JPH0784857B2 - Internal combustion engine intake system - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for an internal combustion engine in which a fuel injection valve is arranged in a collecting portion of intake pipes.

(Prior Art) In a fuel injection type internal combustion engine, for example, as shown in FIGS. 4 and 5, intake branch pipes 5 to 8 connected to the respective cylinders 1 to 4
The surge tank 9 is installed in the collecting part of the
There is one in which the fuel injection valve 10 is arranged.

The intake branch pipes 5 to 8 are opened at symmetrical positions in the lower portion of the surge tank 9, and the fuel injection valve 10 is arranged so that the fuel is injected from above the center of the openings 11 to 14 of the intake branch pipes 5 to 8 toward the openings 11 to 14. Is sprayed so as to be distributed in the portion shaded with an annular line in FIG. Reference numeral 15 is a throttle valve installed in an intake pipe 16 upstream of the surge tank 9 (JP-A-55-9865).
(See publication 7).

(Problems to be Solved by the Invention) However, in such a device, the intake air intake pipe
Since the surge tank 9 is provided between the intake pipe 16 and the intake branch pipes 5 to 8, when the intake air introduced from the intake introduction pipe 16 is drawn into the branch pipes 5 to 8 via the surge tank 9, the air flow There is a problem that turbulence occurs and this increases intake resistance.

Further, since the branch pipes 5 to 8 are independently opened at the lower part of the surge tank 9, and the circular openings 11 to 14 are flat portions 17 around the openings, the fuel is injected from the fuel injection valve 10. A large amount of fuel adheres to the flat portion 17. Then, when the negative pressure in the intake pipe increases due to the adhered fuel, such as during deceleration operation, the fuel vaporizes and is sucked into the engine, which causes a problem of deteriorating exhaust performance.

There is a fuel injection valve which is arranged in an intake pipe upstream of a collecting portion such as a surge tank (see JP-A-57-32050), but in this case, the same problem as described above is also caused. Has occurred.

The present invention aims to solve such problems.

(Means for Solving the Problems) The present invention arranges a fuel injection valve in the middle of the intake introduction pipe, and at the same time, according to the number of cylinders, by a partition wall extending radially from the pipe center on the downstream side of the intake introduction pipe. The branch ports are equally divided into a fan shape, and each branch port is connected to a corresponding cylinder via a branch pipe.

(Operation) Therefore, the downstream side of the intake air intake pipe is equally divided, and the respective branch pipes are connected to the substantially fan-shaped branch ports, so that the inflowing intake air from the intake air intake pipe resists from each branch port to each branch pipe. Is smoothly inhaled.

Further, since each branch port is formed in a substantially fan shape by the partition wall that extends in the radial direction from the center of the intake introduction pipe, a flat portion is not formed around each branch port, and therefore the fuel sprayed from the fuel injection valve is It is distributed and sucked into each branch pipe from each branch port without adhering.

(Embodiment) FIG. 1 and FIG. 2 are cross-sectional views showing an embodiment of the present invention and A thereof.
In the arrow view seen from the line A, 18 is an intake introduction pipe that guides air from the outside, and 19 to 22 are branch pipes that branch the downstream side of the intake introduction pipe 18 and connect to each cylinder of the engine 23. .

A throttle valve 24 is installed in a throttle chamber 24 that constitutes the intake air intake pipe 18, and one fuel injection valve 28 is arranged on the central axis of the pipe in an injection chamber 27 downstream of the throttle chamber 24 and the air chamber 26. ing.

The air chamber 26 changes the direction of the flow of the intake air, and has a curved pipe portion formed so as to project outward, for example, to keep the velocity distribution of the intake air flowing into the injection chamber 27 uniform.

Further, the injection chamber 27 is formed by a straight pipe having a circular cross section. Incidentally, 29 is a fuel passage for guiding the fuel to the fuel injection valve 28, and 30 is a pressure regulator for adjusting the pressure of the fuel.

Then, the downstream opening of the injection chamber 27 having a circular cross section is divided at equal angles by partition walls 31 to 34 radially extending from the center thereof, and branch ports 35 to 38 each having a substantially fan shape are formed. .

The partition walls 31 to 34 are formed in a thin plate shape and are provided corresponding to the number of cylinders, and the branch ports 35 to 38 are formed in the same number as the number of cylinders.

Further, the shape of the inlets of the branch pipes 19 to 22 corresponding to the branch ports 35 to 38 is formed into a substantially fan shape which is the same as that of the branch ports 35 to 38.
35-38 and the branch pipes 19-22 are connected.

In this case, assuming that the intake order of the first to fourth cylinders to which the branch pipes 19 to 22 are sequentially connected is 1st → 3rd → 4th → 2nd, the branch pipes having consecutive intake orders are connected to adjacent branch ports To be done.

The partition walls 31 to 34 forming the branch ports 35 to 38 are the branch pipes 19 to 34.
22 to 22 to form the inlet portion, they may be formed in the injection chamber 27, but they may be integrally formed on the branch pipes 19 to 22 side.

Although the injection chamber 27 and the branch pipes 19 to 22 are connected by the flanges 39 and 40, they may be integrally formed.

With such a configuration, the intake air introduced into the intake air introduction pipe 18 changes its direction in the air chamber 26 and flows into the injection chamber 27 having a circular cross section, and flows from the injection chamber 27 to the branch ports 35 to 38 on the downstream side. It is sucked into the corresponding branch pipes 19 to 22 through the corresponding branch pipes, but is equally divided by the partition walls 31 to 34 extending in the radial direction from the downstream side of the injection chamber 27 to form the branch ports 35 to 38. 35-38
Since the branch pipes 19 to 22 are directly connected to, there is no portion where the passage cross section suddenly changes unlike the surge tank of the conventional example.

Therefore, the intake air that has flowed into the injection chamber 27 is smoothly drawn into the respective branch pipes 19 to 22 from the respective branch ports 35 to 38 without causing air flow turbulence, and therefore the intake resistance can be greatly reduced.

On the other hand, fuel is sprayed from the fuel injection valve 28 arranged on the central axis of the injection chamber 27 toward the respective branch ports 35 to 28, but the respective branch ports 35 to 38 are divided into thin plate-shaped partition walls 31 to 34.
Since it was divided by and formed into a substantially fan shape, each branch port 35 to 38
There is no part where the sprayed fuel collides with, and the sprayed fuel does not adhere.

Therefore, the atomized fuel is accurately sucked into the respective branch pipes 19 to 22 from the respective branch ports 35 to 38 together with the intake air, whereby a uniform air-fuel mixture can be supplied to each cylinder.

By the way, according to the intake order of each cylinder, since the branch pipes in which the intake order is continuous are connected to the adjacent branch ports, for example, the intake air in the injection chamber 27 turns in the order of branch ports 35 → 36 → 37 → 38. While being inhaled.

Therefore, the intake air flows more smoothly with the fuel in each branch pipe.
Since it is sucked into 19 to 22, a good distribution of the air-fuel mixture can be ensured and a more uniform air-fuel mixture can be supplied to each cylinder.

In this way, intake resistance is reduced, fuel adhesion is prevented, and a uniform air-fuel mixture can be accurately supplied to each cylinder. As a result, engine output, fuel consumption, and exhaust performance can be significantly improved. .

It should be noted that the fuel injection valve 28 disposed in the injection chamber 27 changes the passage cross-sectional area between the periphery of the injection valve 28 and the downstream side. In this case, as shown in FIG. If the throttle portion 41 is provided in, the passage cross-sectional areas can be made equal, and a smoother flow of intake air can be maintained. Further, the guide cylinder 42 may be provided in the air chamber 26, and in this way, the velocity distribution of the intake air flowing into the injection chamber 27 can be made more uniform.

Further, the present embodiment is an example applied to a 4-cylinder engine, but of course it can be applied to a 3, 6, 8-cylinder engine or the like. However, when the number of cylinders is large, such as in a 6- or 8-cylinder engine, each cylinder can be divided into two groups and the present embodiment can be applied to each group.

(Effect of the Invention) As described above, according to the present invention, the downstream side of the intake pipe in which the fuel injection valve is arranged is equally divided by the partition wall extending radially from the center to form substantially fan-shaped branch ports, Since each branch port is connected to each cylinder via a branch pipe, intake resistance can be reduced, and the fuel sprayed from the fuel injection valve does not adhere to the intake port and the intake is accurately distributed from each branch port to each branch pipe. Therefore, the output of the engine, the fuel consumption, and the exhaust performance can be improved.

[Brief description of drawings]

1 and 2 are cross-sectional views showing an embodiment of the present invention and A thereof.
FIG. 3 is a cross-sectional view showing an example of the intake air introducing pipe, and FIGS. 4 and 5 are a schematic front view and a schematic plan view of a conventional example. 18 ... Intake pipe, 19-22 ... Branch pipe, 28 ... Fuel injection valve, 31-34 ... Partition wall, 35-38 ... Branch port.

Claims (1)

[Claims] 1. A fuel injection valve is arranged in the middle of an intake introduction pipe, and a branch port is divided into substantially fan-shaped parts in accordance with the number of cylinders by a partition wall extending radially from the pipe center downstream of the intake introduction pipe. And each branch port is connected to a corresponding cylinder via a branch pipe.