JPH04335993A - Oil cooler - Google Patents

Abstract

PURPOSE:To reduce a fluid resistance without producing deformation of fins and to enhance a heat transfer effect by forming an oil passage between inner and outer cylinders which are coaxially disposed, axially feeding oil in the passage, and mounting predetermined inner fins in the passage. CONSTITUTION:Inner fins 3 are formed by bending thin metal plates in a rectangular wave state, allowing many cut and erected waves to protrude at a predetermined interval on both sides of the waves in a wave advancing direction and alternately forming first and second row waves (a), (b) in an edge direction. The wave (b) is advanced by about 1/3 of a phase at the crest 4 of the wave in the advancing direction with respect to the wave (a). Further, the width (w) of the crest 4 of the wave in the advancing direction is formed wider than that (x) of the trough 5 of the wave, and both the waves (a) and (b) are integrated at the crests 4 and the troughs 5. Further, the entirety is bent cylindrically in the advancing direction of the wave so that the crest 4 is brought into contact with the inner periphery of an outer cylinder 2 and the trough 5 is brought into contact with the outer periphery of an inner cylinder 1, and a space between the adjacent troughs 5 and 5 is reduced in a sector shape so that the fins 3 are interposed in an oil passage 7.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a concentric type oil cooler in which inner fins are interposed in double pipes arranged coaxially. related to things.

0002

2. Description of the Related Art A so-called concentric type oil cooler of a double pipe type is equipped with an offset type inner fin. This inner fin is made by bending a metal plate into a rectangular wave shape and cutting and raising a large number of both sides of the wave to form alternating wave trains with a half-pitch phase shift as shown in FIG.

0003

[Problems to be Solved by the Invention] The conventional offset fin shown in FIG. 3 has a relatively strong rigidity, so it is difficult to insert it into the middle of a concentric type oil cooler formed in a double cylindrical shape. was there. Especially the diameter is 2~
It was difficult to insert it into the oil cooler, which is about 3 cm. This is because when the conventional inner fin is curved as a whole as shown in FIG. 6, the phase difference between the first row wave a and the second row wave b is half the width w of the top part 4 of the fin. This is because the rib effect of the metal plate based on this becomes large, and the rigidity of the vicinity of the top portion 4 and the valley portion 5 and the intermediate portion between the two becomes strong. or,
If the fin is forcibly inserted into the double tube, the rising and falling surfaces of the wave will be abnormally deformed in the conventional inner fin, which has strong rigidity, as shown in Figure 6.
This had the disadvantage of increasing oil flow resistance. moreover,
The flat width w+s (FIG. 3) of the top and valley portions of the rectangular wavy fin becomes wider, and a gap 10 (FIG. 7) is likely to be formed between the outer cylinder 2 and the top 4, which may impair heat transfer. was there.

0004

[Means for Solving the Problems] In order to solve the above problems, the present invention adopts the following configuration. That is, in the oil cooler of the present invention, an oil flow path 7 is formed between an inner cylinder 1 and an outer cylinder 2 that are arranged coaxially, and oil flows in the oil flow path 7 in the axial direction. Inner fins 3 are installed inside the flow path 7. Here, the feature of the present invention is that the inner fin 3 is made by bending a thin metal plate into a rectangular wave shape, and a large number of raised cuts are provided at regular intervals on both sides of the wave, protruding in the direction of travel of the wave. As a result, first row waves a and second row waves b are formed alternately in the wave ridge direction. The phase of the second train wave b advances in the traveling direction relative to the first train wave a by about one-third of the crest 4 of the wave. Furthermore, the width w of the wave crest 4 in the traveling direction is formed wider than the width x of the trough 5, and both rows of waves a and b are integrated at the crest 4 and the trough 5. Furthermore, the whole is curved into a cylindrical shape in the direction of wave propagation so that the top part 4 is in contact with the inner periphery of the outer cylinder 2 and the trough part 5 is in contact with the outer periphery of the inner cylinder 1, and the adjacent trough parts 5, 5
The space between them is reduced to a fan shape, and the inner fins 3 are interposed in the oil flow path 7. The reason why the phase difference is set to about one-third of the width of the top is that it is a value that balances both of reducing the bending rigidity of the fin and effectively preventing the development of a fluid boundary layer.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be explained based on the drawings. FIG. 1 is a perspective view showing a part of the inner fin 3 installed inside this oil cooler. Figure 2 is II- of Figure 1.
A part of the cross section taken along line II is shown. Note that FIG. 3 shows a conventional inner fin. Further, FIG. 4 is a cross-sectional view of a main part of the present oil cooler, and FIG. 5 is a perspective view showing an example of the present oil cooler. This oil cooler is of a so-called concentric type, in which an inner cylinder 1 and an outer cylinder 2 are arranged coaxially with an open space as shown in Fig. 5, and an oil flow path 7 is formed inside them as shown in Fig. 4. A cylindrical inner fin 3 or a pair of semi-cylindrical inner fins is installed in the oil flow path 7. The inner fin 3 is joined by brazing or soldering between the top 4 and the inner circumferential surface of the outer cylinder 2 and between the trough 5 and the outer circumferential surface of the inner cylinder 1. Further, after the inner fin 3 is installed, the inner diameter of both ends of the inner cylinder 1 is expanded and the inner diameter of the inner cylinder 1 is expanded, and the inner fins 3 are joined to both ends of the outer cylinder 2 in a fluid-tight manner. Furthermore, pipes for oil inflow and outflow are provided projecting near both ends of the outer cylinder 2. Then, oil 6 flows in from one pipe, flows in the flow path in which the inner fin is installed as shown by the arrow, and flows out from the other pipe. Cooling water flows within the inner cylinder 1 and around the outer periphery of the outer cylinder 2 of the oil cooler 9, and heat exchange is performed between the cooling water and the oil.

[0006] In such an oil cooler, the inner fins 3 joined to the inside thereof are formed as shown in FIGS. 1 and 2, and are housed as shown in FIG. 4. The fins 3 are formed to be suitable for an oil cooler 9 whose inner cylinder 1 has an extremely small diameter of about 25 mm. For example, a fin is made by bending a heat-conductive metal plate of brass, copper, or aluminum with a thickness of about 0.5 to 0.7 mm into a rectangular wave shape, and cutting and raising parts on both sides of the wave. The first row of waves a and the second row of waves b are alternately formed in the wave ridge direction. Further, as shown in FIG. 2, each wave train is formed so that the width w of the top portion 4 in the wave traveling direction is approximately 30% wider than the width x of the trough portion 5. Furthermore, the phase difference s between the first column wave a and the second column wave b is approximately 1/3 of the width w of the top portion 4, and the rising and falling portions of the second column wave b are in the first column. It is inclined by an angle A with respect to that of wave a. This inclination angle A is designed so that when the inner fin 3 is installed inside as shown in FIG. be. Note that the top and bottom portions of the first wave a and the second wave b are integrated. In this embodiment, the amplitude (height) of the rectangular wave of the inner fin 3 is approximately 2 to 3 mm, and the width w of the top portion 4 is 1
~ 1.5mm, width x of trough 5 is 0.7~1.3m
m, and the width of each row wave is about 1 to 1.5 mm. The design of each of these dimensions can be changed as appropriate depending on the size of the oil cooler 9 and other factors.

The inner fin 3 thus constructed is housed between the inner tube 1 and the outer tube 2 so that the trough portion 5 side is compressed and the top portion 4 side is expanded. The space formed between the adjacent valleys 5, 5 is reduced into a fan shape, and is formed so that its width x' and the width x of the previous valley 5 are approximately equal. Further, the space interval width w' between the top portions 4, 4 is formed to be approximately equal to the width w of the top portion 4. Note that the surfaces of the outer cylinder 2 and the inner cylinder 1 are coated with brazing material or solder material in advance. Next, both ends of the inner cylinder 1 are widened to make contact with the outer cylinder 2. At the same time, an expansion jig is inserted into the inner surface of the inner cylinder 1 to slightly enlarge the diameter of the inner cylinder 1. Then, the outer peripheral surface of the inner cylinder 1 and the valley part 5 of the inner fin 3 come into close contact, and the top part 4 and the inner periphery of the outer cylinder 2 come into close contact. Then, inlet and outlet pipes are arranged at both ends of the outer cylinder 2, respectively, and the whole is inserted into a high-temperature furnace. Then, the brazing material or solder material previously coated between the contact portions of each component, or the brazing foil interposed between them is melted in a furnace. The assembly is then cooled, and the contact portions are liquid-tightly brazed or soldered to complete the oil cooler.

[0008]

[Effects of the Invention] In the oil cooler of the present invention, the width x of the valley portion 5 of the inner fin 3 that contacts the inner cylinder 1 is formed to be smaller than the width w of the top portion 4 of the fin 3 that contacts the outer cylinder 2. Therefore, the entire inner fin 3 can be easily deformed into a cylindrical shape, and can be precisely installed between the inner and outer cylinders 1 and 2 of the oil cooler 9, which has a particularly small radius of curvature. This makes it possible to lower the fluid resistance of the oil and enhance the heat transfer effect without causing fin collapse. Furthermore, since the phase difference between the first wave a and the second wave b is about one-third, the widths w+s and x+s of the flat surfaces generated at the top 4 and the trough 5 are narrower than before. , the gap between the inner fin 3 and the curved surfaces of the outer cylinder 2 and inner cylinder 1 with which they come into contact is made as small as possible, and
It can promote heat transfer with. Furthermore, since the phase difference between the first row wave and the second row wave is about one-third, it becomes easy to curve the inner fin 3 as shown in FIG. 4. That is, since the amount of protrusion of the cut and raised portions formed on the side surfaces of the rectangular waves is small, the rib effect is smaller than in the past, and the entire inner fin 3 can be easily formed into a cylindrical shape. . Moreover, the first row wave and the second row wave are formed alternately,
Efficiently prevents the development of a boundary layer due to oil flow and improves heat transfer. Furthermore, since the phase difference is small, the amount of cutting and raising can be small, making fin molding easier and improving molding accuracy. That is, the occurrence of twisting or variation in the fins after molding is reduced, and the inner fins 3 are in reliable contact with the inner cylinder 1 and the outer cylinder 2, resulting in an oil cooler with high heat conductivity.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a part of an inner fin 3 installed inside an oil cooler of the present invention.

FIG. 2 is a sectional view taken along line II-II in FIG. 1.

FIG. 3 is a schematic diagram of an inner fin 3 installed in a conventional oil cooler.

FIG. 4 is a partial axial cross-sectional view of the oil cooler of the present invention.

FIG. 5 is a perspective view of the oil cooler of the present invention.

FIG. 6 is a portion of an axis-perpendicular cross-sectional view of a conventional oil cooler.

FIG. 7 is an enlarged view of the same part.

[Explanation of symbols]

1 Inner cylinder 2 Outer cylinder 3 Inner fin 4 Top 5 Tanibe 6 Oil 7 Oil flow path 8 Cooling water 9 Oil cooler 10 Voids

Claims (1)

[Claims] Claim 1: An inner cylinder (1) and an outer cylinder (
In an oil cooler in which oil flows in the axial direction through an oil passage (7) formed between the inner fin (2) and an inner fin (3) installed in the oil passage (7), In 3), a thin metal plate is bent into a rectangular wave shape, and a large number of raised cuts are provided at regular intervals on both sides of the wave, protruding in the direction of wave propagation, and the first row of waves are alternately formed in the direction of the wave ridgeline. (a) and a second train wave (b) are formed, and the second train wave (b) is a third of the top (4) of the wave in the traveling direction with respect to the first train wave (a). The phase advances by 1, and the width (w) of the wave crest (4) in the traveling direction becomes the trough (5).
is formed wider than the width (x) of both waves (a) (
b) is integrated at the top (4) and trough (5), the top (4) is in contact with the inner periphery of the outer cylinder (2), and the trough (5) is integrated with the inner cylinder (1). The whole is curved into a cylindrical shape in the traveling direction of the wave so as to be in contact with the outer periphery of the wave, and adjacent troughs (5)
(5) The space between the oil passages (7 and 7) is reduced to a fan shape.
) is installed in the oil cooler.