JPH04284933A - Manufacture of oil cooler for automobile - Google Patents

Abstract

PURPOSE:To stop the leakage of oil distribution tube and to reduce the pressure drop of fluid. CONSTITUTION:A straight tubular tube 12 made of aluminum which parallel- shaped projection 23 which is extended in the longitudinal direction of tube are formed on the inside surface is used. A U-shaped tube 12 is formed by bending the straight tubular tube 12. Before or after bending the straight tubular tube 12, the projection 23 in the end part of the tube 12 are removed. Small diameter part 22 for joining piping is formed at that end part by contracting that end part so that the inside diameter D1 of that end part is approximately equal to the diameter D2 of the virtual circle that is in contact with the tips of the projection 23 in the other part excepting that end part.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an air-cooled oil cooler used in a hydraulic power steering system for an automobile.

0002

2. Description of the Related Art In this type of manufacturing method, as shown in FIG. It is known that a U-shaped tube section 54 is inserted and welded across the other ends of the two central tube sections 53 to obtain an oil cooler entirely made of iron.

0003

SUMMARY OF THE INVENTION This type of oil cooler is installed in a place with a poor environment, such as under a radiator of an automobile. Therefore, the oil cooler must be durable, and in this respect, an oil cooler made entirely of iron is advantageous. However, iron oil coolers are heavy and have poor heat exchange efficiency. In addition, three types of pipe sections must be welded together, and workability is poor, which complicates the manufacturing process. In addition, there is a risk of leakage from the welded portion, resulting in poor reliability.

[0004] Furthermore, there is a small diameter section at the end of the tube for piping connection, and the cross-sectional area of the passage changes rapidly between the small diameter section and other sections, resulting in a large pressure loss of the fluid and further deteriorating the heat exchange efficiency. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing an oil cooler for an automobile that solves the above-mentioned problems.

[0005]

[Means for Solving the Problems] A method of manufacturing an oil cooler for an automobile according to the present invention uses a straight aluminum tube having parallel protrusions extending in the length direction of the tube on its inner surface. By bending,
Diameter of an imaginary circle where a U-shaped tube is formed and the protrusion at the end of the tube is removed before or after bending the straight tube, and the inner diameter of the same end touches the tips of the protrusions other than the same end. This feature is characterized in that a small diameter portion for connecting piping is formed at the same end by constricting the same end so that the diameter is approximately equal to the diameter of the pipe.

[0006]

[Operation] The method for manufacturing an automotive oil cooler according to the present invention uses a straight aluminum tube having parallel protrusions extending in the length direction of the tube on its inner surface.
Since the U-shaped tube is formed by bending a straight tube, the entire tube is made of one pipe, and no welding work is required to manufacture the tube.

[0007] Also, before or after bending a straight tube, the protrusions at the end of the tube are removed so that the inner diameter of the same end is approximately equal to the diameter of an imaginary circle touching the tips of the protrusions other than the same end. By narrowing the same end so that the small diameter part for connecting the pipe is formed at the same end, there is relatively little change in the passage cross-sectional area between the small diameter part and other parts.

[0008]

Embodiments An embodiment of the present invention will now be described with reference to FIGS. 1 to 11.

As shown in FIG. 4, the oil cooler obtained by the method according to the present invention is made entirely of aluminum or an alloy thereof, and has a U-shaped shape having straight pipe portions 11 extending parallel to each other. shaped oil distribution tube 12
It consists of a large number of parallel plate fins 13 which are secured to the outer surfaces of both straight pipe parts 11, and two inner fins 15 which are respectively inserted into both straight pipe parts 11.

[0010] A small diameter portion 22 for connecting pipes is formed at the distal end portions of both straight pipe portions 11 via a tapered portion 21 . As shown in FIGS. 5 to 8, a large number of protrusions 23 are formed in parallel on the inner surface of the tube 12, excluding the small diameter portion 21, extending in the length direction of the tube. These protrusions 23 increase the heat transfer area and promote the generation of turbulence. The protrusion 23 exists in the tapered portion 21, but does not exist in the small diameter portion 22, as shown in FIG. Moreover, as shown in FIG. 9, if protrusions 24 and 25 of different heights are formed in place of the protrusion 23, the generation of turbulent flow will be further promoted. Furthermore, twisting the protrusions 24 and 25 is effective in generating turbulent flow. It is preferable that the twist angle θ is about 6 to 8 degrees. .

Referring to FIG. 1, the inner diameter D1 of the small diameter portion 21
is approximately equal to the diameter D2 of the imaginary circle touching the tip of the protrusion 23 other than the small diameter portion 21, so that oil can smoothly flow in and out of the tube 12.The plate fin 13 shown in FIG. It is shaped like an oval. Two tube insertion holes 31 that match the outer surface of the straight tube portion 11 are formed in the fin 13 at a pitch equal to the pitch of both straight tube portions 11 in the fin length direction. A flange 32 is formed at the edge of the tube insertion hole 31, and projections 33 are formed at four locations at the tip of the flange 32.

[0012] The inner fin 15 is a band-shaped member made of an aluminum brazing sheet, and is spirally twisted. In some cases, the inner fin 15 may be omitted.

Referring again to FIG. 4, there is a finless portion near the tip of both straight tube portions 11, and the mounting bracket 41 is attached with bolts across these portions, and the length of both straight tube portions 11 is There is also a finless portion in the middle, and the mounting bracket 42 is attached with bolts across this portion.

Next, three embodiments of a method for manufacturing an oil cooler will be described in detail with reference to FIG.

<Example 1> As the tube material, A110
0 aluminum alloy is used.

Then, the separately formed inner fins 15 are inserted into the tube 12, and the protrusions 23 at the portions that will become the small diameter portions 22 at both ends of the tube are cut and removed. If the protruding strip 23 exists, it becomes a hindrance, and the end portion which is to become the small diameter portion 22 in the next step cannot be narrowed properly.

Furthermore, when removing the protrusion 23, the protrusion 23
Instead of removing all of the protrusions 23, the base portion 23a of the protrusion 23 may be left as shown in FIG. 3(a). In this way, as shown in Fig. 3(b), the small diameter portion 22 is removed in the subsequent process.
After forming, the base 23a of the remaining protrusion 23 allows
The pressure resistance of the small diameter portion 22 is improved, and piping becomes easier. Also in this case, the inner diameter D3 of the small diameter portion 22 is
It is preferable that the diameter D4 is approximately equal to the diameter D4 of the virtual circle that is in contact with the tip of the other protrusion 23.

[0018] Also, instead of cutting and removing the protrusion 23,
The protrusion 23 may be plastically deformed to eliminate the protrusion 23. By doing so, generation of burrs etc. during cutting can be prevented. If burrs or the like enter the hydraulic circuit and clog it, it will interfere with steering wheel operation.

Next, by drawing both ends of the tube 12, a tapered portion 21 and a small diameter portion 22 are formed at both ends of the tube 12. In this way, the straight tube 12 is made into a U-shaped tube 12 by bending.

[0020] As the plate fin material, JISA11
00 aluminum alloy is used. Molding of the fins 13 and machining of the tube insertion hole 31 are carried out by conventional means, although they will not be described in detail.

Next, each 2 of all the fins 13
Both straight tube portions 11 of the U-shaped tube 12 are inserted into the respective tube insertion holes 31. In this case, since the tube 12 does not have a soldered part, the fin 13 will not be caught in the soldered part, and the tube 12 will be smoothly inserted while being guided by the tapered part 21. Therefore, the clearance between the tube 12 and the fins 13 is small, and brazing properties are particularly good without the need for pipe expansion work. Also, fin 13
Since it is oval, there is no risk of injury to the operator's hands. Then, the fins 13 were arranged so that adjacent ones were in contact with each other, and the thus assembled tube 12 and fins 13 were joined by a zinc chloride reaction brazing method.

[0022] Since no welding work is required to form the tube 12, a highly reliable oil cooler with no fear of leakage from the soldered parts can be obtained.

Furthermore, since the fins 13 span both straight pipe portions 11 of the tube 12, the tube 12 and the fins 13 are mutually reinforced, thereby providing an oil cooler with excellent strength.

<Example 2> A tube 12 is formed by extruding an aluminum alloy. Aluminum alloy contains 0.3-0.7% manganese and 0.1-0.5% copper
The remainder consists of aluminum and unavoidable impurities. Unavoidable impurities are 0.2% or less of silicon, 0.5% or less of iron, 0.05% or less of chromium, 0.1% or less of zinc, and 0.05% or less of titanium. Projections 2 on the inner surface of the tube 12
3 is formed during extrusion. The reason for using the above aluminum alloy is that it has extremely good extrusion processability. A brazing sheet is used as the plate fin material. The core material of the brazing sheet is silicone-free.
．． 6% or less, iron 0.5% or less, copper 0.05% or less, manganese 1.0-1.5%, magnesium 0.05% or less,
It consists of 0.04-0.12% chromium, 0.1% or less zinc, 0.06% titanium, 0.04-0.10% indium, and the balance aluminum. The skin material of the brazing sheet contains 6.8 to 11.0% silicon, 0.8% or less iron, 0.25% or less copper, 0.10% or less manganese, 0.6 to 2.3% magnesium, and 0 chromium. .10% or less, zinc 0.
20% or less, titanium 0.10% or less, bismuth 0.13
% or less and the balance consists of aluminum.

As in Example 1, the tubes 12 and fins 13 were assembled, placed in a vacuum furnace and heated, and the tubes 12 and fins 13 were joined to obtain an oil cooler.

According to the above method, the extrusion processability of the tube 12 is good, the electric potential of the tube 12 obtained is noble, and the strength is high. Therefore, the tube 12 with excellent corrosion resistance and strength can be obtained. can get.

In addition, since the potential of the tube 12 is high and the potential difference between the tube 12 and the fin 13 is large, the fin 13 undergoes sacrificial corrosion.
2. Corrosion is prevented and an oil cooler with excellent durability can be obtained.

<Example 3> As the tube material, JISA
An extruded pipe made of 1100 aluminum alloy is used.

A brazing sheet is used as the plate fin material. The core material of the brazing sheet is JISA
It is an aluminum alloy made of 3003, and its skin material is 6.3 to 10.0% silicon, 0.8% or less iron, and 0.2% copper.
5% or less, magnesium 0.06% or less, chromium 0.0
It is an aluminum alloy containing 5% or less of zinc and 2.25% or less of zinc, with the balance being aluminum.

As in both of the above embodiments, the tube 12 and fin 13 are assembled and brazed using fluoride flux. During brazing, as shown in FIG.
A zinc layer 45 having a thickness of m2 is precipitated, but this is not limited to thermal spraying, and may be done by plating or coating. and,
The tube 12 and fin 13 are brazed by heating the combination of the tube 12 and fin 13 at a temperature of about 600° C. in a heating furnace in an inert gas atmosphere. Due to this heating effect, the zinc layer 45 forms a zinc diffusion layer 46 on the outer surface of the tube 12, and the depth T thereof is preferably suppressed to 200 μm or less. If it exceeds this range, the strength of the tube 12 will decrease and pitting corrosion will likely occur. Also,
The zinc concentration in the diffusion layer 46 is preferably in the range of 2.5% to 10%; if it is less than 2.5%, there is a problem with corrosion resistance, and if it exceeds 10%, no further improvement in corrosion resistance can be expected. .

In the oil cooler thus obtained, the potential increases stepwise in the order of the fin 13, the outer surface of the tube 12, and the inner surface of the tube 12.
The inner surface is not easily corroded and has excellent corrosion resistance.

[0032]

[Effects of the Invention] According to the present invention, the entire tube is made of one pipe, and no welding work is required to manufacture the tube, so a highly reliable oil cooler with no fear of leakage can be achieved. is obtained.

Furthermore, since there is relatively little change in the cross-sectional area of the passage between the small diameter section and other sections, the fluid flow is smooth, the pressure loss of the fluid is small, and the oil cooler has high heat exchange efficiency. can get.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the tube end of an oil cooler obtained by the method according to the invention.

FIG. 2 is a process chart sequentially showing a method for manufacturing an oil cooler according to the present invention.

FIG. 3 is a sectional view corresponding to FIG. 1 showing a modified example of the tube of the oil cooler.

FIG. 4 is a perspective view of the entire oil cooler obtained by the method according to the invention.

FIG. 5 is a perspective view including a fractured cross section of the tube.

FIG. 6 is a partial cross-sectional view of the tube.

FIG. 7 is a partial cross-sectional view of the tube at a different portion from FIG. 6;

FIG. 8 is a longitudinal sectional view of the tube taken along line VIII-VIII in FIG. 6;

FIG. 9 is a perspective view including a fractured cross section showing a modified example of the tube.

FIG. 10 is an exploded perspective view of the fin and tube end.

FIG. 11 is an enlarged cross-sectional view showing the zinc diffusion layer of the tube.

FIG. 12 is an exploded perspective view of a conventional oil cooler.

[Explanation of symbols]

12 Tube 22 Small diameter part 23 Projection

Claims (1)

[Claims] 1. A U-shaped tube 12 is formed by bending the straight tube 12 using a straight aluminum tube 12 having parallel protrusions 23 extending in the tube length direction on its inner surface, Before or after bending the straight tube 12, the protrusion 23 at the end of the tube 12 is
, and by narrowing the same end so that the inner diameter D1 of the same end is almost equal to the diameter D2 of the virtual circle touching the tip of the protrusion 23 other than the same end, a small diameter part for piping connection is formed at the same end. 22
A method for manufacturing an automotive oil cooler, characterized by forming: