JP2540156B2 - 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 a V-type multi-cylinder engine in which fuel is distributed from a single fuel supply device to each cylinder through an intake manifold. Regarding the intake device.

(Prior Art) In a V-type multi-cylinder engine in which a plurality of cylinders are arranged in a pair of parallel cylinders and arranged in a V-shape, the intake ports are arranged in parallel inside the V-type opposed cylinders so that a single fuel supply device It is easy to evenly distribute the fuel to the cylinders, that is, the intake manifold in which the collecting portion is arranged in the center and which extends substantially radially and has a planch makes it easy to evenly distribute the fuel.

Generally, in the intake system of an engine, the path from the fuel supply source to the combustion chamber is set so that no recess is formed midway from the sky to the ground. The reason is that if there is a recess in the middle of the path, the fuel is likely to be a wall flow as a liquid in the minute air amount region during cold start, warm-up operation or idling operation, and backflow due to the upward gradient downstream of the recess. Then, the accumulated fuel is brought into the combustion chamber all at once at the time of acceleration when the intake air amount is relatively large in the next step, the air-fuel ratio becomes overrich, and the combustion becomes illegal. This leads to problems such as lack of smooth drivability and an increase in the amount of unburned products accompanied by air pollution.

This restriction similarly acts on the intake system of the V-type engine described above. Therefore, as shown in FIG. 5, the collecting portion b of the intake manifold a is arranged at least on the same plane with respect to the upper end of the intake port e of the cylinder head d, and the branch c is set at least horizontally. And
The fuel supply device f and the air cleaner g are directly connected on the collecting portion b to evenly distribute the fuel.

However, with the above structure, the overall engine height becomes high. Originally, the V-type engine has an advantage that the total height of the engine is reduced due to the tilt of the cylinder and the degree of freedom in mounting on the vehicle is high. However, according to the demand for equalizing fuel distribution as described above, the advantage is sufficiently obtained. It causes a problem that it cannot be used effectively.

A V-type multi-cylinder engine of the same type, in which the intake manifold assembly is arranged laterally and each branch is led out horizontally parallel to the crankshaft and connected to the intake port to keep the overall height of the engine low. Some (for example, JP-A-60-
60258 or JP-A-60-138265). Following this, if the fuel is supplied from the fuel supply device placed on the side of the central assembly, the overall height of the engine can be reduced, but the directivity of the intake air flow can reduce the fuel distribution. There is a problem that the uniformity is adversely affected.

On the other hand, the supplied fuel is required to promote atomization and vaporization, and as described above, atomization and vaporization are delayed because a sufficient flow velocity is not provided in the velocity range of the minute air amount. , Wall flow is likely to occur and even distribution is impaired. On the contrary, in the high load region, there is a demand for an intake passage with high volume efficiency as the intake air amount increases. In the engine intake system, solving this problem is also important.

The intake device disclosed in Japanese Patent Laid-Open No. 60-60258 is provided with two long and short branches adapted to a high speed region and a low speed region, but it is structurally complicated.

(Problems to be Solved by the Invention) As described above, in the V-type multi-cylinder engine including the intake manifold in which the collecting portion is placed in the center and the branches are radially extended, the fuel is evenly distributed and the total height of the engine is reduced. In view of the problem that there are conflicting restrictions between the two requirements of the ratio, the present invention is intended to solve this problem, and to supply fuel from the horizontal direction to the collecting portion. Provided is an intake device for a V-type multi-cylinder engine which lowers the overall height of the engine, promotes atomization and vaporization of fuel in all operating regions, distributes fuel evenly to each cylinder, and improves engine output performance. It is a thing.

[Structure of Invention]

(Means for Solving the Problems) In order to achieve the above object, the intake system for a V-type multi-cylinder engine according to the present invention is a V-type multi-cylinder engine.
The collecting portion is located in the center of the mold space, and an intake manifold is provided so as to connect the downstream ends of each of the planches that extend in four directions from the collecting portion to each intake port. Above the collecting portion, the intake air is tangentially and horizontally. Stacked ring-shaped swirl chambers with passages
A piston valve that is vertically slidable is inserted into the inner circumference of the swirl chamber so that it can be opened and closed, and the opening of the slit can be changed. The spring is mounted elastically to give upward biasing force to increase the slit opening.

(Operation) With this configuration, the air-fuel mixture supplied from the fuel supply device is introduced into the ring-shaped swirl chamber from the tangential direction and swirls, and is jetted from the cylindrical slit to the collecting portion. . In this case, since the swirling flow in the horizontal direction passes through the slit and swirls in the centripetal direction of the collecting portion,
It is agitated and becomes a turbulent flow, which promotes atomization and vaporization, and at the same time, there is no biased directivity for each branch and the distribution is equalized.

At the same time, the piston valve moves up and down in response to the manifold negative pressure, and atomization and vaporization of fuel are promoted by controlling the opening area of the slit. That is, since the negative pressure is high during idling operation, the piston valve is pulled down to the maximum to minimize the slit opening, and the jet flow velocity is increased to promote atomization. In the middle load and high load regions, the negative pressure decreases, the equivalent amount of the spring force raises the piston valve, opens the slit, and secures the jet outlet that obtains the volumetric efficiency that matches the intake air amount at that time,
Keep the flow rate constant to improve atomization.

In this way, atomization and vaporization of fuel are promoted in all operating regions, wall flow is reduced, and each cylinder can be evenly distributed along the air flow, stable combustion is obtained, and discharge of unburned components is suppressed. At the same time, the engine output performance is improved. In addition, it is possible to shorten the total height of the engine, which is advantageous for mounting on a vehicle.

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

FIG. 1 is a vertical sectional front view of a V-type 6-cylinder engine intake system, FIG. 2 is a plan view taken along the line AA in FIG. 1, and FIG. 3 is an enlarged vertical sectional front view.

Cylinder rows 1 and 2 in which 3 cylinders are arranged in parallel are arranged in a V-shape and V
A type 6 cylinder engine is constructed. In a combustion chamber 5 formed in a cylinder head 4 of each cylinder 3, an intake port 7 having an intake valve 6 interposed is formed facing the inside of the V-shape.

The intake manifold 8 connected to each intake port 7,
Six branches 11 are extended substantially radially from a circular gathering portion 10 placed at the center of the V-shaped space 9 shown in FIG.

A circular ring-shaped swirl chamber 12 is concentrically placed on the collecting portion 10. The swirl chamber 12 and the collecting portion 10 are communicated with each other by a cylindrical slit 13 formed in a lower portion of the inner circumference of the swirl chamber 12. A piston valve 14, which is always biased upward by a spring 15, is vertically slidably fitted on the inner peripheral surface of the swirl chamber 12. The lower end of the piston valve 14 increases or decreases the opening degree of the slit 13 by vertical displacement. 16 is the diaphragm,
Reference numeral 17 is a diaphragm chamber cover, 18 is a negative pressure passage, and 19 is a differential pressure control orifice with the atmosphere.

The swirl chamber 12 has an intake passage 20 extending in the vertical direction of the V-shaped space 9.
However, as shown in FIG. 2, they are connected in a tangential direction of the swirl chamber 12, and a fuel supply device 21 (carburetor or single point injection) is connected to the upstream end of the intake passage 20.

With the above configuration, the fuel supply device 21
Air-fuel mixture supplied from the swirling chamber 12 passes through the intake passage 20.
To the collecting portion 10 through the slit 13 while swirling. The jet flow concentrates while swirling on the axis of the collecting portion 10, is well stirred, and becomes a turbulent flow.
The fuel is evenly distributed to the combustion chambers 5 in each cylinder 3 with no biased directivity.

At this time, the piston valve 14 responds to the intake negative pressure transmitted to the collecting portion 10 to control the opening of the slit 13. Since the negative pressure is strong during idling, the spring 15
The piston valve 14 is pulled down to the stopper full by the flange 22 and the step portion 23 of the diaphragm chamber against the force of, and the slit 13 has the minimum necessary opening degree. At this time, the amount of intake air is small and fuel atomization is insufficient. However, since the opening degree of the slit 13 is small, the jet flow velocity to the collecting portion 10 is high, and atomization is promoted.

In the medium load region, the negative pressure decreases, and the equivalent force of the spring 15 raises the piston valve 14 to increase the opening of the slit 13. Since the amount of intake air is increasing, the flow velocity of the jet is kept constant and atomized without impairing the volumetric efficiency.

Further, in the high speed load region, the negative pressure approaches the atmospheric pressure, the piston valve 14 rises to the upper limit, and the opening degree of the slit 13 is greatly expanded. A sufficient ejection area is secured to obtain high volumetric efficiency, and the intake air amount is maximized at this time, so the fuel is sufficiently atomized and distributed to each cylinder by the turbulent flow that occurs naturally.

FIG. 4 shows another embodiment in which a spring 24 for pushing up the piston valve 14 is placed in the collecting portion 10.
The action is the same, and the fuel ejected from the swirl chamber 12 collides with the spring 24 and serves for atomization.

As described above, since the ejection opening area to the collecting portion 10 is variably controlled in proportion to the intake air amount, atomization and vaporization of fuel are promoted without impairing volume efficiency in the entire load region,
It is distributed to each cylinder along the flow of air, stable combustion is obtained, and effects such as suppression of unburned component discharge, smooth operation, and improvement in output performance are achieved. At the same time, the overall height of the engine can be lowered, which is extremely advantageous when mounted on a vehicle.

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, the intake system for the V-type multi-cylinder engine according to the present invention uses the intake manifold in which the collecting portion is arranged in the center and the branches are radially extended, and the fuel is tangentially horizontally above the collecting portion. The ring-shaped swirl chambers are arranged to be connected to each other, and the collecting part and the swirl chambers are communicated with each other by a cylindrical slit, and the opening degree of the slit is controlled by a piston valve that responds to negative intake pressure. With this, the overall height of the engine can be set low, the atomization and vaporization of fuel in all operating regions can be promoted, the fuel distribution can be evenly distributed to each cylinder, and the effect of improving engine output performance can be obtained. is there.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view of a V-type 6-cylinder engine intake system showing an embodiment of the present invention, FIG. 2 is a plan view taken along the line A--A in FIG. 1, and FIG. A front view, FIG. 4 is a vertical cross-sectional front view of a main part showing another embodiment, and FIG. 5 is a partial vertical front view of a V-type multi-cylinder engine having a conventional intake system. 7 ... intake port, 8 ... intake manifold, 10 ... collecting part, 11 ... manifold, 12 ... swirl chamber, 13 ... slit, 14 ... piston valve, 15, 24 ... spring, 2
0 ... Intake passage, 21 ... Fuel supply device.

Claims (1)

(57) [Claims] 1. A V-type multi-cylinder engine having an intake manifold in which a collecting portion is located at a central portion of a V-shaped space, and the downstream ends of the planches extending in four directions from the collecting portion are connected to respective intake ports. A ring-shaped swirl chamber in which the intake passage is introduced horizontally in the tangential direction is superposed on the gathering portion, and communicates with the gathering portion through a cylindrical slit opened in the lower part of the circumference of the swirling chamber and swirls By inserting a piston valve that can slide up and down on the inner circumference, the opening of the slit can be changed,
An intake device for a V-type multi-cylinder engine, wherein a spring is elastically mounted on the piston valve to impart upward biasing force for increasing the slit opening.