US20060000587A1

US20060000587A1 - Side plate with reduced warp for heat exchanger and heat exchanger using the same

Info

Publication number: US20060000587A1
Application number: US11/171,780
Authority: US
Inventors: Yasuhiro Ando; Terumi Nishida
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 2004-07-05
Filing date: 2005-06-30
Publication date: 2006-01-05
Also published as: JP2006017429A

Abstract

A warp of a side plate in the lengthwise direction is reduced by means of a simple shape formed by pressing without increasing a press machine in size. A side plate, for a heat exchanger, to be arranged at the end of a core section 13 composed of tubes 11 and fins 12 has a long and narrow shape with a U-shaped section formed by a bottom section 21 and bent sections 22 and 23 formed by bending both ends of the bottom section 21 in the width direction, and a plurality of recesses 24 extending in the width direction are formed by pressing the bottom section 21 at predetermined intervals c.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to a side plate, for a heat exchanger, formed by bending so as to have a U-shaped section and a heat exchanger using the same, and is preferably applicable to, for example, a condenser for vehicle air conditioning.
2. Description of the Related Art
In a conventional condenser for vehicle air conditioning, a side plate formed by bending so as to have a U-shaped section is arranged at the end of a core section composed of flat tubes and corrugated fins. Specifically, the side plate is joined by brazing to the corrugated fin at the outermost side of the core section and to the end of a header tank and serves to reinforce the core section and protect the corrugated fin, etc.
The side plate described above is, as shown in FIG. 5, a long and narrow member having a U-shaped section formed by a bottom section 21 and bent sections 22 and 23 on both sides thereof, and its length dimension L ranges between approximately 250 mm and 850 mm in accordance with the specifications of the condenser.
Being such a long and narrow member, a phenomenon occurs that the side plate warps arch-wise in the lengthwise direction when the side plate is formed by bending a plate-like aluminum material using a press die so as to have a U-shaped section. This is because a residual stress state of the material is unbalanced. The reference letter “a” in FIG. 5 indicates the arch-like warp.
The cause of the occurrence of the warp a in the lengthwise direction of the side plate can be explained using FIG. 6. When forming the bent sections 22 and 23 by bending, a contracted (compressive) region A is formed in the inner part of the bent section and a stretched (tensile) region B is formed in the outer part of the bent section.
As the contracted (compressive) region A in the inner part of the bent section and the stretched (tensile) region B in the outer part in the bent section exist concurrently, if the distortion of the side plate in the lengthwise direction is observed, a stretched distortion C occurs in the inner part of the bent section and a contracted distortion D occurs in the outer part of the bent section. As a result, the side plate is brought into an unbalanced stress state, under stress, because of the coexistence of the contraction and stretch. Therefore, a phenomenon occurs that the side plate warps arch-wise in the lengthwise direction.
The inventors of the present invention have also confirmed that the arch-like warp a reaches 5.6 mm when the length L=814 mm.
If such a large warp a occurs, it becomes difficult to assemble the ends of the side plate in the lengthwise direction to the ends of the header tanks in the core assembling process before integrally brazing a condenser. Further when integrally brazing a condenser, a gap is produced between the side plate and the corrugated fin owing to the warp a, and poor joinability of the corrugated fin results.
Therefore, the inventors of the present invention have examined countermeasures such as so-called “forming in a holding state” in which pressure is applied to the bent sections 22 and 23 of the side plate in the direction of its height h, a countermeasure in which the back pressure to be applied to the bottom section 21 of the side plate is increased, etc. However, as pressure must be applied to an area to be pressed of a wide range across the entire length of the side plate in the lengthwise direction in any of these countermeasures, a high pressure is required and a large press machine is required. Because of this, the facility cost is raised and, therefore, these countermeasures are not practical.

SUMMARY OF THE INVENTION

The above-mentioned points being taken into account, the object of the present invention is to reduce a warp of a side plate in the lengthwise direction with a simple pressed form without the need to increase a press machine in size.
In order to attain the above-mentioned object, a side plate for a heat exchanger according to a first aspect of the present invention is characterized by being arranged at the end of a core section (13) composed of tubes (11) and fins (12), and having a long and narrow shape with a U-shaped section comprising a bottom section (21) and bent sections (22, 23) formed by bending both ends of the bottom section in the width direction thereof, and in that a plurality of recesses (24) extending in the width direction are formed by pressing the bottom section (21) at predetermined intervals (c).
According to this aspect, by forming the plurality of recesses (24) on the side plate bottom section (21) by pressing, a contracted region can be formed not only in the inner part of the bent section of the side plate but also in the outer part of the bent section.
Due to this, it is possible to bring the side plate into a balanced stress state, under no stress, and, as a result, the warp of the side plate in the lengthwise direction can be reduced.
Further, the recesses (24) can be formed only by partly pressing the bottom section (21) at the predetermined intervals (c), and as it is not necessary to apply a high pressure to the entire bottom section (21), the press machine can be prevented from becoming large in size.
In a side plate for a heat exchanger in a second aspect of the present invention according to the first aspect, the recesses (24) can be formed on the inner surface of the bottom section (21).
In a side plate for a heat exchanger in a third aspect of the present invention according to the first aspect, the recesses (24) may be formed on the outer surface of the bottom section (21).
In a side plate for a heat exchanger in a fourth aspect of the present invention according to any one of the first to third aspects, if the recesses (24) are formed into a shape having an arc-like section, the recesses (24) can be formed smoothly and the pressure to be applied for forming the recesses (24) can be reduced.
In a side plate for a heat exchanger in a fifth aspect of the present invention according to any one of the first to fourth aspects, the recesses (24) can be formed at the same time that the bent sections (22, 23) are formed by bending.
In a side plate for a heat exchanger in a sixth aspect of the present invention according to any one of the first to fourth aspects, the recesses (24) may be formed after the bent sections (22, 23) are formed by bending.
A heat exchanger in a seventh aspect of the present invention is characterized by comprising a core section (13) including of tubes (11) and fins (12) and side plates (19, 20) arranged on the ends of the core section (13), and in that the heat exchanger comprises the side plates (19, 20) for a heat exchanger in any one of the first to sixth aspects.
Due to this, it is possible to provide a heat exchanger capable of exhibiting the function and effect in the first to seventh aspects described above.
A heat exchanger in an eighth aspect of the present invention according to the seventh aspect is characterized in that header tanks (14, 15) with which the ends of the tubes (11) are communicated respectively are arranged on both ends of the tubes (11) in the lengthwise direction, the fins (12) are corrugated fins (12), and the tubes (11), the corrugated fins (12), and the header tanks (14, 15) are integrally joined by brazing and at the same time, the side plates (19, 20) are integrally joined by brazing to the corrugate fins (12) located on the ends of the core section (13) and to the ends of the header tanks (14, 15).
According to this aspect, in the heat exchanger assembled by brazing, the distance between the side plates (19, 20) and the corrugated fins (12) is reduced by reducing the warp of the side plates (19, 20) and thereby the joinability can be ensured and, at the same time, the workability in assembling the side plates (19, 20) to the ends of the header tanks (14, 15) can be improved.
The symbols in the parenthesis attached to each means described above indicate a correspondence with a specific means in the embodiments to be described later.
The present invention may be more fully understood from the description of the preferred embodiments of the invention set forth below, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:
FIG. 1 is a perspective view showing a general configuration of a condenser to which the present invention is applied.
FIG. 2A is partly broken perspective view showing a side plate according to a first embodiment of the present invention.
FIG. 2B is an essential part sectional view of the side plate in the lengthwise direction.
FIG. 2C is an essential part sectional view of the side plate in the width direction.
FIG. 3 is a diagram for explaining a function of reducing the warp of the side plate according to the first embodiment.
FIG. 4 is a partly broken perspective view showing a side plate according to a second embodiment of the present invention.
FIG. 5 is a perspective view showing a side plate according to the prior art.
FIG. 6 is a diagram for explaining the cause of the occurrence of the warp of the side plate according to the prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

The present embodiment relates to a condenser for vehicle air conditioning and, first of all, an outline of the condenser for vehicle air conditioning is explained by referring to FIG. 1. As is widely known, a condenser 10 is connected to the discharge side of a refrigerant of a compressor in a refrigerating cycle and cools and condenses the gas refrigerant discharged from the compressor with the outside air.
The condenser 10 has a core section 13 comprising a plurality of flat tubes 11 extending in the horizontal direction and a plurality of corrugated fins 12, and on both the right end and the left end of the core section 13, header tanks 14 and 15 having a substantially cylindrical shape and extending in the vertical direction are arranged, and both ends of the flat tubes 11 are communicated with the inside of the header tanks 14 and 15.
At the upper part of the header tank 14 on one side, an inlet join 16 through which a discharged gas refrigerant, from a compressor, flows in, is connected and at the lower part of the header tank 15 on the other side, an outlet join 17 through which a refrigerant condensed and cooled in the core section 13 flows out, is connected.
The condenser 10 in the present embodiment forms a condensation section 13 a for condensing a gas refrigerant at the upper part of the core section 13 and a cooling section 13 b for cooling a liquid refrigerant after condensation at the lower part of the core section 13. Then, a receiver 18 is integrally formed with the header tank 14 on the one side, the refrigerant at the outlet of the condensation section 13 a is introduced into the inside of the receiver 18, the refrigerant is separated into gas and liquid in the receiver 18, and only the liquid refrigerant is caused to flow into the cooling section 13 b.
On the other hand, side plates 19 and 20 are arranged on both the upper end and the lower end of the core section 13. The side plates 19 and 20 have a long and narrow shape extending in the horizontal direction on both the upper end and the lower end of the core section 13 and are formed by bending so as to have a U-shaped section.
Both ends of the side plate 19 in the lengthwise direction on the upper side are joined to the top ends of both the header tanks 14 and 15. The U-shaped bottom section of the side plate 19 on the upper side comes into contact with and is joined to the corrugated fin 12 at the uppermost part of the core section 13.
Both ends of the side plate 20 in the lengthwise direction on the lower side are joined to the bottom ends of both the header tanks 14 and 15. The U-shaped bottom section of the side plate 20 on the lower side comes into contact with and is joined to the corrugated fin 12 at the lowermost part of the core section 13. A plurality of mounting holes 19 a and 20 a are bored in the side plates 19 and 20 and the condenser 10 is mounted to the body of a vehicle using the mounting holes 19 a and 20 a, and means such as screw fixing.
The constituent members 11, 12, and 14 to 20 of the condenser shown in FIG. 1 are formed of aluminum alloy and are assembled into a structure shown in FIG. 1, and the assembled body is brought into a heating oven while being held with a jig. The assembled body is heated to a temperature higher than the melting point of the brazing material in the heating oven and each member is integrally brazed into a single unit.
Because of this, in order to smoothly carry out assembling of the condenser before the brazing process and ensure excellent brazing properties, it is important to keep the arch-like warp a (refer to FIG. 6 described above) of the side plates 19 and 20 in the lengthwise direction as small as possible.
Countermeasures to reduce the arch-like warp a in the present embodiment are explained based on FIGS. 2A and 2B. FIG. 2A is a partly broken perspective view of the side plates 19 and 20, FIG. 2B is an essential part sectional view of the side plates 19 and 20 in the lengthwise direction, and FIG. 2C is an essential part sectional view of the side plates 19 and 20 in the width direction (direction perpendicular to the lengthwise direction).
The side plates 19 and 20 each have a U-shaped section formed by the bottom section 21 and the bent sections 22 and 23 located on both the right end and the left end of the bottom section 21 in the width direction. The material of the side plates 19 and 20 is a bare aluminum material with no clad brazing material. JIS (Japanese Industrial Standard)-A 3003 is used in the present embodiment, and its thickness t is, for example, 1.6 mm.
A plurality of recesses 24 having a minuscule depth b of the bottom section 21 are parallel formed on the U-shaped inner surface at constant intervals c across the entire length of the side plates 19 and 20 in the lengthwise direction. The recess 24 has a long and narrow shape extending in the width direction of the bottom section 21 and its section has an arc shape (R-shape) with a predetermined radius as shown in FIG. 2B. The depth is, for example, as minuscule as 0.04 mm. The width d of the recess 24 is, for example, 1.5 mm.
The length f of the recess 24 is 8 mm. Here, the width dimension e of the bottom section 21 is, for example, 12.8 mm and, therefore, the length f of the recess 24 occupies 60% or more of the width dimension e of the bottom section 21.
On each of both ends of the recess 24 in the lengthwise direction, a slope surface 24 a is formed so that both ends of the recess 24 in the lengthwise direction are smoothly connected to the inner surface of the bottom section 21. Here, the angle θ between the slope surface 24 a and the line vertical to the bottom section 21 is, for example, 75°.
The formation of the above-mentioned recesses 24 can be carried out together with the formation of the side plates 19 and 20 by bending. In other words, protrusions (rib-shaped) each having an arc-like section for partly pressing the bottom section 21 at the constant intervals c are formed in advance in a press die for forming by bending a plate-like aluminum material into a side plate comprising the bottom section 21 and the bent sections 22 and 23 and having a U-shaped section. Due to this, it is possible to form the U-shaped section by bending using the press die and simultaneously to form a number of recesses 24 by pressing.
The reason why it is possible to reduce the warp of the side plates 19 and 20 by forming the recesses 24 by pressing is explained below. As shown in FIG. 3, it is possible to produce a contraction stress E by forming the recesses 24 by pressing and thereby, a contraction region F is formed also in the outer part of the bent section.
In other words, the stretched (tensile) region B in the outer part of the bent section in FIG. 6 is changed to the contracted region F in the present embodiment, that is, both the regions in the inner part and in the outer part of the bent section are the contracted (compressive) regions A and F and a balanced stress state, under no stress, is established.
As a result, it is possible to reduce the arch-like warp of the side plate in the lengthwise direction by producing a stretched distortion both in the inner part and in the outer part of the bent section in the lengthwise direction of the side plate and at the same time, bringing the stretched distortions in the inner part and in the outer part of the bent section into a balanced state.
The inventors of the present invention measured the magnitude of the arch-like warp a while changing the interval c between the recesses 24 based on the above-mentioned design example with the total length L=814 mm, and obtained the following results.
Interval c=40 mm . . . warp a=2.6 mm
Interval c=30 mm . . . warp a=1.5 mm
Interval c=20 mm . . . warp a=0.3 mm
As described above, it has been found that the warp a=5.6 mm in the conventional example shown in FIG. 5 can be more than halved by setting the interval c between the recesses 24 to a value equal to or less than 40 mm.
From the results discussed above, it will be understood that the smaller the interval c, the more the warp a can be reduced. However, if the interval c is reduced excessively, the contracted region F in the outer part of the bent section becomes dominant over the contracted region A in the inner part of the bent section and the side plates. 19 and 20 warp in the opposite direction of the warp a shown in FIG. 5. Therefore, in the present embodiment, it is preferable to set the lower limit of the interval c to around 20 mm.
According to a study by the inventors of the present invention, it is possible to form the recesses 24 after forming the side plates 19 and 20 by bending. It has been confirmed that the arch-like warp a can be similarly reduced in this manner.
On the other hand, if the formation of the recesses 24 on a plate-like aluminum material is carried out before the formation of the side plates 19 and 20 by bending, a phenomenon occurs in that, due to the residual stress accompanying the formation of the recesses 24, the plate-like aluminum material warps in the opposite direction of the warp a in FIG. 5. The occurrence of the warp makes it difficult to insert the plate-like aluminum material into the press die. Therefore, it is not preferable to carry out the formation of the recesses 24 before the formation of the side plates 19 and 20 by bending.

Second Embodiment

Although the recesses 24 are formed on the inner surface of the bottom section 21 of the side plates 19 and 20 having a U shaped section in the first embodiment, the recesses 24 are formed on the outer surface of the bottom section 21 in the second embodiment as shown in FIG. 4.
It has been confirmed that even if the recesses 24 are formed on the outer surface of the bottom section 21 as described above, the warp a can be reduced as in the first embodiment.
However, as is seen from FIG. 1, the corrugated fin 12 is joined by brazing to the outer surface of the bottom section 21 of the side plates 19 and 20 and, therefore, the formation of the recesses 24 on the outer surface deteriorates the joinability (brazing properties) between the side plates 19 and 20 and the corrugated fin 12. Therefore, from the viewpoint of the joinability, the first embodiment is preferable to the second embodiment.

Other Embodiments

In the above mentioned embodiments, although the shape of the section of the recess 24 is an arc, it is also possible to obtain the same effect to reduce the arch like warp a even if the shape of the section of the recess 24 is formed into a trapezoidal shape. However, as a trapezoidal shape is formed of combined flat surfaces, the pressure to be applied for forming the recesses by pressing is increased compared to the case of an arc shape.
In the above mentioned embodiments, although the interval c between the recesses 24 is constant across the entire area of the bottom section 21 in the lengthwise direction, it may be possible to change the interval c between the recesses 24 in the lengthwise direction of the bottom section 21 as the need arises.
In the above mentioned embodiments, examples are shown in which the present invention is applied to the side plates 19 and 20 in a condenser in a refrigerating cycle, however, the present invention can be similarly applied to a heat exchanger such as a radiator because side plates having a U shaped section are mounted on a heat exchanger such as a radiator for cooling the cooling water for a vehicle engine.
While the invention has been described by reference to specific embodiments chosen for the purposes of illustration, it should be apparent that numerous modifications could be made thereto, by those skilled in the art, without departing from the basic concept and scope of the invention.

Claims

1. Side plates for a heat exchanger arranged at ends of a core section comprising tubes and fins, wherein the side plates with a U shaped section comprising a bottom section and bent sections formed by bending both ends of the bottom section in a width direction thereof, and

a plurality of recesses extending in the width direction are formed by pressing the bottom section at predetermined intervals.

2. The side plates for a heat exchanger as set forth in claim 1, wherein the recesses are formed on an inner surface of the bottom section.

3. The side plates for a heat exchanger as set forth in claim 1, wherein the recesses are formed on an outer surface of the bottom section.

4. The side plates for a heat exchanger as set forth in claim 1, wherein each of the recesses has an arc like section.

5. The side plates for a heat exchanger as set forth in claim 1, wherein the recesses are formed at the same time that the bent sections are formed by bending.

6. The side plates for a heat exchanger as set forth in claim 1, wherein the recesses are formed after the bent sections are formed by bending.

7. A heat exchanger comprising a core section including tubes and fins and side plates arranged at the ends of the core section, wherein the heat exchanger comprises the side plates for a heat exchanger as set forth in claim 1.

8. The heat exchanger as set forth in claim 7, wherein:

header tanks with which ends of the tubes are respectively communicated are arranged on both ends of the tube in the lengthwise direction;

the fins are corrugated fins;

the tubes, the corrugated fins, and the header tanks are integrally joined by brazing; and

each of the side plates is integrally joined by brazing to the corrugated fin located on the end of the core section and to ends of the header tanks.