Header plateless heat exchanger

Abstract

With respect to a header plateless heat exchanger having as a component a flat tube formed by joining a pair of grooved plates together, air-tightness and liquid-tightness are improved between the portion of the flat tube where the plates are joined together and a header tank. A flat tube is formed by folding tab parts extending from side walls of a first plate back outwards to lie over the outer surfaces of those side walls of the first plate, and placing seating portions of side walls of a second plate on the upper end surfaces of the tab parts, after which a header tank is fitted on each longitudinal end of the flat tube.

Claims

1. A header plateless heat exchanger, comprising a first plate and a second plate each bent and formed into a groove shape by press forming, the plates respectively including side walls each having a height on each longitudinal end of the plate higher than a height at a midpoint portion of the plate, the first plate and the second plate being joined with each other at the side walls to form a flat tube having a bulging portion in a height direction on longitudinal end of the flat tube, a plurality of the flat tubes stacked at the bulging portion to form a core, and a casing fitted over an outer periphery of the core and a header tank and disposed at both ends of the core, wherein tab parts located at the bulging portion and disposed so as to extend from the side walls of the first plate are folded back to lie over outer surfaces of the side walls of the first plate, and lower end surfaces of the side walls of the second plate are seated on upper end surfaces of the tab parts, and lower end surfaces of the tab parts conform to an outer surface of a groove bottom of the first plate.

2. The header plateless heat exchanger according to claim 1, wherein a lower end portion of the tab part in a height direction is cut out at a folding-back position to form a cut-out portion at the position, thus facilitating folding back at the end portion.

3. The header plateless heat exchanger according to claim 1, wherein a recessed portion or a claw is provided by striking in a thickness direction, located on the lower edge of the tab part to partially fill, with the recessed portion or the claw, a gap between the outer surface of the side wall of the first plate and an inner surface of the tab part.

4. The header plateless heat exchanger according to claim 1, wherein a protruding portion is provided downward on the lower end surfaces of the tab part to partially fill a gap between the tab part and a member located below the first plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is an exploded perspective view illustrating a main portion of a flat tube 5 of a header plateless heat exchanger of the present invention.

(2) FIG. 2 is an enlarged view of a portion II in FIG. 1.

(3) FIG. 3 is a perspective view illustrating a main portion of an assembly of the same flat tube 5.

(4) FIG. 4 is a traverse cross section of a core 6, taken at a position IV-IV in FIG. 3, including a stacked body of the same flat tubes 5.

(5) FIG. 5 is a perspective view illustrating a main portion of a first plate 1 used in Example 2 of the present invention.

(6) FIG. 6 is a side view illustrating a main portion of the same flat tube 5.

(7) FIG. 7 is a perspective view illustrating a main portion of a first plate 1 used in Example 3 of the present invention.

(8) FIG. 8 is a side view illustrating a main portion of a flat tube 5 used in a fourth Example 4 of the present invention.

(9) FIG. 9 is a perspective view illustrating a main portion of a first plate 1 used in the same example.

(10) FIG. 10 is a perspective view illustrating a main portion of a first plate 1 used in Example 5 of the present invention.

(11) FIG. 11 is a diagram illustrating an operation in the same example, and is an explanatory view illustrating a case where the round of the corner of tab part 9 is large.

(12) FIG. 12 is a diagram illustrating operation in the same example, and is an explanatory view illustrating a case where the round of the corner of the tab part 9 is small.

(13) FIG. 13 is a traverse sectional view illustrating main portions of a header plateless heat exchanger of a conventional example.

DETAILED DESCRIPTION OF THE INVENTION

(14) (Basic Structure of Heat Exchanger)

(15) This header plateless heat exchanger is used, for example, as EGR cooler or a condenser, in which, gas is introduced into a header tank 8 side; the introduced, gas passes within flat tubes 5; cooling water flows into an area surrounded by the outside of the flat tubes 5 and a casing 7; and heat exchange is performed between the gas and the cooling water.

(16) This heat exchanger includes a core 6 formed by stacking, at bulging portions 4, flat tubes 5 having both ends bulging in the thickness direction, and does not require any header plate. In addition, a pair of header tanks 8 are fitted over both ends of the core 6 in the longitudinal direction as illustrated in FIG. 4. Moreover, in this example, the casing 7 is fitted over the outer periphery of the core 6 through an opening of the header tank 8. For example, the casing 7 includes a casing body formed into a C-shape in cross section, and an end lid that closes the opening thereof, and the entire casing 7 is formed into a cylindrical shape. The casing body has inlet and outlet, which form a pair, for cooling water, and a pair of pipes are connected thereto.

(17) It should be noted that, in this example, the header tank 8 is fitted over both ends of the core 6, and the casing 7 is fitted over the outside of the header tank 8. However, instead of the configuration, the casing 7 may be fitted over the core 6, and the header tank 8 may be fitted over the outside of the casing 7. In the case also, the header tank 8 is disposed on both ends of the core 6, which is the configuration described above as the first aspect of the invention.

(18) In addition, the casing and the header tank may be integrally formed. Even in the case, the header tank 8 is disposed on both ends of the core 6, which is the configuration described above as the first aspect of the invention.

(19) Members used to manufacture the header plateless heat exchangers are obtained by press forming metal plates (aluminum, aluminum alloy, steel plates, and the like), with brazing materials covering or being applied to at least one side of the surface layer thereof. Respective parts are assembled together, and then, are integrally brazed in a furnace at high temperatures.

EXAMPLE 1

(20) Hereinbelow, the embodiments of the present invention will be described with reference to the drawings.

(21) FIGS. 1 to 4 illustrate Example 1 of the present invention.

(22) A flat tube 5 used in the present invention includes a joined body of a first plate 1 and a second plate 2, which are a pair of upper and lower plates each formed into a groove shape; both end portions of each of the plates 1 and 2 in the longitudinal direction are expanded and opened in the thickness direction; and a bulging portion 4 is formed there.

(23) As illustrated in FIG. 1, the inner surfaces of side walls 2a of the second plate 2 are fitted over the outer surfaces of a pair of side walls la of the first plate 1. In addition, the tab parts 9 are integrally formed so as to extend through a folded portion 9b, on the side wall (1a) of each of the both end portions of the first plate 1 in the longitudinal direction. The tab part 9 is folded back outward, and is overlapped on the outer surface of the side wall la of the first plate 1, and the upper end surface 9a of the tab part 9 forms a sitting surface 15. The sitting surface 15 corresponds to the stepped portion 10 (see FIG. 13) of the conventional-type flat tube, and a seating portion 2c of the side wall 2a of the second plate 2 sits thereon. Furthermore, the lower end surface 9c of the tab part 9 is aligned to match the outer surface of the groove bottom 1b at the bulging portion 4 of the first plate 1 as illustrated in FIG. 4.

(24) In this example, a cut-out portion 11 is provided at the lower end portion of the folded portion 9b, facilitating folding back of the tab parts 9. In addition, as illustrated in FIGS. 1 and 3, by cutting out the seating portion 2c of the second plate 2 into a shape that matches the sitting surface 15 of the tab part 9, it is possible to easily position both of the plates 1 and 2.

(25) The flat traces 5 configured as described above are stacked at the positions of the bulging portions 4 to form the core 6, and the opening of the header tank 8 is fitted over both end portions in the longitudinal direction, whereby giving a state illustrated in FIG. 4.

(26) As illustrated in FIG. 4, the tab part 9 has the upper end surface 9a and the lower end surface 9c both formed into a right angle, and hence, it is possible to achieve tight contact with the inner peripheral surface of the header tank 8 over the entire length of the tab part 9 in the height direction without any gap. In addition, the outer surface of the side wall 2a of the second plate 2, with which the upper end surface 9a is joined together, also tightly contacts with the inner peripheral surface of the header tank 8 over substantially the entire length, except for the corner portion with the groove bottom 2b. Thus, it is possible to reduce a portion suffered from the loss of brazing as much as possible at the time of brazing each part, and hence, it is possible to improve air-tightness and liquid-tightness around the header tank 8 of the heat exchanger.

EXAMPLE 2

(27) FIGS. 5 and 6 illustrate Example 2 of the present invention.

(28) This example differs from Example 1 in that a recessed portion 12 is provided at the lower end portion of the tab part 9 in a direction of the side wall 1a of the first plate 1. This recessed portion 12 is provided, by striking, at a part of the lower end portion of the tab part 9 (in the vicinity of the opening of the flat tube 5 in this example) in the thickness direction, as illustrated in FIG. 5.

(29) With this configuration, the gap between the R portion of the first plate 1 and the tab part 9 can be partially filled as illustrated in FIG. 6, so that the loss of brazing can be further prevented as much as possible.

EXAMPLE 3

(30) FIG. 7 illustrates Example 3 of the present invention.

(31) This example differs from Example 2 in that a claw 13 folded into a plane triangle is provided in place of the recessed portion 12 of the tab part 9. In this example also, it is possible to obtain an effect similar to that of Example 2.

(32) In Example 2 and Example 3, the outer surface of the tab part 9 is brought into close contact with the inner peripheral surface of the header tank 8 except for the portion where the recessed portion 12 or claw 13 is formed, and hence, there is no possibility that air-tightness or liquid-tightness deteriorates.

EXAMPLE 4

(33) FIGS. 8 and 9 illustrate Example 4 of the present invention.

(34) This example differs from Example 2 or Example 3 described above in that a protruding portion 14 that is provided so as to protrude downward is provided on the lower end surface 9c of the tab part 9. FIG. 8 is an explanatory view illustrating a case where the core 6 is formed with the flat tubes 5.

(35) It is possible to partially fill a gap+between the tab part 9 and a member (the second plate 2 of the flat tube 5 or the lower portion of the inner periphery of the header tank 8) located below the first plate 1, in particular, a gap having a triangle shape formed by the header tank 8, the corner portion of the second plate 2, and the tab part 9 of the first plate 1.

(36) However, in the case of this shape, interference occurs between the corner portion of the second plate 2 and the protruding portion 14 of the tab part 9, and pushes up, by an amount of , the corner portion 9d of the tab part 9 with the folded portion 9b being the fulcrum as illustrated in FIG. 12, possibly causing misalignment of the joining portion with the second plate 2.

(37) To solve this problem, the protruding portion 14, which is provided on the tab part 9, is provided at a position farthest from the opening end of the bulging portion 4, and the corner portion 9d, which faces the position, is provided to have a large round shape as illustrated in FIG. 11, whereby the amount of push-up is reduced.

EXAMPLE 5

(38) FIGS. 10 to 12 illustrate Example 5 of the present invention, in which the recessed portion 12 is added to the example of FIG. 9 to fill the triangle gap inside the tab part 9 of FIG. 8.