JP2566020B2 - Fuel supply device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a fuel supply system for an internal combustion engine.

(Prior Art) As a conventional fuel supply device, there is one as shown in FIG. 7 (see JP-A-62-162770). That is, the combustion chamber 1 side openings of the intake port 5 and the exhaust port 7 provided in the cylinder head 3 so as to face the combustion chamber 1 of the internal combustion engine,
Intake valve 9 and exhaust valve 11 operated by a valve mechanism (not shown)
And are opened and closed at a predetermined timing.

Since the fuel injection valve 13 is provided so that the injection center line 17 of the spray 15 of the fuel to be injected is aimed at the center 21 of the umbrella portion 19 of the intake valve 9, the spray 15 covers the entire umbrella portion 19. Thus, the spray 15 spreads with the spray angle 23, and part of the spray 15 also adheres to the umbrella portion 19 and the inner wall 25 of the intake port 5. The inner surface wall 25 of the intake port 7 has a rough surface because it is a casting surface, and has a Ra value of 200 to 300, for example. Therefore, the fuel attached to the inner wall 25 stays as it is and becomes a wall flow.

Further, at the time of cam overlap in which the intake valve 9 starts to open, the exhaust valve 11 is also open, and at this time, the injected fuel is open as shown by the streamline 27 in FIG. It blows through the exhaust valve 11 to the exhaust port 7.

(Problems to be Solved by the Invention) As described above, in the conventional fuel supply device, since the fuel injection center line 17 is directed to the center line 19 of the umbrella portion 17 of the intake valve 9,
Spray 15 near the portion 29 of the umbrella 19 that is very close to the exhaust valve 11
Flows like a streamline 27 during cam overlap and is discharged from the exhaust valve 11 to the exhaust port 7 as a result.
This is a cause of increased HC emissions and reduced fuel consumption.

Also, the spray 15 near the lower portion 31 of the inner wall 25 of the intake port 5
Has a large adhesion to the inner surface wall 25, which has a cast surface and a rough surface, and therefore the spray 15 in the vicinity of the surface is not immediately sucked into the combustion chamber 1 as a wall flow adhered to the surface of the casting surface. Become. This wall flow changes the air-fuel ratio in each engine cycle, which causes deterioration of the combustion fluctuation rate and output reduction.

The present invention has been made in view of such conventional problems, and prevents the fuel spray from being discharged to the exhaust system in a short-circuited manner and reduces the adhesion of the intake port to the inner wall of the intake port. An object is to provide a fuel supply system for an internal combustion engine.

[Structure of the Invention] (Means for Solving the Problem) The structure of the present invention for solving the above-mentioned problems is an intake port and an exhaust port facing a combustion chamber, and an intake valve and an exhaust gas for opening and closing each port. A fuel supply device for an internal combustion engine, comprising: a valve and a fuel injection valve for injecting fuel toward a head portion of the intake valve, wherein the fuel injection valve is an exhaust valve whose injection center line is the intake valve head portion. The inner wall of the intake port, which is sprayed by the fuel injection valve, has a smooth surface roughness at least at the lower part of the wall.

(Operation) The fuel injected from the fuel injection valve is injected so that its injection center line intersects with the portion of the intake valve head portion far from the exhaust valve, and as a result, the fuel is injected into the exhaust valve of the intake valve head portion. It is difficult for the fuel spray to flow out to the near side.

Therefore, even during the cam overlap in which both the intake valve and the exhaust valve are open, the spray injected to the distant side is rarely discharged from the exhaust valve to the exhaust port in a short-circuited manner, and the cam overflow occurs. Even during the lap, the amount of unburned HC blown into the exhaust port 7 is extremely small, and the fuel is effectively used to improve fuel efficiency.

The spray injected toward the intake valve and colliding with the inner wall of the intake port collides with the lower part of the inner wall, but since the lower part of the wall has a smooth surface roughness, less fuel remains. Then, it is quickly sucked into the fuel chamber, the air-fuel ratio is stabilized in each engine cycle, and the output is improved.

(Example) Next, the Example of this invention is described based on drawing.

FIG. 1 is a longitudinal sectional view of a main part of a fuel supply system according to a first embodiment, and FIG. 2 is a main part view of FIG.

The intake port 5 and the exhaust port 7 provided on the cylinder head 3 so as to face the combustion chamber 1 have a predetermined opening by the intake valve 9 and the exhaust valve 11 which are operated by a valve mechanism (not shown). It opens and closes at the timing. Fuel injection valve 33
Is provided so that the injection center line 39 of the fuel spray 35 to be injected as shown in FIG. 1 intersects with the lower portion 41 of the umbrella portion 19 of the intake valve 9 which is far from the exhaust valve 11. There is.

As shown in FIG. 2, the cylinder head 3 is provided with two intake valves 9 and two exhaust valves 11, and the fuel injection valve 33 has two injection ports.
It is provided so as to aim at the lower portion 41 of the umbrella portion 19 of both of the individual intake valves 9. Then, in the example of FIG. 2, the injection orientation of the fuel injection valve 33 is set so that the injection center line 39 intersects with the center 43 of the lower portion 41 of the umbrella portion 19, and the spray 35 is shown in FIG. With a size of the spray angle 45 shown in FIG.

Further, the spray 35 of the fuel injection valve 33 also collides with the lower wall portion 49 of the inner wall of the intake port 5, but this lower wall portion
Smoothed the surface roughness of 49 and the lower part of the wall by the impact of spray 35
The fuel adhering to the wall 49 is swiftly flowed down by the smoothness of the lower portion 49 of the wall and sucked into the combustion chamber 1. As a method of smoothly forming the surface roughness of the lower wall 49,
For example, mechanical finishing by machining Roughness (for example, Ra value is about 2.0). In FIG. 2, reference numeral 51 is a boundary line between the intake port 5 and the surface of the casting surface which appears by processing.

Another method for smoothly forming the surface roughness of the lower wall portion 49 is shown in FIG. 3 in a longitudinal sectional view, and in FIG. 4 in a view taken along the arrow IV in FIG. In the second embodiment, a coating material 53 shown as a shaded portion in FIG. 4 is applied to the lower wall portion 49, and the coating material 53 is, for example, an alumina-based sealant having temperature resistance characteristics and fuel resistance characteristics. Is being applied. Fourth
In the figure, reference numeral 55 is a boundary line between the lower wall portion 49 smoothed by the coating material 53 and the casting surface of the intake port 5.

 Next, the operation of these two embodiments will be described.

The fuel injected from the fuel injection valve 33 has a portion 41 where the injection center line 39 is far from the exhaust valve 11 of the umbrella portion 19 of the intake valve 9.
The spray 35 does not collide with the side of the umbrella portion 19 near the exhaust valve 11. Therefore, the intake valve 9 and the exhaust valve
Even during a cam overlap in which both 11 are in the open state, the spray 35 injected to the distant side is almost never discharged from the exhaust valve 11 to the exhaust port 7 in a short circuit, and the unburned HC exhaust gas is exhausted. The amount of blow-through to the port 7 is reduced, the unburned HC concentration in the exhaust is significantly reduced, the fuel is effectively used, and the fuel consumption is improved.

The spray 35 injected toward the intake valve 9 and colliding with the inner wall of the intake port 7 adheres to the lower wall portion 49 of the inner wall having a smooth surface roughness, but stays in this lower wall portion 49. Since the amount of the air-fuel ratio decreases, the air-fuel ratio quickly flows down and is sucked into the combustion chamber 1, so that there is no variation in the air-fuel ratio between engine cycles, and the output is improved.

The third embodiment as another means for quickly removing the fuel adhering to the spray 35 against the wall lower part 49 and not accumulating there is shown in FIG. 5 in a longitudinal sectional view, and in FIG. It is shown in the view of the VI in the figure. In the third embodiment, the lower wall 49 has a sixth
The casting material 57 shown as a shaded portion in the figure is cast, and the casting material 57 is made of a material having a high thermal conductivity and is used for the lower part of the wall.
A spray that hits the bottom 49 of the wall, keeping 49 hot
35 is configured to vaporize quickly. Cast material 57
For example, copper having a thermal conductivity about twice that of the aluminum alloy forming the cylinder head 3 and having a smooth surface is used.

Therefore, the spray 35 injected from the fuel injection valve 33 is
Even if it adheres to the lower wall part 49, in combination with the smooth surface, the high temperature of the thermal conductivity makes it possible for the lower wall part 49 to rapidly evaporate and not to stay in the combustion chamber 1. As a result, the air-fuel ratio is sucked and the air-fuel ratio does not fluctuate for each engine cycle, and the output is improved.

In FIG. 6, reference numeral 59 is a boundary line between the cast material 57 and the casting surface of the intake port 5.

[Advantages of the Invention] As is clear from the above, according to the present invention, the injection center line of the fuel spray is configured to intersect with the portion of the umbrella portion of the intake valve that is far from the exhaust valve. Spray does not collide on the side closer to the exhaust valve, and even during cam overlap in which both the intake valve and exhaust valve are open, the spray injected to the part on the far side is short-circuited from the exhaust valve. Is almost never discharged to the exhaust port, the amount of injected fuel discharged to the exhaust port is extremely small, and the fuel is effectively used to improve fuel efficiency.

In addition, the fuel that collides with and adheres to the inner wall of the intake port, which has a smooth surface roughness, quickly flows down without being retained in the lower part of this wall and is sucked into the combustion chamber. Is stable and the output is improved.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a fuel supply system showing a first embodiment of the present invention, FIG. 2 is a main part view taken along the arrow II in FIG. 1, and FIG. 3 is a fuel showing a second embodiment of the present invention. 4 is a vertical sectional view of the feeding device
3 is a vertical sectional view of a fuel supply device showing a third embodiment of the present invention, and FIG.
FIG. 7 is a vertical cross-sectional view of a fuel supply device showing a conventional example. 1 ... Combustion chamber, 5 ... Intake port 7 ... Exhaust port, 9 ... Intake valve 11 ... Exhaust valve, 19 ... Umbrella part 33 ... Fuel injection valve, 35 ... Spray 39 ... Injection center line 41 …… Lower part of the intake valve umbrella 49 …… Lower wall

Claims (1)

(57) [Claims] 1. An intake port and an exhaust port facing a combustion chamber, an intake valve and an exhaust valve for opening and closing the ports, and a fuel injection valve for injecting fuel toward a head portion of the intake valve. In the fuel supply device for an internal combustion engine, the fuel injection valve is provided so that its injection center line intersects with a portion of the intake valve umbrella portion that is far from the exhaust valve, and the fuel injection valve sprays intake air. A fuel supply device for an internal combustion engine, wherein an inner wall of a port has a smooth surface roughness at least at a lower portion of the wall.