JPH05149204A - Intake tube for engine - Google Patents

Abstract

PURPOSE:To obtain an intake tube which disperses fuel uniformly over the whole intake air at the low speed rotation of an engine without degrading the performance of the engine at the high speed rotation of the engine. CONSTITUTION:Unevenness ranges 14, 15 whose surfaces are of numerous uneven shapes are formed in the wall surface 13a of an intake passage 13 in an intake tube 3 for engine. It is thereby possible to keep the flow of intake air in a weak turbulence condition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine intake pipe.

[0002]

2. Description of the Related Art An engine intake pipe supplies intake air such as combustion air and air-fuel mixture into a cylinder from an intake passage of the engine through an intake port of the engine.

In order to increase the output of the engine, it is necessary to increase the amount of intake air supplied into the cylinder.

Therefore, conventionally, the wall surface of the intake passage is generally formed to be smooth with the intention of reducing the flow resistance of the intake air in the intake passage.

[0005]

By the way, when the wall surface of the intake passage is smooth as described above, the intake air which has been stopped in the intake passage at the beginning of the intake stroke due to the low speed rotation of the engine is Since it is slowly inhaled inside, the intake flow is close to laminar flow (hereinafter simply referred to as laminar flow)
Will be supplied into the cylinder.

In general, the output of the engine is affected by the mixed state of fuel such as gasoline in the intake air, which is the same as in the beginning of the intake stroke at the low speed rotation of the engine. Is.

Known methods of supplying fuel to intake air include a method of injecting fuel by an injector on the downstream side of the intake passage and a method of atomizing and supplying fuel on the upstream side of the intake passage by a carburetor. In any of the above methods, under the above-mentioned conditions of the engine, the fuel is not sufficiently dispersed in the intake air supplied into the cylinder.

That is, in the former case, the fuel from the injector is supplied by being injected at a constant pressure in the direction intersecting the streamline of the intake air, and the motion inertia of the intake air and the motion inertia of the fuel particles are balanced. Therefore, it is not possible to physically disperse an equal amount of fuel to each part of the intake of fuel particles.

Further, in the latter case, since the intake air containing the fuel atomized by the carburetor temporarily becomes almost stationary in the intake pipe, the fuel particles contained in the intake gas are unevenly distributed in the lower part of the intake pipe. This is because it tends to happen.

Since the intake air is supplied to the intake port in the laminar flow state as described above, the uneven distribution of the fuel in the intake air is supplied to the cylinder as it is.

Therefore, in any of these cases, it is difficult to obtain good combustion of fuel in the engine under the above conditions.

The present invention has been made on the basis of such a background. When the engine is rotating at a high speed, the performance of the engine is less likely to deteriorate, and when the engine is rotating at a low speed, fuel is supplied to the entire intake air. The purpose of the present invention is to provide an intake pipe in which the air is uniformly dispersed.

[0013]

In order to achieve this object, the invention according to claim 1 forms a large number of small uneven areas on the wall surface of the intake passage of the engine intake pipe. It is characterized by

[0014]

According to the first aspect of the present invention, even when the intake air that has been stopped in the intake passage is slowly drawn into the cylinder at the beginning of the intake stroke when the engine is rotating at a low speed,
Since the concavo-convex region is formed on the wall surface of the intake passage, the flow of intake air reaching the intake port is in a weak turbulent state.

Therefore, even if the fuel supplied to the intake air is unevenly distributed, the fuel is agitated by the turbulent flow components and dispersed throughout the intake air.

Since the surface of the concavo-convex area is made into a large number of small concavo-convex shapes, the intake air mainly flows inside the concavo-convex area at a high speed when the engine is rotating at a high speed. The contact area with the engine is small, the intake efficiency is not reduced, and the engine performance is not reduced.

Therefore, it is possible to provide the intake pipe in which the performance of the engine is not deteriorated when the engine rotates at high speed, and the fuel is uniformly dispersed throughout the intake air when the engine rotates at low speed.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings. First, an outline of an engine equipped with an intake manifold will be described as an embodiment.

In FIG. 2, 1 is an engine and 2 is an intake manifold.

The engine 1 is a multi-cylinder engine having four cylinders and is a so-called fuel injection engine.

The intake manifold 2 is integrally formed by casting and has four intake pipes 3. An engine side bracket 4 is provided at one end of each intake pipe 3 and each intake pipe 3 is provided.
A surge tank side bracket 5 is integrally formed at the other end of the.

The intake manifold 2 is supported by attaching the engine side bracket 4 to the engine 1. The surge tank 6 is attached to the surge tank side bracket 5 of the intake manifold 2.

A throttle valve device 7 is attached to the opening end 6a on one end side of the surge tank 6, and an air cleaner 8 is supported via the throttle valve device 7.

An injector 11 is installed on the engine side bracket 4 of the intake manifold 2 for each cylinder of the engine 1 to inject and supply fuel into intake air.

A fuel tube 12 extending from a fuel tank (not shown) is connected to each of these injectors 11, and fuel pressurized to a predetermined pressure is supplied to each injector 11. Computer-controlled, engine 1 with the right amount of fuel at the right time
It is designed to be injected and supplied into each cylinder.

On the other hand, the amount of air taken in as intake air from the air cleaner 8 is controlled by the opening degree of the throttle valve 7a by operating an accelerator pedal (not shown) and taken into the surge tank 6, and the air in the surge tank 6 is controlled. Is sucked into the cylinder from the intake port of each cylinder through the intake passage 13 of each intake pipe 3.

Then, a fuel mixture such as gasoline is injected and supplied from each injector 11 into the air supplied through each intake pipe 3 to generate an air-fuel mixture.

Details of the intake manifold 2 mounted on the engine 1 as described above are mainly as shown in FIGS. The intake manifold 2 has a symmetrical shape with respect to the center line (C-C line) of FIG. 3, and one end side thereof is not shown in FIG.

An intake passage 13 communicating with the intake port of each cylinder of the engine 1 is formed inside each intake pipe 3 of the intake manifold 2 (see FIG. 3), and a wall surface of the intake passage 13 is formed. Includes the first and second uneven regions 1
4, 15 are formed (see FIGS. 1 and 4). In the figure, the line O-O is the center line of the intake passage 13.

These first and second uneven regions 14,
Reference numeral 15 denotes an area in which the surface shape of the wall surface of the intake passage 13 is formed into a large number of small irregularities. In this embodiment, as shown in more detail in FIGS. Is formed by arranging small circular concave portions 16 of the above.

That is, in the first and second uneven regions 14 and 15, the recess 16 has a diameter d of about 3 m.
The depth is set to m to 5 mm and the depth is set to about 2 mm to 3 mm, and the concave portions 16 are densely arranged with a space dimension of 2d.

As a result, in these first and second uneven regions 14 and 15, as shown in FIG. 6, the wall surfaces 13a and the recesses 16 are alternately located in the intake passage 13, and the surfaces are uneven. Is formed in.

The concave portions 16 of the first and second concave-convex regions 14 and 15 having such a structure are shown in FIG. 7 and will be described below, when the intake manifold 2 is cast, the casting core 21.
It was formed at the same time using.

That is, in FIG. 7, reference numeral 22 denotes a sand mold of the intake manifold 2, which has an upper mold 23 and a lower mold 24.

As shown in FIG. 8, the casting core 21 is molded by filling core sand between the upper and lower molds 25 and 26 and pressurizing the core sand.

On the mold surfaces of the upper and lower molds 25, 26,
In order to form the recess 16 with the casting core 21,
A large number of molding recesses 27 are formed in correspondence with the recesses 16, whereby the core sand is placed above and below the molding dies 25, 26.
The convex portion 28 is simultaneously formed on the surface of the casting core 21 by being pressurized with.

Since the convex portion 28 is thus formed on the surface of the casting core 21, the convex portion 28 does not interfere with the upper and lower molds 25 and 26, and It is necessary that the upper and lower molds 25, 26 can be removed from the mold without damage.

Note that, in FIG. 8, arrows indicate the demolding directions of the upper and lower molds 25, 26.

Therefore, in this embodiment, the convex portion 28 is formed separately in the upper part of the upper mold 25 and the lower part of the lower mold 26, and the convex part 28 is formed and the casting core 21 is removed. It is compatible with the mold.

That is, the first concavo-convex area 14 is separated by the convex portion 28 molded by the upper molding die 25, and the second concavo-convex area 15 is separated by the convex portion 28 by the lower molding die 26. Formed in.

On the wall surface 13a of the intake passage 13 of each intake pipe 3 of the intake manifold 2 cast using such a casting core 21, as described above, a large number of recesses 16 are densely packed. Uneven areas 14 and 15 are formed,
Such a wall surface 13a of the intake passage 13 is smoothly finished by honing or the like as in the conventional case (FIG. 6).
See the virtual line).

As a result, the wall surface 13a of the intake passage 13 is
It is possible to obtain the intake pipe 3 which is smooth and has the uneven regions 14 and 15 in which a large number of small recesses 16 are densely arranged.

In each of the intake pipes 3 of the intake manifold 2 obtained in this way, the upper wall surface and the lower wall surface of the intake passage 13 have a first uneven region 14 and a second uneven region 15 in general. It is arranged so as to surround the entire circumference of the intake passage 13 (see FIGS. 1 and 4).

Therefore, when the opening of the throttle valve 7 is small and the engine 1 is rotating at a low speed,
In particular, when the intake air that has been stationary in the intake pipe 3 at the beginning of the intake stroke starts to move to the engine 1 side, the moving speed of the intake air is relatively low.

In this case, in the first and second concave and convex regions 14 and 15 of the intake passage 13, the intake A moves along the wall surface 13a forming the surface and the large number of recesses 16 and the outer peripheral portion of the intake A. The portion located at is inverted by the concave portion 16 and the intake air A is in a weak turbulent state.

A required amount of fuel F is injected from the injector 11 installed on the engine side bracket 4 to the intake air A supplied from the intake pipe 3 in such a weak turbulent state, but the intake air A is the same as the conventional one. Since it is not in such a laminar flow state, even if the injected fuel F is unevenly distributed in a part of the intake air A, the fuel F is likely to be dispersed throughout the intake air A due to the turbulent flow component of the intake air A.

Further, when the engine 1 is rotating at a high speed, the intake air A is temporarily stored in the intake passage 13 for a period other than the intake stroke, and the motion inertia of the intake air A is not so great. Since the intake air A is not sucked into the engine 1 at high speed due to the large negative pressure of the engine 1, the flow of the intake air A in the intake passage 13 remains in a turbulent state, and the laminar flow state I won't.

In this case, since the intake air A in the intake passage 13 flows at a high speed along the outer peripheral portion of the intake passage 13 along the wall surface 13a of the intake passage 13, the intake air A flows linearly without passing through the large number of recesses 16. The tendency becomes stronger.

Therefore, in the first and second concave / convex regions 14 and 15 when the engine 1 rotates at high speed, the flow resistance exerted on the intake air A is small due to the presence of the respective concave portions 16, and the concave portions 16 are also provided. Since the flow of the intake air A toward the engine 1 is separated from the surface of the intake passage 13, the viscous resistance of the wall surface 13a acting on the flow of the intake air A is small, and the intake efficiency is reduced when the engine 1 rotates at high speed. There is little fear.

In the embodiment described above, the first and second concave / convex regions 14 and 15 are formed by a large number of concave portions 16. However, the present invention is not limited to this, and a large number of concave and convex regions can be formed as shown in FIG. The spherical projections 31 may be densely arranged in the same manner as the concave portions 16 to form the concave and convex regions. In this case, a recess may be formed on the surface of the casting core 21 instead of the projection 28.

Further, in the above-mentioned embodiment, the concave and convex regions are formed as the first and second concave and convex regions 14 and 15, but they may be formed as a single concave and convex region on the entire wall surface of the intake passage 13. It is also possible to form the concavo-convex region only on the local portion of the wall surface of the intake passage 13.

[0052]

As described above, according to the first aspect of the present invention, the intake air that has been stopped in the intake passage is slowly drawn into the cylinder at the beginning of the intake stroke when the engine is rotating at a low speed. In this case, since the uneven surface is formed on the wall surface of the intake passage, the flow of intake air to the intake port is in a weak turbulent state.

Therefore, even if the fuel supplied to the intake air is unevenly distributed, the fuel is agitated by the turbulent flow component and dispersed throughout the intake air.

Since the surface of the uneven area is made into a large number of small uneven areas, the intake air mainly flows inside the uneven area at a high speed when the engine is rotating at a high speed. The contact area with the engine is small, the intake efficiency is not reduced, and the engine performance is not reduced.

Therefore, it is possible to provide an intake pipe in which the performance of the engine is not deteriorated when the engine rotates at a high speed and the fuel is uniformly dispersed throughout the intake air when the engine rotates at a low speed.

[Brief description of drawings]

FIG. 1 is a sectional view taken along the line AA of FIG.

FIG. 2 is a top view illustrating how the intake manifold is mounted on the engine.

FIG. 3 is a top view of an intake manifold.

4 is a cross-sectional view taken along the line BB of FIG.

FIG. 5 is an explanatory diagram of a concave portion arrangement in an uneven region.

6 is a cross-sectional view taken along the line DD of FIG.

FIG. 7 is an explanatory view of a casting situation of an intake manifold.

FIG. 8 is an explanatory view of a molding state of a casting core.

FIG. 9 is an explanatory cross-sectional view of a concavo-convex region of a modified example.

[Explanation of symbols]

 1 Engine 2 Intake Manifold 3 Intake Pipe 13 Intake Passage 13a Wall Surfaces 14 and 15 Concavo-convex Region 16 Recess 21 Core for Casting 28 Convex 31 Spherical Protrusion

Claims (3)

[Claims] 1. A wall surface of an intake passage of an engine intake pipe,
An intake pipe for an engine, characterized in that a surface is formed with a large number of small uneven areas. 2. The engine intake pipe according to claim 1, wherein the intake pipe is made of a casting, and the concavo-convex region is formed by using a casting core having concavities and convexities formed on a surface thereof. Intake pipe. 3. The engine intake pipe according to claim 1 or 2, wherein the concave and convex area is formed by forming a large number of concave portions on a wall surface of the intake passage.