JPH10231722A - Exhaust manifold - Google Patents

Abstract

PROBLEM TO BE SOLVED: To activate a catalyst rapidly, and improve purifying performance by arranging a valve having a center hole on an upstream side of the catalyst in an exhaust manifold freely to open and close, and arranging a center catalyst having fine cell density on the center part of the catalyst. SOLUTION: A valve 5 provided on a part of a muffler part C upstream from a catalyst 3 is formed on a center part by penetrating a center hole 5a, and is constituted freely to open and close in an exhaust manifold 1. A center catalyst 4 having a fine cell density of a carrier arranged in a fitting condition arranged in a recessed part 3a formed upstream from the catalyst 3, and the center hole 5a, are arranged on a center part matched with each other. Since exhaust gas which is collected from each cylinder of an engine in the muffler part C, collides with the vicinity of the muffler part C in the way of passing the center hole 5a at the time of closing the valve 5, an exhaust temperature is raised, and the exhaust gas collides with the center catalyst 4 concentrically. It is thus possible to improve purifying performance of exhaust gas since the center catalyst 4 is reacted rapidly and is activated in an early stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an exhaust manifold.

[0002]

2. Description of the Related Art Conventionally, in an exhaust manifold, as shown in a schematic view of FIG. 7, a catalyst 3 is mounted in a storage portion 2e formed on a downstream side of a collecting portion C of branch pipes 2a and 2d. An O ₂ sensor 8 is provided in the collecting section C. The exhaust gas from each cylinder is collected once in the collecting section C, and then diffused in front of the catalyst 3 to pass through the catalyst 3. In the conventional structure, since the exhaust gas is uniformly applied to the entire area of the catalyst 3, it takes a long time to increase the temperature of the catalyst 3, the catalyst activity becomes slow, and the purification of the exhaust gas is performed. There was a problem that the performance was inferior. In order to activate the catalyst 3 at an early stage, as shown in FIG.
Although there is a structure provided with a heater 51, it is difficult to obtain a sufficient amount of heat to activate the catalyst 3 in a short time, and a large amount of electricity is required to operate the heater 51. However, there is a problem that the whole apparatus becomes a large-scale apparatus.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide an exhaust manifold capable of quickly activating a catalyst and improving purification performance. The gist of the invention is that a valve having a central hole is provided so as to be openable and closable on an upstream side of the catalyst in an exhaust manifold containing a catalyst, and a central catalyst having a fine cell density is provided in a central portion of the catalyst. It is.

[0004]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an exhaust manifold 1. Branch pipes 2 a, 2 b, 2 c, and 2 d connected to the cylinders of each engine are located upstream of the exhaust manifold 1.
The branch pipes 2a, 2b, 2c, 2d are gathered at a gathering portion C, and an O ₂ sensor 8 is provided in this portion, and a downstream storage portion 2e is provided. In this example, a valve 5 is provided in the upstream part of the catalyst 3 at the gathering portion C so that the valve 5 can be opened and closed. As shown in the top view, a central hole 5a is formed in the center portion so as to be opened and closed in the exhaust manifold 1 by rotating the connected shaft 7 via the actuator 6.

As shown in the top view of FIG. 5 and the enlarged sectional view of FIG. 6, a concave portion 3a is formed on the upper surface side of the catalyst 3 in this embodiment.
The central catalyst 4 is formed in a structure in which the cell density of the carrier is made small, and the central catalyst 4 and the central hole 5a of the valve 5 are provided.
Are arranged at the matching central position.

In such a structure, the exhaust gas discharged from each cylinder of the engine is supplied to the branch pipes 2a, 2b, 2c, 2
1, the exhaust gas collides at the collecting portion C in the state of FIG. 1 because the valve 5 is closed, so that the exhaust gas collides near the collecting portion C to pass through the central hole 5a.
The exhaust temperature rises due to the collision, and the center hole 5a
And the exhaust gas intensively collides with the central catalyst 4.
As a result, the central catalyst 4 having a small cell density reacts quickly, and the central catalyst 4 is activated at an early stage, thereby purifying exhaust gas at an early stage and improving purification performance. Therefore, even when the catalyst 3 is inactive, the central catalyst 4 is activated at an early stage, and good purification performance can be achieved at an early stage.

When the temperature of the catalyst 3 also rises and the catalyst 3 is activated, the valve 5 is opened via the actuator 6 as shown in FIG. 2, and in this state of FIG. Since the valve 5 is erected in the direction shown in FIG. 3, the valve 5 serves as a partition wall as shown in the top view of FIG.
From each cylinder of the engine to the branch pipes 2a, 2b, 2c,
The interference of the exhaust gas discharged through the 2d at the collecting portion C can be satisfactorily prevented at the collecting portion C. At the collecting portion C, the collision of the exhaust gas is alleviated, and the exhaust loss becomes extremely small. 5 downstream catalyst 3
Therefore, the exhaust gas hits the catalyst 3 evenly and the purification performance is improved.

Therefore, in this embodiment, when the catalyst 3 is inactive, as shown in FIG. 1, the valve 5 is closed and the exhaust gas collides with the collecting portion C, so that the temperature of the exhaust gas is increased and the central hole 5a is raised.
, The exhaust gas is applied to the central catalyst 4 to activate the central catalyst 4 at an early stage to purify the exhaust gas. When the catalyst 3 is activated, as shown in FIG. The catalyst 3 reduces the exhaust loss by preventing the interference of the exhaust gas from the cylinder, and prevents the decrease in the engine output.
The exhaust gas can be evenly applied to the entire region to improve the purification performance.

[0009]

The exhaust manifold of the present invention
A valve having a central hole is provided so as to be openable and closable upstream of the catalyst in an exhaust manifold containing the catalyst, and a central catalyst having a fine cell density is provided in a central portion of the catalyst, so that the catalyst cannot be used. At the time of activation, the valve is closed and the exhaust gas is concentrated in the central hole, the exhaust gas is intensively applied to the central catalyst, and the central catalyst can be activated early to purify the exhaust gas satisfactorily. At the time of activation, there is an effect that the exhaust gas can be evenly applied to the entire area of the catalyst in a state where the exhaust loss is reduced by opening the valve to improve the purification performance.

[Brief description of the drawings]

FIG. 1 is a sectional configuration view of an exhaust manifold in a closed state of a valve.

FIG. 2 is a sectional configuration diagram of an exhaust manifold in a state where a valve is opened.

FIG. 3 is a top view when the valve is opened.

FIG. 4 is an enlarged top view of the valve.

FIG. 5 is an enlarged top view of the catalyst.

FIG. 6 is an enlarged sectional view showing an arrangement state of a center catalyst.

FIG. 7 is a schematic configuration diagram of a conventional exhaust manifold.

FIG. 8 is a schematic configuration diagram of a different conventional exhaust manifold.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exhaust manifold 2a, 2b, 2c, 2d Branch pipe 2e Storage part 3 Catalyst 3a Depression 4 Central catalyst 5 Valve 5a Central hole 6 Actuator 7 Shaft C Collecting part

Claims (1)

[Claims] 1. A valve having a central hole is provided so as to be openable and closable on an upstream side of the catalyst in an exhaust manifold containing the catalyst, and a central catalyst having a fine cell density is provided in a central portion of the catalyst. An exhaust manifold characterized by the following.