Heat exchange – Flow passages for two confined fluids – Interdigitated plural first and plural second fluid passages
Reexamination Certificate
1999-07-26
2002-04-23
Bennett, Henry (Department: 3743)
Heat exchange
Flow passages for two confined fluids
Interdigitated plural first and plural second fluid passages
C165S166000
Reexamination Certificate
active
06374910
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a heat exchanger including high-temperature fluid passages and low-temperature fluid passages defined alternately by alternately disposing a plurality of first heat-transfer plates and a plurality of second heat-transfer plates.
BACKGROUND ART
Such heat exchangers have already been proposed in Japanese Patent Application Nos.7-193208 and 8-275057 filed by the applicant of the present invention.
The above conventional heat exchangers suffer from the following problem: The partitioning between a high-temperature fluid passage inlet and a low-temperature fluid passage outlet and the partitioning between a low-temperature fluid passage inlet and a high-temperature fluid passage outlet are achieved by bonding a partition plate by brazing to a cut surface formed on the heat-transfer plate by cutting its angle-shaped apex portion. For this reason, the bonded portions of the cut surface of the heat-transfer plate and the partition plate are in line contact with each other. To reliably perform the brazing, the precise finishing of the cut surface is required, and moreover, even if the finishing is performed, it is still difficult to provide a sufficient bonding strength.
The above conventional heat exchangers also suffer from the following other problem: axially opposite ends of the heat-transfer plate are cut into angle shapes to define the fluid passage inlet and outlet. Therefore, a drifting flow of fluid is generated from the outer side toward the inner side as viewed in a turning direction due to a difference between the lengths of flow paths on the inner and outer sides as viewed in the turning direction in a region where a fluid flowing into the heat exchanger obliquely with respect to an axis in the vicinity of the fluid passage inlet is turned in the direction along the axis, and in a region where the fluid flowing in the direction along the axis is turned in an inclined direction with respect to the axis in the vicinity of the fluid passage outlet. For this reason, the flow rate on the outer side as viewed in the turning direction is decreased, while the flow rate on the inner side as viewed in the turning direction is increased, whereby the heat exchange efficiency is reduced due to the non-uniformity of the flow rate.
The above conventional heat exchanger is formed into an annular shape by folding a folding plate blank in a zigzag fashion to fabricate modules each having a center angle of 90° and combining four of the modules in a circumferential direction. However, if the heat exchanger is formed by combination of a plurality of modules, the following problems arise: the number of parts is increased, and moreover, four bonded points among the modules are produced, and the possibility of leakage of the fluid from the bonded portions is correspondingly increased.
DISCLOSURE OF THE INVENTION
The present invention has been accomplished with the above circumstances in view, and it is a first object of the present invention to ensure that a sufficient bonding strength is provided without a precise finishing of the ends of the heat-transfer plate. It is a second object of the present invention to suppress of a drifting flow of a fluid generated at fluid-direction changing portions in the vicinity of the fluid passage inlet and outlet of the heat exchanger thereby to prevent a reduction in heat exchange efficiency. It is a third object of the present invention to decrease the number of parts of the heat exchanger and to maintain the leakage of the fluid from the bonded portions of the folding plate blank to the minimum.
To achieve the above object, according to a first aspect and feature of the present invention, there is provided a heat exchanger, comprising a plurality of first heat-transfer plates and a plurality of second heat-transfer plates disposed radiately in an annular space defined between a radially outer peripheral wall and a radially inner peripheral wall, and a high-temperature fluid passage and a low-temperature fluid passage which are defined circumferentially alternately between adjacent ones of the first and second heat-transfer plates by bonding pluralities of projections formed on the first and second heat-transfer plates to one another, axially opposite ends of each of the first and second heat-transfer plates being cut into angle shapes each having two end edges, thereby defining a high-temperature fluid passage inlet by closing one of the two end edges and opening the other end edge at axially one end of the high-temperature fluid passage, defining a high-temperature fluid passage outlet by closing one of the two end edges and opening the other end edge at the axially other end of the high-temperature fluid passage, defining a low-temperature fluid passage outlet by opening one of the two end edges and closing the other end edge at axially one end of the low-temperature fluid passage, and defining a low-temperature fluid passage inlet by opening one of the two end edges and closing the other end edge at the axially other end of the low-temperature fluid passage, characterized in that flange portions formed by folding one of apex portions of the angle shape are superposed one on another and bonded together, whereby the high-temperature fluid passage inlet and the low-temperature fluid passage outlet are partitioned from each other by the superposed flange portions, and further flange portions formed by folding the other apex portion of the angle shape are superposed one on another and bonded together, whereby the high-temperature fluid passage outlet and the low-temperature fluid passage inlet are partitioned from each other by the superposed further flange portions.
With the above arrangement, in the annular heat exchanger in which the fluid passage inlets and outlets are defined by cutting the axially opposite ends of the heat-transfer plates into angle shapes, the flange portions formed by folding the apex portions of the angle shape are superposed one on another and bonded together, whereby the fluid passage inlet and outlet are partitioned from each other by bonding a partition plate to the superposed flange portions. Therefore, as compared with the case where a partition plate is bonded in a line contact state to the cut surfaces formed by cutting the heat-transfer plates, the superposed flange portions can be bonded together in a surface contact state, thereby not only increasing the bonding strength, but also eliminating the need for a precise finishing of the cut surfaces. Therefore, the bonding of the projections on the heat-transfer plates and the bonding of the flange portions can be accomplished in a continuous flow, leading to a reduction in processing cost.
If a folding plate blank including the first and second heat-transfer plates which are alternately connected together through first and second folding lines is folded in a zigzag fashion along the first and second folding lines, and portions corresponding to the first folding lines are bonded to the radially outer peripheral wall, while portions corresponding to the second folding lines are bonded to the radially inner peripheral wall, the number of parts can be reduced, and moreover, the misalignment of the first and second heat-transfer plates can be prevented to enhance the processing precision, as compared with the case where the first and second heat-transfer plates are formed from different materials and bonded to each other.
If the flange portions are folded into an arcuate shape and superposed one on another, and the height of projection stripes formed along angle-shaped end edges of the first and second heat-transfer plates is gradually decreased in the flange portions in order to close the fluid passage inlets and outlets, it is possible to prevent a gap from being produced between the projection stripes, while preventing the mutual interference of the projection stripes abutting against one another at the flange portions to enhance the sealability to the fluid.
To achieve the first object, according to a second aspect and f
Shikano Fumihiko
Tsunoda Tadashi
Wakayama Tokiyuki
Arent Fox Kintner Plotkin & Kahn
Bennett Henry
Duong Tho Van
Honda Giken Kogyo Kabushiki Kaisha
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