JPH0355784Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an engine intake system, and particularly relates to an improvement of an engine intake system that performs intake inertia supercharging.

(Prior Art) In general, the length of the intake passage in an engine intake system is adjusted so that the pressure wave of the intake air that occurs when intake starts reaches the intake port just before the intake valve closes and forces the intake air into the combustion chamber. There is a known system in which the charging efficiency of the intake air is increased by setting the intake air and performing supercharging using the intake air inertia effect.

In order to obtain the supercharging effect using the pulsation of the intake air that occurs during the intake stroke over the entire rotation range of the engine, conventional methods have
As disclosed in the publication, a branch intake passage that supplies intake air to each cylinder of the engine, a branch passage branching from the middle of each branch intake passage, and a communication provided to communicate with each branch passage and a butterfly valve provided in each of the branch passages to open and close each branch passage, the butterfly valve opens and closes according to the rotational range of the engine to switch the effective length of the intake passage to achieve resonance of pressure waves. A system has been proposed in which the intake air filling efficiency is increased in each rotation range by changing the frequency.

(Problem to be Solved by the Invention) By the way, when a butterfly valve is provided in a conduit, it is usually provided so that the fully open position of the butterfly valve coincides with the axis of the conduit.

However, in the intake device proposed above, the butterfly valve is provided at the branching portion of the branch passage in order to prevent the volume of the branch passage from affecting the effective length of the branch intake passage when the butterfly valve is closed. For this reason, when the butterfly valve is fully open, when the butterfly valve aligns with the axis of the branch passage,
The intake flow from the branch passage flows directly into the branch intake passage along the butterfly valve at the angle of the branch part.
There is a problem in that the energy loss of the intake flow at the branch portion becomes large, and the propagation of pressure waves between the branch passage and the branch intake passage becomes poor, making it impossible to obtain a sufficient intake inertia effect.

The present invention has been made in view of the above points, and its purpose is to guide the intake flow between the branch passage and the branch intake passage by the butterfly valve when the butterfly valve is fully open. The purpose is to smooth the flow of intake air and the propagation of pressure waves in the intake passage.

(Means for Solving the Problem) In order to achieve the above object, the solution of the present invention is an engine intake system that performs supercharging by utilizing the pulsation of intake air generated during the intake stroke of each cylinder. set to target. A branch intake passage that supplies intake air to each cylinder, a branch passage branching from the middle of each branch intake passage, a communication portion provided in communication with each branch passage, and a communication portion provided in each of the branch passages. A butterfly valve is provided for opening and closing each of the branch passages, and each of the butterfly valves is set so that its fully open position is biased in the intake air flow direction at a branch portion of the branch intake passage to the branch passage with respect to the axis of the branch passage. It is structured as follows.

(Function) With the above configuration, the present invention opens and closes each of the butterfly valves according to the operating state of the engine, thereby creating an intake inertia effect according to the branch intake passage or the effective length from the cylinder to the branch passage. can be obtained selectively.

Then, when the butterfly valve is fully open, the intake flow guided from the communicating part to each branch passage is guided by the butterfly valve when it is fully open, and is deflected in the intake flow direction at the branch part of the branch intake passage to the branch passage. It joins each branch intake passage. This makes the intake flow and pressure wave propagation in each branch intake passage smooth,
A good intake inertia effect can be obtained.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

FIG. 1 shows an intake system for an engine according to an embodiment of the present invention, and 1 is an in-line 4-cylinder engine, and the engine 1 has four cylinders 2, 2, . . . arranged in its longitudinal direction. There is. Above the engine 1, a main intake passage 3 that supplies intake air to the engine 1 is arranged in a direction perpendicular to the cylinder row. Further, a volume portion 4 made of aluminum alloy is disposed diagonally above the engine 1, and is connected to the main intake passage 3 and introduces intake air from the main intake passage 3. Furthermore, 5, 5, . . . are branch intake passages that supply intake air from the volume portion 4 to each cylinder 2.
Each of the branch intake passages 5 has an upstream end opening to an inner wall of the volume section 4 facing the main intake passage 3, and a downstream end thereof leading downward along the outer wall 4a of the volume section opposite to the engine 1. After that, it is connected to each cylinder 2, and the intake air taken into the main intake passage 3 is stored in the volume part 4 to relieve its dynamic pressure, and then is evenly distributed to each branch intake passage 5. At the same time, intake interference between the branch intake passages 5 is prevented, and low-frequency intake inertia effects corresponding to each branch intake passage 5 having a long effective length are created by utilizing the pulsation of intake air generated during the intake stroke of each cylinder 2. It is made to be obtained.

Further, as shown in FIGS. 2 and 3, each of the branch intake passages 5 has a substantially constant width in the vertical direction, and a width in the lateral direction gradually increases laterally from the cylinder side toward the volume portion 4. It is formed so that it spreads out into a flat circular shape.

Furthermore, a branch passage 6, which is formed thicker than the branch intake passage 5, branches from the middle of each branch intake passage 5 directly below the volume portion 4. Each of the branch passages 6 has a length shorter than the length of the branch intake passage portion along the outer wall 4a of the volume portion, but the branch intake passage 5 of each cylinder is
are opened to a communication portion 4b that communicates with each other, and utilizes the pulsation of intake air to obtain a high-frequency intake inertia effect corresponding to each branch passage 6 having a short effective length.

Incidentally, as shown in FIG. 2, the branch passages 6, 6
. . . are integrally formed with the branch intake passages 5, 5 . . . as an intake system structure A from an aluminum alloy.

Furthermore, a butterfly valve 8 for opening and closing each branch passage 6 is provided at the branch portion 7 of each branch passage 6. Each butterfly valve 8 is controlled by a control unit 9 to which the engine speed is input. That is, in the low rotation range of the engine 1, each butterfly valve 8 closes and intake air is supplied to each cylinder 2 only from each branch intake passage 5, and the pulsation of intake air generated between each cylinder and the volume part 4 is utilized. In the high engine speed range, each butterfly valve 8 opens and each branch passage 6 communicates with the communication section 4.
The intake air inertia supercharging is performed in a high engine speed range by utilizing the pulsation of intake air generated between the cylinder 2 and each cylinder 2. The butterfly valves 8 are made of free-cutting steel and are integrally formed for each cylinder, and are formed in a shape that is slightly smaller than the passage area of the branch passage 6 made of aluminum alloy.

As a feature of the present invention, each of the above butterfly valves 8
As shown by the solid line in FIG.
When the engine rotates at high speed, the intake air flow in each branch passage 6 is guided by each butterfly valve 8 in the fully open position, so that the air flow is deflected downstream from the branch intake passage 5 to the branch passage 6. After being deflected in the intake air circulation direction S, it is made to merge into each of the branched intake passages 5.

Furthermore, as shown in FIG. 3, the engine side outer wall of the intake system structure A has a plurality of vertical ribs 10, 10 so as to increase the bending rigidity in the direction perpendicular to the cylinder rows of the intake system structure A. ...is provided.

Therefore, in the above embodiment, each butterfly valve 8 is opened and closed according to the engine speed to change the effective length of the intake passage. It can be performed.

In addition, when each butterfly valve 8 is fully open, the intake flow in each branch passage 6 is guided by each butterfly valve 8 and merges into each branch intake passage 5, so the intake flow in each branch intake passage 5 and the propagation of pressure waves. The engine speed becomes smoother, the intake inertia effect in the high engine speed range can be obtained favorably, and the intake air filling efficiency can be reliably increased.

Furthermore, since each butterfly valve 8 is made of free-cutting steel, it has excellent workability, while the volume part 4 and the intake system structure A are made of aluminum alloy, so they have good heat dissipation and the intake air This contributes to improving filling efficiency. Moreover, in order to absorb the difference in thermal expansion between each branch passage 6 and each butterfly valve 8, each butterfly valve 8 is formed in a shape that is slightly smaller than the passage area of each branch passage 6.
Regardless of the operating state of the engine 1, the butterfly valves 8, 8 are always
...can operate smoothly.

Furthermore, since each branch intake passage 5 communicates with the same volume section 4, by making the volume section 4 common, the volume section 4 can be made compact.

Furthermore, since each branch intake passage 5 is formed to become gradually flattened from each cylinder side toward the volume portion 4, the intake system structure A can be ventilated without increasing the length in the direction orthogonal to the cylinder row. The effective length of the branch intake passages 5, 5, . . . can be set to be long while making the passage diameter large and compact, and making the intake flow smooth.

In addition, the intake system component A includes a plurality of vertical ribs 10,
10... are provided, the bending moment due to the weight of the volume portion 4 can be received by the vertical ribs 10, 10..., and damage to the intake system component A can be prevented.

In the above embodiment, the case where the intake flow joins from the branch passage 6 to the branch intake passage 5 has been described, but the present invention can also be applied to the case where the intake flow branches from the branch intake passage to the branch passage. can. That is, if a butterfly valve is provided at each branch part and the fully open position of each butterfly valve is set to be deflected in the intake air flow direction at the branch part of the branch intake passage to the branch passage with respect to the axis of the branch passage, each butterfly valve When the valve is fully open, the intake air flow in each branch intake passage is guided by each butterfly valve and smoothly divided into each branch passage, and the same operation and effect as in the above embodiment can be obtained.

(Effect of the invention) As explained above, according to the engine intake system of the invention, the fully open position of the butterfly valve provided in the branch passage branching from the middle of each branch intake passage can be adjusted with respect to the axis of the branch passage. The branch intake passage is set to be deflected in the intake flow direction at the branch portion to the branch passage, and the intake flow between each branch passage and each branch intake passage is guided by each butterfly valve. The flow of intake air and the propagation of pressure waves in each branch intake passage become smooth, a good intake inertia effect can be obtained, and the filling efficiency of intake air can be improved.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention; FIG. 1 is a longitudinal side view, FIG. 2 is a perspective view of an intake system structure, and FIG. 3 is an enlarged partial sectional view thereof. 1... Engine, 2... Cylinder, 3... Main intake passage, 4... Volume part, 4b... Communication part, 5... Branch intake passage, 6... Branch passage, 8... Butterfly valve,...
Axis line, S...Intake flow direction.

Claims (1)

[Scope of utility model registration request] An intake system for an engine that performs supercharging using the pulsation of intake air generated during the intake stroke of each cylinder, which includes a branch intake passage that supplies intake air to each cylinder, and a branch intake passage that supplies intake air to each cylinder, and a branch intake passage that supplies intake air to each cylinder. The branch passage includes a branch passage, a communication portion provided in communication with each of the branch passages, and a butterfly valve provided in each of the branch passages for opening and closing each branch passage, and each of the butterfly valves is in a fully open position. An intake device for an engine, characterized in that the intake device is configured to be deflected in an intake air flow direction at a branch portion of the branch intake passage to the branch passage with respect to an axis of the branch passage.