JP2537076B2 - Internal combustion engine intake system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an intake device for an engine capable of increasing an intake air amount by utilizing a dynamic effect of an intake air column, and particularly to a simple structure. The present invention relates to an intake device capable of realizing an increase in intake air amount in a wide range of rotation regions while achieving a reduction in size and an installation space.

[Conventional technology]

2. Description of the Related Art Conventionally, in a piston type internal combustion engine, a so-called inertial supercharging means for increasing the intake air amount by utilizing a dynamic effect of an intake air column has been adopted from the viewpoint of improving output.

In this inertia supercharging, the relationship between the pipe length l, the pipe cross-sectional area A, and the engine speed N at which the inertia supercharging can be obtained is approximately represented by the following Helmholtz resonator vibration equation.

Here, Vm is the effective volume in the cylinder, a is the speed of sound, and K is a proportional constant. From the above equation, it is easily understood that the pipe cross-sectional area A or the pipe length 1 may be set to a value corresponding to the engine speed in order to perform the inertia supercharging.

On the other hand, in a variable speed engine, especially in an automobile engine, the number of revolutions used varies over a wide range from the idle state to the maximum number of revolutions. Therefore, in a conventional automobile engine that employs inertial supercharging, the so-called tuning point at which the intake air amount increases due to inertial supercharging is set near the maximum torque or the maximum output rotational speed. In the conventional engine, as a matter of course, an increase in torque or output could not be expected in a region other than the tuning point.

Therefore, as an intake device capable of obtaining the above-described effect of inertia supercharging in a plurality of engine rotation regions,
For example, there is one in which two intake pipes are arranged in parallel, an opening / closing valve is arranged in one intake pipe, and the valves are opened / closed according to the engine rotation speed.

In this intake system, the cross-sectional area of the intake pipe can be switched in two steps according to the engine rotation speed, so that high torque can be realized in both high speed and low speed regions.

[Problems to be solved by the invention]

However, the conventional device having a plurality of intake passages has a problem that it requires a large space because a plurality of intake pipes are arranged in parallel. Particularly in a multi-cylinder engine, the above-described arrangement of a plurality of systems is difficult to realize and the structure tends to be complicated because of the restriction on the intervals between the cylinders.

The present invention solves the above problems in the conventional device,
An object of the present invention is to provide an intake system for an internal combustion engine that can realize two or more stages of tuning point switching without increasing the installation space and can increase the intake air amount in a wide range of engine rotation range.

[Means for solving problems]

The present inventor has noticed that in order to use the inertial supercharging in a plurality of stages without increasing the arrangement space, the intake pipes may be arranged coaxially instead of in parallel.

Therefore, the engine intake device according to the present invention has an intake passage having a multi-tube structure in which at least one auxiliary intake pipe is arranged substantially coaxially in the main intake pipe, and the upstream end opening of the auxiliary intake pipe is The main intake pipe is located in an air chamber that is bulged in the middle of the main intake pipe, and a slot valve is arranged upstream of the air chamber of the main intake pipe, and the downstream end opening of the sub intake pipe is an intake valve opening. A fuel injection valve is arranged between the downstream end opening and the intake valve opening, and a butterfly type opening / closing valve is arranged in the auxiliary intake pipe. Is closed in the engine low speed rotation range to reduce the intake passage area and generate an air flow along the inner surface of the main intake pipe, and open in the engine high speed rotation range to increase the intake passage area and reduce the main intake pipe and It is characterized in that so as to generate an air flow through the entire intake pipe.

Here, in the present invention, when the intake passage is a multiple pipe of three or more pipes, the outer sub-intake pipe may be extended to the engine side longer, and the opening / closing valve may be arranged in the extended portion.

[Action]

In the present invention having the above-described configuration, for example, if a case where the auxiliary intake pipe is a double pipe is described, the opening / closing valve of the auxiliary intake pipe is closed in the low speed rotation range. As a result, the combustion air is introduced into the engine only through the ring-shaped main intake passage between the main intake pipe and the sub intake pipe. Further, at high speed, the open / close valve is opened. As a result, the combustion air is also introduced from the main intake passage and the auxiliary intake passage in the auxiliary intake pipe. As a result, the intake passage cross-sectional area has a small cross-sectional area of only the main intake passage at low speed, and has a large cross-sectional area of the main and auxiliary intake passages at high speed. Therefore, 2 at low speed and high speed
The intake air amount can be increased in stages.

Further, in the present invention, since the switching of the cross-sectional area is realized by the multiple pipe in which the main and auxiliary intake pipes are coaxially arranged, the arrangement space can be greatly reduced as compared with the conventional parallel arrangement, and the narrow engine It is easy to place in the room and very feasible.

〔Example〕

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

1 to 3 are views for explaining an intake system for an engine 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, reference numeral 1 denotes a 4-cycle gasoline engine, which is mainly composed of a cylinder block 2 and a cylinder head 10. Inside the cylinder block 2, a piston 3 is slidably mounted. Further, the exhaust port 10 is provided in the combustion chamber recess 10a of the cylinder head 10.
b, the intake port 10c is in communication with the two ports 10b, 10c
An exhaust valve 4 and an intake valve 5 are respectively provided at the combustion chamber side openings of the. The valves 4 and 5 are opened and closed 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 port 10c, and the air intake 12 is connected to the upstream end of the main intake pipe 7 via an air cleaner 12a.
A large capacity air chamber is provided in the middle of the main intake pipe 7.
13 is integrally formed to be bulged, a throttle valve 11 is provided at the upstream side of the chamber 13, and a fuel injection valve 15 is provided at the downstream end thereof.

An auxiliary air intake pipe 8 is arranged downstream of the air chamber 13 in the main air intake pipe 7 so that the axes thereof coincide with each other, that is, coaxially, and the portion is a double pipe. Both intake pipes 7 and 8 are integrally connected by a connecting rib 7b. The upstream opening 8b of the auxiliary intake pipe 8 is the air chamber.
An opening / closing valve 9 is provided on the downstream side of the auxiliary air intake pipe 8 and opens in the inside 13.

 Next, the function and effect of the apparatus of this embodiment will be described.

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

First, in the low speed rotation range, the on-off valve 9 is closed as shown in FIG. Then, the air is taken into the engine 1 only through the main air passage 7a. In the high-speed rotation range, the on-off valve 9
Open. Then, the air flows into the main air passage 7a and the auxiliary intake passage 8
It is sucked into the engine 1 through both a.

As described above, in this embodiment, the intake passage cross-sectional area is switched between low speed rotation and high speed rotation, so that there are two cross-sectional areas in the above equation. Therefore, as shown in FIG. 3, in contrast to the torque curve A of the conventional engine, the torque curve B of the present embodiment increases the torque in two stages of engine rotation speed of low speed and high speed, and can improve the torque in a wide range. .

In the present embodiment, the switching of the intake passage cross-sectional area is realized by making the main and auxiliary intake pipes 7 and 8 into a double pipe structure. 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 in a plurality of stages, for example, as shown in FIG. 4, it can be switched to three stages. . In this example, in the main intake pipe 17,
The second auxiliary intake pipes 18 and 20 are coaxially arranged to form a triple pipe. Then, in this case, the first auxiliary intake pipe 18 is extended longer than the second intake pipe 20 forward, the opening / closing valve 19a is attached to the extension portion, and the opening / closing valve 19b of the second auxiliary intake pipe 20 is attached near the downstream end. There is.

In the present embodiment, the cross-sectional area of the intake passage can be switched in three steps. As shown in FIG. 5, the torque curve B of the present embodiment increases the torque in three steps as compared with the conventional torque curve A. It is possible to realize high torque in almost all regions of engine rotation.

Further, since the present embodiment has the triple pipe structure, the arrangement space can be significantly reduced as compared with the case where three intake pipes are arranged in parallel in the conventional method.

In the above embodiment, the four-cycle engine is described as an example, but the intake system of the present invention can be applied to a two-cycle engine.

〔The invention's effect〕

As described above, according to the intake device for the internal combustion engine of the present invention, the intake passage has the multi-pipe structure including the main and auxiliary intake pipes, and the upstream end opening of the auxiliary intake pipe is provided in the air chamber of the main intake pipe. Since it is located, the intake passage area can be switched, the intake amount can be increased in a wide range of rotation speed, the torque can be improved, and since it is a multiple pipe, the arrangement space is of the conventional parallel arrangement structure. There is an effect that can be significantly reduced compared to.

[Brief description of drawings]

1 to 3 are views for explaining an intake device according to an embodiment of the present invention, and FIG. 1 is a sectional side view thereof.
FIG. 2 is a sectional view taken along the line II-II in FIG. 1, FIG. 3 is an engine speed-torque characteristic diagram for explaining the effect, and FIG. 4 is a sectional side view showing another embodiment. The figure is an engine speed-torque characteristic diagram for explaining the effect. In the figure, 1 is an engine, 7 and 17 are main intake pipes, and 8 and 18 and 20.
Is an auxiliary intake pipe, 9, 19a and 19b are opening / closing valves, and 14 is an intake device.

Claims (1)

(57) [Claims] 1. An intake system for an internal combustion engine, in which combustion air is introduced through an intake passage, wherein the intake passage has a main intake pipe and at least one auxiliary intake pipe arranged substantially coaxially therewith. With a multi-pipe structure, the upstream end opening of the sub-intake pipe is located in an air chamber that is bulged in the middle of the main intake pipe, and a slot valve is arranged upstream of the air chamber of the main intake pipe. The downstream end opening of the sub intake pipe is positioned upstream of the intake valve opening with a space, and a fuel injection valve is disposed between the downstream end opening and the intake valve opening. A butterfly-type on-off valve is provided in the intake pipe, and the on-off valve is closed in the engine low-speed rotation range to reduce the intake passage area and generate an air flow along the inner surface of the main intake pipe, thereby increasing the engine high-speed rotation range. Then open An intake system for an internal combustion engine, characterized in that so as to generate an intake passage area and large vital main intake pipe and the sub intake pipe air flow through the entirety by the.