JPS63297760A - Intake device of v-shaped multicylinder engine - Google Patents

Abstract

PURPOSE:To prevent the imbalance of fuel distribution and reduce the total height of an engine by setting low the collection part of an intake manifold at the center of a V-shaped bottom spacer and connecting each branch with the intake port of each cylinder, extending aslantly upwardly. CONSTITUTION:In a V-shaped cylinder engine, the collection part 10 of an intake manifold 8 connected with each intake port 7 which is arranged in parallel inside the V-shape is arranged in a V-shaped bottom space 9. This collection part 10 is arranged lower than the upstream edge of the intake port 7 at the center position of the arrangement of each intake port 7. The upstream edge of the branch 11 (11a-11f) is opened on the side wall of the collection part 10, and the downstream edge is connected to each intake port 7. A loop-shaped recessed groove 13 is formed along the peripheral edge on the bottom surface 12 of the collection part 10, and the upstream edge of each bypass 14a-14f is opened at the lowest position of the recessed groove 13, in proximity with the opened edge to the collection part 10 of each branch 11, and the downstream edge is opened on the upstream of an intake valve 6 at each intake port 7, inclined downwardly.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention is directed to an air intake system for a type multi-cylinder engine in which fuel is distributed from a single fuel supply device through an intake manifold. Regarding.

(Prior art) A V-type multi-cylinder engine, in which a plurality of parallel cylinder rows are arranged in a V-shape, has a high degree of freedom in mounting on a vehicle because the overall height of the engine is lowered by the inclination of the cylinders. This has the advantage of making the engine room more compact. In addition, when a single fuel supply device, such as a carburetor or single point injection (hereinafter referred to as SPI), is used as a supply source and fuel is supplied through an intake manifold, the intake passage can be formed symmetrically from the V-shaped valley to both sides. It becomes easier to equalize fuel distribution to each cylinder and make the intake system more compact.

Examples of such an advantage include the intake systems for V-type multi-cylinder internal combustion engines disclosed in Japanese Patent Laid-Open No. 6060258 and No. 60-138265.

On the other hand, in the intake system of an engine, the path from the fuel supply source to the combustion chamber is generally set so that no recess is formed from top to bottom. The reason for this is that if a recess is formed in the middle of the path, the fuel will not be atomized or vaporized sufficiently during low-temperature startup or during idling in a similar environment, resulting in the fuel remaining in a liquid state and forming a wall flow. In many cases, the wall flow flows backward on the uphill slope downstream of the recess and accumulates in the recess, and the accumulated fuel is sucked into the combustion chamber at once during the next step, such as during acceleration when the amount of intake air is relatively large. This is because the air-fuel ratio becomes overrich and combustion becomes less smooth, resulting in problems such as poor drivability and increased emissions of unburned products that pollute the atmosphere. be.

This may push up the overall height of the engine even in the type II aircraft, which is advantageous for vehicle mounting, and may not be able to take full advantage of the advantages described above.

Said published patent publication No. 60-60258, 1986-13
In the intake system of No. 8265, the branches of the intake manifold are arranged horizontally along the V-shaped valley, and the collecting part and the fuel supply source are placed on the sides to keep the overall height low.

However, in order to roughly improve the equalization of fuel distribution,
As illustrated in Fig. 3, the gathering part a of the intake manifold
is installed in the center of the ■-shaped valley, and the branch C is extended with the center of this collecting part a.For the above reasons, the branch C is arranged horizontally as a limit, and the collecting part a is connected to the intake air of the cylinder head d. It is located above the upper end of port e. The arrangement of the fuel supply device and air cleaner is also one of the factors that determines the quality of distribution, and ideally, the arrangement of the fuel supply device f
Place the air cleaner Q directly above the collecting part, and install the air cleaner Q directly above it.If it is unavoidable, add an extra nose and connect it to the air cleaner.
There are disadvantages in terms of performance and distribution, and costs are high.

Therefore, if an attempt is made to adopt an ideal arrangement for fuel distribution, the overall height of the engine becomes high, and there is a problem in that the above-mentioned advantages of mounting on a vehicle cannot be fully utilized.

(Problems to be Solved by the Invention) As described above, in the intake system of an engine, when a recess is formed in the middle of the path from the fuel supply device to the combustion chamber, the fuel accumulated in the recess is sucked all at once. Troubles due to improper combustion are likely to occur in V-type multi-cylinder engines, so in V-type multi-cylinder engines equipped with an intake system in which the gathering part of the intake manifold is placed in the center of the ■-shaped valley and branches extend to each intake port, In view of this problem, in this invention, the collecting part is made into a V-shape. The purpose of this design is to prevent fuel from accumulating even when a low concave is formed in the center of the valley.The intake air for a V-type multi-cylinder engine is designed to equalize fuel distribution and keep the overall height of the engine low. It provides equipment.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, an intake system for a V-type multi-cylinder engine of the present invention pairs cylinder rows in which a plurality of cylinders are arranged in parallel, and has intake ports facing each other inwardly. In a V-type multi-cylinder engine arranged in a V-type, v1jX! The gathering part of the intake manifold is arranged low in the center of the valley, and the downstream end of each branch extending diagonally upward from the side of the gathering part is connected to each intake port, and a loop-shaped recess is formed on the bottom of the collecting part. A groove is formed, and the upstream end of the bypass installed in parallel with each branch is opened at the lowest part of the groove at a position close to the opening end to the gathering part of each branch, and the downstream end of each bypass is connected to each intake valve. The structure is such that it opens to the intake port immediately upstream of the intake port.

(Function) With this configuration, under normal operating conditions,
Since the fuel is sufficiently vaporized, it is carried by the airflow through the uphill branch and supplied to the combustion chamber. The central location of the fuel supply system and intake manifold assembly ensures equal distribution to each cylinder, stabilizing combustion and ensuring smooth operation.

On the other hand, in a small air space region such as during cold start, AM process, or idle link operation, fuel atomization and vaporization are insufficient, and it is easy to form a wall flow, which flows backwards up the branch slope and accumulates at the bottom of the collecting section. However, by being collected in a loop-shaped groove and being sucked into the combustion chamber through a bypass that opens near the open end of each branch, it is possible to equalize the distribution to each cylinder and increase acceleration. Since the fuel does not remain until the next step such as, the flow velocity will not cause the fuel to be carried out and become overrich, causing incorrect combustion.

In other words, there is no obstruction due to the recess formed in the intake system, and the gathering part can be installed low in the ■-shaped valley, so even if the fuel supply device and air cleaner are stacked on one side, the overall height of the engine can be set low, which is advantageous when mounted on a vehicle. Equalization of distribution and compact arrangement can be achieved without loss of space.

(Example) DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, explanation will be made with reference to figures showing embodiments of the present invention.

FIG. 1 is a partially longitudinally sectional front view showing an intake system of a type 6 six-cylinder engine, and FIG. 2 is a plan view of the intake manifold taken along the line A--A in FIG.

Cylinder rows 1 and 2, which have three cylinders in parallel, are arranged in a V shape to form a V
A six-cylinder engine is constructed, and an intake port 7 having an intake valve 6 interposed therebetween is connected to a combustion chamber 5 formed in a cylinder head 4 of each cylinder.

The intake ports 7 are arranged in parallel inside the V-shape.

An intake manifold 8 connected to each intake port 7 is arranged in a V-shaped valley 9. This gathering portion 10 is arranged at the center of each arrangement of the intake ports 7 and lower than the upstream ends of the intake ports 7 . Branches 11a, 11 are provided on the side wall of the collecting portion 10.
b, 11c, 11d.

The upstream ends of 11e and 11f are open, and the downstream ends are connected to the intake ports 7 of each cylinder. Therefore, each branch 11
a, 11b, 11c, 11d, 11e, and 11t are inclined upward toward the downstream side.

Next, a loop-shaped groove 13 is formed in the bottom surface 12 of the collecting portion 10 along its periphery. And each of the above-mentioned branches 11a, 11b, 11c.

Bypasses 14a, 14b, 14c are located close to the frontage ends of 11d, 11e, 11f to the collecting portion 10.

The upstream ends of the grooves 14d, 14e, and 14f open at the lowest portion of the groove 13, and the downstream ends slope downward and open immediately upstream of the intake valve 6 of each cylinder intake port 7.

A fuel supply amount W115 (carburizer or 5PI) is connected above the gathering part 10, and an air cleaner 16 is connected in an overlapping manner. In addition, 17 is a heating jacket formed under the bottom surface 12 of the gathering part 10, and 18 is both cylinder rows 1.2.
The upstream ends of the branches 11b and 11e belonging to the intermediate cylinder are extended and protruded into the gathering part 10, and are intended to ensure the same effective pipe length as the other branches.

With the above configuration, under normal operating conditions, the fuel supplied from the fuel supply device 15 is relatively atomized and is in a condition where it is easily vaporized by being heated by the hot water in the heating jacket 17. The complete fuel gas is distributed to each cylinder.

In this case, each branch 11 is
8. Since the pipe lengths of 11b...11f are approximately equal, the negative pressure force generated by the stroke of the piston is transmitted approximately equally to each branch, and the fuel supply device 15 is located in the center. Sufficiently vaporized fuel becomes an airflow and is evenly distributed to each cylinder regardless of the branch slope, resulting in stable combustion and smooth operation.

In a small air region such as during low-temperature startup, warm-up process, or idling, fuel atomization and vaporization are insufficient, resulting in a flow along the walls of branches 118, 11b...11t, that is, a wall flow. Fuel that does not easily cross the uphill slope flows backwards and returns to the gathering part 10, but since the bypasses 14a, 14b, . Inhaled into the room.

Therefore, it prevents combustion troubles caused by variations in the amount of fuel supplied due to wall flow and by bringing excessive fuel into the combustion chamber in the next step while a large amount of fuel accumulates in the low part of the recess. equalizes fuel distribution at

If there is a difference in the flow rate of the fuel flowing through the bypass due to the positional relationship with the fuel supply device, etc., the accuracy can be improved by controlling with an orifice or the like. In addition, another advantage of the bypass is that by orienting the downstream end of the bypass, which opens to the intake port 7 immediately upstream of the intake valve 6, in the swirl direction, the combustion speed in the low load region increases, resulting in a circular flow even at lean air-fuel ratios. Clean combustion can be obtained, improving economic efficiency and suppressing the emission of harmful components.

Note that the intake system of the present invention can also be applied to an in-line multi-cylinder engine.

〔Effect of the invention〕

As described above, the intake system for a V-type multi-cylinder engine according to the present invention has a gathering part of the intake manifold set low in the center of the V-shaped valley, each branch extending diagonally upward and connecting to the intake port of each cylinder. , a loop-shaped concave groove is formed on the bottom surface of the gathering part, the upstream end of the bypass arranged in parallel to each branch is opened at the lowest part of the concave FS, and the downstream end is opened to the intake port immediately upstream of the intake valve, After ensuring that there is no imbalance in fuel distribution throughout the entire operating range,
The overall height of the engine can be kept low, which has the effect of providing a significant advantage when mounted on a vehicle.

[Brief explanation of drawings]

Fig. 1 is a partially longitudinally sectional front view of a type 6-cylinder engine intake system showing an embodiment of the present invention; Fig. 2 is a plan view of the intake manifold taken along arrow A-A in Fig. 1; The figure is a partially longitudinally sectional front view of a V-type multi-cylinder engine equipped with a conventional intake system. 1.2... Cylinder row, 3 cylinders, 4... Cylinder head, 5... Combustion chamber, 6... Intake valve, 7
...Intake port, 8...Intake manifold, 9...
・V-shaped valley 0.10...Collection part, 11a, Ilb,
11c. 11d, 11e, 11f...branch, 12-...bottom of gathering part, 13 ・[! ! Groove, 14a, 14b, 14
c. 14d, 141e, 14f-... bypass, 15-...
- Fuel supply device, 16... air cleaner.

Claims (1)

[Claims] In a V-type multi-cylinder engine, which is arranged in a V-shape with cylinder rows in which multiple cylinders are arranged in parallel and arranged in a V-shape with the intake ports facing each other inward, the intake manifold is placed low in the center of the V-shape valley. , the downstream end of each branch extending obliquely upward from the side surface of the collecting part is connected to each intake port, and a loop-shaped groove is formed on the bottom of the collecting part, close to the opening end of each branch to the collecting part. At this position, the upstream ends of bypasses arranged in parallel to each branch are opened at the lowest part of the groove, and the downstream ends of each bypass are opened to an intake port immediately upstream of each intake valve. Intake system for V-type multi-cylinder engine.