JPH07259705A - Device for incylinder fuel injection - Google Patents

Abstract

PURPOSE:To enhance engine performance at the time of low, medium and high load in the device for in-cylinder fuel injection where fuel is injected toward a combustion chamber within a cylinder. CONSTITUTION:The device is equipped with a fuel injection valve 15 injecting fuel toward a combustion chamber 13 within a cylinder 6, and with an ignition plug 18 whose discharge section 17 is faced to the combustion chamber 13. A divergent angle adjusting means is provided, which makes a divergent angle of injected fuel by the fuel injection valve 15 variable. The divergent angle shall be small at the time of low and medium load, and large at the time of high load.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine mounted on an automobile or the like, and more particularly to a cylinder provided with a fuel injection valve for directly injecting fuel toward a combustion chamber in the cylinder. The present invention relates to an internal fuel injection device.

[0002]

2. Description of the Related Art A two-cycle internal combustion engine is provided with a fuel injection valve for injecting fuel directly toward a combustion chamber in its cylinder, and an ignition plug whose discharge portion faces the combustion chamber. is there.

When the internal combustion engine is driven, fuel is injected into the air compressed in the combustion chamber by the fuel injection valve, and an air-fuel mixture is generated in the combustion chamber. Next, the mixture is ignited by the discharge of the spark plug,
The internal combustion engine is made to output power by being burned.

[0004]

In the above case, the output is small when the internal combustion engine is at low and medium loads, so the air-fuel ratio (A / F) is usually increased to increase the intake air into the combustion chamber. A relatively small amount of fuel is used compared to the amount of air.

By the way, in this case, the fuel injected into the combustion chamber tends to be lean as a whole, so that ignitability is deteriorated and engine performance may be deteriorated.

On the other hand, when the internal combustion engine is under high load, a large output is required. Therefore, normally, the value of the air-fuel ratio is reduced to
A relatively large amount of fuel is used compared to the amount of intake air.

In this case, however, an extremely rich air-fuel mixture layer is apt to occur only in a part of the combustion chamber, which slows down the combustion speed, and in this case also, the engine performance may deteriorate.

[0008]

SUMMARY OF THE INVENTION The present invention has been made paying attention to the above circumstances, and in a cylinder fuel injection device having a fuel injection valve for injecting fuel toward a combustion chamber in a cylinder, The purpose is to improve the engine performance at each of medium and high loads.

[0009]

The in-cylinder fuel injection device of the present invention for achieving the above object includes a fuel injection valve 15 for injecting fuel 14 toward a combustion chamber 13 in a cylinder 6,
When the discharge part 17 is provided with the spark plug 18 facing the combustion chamber 13, the angle adjusting means 42 for varying the spread angle of the injected fuel 40 by the fuel injection valve 15 is provided, and the spread angle is set to low and medium. Small angle α under load
In addition, a large angle β is set when the load is high.

[0010]

[Operation] The operation of the above configuration is as follows.

When the internal combustion engine 1 has a low or medium load, the value of the air-fuel ratio is usually increased to make the fuel 14 relatively less than the intake air 29 to the combustion chamber 13. At this time, the fuel injection valve 15 is used. Since the spread angle of the injected fuel 40 injected by is set to a small angle α, the injected fuel 40 is maintained as a rich air-fuel mixture layer.

Therefore, the discharge performance of the discharge portion 17 of the spark plug 18 with respect to the injected fuel 40 improves the ignitability.

On the other hand, when the internal combustion engine 1 has a high load,
The fuel 14 is relatively increased compared to the intake air exhaust 30 into the combustion chamber 13 by reducing the value of the air-fuel ratio. At this time, the spread angle of the injected fuel 40 injected by the fuel injection valve 15 is a large angle β. Therefore, the injected fuel 40 is injected into the combustion chamber 1
3 is immediately diffused overall, i.e. combustion chamber 13
It is prevented that only a part of the mixture becomes an extremely thick mixed gas layer.

Therefore, the air-fuel mixture is burned in a more uniform state.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

(Example 1)

1 to 7 show a first embodiment.

In FIG. 2, reference numeral 1 is an internal combustion engine.
The internal combustion engine 1 is a pre-compression type multi-cylinder two-cycle engine and is installed in a vehicle that is a vehicle. The arrow Fr in the figure indicates the front in the traveling direction of the automobile.

The internal combustion engine 1 has a crankcase 2, and the inside of the crankcase 2 is a crank chamber 3. A crankshaft 4 is housed in the crank chamber 3, and the crankshaft 4 is rotatably supported by the crankcase 2 about its axis.

A cylinder 6 is provided so as to project upward from the crankcase 2, and the cylinder 6 is composed of a cylinder body 7 attached to the crankcase 2 and a cylinder head 8 attached to the upper end of the cylinder body 7. Has been done. A cylinder hole 9 having a circular cross section is formed in the cylinder body 7. A piston 11 is fitted in the cylinder hole 9 so as to be slidable in the axial direction on the axis 10 thereof.
Are connected by a connecting rod 12.

The cylinder body 7, cylinder head 8,
A space surrounded by the piston 11 is a combustion chamber 13. An electromagnetic valve type fuel injection valve 15 for appropriately injecting the fuel 14 toward the combustion chamber 13 is provided, and the fuel injection valve 15 is detachably fastened to the cylinder head 8. Further, a fuel pump 16 that pressurizes the fuel 14 in a fuel tank (not shown) and supplies it to the fuel injection valve 15 is provided.

A spark plug 18 is provided so that the discharge part 17 faces the combustion chamber 13. The spark plug 18 is also detachably fastened to the cylinder head 8.

An intake port 19 is formed on the rear wall of the crankcase 2, and the reed valve 20 is formed in the intake port 19.
And the intake pipe 21 are connected in this order. A throttle valve 22 is attached to the intake pipe 21.

Around the cylinder hole 9, the crank chamber 3
From the above to the combustion chamber 13, three scavenging passages 24 extending in an arc shape are formed in the cylinder body 7. One of the scavenging passages 24 is behind the cylinder hole 9, and the other two are the same as above. It is located on the left and right of 9.

An exhaust passage 25 penetrating the cylinder body 7 from the combustion chamber 13 toward the front of the cylinder 6 is provided.
An exhaust pipe 26 is attached to the front end opening of the exhaust passage 25.

In addition, a balancer device 27 interlocking with the crankshaft 4 is attached to the lower surface side of the crankcase 2.

The fuel injection valve 15 and the spark plug 18 are
It is electrically connected to an electronic control unit 28 and automatically controlled by this control unit 28.

When the internal combustion engine 1 is driven, when the piston 11 ascends in the cylinder hole 9 from the state of substantially bottom dead center indicated by the chain double-dashed line in FIG.
In this process, the crank chamber 3 becomes negative pressure. Then, the outside air 29 is sucked into the crank chamber 3 through the throttle valve 22, the intake pipe 21, and the reed valve 20 in order. On the other hand, at the same time, the air 29 already sucked into the combustion chamber 13 is compressed by the ascending piston 11.

As shown in each drawing, before the top dead center of the piston 11, the fuel 14 is injected into the air 29 compressed in the combustion chamber 13 by the fuel injection valve 15 controlled by the controller 28. Then, the air-fuel mixture is generated in the combustion chamber 13. Immediately before the top dead center of the piston 11, the discharge of the discharge part 17 of the ignition plug 18 controlled by the control device 28 ignites and burns the air-fuel mixture to expand the gas. The piston 11 is lowered after it has passed the top dead center.

As the piston 11 descends, the air 29 sucked into the crank chamber 3 is compressed as described above,
This causes the reed valve 20 to close. When the piston 11 is further lowered, the air 2 in the crank chamber 3 is
9 is further compressed, ie this air 29 is precompressed.

While the piston 11 is descending, first, the exhaust passage 25 is opened, and the combustion gas due to the combustion is discharged as exhaust gas 30 through these, which is the "exhaust process".

From here, when the piston 11 further descends, the scavenging passage 24 opens. Then, the air 29 pre-compressed in the crank chamber 3 as described above is transferred to the scavenging passage 2
It flows into the combustion chamber 13 through 4 and this becomes a "scavenging process". In this process, the air 29 pushes out a part of the combustion gas remaining in the combustion chamber 13 into the exhaust passage 25, and the air 29 fills the combustion chamber 13, and thereafter, the air 29 fills the combustion chamber 13. It returns to the state of bottom dead center indicated by the dotted line.

From this point, the piston 11 rises again, and the above-described steps are repeated. The crankshaft 4 rotates in the direction indicated by the arrow in FIG. 2, and the internal combustion engine 1 produces power through the crankshaft 4. Output. This power is mainly used for driving the automobile.

In FIG. 4, the fuel injection valve 15 has a cylindrical nozzle case 33, and the nozzle case 33 is fitted in a circular through hole 34 penetrating the cylinder head 8. An injection nozzle 36 is formed at the end of the nozzle case 33 on the side of the combustion chamber 13 on the axis 35 of the nozzle case 33.
It opens toward 3.

Inside the nozzle case 33, the axis 35
A rod-shaped valve element 37 having a circular cross section is provided on the upper side of the valve element 37.
Are supported on the nozzle case 33 side so as to be slidable along the axis 35.

The valve element 37 is urged by a spring (not shown) to be moved in the nozzle case 33 toward the injection nozzle 36 side, and the injection nozzle 36 is closed (shown by a solid line in FIG. 4).

On the other hand, the fuel injection valve 15 has a solenoid (not shown). When this solenoid is excited by being turned on under the control of the control device 28, the valve element 37 is actuated against the spring, the injection nozzle 36 is opened, and the nozzle case 33 is pressurized and supplied. The fuel 14 is injected into the combustion chamber 13 through the injection nozzle 36 (indicated by one-dot chain line and two-dot chain line in FIG. 4).

1, 3, and 4, when the axial center 10 of the cylinder hole 9 is viewed vertically, the ceiling surface of the combustion chamber 13 is formed by a part of the lower surface of the cylinder head 8. . A concave groove 3 that opens downward in a part of the ceiling surface
9 is formed, and the concave groove 39 is substantially hemispherical and is located substantially on the axial center 10.

A portion of the ceiling surface excluding the concave groove 39 is a squish area 38. The groove 3
9, the discharge portion 17 of the spark plug 18 and the injection nozzle 36 of the fuel injection valve 15 are located near the shaft center 10 of the cylinder hole 9. The discharge part 17 and the injection nozzle 36 are located in mutually opposite directions with respect to the axis 10. The axis 35 of the injection nozzle 36 passes near the discharge part 17.

In FIG. 4, when the fuel 14 is injected by the fuel injection valve 15 through the injection nozzle 36, the injected fuel 40 is conically injected.
Further, the spread angle of the injected fuel 40 is set to a small angle α.
And an angle adjusting means 42 that is variable to any one of the large angles β.

The angle adjusting means 42 has a cam type stopper 43 supported on the nozzle case 33 side. The stopper 43 is rotatably supported about its axis and also serves as a solenoid 4 as an actuator.
It can be reciprocally rotated by 4. Also,
The solenoid 44 is electrically connected to the control device 28.

Then, as shown by the chain double-dashed line in FIG. 4, when the valve body 37 is moved and the injection nozzle 36 is opened with the stopper 43 in the "forward rotation" state, the valve body 37 injects. At a position slightly away from the nozzle 36, the movement is blocked by the stopper 43. In this case, the injected fuel 4
The spread angle of 0 is a small angle α.

On the other hand, as shown by the alternate long and short dash line in FIG. 4, when the valve body 37 is moved and the injection nozzle 36 is opened with the stopper 43 being "reversely rotated", the valve body 37 causes the injection nozzle to open. The movement of the injected fuel 4 is prevented by the stopper 43 at a position greatly separated from 36.
The spread angle of 0 is a large angle β.

A detection sensor 45 is provided to detect the driving condition of the internal combustion engine 1, such as the rotational speed of the crankshaft 4, the throttle opening of the throttle valve 22, the amount of air 29 sucked through the intake pipe 21, The detection signals of these detection sensors 45 are input to the control device 28.

Then, for example, the control device 28 determines that the internal combustion engine 1 is in the low and medium load state by the detection signal of the detection sensor 45 that the rotation speed of the crankshaft 4 is low and medium. For example, the control device 28 causes the stopper 43 to be "forwardly rotated" so that the spread angle of the injected fuel 40 is set to the small angle α.

On the other hand, for example, when the internal combustion engine 1 is under a high load due to the detection signal of the above-mentioned detection sensor 45 that the rotational speed of the crankshaft 4 is high, the control device 28
If the determination is made in step S3, the control device 28 causes the stopper 43 to "rotate back" to set the spread angle of the injected fuel 40 to the large angle β.

According to the above construction, there are the following effects.

That is, when the internal combustion engine 1 is under a low or medium load, the intake air 2 to the combustion chamber 13 is usually increased by increasing the value of the air-fuel ratio.
Although the amount of fuel 14 is relatively small compared to that of No. 9, at this time, the spread angle of the injected fuel 40 injected by the fuel injection valve 15 is set to a small angle α, so that the injected fuel 40 remains a rich mixture layer. That is, the air-fuel mixture in the combustion chamber 13 is prevented from becoming lean as a whole.

Then, the injected fuel 40 is the spark plug 1
It is supposed that the so-called stratified charge combustion can be obtained by improving the ignitability by the discharge of this discharge part 17.

On the other hand, when the internal combustion engine 1 is under high load,
The fuel 14 is relatively increased compared to the intake air exhaust 30 into the combustion chamber 13 by reducing the value of the air-fuel ratio. At this time, the spread angle of the injected fuel 40 injected by the fuel injection valve 15 is a large angle β. Therefore, the injected fuel 40 is injected into the combustion chamber 1
3 is immediately diffused overall, i.e. combustion chamber 13
It is prevented that only a part of the mixture becomes an extremely thick mixed gas layer.

Therefore, since the air-fuel mixture is burned in a more uniform state, the combustion speed is increased.

In the above case, the discharge section 17 and the injection nozzle 36 are located near each other. Therefore, the injected fuel 40 injected from the injection nozzle 36, even when the internal combustion engine 1 has a low or medium load and the air-fuel ratio is large,
Immediately after this injection, the discharge part 1 is left with a rich air-fuel mixture layer.
7 will be reached. Therefore, the ignitability is further improved.

Each amount of the injected fuel 40 is adjusted to an appropriate amount during the period when the injection nozzle 36 is opened, and this period is controlled by the controller 28.

The pressure converting means 46, FIG. 5 and FIG. 6 in FIG. 4 show modifications of the angle adjusting means 42.

According to this, the angle adjusting means 42 switches the pressure (fuel pressure) of the fuel 14 between the fuel pump 16 and the fuel injection valve 15 into two stages of "low pressure" and "high pressure". The pressure converting means 46 is provided, and the pressure converting means 46 is electrically connected to the control device 28.

If the control device 28 determines from the detection signal of the detection sensor 45 that the internal combustion engine 1 is in a low and medium load state, the control device 28 causes
The pressure converting means 46 switches the fuel pressure to "low pressure" (A portion in FIG. 5), and accordingly, the spread angle of the injected fuel 40 is set to the small angle α (FIG. 6).

On the other hand, when the internal combustion engine 1 has a high load based on the detection signal of the detection sensor 45, the control device 28
If the control device 28 determines that the fuel pressure is high, the pressure converting means 46 switches the fuel pressure to "high pressure" (see FIG. 5).
Middle portion B), and accordingly, the spread angle of the injected fuel 40 is set to a large angle β (FIG. 6).

FIG. 7 shows a modification of the shape of the injected fuel 40.

According to this, when the axial center 10 of the cylinder hole 9 is viewed in the vertical direction, the injected fuel 40 is either an elliptical injected fuel 40a having a horizontally long cross section or an elliptical injected fuel 40b having a vertically long cross section. To be done. Both 40a and 40b
Is selected by rotating the injection nozzle 36 by 90 ° around its axis 35.
This can be done by rotating and removably attaching to the cylinder head 8.

When the horizontally long elliptical injected fuel 40a is used, the horizontally long elliptical injected fuel 40a with a particularly small angle α is transferred to the scavenging passage 24 in the "scavenging process".
Is hardly affected by the air 29 that is drawn into the combustion chamber 13 through the discharge chamber 1.
7 is reached accurately, and the ignitability is improved.

On the other hand, when the vertically elongated elliptical injected fuel 40b is used, the vertically elongated elliptical injected fuel 40b having a particularly small angle α is not easily affected by the ascending piston 11, that is, stratified combustion is more obtained. It will be easier. Further, the vertically long elliptical injected fuel 40b having a large angle β has an advantage of being more uniformly diffused into the combustion chamber 13.

The following drawings show the second to sixth embodiments. Since these embodiments have many points in common with respect to the configuration and operation in the first embodiment, common reference numerals are given to the drawings and explanations thereof are omitted, and different points are mainly described. To do.

(Example 2)

FIG. 8 and FIG. 9 show the second embodiment.

According to this, the spark plug 18 is located substantially on the axis 10. For this reason, the discharge unit 17 and the injection nozzle 36 are closer to each other, so that the ignitability of the discharge unit 17 is further improved.

(Example 3)

10 and 11 show the third embodiment.

According to this, the concave groove 39 has a rectangular side cross section, and the bottom surface 39a which is the upper surface thereof is substantially flat. Further, the groove 39 has a substantially elliptical plane cross section,
One end inner peripheral surface 39b, which is the front end inner peripheral surface, has a large-diameter circular arc shape, and the other end inner peripheral surface 39c, which is the rear end inner peripheral surface, has a small-diameter circular arc shape.

The center of curvature of the one inner peripheral surface 39b is the axis 1
It is located in the vicinity of 0, and the spark plug 18 is almost the same as above.
Located on top. Further, the injection nozzle 36 is open at a corner where the bottom surface 39a of the groove 39 and one end inner peripheral surface 39b are joined.

(Example 4)

12 and 13 show the fourth embodiment.

According to this, although the concave groove 39 is similar to that of the first embodiment, the discharge portion 17 is located slightly away from the injection nozzle 36. Therefore, the injected fuel 40 injected from the injection nozzle 36 reaches the discharge unit 17 after being sufficiently vaporized. Therefore, the ignitability is improved.

In this case, in particular, when the pressure of the fuel 14 immediately before being injected from the injection nozzle 36 is low, each particle size of the injected fuel 40 is relatively large, and therefore, each inertial force is large and the discharge part is large. Exactly reach 17. Since vaporization is promoted during this period, the ignitability is improved even when the pressure of the fuel 14 is low.

(Example 5)

14 and 15 show the fifth embodiment.

According to this, the combustion chamber 13 of the piston 11
A guide groove 48 is formed on the upper surface, which is the side surface. Just before the top dead center of the piston 11 shown in FIG. 14, when the injection nozzle 36 injects the injection fuel 40 at a small angle α, the injection fuel 40 is guided and reflected by the guide groove 48, and the discharge portion It is supposed to reach 17.

According to this embodiment, since the discharge part 17 and the injection nozzle 36 are largely separated from each other, the injection fuel 40 injected from the injection nozzle 36 is sufficiently vaporized, and the same operation as that shown in the fourth embodiment is performed. Produce an effect.

In addition to this, since the top surface of the piston 11 faces the combustion chamber 13 and is apt to reach a high temperature,
When the injected fuel 40 is reflected by the guide groove 48, the vaporization is further promoted by the heat of the top surface of the piston 11, and the ignitability is improved.

(Example 6)

16 and 17 show the sixth embodiment.

According to this, although the concave groove 39 is almost the same as that shown in the third embodiment, the discharge portion 17 has the concave groove 39.
It is located at the rear end portion of the discharge unit 17 and the discharge unit 17 and the injection nozzle 36 are largely separated from each other. Therefore, the injected fuel 40 injected from the injection nozzle 36 is sufficiently vaporized, and the same effect as that of the fourth embodiment is obtained.

In addition to this, the injected fuel 40 injected from the injection nozzle 36 is guided toward the discharge section 17 by the inner surfaces of the left and right side walls of the concave groove 39. Therefore, the injected fuel 40 is sufficiently vaporized as described above, and is prevented from being diluted and supplied to the discharge unit 17. Therefore, the ignitability is sufficiently improved.

[0083]

According to the present invention, the in-cylinder fuel injection device is provided with a fuel injection valve for injecting fuel toward a combustion chamber in a cylinder, and an ignition plug whose discharge portion faces the combustion chamber. Since the angle adjusting means for changing the spread angle of the injected fuel by the fuel injection valve is provided and the spread angle is set to a small angle at low and medium loads, and a large angle at high loads, the following effects are obtained. .

That is, when the internal combustion engine is at low and medium loads, the value of the air-fuel ratio is usually increased to make the fuel relatively smaller than the intake air into the combustion chamber. At this time, the fuel is injected by the fuel injection valve. Since the spread angle of the injected fuel is small, the injected fuel is kept as a rich mixture layer,
It is prevented that the air-fuel mixture in the combustion chamber becomes lean as a whole.

Therefore, the discharge of the spark plug with respect to the injected fuel improves the ignitability and obtains so-called stratified combustion, which improves the engine performance under low and medium loads.

On the other hand, when the load of the internal combustion engine is high, the value of the air-fuel ratio is usually made small and a relatively large amount of fuel is supplied compared to the intake / exhaust to the combustion chamber. Since the spread angle of the fuel is large,
The injected fuel is immediately diffused entirely into the combustion chamber,
In other words, it is prevented that only a part of the combustion chamber becomes an extremely rich air-fuel mixture layer.

Therefore, since the air-fuel mixture is burned in a more uniform state, the combustion speed is increased and the engine performance under high load is also improved.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of FIG. 2 in Embodiment 1.

2 is a bottom view of what is shown in FIG. 1 in Embodiment 1. FIG.

FIG. 3 is an overall side sectional view of the internal combustion engine in the first embodiment.

FIG. 4 is a side sectional view showing a fuel injection valve and an angle adjusting means in the first embodiment.

FIG. 5 is a graph showing the relationship between engine load and fuel pressure in a modification of the first embodiment.

FIG. 6 is a graph showing the relationship between fuel pressure and spread angle in a modification of the first embodiment.

7 is a cross-sectional view corresponding to line 7-7 in FIG. 1 in a modification of the first embodiment.

FIG. 8 is a diagram corresponding to FIG. 1 in the second embodiment.

FIG. 9 is a diagram corresponding to FIG. 2 in the second embodiment.

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

FIG. 11 is a diagram corresponding to FIG. 2 in the third embodiment.

FIG. 12 is a diagram corresponding to FIG. 1 in Example 4.

FIG. 13 is a diagram corresponding to FIG. 2 in the fourth embodiment.

FIG. 14 is a diagram corresponding to FIG. 1 in the fifth embodiment.

FIG. 15 is a diagram corresponding to FIG. 2 in the fifth embodiment.

FIG. 16 is a diagram corresponding to FIG. 1 in Example 6.

FIG. 17 is a diagram corresponding to FIG. 2 in the sixth embodiment.

[Explanation of symbols]

 1 Internal Combustion Engine 6 Cylinder 9 Cylinder Hole 10 Shaft Center 11 Piston 13 Combustion Chamber 14 Fuel 15 Fuel Injection Valve 16 Fuel Pump 17 Discharge Section 18 Spark Plug 28 Control Device 29 Air 35 Shaft Center 36 Injection Nozzle 40 Injection Fuel 42 Angle Adjusting Means α Small angle β Large angle

Claims (1)

[Claims] 1. An in-cylinder fuel injection device comprising: a fuel injection valve for injecting fuel toward a combustion chamber in a cylinder; and an ignition plug having a discharge portion facing the combustion chamber. The in-cylinder fuel injection device is provided with an angle adjusting means for varying the divergence angle, and the divergence angle is set to a small angle at low and medium loads and a large angle at high loads.