JPH0882259A - Intake manifold for multiple cylinder engine - Google Patents

Abstract

PURPOSE: To supply an intake air also to a combustion chamber on the deep side of a multiple cylinder engine at the same speed as an inlet-side combustion chamber. CONSTITUTION: In an intake manifold for multiple cylinder engine having a cylindrical intake air distributing passage 31 extended in the juxtaposing direction of a four cylinder engine, and four branched pipes 32a, 32b, 32c, 32d successively derived in the longitudinal direction of the cylindrical intake air distributing passage 31, since the cylindrical intake air distributing passage 31 is formed into a tapered conical form extending from at least the first branched pipe 23a arrangement position on the inlet side to the deepest branched pipe 32d arrangement position, the speed of the intake air flowing into a combustion chamber on the deep side of the multiple cylinder engine can be set to about the same degree as the inflow speed of an inlet-side combustion chamber, and the combustion in the deep-side combustion chamber can be stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake manifold used in a gas engine, a gasoline engine and the like, and more particularly to an intake manifold used in a multi-cylinder engine.

[0002]

2. Description of the Related Art An intake manifold is an intake pipe having a branch pipe for distributing an air-fuel mixture that has passed through an air cleaner, a carburetor (or a mixer), etc., to each cylinder of a multi-cylinder engine, and various shapes have been conventionally proposed. Has been done. The function required of the intake manifold is high filling efficiency of the air-fuel mixture in the entire engine rotation range. Distribute the air-fuel mixture evenly to each cylinder. There are no sudden changes in cross-sectional area or sharp bends. As the length and shape from the carburetor to the cylinder are the same in each branch pipe, the air-fuel mixture distributed to each cylinder can be made more uniform. Therefore, for example, in the case of a four-cylinder engine, it is ideal that the carburetor is arranged in the center of the engine and that the air-fuel mixture is supplied to the left and right two cylinders in the same intake pipe shape.

However, when it is difficult to dispose the carburetor at the center of the engine because of the structure, as shown in FIG.
The direction in which the cylinders of the cylinder engine 55 are arranged side by side
(Shown in FIG. 4) is provided, and the branch pipes 53, 54, 55, 56 that communicate with the intake ports of the cylinder heads are led out from the mixture distribution passage 52. . In this case, the air-fuel mixture distribution passage 52 is a cylindrical intake passage having a cross-sectional area corresponding to the maximum flow rate, and the branch pipe 5 communicating with each intake port at equal intervals in the longitudinal direction.
3, 54, 55, 56 are branched. Further, the inner diameter of the air-fuel mixture distribution passage 52 is formed so as to be constant from the position where the first branch pipe 53 on the inlet side is arranged to the position where the innermost branch pipe 56 is arranged. In FIG. 6, reference numeral 50 indicates an intake manifold and reference numeral 55 indicates an exhaust manifold.

[0004]

However, with the above-mentioned conventional configuration, the cylinders 55, 54 on the back side are compared to the cylinders 53, 54 closer to the inlet side of the intake manifold 50.
The intake passage for the intake to 56 becomes long, so the intake resistance increases and the inflow speed of each cylinder into the cylinder decreases. When the flow velocity decreases, it becomes difficult to evenly distribute the air-fuel mixture in the combustion chamber, and the air-fuel mixture is unevenly distributed in the combustion chamber. As a result, problems such as poor ignition and increased NOx occur.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and intake air of a multi-cylinder engine capable of supplying intake air to a combustion chamber on the back side of the multi-cylinder engine at the same speed as the combustion chamber on the inlet side. Intended to provide a manifold.

[0006]

An intake manifold according to a first aspect of the present invention for achieving the above object is, for example, a tubular shape extending in a direction in which a plurality of cylinders are arranged in parallel, as described with reference to FIGS. 1 to 5. An intake air distribution passage 31 is provided, and a number of branch pipes 32 corresponding to the number of cylinders are sequentially led out in the longitudinal direction of the cylindrical intake distribution passage 31.
In the intake manifold of a multi-cylinder engine that communicates with the intake port 10, the cylindrical intake distribution passage 31 has a tapered shape from at least the first branch pipe 32a disposed position on the inlet side to the innermost branch pipe 32d disposed position. It is characterized by being formed in. In the case of the tapered shape, it is preferable that the cross-sectional area of the cylindrical intake distribution passage 31 is gradually reduced to be reduced. Examples of the shape of such a cylindrical intake distribution passage 31 include a conical shape and a substantially pyramidal shape.

The cross-sectional area of the branch pipe 32 sequentially led out to the cylindrical intake distribution passage 31 can be gradually reduced from the first branch pipe 32a on the inlet side to the innermost branch pipe 32d. Further, each branch pipe 3 in the tubular intake distribution passage 31
In the lead-out part of No. 2, the cross-sectional area of the tubular intake distribution passage 31 and the cross-sectional area of each branch pipe 32 at the position where each branch pipe 32 is led out are made approximately the same, and The reduction rate of the cross-sectional area and the reduction rate of the cross-sectional area of each branch pipe 32 can be communicated to the intake port 10 at substantially the same rate.

[0008]

In the intake manifold according to the first aspect of the present invention, since the tubular intake distribution passage 31 is tapered toward the inner side, the velocity of the intake air flowing through the branch pipes 32c and 32d led out to the inner side is increased. The speed increases, and the speed of intake air flowing into the combustion chamber 13 corresponding to the branch pipes 32c and 32d increases. As a result, in the cylinder on the back side, a decrease in speed due to an increase in intake resistance due to a longer intake passage can be offset, and an inflow speed substantially equal to the inflow speed of the cylinder on the inlet side can be achieved. Therefore, even in the combustion chamber 13 communicating with the branch pipes 32c, 32d on the inner side, the branch pipes 32a, 3 on the inlet side are also provided.
Like the combustion chamber 13 communicating with 2b, intake air can be uniformly distributed in the combustion chamber, and combustion can be stabilized. Further, when the intake air is a mixture of gasoline or gas and the outside air, the difference between the mixture state of the gasoline or gas and the outside air in the combustion chamber 13 on the back side and the combustion chamber 13 on the inlet side should be reduced. As compared with the conventional configuration, ignition can be reliably performed by the spark plug in the cylinder on the back side, and NOx can be reduced.

Further, in the case of a gasoline engine, gasoline is not vaporized only by the carburetor, and the vaporization of gasoline is also assisted in the cylindrical intake distribution passage 31 and the branch pipe 32, so that the inflow speed to the intake port 10 is increased. By making them substantially uniform, the vaporized state of gasoline can also be made substantially uniform, and the combustion in the combustion chamber 13 on the back side can be stabilized. It should be noted that the cylindrical intake distribution passage 3 is smoothly and continuously formed.
By configuring so as to reduce the cross-sectional area of 1, it is possible to reduce the intake resistance in the cylindrical intake distribution passage 31 and prevent the occurrence of turbulence.

Further, the cross-sectional area of the branch pipe 32 that is sequentially drawn out into the cylindrical intake distribution passage 31 is gradually reduced from the first branch pipe 32a on the inlet side to the innermost branch pipe 32d, thereby forming a tapered shape. The intake pipe can be extended substantially to the vicinity of the intake port 10 of the cylinder head 4, and the reduction rate of the cross-sectional area can be moderated. Further, in the lead-out portion of each branch pipe 32 in the tubular intake distribution passage 31, the cross-sectional area of the tubular intake distribution passage 31 and the cross-sectional area of each branch pipe 32 at the position where each branch pipe 32 is led out are approximately the same. In addition, the reduction rate of the cross-sectional area in the tubular intake distribution passage 31 and the reduction rate of the cross-sectional area in each branch pipe 32 are communicated to the intake port 10 at substantially the same rate, so that the cross-sectional area is locally reduced. The intake resistance can be reduced without changing to.

[0011]

Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments. FIG. 5 is a schematic configuration diagram when the intake manifold of this embodiment is applied to a gas engine. In FIG. 5, the gas engine 1 has a cylinder block 3 integrally formed above a crankcase 2, and a cylinder head 4 and a head cover 5 are sequentially mounted and fixed on the upper surface of the cylinder block 3 to form an engine body. I am doing it. Inside the cylinder block 3, there is a cylinder 6 and a piston 7.
Is slidably inserted and the piston 7 is interlockingly connected to a crankshaft 9 via a connecting rod 8. An intake port 10 and an exhaust port 11 are formed in the cylinder head 4, and a branch pipe 32 of an intake manifold 30 according to this embodiment is connected to the intake port 10. Further, the cylinder head 4 is provided with a combustion chamber 13 into which the lean air-fuel mixture supplied from the intake port 10 enters. A mixer 22 that mixes the intake air from which dust has been removed by the air cleaner 21 with the gas is connected to the intake side inlet of the intake manifold 30 via an intake pipe 23.

FIG. 1 is a plan view showing an embodiment of the intake manifold of the present invention, FIG. 2 is a view taken along the line EE of FIG. 1, and FIG.
(A), (b) and (c) are lines AA and BB in FIG. 1, respectively.
Line, CC line enlarged sectional view, FIG. 4 is a DD line enlarged sectional view of FIG. The intake manifold 30 according to the present embodiment is
As shown in FIGS. 1 to 4, there is a cylindrical intake distribution passage 31 through which a mixture of intake air and gas passes, and this cylindrical intake distribution passage 31 has a large inner diameter on the inlet side 33 and a deep inner side. It has a tapered shape (conical shape) whose inner diameter gradually decreases as it goes. Referring to FIG. 3, D1>D2> D
It is 3. Further, branch pipes 32a, 32b, 32c, 32d are led out from the inlet side to the cylindrical intake distribution passage 31 at regular intervals, and each branch pipe 32 is connected to the intake port 1 of the cylinder head 4.
It communicates with 0. The cylindrical intake distribution passage 31 is inclined and fixed to the engine so that the inlet side has a long distance and the rear side has a short distance with respect to the surface of the intake port 10 of each engine. Therefore, the length of the branch pipe 32a on the inlet side of the cylindrical intake distribution passage 31 is longer than that of the branch pipe 32d on the inner side.

The sectional shape of the branch pipe 32 is as shown in FIG.
It has a rectangular shape with rounded corners, and its cross-sectional area is configured to gradually decrease from the connecting portion of the cylindrical intake distribution passage 31 as shown in FIG. 3, and each intake port 10 as shown in FIG.
At a predetermined position before being connected to the branch pipe 32 on the inlet side
Not limited to the a and the branch pipes 32d on the back side, they are configured to have a constant area. In addition, the cylindrical intake distribution passage 31 and each branch pipe 3
The connection portion with 2 is formed sufficiently smooth so that the intake resistance does not increase. As shown in FIG. 1, an intake manifold mounting flange 35 is provided near the inlet side of the intake manifold 30, and at the mounting peripheral portion of each branch pipe 32 corresponding to the intake port 10 of the cylinder head 4. Is also provided with a mounting flange 36.

The operation of the intake manifold having the above structure will be described. The intake valve (not shown in FIG. 5) of the intake port 10 is opened and the piston 7 is lowered,
The combustion chamber 13 and the intake port 10 have a negative pressure, and the air-fuel mixture in the cylindrical intake distribution passage 31 is sucked into the combustion chamber 13 through each branch pipe 32 and each intake port 10. Here, since the inner diameter of the cylindrical intake distribution passage 31 on the back side is tapered gradually smaller than the inner diameter on the inlet side, if the intake passages have the same length, the inner position The flow velocity in the cylindrical intake distribution passage 31 is faster than the flow velocity at the inlet side position. However, at the back position, there is an increase in the intake resistance due to the long intake passage, so the increase in the resistance offsets the increase in speed, and even in the combustion chamber corresponding to the back side, It is possible to achieve an inflow velocity that is approximately the same as the inflow velocity of the corresponding combustion chamber. Since the same inflow velocity can be obtained in the cylinder on the back side as in the cylinder on the inlet side, the fuel distribution is made uniform in the combustion chamber on the back side, lean combustion can be realized, and ignition is performed. It is possible to prevent mistakes and reduce NOx.

The present invention is not limited to the above embodiments, and various design changes can be made within the scope of the present invention. Hereinafter, such an embodiment will be described. (1) In the above-described embodiment, the gas engine 1 is taken as an example, but the present invention can be similarly applied to an engine using an air-fuel mixture such as a gasoline engine other than the gas engine. Even in a diesel engine that does not use air-fuel mixture, it is important to make the speed of the intake air flowing into each combustion chamber constant in order to improve the uniformity of the distribution of fuel injected from the fuel injection pump. Therefore, by applying the same method, it is possible to obtain the effect of stabilizing the combustion in the cylinder on the back side. (2) In the above embodiment, the cylindrical intake distribution passage 31 has a conical shape, but other shapes such as a substantially pyramidal shape can be adopted. Furthermore, the tubular intake air distribution passage 31 is not limited to a linear one, but a curved curved one can be adopted.

[0016]

As described above, according to the invention of claim 1,
By making the cylindrical intake distribution passage at least from the first branch pipe arranging position on the inlet side to the innermost branch pipe arranging position, the speed of the intake air flowing into each cylinder of the multi-cylinder engine is made substantially constant. Therefore, there is a unique effect that the combustion can be stabilized in the combustion chamber on the back side.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an intake manifold of the present invention.

FIG. 2 is a view taken along the line EE in FIG.

3 (a), (b), and (c) are AA of FIG. 1, respectively.
It is a line, a BB line, and a CC line expanded sectional view.

FIG. 4 is an enlarged cross-sectional view taken along line DD of FIG.

FIG. 5 is a schematic configuration diagram when the intake manifold of the present embodiment is applied to a gas engine.

FIG. 6 is a schematic diagram of an engine showing a configuration of a conventional intake manifold.

[Explanation of symbols]

4 ... Cylinder head, 10 ... Intake port, 31 ... Cylindrical intake distribution passage, 32a, 32b, 32c, 32d ... Branch pipe.

Claims (1)

[Claims] 1. A cylindrical intake distribution passage (31) extending in a direction in which a plurality of cylinders are arranged in parallel, and the cylindrical intake distribution passage (3).
1) In the longitudinal direction, the number of branch pipes (32
a, 32b, 32c, 32d) are sequentially derived, and each branch pipe (32a, 32b, 32c, 32d) is connected to the intake port (10) of each cylinder head (4) in an intake manifold of a multi-cylinder engine. , The tubular intake distribution passage (31) at least on the inlet side first branch pipe (3
2a) An intake manifold for a multi-cylinder engine, wherein the intake manifold is formed in a tapered shape from the disposition position to the disposition position of the innermost branch pipe (32d).