Exhaust gas heat exchanger

Details Exhaust gas heat exchanger Exhaust gas heat exchanger

2002-07-24

2003-07-22

Bennett, Henry (Department: 3743)

Heat exchange

Casing or tank enclosed conduit assembly

Manifold formed by casing section and tube sheet of assembly

C165S052000, C123S568120, C060S320000

Reexamination Certificate

active

06595274

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATION
This application is based upon Japanese Patent Application No. 2001-226409, filed on Jul. 26, 2001, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exhaust gas heat exchanger for performing heat exchange between exhaust gas generated by combustion and cooling water. Specifically, the present invention relates to an exhaust gas heat exchanger for cooling the exhaust gas in an exhaust gas recirculation system (i.e., EGR system).
2. Related Art
As shown in
FIG. 1
, an exhaust gas heat exchanger for cooling the exhaust gas in an EGR system (hereinafter, referred to as an EGR gas heat exchanger) is equipped with plural laminated exhaust gas tubes
301
disposed in a tank
302
. The exhaust gas tubes
301
penetrate and are attached to a core plate
330
. A peripheral portion of the core plate
330
is folded toward the tank
302
, and is attached to an outer wall of the tank
302
. The tank
302
is closed with the core plate
330
to isolate a cooling water passage formed in the tank
302
from a bonnet
306
. A cooling water inlet pipe
304
and a cooling water outlet pipe (not shown) are disposed on the tank
302
to permit the flow of the cooling water through the tank
302
.
In this EGR gas heat exchanger, an adequate contact area is necessary for ensuring contact strength between the peripheral portion of the core plate
330
and the tank
302
. Therefore, when the core plate
330
is folded toward the tank
302
as shown in
FIG. 1
, the cooling water inlet pipe
304
must be kept away from the core plate
330
, for example, the distance l in the figure is about 20-30 mm, to obtain the adequate contact area between the core plate
330
and the tank
302
. As a result, the cooling water becomes stuck at a portion of the tank
302
between the core plate
330
and the cooling water inlet pipe
304
or between another core plate (disposed at the other side, not shown) and the cooling water outlet pipe. Accordingly, the heat exchanging efficiency would be lowered and the boiling of the cooling water may occur at the vicinity of the core plate.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an exhaust gas heat exchanger in which a cooling water pipe is disposed close to a core plate to improve the heat exchanging efficiency and resistance to boiling.
The exhaust gas heat exchanger has a tank, plural exhaust gas tubes provided in the tank through which exhaust gas flows. A water passage is defined in the tank where cooling water flows from a cooling water inlet pipe to a cooling water outlet pipe. The plurality of exhaust gas tubes are connected to core plates at an upstream side thereof and a downstream side thereof. The core plates are connected to bonnets at both sides of the tank. A peripheral portion of at least one of the core plates is folded toward the bonnet to which said at least one of the core plates is connected.
With this feature, the cooling water inlet pipe, for example, can be disposed close to the core plate at the upstream side. In this case, the cooling water can flow close to the upstream side of the plural exhaust gas tubes. As a result, the cooling water can be prevented from being stuck at the upstream side of plural exhaust gas tubes.
Preferably, the at least one of the core plates is the one disposed at the upstream side of the plural exhaust gas tubes.
Preferably, the cooling water inlet pipe or the cooling water outlet pipe is disposed on the tank at a location where the disposed distance of the pipe from the core plate is equal to or less than a diameter of the pipe.
Other features and advantages of the resent invention will become more apparent from the following detailed description made with reference to the accompanying drawings.


REFERENCES:
patent: 6247523 (2001-06-01), Shibagaki et al.
patent: 6390186 (2002-05-01), Laudic et al.
patent: 2001/0047861 (2001-12-01), Maeda et al.
patent: 3212913 (1983-10-01), None
patent: 3212914 (1983-10-01), None
patent: 406774 (1991-01-01), None
patent: A5-1895 (1993-01-01), None
patent: 2001-33187 (2001-02-01), None

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