Mounting structure for EGR valve or EGR tube

Details Mounting structure for EGR valve or EGR tube Mounting structure for EGR valve or EGR tube

1999-12-23

2001-06-12

Wolfe, Willis R. (Department: 3747)

Internal-combustion engines

Charge forming device

Exhaust gas used with the combustible mixture

C123S568170, C123S568180

Reexamination Certificate

active

06244255

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a mounting structure in which an EGR valve or an EGR tube is mounted to an intake manifold made of aluminum.
2. Description of the Related Art
A known EGR (exhaust gas re-circulating system) for decreasing NOx and improving the fuel consumption in an internal engine is shown in FIG.
4
. In this system, an exhaust gas introduced from an exhaust manifold
1
to an EGR tub e
2
is flow controlled by an EGR valve
3
and is then returned back via an intake manifold
4
to a combustion chamber. The problem is that while the EGR valve
3
is mounted by tightening nuts
6
onto stud bolts
5
implanted to the intake manifold
4
, increase in temperature by the exhaust gas at the female threads in the intake manifold
4
into which the stud bolts
5
are screwed may decline the physical strength. Particularly, when the intake manifold
4
is made of aluminum, its physical strength may be declined even to a half by a temperature of almost 250° C. hence failing to maintain the axial force of holding the stud bolts
5
and causing leakage of the exhaust gas. For compensation, as shown in an enlarged primary part view of
FIG. 5
, a cooling water passage
4
b
is provided adjacent to the female threads
4
a
in the intake manifold
4
and is connected to water hoses
7
at the outside for supplying a cooling water to cool down the female threads
4
a
. This will however increase the number of relevant components, the overall weight, and thus the manufacturing cost.
In addition, as shown in
FIG. 6
, a mounting portion
10
a
of an EGR tube
10
may be joined to the intake manifold
4
made of aluminum with the use of stud bolts
5
and nuts
6
. This structure also requires cooling of the female threads for the stud bolts
5
in the intake manifold
4
with cooling water.
SUMMARY OF THE INVENTION
It is an object of the present invention, in view of the above problems, to provide a mounting structure for EGR valve or EGR tube, which structure does not require cooling water passages or water hoses, while rigid mounting can be made without declining the axial force for holding bolts.
According to the present invention, there is provided a mounting structure for an EGR valve or an EGR tube. The EGR valve or the EGR tube is made of stainless steel or cast iron which is high in the physical strength at a high temperature. The EGR valve or the EGR tube is mounted to an intake manifold made of aluminum by means of bolts or stud bolts. The EGR valve or the EGR tube has female threads provided therein into which the bolts or stud bolts are screwed. The intake manifold has through holes provided therein through which the bolts or stud bolts extend.
Accordingly, the bolts or stud bolts may be inserted into the through holes in the aluminum intake manifold and may be screwed into the female threads in the EGR valve or EGR tube. Therefore, the EGR valve or the EGR tube can be fixedly joined to the intake manifold. Because the EGR valve or EGR tube is made of stainless steel or cast iron which is high in the physical strength in a high temperature, the female threads of the EGR valve or the EGR tube maintain the axial force of the bolts or stud bolts not to be declined even when they are exposed to a higher temperature caused by heat of the exhaust gas. Therefore, no leakage of the exhaust gas may be caused. Also, the need of cooling passages or water hoses for cooling the female threads in a conventional manner can be eliminated and both the overall weight and the cost can thus be reduced. Moreover, the space required for the passage or the water hoses is not needed thus making the overall structure compact in size.


REFERENCES:
patent: 1793556 (1931-02-01), Moore
patent: 4329965 (1982-05-01), Ueda et al.
patent: 4381755 (1983-05-01), Caracciolo
patent: 4909036 (1990-03-01), Kimura
patent: 4938176 (1990-07-01), Tanaka et al.
patent: 5909725 (1999-06-01), Balsdon et al.
patent: 5970960 (1999-10-01), Azuma
patent: 5988148 (1999-11-01), Astner et al.
patent: 2-227545 (1990-09-01), None
patent: 10-089160 (1998-04-01), None

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