JPH09250429A - Fuel injecting/supplying type engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To supply a sufficiently large quantity of fuel to a combustion chamber of a fuel injecting/supplying type engine even at a high speed under a high load in the engine in which a fuel injection port capable of supplying injected fuel to the combustion chamber of the engine is formed on a cylinder. SOLUTION: A fresh air passage 22 is provided for communicating a crank chamber 3 with a combustion chamber 21 formed inside a cylinder hole 8. When a piston 11 is slid, outside air 19 is temporarily taken into the crank chamber 3, to be preliminarily compressed. The preliminarily compressed air 19 is supplied to the combustion chamber 21 via the fresh air passage 22. A fuel injection port 28 capable of supplying injection fuel 29 toward the combustion chamber 21 is formed on the cylinder 7. A communication path 32 for communicating the fuel injection port 28 with the inside of the crank chamber 3 after a head 12 of the piston 11 passes the fuel injection port 28 during a stroke up to a top dead center of the piston 11 is formed on a skirt 13 of the piston 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crank chamber precompression engine, and a fuel injection supply type engine in which a fuel injection port capable of supplying injection fuel to a combustion chamber of the engine is formed in a cylinder. Is.

[0002]

2. Description of the Related Art Conventionally, there is a fuel injection supply type engine constructed as follows in a two-cycle engine.

According to this, a cylinder is provided so as to protrude from the crankcase, and a piston is slidably fitted in a cylinder hole of the cylinder in the axial direction thereof. A fresh air passage that connects the crank chamber of the crankcase to the combustion chamber in the cylinder hole is formed in the cylinder, and by the sliding of the piston, the outside air is once sucked into the crank chamber and precompressed, The precompressed air is supplied to the combustion chamber through the fresh air passage. Further, a fuel injection port is formed in the cylinder so that the injected fuel can be supplied from the outside of the cylinder toward the combustion chamber of the cylinder hole.

When the engine is driven to perform the sweeping process, the exhausting process, and the compression process, the fuel injection valve
Injection fuel is directly supplied to the combustion chamber through the fuel injection port. Then, the air pre-compressed in the crank chamber and supplied to the combustion chamber and the fuel are compressed in the combustion chamber by the same piston.

Next, as described above, the mixture of compressed air and fuel is burned by the discharge of the spark plug, and this combustion forces the piston to slide toward bottom dead center. To be

Then, the crankshaft which is interlocked with the piston is rotated in one direction, and the crankshaft outputs the power of the engine to the outside.

[0007]

By the way, at the time of high speed and high load, it is required to shorten the time for one fuel injection and increase the injection amount, but it is not enough to satisfy this requirement. Neither a 2-cycle engine nor a 4-cycle engine is easy, so at high speed and high load,
There is a problem that the amount of fuel to be supplied to the combustion chamber tends to be insufficient.

Therefore, it is conceivable to increase the capacity of the fuel injection valve for supplying the fuel to the combustion chamber through the fuel injection port so that a large amount of fuel is injected in a short time in one fuel injection.

However, in a two-cycle engine, if this is done, then in a "blowing through phenomenon" in which part of the fuel supplied to the combustion chamber is discharged as it is through the exhaust passage, There is a risk that the dark portion will blow through, that is, a large amount of fuel will blow through, and fuel consumption may deteriorate.

Therefore, as described above, there is a possibility that a sufficiently large amount of fuel cannot be supplied to the combustion chamber by simply increasing the capacity of the fuel injection valve.

In a two-cycle engine and a four-cycle engine, when a large amount of fuel is injected into the combustion chamber, it may be difficult to vaporize the fuel in a short time to form a combustible mixture in the combustion chamber. Part of the injected fuel burns incompletely, and exhaust gas containing a large amount of HC, COx, etc. is discharged. Further, in this case, fuel economy is deteriorated due to partial incomplete combustion.

The present invention has been made in view of the above circumstances and is a crank chamber precompression type engine having a fuel injection port capable of supplying injection fuel to a combustion chamber of the engine. It is an object of the fuel injection supply type engine formed as described above to supply a sufficiently large amount of fuel to the combustion chamber of the engine without deteriorating fuel efficiency even at high speed and high load.

[0013]

A fuel injection type engine of the present invention for achieving the above object is as follows.

According to the first aspect of the present invention, the crankcase 2 is provided with a cylinder 7, and a piston 11 is slidably fitted in a cylinder hole 8 of the cylinder 7 in the axial direction thereof. 3 is provided with a fresh air passage 22 communicating with the combustion chamber 21 in the cylinder hole 8, and the piston 11 slides so that the air 19 outside thereof is once sucked into the crank chamber 3 and precompressed. The injected air 19 is supplied to the combustion chamber 21 through the fresh air passage 22, and a fuel injection port 28 that allows the injection fuel 29 to be supplied from the outside of the cylinder 7 toward the combustion chamber 21 is provided. When the piston 11 is formed in the cylinder 7, after the head portion 12 of the piston 11 passes through the fuel injection port 28 during the ascending stroke of the piston 11 to the top dead center, The injection port 28 is obtained by forming the communication passage 32 for communicating with the crank chamber 3 to the skirt portion 13 of the same piston 11.

According to the invention of claim 2, in addition to the invention of claim 1, the fuel injection port 28 is passed through the fresh air passage 22 to the combustion chamber 2
It is connected to 1.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment)

1 to 4 show a first embodiment.

Reference numeral 1 in the drawing is a crank chamber precompression type engine which is a two-cycle internal combustion engine, and this engine 1 is of a fuel injection supply type and is mounted on a motorcycle, an automobile or the like.

The engine 1 has a crankcase 2, and the inside of the crankcase 2 serves as a crank chamber 3, and a crankshaft 5 having an axis 4 extending substantially horizontally is internally provided in the crankcase 3. The shaft 5 is supported by the crankcase 2 so as to be rotatable around its axis 4.

A cylinder 7 is provided so as to project from the crankcase 2. One end of the cylinder 7 is located in the crank chamber 3
And a cylinder hole 8 which is communicated with and closed at the other end. A piston 11 is slidably fitted in the cylinder hole 8 in the axial direction (vertical direction) with the axis 9 of the cylinder hole 8 viewed vertically as shown in the drawing. The piston 11 includes a disk-shaped head portion 12 located on the axis 9 and a cylindrical skirt portion 13 that integrally extends from the head portion 12 toward the lower crankcase 2 side. The skirt portion 13 and the crankshaft 5 are connected to each other by a connecting rod 15 by a piston pin 14 supported by the skirt portion 13.

An intake passage 17 for communicating the outside of the crankcase 2 with the inside of the crank chamber 3 is formed in the crankcase 2. The reed valve 18 is provided in the intake passage 17.
The reed valve 18 is provided in the crankcase 2
The outside air 19 can flow only into the crank chamber 3 side.

The upper end of the cylinder hole 8 is a space closed by the piston 11, which serves as a combustion chamber 21. The cylinder 7 is provided with a fresh air passage (scavenging passage) 22 that communicates the crank chamber 3 with the combustion chamber 21. An ignition plug 23 whose discharge portion faces the combustion chamber 21 is attached to the upper portion of the cylinder 7.
An exhaust passage 25 that communicates the combustion chamber 21 with the outside of the cylinder 7 is formed, and an exhaust control valve 26 is provided at the upstream end of the exhaust passage 25.

A fuel injection port 28 for communicating the outside of the cylinder 7 with the combustion chamber 21 is provided, and the fuel injection port 28 is formed on the peripheral wall of the cylinder hole 8 in the combustion chamber 21. An electromagnetic switching type fuel injection valve 30 is provided which can inject fuel 29 through the fuel injection port 28 and supply the fuel 29 to the combustion chamber 21.

The spark plug 23 and the fuel injection valve 30 are automatically controlled by being connected to an electronic control device.

As shown in FIG. 1, when the piston 11 is located on the top dead center side, the fuel injection port 28 communicates with the cylinder hole 8 on the crank chamber 3 side of the head portion 12 of the piston 11. The communication passage 32, which is a through hole,
Piston ring 5 of the skirt portion 13 of the piston 11
It is formed closer to 1.

When the engine 1 is driven, the piston 11 slides in the cylinder hole 8 toward the top dead center (forward movement).
At this time, the forward movement causes the crank chamber 3 to have a negative pressure, and this negative pressure causes the air 19 outside the crankcase 2 to be sucked into the crank chamber 3 through the intake passage 17 and the reed valve 18. process).

Next, the piston 11 is moved to the top dead center (see FIG. 4).
In the middle, the crank angle θ = 0 °) is reached, and from there, it slides (returns) toward the bottom dead center, but the piston 11 is on the top dead center side (θ = 307.5 ° to 52 in FIG. 4). .5 °) (including the ascending stroke toward the top dead center of the piston 11 (during forward movement) and the descending stroke toward the bottom dead center (during backward movement)). (When located in the vicinity) and the piston 11
When the head portion 12 of the engine is located on the top dead center side of the fuel injection port 28, the fuel injection valve 30 sequentially passes through the fuel injection port 28, the communication passage 32, and the cylinder hole 8 to move the crank. The injected fuel 29 can be supplied to the chamber 3 (FIG. 1).

The supply of the injected fuel 29 by the fuel injection valve 30 when the piston 11 is on the top dead center side is as shown in FIG.
The injection fuel 29 is supplied by at least one of the solid line, the one-dot chain line, and the two-dot chain line, that is, the injected fuel 29 is supplied at at least a part of the crank angle on the top dead center side.

When the piston 11 returns from the top dead center, the air 19 sucked into the crank chamber 3 in the suction process is
And the fuel 29 supplied to the crank chamber 3 through the communication passage 32 or the like is pre-compressed. During this precompression, the fuel 29 injected into the crank chamber 3 is vaporized.

Further, when the piston 11 returns, the exhaust passage 25 is first opened (θ = 97 ° in FIG. 4), and then the fresh air passage 22 is opened (θ = 120 in FIG. 4).
°). Then, the pre-compressed air 19 and the fuel 29 are supplied to the combustion chamber 21 through the fresh air passage 22 in a mixture state.

Next, when the piston 11 reaches the bottom dead center (θ = 180 ° in FIG. 4) and moves forward from this bottom dead center toward the top dead center, the fresh air passage 22 is first closed. (Θ = 240 ° in FIG. 4), and then the exhaust passage 25 is closed (θ = 263 ° in FIG. 4). When the piston 11 further moves forward, it is pre-compressed in the crank chamber 3 and the combustion chamber 2
The air 19 and the fuel 29 that have been supplied to No. 1 are compressed by the piston 11 in the combustion chamber 21.

In the above case, when the piston 11 is on the bottom dead center side (θ = 66.5 ° to 293.5 ° in FIG. 4), the fuel injection valve 30 allows the fuel injection port 28 to pass through. The injected fuel 29 is directly supplied to the combustion chamber 21 (FIG. 2), and this fuel 29 is also compressed by the forward piston 11 (compression process).

Then, as described above, the air-fuel mixture compressed in the combustion chamber 21 and the fuel 29 is burned by the discharge of the spark plug 23 before the top dead center, and the piston causes the combustion. 11 is forcibly returned (combustion process).

At this time, in the same manner as described above, the air 19 and the fuel 29 precompressed in the crank chamber 3 are supplied to the combustion chamber 21 through the fresh air passage 22, and the air 1
9 and the fuel 29 scavenges the combustion chamber 21 (scavenging process), and at this time, the combustion gas generated by the combustion in the combustion chamber 21 is discharged to the outside of the cylinder 7 as the exhaust 34 (exhaust process).

Then, the suction process and the compression process described above are performed substantially at the same time, and then the scavenging process and the exhaust process are performed at substantially the same time through the combustion process, which is repeated.
The crankshaft 5 which is interlocked with the piston 11 via the connecting rod 15 is rotated in one direction, and the crankshaft 5 outputs the power of the engine 1 to the outside.

According to the above construction, while the piston 11 is on the top dead center side, the fuel 29 injected from the fuel injection port 28 is injected.
Is supplied to the crank chamber 3 through the communication passage 32 and the cylinder hole 8 on the crank chamber 3 side.

Therefore, in the subsequent process following this, in addition to the fuel 29 being directly injected into the combustion chamber 21 to be supplied with the fuel 29, the fuel 29 supplied to the crank chamber 3 is also supplied. It is supplied to the combustion chamber 21 with the air 19 pre-compressed through the fresh air passage 22. Therefore, even in the high speed and high load condition, a sufficiently large amount of the fuel 2 is supplied to the combustion chamber 21.
9 is supplied, and a mixture containing less unvaporized fuel is formed in the combustion chamber 21 before the spark plug 23 is discharged.

When the fuel 29 is directly injected into the combustion chamber 21 by the fuel injection valve 30, the air 19 and the fuel 29 in the combustion chamber 21 are injected into the piston 1 by the injection.
Therefore, it is necessary to increase the injection pressure by the fuel injection valve 30. However, according to the above configuration, the fuel injection port 28 is located above the upper end of the cylinder hole 8. Since it is also located on the crank chamber 3 side, the injection pressure of the fuel injection valve 30 can be made smaller by that amount, so that the fuel pump for pressurizing the fuel 29 can be made compact, and this pump is low-priced. Can be

The following drawings show the second to fourth embodiments. Each of these embodiments has many points in common with the first embodiment in terms of configuration and operation. Therefore, these common elements are denoted by common reference numerals in the drawings, description thereof will be omitted, and different points will be mainly described.

(Second Embodiment)

FIGS. 5 and 6 show a second embodiment.

According to this, the injection direction of the fuel 29 through the fuel injection port 28 is bifurcated upward and downward, that is, the injected fuel 29 is the upper and lower injected fuel 29a. , 29b.

Therefore, when the fuel 29 is directly injected into the combustion chamber 21, the fuel 29 is more atomized and the concentration of the fuel 29 in the combustion chamber 21 becomes more uniform to promote the combustion. It

Since the upper injected fuel 29a is directed toward the spark plug 23 and forms a rich air-fuel mixture around the spark plug 23, the low temperature startability is improved, and the stratified charge combustion is performed at low speed and low load. It enables fuel economy and exhaust gas purification. Further, the lower injected fuel 29b is directed toward the head portion 12 of the piston 11, which effectively cools the head portion 12 that tends to become hot due to combustion and reduces the amount of unvaporized fuel before ignition.

Further, the fuel 29 is passed through the fuel injection port 28 and the like.
Is injected, the upper injected fuel 29a is transferred to the piston 1
The first head portion 12 collides with the back surface side of the first head portion 12 and, as a result, the head portion 12 which is likely to be heated to a high temperature is effectively cooled. On the other hand, the upper injected fuel 29a is immediately vaporized.

The lower injected fuel 29b is eliminated,
If the amount of the upper injection fuel 29a is increased, the head portion 1
The cooling of 2 is more effective, and the mixture is more reliably formed in the crank chamber 3.

(Third Embodiment)

7 to 9 show a third embodiment.

According to this, the fuel injection port 28 is communicated with the combustion chamber 21 through the downstream end of the fresh air passage 22, that is, the end on the cylinder hole 8 side. In this case, since the position of the fuel injection port 28 is closer to the crank chamber 3 side, even when the piston 11 approaches the top dead center, the fuel 29 is passed from the fuel injection port 28 through the communication passage 32 to the crank chamber 3. The communication passage 32 is a notch extending upward from the lower edge of the skirt portion 13 so that the communication passage 32 can be supplied to the third side.

According to the above construction, when the fuel 29 is injected into the crank chamber 3 side through the fuel injection port 28, the fuel 29 passes through the fresh air passage 22 and the pre-compressed air 19 toward the combustion chamber 21. They collide with each other and become more atomized, thus promoting combustion in the combustion chamber 21.

In the above case, the crank angle at which the fuel 29 can be directly injected into the combustion chamber 21 by the fuel injection valve 30 is θ.
= 120 ° to 240 °, the same as above.
9 can be supplied when θ = 90 ° to 270 °.

(Fourth Embodiment)

FIG. 10 shows a fourth embodiment.

According to this, the engine 1 has four cycles, the fresh air passage (pressurizing passage) 22 shown in the first embodiment is provided with another reed valve 36, and this fresh air is provided. Intake valve 3 for opening and closing the outlet of the passage (pressurizing passage) 22
7 are provided. Further, an exhaust valve 38 that opens and closes the inlet of the exhaust passage 25 is provided. In addition, 39 is a throttle valve.

The fresh air pressurized in the crank chamber 3 for each revolution of the crankshaft 5 is stored in the fresh air passage (pressurization passage) 22 by another reed valve 36, and the crankshaft 5 makes two revolutions. It is guided into the combustion chamber 21 through an intake valve that opens and closes every time.
In the 4-cycle engine 1, the fuel injection port 2
8 and the inside of the crank chamber 3 are in communication with each other through the communication passage 32 opening to the skirt portion 13 of the piston 11, all four of the explosive expansion process, the exhaust process, the intake process, and the compression process. During the process, it is possible to inject fuel from the fuel injection valve 30 into the crank chamber 3. The direct fuel injection into the combustion chamber 21 is performed during the intake process and the compression process while the head portion 12 of the piston 11 is on the crankshaft 5 side of the fuel injection port 28.

In the present embodiment, the fresh air passage (pressurizing passage) 22 is formed in both the cylinder 7 and the cylinder head 50. However, the crank chamber 3 and the cylinder head 50 are provided in a pipe line independent of the cylinder 7. Inside fresh air passage (pressurized passage)
22 may be connected. In this case, the other reed valve 36 arranged at the outlet from the crank chamber 3 is covered with the end of the pipe.

In the two embodiments shown in FIGS. 1 to 6, the fuel injection port 28 may be arranged near the outlet of the fresh air passage (scavenging passage) 22. As a result, in the explosive combustion process, the volume in the combustion chamber 21 is sufficiently increased and the pressure is reduced, and then the fuel injection port 28 is exposed in the combustion chamber 21. It will not come into contact with gas, improving durability. Further, in this case, when the communication passage 32 is formed near the piston ring 51 of the skirt portion 13 of the piston 11 as illustrated, the head portion 12 of the piston 11 passes through the fuel injection port 28 and the communication passage is formed. When 32 coincides with the fuel injection port 28, injection is performed immediately.

That is, when the piston 11 is at the intermediate position between the top dead center and the bottom dead center, the fuel can be injected into the crank chamber 3 during either the descending operation or the ascending operation or both. Further, by forming the communication passage 32 as a long hole in the skirt portion 13 in the reciprocating direction, it is possible to inject into the crank chamber 3 for a long period of time, as in the embodiment of FIG. 7. The long hole can increase the rigidity and strength of the end portion of the skirt portion 13 as compared with the head portion 12 in the embodiment of FIG. 7.

In the two embodiments shown in FIGS. 1 to 8, the communication passage 32 may be arranged anywhere on the circumference of the skirt portion 13 if the piston pin boss portions 11a on both sides of the piston 11 are avoided. . That is, it may be provided on the side of the exhaust passage 25 perpendicular to the piston pin 14. In this case, the fuel injection valve 30 includes the exhaust passage 25 and the cylinder head 5.
It will be arranged in the middle region of 0. The crankshaft 5 is preferably rotated counterclockwise in the figure. As a result, the communication passage 32 is not arranged in the skirt portion 13 on the side to which the lateral pressure is applied in the explosion expansion stroke, but the communication passage 32 is arranged on the exhaust passage 25 side. Therefore, the rise of the lateral pressure is prevented and the durability of the piston 11 is improved.

Also in the embodiment shown in FIG. 10, the communication passage 32 has the piston pin boss portions 1 on both sides of the piston 11.
It may be arranged anywhere on the circumference of the skirt portion 13 if it avoids 1a. In the case of injecting fuel from the direction perpendicular to the piston pin 14 as shown in the drawing, a small hole is provided in the portion of the connecting rod 15 on the small end side where fuel is injected to reduce the lubricating load on the small end bearing. Good.

[0062]

【The invention's effect】

The effects of the present invention are as follows.

According to the first aspect of the present invention, a cylinder is provided so as to project from the crankcase, and a piston is slidably fitted in a cylinder hole of the cylinder in the axial direction thereof, and a crank chamber of the crankcase is burned in the cylinder hole. A fresh air passage communicating with the chamber is provided, and by sliding the piston, the air outside is temporarily sucked into the crank chamber and pre-compressed, and the pre-compressed air passes through the fresh air passage to burn the combustion. In the fuel injection supply type engine in which a fuel injection port is formed in the cylinder so that the fuel can be supplied to the combustion chamber from the outside of the cylinder toward the combustion chamber, the piston moves to the top dead center. During the ascending stroke, after the head portion of the piston has passed through the fuel injection port,
A communication passage for communicating the fuel injection port with the crank chamber is formed in the skirt portion of the piston.

Therefore, in the prior art, when the piston reaches the top dead center side, the fuel injection port is closed by the piston and the injected fuel cannot be sufficiently supplied to this combustion chamber. According to the invention, while the piston is on the top dead center side, the fuel injected from the fuel injection port can be supplied to the crank chamber through the communication passage and the cylinder hole on the crank chamber side.

Therefore, in the subsequent process following this, in addition to being directly injected into the combustion chamber to supply the fuel to the combustion chamber, the fuel supplied to the crank chamber passes through the fresh air passage. It is supplied to the combustion chamber together with pre-compressed air, and therefore, even at high speed and high load, a sufficiently large amount of fuel is supplied to the combustion chamber, and thus the desired engine output can be obtained. Becomes

Moreover, the fuel supplied to the crank chamber is sufficiently vaporized and sufficiently mixed with air when it is pre-compressed in the crank chamber and thereafter supplied to the combustion chamber through the fresh air passage. As a result, a uniform mixture having a low concentration is obtained.

Therefore, even if a part of the air-fuel mixture is directly discharged to the outside of the engine due to the "blowing phenomenon" in the two-cycle engine, the amount of the discharged fuel can be small. Further, it is possible to prevent incomplete combustion due to insufficient vaporization of fuel in the 4-cycle engine.

According to the second aspect of the present invention, the fuel injection port is communicated with the combustion chamber through the fresh air passage.

Therefore, when the fuel is injected to the crank chamber side through the fuel injection port, the fuel collides with the precompressed air passing through the fresh air passage toward the combustion chamber,
More atomized.

Therefore, a desired engine output is secured by, for example, promoting combustion in the combustion chamber.

[Brief description of drawings]

FIG. 1 is a side sectional view of a first embodiment.

FIG. 2 is a diagram illustrating an operation in the first embodiment.

FIG. 3 is a front view of a piston according to the first embodiment.

FIG. 4 is a diagram showing a relationship between a crank angle, exhaust gas, an opening / closing state of a fresh air passage, and a fuel injection timing in the first embodiment.

FIG. 5 is a diagram corresponding to FIG. 1 in a second embodiment.

FIG. 6 is a diagram corresponding to FIG. 2 in the second embodiment.

FIG. 7 is a diagram corresponding to FIG. 1 in the third embodiment.

FIG. 8 is a diagram corresponding to FIG. 2 in the third embodiment.

FIG. 9 is a diagram corresponding to FIG. 3 in the third embodiment.

FIG. 10 is a diagram corresponding to FIG. 1 in the fourth embodiment.

[Explanation of symbols]

 1 Engine 2 Crankcase 3 Crank Chamber 5 Crankshaft 7 Cylinder 8 Cylinder Hole 9 Shaft Center 11 Piston 12 Head Part 13 Skirt Part 19 Air 21 Combustion Chamber 22 Fresh Air Passage (Scavenging Passage, Pressurizing Passage) 28 Fuel Injection Port 29 Fuel 30 Fuel injection valve 32 Communication passage

Claims (2)

[Claims] Claim: What is claimed is: 1. A new cylinder provided on a crankcase, the piston being slidably fitted in the cylinder hole of the cylinder in the axial direction thereof so that the crank chamber of the crankcase communicates with the combustion chamber of the cylinder hole. An air passage is provided, and when the piston slides, air outside is temporarily sucked into the crank chamber and precompressed, and the precompressed air is supplied to the combustion chamber through the fresh air passage. Thus, in the fuel injection type engine in which the fuel injection port capable of supplying the injected fuel from the outside of the cylinder toward the combustion chamber is formed in the cylinder, the piston is in the upward stroke to the top dead center, After the head portion of the piston has passed through the fuel injection port, a communication passage that connects the fuel injection port to the crank chamber is formed in the skirt portion of the piston. Fuel injection-fed engine. 2. The fuel injection type engine according to claim 1, wherein the fuel injection port is communicated with the combustion chamber through a fresh air passage.