EP2372282A1

EP2372282A1 - Heat exchanger

Info

Publication number: EP2372282A1
Application number: EP09834573A
Authority: EP
Inventors: Kazuhisa Mishiro; Madoka Ueno
Original assignee: Sharp Corp
Current assignee: Sharp Corp
Priority date: 2008-12-25
Filing date: 2009-07-21
Publication date: 2011-10-05
Also published as: KR20110089366A; US20110226454A1; JP4388994B1; CN102216715A; JP2010151375A; SG171717A1; CN102216715B; WO2010073767A1; AU2009332193A1

Abstract

A heat exchanger 1A has: two header pipes 2 and 3 arranged parallel at an interval; a plurality of flat tubes 4 arranged between the header pipes 2 and 3 with refrigerant passages 5 inside them communicating with the inside of the header pipes 2 and 3; and corrugated fins 6 arranged between adjacent flat tubes 4. To outward facing flat surfaces of, of the plurality of flat tubes 4, those located outermost, outermost corrugated fins 6a having pleats in the shape of a louver are fitted.

Description

Technical Field

The present invention relates to a parallel-flow-type heat exchanger.

Background Art

Parallel-flow-type heat exchangers are widely used in car air conditioners, outdoor units of building air conditioners, etc. In the parallel-flow-type heat exchanges, a plurality of flat tubes are arranged between a plurality of header pipes with a plurality of refrigerant passages inside the flat tubes communicating with the inside of the header pipes and in which fins such as corrugated fins are arranged between the flat tubes.
An example of a conventional parallel-flow-type heat exchanger is shown in FIG. 10. In FIG. 10, the vertical-direction positional relationship is consistent with that in the real world. The heat exchanger 1 has two horizontal header pipes 2 and 3 arranged parallel at an interval in the vertical direction, and has a plurality of vertical flat tubes 4 arranged between the header pipes 2 and 3 with a predetermined pitch in the horizontal direction. The flat tubes 4 are elongate members made by extrusion of metal, and have refrigerant passages 5 formed inside through which to circulate a refrigerant. The flat tubes 4 are arranged with their length direction - the extrusion direction - vertically aligned, and therefore the refrigerant circulation direction through the refrigerant passages 5 is vertical. A plurality of the refrigerant passages 5 with an equal cross-sectional shape and an equal cross-sectional area are arranged in the depth direction in FIG. 10, giving the flat tubes 4 a harmonica-shaped horizontal cross section. The refrigerant passages 5 each communicate with the inside of the header pipes 2 and 3. Between adjacent flat tubes 4, corrugated fins 6 are arranged.
The header pipes 2 and 3, the flat tubes 4, and the corrugated fins 6 are all formed of metal with good heat conduction, such as aluminum. The flat tubes 4 are fixed to the header pipes 2 and 3 by brazing or welding, and so are the corrugated fins 6 to the flat tubes 4.
The heat exchanger 1 shown in FIG. 10 is a so-called down-flow, parallel-flow-type heat exchanger. Between the upper and lower header pipes 2 and 3, a large number of flat tubes 4 are arranged with their length direction vertically aligned and, between the flat tubes 4, corrugated fins 6 are arranged. The heat exchanger 1 thus has a large heat dissipation (heat absorption) area and allows efficient heat exchange. At one end of the lower header pipe 3, a refrigerant port 7 is provided; at one end of the upper header pipe 2 diagonal to the refrigerant port 7, a refrigerant port 8 is provided. It should be understood that the positional relationship between the refrigerant ports 7 and 8 is merely one example and is in no way meant as a limitation. For example, the header pipe 2 may be provided with refrigerant ports 8 one at each end.
In FIG. 10, solid-line arrows indicate the case where the heat exchanger 1 is used as an evaporator, in which case the refrigerant flows in through the refrigerant port 7 of the lower header pipe 3 and flows out through the refrigerant port 8 of the upper header pipe 2. That is, the refrigerant flows from down upward. When the heat exchanger 1 is used as a condenser, the refrigerant flows in the opposite direction; specifically, as dotted-line arrows in FIG. 10 indicate, the refrigerant flows in through the refrigerant port 8 of the upper header pipe 2 and flows out through the refrigerant port 7 of the lower header pipe 3. That is, the refrigerant flows from up downward.
In the heat exchanger 1 of FIG. 10, the corrugated fins are arranged only between the flat tubes 4, and no corrugated fins are fitted to the outward facing flat surfaces of, of the plurality of flat tubes 4, those located outermost. These surfaces, however, are often fitted with corrugated fins, and such examples are seen in Patent Literatures 1 to 3 listed below.
The heat exchanger disclosed in Patent Literature 1 is a parallel-flow-type heat exchanger with flat tubes horizontally aligned, and has corrugated fins fitted on the outward facing flat surfaces of the outermost flat tubes as well. Here, side plates for protecting the fins are arranged at the outer ends of the outermost corrugated fins.
The heat exchanger disclosed in Patent Literature 2 also is a parallel-flow-type heat exchanger with flat tubes horizontally aligned, and has corrugated fins fitted on the outward facing flat surfaces of the outermost flat tubes. Here, side plates for reinforcing the core portion - the portion composed of flat tubes and corrugated fins arranged alternately - are arranged at the outer ends of the outermost corrugated fins.
The heat exchanger disclosed in Patent Literature 3 also is a parallel-flow-type heat exchanger with flat tubes horizontally aligned. Here, side sheets are brazed at the outer ends of corrugated fins at both ends.

Citation List

Patent Literature

[Patent Literature 1] JP-A-H05-79788
[Patent Literature 2] JP-A-2006-64194
[Patent Literature 3] JP-A-2007-139376

Summary of Invention

Technical Problem

In a parallel-flow-type heat exchanger, certainly, fitting corrugated fins to the outward facing flat surfaces of, of a plurality of flat tubes, those located outermost increases the heat dissipation (heat absorption) area and thus enhances the performance of the heat exchanger. However, if a trough part of a corrugated fin, i.e., a part of a corrugated fin where it is fixed to a flat tube, is hit by an object with a sharp point, not only the corrugated fin but also the flat tube may be damaged, possibly leading to leakage of the refrigerant. For this reason, in any conventional arrangement where corrugated fins are arranged also at such positions as described above, protective plates (such as the side palates or the side sheets in above-mentioned Patent Literatures) are arranged, or a protective film is applied, further out (at the outer ends of those corrugated fins) to protect the flat tubes. Inconveniently, providing the protective plates or protective films accordingly increases the number of components and hence the cost.
In view of the foregoing, an object of the present invention is, in a parallel-flow-type heat exchanger, when corrugated fins are fitted to the outward facing flat surface of, of a plurality of flat tubes, those located outermost, to eliminate the need to provide a protective plate or protective film further out.

Solution to Problem

To achieve the above object, according to the present invention, a heat exchanger has: a plurality of header pipes arranged parallel at an interval; a plurality of flat tubes arranged between the plurality of the header pipes with refrigerant passages inside them communicating with the inside of the header pipes; a corrugated fin arranged between adjacent flat tubes; and outermost corrugated fins fitted to outer facing flat surfaces of, of the plurality of flat tubes, those located outermost, in which the outermost corrugated fins have adjacent pleats overlapped in the shape of a louver.
With this structure, even if an object with a sharp point comes close to an outermost corrugated fin, it is hard for it to penetrate through the outermost corrugated fin because of the pleats overlapped in the shape of a louver. Thus, the flat tubes can be sufficiently protected without providing the protective plate (such as the side plate or the side sheet) or protective film.
In the heat exchanger with the above-described structure, when the plurality of flat tubes are arranged with their length direction vertically aligned, it is preferable that the outermost corrugated fins have pleats extending obliquely downward.
With this structure, condensed water and defrost water adhered on the outermost corrugated fins flow along the surfaces of the slanted pleats down to the tips of the pleats, and drip down from there; thus, it is less likely that water accumulates between the pleats of the outermost corrugated fins and thereby blocks the flow of air.
In the heat exchanger with the above-described structure, it is preferable that the plurality of flat tubes be arranged with their length direction horizontally aligned and, of the outermost corrugated fins, at least the bottommost corrugated fin have adjacent pleats overlapped in the shape of a louver.
With this structure, when the parallel-flow-type heat exchanger is used with a side-flow arrangement, even if an object with a sharp point comes close to the bottommost corrugated fin, it is hard for it to penetrate through the bottommost corrugated fin because of the pleats overlapped in the shape of a louver. For this reason, even though the protective plate (such as the side plate or the side sheet) or protective film is disused, it is possible to sufficiently protect the flat tube. Moreover, the condensed water and defrost water adhered on the outermost corrugated fins flow along the surfaces of the slanted pleats down to the tips of the pleats, and drip down from there; since they are not blocked by the protective plate or protective film, the drainage is improved.

Advantageous Effects of Invention

According to the present invention, the outermost corrugated fins have the shape of a louver, which makes it possible to protect the flat tubes to which they are fitted without relying on the protective plates and the protective film. As a result, it is possible to omit the protective plates and the protective film and thereby reduce the component cost.

Brief Description of Drawings

[Fig. 1] A vertical sectional view showing the outline of a parallel-flow-type heat exchanger according to a first embodiment of the present invention.
[Fig. 2] A vertical sectional view showing an outline of a parallel-flow-type heat exchanger according to a second embodiment.
[Fig. 3] An exploded perspective view of components of an air conditioner including the parallel-flow-type heat exchanger according to the second embodiment.
[Fig. 4] A perspective view of a first fitting member used for the fitting of the parallel-flow-type heat exchanger according to the second embodiment.
[Fig. 5] A perspective view of the first fitting member as seen from a different direction.
[Fig. 6] A perspective view of a second fitting member used for the fitting of the parallel-flow-type heat exchanger according to the second embodiment.
[Fig. 7] A perspective view of the second fitting member as seen from a different direction.
[Fig. 8] A perspective view of a third fitting member used for the fitting of the parallel-flow-type heat exchanger according to the second embodiment.
[Fig. 9] A perspective view of the third fitting member as seen from a different direction.
[Fig. 10] A vertical sectional view showing the outline of a conventional parallel-flow-type heat exchanger.

Description of Embodiments

Hereinafter, a first embodiment of the present invention will be described with reference to FIG. 1. In FIG. 1, such components as find their counterparts in the conventional structure shown in FIG. 10 are identified with common reference symbols, and no description of them will be repeated.
A heat exchanger 1A according to the first embodiment is a down-flow type; header pipes 2 and 3 are horizontally aligned, and flat tubes 4 are arranged with their length direction vertically aligned. Outermost corrugated fins 6a are fitted to the outward facing flat surfaces of, of the plurality of flat tubes 4 lined up, those located outermost. The outermost corrugated fins 6a are formed of metal with good heat conduction, such as aluminum. The corrugated fins 6a are fixed to the flat tubes 4 by brazing or welding.
In FIG. 1, solid-line arrows indicate the case where the heat exchanger 1 is used as an evaporator, in which case a refrigerant flows in through a refrigerant port 7 of the lower header pipe 3 and flows out through a refrigerant port 8 of the upper header pipe 2. That is, the refrigerant flows from down upward. When the heat exchanger 1 is used as a condenser, the refrigerant flows in the opposite direction; specifically, as dotted-line arrows in FIG. 1 indicate, the refrigerant flows in through the refrigerant port 8 of the upper header pipe 2 and flows out through the refrigerant port 7 of the lower header pipe 3. That is, the refrigerant flows from up downward.
Each of the outermost corrugated fins 6a has pleats slanted in the same direction as the length direction of the flat tubes 4, so that adjacent pleats overlap each other. Specifically, adjacent pleats overlap each other in the shape of a louver. When the pleats are not slanted, the thickness of the outermost corrugated fin 6a is, at the thinnest part, the thickness of a single material plate of the corrugated fin. By slanting and overlapping the pleats, it is possible to minimize part having the thickness of a single material plate. In this way, even if an object with a sharp point comes close to the outermost corrugated fin 6a from the side, it is likely that it makes contact with part where the pleats are overlapped. The object with a sharp point that has made contact with the part where the pleats are overlapped is stopped by the overlapping pleats; thus, the object is less likely to penetrate through the outermost corrugated fin 6a. For this reason, components such as side plates and side sheets that have been required conventionally to protect the outermost flat tubes 4 are no longer needed, and thus the component cost can be reduced.
To form the outermost corrugated fin 6a so as to have the shape of a louver, it is possible to either fit a corrugated fin that is previously formed to have such a shape to the flat tube 4, or fit a corrugated fin having the same shape as the corrugated fins 6 between the flat tubes 4 to the flat tube 4 and then topple the pleats in one direction, like in domino toppling, to slant.
As mentioned above, the heat exchanger 1A according to the first embodiment is the down-flow type, and the flat tubes 4 are arranged with their length direction vertically aligned. The outermost corrugated fin 6a is fitted such that the pleats extend obliquely downward. In this way, condensed water and defrost water adhered on the outermost corrugated fin 6a flow along the surfaces of the slanted pleats down to the tips of the pleats and drip down from there; thus, it is less likely that water accumulates between the pleats of the outermost corrugated fin 6a and thereby blocks the flow of air.
Next, a second embodiment of the invention will be described with reference to FIGS. 2 to 9. A heat exchanger 1B according to a second embodiment is a side-flow type, in which header pipes 2 and 3 are aligned vertically and flat tubes 4 are arranged with their length direction horizontally aligned. The refrigerant ports 7 and 8 are provided in the header pipe 3 alone. Inside the header pipe 3, partition plates 9a and 9c are provided at an interval in the vertical direction; inside the header pipe 2, a partition plate 9b is provided at a middle height of the partition plates 9a and 9c.
When the heat exchanger 1B is used as an evaporator, a refrigerant flows in through the refrigerant port 7 at the lower side as indicated by a solid-line arrow in FIG. 2. The refrigerant that has entered from the refrigerant port 7 is blocked by the partition plate 9a and flows toward the header pipe 2 via the flat tubes 4. The flow of the refrigerant is indicated by a leftward block arrow. The refrigerant that has entered the header pipe 2 is then blocked by the partition plate 9b and flows toward the header pipe 3 via other flat tubes 4. The flow of the refrigerant is indicated by a rightward block arrow. The refrigerant that has entered the header pipe 3 is then blocked by the partition plate 9c and flows toward the header pipe 2 again via still other flat tubes 4. The flow of the refrigerant is indicated by a leftward block arrow. The refrigerant that has entered the header pipe 2 then flows back to head toward the header pipe 3 again via still other flat tubes 4. The flow of the refrigerant is indicated by a rightward block arrow. The refrigerant that has entered the header pipe 3 then flows out through the refrigerant port 8. As described above, the refrigerant flows from down upward along a zigzag path. Although the number of partition plates is three here, it is merely one example, and the number of partition plates and the resulting number of times the refrigerant flows back can be set arbitrarily as required.
When the heat exchanger 1B is used as a condenser, the refrigerant flows in the opposite direction. Specifically, the refrigerant flows into the header pipe 3 through the refrigerant port 8 as indicated by a dotted-line arrow in FIG. 2, is then blocked by the partition plate 9c and flows toward the header pipe 2 via the flat tubes 4, is then blocked by the partition plate 9b in the header pipe 2 and flows toward the header pipe 3 via other flat tubes 4, is then blocked by the partition plate 9a in the header pipe 3 and flows toward the header pipe 2 again via still other flat tubes 4, then flows back at the header pipe 2 to head toward the header pipe 3 again via still other flat tubes 4, and then flows out through the refrigerant port 7, as indicated by a dotted-line arrow; that is, the refrigerant flows from up downward along a zigzag path.
Of the plurality of flat tubes 4, those located at the topmost and the bottommost are the outermost flat tubes 4; to their outward facing flat surfaces, namely the top surface of the topmost flat tube 4 and the bottom surface of the bottommost flat tube 4, outermost corrugated fins 6a are fitted.
Of the two outermost corrugated fins 6a at the top and bottom, at least the bottom one (the bottommost corrugated fin) has its pleats overlapped in the shape of a louver. In this way, even if an object with a sharp point (for example, a screw) comes close to the bottommost corrugated fin, it is hard for it to penetrate through the bottommost corrugated fin because of the pleats overlapped in the shape of a louver. Thus, it is possible to sufficiently protect the flat tubes 4 even with the protective plate (such as the side plate or the side sheet) disused. Moreover, the condensed water and defrost water adhered on the bottommost corrugated fin flow along the surfaces of the slanted pleats down to the tips of the pleats, and drip down from there; since they are not blocked by the protective plate or protective film, the drainage is improved.
Not only the bottommost corrugated fin but also the outermost corrugated fin 6a at the top (the topmost corrugated fin) may have adjacent pleats overlapped in the shape of a louver. In this way, even if an object with a sharp point comes close to the topmost corrugated fin, it is hard for it to penetrate through the topmost corrugated fin because of the pleats overlapped in the shape of a louver. Thus, it is possible to sufficiently protect the flat tubes 4 even with the protective plate (such as the side plate or the side sheet) disused. In FIG. 2, the topmost corrugated fin also has the adjacent pleats overlapped in the shape of a louver.
FIGS. 3 to 9 show an example when a heat exchanger 1B according to a second embodiment is assembled into an indoor unit of an air conditioner. Here, a core part of the heat exchanger 1B formed of flat tubes 4, corrugated fins 6, and outermost corrugated fins 6a is bent to have an L-shape as seen in a plan view.
In FIG. 3, other than the heat exchanger 1B, there are shown part of components composing a housing of the indoor unit of the air conditioner and fitting members for fitting the heat exchanger 1B to the housing. Specifically, 10 represents a base plate of the housing and 11 represents one side plate of the housing, and these are formed by pressing a steel plate or by combining pressed steal-plate components together.
The heat exchanger 1B is joined to the housing with three different fitting members, all of which are synthetic resin components, and a plurality of screws that join the fitting members to the housing. The fitting members are assembled to header pipes 2 and 3.
A top part of the header pipe 3 is sandwiched by a first fitting member 12 having a shape as shown in FIGS. 4 and 5 and a second fitting member 13 having a shape as shown in FIGS. 6 and 7. The first fitting member 12 and the second fitting member 13 are tightened with a screw 14 to be a single piece. The first and the second fitting member 12 and 13 surround a refrigerant port 8, and also serve to protect the joint of the refrigerant port 8.
A bottom part of the header pipe 3 is sandwiched by another pair of the first and the second fitting member 12 and 13. The posture of the first and the second fitting member 12 and 13 on this side is inverted, in the vertical direction, from that of the first and the second fitting member 12 and 13 surrounding the top part of the header pipe 3. The first and the second fitting member 12 and 13 on this side are tightened with a screw 14 to be a single piece. The first and the second fitting member 12 and 13 surround a refrigerant port 7, and also serve to protect the joint of the refrigerant port 7.
The first and the second fitting member 12 and 13 fitted at the top and bottom parts of the header pipe 3 as described above are (as a single piece) fixed to the housing with another screw 14. This completes the fitting at the header pipe 3 side.
For the fitting at the header pipe 2 side, two pieces of a third fitting member 15 are used. The third fitting members 15 having shapes as shown in FIGS. 8 and 9 are fitted into the top and bottom ends of the header pipe 2, and the third fitting members 15 are then fixed to the housing with screws 14. This completes the fitting at the header pipe 2 side.
As described above, by fitting the heat exchanger 1B to the housing by use of the first, the second, and the third fitting member 12, 13, and 15, all of which are synthetic resin components, it is possible to avoid direct contact of the heat exchanger 1B with the housing. As a result, even though the heat exchanger 1B and the housing are formed of different kinds of metal, it is possible to prevent electrolytic corrosion.
By structuring a parallel-flow-type heat exchanger according to the first embodiment or the second embodiment, it is possible to prevent deformation of the outermost corrugated fin (fin distortion) during production and transportation. This makes it possible to prevent impaired appearance of the product.
Since the corrugated fins can be arranged at the outermost sides even though the side plates and the side sheets are disused, it is possible to increase the heat dissipation area compared with the case where the side plates and the side sheets, and hence the outermost corrugated fins, are disused.
When the parallel-flow heat exchanger is a side-flow type, if a protective plate (such as a side plate or a side sheet) is at the bottommost part, water drainage from the corrugated fin is made difficult, and thus water gradually accumulates and blocks the air passing through the heat exchanger. When the bottommost corrugated fin has pleats overlapped in the shape of a louver and has no protective plate provided at its outer end, defrost water and condensed water flow down without being blocked by the protective plate, and thus they do not block the air passing through the heat exchanger.
It is to be understood that the present invention may be carried out in any other manner than specifically described above as embodiments, and many modifications and variations are possible within the scope of the present invention. For example, it is not essential that the number of the refrigerant passages in the flat tube be two or more. The number of the refrigerant passages may be one.

Industrial Applicability

The present invention finds wide application in parallel-flow-type heat exchangers.

List of Reference Symbols

1A, 1B: heat exchangers
2, 3: header pipes
4: flat tube
5: refrigerant passage
6: corrugated fin
6a: outermost corrugated fin
7, 8: refrigerant ports

Claims

A heat exchanger comprising:
a plurality of header pipes arranged parallel at an interval;

a plurality of flat tubes arranged between the plurality of the header pipes with refrigerant passages inside them communicating with the inside of the header pipes;

corrugated fins arranged between adjacent flat tubes; and

outermost corrugated fins fitted to outward facing flat surfaces of, of the plurality of flat tubes, those located outermost,

wherein

the outermost corrugated fins have pleats overlapped in a shape of a louver.
The heat exchanger according to claim 1,
wherein
the plurality of flat tubes are arranged with a length direction thereof vertically aligned, and the outermost corrugated fins have pleats extending obliquely downward.
The heat exchanger according to claim 1,
wherein
the plurality of flat tubes are arranged with a length direction thereof horizontally aligned, and of the outermost corrugated fins, at least a bottommost corrugated fin has adjacent pleats overlapped in a shape of a louver.