JPH0130579Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an exhaust manifold used in a three-cylinder engine equipped with a secondary air introduction device.

(Prior art and problems with the invention) The secondary air introduction device uses exhaust pulsation to introduce secondary air into the exhaust manifold to reduce HC and CO in the exhaust gas. As shown in Publication No. 55-45053, multiple reed valves are connected to the exhaust manifold,
As shown in Japanese Utility Model Publication No. 55-40338, there is one in which one reed valve is connected to the exhaust manifold. In the latter case, since the timing of exhaust gas discharged from each cylinder is different, there is a problem in that the exhaust pulsations interfere with each other and the amount of secondary air introduced is reduced.

The present invention proposes an exhaust manifold used in a three-cylinder engine in which two exhaust ports are arranged close to each other and one exhaust port is arranged far apart, and its shape and secondary air introduction pipe. The purpose of this invention is to solve the above-mentioned problems of the latter type of secondary air introduction device by devising the position and direction of the connection.

(Means for Solving the Problems) In order to achieve the above object, the present invention aims to provide the first exhaust port among the three exhaust ports formed in the cylinder head.
3, in which the exhaust port and the second exhaust port are arranged close to each other, and the third exhaust port is arranged apart from each other;
In an exhaust manifold used in a cylinder engine and equipped with a first branch pipe, a second branch pipe, and a third branch pipe connected to each exhaust port, and a collecting pipe that collects these, the collecting pipe is installed in a horizontal section. The first branch pipe and the second branch pipe are formed in an elbow shape having a downwardly extending portion, and a first branch pipe and a second branch pipe that are shorter and closer to each other than the horizontal part of the collecting pipe extend, while the pipe is formed in an elbow shape having a downwardly extending part. A secondary pipe that extends a long third branch pipe that extends horizontally at right angles and whose tip is bent toward the third exhaust port, and that introduces air in the longitudinal direction of the third branch pipe into the bent part of the third branch pipe. It is characterized by connecting an air introduction pipe.

(Function) According to the present invention, the secondary air introduction pipe is the first and second
It is connected to the third branch pipe at a position far away from the branch pipe, and is connected to the bent portion of the third branch pipe in a direction in which air is introduced in the longitudinal direction of the third branch pipe. For this reason, the air sucked in from the secondary air inlet pipe passes in a straight direction through the longitudinal part of the third branch pipe, reaches the horizontal part of the collecting pipe, and then turns downward to the downward extension of the collecting pipe. However, this means that the suction effect due to the pulsation of the exhaust gas discharged into the third branch pipe can be most effectively received. Conversely, the influence of the pulsation of exhaust gas discharged into the first and second branch pipes on the secondary air introduction pipe is due to the fact that the flow of exhaust gas discharged into the first and second branch pipes is at a remote location. Due to the perpendicular direction, it is small. Therefore, interference due to the pulsation of the exhaust gas in the first and second branch pipes is eliminated, and the pulsation of the exhaust gas in the third branch pipe acts effectively, thereby increasing the amount of secondary air introduced.

In addition, the flow of exhaust gas discharged into the first and second branch pipes is perpendicular to the longitudinal part of the third branch pipe, and therefore to the air introduction direction of the secondary air introduction pipe. On the other hand, a suction effect can be exerted due to the ejector effect. Therefore, first,
The flow of exhaust gas in the second branch pipe effectively acts to increase the amount of secondary air intake.

(Example) Hereinafter, the present invention will be specifically described based on an illustrative example. An intake manifold 7 having three branch pipes 6a, 6b, and 6c is attached to one side of the cylinder head 1, and the exhaust manifold A is attached to the other side. Three cylinders 8 of the engine body
a, 8b, 8c are intake ports 9a, 9b, respectively.
It is connected to the three branch pipes 6a, 6b, and 6c of the branch pipe intake manifold 7 via the branch pipe 9c. The intake ports 9a, 9b, 9c are arranged as shown in FIG. 1 so that the direction of swirl in the first cylinder 8a is opposite to the direction of swirl in the second and third cylinders 8b, 8c. It is set up.

Under the influence of the arrangement of the intake ports 9a, 9b, and 9c as described above, the first exhaust port 2a communicating with the first cylinder 8a and the second exhaust port 2b communicating with the second cylinder 8b are close to each other. is arranged,
The third exhaust port 2c communicating with the third cylinder 8c is arranged apart.

As shown in FIGS. 1 and 2, the exhaust manifold A is formed by forming three branch pipes 3a, 3b, and 3c branching from a collecting pipe 4, and includes a first exhaust port 2a and a second exhaust port 2b. The first branch pipe 3a and the second branch pipe 3b connected to each of the exhaust port 2c are formed short and arranged close to each other, while the third branch pipe 3c connected to the third exhaust port 2c is formed long. and is arranged apart from the collecting pipe 4.

As shown in FIG. 2, the collecting pipe 4 is formed into an elbow shape having a horizontal portion 4a and a downwardly extending portion 4b. The first branch pipe 3a and the second branch pipe 3 are shorter than the horizontal part 4a of the collecting pipe 4 and are close to each other.
b is extended. Further, a long third branch pipe 3 extends horizontally from the horizontal part 4a of the collecting pipe 4 at a substantially right angle thereto, and has a tip 12 bent toward the third exhaust port 2c.
c is extended.

A secondary air introduction port 5 is formed in the bent portion 13 near the tip of the third branch pipe 3c, and a secondary air introduction pipe 10 provided with a reed valve 11 is connected to this port. This reed valve 11 is the third branch pipe 3c.
The pulsating effect of the exhaust gas discharged into the first and second
The valve opens due to the ejector effect of the exhaust gas discharged into the branch pipes 3a and 3b, and secondary air is introduced into the exhaust manifold A.

(Effect of the invention) The present invention determines the shape of the exhaust manifold and the connection position and direction of the secondary air introduction pipe as described above, so that the pulsation of the exhaust gas discharged into the third branch pipe can be effectively utilized. , and the secondary air can be effectively introduced into the exhaust manifold due to the ejector effect of the exhaust gas discharged into the first and second branch pipes, and the amount of secondary air introduced can be increased. .

[Brief explanation of the drawing]

FIG. 1 is a plan view of an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line -- in FIG. 1... Cylinder head, 2a... First exhaust port,
2b...second exhaust port, 2c...third exhaust port,
3a...first branch pipe, 3b...second branch pipe, 3c...third branch pipe, 4...collecting pipe, 4a...horizontal part, 4b...downward extending part, 10...secondary air introduction pipe, 13...third Bend part of branch pipe.

Claims (1)

[Scope of utility model registration request] Among the three exhaust ports formed in the cylinder head, the first exhaust port and the second exhaust port are arranged close to each other, and the third exhaust port is arranged far apart. In the exhaust manifold, the exhaust manifold is provided with a first branch pipe, a second branch pipe, and a third branch pipe connected to each exhaust port, and a collecting pipe that collects these pipes, with the collecting pipe extending horizontally and downwardly. A first branch pipe and a second branch pipe are formed in an elbow shape having a section, and a first branch pipe and a second branch pipe are extended from the horizontal part of the collecting pipe in a shorter dimension and close to each other. a secondary air introduction pipe for introducing air in the longitudinal direction of the third branch pipe into the bending part of the third branch pipe; An engine exhaust manifold characterized by a connection.