JP2524461Y2 - Intake manifold structure for multi-cylinder internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an intake manifold structure for a multi-cylinder internal combustion engine.

2. Description of the Related Art Conventionally, in an intake manifold structure of a multi-cylinder internal combustion engine, an air-fuel mixture supplied from a carburetor is configured to be branched and supplied to each cylinder via an intake manifold. The flow path is always constant at any of the low, medium and high speeds of the engine.

(Problems to be solved by the invention) However, since the air-fuel mixture is guided from the intake manifold to each cylinder in a branched state, especially when the air-fuel mixture flow rate is low, such as when the engine is operating at low to medium speeds, the air-fuel mixture flows to each cylinder. There was a drawback that uniform distribution could not be performed, and thus sufficient engine output could not be obtained.

(Means for Solving the Problems) In order to solve the problems of the prior art described above, the intake manifold structure of the multi-cylinder internal combustion engine of the present invention connects a dual carburetor having a primary passage and a secondary passage to an upstream side. In the intake manifold of a multi-cylinder internal combustion engine, a wall portion of a flow passage from a carburetor to an intake manifold protruding downward from the primary passage from a rising position where a cylindrical guide member having upper and lower ends opened into the primary passage is drawn into the primary passage. The guide member is connected to the upper end of a rod that can be moved up and down in parallel with the primary passage, and the lower end of the rod is provided outside the intake manifold. Connected to the diaphragm of the actuator, and in a negative pressure chamber in the actuator partitioned by the diaphragm in a no-load state. A compression coil spring for urging the guide member to the raised position via the rod is provided, and the negative pressure chamber is communicated with the intake manifold via a communication pipe.

(Operation) In the intake manifold structure of the multi-cylinder internal combustion engine of the present invention,
The air-fuel mixture supplied from the carburetor is always uniformly distributed to each cylinder in the low, medium, and high-speed engine operating regions by moving the guide member in accordance with the air-fuel mixture flow velocity. Therefore, a predetermined amount of fuel corresponding to the operating state is equally supplied to each cylinder.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a double-type carburetor having a primary passage 2 and a secondary passage 3 (only essential parts are shown), and an intake manifold 4 is connected to a downstream side thereof. Reference numeral 5 denotes a cylinder head of the engine, and the intake manifold 4 is branched and connected to each cylinder via the cylinder head 5.

Numeral 7 is a cylindrical guide member having upper and lower ends opened just inside the outlet of the primary passage 2 and provided in a wall 8 of a flow passage from the carburetor 1 to the intake manifold 4 in parallel with the primary passage 2. It is fixed to the upper end of a vertically movable rod 9. The guide member 7 is arranged on the upstream side of the branch portion to each cylinder, and the lower end is formed obliquely toward the wall portion 8.

A diaphragm type actuator 10 is attached to the outside of the intake manifold 4, and the lower end of the rod 9 is connected to a diaphragm 11 of the actuator 10. The inside of the actuator 10 is a diaphragm
A negative pressure chamber 12 and an atmospheric pressure chamber 13 are defined by 11, and the negative pressure chamber 12 communicates with the intake manifold 4 via a communication pipe 14. A compression coil spring 15 is mounted in the negative pressure chamber 12, and the compression coil spring 15 holds the rod 9 at a raised position shown by a broken line in FIG. 7 is also set so as to be completely drawn into the primary passage 2.

 Next, the operation of the above embodiment will be described.

First, when the engine is in a low-speed state, the air-fuel mixture is supplied only from the primary passage 2 of the carburetor 1. However, in a low-speed state, the negative pressure guided to the negative pressure chamber 12 of the actuator 10 through the communication pipe 14 is large. The coil spring 15 is pressed and contracted by the diaphragm 11, and the guide member 7 is lowered to a position substantially indicated by a solid line in the drawing.

In this state, the guide member 7 protrudes greatly downward from the primary passage 2, and the air-fuel mixture reaches the lower region of the intake manifold 4, so that the air-fuel mixture is uniformly distributed to each cylinder even if the flow velocity is low.

When the engine is in a medium speed state, the negative pressure guided into the negative pressure chamber 12 of the actuator 10 is reduced, the compression coil spring 15 is extended, the rod 9 is raised, and the guide member 7 is also raised. Because the air-fuel mixture has a higher flow velocity, the intake manifold 4
To the lower area of the vehicle. Further, in such a middle speed state, the air-fuel mixture is also supplied from the secondary passage 3, so that the air-fuel mixture is sufficiently uniformly distributed to each cylinder.

Next, when the engine enters a high speed state, the rod 9 further rises, and the guide member 7 is completely retracted into the primary passage 2 as shown by a broken line in the figure. In this state, the air-fuel mixture is supplied at a high speed from both the primary passage 2 and the secondary passage 3, so that the air-fuel mixture is dispersed sufficiently uniformly in the intake manifold 4, and the supply to each cylinder is also performed uniformly.

As described above, in the manifold structure of the present embodiment, it is possible to uniformly supply the air-fuel mixture to each cylinder in all regions of the engine at low, medium, and high speeds.

(Effect of the Invention) The present invention relates to a multi-cylinder internal combustion engine having an intake manifold in which a dual-type carburetor having a primary passage and a secondary passage is connected to an upstream side. The guide member is provided so as to be able to move up and down over a descending position protruding downward from the primary passage from the rising position to be drawn into the primary passage and approaching a wall side of a flow passage from the carburetor to the intake manifold. The lower end of the rod is connected to the upper end of a rod that can move up and down in parallel with the primary passage, and the lower end of the rod is connected to the diaphragm of the actuator provided outside the intake manifold, and the lower end of the rod is inserted into the negative pressure chamber in the actuator partitioned by the diaphragm. Is provided with a compression coil spring that urges the guide member to the raised position via the rod in a no-load state. In both cases, by connecting the negative pressure chamber to the intake manifold through the communication pipe, a predetermined amount of fuel can be supplied to each cylinder in all operating ranges of the engine at low, medium and high speeds. Therefore, it contributes to improvement of engine output, improvement of fuel efficiency and purification of exhaust gas.

[Brief description of the drawings]

FIG. 1 is a front sectional view showing a manifold structure of a multi-cylinder internal combustion engine according to an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1 ... Vaporizer 2 ... Primary passage 3 ... Secondary passage 4 ... Intake manifold 7 ... Guide member, 9 ... Rod 10 ... Actuator 11 ... Diaphragm 12 ... Negative pressure chamber 14 ... Communication pipe 15… Compression coil spring

Claims (1)

(57) [Scope of request for utility model registration] 1. An intake manifold for a multi-cylinder internal combustion engine having a dual carburetor having a primary passage and a secondary passage connected to an upstream side, wherein a cylindrical guide member having upper and lower ends opened is provided in the primary passage. The guide member is arranged so as to be able to move up and down over a descending position protruding downward from the primary passage from the evacuation position and approaching to the wall side of the flow passage from the carburetor to the intake manifold, and to be parallel to the primary passage. The lower end of the rod is connected to a diaphragm of an actuator provided outside the intake manifold, and a no-load state is provided in a negative pressure chamber in the actuator partitioned by the diaphragm. A compression coil spring for urging the guide member to the raised position via the rod; Intake manifold construction of a multi-cylinder internal combustion engine, characterized in that the chamber was communicated with the intake manifold via the communicating pipe.