JPH07117009B2 - Intake device for in-line 4-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Purpose of the Invention (1) Field of Industrial Application The present invention relates to first, second, third and fourth cylinders arranged in series at equal intervals in series. An intake manifold connected to the intake ports has a substantially Y-shaped first intake portion connected to the intake ports of the first and second cylinders and a substantially Y-shaped second intake portion connected to the intake ports of the third and fourth cylinders. The present invention relates to an intake device for a special row four-cylinder internal combustion engine, which is configured to have an intake section, and the first and second intake sections are connected to a pair of carburetors forming a dual carburetor.

(2) Related Art Conventionally, in such an intake device, a pair of carburetors of a dual carburetor are arranged so as to correspond to a midpoint between the first and second cylinders and a midpoint between the third and fourth cylinders. It is common to do.

(3) Problems to be Solved by the Invention By the way, as described above, if the respective carburetors are arranged corresponding to the respective midpoints between the first and second cylinders and between the third and fourth cylinders, Since the width of the dual vaporizer along the cylinder arrangement direction becomes large, there is a demand to reduce the width of the dual vaporizer by arranging the vaporizers on the sides close to each other. In this case, in the intake manifold, the first and second
The intake pipe portions corresponding to the second and third cylinders of the intake portion are closer to the intake passage axis of each carburetor. However, when the fuel atomization at low temperature and low speed is relatively poor, the fuel flows in each carburetor near the intake passage axis, so that the cylinders near the intake passage axis of each carburetor, that is, the second and the second cylinders A rich mixture will be supplied to the three cylinders.

Therefore, for example, as disclosed in Japanese Utility Model Laid-Open No. 60-6873, when the corresponding intake pipe portions corresponding to the second and third cylinders of the first and second intake portions are connected to each other by a balance tube, low temperature At low rotation speed, for example, air containing almost no fuel flows from the second intake section through the balance tube into the rich mixture flowing in the intake pipe section corresponding to the second cylinder of the first intake section. The air-fuel ratio of the air-fuel mixture supplied to the cylinder can be maintained appropriately. However, the balance tube disclosed in the above-mentioned publication is formed in a straight tube shape, and the air flowing from the balance tube disturbs the flow of the air-fuel mixture flowing through the intake section, which increases the intake resistance.

In view of the above circumstances, a first object of the present invention is to make the width of a double vaporizer relatively small, and to keep the intake resistance small, while maintaining an appropriate air-fuel ratio at low temperature and low rotation. Another object of the present invention is to provide an intake device for an in-line four-cylinder internal combustion engine.

By the way, when the secondary air is supplied to the intake manifold, it is necessary to supply the secondary air evenly to the intake ports of the respective cylinders. However, the shape of the pipeline for supplying the secondary air and It is difficult to select the pipe diameter, and if the pipe line is provided separately from the intake manifold, additional work will be required to connect the pipe line to the intake manifold, resulting in higher cost and space disadvantage. .

Therefore, a second object of the present invention is to achieve a structure for supplying secondary air evenly to each cylinder after achieving the first object. It is an object of the present invention to provide an intake system for an in-line four-cylinder internal combustion engine that is advantageously constructed.

In addition, a gas containing fuel such as blow-by gas blown out from the combustion chamber or vaporized gas released from a canister may be supplied to the intake manifold, and in this case as well as the above-mentioned secondary air, the gas is supplied to each cylinder. It is necessary to evenly supply the gas, and at that time, the structure for supplying the gas can be easily and space-wise configured while reducing the cost as in the case of the secondary air. desired.

A third object of the present invention is, in addition to achieving the first object, a structure for evenly supplying a gas containing a fuel to each cylinder, which is easy and space-saving while achieving cost reduction. It is an object of the present invention to provide an intake system for an in-line four-cylinder internal combustion engine that is advantageously constructed.

B. Structure of the Invention (1) Means for Solving the Problems According to the first invention, the pair of carburetors have their intake passage axes at the midpoint between the first and second cylinders and the third carburetor. And a portion of the first intake portion corresponding to the second cylinder and a portion of the second intake portion corresponding to the third cylinder are arranged to be closer to each other than the midpoint between the fourth and fourth cylinders. It is inflated to the continuous carburetor side and connected by an arc-shaped balance tube integrated with the intake manifold.

According to the second invention, in addition to the configuration of the first invention, a secondary air supply pipe is connected to the balance tube.

Furthermore, according to the third aspect of the present invention, in addition to the configuration of the first aspect of the invention, the first and second intake portions are connected upstream of the connection portion of the balance tube by a communication pipe integral with the intake manifold. A gas supply pipe for mixing gas containing fuel into intake air is connected to the communication pipe.

(2) Action According to the configuration of the first aspect of the invention, the width of the dual vaporizer can be reduced, and moreover, the first and second intake portions communicate with each other via the balance tube. By reducing the width of the dual carburetor, the mixture supplied to the second and third cylinders is prevented from becoming rich at low temperature and low rotation, and the balance tube is expanded to the dual carburetor side. By forming the arc shape, it is possible to prevent the air-fuel mixture from being disturbed and suppress an increase in intake resistance.

Further, according to the configuration of the second invention, in addition to achieving the effect of the first invention, it is not necessary to provide a pipe line for supplying secondary air in addition to the intake manifold, thereby reducing the cost. At the same time, the structure is simplified, and space is also advantageous.

Further, according to the structure of the third aspect of the invention, in addition to achieving the effect of the first aspect of the invention, by providing a communication pipe integral with the intake manifold, it is possible to reduce the uniform supply of gas including fuel to each cylinder. This can be achieved at a cost and with a simple structure, and it is advantageous in terms of space.

(3) Example Hereinafter, an example of the present invention will be described with reference to the drawings.
First, referring to FIG. 1 showing an embodiment of the first invention, the engine body 1 has first, second, third and fourth cylinders C1, C2, C3, C.
4 are arranged at equal intervals in this order and in series. In order to supply the air-fuel mixture to these cylinders C1 to C4, a side draft dual carburetor 2 is connected to the engine body 1 via an intake manifold 3.

The intake manifold 3 includes a first intake portion 4 for supplying the air-fuel mixture to the first and second cylinders C1, C2, and third and fourth
It has a second intake section 5 for supplying the air-fuel mixture to the cylinders C3, C4. The first intake portion 4 has an intake pipe portion 4a that communicates with the intake port P1 of the first cylinder C1 and an intake pipe portion 4b that communicates with the intake port P2 of the second cylinder C2. 2 The intake part 5 is an intake pipe part 5a communicating with the intake port P3 of the third cylinder C3 and an intake pipe part communicating with the intake port P4 of the fourth cylinder C4.
5b and is formed in a substantially Y shape.

The dual carburetor 2 includes a carburetor 2a connected to the first intake section 4,
The carburetor 2b connected to the second intake section 5 is connected so as to interlock with each other. Moreover, these carburetors 2a, 2b have the first intake passage axis 6a, 6b in order to minimize the width of the dual carburetor 2 along the cylinder arrangement direction in the engine body 1.
And the midpoint between the second cylinder C1 and C2 and the third and fourth cylinders
The cylinders C3 and C4 are arranged so as to be closer to each other than the middle point. Therefore, the intake path axes 6a, 6b in the respective carburetors 2a, 2b are the intake pipe portions 4b, 5a corresponding to the second and third cylinders C2, C3 in the first and second intake portions 4,5 of the intake manifold 3. You will be leaning.

First and second intake parts 4,5 in the intake manifold 3
A balance tube 7 that integrally connects the intake pipe portions 4b and 5a is provided therebetween. Moreover, the balance tube 7 is bulged toward the dual carburetor 2 side, that is, formed in an arc shape with the engine body 1 side as the center, and at the joint portion between the balance tube 7 and the intake portions 4b, 5a. Are formed with arcuate chamfers 8 and 9, respectively.

Next, the operation of this embodiment will be described. The air-fuel mixture containing the fuel atomized in one vaporizer 2a of the dual vaporizer 2 is
The air-fuel mixture containing the fuel atomized by the other carburetor 2b is supplied to the first and second cylinders C1 and C2 during their intake strokes, respectively, and is supplied to the third and fourth cylinders C3 and C4 during their intake strokes. Each is supplied.

It is assumed that the intake stroke of the second cylinder C2 at low temperature and low speed is performed. At this time, the atomization of the fuel is not properly performed in the one carburetor 2a, and the fuel flows near the intake passage axis 6a. Therefore, the air-fuel mixture becomes rich in the intake pipe portion 4b which corresponds to the second cylinder C2 and is arranged closer to the intake passage axis 6a side. However, in the other carburetor C2, since the third and fourth cylinders C3, C4 are not in the intake stroke, the amount of circulating air is small, and therefore the fuel is hardly atomized. The air containing almost no fuel flows into the intake pipe portion 4b through the balance tube 7, and the rich air-fuel mixture from the carburetor 2a can be diluted with air to form an air-fuel mixture having an appropriate concentration.

Moreover, since the balance tube 7 is formed in an arc shape that bulges toward the dual carburetor 2, the air smoothly flows into the intake pipe portion 4b of the first intake portion 4, which is substantially Y-shaped. Therefore, it is possible to avoid the occurrence of turbulence in the air-fuel mixture as much as possible and suppress an increase in suction resistance. Further, since the chamfered portions 8 and 9 are provided at the joint portion of the balance tube 7 with the both intake portions 4 and 5, the suction resistance at these joint portions can be reduced.

Such an operation is performed by the second intake section 5 corresponding to the third cylinder C3.
The same applies to the intake pipe portion 5a of the above, and therefore, even though the vaporizers 2a and 2b are brought close to each other to reduce the width of the dual vaporizer 2, the low temperature in the second and third cylinders C2 and C3, The air-fuel mixture concentration can be appropriately maintained at low speed.

FIGS. 2 and 3 show an embodiment of the second invention, and the portions corresponding to the embodiment of FIG. 1 are designated by the same reference numerals.

A secondary air supply pipe 10 for supplying secondary air to the air-fuel mixture is connected to a substantially central upper portion of the balance tube 7 which is integral with the intake manifold 3 having a jacket 3a in the lower portion.

According to this structure, the secondary air supplied from the secondary air supply pipe 10 is supplied from the balance tube 7 to the intake pipe portions 4a, 4a.
cylinders C1 to C4 that can be supplied to b, 5a, 5b and are in the intake stroke
The secondary air is evenly distributed over the air.

Moreover, the balance tube 7 integrated with the intake manifold 3
Since the secondary air supply pipe 10 is connected to the above, the effect of the embodiment of FIG. 1 can be obtained, and in addition, in order to distribute the secondary air evenly to the cylinders C1 to C4, It is not necessary to provide a pipe line for supplying secondary air separately from the manifold 3, the structure can be simplified, and the man-hours for connecting the pipe lines are not required, and the cost can be reduced. In addition, a space for providing the pipe is not necessary.

FIG. 4 and FIG. 5 show an embodiment of the third invention, and the portions corresponding to the embodiment are designated by the same reference numerals.

On the upstream side of the balance tube 7 of the intake manifold 3, the first and second intake portions 4 and 5 are connected to each other by a communication pipe 11 integrated with the intake manifold 3, and the communication pipe 11 has
A gas supply pipe 12 for supplying a gas containing fuel such as blow-by gas or vaporized gas from a canister is connected.

By doing so, in addition to the effect of the embodiment of FIG. 1, the gas containing fuel can be evenly distributed to the cylinders C1 to C4 by the communication pipe 11, and the communication pipe 11 causes the intake manifold 3 to operate. Since it is formed integrally with, it is advantageous in terms of man-hours and cost, and also in terms of space.

C. Effect of the Invention As described above, according to the first invention, in the pair of carburetors, the intake passage axes of the carburetors are at the midpoint between the first and second cylinders and the midpoint between the third and fourth cylinders. The portions corresponding to the second cylinder in the first intake portion and the portion corresponding to the third cylinder in the second intake portion swell toward the dual carburetor side. Since it is connected by an arc-shaped balance tube that is integral with the intake manifold, the width of the dual carburetor is reduced, and the concentration of the air-fuel mixture supplied to the second and third cylinders at low temperatures and low rotation is properly adjusted. It becomes possible to keep the air-fuel mixture, and the balance tube can be made into an arc shape to prevent the mixture from being disturbed and suppress the increase of the intake tendency.

According to the second invention, in addition to the configuration of the first invention, since the secondary air supply pipe is connected to the balance tube, the effect of the first invention is exerted and the secondary air is supplied. In order to supply air, it is not necessary to provide a pipe line separately from the intake manifold, the structure is simplified and cost is reduced, and the man-hours for connecting the pipe lines are unnecessary, and further, the pipe line is unnecessary. This is advantageous in terms of space.

According to a third aspect of the invention, in addition to the configuration of the first aspect of the invention, the first and second intake portions are connected to the intake manifold on the upstream side of the connection portion of the balance tube by a communication pipe integral with the intake manifold. Since a gas supply pipe for mixing gas containing fuel into intake air is connected to the pipe, a structure for evenly distributing gas containing fuel to each cylinder in addition to the effect of the first aspect of the invention is obtained. In addition, since the communication pipe is integrated with the intake manifold, the man-hours for connection are not required, the cost is reduced, and the space is advantageous.

[Brief description of drawings]

FIG. 1 is a plan view of an embodiment of the first invention, FIGS. 2 and 3 show an embodiment of the second invention, and FIG.
FIG. 3 is a plan view, FIG. 3 is a sectional view taken along line III-III in FIG. 2, and FIG.
FIGS. 5 and 5 show an embodiment of the third invention. FIG. 4 is a plan view and FIG. 5 is a sectional view taken along the line VV of FIG. 2 ... Dual vaporizer, 2a, 2b ... Vaporizer, 3 ... Intake manifold, 4 ... First intake part, 5 ... Second intake part, 6
a, 6b …… Intake passage axis, 7 …… Balance tube, 8,9…
… Chamfer, 10 …… Secondary air supply pipe, 11 …… Communication pipe, 12…
… Gas supply pipe C1 to C4 …… Cylinder, P1 to P4 …… Intake port

Claims (4)

[Claims] 1. An intake manifold connected to intake ports of first, second, third, and fourth cylinders arranged in series at equal intervals in sequence, wherein intake manifolds of first and second cylinders are provided. And a third Y-shaped first intake portion connected to the
It has a substantially Y-shaped second intake part connected to each intake port of the cylinder, and a pair of carburetors forming a dual carburetor are connected to the first and second intake parts. In an intake system for an in-line four-cylinder internal combustion engine, the pair of carburetors have their intake passage axes located at a midpoint between the first and second cylinders and a third carburetor.
And a portion of the first intake portion corresponding to the second cylinder and a portion of the second intake portion corresponding to the third cylinder are arranged to be closer to each other than the midpoint between the fourth and fourth cylinders. Series 4 characterized by being connected to the intake manifold by an arc-shaped balance tube that expands to the side of the continuous carburetor
Intake device for a cylinder internal combustion engine. 2. The series according to claim 1, wherein an arcuate chamfered portion is formed at a joint portion of the balance tube with the first and second intake portions. Intake device for 4-cylinder internal combustion engine. 3. An intake manifold connected to each intake port of first, second, third and fourth cylinders arranged in series at equal intervals, wherein the intake ports of the first and second cylinders are connected to each other. And a third Y-shaped first intake portion connected to the
It has a substantially Y-shaped second intake part connected to each intake port of the cylinder, and a pair of carburetors forming a dual carburetor are connected to the first and second intake parts. In an intake system for an in-line four-cylinder internal combustion engine, the pair of carburetors have their intake passage axes located at a midpoint between the first and second cylinders and a third carburetor.
And a portion of the first intake portion corresponding to the second cylinder and a portion of the second intake portion corresponding to the third cylinder are arranged to be closer to each other than the midpoint between the fourth and fourth cylinders. An intake device for an in-line four-cylinder internal combustion engine, wherein the intake pipe is expanded to the continuous carburetor side and is connected to an intake manifold by an arc-shaped balance tube, and a secondary air supply pipe is connected to the balance tube. 4. An intake manifold connected to intake ports of first, second, third and fourth cylinders, which are arranged in series at equal intervals in sequence, wherein intake manifolds of first and second cylinders are provided. And a third Y-shaped first intake portion connected to the
It has a substantially Y-shaped second intake part connected to each intake port of the cylinder, and a pair of carburetors forming a dual carburetor are connected to the first and second intake parts. In an intake system for an in-line four-cylinder internal combustion engine, the pair of carburetors have their intake passage axes located at a midpoint between the first and second cylinders and a third carburetor.
And a portion of the first intake portion corresponding to the second cylinder and a portion of the second intake portion corresponding to the third cylinder are arranged to be closer to each other than the midpoint between the fourth and fourth cylinders. The arc-shaped balance tube that bulges toward the continuous carburetor side and is integrated with the intake manifold is connected, and the first and second intake parts are connected upstream of the connection part of the balance tube by a communication pipe integrated with the intake manifold. An intake device for an in-line four-cylinder internal combustion engine, wherein a gas supply pipe for mixing gas containing fuel into intake air is connected to the communication pipe.