JPH0792026B2 - Intake device for V-type multi-cylinder engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an intake system for a V-type multi-cylinder engine in which fuel is distributed from a single fuel supply system through an intake manifold. .

(Prior Art) A V-type multi-cylinder engine in which a plurality of cylinders arranged in parallel are arranged in a pair in a V-shape, and the overall height of the engine is reduced due to the inclination of the cylinders, so that the degree of freedom in mounting on a vehicle is high. Therefore, there is an advantage that the engine room can be made compact. Further, when fuel is supplied through the intake manifold using a single fuel supply device such as a carburetor or a single point injection (hereinafter referred to as SPI) as a supply source, the intake passage can be formed symmetrically from the V-shaped valley to both sides. It becomes easy to equalize the fuel distribution to each cylinder and make the intake system arrangement compact. Those having such advantages are disclosed, for example, in JP-A-60-60258 and JP-A-6-60258.
The intake device for a V-type multi-cylinder internal combustion engine of No. 0-138265 can be mentioned.

On the other hand, in the intake system of an engine, it is common to set the path from the fuel supply source to the combustion chamber so that no recess is formed from the top to the ground. The reason for this is that if a recess is formed in the middle of the path, the fuel atomizes or vaporizes insufficiently at the time of cold start or during idle operation in an environment close to it, so the fuel becomes a wall flow in the liquid state. Is often supplied to the combustion chamber at the next step, that is, at the time of acceleration when the intake air amount is relatively large, etc. As a result, the air-fuel ratio becomes overrich and the smoothness of combustion is lacking, resulting in inconvenience of drivability and an increase in the amount of emission of unburned products that pollute the atmosphere. is there.

This means that even in a V-type engine, which is advantageous in mounting on a vehicle, there are cases where the engine height is pushed up and the advantages described above cannot be fully utilized. Said patent publication Sho 60
In the intake system of -60258 and 60-138265, the branch of the intake manifold is arranged horizontally along the V-shaped valley,
The total height is kept low by placing the assembly part and the fuel supply source on the side.

However, in order to further improve the equalization of fuel distribution,
As illustrated in FIG. 3, a collecting portion a of the intake manifold a
Is installed at the center of the V-shaped valley b, and the branch c is extended with the center of the gathering portion a as the center, the branch c is arranged horizontally only for the above-mentioned reason, and the gathering portion a is the intake of the cylinder head d. It is located above the upper end of port e. The arrangement of the fuel supply device and the air cleaner is also one of the factors that influence the quality of the distribution. Ideally, the fuel supply device f is placed directly above the assembly portion, and the air cleaner g is directly attached above it. However, if it is unavoidable, an extra nose is attached to connect to the air cleaner, but this is disadvantageous in terms of performance or distribution, and is expensive.

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

(Problems to be Solved by the Invention) As described above, in the intake system of the engine, when the 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 at once. Since troubles due to improper combustion are likely to occur, in a V-type multi-cylinder engine, in which the intake manifold is provided at the center of the V-shaped valley and the branch is extended to each intake port, In view of the problem that when the fuel supply device and the air cleaner are directly connected to the upper part of the engine, the overall height of the engine is increased and the advantage of the V-shaped arrangement cannot be fully utilized. Even if a recess is formed at a low position in the center of the valley, the fuel is not accumulated, and the fuel distribution is equalized and the overall engine height can be kept low. An intake device for a cylinder engine is provided.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, an intake system for a V-type multi-cylinder engine according to the present invention has a plurality of cylinders arranged in parallel to form a pair of cylinders, and the intake ports are opposed to each other inside. In a V-type multi-cylinder engine that is arranged in a V-type, the intake manifold assembly is arranged so as to be held low in the center of the V-shaped valley, and the downstream ends of the branches that extend obliquely upward from the side surfaces of the intake manifold are arranged. A bypass that is connected to the intake port and has a loop-shaped groove formed on the bottom of the collecting portion, and that is placed in parallel with each branch at the lowest position of the groove at a position close to the opening end of each branch toward the collecting portion. Is opened, and each bypass downstream end is opened to the intake port immediately upstream of each intake valve.

(Operation) With such a configuration, in a normal operating state,
Since the fuel is sufficiently vaporized, it rides on the air flow, passes through the branch of the upward slope, and is supplied to the combustion chamber. Since the fuel supply device and the intake manifold assembly are located in the center, they are evenly distributed to each cylinder, and combustion is stabilized and smooth operation is guaranteed.

On the other hand, in the small air volume region such as during cold start, warm-up process or idling operation, the atomization and vaporization of fuel are insufficient and wall flow is likely to occur, and the branch upward gradient flows backward and accumulates at the bottom of the collecting part. However, by being collected in the loop-shaped concave groove and being sucked into the combustion chamber through the bypass that opens near the open end of each branch, the distribution to each cylinder can be equalized and accelerated. Since the fuel has not stayed until the next step such as, the fuel is taken out by the flow velocity, and the fuel does not become overrich to cause improper combustion.

That is, since there is no obstacle due to the concave portion formed in the intake system and the collecting portion can be installed lower in the V-shaped valley, the overall height of the engine can be set low even if the fuel supply device and the air cleaner are stacked immediately above, which is advantageous in mounting on a vehicle. Without loss, uniform distribution and compact layout can be realized.

(Embodiment) An embodiment of the present invention will be described below with reference to the drawings.

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

A V-type 6-cylinder engine is configured by arranging cylinder rows 1 and 2 in which three cylinders are arranged in parallel in a V-type, and an intake port 7 having an intake valve 6 interposed in a combustion chamber 5 formed in a cylinder head 4 of each cylinder. Opens. The intake port 7 is parallel to the inside of the V-shape.

The intake manifold 8 connected to each intake port 7 is arranged in a V-shaped valley 9. This collecting part 10 is for each intake port 7
It is arranged at a central position of the array lower than the upstream end of the intake port 7. Branches 11a, 11b, 11c, 11d, and
The upstream ends of 11e and 11f are open, and the downstream ends are connected to the intake port 7 of each cylinder. Therefore, each branch 11a, 11b, 11
The c, 11d, 11e, and 11f have a posture inclining upward toward the downstream side.

Next, a loop-shaped groove 13 is formed on the bottom surface 12 of the collecting portion 10 along the periphery thereof. And each branch above
11a, 11b, 11c, 11d, 11e, close to the opening end to the gathering portion 10 of 11f, the upstream end of the bypass 14a, 14b, 14c, 14d, 14e, 14f,
It opens at the lowest portion of the groove 13, and the downstream end is inclined downward and opens immediately upstream of the intake valve 6 of each cylinder intake port 7.

A fuel supply device 15 (vaporizer or SP
I) is connected, and the air cleaner 16 is further connected. In addition, 17 is a heating jacket formed under the bottom surface 12 of the collecting portion 10, and 18 is an extension in which the upstream ends of the branches 11b and 11e belonging to the intermediate cylinders of both cylinder rows 1 and 2 are extended and projected into the collecting portion 10. This is for ensuring an effective pipe length equivalent to that of other branches.

With the above configuration, in a normal operating state, the fuel supplied from the fuel supply device 15 is relatively atomized, and is in a condition where it is easily heated and vaporized by the warm water of the heating jacket 17, Complete fuel gas is distributed to each cylinder. In this case, since the branch extensions 18 make the branches 11a, 11b ... 11f substantially equal in pipe length, the negative pressure force relationship generated by the stroke of the piston is transmitted to the branches almost equally, and moreover, the fuel supply device 15 Is located at the center, the sufficiently vaporized fuel becomes an air flow and is evenly distributed to each cylinder regardless of the gradient of the branch, so that the fuel is stable and smooth operation can be obtained.

In the small air volume region such as during cold start, warm-up process or idling operation, the atomization and vaporization of the fuel are insufficient, so the flow easily follows the wall of the blinch 11a, 11b ... 11f, that is, wall flow, The fuel that does not go over the upward gradient flows back to the collecting section 10 and returns to the collecting section 10. However, since the bypasses 14a, 14b ... 14f belonging to that branch are opened nearby, they are sucked into the combustion chamber in the same row through the concave groove 13. It

Therefore, it is possible to prevent the combustion troubles that may occur when the excess fuel is brought into the combustion chamber in the next step while the fuel supply amount varies due to the wall flow and a large amount of fuel is accumulated in the concave low portion, and the minute air amount region is reduced. To even out fuel distribution.

When 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, the accuracy can be improved by controlling it with an orifice or the like. Another advantage of the bypass is that by directing the bypass downstream end, which opens to the intake port 7 immediately upstream of the intake valve 6, toward the swirl direction, the combustion speed in the low load region is increased and smooth operation is achieved even with a lean air-fuel ratio. Combustion can be obtained, and economic efficiency can be improved and harmful components can be suppressed from being discharged.

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

〔The invention's effect〕

As described above, in the intake system for a V-type multi-cylinder engine according to the present invention, the branch of the intake manifold is held low at the center of the V-shaped valley and each branch is extended obliquely upward to be connected to the intake port of each cylinder. , With a loop-shaped groove formed on the bottom surface of the collecting portion, the bypass upstream end juxtaposed to each branch is opened to the lowest groove portion, and the downstream end is opened to the intake port immediately upstream of the intake valve. The overall height of the engine can be kept low while preventing the fuel distribution imbalance in the entire operating band, which has many advantages in mounting on the vehicle.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a V-type 6-cylinder engine intake system showing an embodiment of the present invention, FIG. 2 is a plan view of an intake manifold taken along line AA in FIG. FIG. 1 is a partially cutaway front view of a V-type multi-cylinder engine having a conventional intake system. 1,2 ... Cylinder row, 3 ... Cylinder, 4 ... Cylinder head, 5 ... Combustion chamber, 6 ... Intake valve, 7 ... Intake port, 8 ... Intake manifold, 9 ... V type valley, Ten
...... Meeting department, 11a, 11b, 11c, 11d, 11e, 11f …… Branch, 1
2 ... bottom of assembly, 13 ... groove, 14a, 14b, 14c, 14d, 141e,
14f: Bypass, 15: Fuel supply device, 16: Air cleaner.

Claims (1)

[Claims] Claim: What is claimed is: 1. A cylinder array comprising a plurality of cylinders arranged in parallel, a pair of cylinders, and a plurality of cylinders arranged in a V shape with intake ports facing inward.
In a multi-cylinder engine, an intake manifold assembly is arranged in the center of a V-shaped valley so as to be set low, and the downstream end of each branch extending obliquely upward from the assembly side surface is connected to each intake port. Forming a loop-shaped recessed groove on the bottom surface of the gathering portion, at the lowest portion of the recessed groove at a position close to the opening end to the gathering portion of each branch, open the upstream end of the bypass juxtaposed to each branch, An intake system for a V-type multi-cylinder engine, characterized in that the downstream end of each bypass is opened to an intake port immediately upstream of each intake valve.