JPH01318756A - Intake device for internal combustion engine - Google Patents

Abstract

PURPOSE:To increase amount of intake gas and attain improvement of output torque by a method wherein an intake path is made into a multi-tube structure consisting of at least one sub intake pipe is provided approximately on a same axis in a main intake pipe, and a switching valve is provided in the sub intake pipe. CONSTITUTION:The upstream end of a main intake pipe 7 which is connected to an inlet port 10c of a 4-cycle engine 1 is connected to an air inlet 12 via an air cleaner 2a, and an air chamber having a large capacity is swellingly formed in the middle of this main intake pipe. A throttle valve 11 is provided upstream of this air chamber 13, and a fuel injection valve 15 is provided downstream of the chamber 13, respectively. A sub intake pipe 8 is provided downstream the air chamber 13 of the main intake pipe 7 along the same axis to have a double pipe structure made on this portion. An upstream opening 8b of the sub intake pipe 8 is opened inside the air chamber 13, and a switch valve 9 is provided downstream of the sub intake pipe 8. This switch valve 9 is controlled so that it is closed at a low speed rotation range and opened at a high speed rotation range.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an engine intake device that can increase the amount of intake air by utilizing the dynamic effect of the intake air column.
In particular, the present invention relates to an intake device that can increase the amount of intake air in a wide rotation range while simplifying the structure and reducing the installation space.

[Conventional technology]

Conventionally, in piston-type internal combustion engines, so-called inertial supercharging, which increases the amount of intake air by utilizing the dynamic effect of the intake air column, has been adopted in order to improve output.

In this inertia supercharging, Kancho! , the relationship between the tube cross-sectional area A9 and the engine rotational speed N at which inertial supercharging is obtained is approximately shown in the following vibration of the Helmholtz resonator.

Nrpm-K・'组77-11 Here, vll is the effective volume in the cylinder, a is the speed of sound, and K is the proportionality constant. From the above equation, to perform inertial supercharging, the pipe cross-sectional area A or the pipe length l is It is easily understood that the value should be set according to the engine speed.

On the other hand, in variable speed engines, particularly automobile engines, the number of revolutions used varies over a wide range from an idle state to a maximum number of revolutions. For this reason, in conventional automobile engines that employ inertia supercharging, the so-called tuning point, where the amount of intake air increases due to inertia supercharging, is set near the rotational speed at which the maximum torque or maximum output occurs.
As a result, with this conventional engine, of course, no increase in torque or output could be expected in areas other than the above-mentioned tuning points.

Therefore, conventionally, as an intake system that can obtain the above-mentioned inertial supercharging effect in multiple engine rotation ranges, two intake pipes are arranged in parallel, and an on-off valve is arranged in one intake pipe. However, there is one in which the valve is opened and closed depending on the engine rotation speed.

In this intake system, the cross-sectional area of the intake pipe can be switched between two stages depending on the engine speed, so high torque can be achieved in both high-speed and low-speed ranges.

[Problem that the invention seeks to solve]

However, the conventional device in which a plurality of intake passages are arranged has a problem in that it requires a large space because a plurality of intake pipes are arranged in parallel. Particularly in a multi-cylinder engine, since there are restrictions on the spacing between each cylinder, it is difficult to realize the arrangement of multiple systems as described above, and the structure tends to become complicated.

The present invention solves the above-mentioned problems with the conventional device, realizes switching of tuning points in two or more stages without increasing the installation space, and provides an internal combustion engine that can increase the amount of intake air in a wide range of engine speeds. The purpose is to provide an air intake device.

Means for Solving Problem C] The present inventor found that in order to utilize inertial supercharging in multiple stages without increasing the installation space, the intake pipes should be arranged coaxially instead of in parallel. I focused on the points.

Therefore, in the engine intake system according to the present invention, the intake passage has a multi-pipe structure in which at least one sub-intake pipe is disposed approximately coaxially within the main intake pipe, and a valve that can be opened and closed is provided in the sub-intake pipe. The valve is installed and opens and closes depending on the engine speed.

In the present invention, when the intake passage is made of three or more multiple pipes, the outer GL+ intake pipe may be extended long toward the engine side, and an opening/closing valve may be provided in the extended portion.

[Effect]

In the present invention having the above configuration, for example, if the sub-intake pipe is one double pipe, the opening/closing pulp of the sub-intake pipe is closed in the low speed rotation range. As a result, combustion air is introduced into the engine through only the ring-shaped main intake passage between the main intake pipe and the auxiliary intake pipe. Further, at high speeds, the opening/closing valve is opened, whereby combustion air is also introduced from the main intake passage and the auxiliary intake passage in the auxiliary intake pipe. the result,
Regarding the cross-sectional area of the intake passage, at low speeds the cross-sectional area of only the main intake passage is small, while at high speeds the cross-sectional area of the main and auxiliary intake passages is large. Therefore, the amount of intake air can be increased in two stages: low speed and high speed.

In the present invention, the above-mentioned cross-sectional area switching is achieved by using multiple pipes in which the main and sub-intake pipes are arranged coaxially.
Compared to the conventional parallel arrangement, the installation space can be significantly reduced, and it can be easily placed in a narrow engine room, making it highly practical.

〔Example〕

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

1 to 3 are diagrams for explaining an engine intake system according to an embodiment of the present invention, and this embodiment is an example in which the cross-sectional area of the intake passage is switched in two stages.

In the figure, l is a 4-stroke gasoline engine,
This mainly consists of cylinder block 2 and cylinder head l.
O, and inside the cylinder block 2,
A piston 3 is slidably mounted. Further, an exhaust boat 1 is provided in the combustion chamber recess 10a of the cylinder head 10.
0b and the intake boat 10c are connected to each other, and both the boats 10b are connected to each other.

An exhaust valve 4 and an intake valve 5 are disposed at the combustion chamber side opening of 10c, respectively. The valves 4 and 5 are driven to open and close by valve operating mechanisms 6a and 6b, respectively.

The main intake pipe 7 of the intake device 14 of this embodiment is connected to the intake boat 10C, and the air intake port 12 is connected to the upstream end of the main intake pipe 7 via an air cleaner 12a. Further, a large capacity air chamber 13 is integrally formed in the middle of the main intake pipe 7, and the air chamber 13 has a large capacity.
A throttle valve 11 and a fuel injection valve 15 are disposed on the upstream side and the downstream end of the fuel injection valve 3, respectively.

A sub-intake pipe 8 is disposed on the downstream side of the main intake pipe 7 from the air chamber 13 so that the axes of the sub-intake pipe 8 coincide with each other, that is, coaxially, and this portion is a double pipe. Both intake pipes 7.8 are connected together by a connecting lip 7b. Further, the upstream opening 8b of the sub-intake pipe 8 opens into the air chamber 13, and an on-off valve 9 is provided on the downstream side of the sub-intake pipe 8.

Next, the effects of the device of this embodiment will be explained.

In this embodiment, the ring-shaped space between the main intake pipe 7 and the auxiliary intake pipe 8 serves as the main intake passage 7a, and the space inside the auxiliary intake pipe 8 serves as the auxiliary intake passage 8a. Depending on the speed, the cross-sectional area of the passage is changed by switching to only the main intake passage 7a or to both the main and auxiliary intake passages 7a and 3a.

First, in the low speed rotation range, as shown in FIG.
close. Air is then drawn into the engine 1 through only the main air passage 7a. In addition, in the high-speed rotation range, the on-off valve 9
open it. Air is then drawn into the engine 1 through both the main air passage 7a and the auxiliary intake passage 8a.

In this manner, in this embodiment, the cross-sectional area of the intake passage is switched between low-speed rotation and high-speed rotation, so there are two types of cross-sectional area in the above equation.

Therefore, as shown in FIG. 3, compared to the torque curve A of the conventional engine, the torque curve B of this embodiment shows that the torque increases in the two-stage engine rotation range of low speed and high speed, and the torque can be improved over a wide range. .

In this embodiment, the switching of the cross-sectional area of the intake passage was achieved by making the main and auxiliary intake pipes 7.8 have a double pipe structure, so compared to the conventional parallel arrangement, the space for the intake passages was reduced. It can be reduced to about 1/1.4.

In the above embodiment, the passage cross-sectional area was changed in two stages, but
In the present invention, it is not limited to two stages, but can be changed to a plurality of stages, and for example, as shown in FIG. 4, it is possible to switch to three stages. In this example, in the main intake pipe 17, the first.
The second auxiliary intake pipes 18 and 20 are arranged coaxially to form a triple pipe. In this case, the first auxiliary intake pipe 18 is extended longer forward than the second auxiliary intake pipe 20, and the opening/closing valve 4 rev 19a is attached to the extended portion, and the opening/closing valve 19 of the second auxiliary intake pipe 20 is
b is attached near the downstream end.

In this embodiment, the cross-sectional area of the intake passage can be switched in three stages, and as shown in FIG. 5, the torque curve B of this embodiment increases in three stages compared to the conventional torque curve A. , it is possible to achieve high torque in almost the entire range of engine rotation.

Furthermore, since this embodiment has a triple-pipe structure, the arrangement space can be significantly reduced compared to the conventional method in which three intake pipes are arranged in parallel.

Although the above embodiment has been explained using a four-stroke engine as an example, the intake system of the present invention can of course be applied to a two-stroke engine.

〔Effect of the invention〕

As described above, according to the intake system for an internal combustion engine according to the present invention, since the intake passage has a multi-pipe structure consisting of the main and auxiliary intake pipes, the area of the intake passage can be changed, and the intake This has the effect of increasing the amount and improving the torque, and since it is a multiple tube, it has the effect of significantly reducing the installation space compared to the conventional parallel arrangement structure.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining an intake device according to an embodiment of the present invention, and FIG. 1 is a cross-sectional side view thereof;
2 is a sectional view taken along the line ■-■ in FIG. The figure is an engine speed-torque characteristic diagram for explaining the effect. In the figure, 1 is an engine, 7, 17 are main intake pipes, 8° 18.20 are sub intake pipes, 9, 198, 19b are open/close valves, and 14 is an intake device.

Claims (1)

[Claims] (1) In an intake system for an internal combustion engine in which combustion air is introduced through an intake passage, the intake passage is a multi-pipe tube formed by disposing at least one sub-intake pipe substantially coaxially within a main intake pipe. What is claimed is: 1. An intake system for an internal combustion engine, characterized in that an on-off valve is disposed in the auxiliary intake pipe.