Heat exchange – With coated – roughened or polished surface
Reexamination Certificate
2001-10-22
2003-07-22
Leo, Leonard R (Department: 3743)
Heat exchange
With coated, roughened or polished surface
C165S134100, C165S167000, C165S916000
Reexamination Certificate
active
06595271
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a heat exchanger configured of a plurality of first and second plate members stacked alternately and brazed, each forming a three-layer clad aluminum-alloy structure, or in particular to a brazed structure of a housingless type oil cooler capable of preventing the corrosion of the wall of the path of the cooling water constituting a cooling medium for an oil.
2. Description of the Related Art
In a conventional housingless type oil cooler
100
, as shown in
FIGS. 12 and 13
, a plurality of dish-shaped plates
101
having substantially the same contour are stacked and integrally brazed to each other along the arranged on the lower end of a plate stack-type core portion
102
including a plurality of the stacked plates
101
. A flat cooling water path
104
is formed between some adjacent ones of the plates
101
. A flat oil path
105
is formed between other adjacent ones of the plates
101
. These paired structures are alternated in the direction along the thickness of the plates
101
. A cooling water inlet pipe
106
and a cooling water outlet pipe
107
are mounted on the uppermost plate
101
, and a packing
108
is mounted on the seat member
103
. Heat transmission fins
109
are arranged in each of the oil paths
105
.
Each of a plurality of the plates
101
used for this housingless oil cooler
100
, as shown in
FIG. 14
, is an aluminum-alloy three-layer clad structure (three-layer structured plate member) formed of an aluminum-alloy core member
110
which is clad, on the two sides thereof, with first and second brazing material layers
111
,
112
of an aluminum alloy such as Al—Si. The flat portions of a plurality of the plates
101
are each constructed in such a manner that the first brazing material layer
111
and the second brazing material layer
112
is arranged in opposed relation to each other with the cooling water path
104
or, as the case may be, the oil path
105
therebetween. Also, the outer peripheral portion of each of the plates
101
which is located outside of the flat portion thereof is bent so that the surfaces of the first brazing material layer
111
of a given plate
101
and the second brazing material layer
112
of an adjacent plate
101
are in contact with each other.
The conventional housingless type oil cooler
100
, however, poses the problem that once the cooling water providing an oil cooling medium is degenerated and becomes corrosive, that wall of the aluminum-alloy plates
101
which is nearer to the cooling water path is easily corroded and the service life of the cooler is shortened. As a solution to this problem, an aluminum-alloy three-layer clad structure (three-layer structured plate member) has been conceived in which an aluminum-alloy sacrificing material layer is clad on that side surface of the aluminum alloy core member constituting each plate
101
which is nearer to the cooling water path and an aluminum-alloy brazing material layer is clad on the side surface of the core member nearer to the oil path. This poses another problem, however, that for lack of a brazing material in the joint between the peripheral portions of adjacent plates
101
, the peripheral portions of adjacent plates
101
cannot be brazed to each other.
As a method to solve this problem, a housingless type oil cooler (Japanese Unexamined Patent Publication No. 10-185462) of an aluminum-alloy four-layer clad structure (four-layer structured plate member) has been proposed, in which as shown in
FIG. 15
, a first aluminum-alloy sacrificing material layer
121
is clad on one side surface of the aluminum-alloy core member
120
of the plate
101
, while a second aluminum-alloy sacrificing member
122
is clad on the other side surface of the core member
120
, and the surface of the second sacrificing member
122
is clad with an aluminum-alloy brazing material layer
123
. The outer peripheral portion of each of these plates
101
is bent in such a manner that the surface of the brazing material layer
123
is in contact with the surface of the first sacrificing material layer
121
of an adjacent plate
101
. With this structure, the presence of the brazing material in the joint of the outer peripheral portion of each plate
101
improves the coupling strength and the sealability of the joint of the outer peripheral portion of each plate
101
. Nevertheless, the use of a four-layer structure for the plate
101
poses the problem of a higher material cost and the resulting higher product cost.
A three-layer structured plate member with a Zn-contained brazing material layer doubling as a sacrificing member clad on the two side surfaces of the aluminum-alloy core member may be considered as still another solution. When integrally brazing this structure in a heating furnace, however, the Zn component is liable to be evaporated on the one hand and the brazing material layer is concentrated at the joint by surface tension on the other hand. Thus, the amount of the sacrificing material is difficult to control, and the resulting insufficient corrosion resistance is liable to lead to the corrosion of the wall surface of the plate member nearer to the cooling water path.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a low-cost heat exchanger of aluminum comprising first and second three-layer structured plate members as first and second plates, respectively. Another object of the invention is to provide a heat exchanger of aluminum in which the coupling strength and the sealability of the joint of the peripheral portions of the first and second plate members can be improved while at the same time maintaining the corrosion resistance of the first and second plate members.
According to one aspect of the invention, there is provided a heat exchanger of aluminum comprising:
a plurality of first plates each constituting a three-layer structured first plate member including a first aluminum-alloy core member, a first sacrificing material layer clad on one side surface of the first core member and a first brazing material layer clad on the other side surface of the first core member; and
a plurality of second plates each constituting a three-layer structured second plate member including a second aluminum-alloy core member, a second brazing material layer clad on one side surface of the second core member and a second sacrificing material layer clad on the other side surface of the second core member. As a result, the material cost of the heat exchanger of aluminum can be reduced for a lower product cost.
A plurality of the first plate members and the second plate members are arranged alternately in the direction along the thickness thereof in such a manner that the first sacrificing material layer and the second sacrificing material layer are in opposed relation to each other with a first fluid path therebetween while the first brazing material layer and the second brazing material layer are in opposed relation to each other with a second fluid path therebetween. This assembly is heated to higher than the melting points of the first and second brazing material layers in a heating furnace or the like. In this way, each joint between the first and second plates can be positively brazed to couple them to each other while holding the first and second sacrificing material layers on the side of each of the first and second plates exposed to the corrosive environment.
The outer peripheral edge portion of each first plate member is deformed in such a manner that at least the first brazing material layer is interposed in the joint between the outer peripheral portion of the first plate member and the second plate member or the first plate member. This assembly is heated to higher than the melting points of the first and second brazing material layers in a heating furnace or the like. As a result, the joint between the outer peripheral portion of the first plate member and the second plate member or the first plate member can be positively brazed and coupl
Denso Corporation
Harness Dickey & Pierce PLC
Leo Leonard R
LandOfFree
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