JPH10288135A - Idle air intake control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent attachment of combustion products on an idle air intake control valve by restraining generation of an eddy current in an idle air intake passage and preventing backflow of the combustion products in the idle air intake passage. SOLUTION: An idle air intake passage 4 to communicate the upstream side and the downstream side of an air intake control valve 3 set in an air intake passage 2 of an internal combustion engine 2 is provided and an idle air intake control valve 5 is provided in the middle of it on this device. A throttle part 41 is provided in the inside of the air intake passage 4 on the downstream of the idle air intake control valve 5, and an inwall surface of the throttle part 41 and an inwall surface of the idle air intake passage 4 on it upper and downstream are connected to each other on a smooth surface with no step. Intrusion of a pulsation flow is restrained by ventilation resistance of the throttle part 41, it is shaped with no step, an eddy current is restrained, intake air is straightened and generation of backflow is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an idle intake control device for controlling an intake air amount during an idling operation of an internal combustion engine, and more particularly to an idle intake passage structure.

[0002]

2. Description of the Related Art It is known that an idle intake control device is installed in an intake system of an internal combustion engine to adjust the intake flow rate during idling (for example, Japanese Patent Application Laid-Open No. 4-1467). As shown in FIG. In the figure, an internal combustion engine 1 includes:
Air is supplied from the outside through an intake pipe 22 from an intake pipe 21.
Has an intake branch pipe 22a corresponding to the number of cylinders of the internal combustion engine that communicates with each cylinder of the internal combustion engine 1. The space in the intake pipe 21 and the intake chamber 22 forms an intake passage 2, and air from the outside is metered by an intake adjustment valve 3 installed in the intake passage 2, and the internal combustion engine 1 It is sucked into each cylinder.

[0003] The intake passage 2 is provided with a bypass passage communicating the upstream side and the downstream side of the intake adjustment valve 3, and is used for idling of the internal combustion engine when the intake adjustment valve 3 is fully closed. The idle intake passage 4 is provided. An idle intake adjustment valve 5 is disposed in the middle of the idle intake passage 4, and regulates an intake flow rate supplied to the internal combustion engine 1 through the idle intake passage 4.

[0004]

The idle intake passage 4 is normally formed inside a thick passage wall of the intake passage 2 as shown in FIG. 5, and has a bent portion or a step. Often in shape. Generally, a vortex is likely to be generated downstream of the idle intake adjustment valve 5 due to a change in the passage area, and similarly, the passage diameter increases in the idle intake passage 4 downstream of the idle intake adjustment valve 5 in the traveling direction of the intake air. If there is such a step, a vortex flows around here.
In the configuration of FIG.
1 and 62, and the passage diameter changes greatly before and after that. Therefore, as shown by the arrows in the figure, the vortex flow immediately after the idle intake adjustment valve 5 and immediately after the steps 61 and 62 7 easily occurs.

[0005] On the other hand, in FIG. 4, combustion products are accumulated in the intake chamber 22 downstream of the intake control valve 3 due to blowback from the internal combustion engine 1, and the combustion products are accumulated in the intake chamber 22. The pulsating flow and the vortex 7 in FIG.
Therefore, there is a problem that the vehicle enters the idle intake passage 4. That is, the combustion products enter the vicinity of the outlet of the idle intake passage 4 due to the pulsation in the intake chamber 22 when the intake control valve 3 is largely opened, and
When the intake control valve 3 is almost fully closed, the idle intake passage 4
When the vortex shown in FIG. 5 is generated, the vortex rides and flows backward in the idle intake passage 4. And there was a possibility that this combustion product might adhere to the idle intake adjustment valve 5.

Accordingly, the present invention suppresses the generation of a vortex in the idle intake passage, prevents the combustion products from flowing back in the idle intake passage, and deposits the combustion products on the idle intake control valve. The purpose is to prevent.

[0007]

According to a first aspect of the present invention, an idle intake control device communicates between an upstream side and a downstream side of an intake air regulating valve installed in an intake passage of an internal combustion engine, and An idle intake passage that serves as an intake passage during idle operation of the engine; and an idle intake adjustment valve that is provided in the middle of the idle intake passage and that adjusts an amount of intake air supplied to the internal combustion engine through the idle intake passage. ing. In the present invention, a throttle portion is provided in the idle intake passage downstream of the idle intake adjustment valve, and a step is formed between an inner wall surface of the throttle portion and an inner wall surface of the idle intake passage upstream and downstream thereof. Not connected with a smooth surface.

In the above configuration, the throttle portion is provided in the idle intake passage.
Intrusion of pulsating flow when the engine is under high load is suppressed. Also, since the above-mentioned constricted portion has a shape having no step before and after it,
The vortex does not occur due to the installation of the throttle, and even if vortex occurs downstream of the idle intake adjustment valve, it is rectified by the throttle, so that the vortex does not extend to the downstream area of the throttle. Absent. Therefore, the generation of the backflow in the idle intake passage is suppressed, and in addition, the intake flow accelerated when passing through the throttle portion prevents the combustion products from entering the upstream side of the throttle portion. To prevent combustion products from reaching the idle intake adjustment valve,
Adhesion of combustion products can be prevented.

In the configuration of the second aspect of the present invention, the narrowed portion is formed to have a shape that gradually increases in diameter from the substantially central minimum diameter portion toward the upstream and downstream sides. By adopting such a shape, the rectifying effect of the throttle and the effect of preventing the intrusion of the pulsating flow can be maintained, and the throttle portion having no step can be easily realized.

In the third aspect of the present invention, the inclination angle of the wall surface on the upstream side of the minimum diameter portion is set to be larger than the inclination angle of the wall surface on the downstream side in the narrowed portion. By increasing the inclination angle on the upstream side, the flow rate of the intake air passing through the throttle portion is increased, and the effect of preventing the intrusion of the combustion products described above can be enhanced. Further, it is preferable that the inclination angle on the downstream side is smaller than this so that the flow on the downstream side of the throttle section is not disturbed by the high-speed intake flow.

According to a fourth aspect of the present invention, the cross-sectional area of the minimum diameter portion is set to 80% or less of the smaller cross-sectional area of the idle intake passage upstream and downstream. In addition, it is set to be equal to or larger than the maximum opening area of the idle intake adjustment valve. Within this range, it is possible to obtain the above-described effect of the installation of the throttle portion and to secure a necessary intake air amount at the time of idling.

According to a fifth aspect of the present invention, when the position of the minimum diameter portion is the maximum intake pulsation width Δp [kPa] in the intake passage downstream of the intake adjustment valve, the minimum diameter portion is determined. Is set so that the distance x [mm] of the center locus of the passage cross section from to the downstream end of the idle intake passage is x ≧ 1.5 · Δp. At this time, by securing a distance equal to or greater than the amplitude of the combustion product due to the pulsation downstream of the throttle, it is possible to prevent the combustion product from invading upstream of the throttle.

According to a sixth aspect of the present invention, the entire surface of the inner wall surface of the idle intake passage downstream of the intake regulating valve is formed of a smooth surface having no steps or corners.
As a result, the generation of the vortex is further suppressed, and the effect of preventing the backflow is improved.

[0014]

FIG. 1 shows a first embodiment of the present invention. In the figure, an intake adjustment valve 3 for adjusting an intake amount supplied to an unillustrated internal combustion engine is provided in an intake passage 2. The intake air flows in the intake passage 2 from the left to the right in the drawing. After passing through the intake adjustment valve 3, the intake air passes through a passage in an intake chamber (not shown) to the internal combustion engine. Inhaled.

The intake passage 2 has a part of the passage wall formed thick in the vicinity of the intake adjustment valve 3, and an approximately communicating portion between the upstream side and the downstream side of the intake adjustment valve 3. U
A letter-shaped idle intake passage 4 is provided. At an intermediate portion of the idle intake passage 4, an idle intake adjusting valve 5 for adjusting an intake amount at idling is provided.

In the present invention, a throttle portion 41 for rectifying the flow in the passage and suppressing the backflow is provided in the idle intake passage 4 downstream of the idle intake adjustment valve 5. The throttle portion 41 has a shape that gradually increases in diameter from the substantially central minimum diameter portion 41a toward the upstream side and the downstream side, and is formed between the inner wall surface of the throttle portion 41 and the idle intake passage 4 upstream and downstream thereof. The wall surface is configured to be connected with a smooth surface having no step.

Here, the narrowed portion 41 has a minimum diameter portion 41.
The inclination angle of the wall surface on the downstream side is formed to be gentle with respect to the inclination angle of the wall surface on the upstream side in FIG. When the inclination angle on the upstream side is large, the flow passing through the throttle portion is easily accelerated, and the effect of preventing the intrusion of the fuel product is enhanced. The downstream side is preferably gently enlarged along the intake air flow.

The narrowed portion 41 is usually provided with a minimum diameter portion 41a.
Is 80% or less of the smaller area of the passage cross-sectional area b and the downstream passage cross-sectional area c of the upstream of the idle intake passage 4, and the maximum opening area of the idle intake control valve 5. It is formed so as to be as described above. By setting the passage cross-sectional area of the minimum diameter portion 41a to be equal to or larger than the maximum opening area of the idle intake adjustment valve 5, a sufficient intake amount in an idle state can be secured. In addition, in order to obtain a sufficient rectifying effect in practical use, it is desirable that the passage cross-sectional area of the minimum diameter portion 41a be 80% or less of the passage cross-sectional areas b and c of the idle intake passage 4. Therefore, it is preferable to appropriately set the passage cross-sectional area of the minimum diameter portion 41a so that the minimum required flow rate is secured within the above range. In addition, using a carbon tracer, visualization of the intake passage in an actual internal combustion engine was conducted, and as a result of examining the range of the throttle portion in which carbon, which is a combustion product, did not flow backward, it was found that the throttle area was 80% or less, Carbon intrusion to the side was almost prevented.

The position of the minimum diameter portion 41a is usually determined when the maximum intake pulsation width in the intake passage 2a downstream of the intake control valve 3 is Δp [kPa].
It is preferable to set the distance x [mm] from 1a to the rear end portion 42 of the idle intake passage 4 so that x ≧ 1.5 · Δp. Here, the distance x is the distance of the center locus of the passage cross section. Generally, particles such as carbon have a higher density than air, so that the lower the pulsation frequency, the larger the amplitude for the same air pulsation. In an automobile engine, the number of rotations frequently used is about 2000 rpm, and the correlation between the pulsation width Δp at that time and the amplitude L of the reciprocating motion of carbon as a combustion product is examined. 5.
It was found that the relationship Δp was established. Therefore, x ≧ L
Then, a distance equal to or greater than the amplitude of the combustion product due to the pulsation in the intake passage 2a can be secured downstream of the throttle portion.
Combustion products can be prevented from entering the upstream side of the throttle section 41.

It is preferable that the entire surface of the inner wall surface of the idle intake passage 4 downstream of the idle intake adjustment valve 5 is formed of a smooth surface having no steps or corners. In the present embodiment, the bent portion 43 of the passage is formed into a curved surface, and the rectifying action is further enhanced.

According to the above configuration, the flow resistance in the throttle section 41 prevents the fuel product from entering the upstream side of the throttle section 41 due to the pulsation in the intake chamber. In addition, by setting the aperture portion 41 at an appropriate position, the above effect can be more effectively exerted. Further, since no step is formed before and after the restricting portion 41, no vortex is generated due to the restricting portion 41, and further, the air flows backward from the intake chamber by the accelerated intake flow passing through the restricting portion 41. Intrusion of fuel products can be prevented. In addition, since the entire passage downstream of the idle intake adjustment valve 5 has no steps or corners, eddy currents are less likely to occur. Can be prevented from spreading.

Thus, the generation of the backflow toward the idle intake control valve 5 can be suppressed to prevent the combustion products from adhering to the idle intake control valve 5, and an idle intake control device excellent in controllability can be provided. realizable.

FIGS. 2A and 2B show a second embodiment of the present invention. In the present embodiment, the idle intake passage 4 is bent in the radial direction of the intake passage 2 at a position downstream of the idle intake adjustment valve 5 so as to be formed in a substantially arc shape along the outer periphery of the intake passage 2. I have. The above-mentioned aperture part 4
1 is the distance x (the distance of the center locus of the passage cross section) between the minimum diameter portion 41a and the downstream end portion 42 of the idle intake passage 4 and the minimum diameter portion 41 in the substantially arc-shaped passage 44.
The cross section a is formed so as to be within the predetermined range shown in the first embodiment.

According to the above configuration, the length of the idle intake passage 4 can be made longer, and the effect of suppressing intrusion of combustion products is high. In addition, since the passage is formed in an arc shape, the passage has a shape with few steps and corners, and is excellent in a backflow prevention effect.

The idle intake passage 4 having the above structure is formed by molding a passage portion before and after the idle intake regulating valve 5 and the substantially arc-shaped passage 44 by casting, and forming a through hole 45 communicating the both. And can be easily molded.

In each of the above-described embodiments, the above-described effect can be obtained if at least one throttle portion is provided for one idle intake passage. However, the number is not particularly limited and may be plural. Further, a plurality of idle intake passages may be provided or may be branched in the middle.

When there are a plurality of idle intake passages, one or more throttles are required in each passage.
(A) and (b) show a third embodiment of the present invention. In this embodiment, the idle intake passage 4 is branched in the middle, and a similar substantially arc-shaped branch passage 44 'is provided at a symmetric position of the substantially arc-shaped passage 44 in the second embodiment. It is. Also in this branch passage 44 ', a throttle portion 41' is formed at substantially the same position as the throttle portion 41 of the passage 44.

As described above, when a single intake passage cannot secure a sufficient flow rate, the branch passage 44 'is provided in the idle intake passage 4 to increase the total flow rate. Also in the above configuration, the same effect as in each of the above embodiments can be obtained by providing the throttle portion in each intake passage.

[Brief description of the drawings]

FIG. 1 is an overall cross-sectional view of an idle intake control device according to a first embodiment of the present invention.

FIG. 2A is an overall sectional view of an idle intake control device according to a second embodiment, and FIG. 2B is a sectional view taken along line AA of FIG.

FIG. 3 (a) is an overall sectional view of an idle intake control device according to a third embodiment, and FIG. 3 (b) is A′-A ′ of FIG. 3 (a).
It is a line sectional view.

FIG. 4 is a schematic sectional view of an intake system of an internal combustion engine provided with a conventional idle intake control device.

FIG. 5 is an overall sectional view of a conventional idle intake control device.

[Explanation of symbols]

 Reference Signs List 2 intake passage 2a downstream intake passage 3 intake adjustment valve 4 idle intake passage 41 throttle section 41a minimum diameter section 42 bent section 5 idle intake adjustment valve

Continuing on the front page (72) Inventor Yasuyuki Kawabe 14 Iwatani, Shimowakaku-cho, Nishio-shi, Aichi Prefecture Inside Japan Automotive Parts Research Institute Co., Ltd. (72) Inventor Koichi Gomi 1 Toyota-cho, Toyota-shi, Toyota-shi, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Takashi Fukunaga 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Inventor Tadashi Akiyama 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation

Claims (6)

[Claims] 1. An idle intake passage which communicates between an upstream side and a downstream side of an intake control valve installed in an intake passage of an internal combustion engine, and serves as an intake passage at the time of idling of the internal combustion engine. An idle intake control valve that is provided in the middle and adjusts an amount of intake air supplied to the internal combustion engine via the idle intake passage. An idle intake control device, characterized in that a throttle portion is provided in the throttle portion, and an inner wall surface of the throttle portion and an inner wall surface of the idle intake passage upstream and downstream of the throttle portion are connected by a smooth surface having no step. 2. The idle intake control device according to claim 1, wherein the throttle portion has a shape having a substantially central minimum diameter portion and a diameter gradually increasing toward the upstream and downstream sides of the minimum diameter portion. 3. The idle intake control device according to claim 2, wherein in the throttle section, the inclination angle of the wall surface on the upstream side of the minimum diameter portion is larger than the inclination angle of the wall surface on the downstream side. 4. A sectional area of the passage of the minimum diameter portion is not more than 80% of a smaller passage sectional area of a passage sectional area of the idle intake passage upstream and downstream thereof, and the idle intake regulating valve is The idle intake control device according to claim 2, wherein the idle intake control device is set to be equal to or larger than the maximum opening area. 5. The position of the minimum diameter portion is defined by the maximum intake pulsation width in the intake passage downstream of the intake control valve by Δp [kP
a), the distance x (m) of the center locus of the passage cross section from the minimum diameter portion to the downstream end of the idle intake passage
5. The idle intake control device according to claim 2, wherein m] is set so as to satisfy x ≧ 1.5 · Δp. 6. The idle according to claim 1, wherein the entire surface of the inner wall surface of the idle intake passage downstream of the idle intake adjustment valve is formed of a smooth surface having no steps and corners. Intake control device.