JPH045430A - Variable intake device - Google Patents

Abstract

PURPOSE:To obtain high volume efficiency in a wide rotational speed range of an engine by setting branch passages which branch and converge on the way of an intake passage, providing valves in the inlet and outlet of each of those branch passages respectively and opening closing those voltage according to the rotational speed of an engine. CONSTITUTION:Valves V1-V4 arranged at inlets and outlets of two branch passages 16, 18 are opened and closed respectively according to a specified engine speed. Respective branch passages 16, 18 can become intake passages, and pipes which connect with the intake passages, and the distance between the connecting position to the intake passages and an engine (surge tank) 12 changes. As a result, six kinds of volume efficiency that becomes the highest values in different kinds of engine speed can be obtained and a high volume efficiency is obtained in a rotation speed range from low speed to high speed of an engine 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable intake system that is capable of obtaining high volumetric efficiency over a wide engine speed range.

[Description of Prior Art] In internal combustion engines such as automobile engines, it has been known that an intake pulsation effect can be obtained by changing the length of the intake passage. In other words, it is known that when there is no branching part in the intake passage, a short intake passage produces a pulsating effect when the engine rotates at high speeds, and a long intake passage produces a pulsating effect when the engine rotates at low speeds. ing. By obtaining this pulsation effect, the volumetric efficiency of intake air is improved.

Conventionally, a variable intake device that changes the length of the intake passage when the engine speed is low and when the engine speed is high has been disclosed, for example, in Japanese Utility Model Application No. 61-99633. . This variable intake system has an intake passage between the air cleaner and the surge tank of a multi-cylinder internal combustion engine that branches into two on the way from the air cleaner to the surge tank, one of which is a long intake passage and the other is a short intake passage. Moreover, it is provided with an on-off valve that opens one of the intake passages and closes the other intake passage at the branch position.

In the device with the above configuration, when the engine speed is low, the short intake passage is closed by the on-off valve,
Open a long intake passage. On the other hand, when the engine speed is high, the open/close valve closes the long intake passage and opens the short intake passage.

In this way, the length of the intake passage is changed in response to changes in engine speed, improving volumetric efficiency.

[Problems to be solved by the invention] However, the conventionally known variable intake device can only switch between two stages, and as shown in Fig. 4, good volumetric efficiency can be obtained in all rotational speed ranges. (The case where there is no pulsation effect is defined as volumetric efficiency O). Here, in order to obtain good volumetric efficiency in all rotational speed ranges, it is conceivable to provide a large number of branch passages each having a different length, and to open and close each branch passage according to the engine rotational speed.

However, if this is done, the structure becomes complicated and the cost becomes high, and furthermore, there arises a problem that the space in the engine room is occupied.

[Object of the Invention] The present invention was made based on the fact that when a pipe with one end closed is connected in the middle of the intake passage, the natural frequency of the intake passage changes and a pulsating effect can be obtained. The present invention provides a variable intake device that can obtain high volumetric efficiency over a wide engine speed range by simply using a passage.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a plurality of branch passages each having a different length, which are provided in the middle of an intake passage that connects an air cleaner and an engine, and which branch into a plurality of branches and converge. , valves provided at the inlet and outlet of each branch passage, and control means for individually opening and closing each valve in accordance with the engine speed.

[Operation: Valve provided at the inlet and outlet of each branch passage in two locations,
Each opens and closes according to a predetermined number of rotations. As a result, each branch passage becomes an intake passage or a pipe communicating with the intake passage, and the distance between the connection position of the pipe with the intake passage and the engine (surge tank) becomes different.

As a result, it is possible to obtain six types of volumetric efficiencies that reach their maximum values at different engine speeds, and high volumetric efficiencies can be obtained in the engine speed range from low speed to high speed.

[Example] Next, the present invention will be explained based on the drawings.

FIG. 1 is a schematic diagram of an embodiment of a variable intake device according to the present invention. The air cleaner 10 and the surge tank 12 of the multi-cylinder internal combustion engine are connected to an introduction passage 14 on the air cleaner 10 side.
and a first passage 16 that branches into two from the introduction passage 14.
They are also connected through an intake passage consisting of a second passage 18 and a merging passage 20 where the first branch passage 16 and the second branch passage 18 merge. Here, the length of one of the first branch passages 16 is set shorter than the length of the other second branch passage 18.

A valve Vl is provided at the inlet (upstream side) of the first branch passage 16, and a valve V2 is provided at the outlet (downstream side). On the other hand, a valve (3) is provided at the inlet (upstream side) of the second branch passage 18, and a valve (v4) is provided at the outlet (downstream side). These valves Vl, V2. V3. V4(
7) Opening/closing is controlled by computer 22. The merging passage 20 is equipped with a throttle valve 24 . The surge tank 12 communicates with a multi-cylinder engine 28 via a manifold 26.

Next, valves Vl, V2. V3. The opening/closing operation of V4 will be explained based on FIGS. 2 and 3.

When the engine speed is in the region (lowest speed) shown in Figure 3, the four valves Vl, V2°, V3. Close only valve 2 of V4 and open the other valves. In the area of ■ where the rotation speed is higher than that, only valve ■1 is closed,
The other valves are opened (. In the region of ■ where the rotation speed is higher than that, valves V1 and V2 are closed, and valves V3 and V4 are opened (.

In the area of ■ where the rotation speed is higher than that, only valve ■4 is closed and the other valves are open (. In the area of ■ where the rotation speed is higher than that, only valve ■3 is closed and the other valves are open (. In the region of ■ where the rotation speed is high, valve V3
．． Close V4 and open valves Vl and V2 (.

First, in the region (■), the air flows through the relatively long second branch passage 18.
The first branch passage 16 becomes a pipe with an open upstream side where it branches from the second branch passage 18 .

Therefore, the volumetric efficiency in this tilted castle becomes the solid line (1) in FIG. In the region (2), air passes through a relatively long second branch passage 18, and the first branch passage 16 becomes a tube with an open downstream side where it merges with the second branch passage 18. Therefore, the volumetric efficiency in this region (■) becomes the solid line (2) in FIG. The difference between the region (■) and the region (■) is that when a pipe with one end closed is connected to an intake passage of the same length, a pulsating effect is obtained at lower rotation speeds as the connecting part moves away from the surge tank 12. .

In the region (2), both of the first branch passages 16 are closed, so the intake passage becomes a passage without a pipe, that is, a passage consisting of the introduction passage 14, the relatively long second branch passage 18, and the merging passage 20. Therefore, the volumetric efficiency in this region (■) becomes the solid line (3) in FIG. The difference between the regions of ■ and ■ and the region of ■ is that when a pipe with one end closed is connected to the intake passage and when the pipe is not connected, when the pipe is connected, a pulsation effect occurs at low rotation speeds. By obtaining.

In the region (2), air passes through the relatively short first branch passage 16, and the second branch passage 18 becomes a tube with an open upstream side where it branches from the first branch passage 16. Therefore, the volumetric efficiency in this region (■) becomes the solid line (4) in FIG. In the region (2), air passes through the relatively short first branch passage 16, and the second branch passage 18 becomes a pipe with an open downstream side where it joins the first branch passage 16. Therefore, the volumetric efficiency in this region of ■ is
Figure 3 fruit! (5) becomes. In the region (2), since both second branch passages 18 are closed, the intake passage becomes a passage without a pipe, that is, a passage consisting of the introduction passage 14, the first branch passage 16, and the merging passage 20.

Therefore, the volumetric efficiency in this region (■) becomes the solid line (6) in FIG.

In this way, in each engine speed range, the four valves Vl, V2 . V3. By opening and closing V4 as appropriate, it is possible to create a short intake passage or a long intake passage, or to provide a pipe with one end closed at a different connecting position between each length of intake passage, thereby creating a large number of intake passages. This is to obtain the natural frequency of the entire passage. As a result, the solid lines (1) and (
2), (3).

A volumetric efficiency connecting (4), (5), and (6) can be obtained. That is, the volumetric efficiency connecting this solid line is + (assumed to be O when there is no pulsation effect) in almost all engine speed ranges.

In the above embodiment, two branch passages are formed in the middle of the intake passage, but the number of branch passages may be greater than that.

[Effects of the Invention] As described above, according to the variable intake device according to the present invention,
A branch passage that branches and merges in the middle of the intake passage is provided,
A valve is provided at the inlet and outlet of each of these branch passages, and the valves are opened and closed according to the engine speed to obtain high volumetric efficiency in each engine speed range of the engine.The natural frequency of the intake passage is can be produced. As a result, high volumetric efficiency can be obtained over a wide engine speed range.

In addition, branch passages in the middle of the intake passage can be used as intake passages or as pressure propagation pipes, and with a small number of branch passages, it is possible to obtain several times the number of different pulsation effects, so it is possible to create a pulsating effect in a narrow space. Moreover, it is economical.

[Brief explanation of drawings]

Fig. 1 is a schematic configuration diagram showing an embodiment of the variable intake device according to the present invention, Fig. 2 is a table showing the opening/closing state of each valve in the engine speed range, and Fig. 3 is the volumetric efficiency characteristic of the present invention. 4 are conventional volumetric efficiency characteristic diagrams. 10...Air cleaner, 12...Surge tank, 14...Introduction passage, 16...First branch passage, 18...Second Branch passage, 2o/old/
・Merge passage, 22... Computer, 28...
...Engine, Vl, V2. V3. V4-old-valve.

Claims (1)

[Claims] A plurality of branch passages with different lengths that branch out and converge in the middle of the intake passage that connects the air cleaner and the engine, valves provided at the inlet and outlet of each of these branch passages, and each valve connected to the engine. 1. A variable intake device comprising control means that individually opens and closes depending on the rotational speed.