Heat exchange – Side-by-side tubular structures or tube sections – With manifold type header or header plate
Reexamination Certificate
1997-07-11
2001-05-08
Atkinson, Christopher (Department: 3743)
Heat exchange
Side-by-side tubular structures or tube sections
With manifold type header or header plate
C165S153000, C062S515000
Reexamination Certificate
active
06227290
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laminated heat exchanger used in the cooling cycle or the like in an air conditioning system for vehicles. The heat exchanger constituted by laminating tube elements and fins alternately over a plurality of levels and in particular, the present invention relates to a laminated heat exchanger that adopts a structure in which a pair of tank portions are formed at one side of the tube elements and intake/outlet portions for heat exchanging medium are provided at one end in the direction of the lamination or at the end surface of the core main body in the direction of the air flow.
2. Description of the Related Art
In order to respond to the demand for miniaturization of heat exchangers and to improve the heat exchanging efficiency, applicant has developed the heat exchanger shown in
FIGS. 1 and 2
and has conducted much research related to this heat exchanger. In this laminated heat exchanger, a core main body is formed by laminating tube elements alternately with fins
2
over a plurality of levels, a pair of tank portions
12
provided at one side of each tube element are made to communicate via a U-shaped passage portion
13
, a heat exchanging medium flow passage with a plurality of passes is formed in the core main body by implementing communication between the tank portions
12
of adjacent tube elements as necessary, and intake/outlet portions (intake portion
4
and outlet portion
5
) for the heat exchanging medium are provided at one end of the core main body in the direction of the lamination with one of these intake/outlet portions (intake portion
4
) being made to communicate with a tank block
21
, which constitutes one end of the heat exchanging medium flow passage through a communicating pipe
30
and the other of the intake/outlet portions (outlet portion
5
) being made to communicate directly with a tank block
22
, which constitutes the other end of the heat exchanging medium flow passage.
The applicant has also been conducting various types of research into the one-side tank type laminated heat exchanger that is known in the prior art, as well as the heat exchanger described above. For instance, FIGS.
10
and
11
A-B show one such heat exchanger. In this heat exchanger, a core main body is formed by laminating tube elements alternately with fins
2
over a plurality of levels, a pair of tank portions
12
, provided at one side of each tube element (toward the bottom in the figures) are made to communicate via a U-shaped passage portion
13
and the tank portions
12
in adjacent tube elements are made to communicate as necessary to form a heat exchanging medium flow passage with a plurality of passes in the core main body. In these aspects, this heat exchanger is similar to the one described earlier. However, this heat exchanger is provided with intake/outlet portions (intake portion
4
, outlet portion
5
) for heat exchanging medium at the end surface of the core main body in the direction of the air flow.
In these heat exchangers described above, when the heat exchanging medium flows in through one of the intake/outlet portions (intake portion
4
), the heat exchanging medium enters the tank block
21
which constitutes one end of the heat exchanging medium flow passage either directly or via the communicating pipe
30
. After travelling through a plurality of passes, the heat exchanging medium reaches the tank block
22
, which constitutes the other end of the heat exchanging medium flow passage, and it flows out through the other of the intake/outlet portions (outlet portion
5
), which communicates with the tank block
22
. In this process, the flow of the heat exchanging medium, in which it travels upward or downward through the U-shaped passage portions
13
of the tube elements, is counted as one pass and, for instance, a heat exchanger in which the heat exchanging medium passes through the U-shaped passage portions
13
twice, starting from the tank block constituting one end of the heat exchanging medium flow passage until it reaches the tank block constituting the other end, is referred to as a 4-pass heat exchanger and if it passes through the U-shaped passage portions three times, it is referred to as a 6-pass heat exchanger.
However, in the first type of heat exchanger, i.e., in a 4-pass cooling heat exchanger, in which the heat exchanging medium passes through a tank group without a partitioning portion
18
when it moves from the second pass to the third pass, as shown in
FIG. 9A
, the coolant tends to flow in the direction that runs at a right angle to the air flow in the structure described above, in which the coolant flows out from one end of the core main body. This results in the coolant collecting in the tube elements close to the outlet (one end in the direction of the lamination). In other words, in the area extending from the third pass through the fourth pass, the coolant does not readily flow toward the side close to the partitioning portion
18
and this has been proved true through testing; the results of which are indicated with the broken lines in FIGS.
7
and
8
A-B, which demonstrate that the tube temperature and the passing air temperature in the area of the partitioning portion close to the outlet are higher than those in the other areas.
In this context, the tube temperature (TUBU TEMP.) refers to the temperature of the tube element itself and the tube numbers (TUBU No.) in
FIGS. 7 and 12
refer to the tube element numbers assigned starting from the front left side in
FIGS. 1 and 10
. Also, the passing air temperature (AIR TEMP.) refers to the temperature of the air that has passed through the area between the tube elements and for which heat exchange has been performed with the fins. The air temperature was measured at a position that is away from the end surface of the core main body on the downstream side by 1~2 cm.
In a 6-pass heat exchanger, too, the heat exchanging medium flow concentrates in the area toward the outlet side, away from the partitioning portion
18
, as shown in FIG.
9
B. As a result, it is assumed that the tube temperature and the passing air temperature in the area of the partitioning portion near the outlet will be different from those in the other areas.
Furthermore, in the latter type of heat exchanger, too, i.e., a 4-pass cooling heat exchanger, when the flow speed increases with the coolant flow rate per unit time increasing, the coolant will concentrate toward the end in the direction of the lamination when it moves from the second pass through the third pass, as shown in
FIG. 14
, and the coolant will not readily flow in the area toward the partitioning portion
18
in the area extending from the third pass through the fourth pass. The coolant is clearly demonstrated to flow in this manner by the test results indicated with the broken lines in
FIG. 12
, which show that the passing air temperature is higher in the area near the partitioning portion
18
compared to the other areas.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention is to provide a laminated heat exchanger in which heat exchanging medium can flow evenly throughout the tube elements without concentrating in any area and with which it is possible to achieve an improvement in heat exchanging efficiency.
The applicant has discovered that concentration of heat exchanging medium in any particular area can be prevented when the heat exchanging medium is made to flow sufficiently through the tube elements near the partitioning portion, which results in nearly consistent temperature distribution in the core main body, by changing the state of the flow of the heat exchanging medium travelling from an even-numbered pass to an odd-numbered pass in the tank group, and the applicant has completed the present invention based upon this observation.
In order to achieve the object described above, the laminated heat exchanger according to the present invention is constituted by laminating tube elements, each of which is provi
Inoue Seiji
Nishishita Kunihiko
Sakata Hitoshi
Tanda Kiyoshi
Atkinson Christopher
Wenderoth , Lind & Ponack, L.L.P.
Zexel Corporation
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