Heat exchanger

Details Heat exchanger Heat exchanger

1999-04-06

2001-04-17

Lazarus, Ira S. (Department: 3743)

Heat exchange

Flow passages for two confined fluids

Interdigitated plural first and plural second fluid passages

C165S166000

Reexamination Certificate

active

06216774

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to an annular-shaped heat exchanger including high-temperature fluid passages and low-temperature fluid passages defined alternately by folding a plurality of first heat-transfer plates and a plurality of second heat-transfer plates in a zigzag fashion.
BACKGROUND ART
Such heat exchanger is known from Japanese Patent Application Laid-open No.57-2983. There is also a heat exchanger known from Japanese Patent Application Laid-open No.59-183296, which includes high-temperature fluid passages and low-temperature fluid passages defined alternately between heat-transfer plates disposed in parallel, and outlets and inlets for a high-temperature fluid and a low-temperature fluid, which are defined by cutting opposite ends of each of the heat-transfer plates into angle shapes.
When ducts are connected to the high-temperature fluid passages and the low-temperature fluid passages in a heat exchanger made of a metal, it is necessary to bond ends of a partition plate forming the duct to the heat-transfer plates of the heat exchanger by brazing. The heat exchanger in which the opposite ends of each of the heat-transfer plates are cut into the angle shape, as described in the above Japanese Patent Application Laid-open No.59-183296, suffers from the following problem: The material yield for the heat-transfer plates is naturally poor, and it is necessary to braze the partition plate to the apex of the end surface resulting from the cutting into the angle shape. For this reason, it is difficult to carry out the brazing operation because of a small brazing area, and moreover, it is difficult to provide a sufficient brazing strength.
DISCLOSURE OF THE INVENTION
The present invention has been accomplished with the above circumstances in view, and it is an object of the present invention to provide a heat exchanger in which a good material yield is provided and moreover, it is easy to carry out the brazing of a member for forming a fluid duct.
To achieve the above object, according to an aspect and feature of the present invention, there is provided a heat exchanger which is formed from a folding plate blank comprising a plurality of first quadrilateral heat-transfer plates and a plurality of second quadrilateral heat-transfer plates which are alternately connected together through first and second folding lines, the folding plate blank being folded in a zigzag fashion along the first and second folding lines, thereby defining axially extending high-temperature and low-temperature fluid passages alternately in a circumferential direction, radially outer peripheral walls are brazed to the plurality of first folding lines located on a radially outer side and radially inner peripheral walls are brazed to the plurality of second folding lines located on a radially inner side, thereby closing radially outer and inner peripheries of the axially extending high-temperature and low-temperature fluid passages, while defining high-temperature fluid ducts connected to the high-temperature fluid passages and low-temperature fluid ducts connected to the low-temperature fluid passages; a high-temperature fluid passage inlet and a high-temperature fluid passage outlet are formed in openings at axially opposite ends of the high-temperature fluid passages; and projection stripes provided on the first and second heat-transfer plates are brazed to one another, thereby closing axially opposite ends of the low-temperature fluid passages, while defining a low-temperature fluid passage inlet in one of the radially outer and inner peripheral walls on the side of the high-temperature fluid passage outlet, and a low-temperature fluid passage outlet on the other of the radially outer and inner peripheral walls on the side of the high-temperature fluid passage inlet.
With the above arrangement, the radially outer peripheral walls are brazed to the plurality of first folding lines located on the radially outer side and the radially inner peripheral walls are brazed to the plurality of second folding lines located on the radially inner side in order to define the high-temperature fluid ducts connected to the high-temperature fluid passages and the low-temperature fluid ducts connected to the low-temperature fluid passages. Therefore, it is unnecessary to carry out a special working treatment in order to form brazed portions on the first and second heat-transfer plates, leading not only to a reduced number of working steps, but also to an increased brazing strength, as compared with the case where the first and second heat-transfer plates are brazed to the cut end surfaces.
In addition, the high-temperature fluid passage inlet and the high-temperature fluid passage outlet are defined in the openings at the axially opposite ends of the high-temperature fluid passages, and the projection stripes provided on the first and second heat-transfer plates are brazed to one another to close the axially opposite ends of the low-temperature fluid passages, while defining the low-temperature fluid passage inlet in one of the radially outer and inner peripheral walls on the side of the high-temperature fluid passage outlet, and the low-temperature fluid passage outlet on the other of the radially outer and inner peripheral walls on the side of the high-temperature fluid passage inlet. Therefore, even if the first and second heat-transfer plates are formed into a simple quadrilateral shape to enhance the material yield, the outlets and inlets for a high-temperature fluid and a low-temperature fluid can be defined. Moreover, the projection stripes are used for closing the opposite ends of the low-temperature fluid passages and hence, it is unnecessary to provide flaps in a projecting manner on the first and second heat-transfer plates in place of the projection stripes, whereby the material yield can be further enhanced.


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