixed combustion is performed. Fuel exhaust port 1
Since the blow-through to No. 3 is suppressed, the engine output per predetermined amount of fuel is improved, that is, the fuel consumption is improved and the exhaust gas characteristics are improved.

Particularly, in this embodiment, the second injector 3
Since the injection ports 38a and 38b are provided at 2 in FIG. 2 at an angle of θ ₃ , the spray of the fuel injected from the second injector 32 is long in the vertical direction as shown by the hatched area I in FIG. Since the vertical length y of the spray becomes larger than the width x (y> x), the blow-through of the fuel to the exhaust port 13 can be suppressed more efficiently. As described above, in the example shown in FIG. 10, the wire 41 is arranged slightly below the center line of the small-diameter injection port 40, and the injected fuel collides with the wire 41, as shown in FIG. In the example, by colliding the injected fuel with the elliptic flange-shaped stopper 42a that is deviated upward, the fuel spray can be diffused in the longitudinal direction for a long time as shown in FIG.

Further, in this embodiment, as described above, since the second injector 32 is attached to a position lower than the upper end of the exhaust port 13, the exhaust port 13 is opened and high temperature and high pressure exhaust gas is discharged. Then, the second injector 32 opens in the cylinder 2a. Therefore, the second
The injection ports 38a, 38b of the injector 32 are not exposed to high-temperature and high-pressure exhaust gas, and carbon contained in the exhaust gas does not adhere to the injection ports 38a, 38b and accumulate.

In the present embodiment, the second injector 32
Is attached substantially horizontally, but as shown by the chain line in FIG. 14, the second injector 32 may be attached obliquely so that its tip end opens toward the combustion chamber S.

On the other hand, as the piston 3 rises, a negative pressure is generated in the crank chamber 7, and this negative pressure introduces fresh air through the intake manifold 18, the intake amount control device 17, the intake pipe 16 and the reed valve 15. It is introduced into the crank chamber 7 through the mouth 14.

When the piston 3 descends past the top dead center by the explosive force due to the combustion of the air-fuel mixture in the combustion chamber S, the fresh air introduced into the crank chamber 7 is compressed by the piston 3 and compressed. The generated fresh air is used for scavenging and mixture formation in the next cycle. Then, when the piston 3 descends to near the bottom dead center, the exhaust port 13 is first opened, and the exhaust gas generated by the combustion of the air-fuel mixture is discharged from the exhaust port 13. After that, continue to main scavenging port 1
When 0, 11 and the auxiliary exhaust port 12 are opened, the crank chamber 7
The fresh air compressed inside flows into the cylinder 2a from the main scavenging ports 10 and 11 and the auxiliary scavenging port 12 to perform the scavenging action.

Thereafter, the same operation as described above is repeated, and 2
The cycle engine 1 is continuously operated.

Next, the combustion control method will be described with reference to FIGS. Note that FIG. 17 is a diagram showing changes in the opening area of the intake port 20a with respect to the opening α of the main valve 20 (engine load).

When the two-cycle engine 1 is in the stopped state, both the main valve 20 and the sub valve 21 are in the fully closed state, and in the idling state, the motor 26 is driven by the control signal from the engine control unit 55, and the sub valve is driven. 21 is opened by a predetermined angle in the direction of the arrow as shown by the chain line in FIG. Therefore, in the idling state of the engine 1 (opening α = 0 of the main valve 20), the opening area of the intake port has a value (opening area of the intake port 21a) indicated by point ID in FIG. 17, and is not shown. The air that has passed through the idle port and the sub-valve 21 passes through the reed valve 15 and flows from the air inlet 14 to the crank chamber 7.
Since it is introduced into the cylinder 2a, a large amount of air is introduced into the cylinder 2a and supplied to the scavenging air as compared with the conventional idling state, so that the scavenging efficiency during idling is enhanced.

In FIG. 17, the broken line J indicates the opening area of the intake port 20a of the main valve 20, and the chain line K indicates the total opening area of the intake ports 20a and 21a of both valves 20 and 21. Further, a broken line L represents a change in the opening area of the intake port 21a of the sub-valve 21 when the engine speed is maintained at 1500 rpm, and a solid line M
Shows changes in the opening area of the intake port 21a of the sub-valve 21 when the engine speed is kept at 4000 rpm.

Thus, the amount of depression of the accelerator pedal in the accelerator device 19 is small and the throttle wire 2
Since the turning angle between the first swinging piece 27 and the main valve 20 which are turned by 9 is small, the potentiometer 2
In a low load range (α <α ₀ ) in which the opening degree α of the main valve 20 detected by 4 is smaller than a set value α ₀ (this value α ₀ changes depending on the engine speed), the engine control device 55 Instead of driving and controlling the sub-valve 21 by the connecting rod 30, the motor 26 is controlled and driven to rotate the sub-valve 21 in the direction of the arrow as shown by the solid line in FIG. By controlling the ignition timing control device 53, stratified combustion of the air-fuel mixture is performed in the combustion chamber S.

Therefore, in the low load region where the stratified charge combustion is executed, when the accelerator pedal of the accelerator device 19 is gradually depressed, the main valve 20 gradually opens and
The engine control device 55 reads the operation (engine load) of the main valve 20 by the potentiometer 24 without being directly driven by the operation of the main valve 20, and feeds back the potentiometer 25 so as to set a predetermined opening based on this value. Motor 26 while hanging
Control. Then, the sub valve 21 is opened by the drive control of the motor 26, and the intake port 2 of the sub valve 21 is opened.
The opening area of 1a is the broken line L in FIG. 16 (when the engine speed is 1
500 rpm) or solid line M (engine speed is 4)
000 rpm). in this way,
In the low load region where stratified charge combustion is performed, fresh air is also supplied through the sub-valve 21, so that a large amount of fresh air is temporarily supplied to the scavenging air in the cylinder 2a, and scavenging efficiency and exhaust gas characteristics are improved. .

Then, the opening α of the main valve 20 is set to a value α ₀ (α ₀ = 1 when the engine speed is 1500 rpm).
At 5 ° and 4000 rpm, α ₀ = 25 °) is reached,
Since the engine control device 55 releases the drive control of the motor 26, the sub-valve 21 rapidly closes in the closing direction until the end of the guide groove 28a formed in the second swing piece 28 contacts the end 30b of the connecting rod 30. Turn to. As a result, as shown in FIG. 17, the intake port 21a of the sub-valve 21 is
When the opening α of the main valve 20 increases by depressing the accelerator pedal thereafter, the second swinging piece 28 is driven by the connecting rod 30 to rotate the first swinging piece 27. Interlock with the movement. As a result, the sub-valve 21 rotates integrally with the main valve 20 in the opening direction, and the intake ports 20a, 21 of both valves 20, 21 are rotated.
The sum of the opening areas of a increases along the dashed line K in FIG.
In addition, in FIG. 17, a hatched region indicates a stratified combustion region.

Thus, in the medium / high load range in which the opening degree α of the main valve 20 becomes equal to or larger than the set value α ₀ (α ≧ α ₀ ), the premix combustion is performed as described above. First, when the opening degree α of the main valve 20 is less than a certain set value α ₁ (> α ₀ ), that is, until the sub valve 21 is suddenly closed and then opened, as in the low load region, The fuel is injected only from the first injector 31, the ignition timing control device 53 retards the ignition timing sufficiently from the value in the low load region, and the mixture formed by the sufficiently diffused fuel is ignited. The air-fuel mixture is ignited and burned to perform premixed combustion.

When the opening α of the main valve 20 exceeds the set value α ₁ , fuel is supplied from both the first injector 31 and the second injector 32, and
The ignition timing is controlled by the ignition timing control device 41, the air-fuel mixture formed by the sufficiently diffused fuel is ignited, and the air-fuel mixture is ignited and burned to perform premixed combustion.

[0062]

As is apparent from the above description, according to the present invention, the first and second injectors are provided, and in the low load region, fuel is injected from the first injector to perform stratified combustion of the air-fuel mixture, In a fuel injection device for a two-cycle engine in which fuel is injected from the first and second injectors to premix and combust the air-fuel mixture in the medium / high load range, the second injector is provided above the scavenging port facing the exhaust port. Since it is attached to the cylinder wall, it is possible to obtain the effect that the blow-through of the fuel can be minimized, the diffusion of the fuel in the cylinder can be promoted, and the engine output and the fuel consumption can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a two-cycle engine including a fuel injection device according to the present invention.

FIG. 2 is a vertical cross-sectional view showing the internal structure of a two-cycle engine including a fuel injection device according to the present invention.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a sectional view taken along line BB in FIG.

FIG. 5 is a diagram illustrating the operation of the air amount control means.

FIG. 6 is an enlarged cross-sectional view of a C part of FIG.

7 is a view in the direction of arrow D in FIG.

8 is a cross-sectional view taken along the line EE of FIG.

FIG. 9 is an enlarged detailed view of an F portion of FIG.

FIG. 10 is an enlarged detailed view of a second injector tip portion according to another embodiment.

11 is a view in the direction of arrow G in FIG.

12 is a sectional view of the spray (a sectional view taken along the line NN of FIG. 10).

FIG. 13 is a cross-sectional view of a second injector tip portion showing a modified embodiment of atomization means.

FIG. 14 is a vertical cross-sectional view of a cylinder portion of a two-cycle engine including a fuel injection device according to the present invention.

FIG. 15 is a schematic plan sectional view of a cylinder portion of a two-cycle engine including a fuel injection device according to the present invention.

16 is a cross-sectional view taken along line HH of FIG.

FIG. 17 is a diagram showing changes in the opening area of the intake port with respect to the opening of the main valve (engine load).

FIG. 18 is a cross-sectional view of a main part of a two-cycle engine including a conventional fuel injection device.

[Explanation of symbols]

 1 2 cycle engine 10,11 Main scavenging port 12 Auxiliary scavenging port 13 Exhaust port 31 First injector 32 Second injector 38a, 38b Injection port (atomization means) 41 Wire (atomization means) 42a Stopper (atomization means)

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02M 69/00 310 P 69/04 Z

Claims (3)

[Claims] 1. A first injector and a second injector, wherein fuel is injected from the first injector in a low load range to stratify the air-fuel mixture, and fuel is injected from the first and second injectors in a medium / high load range. In a fuel injection device of a two-cycle engine that injects
The second injector is attached to the cylinder wall above the scavenging port facing the exhaust port.
Fuel injection device for cycle engine. 2. The fuel injection device for a two-cycle engine according to claim 1, wherein the second injector is attached below an upper end of the exhaust port. 3. The fuel injection device for a two-cycle engine according to claim 1, wherein the second injector includes atomizing means for diffusing the fuel spray in a longitudinal direction.