JPS6235887Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an air-fuel mixture distribution device that evenly distributes an air-fuel mixture to each cylinder of a multi-cylinder engine. This invention relates to improving the distribution of air-fuel mixture.

Conventionally, as a mixture distribution device for this type of engine, as disclosed in, for example, Japanese Utility Model Application No. 53-150315, etc., a mixture distributing device has been used, for example, in the bottom part of the inner wall of the intake manifold directly below the carburetor that forms the mixture, which is perpendicular to the cylinder row direction. It has been proposed that a distribution wall is provided protruding from the center line of the intake manifold, and the distribution wall equalizes the distribution of fuel to each cylinder group during engine operation.

By the way, in such an engine, when taking out the intake negative pressure as a drive source for various auxiliary equipment from the intake passage directly downstream of the throttle valve of the carburetor through the VC port, it is necessary to ensure the accuracy of the manufacturing process or negative pressure. From this point of view, the above VC port is preferentially opened on the center line of the intake manifold perpendicular to the cylinder row direction, and the idle port for supplying fuel downstream of the throttle valve during low speed operation is set as above.
In order to avoid interference with the VC port, the intake manifold is opened offset to the left or right with respect to the center line of the intake manifold.

However, in the above proposed example, the distribution wall that distributes the air-fuel mixture is formed at the bottom of the inner wall of the intake manifold on the intake manifold center line perpendicular to the cylinder row direction, so the amount of fuel sucked out from the idle port is small. , and the negative pressure at that time is also large, it is difficult to stably and evenly distribute the fuel from the offset idle port to each cylinder on the left and right, and as a result, the idle stability of the engine is affected. There was a problem of being blocked.

Therefore, the present invention was developed in view of this point, and the distribution wall for air-fuel mixture distribution as in the above-mentioned proposal example is used to distribute the fuel sucked out from the idle port offset from the left-right center line of the intake manifold. The purpose of this is to improve idle stability by using it for distribution.

In order to achieve this object, the configuration of the present invention is such that in an engine in which the idle port of the carburetor is offset from the center line of the intake manifold orthogonal to the cylinder row direction, the carburetor idle port is located approximately directly below the idle port. The inner wall of the intake manifold is provided with a distribution wall that protrudes in a direction substantially perpendicular to the cylinder row direction and distributes fuel sucked out from the idle port to each cylinder.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

1 to 3, 1 is a four-cylinder engine having four cylinders 2, 2, etc. arranged in series in the left-right direction, and 3 is an intake passage 4 that supplies intake air to each cylinder 2 of the engine 1. The intake manifold 3 has a collecting pipe part 3a which is open upward and has a figure 8 cross section, and is branched symmetrically from the lower end of the collecting pipe part 3a to form a part of the engine 1. It consists of four branch pipe parts 3b, 3b, . , 2).

As shown in FIG.
is attached, and the carburetor 5 includes a primary intake passage 4a having a primary throttle valve 6 therein;
A secondary intake passage 4b having a secondary throttle valve 7 that opens when the load is high is provided in parallel.
When the primary throttle valve 6 is closed (when the secondary throttle valve 7 is closed), fuel is injected directly downstream of the passage wall of the upper primary intake passage 4a to operate the engine 1 at low speed. A slow port 8 and an idle port 9 are opened, and the idle port 9 (slow port 8) is located at a position above the left-right center line l perpendicular to the cylinder row direction of the intake manifold 3 on the passage wall of the primary intake passage 4a. In order to avoid interference with a VC port (not shown) opened in the figure, the intake manifold 3 is provided offset to one side (left side in the figure) with respect to the left-right center line l of the intake manifold 3.

Further, the collecting pipe portion 3 of the intake manifold 3
The idle port 9 of the carburetor 5 is located on the inner wall surface of a.
A distribution wall 10 that protrudes in a direction perpendicular to the cylinder row direction of the engine 1 (a direction along the left-right center line l of the intake manifold 3) is integrally formed at a portion substantially directly below the idle port 9. It is configured so that the sucked fuel is distributed to the left and right cylinders 2, 2, . . . by the distribution wall 10. In FIG. 2, reference numeral 11 is an adjusting screw that changes the opening area of the idle port 9 to adjust the ratio of the amounts of fuel discharged from the idle port 9 and the slow port 8, respectively.

Here, to illustrate preferred examples of the dimensions, shape, etc. of the distribution wall 10, the distribution wall 10 is
If the primary side intake passage 4a is made to protrude beyond the center O part of the primary side intake passage 4a toward the secondary side intake passage 4b, the distribution of main fuel from the carburetor 5 will be greatly affected. It is preferable to make it protrude so that it does not.

Furthermore, the longer the length of the distribution wall 10 in the vertical direction is, the better the distribution performance of the wall flow of fuel from the idle port 9 is.

Furthermore, if we consider the difference in the length of the intake passages 4, 4, ... from the idle port 9 to the left and right cylinders 2, 2, ... and the wall flow of fuel from the idle port 9, the distribution Rather than arranging the wall 10 exactly at a location directly below the idle port 9,
As shown in FIG. 3, it is preferable to slightly shift the idle port 9 toward the offset side with respect to the left-right center line l of the intake manifold 3, from the viewpoint of improving fuel distribution.

Therefore, in the embodiment described above, the distribution wall 10 is provided protruding from the inner wall surface of the collecting pipe portion 3a of the intake manifold 3 at a portion corresponding to approximately directly below the idle port 9 of the carburetor 5. Port 9 is on the left and right center line l of the intake manifold 3
Even if the cylinders are offset from each other, the fuel sucked out from the idle port 9 during low speed operation of the engine 1 is evenly distributed to the left and right cylinders 2, 2, . . . by the distribution wall 10. In particular, immediately after the fuel is sucked out, the collecting pipe portion 3a
The distribution function for the wall flow that flows down the inner wall surface is enhanced. As a result, the concentration of the air-fuel mixture supplied into each cylinder 2 of the engine 1 becomes uniform, and the idle stability of the engine 1 can be improved.

Further, since the protruding dimension of the distribution wall 10 is short and its proportion to the entire intake passage 4 in the collecting pipe portion 3a is extremely small, the distribution wall 10 prevents the main fuel from being mixed from the carburetor 5. The air distribution performance is not hindered, and therefore the drivability of the engine 1 during normal operation can be stably ensured.

Incidentally, in the above embodiment, a case where the present invention is applied to a four-cylinder engine 1 has been described, but it goes without saying that the present invention can also be applied to other multi-cylinder engines.

As explained above, according to the present invention, in a multi-cylinder engine in which the idle port of the carburetor is provided offset from the center line of the intake manifold orthogonal to the cylinder row direction, the intake port located approximately directly below the idle port is provided. By protruding a distribution wall on the manifold's inner wall to distribute slow fuel from the idle port to each cylinder, fuel from the idle port is evenly distributed and supplied to each cylinder when the engine is running at low speed, so the engine speed is improved. This can improve idle stability.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall plan view of the intake manifold, FIG. 2 is an enlarged longitudinal cross-sectional view of the same main part, and FIG. 3 is a plan view of the main part. 1...Engine, 2...Cylinder, 3...Intake manifold, 5...Carburetor, 9...Idle port, 10...Distribution wall.

Claims (1)

[Scope of utility model registration request] In an engine in which the idle port of the carburetor is offset from the center line of the intake manifold, which is perpendicular to the direction of the cylinder rows, there is a valve on the inner wall of the intake manifold that is located approximately directly below the idle port in a direction that is approximately perpendicular to the direction of the cylinder rows. A mixture distribution device for an engine, characterized in that a distribution wall is provided that protrudes from the side and distributes fuel sucked out from an idle port to each cylinder.