JP2735198B2 - Aluminum heat exchanger - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement of an aluminum heat exchanger. [Prior art] In a heat exchanger composed of a tank and a core, aluminum materials have recently been used as a material for manufacturing the heat exchanger for the purpose of reducing the weight of the body and simplifying the assembling work. It has become. FIG. 4 shows a conventional aluminum heat exchanger, and such an aluminum heat exchanger (hereinafter referred to as "heat exchanger").
First, a core 9 is temporarily assembled with an aluminum tube 3, a fin 5, and a seat plate 7 clad with a zinc-containing brazing material, and aluminum rain hoses 11 are provided on both sides of the core 9. And apply a flux of fluoride to them. Also, in order to prevent the core 9 assembled temporarily from being decomposed, a wire or a baking jig is used to connect the core 9 to the rain hose.
Uniting 11 Next, the core 9 and the rain hose were placed in a brazing furnace and maintained at a brazing temperature of 580 to 620 ° C. for 3 to 20 minutes while pumping nitrogen gas at a rate of 30 to 40 m ³ / hr into the furnace.
11 is brazed together. And after the brazing process,
Upper tank 13 and lower tank made of resin
15 are each installed with watertightness to make them products. Conventionally, the tube 3 and the rain hose 11 have A3
The same material such as 003 aluminum material is used. In the drawing, reference numeral 11 'denotes reinforcing pieces formed on both sides of the rain hose 11. The reinforcing piece 11 'has a length equal to that between the seat plates 7,7. [Problems to be Solved by the Invention] However, aluminum has an extremely large linear expansion coefficient as compared with brass or copper, and as described above, the conventional heat exchanger 1 is a member having a remarkable temperature rise like the tube 3. Since the member having a not so large temperature rise such as the rain hose 11 is formed of an aluminum material having the same linear expansion coefficient, the thermal expansion of the tube 3 with the rain hose 11 at the time of high temperature of the cooling water such as when the vehicle is running. There is a possibility that a strain based on the difference in the rate is generated, and the thin tube 3 is finally broken due to the thermal strain stress. That is, the tube 3 is significantly heated by the high-temperature cooling water as compared with the rain hose 11, and tends to generate a large thermal expansion. However, the heat transmission from the cooling water is small, and the thermal expansion of the tube 3 is small. The maximum temperature difference between the tube 3 and the rain hose 11 is about 50 ° C. Therefore, since the seat plate 7 and the rain hose 11, and the tube 3 and the seat plate 7 are integrally brazed, respectively, of the tubes 3 to be thermally expanded, especially the tube 3 'adjacent to the rain hose 11 is used. The expansion is hindered by the rain hose 11 having a small thermal expansion, and distortion is generated. As a result, "permanent distortion due to compression" is generated by the rain hose 11 at the base of the tube 3 'with the seat plate 7. Then, the tube 3 'shrinks due to a decrease in the temperature of the cooling water due to a subsequent engine stop or the like, and a tensile stress is applied to the root portion where permanent deformation has occurred, so that the thin-walled tube 3' is finally broken. . FIG. 5 shows the stress value applied to the tube 3 by an experiment. As described above, the stress is concentrated most at the root of the tube 3 ′ adjacent to the rain hose 11, and the stress value is increased at the other tubes 3. It can be seen that it is reduced. Further, the problem of "permanent set due to compression" is raised as a problem to be solved even when the core 9 is baked.
That is, at the time of baking, the core 9 is greatly deformed to both sides due to thermal expansion as shown in FIG. 6, but at this time, the tubes 3, 3 'are prevented from being stretched by the rain hose 11, so that distortion occurs. As a result, a "permanent set due to compression" by the rain hose 11 is formed at the root of the tube 3 'with the seat plate 7.
Had occurred. Then, as a solution to such a problem, the mounting material of the radiator is divided into an upper mounting material and a lower mounting material, and the upper mounting material is welded to the side surface and the fin of the upper tank,
A mounting structure of an aluminum radiator in which a lower mounting member is welded to a side surface and a fin of a lower tank is disclosed in Japanese Utility Model Publication No. 46-27719. However, when the mounting material is divided in this manner, rigidity at the time of core bundling by a wire or the like necessary for integral brazing cannot be secured. In addition, after brazing rain hoses integrally on both sides of the core, each rain hose is cut and divided into upper and lower parts, but fins protrude from the cut surface of the rain hose or the rain hose is cut. In many cases, the fins were cut by passing through the fins, which led to a decrease in the commercial value of the heat exchanger. [Purpose of the Invention] The present invention has been devised in view of such circumstances, and increases the rigidity of the rain hose at the time of bundling the core necessary for brazing processing, and at the same time, prevents tube breakage due to thermal strain stress. It is an object to provide a heat exchanger that is prevented. [Means for Solving the Problems] In order to achieve such an object, the present invention provides a reinforcing piece having the same length as the space between the seat plates on both sides of a core comprising a tube, a fin, and a seat plate. In a heat exchanger made of aluminum, a rain hose having a U-shaped cross-section and having the ends thereof in contact with the seat plate and brazing them together is provided. At least one portion of the hose is cut inward except for the outer ends of the reinforcing pieces facing each other, and a weak portion that is weaker than the tensile strength of the adjacent tube is formed in the rain hose. According to the present invention, each outer end of the reinforcing piece secures the rigidity of the rain hose required for binding the core during integral brazing, and the temperature change of the cooling water during running of the vehicle. When the core is baked, the fragile portion of the rain hose is stretched, shrunk or cut in accordance with the stretching or shrinking of the tube, thereby reducing the compressive stress applied to the root of the tube. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Since the configuration except for the invention is the same as that shown in FIG. 4, the description thereof will be omitted here, and the invention will be described exclusively. or,
The same elements as those in the above-described conventional example are denoted by the same reference numerals. FIG. 1 shows an embodiment of the heat exchanger according to the present invention. This heat exchanger 17 is, like the heat exchanger 1, a rain hose 19 having a U-shaped cross section attached to both sides of the core 9 as a tube 3. ,
Although it is made of the same aluminum material as 3 ', in this embodiment, a substantially central portion of the rain hose 19 is cut inward except for the outer end portion 19 "of each reinforcing piece 19' facing each other. hand,
A fragile portion 21 whose minimum cross-sectional area is smaller than the cross-sectional area of each adjacent tube 3 'and weaker than the tensile strength of the tube 3' is formed in the rain hose 19. It should be noted that if the rain hose 19 is cut out to provide the fragile portion 21 after the core 9 is integrally brazed, there is a possibility that the fin 5 may be cut off. It must be provided before brazing. FIG. 2 is a cross-sectional view of FIG.
FIG. 3 is a sectional view taken along line II-II of FIG. 1, and FIG. 3 is a sectional view of the fragile portion 21. Thus, in the heat exchanger 17 according to the present embodiment, as in the conventional example shown in FIG. 4, after the core 9 and the rain hose 19 are integrally brazed, the upper tank 13 and the lower tank 15 are attached to the seat plate 7. Good. Since the heat exchanger 17 according to the present embodiment is configured as described above, each of the outer end portions 19 ″ of the fragile portion 21 is required to be bundled with the rain hose 19 when the core 9 is bound by a wire or the like when brazing is performed integrally.
When the tubes 3, 3 'expand and contract due to the temperature change of the cooling water during running of the vehicle or the baking of the core 9, the heat transfer from the cooling water to the rain hose 19 is small. The fragile portion 21 of the rain hose 19 is extended, contracted, or cut in accordance with the extension and contraction of the tube 3, so that the compressive stress applied to the root portion of the tube 3 'is reduced. As described above, according to the present embodiment, each outer end 19 ″ of the fragile portion 21 secures the rigidity of the rain hose 19 necessary for binding the core 9 with a wire or the like in the brazing process.
The strength at the time of core bundling is improved, and there is an advantage that the commercial value is maintained without cutting the fins 5 as compared with the conventional example in which the brazed rain hose is cut and divided into two. Further, according to the present embodiment, since the amount of thermal strain applied to the base of the tube 3 'is significantly reduced, the "permanent set due to compression" by the rain hose 19 at the base of the tube 3' is reduced. The function of the heat exchanger was maintained well over a long period of time. In the above embodiment, the fragile portion 21 is provided at one location in the center of the rain hose 19. However, the fragile portion 21 may be provided at a plurality of locations, and the intended purpose is achieved by such a structure. It is possible. Further, in the above embodiment, when the tubes 3, 3 'and the rain hose 19 are formed of an aluminum material having the same linear expansion coefficient, the cross-sectional area of the tube 3' having a substantially central portion of the rain hose 19 is obtained. Although the fragile portion 21 that is weaker than the tensile strength of the tube 3 'is formed in the rain hose 19 by forming the tube to be smaller, even when the tube and the rain hose are aluminum materials having different linear expansion coefficients, With the structure described above, the rain hose may be provided with a fragile portion weaker than the tensile strength of the tube. [Effects of the Invention] As described above, the present invention has a U-shaped cross section provided with reinforcing pieces having the same length as the space between the seat plates on both sides of the core including the tube, the fins, and the seat plate. In an aluminum heat exchanger in which a rain hose is provided and each end of the rain hose is brought into contact with the seat plate and brazed together, at least one of the rain hoses is opposed to each other. The outer ends of the reinforcing pieces to be cut are cut inward leaving the outer ends of the reinforcing pieces to be weakened, and a weak portion that is weaker than the tensile strength of the adjacent tube is formed in the rain hose. The rigidity of the rain hose required for binding the core at the time was secured, and as a result, the yield of the core was improved. Further, since the fragile portion of the rain hose is extended, contracted or cut in accordance with the extension and contraction of the tube, the compressive stress applied to the base of the tube is reduced, and cracks may be generated at the base of the tube. As a result, the reliable function of the heat exchanger was maintained for a long time.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of a heat exchanger according to one embodiment of the present invention. FIG. 2 is a sectional view taken along line II of FIG. FIG. 3 is a cross-sectional view taken along the line II-II of FIG. FIG. 4 is a perspective view of a conventional heat exchanger. FIG. 5 is an explanatory diagram showing stress values applied to tubes of a conventional heat exchanger. FIG. 6 is a schematic view showing a deformed state at the time of core burning. [Explanation of Signs of Main Parts] 3,3 'Tube 5 Fin 7 Seat 9 Core 17 Heat exchanger 19 Rain hose 19' Reinforcing piece 19 " Outer end 21 ... a fragile part.

Claims (1)

(57) [Claims] On both sides of a core consisting of a tube, fins and a seat plate, a rain hose having a U-shaped cross section provided with a reinforcing piece having a length equal to the distance between the seat plates is arranged, and each end of the rain hose is connected to the above. In an aluminum heat exchanger made by abutting the seat plate and brazing them integrally, at least one portion of each of the above-mentioned rain hoses is cut inward while leaving each outer end of the reinforcing piece facing each other. A heat exchanger made of aluminum, wherein a weak portion that is weaker than the tensile strength of the facing tube is formed in the rain hose.