JP2839657B2 - Intake manifold for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an intake manifold that distributes intake air from an air cleaner to each cylinder.

[Conventional technology]

In recent internal combustion engines, a chamber arranged to extend in the direction of the cylinder row, and an intake port in each cylinder,
An intake manifold is applied in which each cylinder is connected via a branch intake pipe independent of each other to thereby obtain an inertia supercharging effect.

Each of the divided intake lines in this type of intake manifold must be relatively long in order to obtain a predetermined inertia supercharging effect.
For example, as described in Japanese Utility Model Laid-Open Publication No. 61-75665 and the like, it once protrudes downward from a chamber arranged so as to extend in the direction of the cylinder row to the side of the internal combustion engine, and is appropriately horizontally oriented with a radius of curvature. After connecting to the intake port opened on the side surface of the cylinder head, in other words, a portion of each of the branch intake pipes connected to the intake port is connected to the laterally extending pipe portion that extends substantially linearly. Is connected to a riser pipe portion extending substantially linearly, and a portion between the riser pipe portions is formed as a curved pipe portion curved upward, so that each of the branch intake pipes is substantially L when viewed from the crankshaft direction of the internal combustion engine. It is made to curve in a letter shape.

[Problems to be solved by the invention]

However, when each branch intake pipe is curved in a substantially L-shape, the resistance of the intake flow in each branch intake pipe becomes
Of the respective branch intake pipes, proportional to the bending angle in the bending pipe portion, inversely proportional to the bending radius in the bending pipe portion, large when the bending angle is large and when the bending radius is small,
While small when the bend angle is small and large when the bend radius is large, each branch intake line requires a predetermined length dimension to achieve inertial supercharging.

Therefore, in order to reduce the size of the intake manifold and increase the rigidity, the chamber in the intake manifold must be configured to be close to the internal combustion engine. Since the bending angle in the curved pipe portion of the intake pipe becomes larger than the right angle and the bending radius in the curved pipe portion also becomes smaller, the flow resistance of the intake air increases, and the output is reduced. was there.

The present invention provides a configuration in which, when the chamber is brought close to the internal combustion engine in order to reduce the size of the intake manifold, the intake flow resistance in each branch intake pipe can be prevented from increasing by the shape of the curved portion. It is a technical issue.

[Means for solving the problem]

In order to achieve this technical object, the present invention provides a method of connecting a chamber extending in the direction of a cylinder row and an intake port of each cylinder with a branch intake pipe independent of each cylinder. In the branch intake pipe, a portion connected to the intake port is connected to a substantially straight laterally extending pipe portion, a portion connected to the chamber is connected to a substantially straight rising pipe portion, and a portion therebetween is upwardly bent at a right angle. In the intake manifold constituted by a curved pipe section curved at a large angle, the curved pipe section in each of the branch intake pipes is connected to an upstream curved pipe section connected to a rising pipe section to a chamber, and a lateral pipe to an intake port. And a downstream curved tube section connected to the section,
The radius of curvature of the downstream curved tube is made larger than the radius of curvature of the upstream curved tube. "

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, reference numeral 1 denotes a first cylinder A1, a second cylinder A2, and a third cylinder.
4 shows a four-cylinder internal combustion engine having an A3 and a fourth cylinder A4, and a longitudinal side surface 2a of a cylinder head 2 of the internal combustion engine 1 includes:
The intake ports 3, 4, 5, and 6 in each of the cylinders A1, A2, A3, and A4 are open.

Reference numeral 7 denotes an inertia-supercharged intake manifold for the internal combustion engine 1, and the intake manifold 7 is one of the chambers 8 arranged to extend in the direction of a cylinder row beside the internal combustion engine 1. 8 and the respective intake ports 3,
Four branch intake lines that connect separately between 4, 5, and 6
The chamber 8 is located at a position close to the internal combustion engine 1 while each of the branch intake pipes
9, 10, 11, and 12 are curved in a substantially L-shape in a side view.

In other words, each of the branch intake pipes 9, 10, 11, 12 is connected to a laterally oriented pipe portion D having a substantially linear portion connected to the intake ports 3, 4, 5, 6 and a lower surface of the chamber 9. And a rising pipe section B connecting the rising pipe section C and the horizontal pipe section D, and a bending angle in the bending pipe section B. Are configured at an angle greater than a right angle.

The curved pipe section B in each of the branch intake pipes 9, 10, 11, 12 is connected to an upstream curved pipe section B1 connected to a rising pipe section C to the chamber 8, and each of the intake ports 3, 4, 5,. 6 comprising a downstream curved tube portion B2 connected to the transverse tube portion D to 6,
The configuration is such that the bending radius R2 of the downstream bending portion B2 is larger than the bending radius R1 of the upstream bending tube portion B1.

The rising pipe section C in each of the branch intake pipes 9, 10, 11, 12 gradually increases in cross-sectional area toward the chamber 8, in other words, gradually increases in cross-sectional area toward the curved pipe section B. It is configured to decrease.

Each branch intake pipe 9, 10, 11, 12 in the inertia supercharged intake manifold 7 needs a predetermined length dimension, so that the chamber 8 is placed close to the internal combustion engine 1,
In order to secure a predetermined length dimension in each of the branch intake pipes 9, 10, 11, and 12, the bending angle of each of the branch intake pipes 9, 10, 11, and 12 in the curved pipe portion B is made larger than a right angle. At the same time, the bending radius R in the bending pipe portion B must be relatively small as shown by a two-dot chain line E in FIG. 2 and shown in FIG. , 10, 11, and 12, the flow resistance of the intake air increases, and the effect of inertia supercharging decreases.

By the way, the intake flow resistance in the curved pipe portion B of each of the branch intake pipes 9, 10, 11, 12 increases in proportion to the flow velocity of the intake air in the pipes, is proportional to the bending angle, and has a bending radius. Is inversely proportional to each of the branch intake pipes 9,
The flow of the intake air in 10, 11, 12 can be regarded as a flow in which the compressible gas flows while adiabatically expanding in the direction of lower pressure, and the flow of the intake air in each branch intake pipe 9, 10, 11, 12 The flow rate of the intake air is the slowest in the part near the chamber 8,
From this part, the air is gradually accelerated by adiabatic expansion toward each of the intake ports 3, 4, 5, and 6, so that the intake flow resistance in the downstream curved pipe portion of the curved pipe portion is higher due to the flow velocity of the intake air. In addition, there is a tendency that the intake flow resistance in the upstream curved pipe portion of the curved portion is larger than the intake flow resistance.

The inventor pays attention to this point, and as described above, connects the curved pipe section B in each of the branch intake pipes 9, 10, 11, 12 to the upstream curved pipe connecting the rising pipe section C to the chamber 8. B1 and a downstream curved pipe section B2 connected to a lateral pipe section D to each of the intake ports 3, 4, 5, and 6, and a bending radius R2 of the downstream curved pipe section B2 is defined by the upstream curved section. It was decided to make it larger than the radius of the tube section B1.

In other words, the flow velocity of the intake air in the downstream curved pipe section B2 of the curved pipe sections B of the branch intake pipes 9, 10, 11, 12 is the intake flow rate in the upstream curved pipe section B1 of the curved pipe section B. Is lower than the flow velocity of the downstream curved pipe section B2 where the intake flow velocity is high.
By setting the large curvature radius R2 at, it is possible to reliably prevent the intake flow resistance from increasing.

〔The invention's effect〕

Therefore, according to the present invention, the flow resistance of intake air in each branch intake pipe can be reduced in a state where a predetermined flow size is secured in each branch intake pipe, so that an inertia supercharged intake manifold is provided. This has the effect of reliably preventing a reduction in output due to intake flow resistance without increasing the size.

[Brief description of the drawings]

1 and 2 show an embodiment of the present invention. FIG. 1 is a plan view, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG.
It is a figure which shows the conventional thing in the sectional view of the same location as a figure. 1 ... internal combustion engine, A1, A2, A3, A4 ... cylinder, 2 ... cylinder head, 3, 4, 5, 6 ... intake port, 7 ... intake manifold, 8 ... chamber, 9, 10, 11, 12 ... branch intake pipe, B ... curved pipe section, B1 ... upstream curved pipe section, B2 ... downstream curved pipe section, C ... rising section, D ... sideways section.

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁶ , DB name) F02M 35/104 F02B 27/00

Claims (1)

(57) [Claims] An independent branch intake pipe is connected to each of the cylinders between a chamber extending in the direction of the cylinder row and an intake port of each cylinder. A curved tube portion curved at an angle larger than a right angle, with a portion connected to the port being a substantially straight horizontal tube portion, a portion connected to the chamber being a substantially straight riser tube portion, and a portion therebetween being upwardly curved at an angle larger than a right angle. In the intake manifold, the curved pipe section in each of the branch intake pipes is connected to an upstream curved pipe section connected to a rising pipe section to a chamber, and a downstream curved pipe section connected to a horizontal pipe section to an intake port. Wherein the curvature radius of the downstream curved tube portion is larger than the curvature radius of the upstream curved tube portion.