Laminated type heat exchanger

According to the present invention, the tube element includes a connecting portion for connecting the pair of core plates at an upstream air side, an extending portion extending from each of the connecting portions of the core plate at the upstream air side and having a fin connecting portion connected to the corrugated fin, and a further upstream end portion of the extending portion located at an upstream side of the fin connecting portion which is located away from the corrugated fin to form a predetermined gap with the corrugated fin so as to communicate with the air passage. The extending portion including the fin connecting portion closes the whole space between the tube elements and the adjacent corrugated fins at the more upstream air side of the refrigerant passage, so that the air entering between the tube elements and the adjacent corrugated fins can be substantially shut off.

CROSS REFERENCE TO RELATED APPLICATION 
This application is based upon and claims priority of Japanese Patent 
Application No. 7-97101 filed on Apr. 21, 1995, the contents of which are 
incorporated herein. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a laminated type heat exchanger, which is 
suitably employed as a refrigerant evaporator of an automotive air 
conditioner. 
2. Description of Related Art 
In a well-known conventional laminated type heat exchanger for an 
automotive air conditioner, a corrugated fin and a tube element including 
a pair of symmetrical core plates are laminated to each other. For 
example, in JP-A-64-41794, and as shown in FIG. 7, the upstream end (with 
respect to the air flow) 4g of core plates 4 which together form a tube 
element 2 is spaced from a corrugated fin 3 as shown in FIG. 7, so that 
condensed water can be drained through corrugated fin 3 and the vent 
portion can be prevented from being clogged due to the generation of the 
condensed water. 
However, in the structure of tube element 2 disclosed in the 
above-described prior art, dust and dirt contained in the air passing 
through a heat exchanging portion enter through a gap 6 between the 
upstream end 4g of core plate 4 and the upstream end portion of corrugated 
fin 3 and adhere to tube wall 5a of the refrigerant passage. In this case, 
when the dust contains some ingredients which promote corrosion of tube 
wall 5a such as copper particles, tube wall 5a of tube element 2 will 
corrode causing a refrigerant leak. 
SUMMARY OF THE INVENTION 
In light of the above-described problem, the present invention has an 
object to provide a laminated type heat exchanger which can prevent dust 
and dirt contained in the flowing air from directly contacting the tube 
wall of the tube element and thus prevent corrosion of the tube element 
which eventually will lead to the refrigerant leaking. 
According to the present invention, a laminated type heat exchanger 
includes a plurality of tube elements forming a refrigerant passage in 
which refrigerant flows by connecting a pair of basin-shaped core plates 
at the outer peripheries thereof in such a manner that air passages are 
formed between adjacent tube elements. A corrugated fin is disposed in the 
air passage and thermally connected at both sides of the tube elements. 
Heat exchange occurs between air flowing in the air passage and the 
refrigerant flowing in the refrigerant passage to exchange heat to cool 
the air. The tube element includes a connecting portion for connecting the 
pair of core plates at an upstream air side, an extending portion 
extending from each of the connecting portions of the core plate at the 
upstream air side and a fin connecting portion connected to the corrugated 
fin. The most upstream end portion of the extending portion located at an 
upstream side of the fin connecting portion is spaced away from the 
corrugated fin to form a predetermined gap with the corrugated fin so as 
to communicate with the air passage. 
According to the above configuration, the extending portion including the 
fin connecting portion closes the entire space between the tube element 
and the adjacent corrugated fins at the upstream air side of the 
refrigerant passage, so that the air which otherwise would enter from 
between the tube element and the adjacent corrugated fins can be 
substantially shut off. As a result, ingredients which promote corrosion 
such as dust and dirt contained in the air passing between the adjacent 
corrugated fins can be prevented from adhering to the connecting portion 
of the core plates and the tube wall of the refrigerant passage, thus 
improving corrosion resistance of the tube element and preventing the 
refrigerant from leaking. By forming a gap having a predetermined distance 
between the most upstream end portion of the extending portion and the 
corrugated fin, a part of the air flowing into the space between the 
adjacent corrugated fins can be sent to the air passage through the 
corrugated fins. The air flow resistance caused by the air flowing into 
the space between the adjacent corrugated fins can be reduced. 
When the core plate is formed in the same shape at the both air upstream 
and downstream sides in the longitudinal direction, a symmetrical core 
plate can be made. Thus, only one kind of core plate is applied to form a 
tube element which reduces the number of parts. 
Other objects and features of the invention will appear in the course of 
the description thereof, which follows.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS 
Preferred embodiments where the present invention is applied to a 
refrigerant evaporator of an automotive air conditioner are hereinafter 
described with reference to the accompanying drawings, 
According to embodiment shown in FIGS. 1-3, FIG. 2 is a view taken from the 
upstream direction of the air passing through a refrigerant evaporator 1 
of an automotive air conditioner to which the present invention is 
applied. 
Refrigerant evaporator 1 includes a plurality of tube elements 2 each 
forming a refrigerant passage 5 between core plates 4, i.e., a pair of 
symmetrical basin-shaped core plates connected at outer peripheries 
thereof and corrugated fins 3 (hereinafter called fins 3) for improving 
heat exchange performance. 
Core plate 4 is formed by pressing an aluminum-clad plate, clad with 10-15% 
of aluminum-brazed material on both surfaces. 
As shown in FIG. 3, core plate 4 is substantially rectangular and has at a 
top portion thereof an inlet tank chamber 7a for forming an inlet tank 7 
and an outlet tank chamber 8a for forming an outlet tank 8. The portion 
between inlet tank chamber 7a and outlet tank chamber 8a of core plate 4 
serves as refrigerant passage 5 communicating with both inlet and outlet 
tank chambers 7a and 8a. Tube element 2 is formed by a pair of core plates 
4 including inlet tank chamber 7a, outlet tank chamber 8a and refrigerant 
passage 5 being connected together, In a pair of core plates 4, the 
concave surface of one core plate faces the concave surface of the other 
core plate. The outer peripheries of core plates 4 serve as a connecting 
portion 4a for connecting core plates 4 to each other. The shapes of the 
upstream end and the downstream end of core plates 4 with respect to the 
air flow are described later. 
Each of inlet and outlet tank chambers 7a and 8a is formed in a basin shape 
so as to protrude in a laminated direction of tube element 2, and these 
chambers, 7a and 8a, have communicating holes 71a and 81a, respectively. 
A center rib 4b extending vertically is provided at the center of the width 
of core plate 4 to form the substantially U-shaped refrigerant passage 5. 
The portion serving as refrigerant passage 5 has many protruding ribs 4c 
on the entire surface thereof. When a pair of core plates 4 are connected 
to form tube element 2, ribs 4c face each other crosswise, and thereby the 
heat exchanging area of the refrigerant is increased and the flow of the 
refrigerant is made turbulent to improve the heat conductivity. 
As stated above, tube element 1 is formed by connecting two core plates 4. 
Core plates 4, of which left and right parts are symmetrical, are 
connected to each other by brazing connecting portion 4a. Refrigerant 
passage 5 is formed in tube element 2 perpendicularly with respect to the 
vertical direction of FIG. 1. 
Fin 3 is formed by folding a thin plate into a corrugated shape such that 
the air can flow between each folded plate surfaces. The plate surface of 
fin 3 is provided with louvers 3a to promote the heat exchanging 
efficiency. 
As shown in FIG. 3, the plurality of tube elements 2 are laminated 
substantially perpendicularly with respect to the air flow, and the air 
passes between tube walls 5a of refrigerant passages 5 on the adjacent 
tube elements 2, serving as an air passage. Fin 3 is disposed in the air 
passage and connected to adjacent tube walls 5a of refrigerant passages 5. 
When each tube element 2 and its respective fin 3 are laminated, an end 
plate is connected to the end portions of tube element 2 and fin 3, so 
that the right and left end walls and the top and the bottom end walls of 
refrigerant evaporator 1 are closed from the outside. After tube elements 
2 and fins 3 are laminated and temporarily assembled, the assembly is 
integrally brazed by being heated in a furnace (not shown). 
When tube elements 2 are laminated, the adjacent inlet tank chambers 7a 
communicate with each other through communicating holes 71a of inlet tank 
chambers 7a in order to form inlet tank 7. Also, when tube elements 2 are 
laminated, the adjacent outlet tank chambers 8a communicate with each 
other through their communicating holes 81a of outlet tank chambers 8a in 
order to form outlet tank 8. However, when laminated, communicating hole 
71a of inlet tank chamber 7a and communicating hole 81a of outlet tank 
chamber 8a at both ends of tube element 2 are closed with the end plates. 
An inlet pipe 9a is connected to inlet tank 7 to introduce the refrigerant 
into each tube element 2 from the refrigerant circuit (not shown). An 
outlet pipe 9b is connected is connected to outlet tank 8 to introduce the 
refrigerant flowing out from each tube element 2 into the refrigerant 
circuit. 
FIG. 1 is a cross-sectional view of tube element 2 and fin 3 along the 
parallel plane with respect to the air flow direction at the upstream side 
thereof. 
As shown in FIG. 1, each core plate 4 forming tube element 2 is bent in the 
direction away from each other at upstream from connecting portion 4a. 
Each cure plate 4 extends to the upstream air side from a bent portion 4d 
and is connected to fin 3 at a fin connecting portion 4e which is at a 
more upstream side of the air flow than connecting portion 4a. At fin 
connecting portion 4e for connecting core plate 4 and fin 3, each core 
plate 4 is bent again to extend further toward the upstream air side. As 
shown in FIG. 1, the end portions 4f of each respective cure plate 4 are 
bent towards each other. 
Since core plate 4 is formed as described above, fin connecting portion 4e 
is disposed at a more upstream side of the air flow than tube wall 5a 
which is at the upstream side of refrigerant passage 5, and end portion 4f 
is disposed at a upstream side of the air flow than fin connecting portion 
4e. 
A gap 6 having a predetermined distance is formed between end portion 4f of 
core plate 4 and the upwind end portion of fin 3. Core plate 4 is bent at 
fin connecting portion 4e so that the distance between end portion 4f of 
core plate 4 and fin 3 is gradually reduced in the flowing direction of 
the air. Gap 6 communicates with the air passage between adjacent tube 
elements 2 via fin 3. 
Connecting portion 4a and fin connecting portion 4e in core plate 4 both 
include flat surfaces each having an appropriate width so that these flat 
portions are brazed firmly. 
Although it is not illustrated, the air upstream and downstream sides of 
respective core plate 4 have the same shape in the longitudinal direction. 
The downstream end in the air flow of core plate 4 is symmetrically formed 
with respect to center rib 4b. 
An operation of the present embodiment is hereinafter explained. 
After the refrigerant flows into each tube element 2 through inlet pipe 9a 
from the refrigerant circuit and passes refrigerant passage 5, the 
refrigerant exchanges heat with the air passing in the air passage and the 
refrigerant is sent out to the refrigerant circuit through outlet pipe 9b. 
On the other hand, the air passes through the air passages shown in FIG. 2 
and flows from the left to right in FIG. 1. 
Each core plate 4 for forming tube element 2 is bent away from each other 
at a more upstream position than connecting portion 4a to form portion 4d. 
Each core plate 4 extends to the upstream air side from bent portion 4d to 
form portion 4e and is connected to fin 3. Since fin connecting portion 4e 
for connecting each core plate 4 and fin 3 is located at a more upstream 
side of the air flow than connecting portion 4a, some of the air passing 
through refrigerant evaporator 1 cannot go into the space between adjacent 
fins 3 and core plate 4, because the air flow is actually obstructed by an 
extending portion 10 extending from bent portion 4d of core plate 4. Thus, 
the air cannot flow into the sides of connecting portion 4a and tube wall 
5a of refrigerant passage 5. If the air passing through refrigerant 
evaporator 1 contains corrosion-promoting ingredients such as copper and 
these corrosion-promoting ingredients adhere to extending portion 10 
extending from bent portion 4d, such ingredients will be prevented from 
adhering to connecting portion 4a and tube wall 5a of refrigerant passage 
5. As a result, connecting portion 4a and tube wall 5a of refrigerant 
passage 5, which are the most important portions to prevent the leakage of 
the refrigerant, can be prevented from being corroded, improving the 
corrosion resistance. The prevention of corrosion eliminates holes caused 
by the corrosion of connecting portion 4a and tube wall 5a of refrigerant 
passage 5 and the refrigerant is prevented from leaking. 
Since gap 6 has a predetermined distance communicating with the air passage 
through fin 3 some of the air having flowed between core plate 4 and 
adjacent fins 3 flows into this gap 6. The air having flowed into gap 6 
can enter the communicating air passage through fin 3, so that air flow 
resistance can be reduced. 
Moreover, because each core plate 4 has a symmetrical shape with respect to 
center rib 4b, the number of parts for presswork can be reduced as well as 
the number of dies for the presswork. Each core plate 4 has a symmetrical 
shape and a gap which has a predetermined distance communicating with the 
air passage via fin 3 so that the air passing between core plate 4 and the 
adjacent fins 3 can have a larger flowing area at the downstream end of 
the air, thus the air flow resistance can be further reduced. 
Another embodiment is hereinafter described with reference to FIG. 4. 
In this embodiment, core plate 4 extends from bent portion 4d toward tube 
wall 5a at an upstream air side of refrigerant passage 5 and core plate 4 
is connected to fin 3 at a more upstream side of the air flow than tube 
wall 5a of refrigerant passage 5. 
FIG. 4 is a cross-sectional view of tube element 2 and fins 3 along the 
parallel plane with respect to the air flow direction at the upstream side 
thereof. 
Refrigerant evaporator 1, similar to the previous embodiment, includes tube 
element 2 where a pair of core plates 4 are connected face to face and 
both tube element 2 and fins 3 are laminated and connected with each other 
by brazing. 
As shown in FIG. 4, each core plate 4 for forming tube element 2 is bent so 
that bent portion 4d is formed in a substantially U-shape and extends from 
bent portion 4d to tube wall 5a at the upstream air side of refrigerant 
passage 5. End portion 4e of each core plate 4 is connected to fin 3 
between bent portion 4d and tube wall 5a at the upstream air side of 
refrigerant passage 5, thereby tube wall 5a is actually shut out from the 
air flow. Bent portion 4d is positioned at the most upstream side of the 
air flow of core plate 4. Gap 6 having a predetermined distance is formed 
between portion 10, extending from bent portion 4d of core plate 4 to fin 
connecting portion 4e, and fin 3 facing portion 10. This gap 6 faces the 
air passage through fin 3. 
Since the other structure is the same as in the previous embodiment, the 
explanation is omitted. 
An operation of this embodiment is hereinafter described. 
This embodiment also has the same effect as the previous embodiment. In 
addition, by bending bent portion 4d of core plate 4 in a substantially 
U-shape and by extending core plate 4 from bent portion 4d to tube wall 5a 
at the upstream air side of refrigerant passages to connect it to fin 3, 
portion 10 extending from bent portion 4d to fin connecting portion 4e can 
be overlapped on connecting portion 4a of core plate 4 so that the 
thickness of connecting portion 4a can be approximately doubled. Thus, 
without changing the thickness of core plate 4, corrosion resistance of 
core plate 4 can be further improved in comparison with the previous 
embodiment. 
Another embodiment is hereinafter described with reference to FIG. 5. 
In this embodiment as shown in FIG. 5, a portion 10 extends from portion 4d 
toward connected portion 4a where tube wall 5a of refrigerant passage 5 of 
core plate 4 and fin 3 are connected to each other. A portion extending 
from bent portion 4d to fin connecting portion 4e of core plate 4 and 
portion 10 make contact with each other in a wide range. Such a structure 
of the end portion of tube element 2 enables it to cover tube wall 5a of 
refrigerant passage 5 completely, thus further improving corrosion 
resistance of core plate 4. 
Another embodiment is hereinafter described with reference to FIG. 6. 
In this embodiment as shown in FIG. 6, bent portion 4d of core plate 4 is 
bent toward tube wall 5a of refrigerant passage 5, and end portion 4f of 
core plate 4 slightly contacts corrugated fin 3. In this case, portion 10 
extending from bent portion 4d of core plate 4 to fin connecting portion 
4e and connecting portion 4a may be slightly separated. 
According to the above-described embodiment, each core plate 4 for forming 
a tube element is symmetrical with respect to the center rib, however, 
bent portion 4d and fin connecting portion 4e can be disposed only at the 
upstream side of the core plate with respect to the air flow. In other 
words, when at least the upstream side of the air flow in each core plate 
4 has the above-mentioned structure, the air flow can be shut off by the 
portion from bent portion 4d of each core plate 4 to the fin connecting 
portion 4e, which are disposed at the more upstream side of the air flow 
than tube wall 5a of refrigerant passage 5. Corrosion-promoting 
ingredients contained in the air passing through a laminated heat 
exchanger can be effectively prevented from adhering to tube wall 5a of 
refrigerant passage 5, and corrosion resistance of core plate 4 can be 
improved. Moreover, the wind resistance can be decreased in the same 
manner as the previously-described embodiments. 
Although the present invention has been fully described in connection with 
the preferred embodiments thereof with reference to the accompanying 
drawings, it is to be noted that various changes and modifications will 
become apparent to those skilled in the art. Such changes and 
modifications are to be understood as being included within the scope of 
the present invention as defined by the appended claims.