Structure for introducing secondary air into exhaust path of...

Details Structure for introducing secondary air into exhaust path of... Structure for introducing secondary air into exhaust path of...

1999-08-31

2001-12-11

Denion, Thomas (Department: 3748)

Power plants

Internal combustion engine with treatment or handling of...

By means producing a chemical reaction of a component of the...

C060S289000, C060S293000, C123S04182R

Reexamination Certificate

active

06327853

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure for introducing secondary air into an exhaust path of an internal combustion engine. More particularly, the present invention relates to a structure for introducing secondary air into an exhaust path of an internal combustion engine by which the preheating effect of introduced secondary air is improved and the re-combustion property of exhaust gas is enhanced.
2. Description of the Related Art
Conventionally, it is well-known that secondary air is introduced into an exhaust path of an internal combustion engine and re-combusted in the exhaust path, so that HC and CO contained in exhaust gas, which are unburned components, are reduced. In this case, at a position where the temperature of the exhaust gas is high, re-combustion of exhaust gas is more effectively carried out. Therefore, the secondary air is introduced into a portion of the exhaust path which is located as close to an exhaust port as possible.
In the secondary air introducing structure from which secondary air is introduced into the exhaust path of the internal combustion engine shown in
FIG. 2
, there is formed an exhaust path
105
in a cylinder section
100
composed of a cylinder block
102
and a cylinder head
101
. In the periphery of the exhaust path
105
, there are formed water jackets
119
,
120
,
121
, and secondary air is introduced into the exhaust path
105
.
The water jacket
120
is formed by a water jacket cover
130
attached to an outer face of the cylinder section
100
. Outside the water jacket cover
130
, there is provided a valve cover
131
. By the water jacket cover
130
and the valve cover
131
, a valve chamber
132
is formed. In the valve chamber
132
, there is provided a valve
133
.
In the water jacket cover
130
, there is formed an opening
134
. In the cylinder section
100
, there is formed a communicating path
135
which is communicated with the opening
134
. The valve chamber
132
and the exhaust path
105
are communicated with each other by the opening
134
and the communicating path
135
(shown in Japanese Patent Unexamined Publication No. Hei. 5-79325).
Accordingly, after secondary air has been introduced from an air tube
136
into the valve chamber
132
, it passes through a valve
133
when the valve
133
is opened by the pulsation effect of exhaust gas. Then, the secondary air is introduced into the exhaust path
105
via the opening
134
and the communicating path
135
. In the exhaust path
105
, exhaust gas is subjected to re-combusting by the secondary air.
The conventional secondary air introducing structure by which secondary air is introduced into the exhaust path of the internal combustion engine is composed as described above. Accordingly, the water jackets
120
,
121
are arranged between the valve
133
and the exhaust path
105
. Heat of exhaust gas flowing in the exhaust path
105
is intercepted by these water jackets
120
,
121
. Therefore, no heat of exhaust gas is transmitted to the valve
133
side. As a result, it is possible to prevent the valve
133
from being affected by heat.
However, the following problems may be encountered in the above conventional secondary air introducing structure from which secondary air is introduced into the exhaust path of the internal combustion engine. In the above conventional secondary air introducing structure, the secondary air introducing path, which is composed of the valve chamber
132
, opening
134
and communicating path
135
, is formed being protruded onto the side of the cylinder section
100
. Therefore, the path structure is complicated. Further, the exhaust port of secondary air, which is an opening of the communicating path
135
on the exhaust path
105
side, is distant from the exhaust valve
107
. Therefore, secondary air can not be preheated to a sufficiently high temperature. Accordingly, the temperature of mixture, in which exhaust gas is mixed with secondary air, is not raised to a sufficiently high temperature. As a result, the function of a catalyst is lowered, and re-combustion of exhaust gas is not sufficiently carried out.
SUMMARY OF THE INVENTION
The present invention has been accomplished to solve the above problems caused in the conventional secondary air introducing structure from which secondary air is introduced into the exhaust path of the internal combustion engine. It is an object of the present invention to provide a secondary air introducing structure from which secondary air is introduced into the exhaust path of the internal combustion engine by which the introduced secondary air can be sufficiently preheated, so that the function of the catalyst can be prevented from deteriorating and the re-combustion property of exhaust gas can be enhanced.
To solve the above object, there is provided a structure of introducing secondary air into an exhaust path of an internal combustion engine, wherein a secondary air introducing path is formed in a cylinder head along an exhaust port.
Due to the structure described above, secondary air is effectively heated by heat retained in the exhaust gas flowing in the exhaust port. Therefore, the secondary air is heated to a sufficiently high temperature. Accordingly, it is possible to raise the temperature of mixture of exhaust gas and secondary air. Due to the foregoing, it is possible to prevent the function of the catalyst from deteriorating, and the re-combustion property of exhaust gas can be enhanced.
In addition, the secondary air is fed by an air pump with pressure, and an outlet of the secondary air introducing path is directed to an exhaust valve side. Accordingly, secondary air can be sufficiently supplied, and the introducing position of secondary air is close to the exhaust valve.
As a result, exhaust gas of high temperature and sufficiently preheated secondary air, the volume of which is sufficiently large, are mixed with each other, and the temperature of the mixture can be more raised. Therefore, the re-combustion property of exhaust gas can be more enhanced.
Further, the secondary air introducing path is formed between an exhaust port and an upper face of the cylinder head. Therefore, the secondary air introducing path can be formed without being affected by the exhaust manifold. Accordingly, the secondary air introducing path can be easily maintained and removed. Usually, the exhaust manifold are incorporated into an internal combustion engine in such a manner that it hangs from the exhaust port. However, when the secondary air introducing path and the secondary air path are provided between the exhaust manifold and the engine body, the maintenance work becomes difficult and further it becomes difficult to remove those paths.
Moreover, a water jacket may be formed between the secondary air introducing path and the upper face of the cylinder head. Therefore, even when exhaust gas of high temperature flows backward into the secondary air introducing path which is communicated with the exhaust port, an upper portion of the cylinder head is cooled by cooling water flowing in the water jacket.
As a result, it is possible to prevent the occurrence of heat deterioration of packing provided between the cylinder head and the cylinder head cover, and also it is possible to prevent the occurrence of heat deterioration of gasket provided between the secondary air path forming member, which is attached to a peripheral wall of the cylinder head, and the cylinder head. Consequently, it is unnecessary to use expensive heat-resistant material for these parts.


REFERENCES:
patent: 3537257 (1970-11-01), Webster et al.
patent: 4387565 (1983-06-01), Otani et al.
patent: 4430857 (1984-02-01), Ikenoya et al.
patent: 4434615 (1984-03-01), Ikenoya et al.
patent: 4539812 (1985-09-01), Rezy
patent: 4558670 (1985-12-01), Trihey
patent: 5657628 (1997-08-01), Takeuchi
patent: 5761904 (1998-06-01), Nakayama
patent: 6085519 (2000-07-01), Prior et al.

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