U.S. patent application number 14/114655 was filed with the patent office on 2014-02-27 for heat exchange apparatus.
This patent application is currently assigned to Panasonic Corporation. The applicant listed for this patent is Panasonic Corporation. Invention is credited to Yasufumi Takahashi.
Application Number | 20140054017 14/114655 |
Document ID | / |
Family ID | 48140614 |
Filed Date | 2014-02-27 |
United States Patent
Application |
20140054017 |
Kind Code |
A1 |
Takahashi; Yasufumi |
February 27, 2014 |
HEAT EXCHANGE APPARATUS
Abstract
Provided is a heat exchanger capable of performing heat exchange
between a refrigerant and air continuously even if frost forms
thereon. A heat exchanger (1) that exchanges heat between a
refrigerant and air includes: a plurality of heat transfer tubes
(3) extending in an internal flow direction in which the
refrigerant flows; and a corrugated member (4) having a corrugated
shape. The corrugated member (4) includes: fins (5) that are
arranged at at least two different pitches, a relatively large
first pitch (P1) and a relatively small second pitch (P2), in the
internal flow direction; and folded portions (6) that are bonded
alternately in the internal flow direction to the heat transfer
tubes (3) that are adjacent to each other.
Inventors: |
Takahashi; Yasufumi; (Osaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Panasonic Corporation |
Kadoma-shi, Osaka |
|
JP |
|
|
Assignee: |
Panasonic Corporation
Kadoma-shi, Osaka
JP
|
Family ID: |
48140614 |
Appl. No.: |
14/114655 |
Filed: |
October 18, 2012 |
PCT Filed: |
October 18, 2012 |
PCT NO: |
PCT/JP2012/006689 |
371 Date: |
October 29, 2013 |
Current U.S.
Class: |
165/172 |
Current CPC
Class: |
F28F 1/128 20130101;
F28D 2021/0068 20130101; F28F 2215/04 20130101; F25B 39/00
20130101; F28F 1/10 20130101; F28D 1/05383 20130101; F28F 1/126
20130101 |
Class at
Publication: |
165/172 |
International
Class: |
F28F 1/10 20060101
F28F001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2011 |
JP |
2011-229764 |
Claims
1. A heat exchanger that exchanges heat between a refrigerant and
air, comprising: a plurality of heat transfer tubes extending in an
internal flow direction in which the refrigerant flows; and a
corrugated member having a corrugated shape, comprising: a
plurality of fins that are arranged at at least two different
pitches, a relatively large first pitch and a relatively small
second pitch, in the internal flow direction; and a plurality of
folded portions that are bonded alternately in the internal flow
direction to the heat transfer tubes that are adjacent to each
other.
2. The heat exchanger according to claim 1, wherein each of the
fins comprises a plurality of flat portions that are arranged in a
staggered or stepped manner in an external flow direction
perpendicular to the internal flow direction and a direction in
which the heat transfer tubes are arranged, and slits opening in
the external flow direction are formed between the flat
portions.
3. The heat exchanger according to claim 2, wherein the fins are
arranged in such a manner that the fins coincide with each other by
parallel displacement in the internal flow direction.
4. The heat exchanger according to claim 2, wherein widths of the
flat portions are equal in the external flow direction.
5. The heat exchanger according to claim 2, wherein the flat
portions are first flat portions and second flat portions that are
arranged in a staggered manner in the external flow direction.
6. The heat exchanger according to claim 5, wherein the slits are
formed between the first flat portions and the second flat
portions, and a dimension of each of the slits in the internal flow
direction is one half or less of the second pitch.
7. The heat exchanger according to claim 2, wherein the flat
portions form a series of steps descending in a direction inclined
with respect to the external flow direction and the internal flow
direction.
8. The heat exchanger according to claim 1, wherein the fins are
arranged so that the second pitch appears before and after the
first pitch.
9. The heat exchanger according to claim 1, wherein the first pitch
and the second pitch appear alternately.
10. The heat exchanger according to claim 1, wherein when an odd
number of the fins are arranged in series from above in the
internal flow direction, and odd-numbered fins are defined as first
fins and even-numbered fins are defined as second fins, a total sum
of the pitches between the first fins and the fins adjacent to and
below the first fins is equal to a total sum of the pitches between
the second fins and the fins adjacent to and below the second
fins.
11. The heat exchanger according to claim 1, wherein the first
pitch is 1.2 times or more and 3.0 times or less the second
pitch.
12. The heat exchanger according to claim 1, wherein the plurality
of heat transfer tubes comprises at least four of the heat transfer
tubes, and a pair of the corrugated members having the same shape
are bonded to both sides of each of the heat transfer tubes
interposed between the two adjacent heat transfer tubes in such a
manner that the corrugated members coincide with each other by
parallel displacement in an arbitrary direction.
13. The heat exchanger according to claim 1, wherein the adjacent
heat transfer tubes are flat tubes that are parallel to each other.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat exchanger that
exchanges heat between a refrigerant and air.
BACKGROUND ART
[0002] Conventionally, heat exchangers for exchanging heat between
a refrigerant and air are used in air conditioners and the like.
For example, Patent Literature 1 discloses a heat exchanger
including flat tubes in which a refrigerant flows and corrugated
members disposed between the flat tubes. The corrugated members
each have flat portions arranged in a direction in which the flat
tubes extend and raised portions arranged between the flat portions
to join them, and form flow passages for allowing the air to flow
therethrough.
CITATION LIST
Patent Literature
[0003] Patent Literature 1: JP 2004-317002 A
[0004] SUMMARY OF INVENTION
Technical Problem
[0005] In the heat exchanger of Patent Literature 1, the flat
portions are arranged at a constant pitch. Therefore, in the case
where this heat exchanger is used as an outdoor heat exchanger for
an air conditioner, if frost forms thereon during heating
operation, the frost blocks all the air flow passages between the
flat portions simultaneously, which may make it impossible to
continue heat exchange between the refrigerant and air.
[0006] Under these circumstances, it is an object of the present
invention to provide a heat exchanger capable of performing heat
exchange between a refrigerant and air continuously even if frost
forms thereon.
Solution to Problem
[0007] In order to solve the above problem, the heat exchanger of
the present invention is a heat exchanger that exchanges heat
between a refrigerant and air and includes: a plurality of heat
transfer tubes extending in an internal flow direction in which the
refrigerant flows; and a corrugated member having a corrugated
shape. The corrugated member includes: a plurality of fins that are
arranged at at least two different pitches, a relatively large
first pitch and a relatively small second pitch, in the internal
flow direction; and a plurality of folded portions that are bonded
alternately in the internal flow direction to the heat transfer
tubes that are adjacent to each other.
Advantageous Effects of Invention
[0008] In the configuration described above, the fins are arranged
at irregular pitches. Therefore, for example, even if frost forms
on the outdoor heat exchanger during heating operation and narrower
air flow passages formed between the fins with a smaller pitch are
blocked, wider air flow passages formed between the fins with a
larger pitch are less likely to be blocked. Rather, when the
narrower air flow passages formed between the fins with the smaller
pitch are blocked, the flow rate of the air increases between the
fins arranged at the larger pitch, which makes the blockage of the
wider air flow passages less likely to occur. This is because the
frost is removed from the air flow passages by the air flowing
therein at a high flow rate before the frost grows thick enough.
Therefore, the heat exchanger can perform heat exchange between the
refrigerant and the air continuously.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 is a front view of a heat exchanger according to a
first embodiment of the present invention.
[0010] FIG. 2 is an enlarged perspective view of the main part of
the heat exchanger shown in FIG. 1.
[0011] FIG. 3A is an enlarged front view of the main part of the
heat exchanger shown in FIG. 1.
[0012] FIG. 3B is a cross-sectional view taken along the line A-A
in FIG. 3A.
[0013] FIG. 4 is a diagram illustrating how the heat exchanger
works when frost forms thereon.
[0014] FIG. 5 is a perspective view of a corrugated member
according to the first embodiment of the present invention.
[0015] FIG. 6A is an enlarged front view of the main part of a heat
exchanger according to a modification of the first embodiment of
the present invention.
[0016] FIG. 6B is a cross-sectional view taken along the line B-B
in FIG. 6A.
[0017] FIG. 7A is an enlarged front view of the main part of a heat
exchanger according to a second embodiment of the present
invention.
[0018] FIG. 7B is a cross-sectional view taken along the line C-C
in FIG. 7A.
[0019] FIG. 8 is a perspective view of a corrugated member
according to the second embodiment of the present invention.
[0020] FIG. 9A is a diagram illustrating how the heat exchanger
works when frost forms thereon.
[0021] FIG. 9B is a diagram illustrating how the heat exchanger
works on meltwater.
[0022] FIG. 10A is an enlarged front view of the main part of a
heat exchanger according to a modification of the second embodiment
of the present invention.
[0023] FIG. 10B is a cross-sectional view taken along the line D-D
in FIG. 10A.
[0024] FIG. 11 is a perspective view of a corrugated member
according to a modification of the second embodiment.
[0025] FIG. 12A is an enlarged front view of the main part of a
heat exchanger according to another modification of the second
embodiment.
[0026] FIG. 12B is a cross-sectional view taken along the line E-E
in FIG. 12A.
[0027] FIG. 13 is a diagram illustrating how the heat exchanger
works when frost forms thereon and how it works on meltwater.
[0028] FIG. 14 is a perspective view of a corrugated member
according to another modification of the second embodiment.
DESCRIPTION OF EMBODIMENTS
[0029] A first aspect of the present disclosure provides a heat
exchanger that exchanges heat between a refrigerant and air,
including: a plurality of heat transfer tubes extending in an
internal flow direction in which the refrigerant flows; and a
corrugated member having a corrugated shape. The corrugated member
includes: a plurality of fins that are arranged at at least two
different pitches, a relatively large first pitch and a relatively
small second pitch, in the internal flow direction; and a plurality
of folded portions that are bonded alternately in the internal flow
direction to the heat transfer tubes that are adjacent to each
other.
[0030] A second aspect of the present disclosure provides the heat
exchanger as set forth in the first aspect, wherein each of the
fins includes a plurality of flat portions that are arranged in a
staggered or stepped manner in an external flow direction
perpendicular to the internal flow direction and a direction in
which the heat transfer tubes are arranged, and slits opening in
the external flow direction are formed between the flat portions.
According to the second aspect, water resulting from melting of
frost runs down through the slits formed between the flat portions.
Therefore, the water is well drained.
[0031] A third aspect of the present disclosure provides the heat
exchanger as set forth in the second aspect, wherein the fins are
arranged in such a manner that the fins coincide with each other by
parallel displacement in the internal flow direction. According to
the third aspect, between the two adjacent fins, the flat portions
of one of the fins and the counterpart flat portions of the other
fin face each other in the internal flow direction such that the
distance between these facing flat portions in the internal
direction is kept constant at any position in the external flow
direction. In addition, since the air is likely to flow at a
constant rate in the air passage, a less turbulent air flow can be
formed. Furthermore, such a corrugated member can be produced
easily.
[0032] A fourth aspect of the present disclosure provides the heat
exchanger as set forth in the second aspect or the third aspect,
wherein widths of the flat portions are equal in the external flow
direction. According to the fourth aspect, the ratio between the
surface area and the volume of each of the flat portions is
constant. Therefore, the heat transfer efficiency of the fins is
optimized.
[0033] A fifth aspect of the present disclosure provides the heat
exchanger as set forth in any one of the second to fourth aspects,
wherein the flat portions are first flat portions and second flat
portions that are arranged in a staggered manner in the external
flow direction. According to the fifth aspect, a relatively large
slit can be formed between the first flat portion and the second
flat portion. In addition, an air flow passage extending straight
in the external flow direction can be formed. Furthermore, since
the upper and lower edges of the fins are in direct contact with
the heat transfer tubes, these fins can achieve a higher fin
efficiency than louvered fins and the like.
[0034] A sixth aspect of the present disclosure provides the heat
exchanger as set forth in the fifth aspect, wherein the slits are
formed between the first flat portions and the second flat
portions, and a dimension of each of the slits in the internal flow
direction is one half or less of the second pitch. According to the
sixth aspect, the largest possible air passages can be
obtained.
[0035] A seventh aspect of the present disclosure provides the heat
exchanger as set forth in any one of the second to fourth aspects,
wherein the flat portions form a series of steps descending in a
direction inclined with respect to the external flow direction and
the internal flow direction. According to the seventh aspect,
drainage of meltwater resulting from melting of frost can be
facilitated.
[0036] An eighth aspect of the present disclosure provides the heat
exchanger as set forth in any one of the first to seventh aspects,
wherein the fins are arranged so that the second pitch appears
before and after the first pitch. According to the eighth aspect,
spread of frost in the internal flow direction can be
inhibited.
[0037] A ninth aspect of the present disclosure provides the heat
exchanger as set forth in any one of the first to seventh aspects,
wherein the first pitch and the second pitch appear alternately.
According to the ninth aspect, spread of frost in the internal flow
direction can be inhibited.
[0038] A tenth aspect of the present disclosure provides the heat
exchanger as set forth in any one of the first to seventh aspects,
wherein when an odd number of the fins are arranged in series from
above in the internal flow direction, and odd-numbered fins are
defined as first fins and even-numbered fins are defined as second
fins, a total sum of the pitches between the first fins and the
fins adjacent to and below the first fins is equal to a total sum
of the pitches between the second fins and the fins adjacent to and
below the second fins. According to the tenth aspect, the total sum
of the areas of bonding between one of the two adjacent heat
transfer tubes and the corrugated member is equal or almost equal
to the total sum of the areas of bonding between the other one of
the adjacent heat transfer tubes and the corrugated member.
Therefore, the adjacent heat transfer tubes have the same or almost
the same area for heat transfer to/from the corrugated member.
[0039] An eleventh aspect of the present disclosure provides the
heat exchanger as set forth in any one of the first to tenth
aspects, wherein the first pitch is 1.2 times or more and 3.0 times
or less the second pitch. According to the eleventh aspect, it is
possible to allow the corrugated member to have a sufficiently
large heat transfer area as a whole while inhibiting blockage of
the air flow passages due to frost formation.
[0040] A twelfth aspect of the present disclosure provides the heat
exchanger as set forth in any one of the first to eleventh aspects,
wherein the plurality of heat transfer tubes includes at least four
of the heat transfer tubes, and a pair of the corrugated members
having the same shape are bonded to both sides of each of the heat
transfer tubes interposed between the two adjacent heat transfer
tubes in such a manner that the corrugated members coincide with
each other by parallel displacement in an arbitrary direction.
According to the twelfth aspect, in the heat transfer tubes
interposed between the two adjacent heat transfer tubes, the total
sums of the areas of bonding to the corrugated members are equal or
almost equal to each other. Therefore, these heat transfer tubes
have the same or almost the same area for heat transfer to/from the
corrugated members.
[0041] A thirteenth aspect of the present disclosure provides the
heat exchanger as set forth in any one of the first to twelfth
aspects, wherein the adjacent heat transfer tubes are flat tubes
that are parallel to each other.
[0042] Hereinafter, embodiments of the present invention will be
described with reference to the drawings. It should be noted that
the following description of the present invention is merely
exemplary and is not intended to limit the present invention.
First Embodiment
[0043] FIG. 1 shows a heat exchanger 1 according to the first
embodiment of the present invention. This heat exchanger 1
exchanges heat between a refrigerant and air, and is used, for
example, in a room air conditioner or a car air conditioner. As the
refrigerant, a HFC refrigerant, a HC refrigerant, CO2, or the like
can be used.
[0044] Specifically, the heat exchanger 1 includes a plurality of
heat transfer tubes 3 in which the refrigerant flows and a pair of
headers 2 to which both ends of each of the heat transfer tubes 3
are connected. The heat transfer tubes 3 extend in a specific
direction, and are arranged in a direction perpendicular to the
specific direction. Here, the refrigerant flows in the specific
direction in the heat transfer tubes 3. The pair of headers 2
extend in the arrangement direction of the heat transfer tubes 3.
Hereinafter, in order to simplify the description, the specific
direction (an internal flow direction of the present invention),
the arrangement direction of the heat transfer tubes 3, and the
direction perpendicular to these directions (an external flow
direction of the present invention) are referred to as an X
direction, a Y direction, and a Z direction, respectively.
[0045] In this embodiment, the Y direction and the Z direction are
the horizontal directions, and the X direction is the vertical
direction. In other words, the pair of headers 2 extend in the
horizontal direction, and the heat transfer tubes 3 disposed
between the headers 2 extend in the vertical direction. The heat
transfer tubes 3 do not necessarily have to extend in the vertical
direction, and may extend in an oblique direction or in the
horizontal direction. The pair of headers 2 do not necessarily have
to extend in the horizontal direction, and may extend in the
vertical direction.
[0046] As shown in FIG. 2, the adjacent heat transfer tubes 3 are
flat tubes that are parallel to each other, and have a
cross-sectional shape extended in the Z direction. The corrugated
member 4 is disposed between each pair of adjacent heat transfer
tubes 3.
[0047] As shown in FIG. 3A and FIG. 3B, the corrugated member 4 has
a corrugated shape including fins 5 that are arranged in the X
direction and folded portions 6 that are bonded alternatively to
the adjacent heat transfer tubes 3. That is, the folded portions 6
are bonded alternately in the X direction to the adjacent heat
transfer tubes 3. Thus, air flow passages 41 and 42 each exposed to
one of the two adjacent heat transfer tubes 3 and extending in the
Z direction are formed between the fins 5. In this embodiment, as
shown in FIG. 5, the fins 5 have a straight shape extending in the
Z direction. In other words, the fins 5 have a flat shape extending
in the Y and Z directions.
[0048] The fins 5 are arranged at at least two different pitches, a
relatively large first pitch P1 and a relatively small second pitch
P2, in the X direction. As shown in FIG. 3A and FIG. 3B, in this
embodiment, the fins 5 are arranged so that the second pitch P2
appears before and after the first pitch P1. The term "pitch"
refers to the center-to-center distance between the adjacent fins
5, and in this embodiment, the center of the fin 5 refers to the
center line of the flat-shaped fin 5 in its thickness direction (X
direction).
[0049] The first pitch P1 and the second pitch 2 are defined by the
X-direction dimensions of the folded portions 6 that join the
adjacent fins 5. In this embodiment, as shown in FIG. 3A, the
folded portion 6 that is bonded to one of the two adjacent heat
transfer tubes 3 (the left or central heat transfer tube 3 in FIG.
3A) is elongated in the X direction compared to the folded portion
6 that is bonded to the other heat transfer tube 3 (the central or
right heat transfer tube in FIG. 3A). Therefore, the first pitch P1
and the second pitch P2 appear alternately. In other words, the air
flow passage 42 exposed to one of the two adjacent heat transfer
tubes 3 is narrower, while the air flow passage 41 exposed to the
other heat transfer tube 3 is wider.
[0050] In the heat exchanger 1 of this embodiment, the fins 5 are
arranged at irregular pitches. Therefore, as shown in FIG. 4, for
example, even if frost forms on the outdoor heat exchanger during
heating operation and the narrower air flow passages 42 are
blocked, the wider air flow passages 41 are less likely to be
blocked. Rather, when the narrower air flow passages 42 are
blocked, the flow rate of the air increases in the wider air flow
passages 41, which makes the blockage thereof less likely to occur.
Therefore, the heat exchanger can perform heat exchange between the
refrigerant and the air continuously.
[0051] Preferably, the first pitch P1 is 1.2 times or more and 3.0
times or less the second pitch P2. When the ratio P1/P2 is 1.2 or
more, the likelihood of blockage of the wider air flow passages 41
due to frost formation can be reduced sufficiently. When the ratio
of P1/P2 is 3.0 or less, the corrugated members 4 are allowed to
have a sufficiently large heat transfer area as a whole. In view of
these, it is preferable that the ratio P1/P2 satisfy
1.5.ltoreq.P1/P2.ltoreq.1.8.
[0052] As shown in FIG. 1, the heat exchanger 1 has at least four
(seven in FIG. 1) heat transfer tubes 3. As shown in FIG. 2 or FIG.
3A, a pair of corrugated members 4 having the same shape are bonded
to both sides of the heat transfer tube 3 (the central heat
transfer tube 3 in FIG. 2 or FIG. 3A) interposed between the two
adjacent heat transfer tubes 3 in such a manner that these
corrugated members 4 coincide with each other by parallel
displacement in the Y direction. Therefore, in the heat transfer
tubes 3 interposed between the two adjacent heat transfer tubes 3
(five heat transfer tubes 3 in FIG. 1), the total sums of the areas
of bonding to the corrugated members 4 are equal or almost equal to
each other. Thus, these heat transfer tubes 3 interposed between
the two adjacent heat transfer tubes 3 have the same or almost the
same area for heat transfer to/from the corrugated members 4.
Therefore, the refrigerant flowing in each of these heat transfer
tubes 3 is uniformly heated by the air.
[0053] The two corrugated members 4 having the same shape only have
to be bonded to both sides of the heat transfer tube 3 interposed
between the two adjacent heat transfer tubes 3 in such a manner
that these corrugated members 4 coincide with each other by
parallel displacement in an arbitrary direction. For example, the
two corrugated members 4 having the same shape may be bonded to
both sides of the heat transfer tube 3 interposed between the two
adjacent heat transfer tubes 3 in such a manner that these
corrugated members 4 coincide with each other by parallel
displacement in the X and Y directions. Instead, the two corrugated
members 4 having the same shape may be bonded to both sides of the
heat transfer tube 3 interposed between the two adjacent heat
transfer tubes 3 in such a manner that these corrugated members 4
coincide with each other by parallel displacement in the Y and Z
directions. Furthermore, the two corrugated members 4 having the
same shape may be bonded to both sides of the heat transfer tube 3
interposed between the two adjacent heat transfer tubes 3 in such a
manner that these corrugated members 4 coincide with each other by
parallel displacement in the X, Y and Z directions. In any of these
configurations, the heat transfer tubes 3 interposed between the
two adjacent heat transfer tubes 3 have the same or almost the same
area for heat transfer to/from the corrugated members 4. Therefore,
the refrigerant flowing in each of the heat transfer tubes 3 is
uniformly heated by the air.
Modification
[0054] The heat exchanger 1 of the first embodiment can be modified
from various points of view. For example, each of the fins 5 may be
provided with louvers that are inclined with respect to the fin 5
and arranged in the Z direction.
[0055] The fins 5 do not have to be arranged so that the second
pitch P2 appears before and after the first pitch P1. In order to
inhibit blockage of the air flow passages when frost forms, the
fins 5 have to be arranged so that at least one first pitch P1
appears.
[0056] The first pitch P1 and the second pitch P2 do not
necessarily have to appear alternately. A series of the second
pitches may appear either before or after the first pitch or before
and after the first pitch. For example, the fins 5 may be arranged
as shown in FIG. 6A and FIG. 6B. When it is assumed that an odd
number of (seven in FIG. 6B) fins 5 are arranged in series from
above in the X direction, the odd-numbered fins 5 are defined as
first fins and the even-numbered fins 5 are defined as second fins.
In this case, as shown in FIG. 6B, for these odd-numbered fins 5,
the total sum of the pitches between the first fins and the fins
adjacent to and below the first fins is equal to the total sum of
the pitches of the second fins and the fins adjacent to and below
the second fins. In FIG. 6B, these total sums of the pitches are
both 2.times.P2+P1. In this configuration, the total sum of the
areas of bonding between one of the two adjacent heat transfer
tubes 3 and the corrugated member 4 is equal or almost equal to the
total sum of the areas of bonding between the other heat transfer
tube 3 and the corrugated member 4 in a range including positions
corresponding to the odd number of fins 5. Thus, the heat transfer
tubes 3 have the same or almost the same area for heat transfer
to/from the corrugated member 4. Therefore, the refrigerant flowing
in each of the heat transfer tubes 3 is uniformly heated by the
air. In this case, it is preferable that the fins 5 be formed so
that the above relation is satisfied in the entire corrugated
member 4. However, the fins 5 may be formed so that the above
relation is satisfied in a part of the corrugated member 4.
[0057] The fins 5 do not necessarily have to be arranged at two
different pitches, and they may be arranged at three or more
different pitches. For example, in the case where the fins 5 are
arranged at three different pitches, the smallest pitch may be
regarded as the second pitch as defined in this embodiment, and the
medium or largest pitch may be regarded as the first pitch as
defined in this embodiment. Instead, the medium pitch may be
regarded as the second pitch as defined in this embodiment, and the
largest pitch may be regarded as the first pitch as defined this
embodiment.
[0058] The corrugated members 4 having the fins 5 that are arranged
at irregular pitches do not have to be disposed between all pairs
of heat transfer tubes 3, and they may be disposed between at least
one pair of adjacent heat transfer tubes 3. For example, the heat
exchanger may be configured such that the corrugated member having
the fins 5 that are arranged at a constant pitch is disposed
between a pair of heat transfer tubes 3 in a region where the air
flows at the highest rate in the heat exchanger (for example, the
central region of the heat exchanger) and the corrugated members 4
having the fins 5 that are arranged at irregular pitches are
disposed between the other pairs of heat transfer tubes 3.
Second Embodiment
[0059] Next, a second embodiment of the present invention is
described. The second embodiment can be configured in the same
manner as in the first embodiment, unless otherwise stated. The
same or corresponding components are denoted by the same reference
numerals as in the first embodiment, and the description thereof
may be omitted.
[0060] As shown in FIG. 7A and FIG. 7B, the each of the fins 5 is
composed of a plurality of flat portions that are arranged in a
staggered manner in the Z direction. In other words, the plurality
of flat portions are arranged in the Z direction so that slits
opening in the Z direction are formed between the flat portions.
Specifically, the fin 5 undulates in the X direction, and is
composed of first flat portions 51 and second flat portions 52 that
are arranged in a staggered manner in the Z direction. The first
flat portions 51 and the second flat portions 52 extend
perpendicular to the X direction, and slits 53 opening in the Z
direction are formed between them. The fins 5 are arranged in such
a manner that the fins 5 coincide with each other by parallel
displacement in the X direction. Therefore, between the two
adjacent fins 5, the first and second flat portions 51 and 52 of
one of the adjacent fins and the counterpart first and second flat
portions 51 and 52 of the other fin face each other in the X
direction so that the distance between the facing first flat
portions 51 and the distance between the facing second flat
portions 52 are kept constant at any position in the Z direction.
It is preferable that the width of the first flat portion 51 is
equal to that of the second flat portion 52 in the Z direction.
[0061] As shown in FIG. 7A and FIG. 7B, the fins 5 are arranged at
two different pitches, the first pitch P1 and the second pitch P2,
in the X direction. In this embodiment, the center of the fin 5 is
the reference line of the undulations of the fin 5 located at the
midpoint between the first flat portions 51 and the second flat
portions 52 of the fin 5.
[0062] The corrugated member 4 configured as described above can be
produced by making cuts in a flat metal plate (for example, an
aluminum plate) to form the first flat portions 51 and the second
flat portions 52 and then pressing the metal plate into shape or
passing the metal plate through a pair of transfer rollers. In the
corrugated member 4 produced in this manner, the thickness of the
first flat portions 51 and the second flat portions 52 is almost
equal to the thickness of the folded portions 6.
[0063] Also in this embodiment, the fins 5 are arranged at
irregular pitches. Therefore, for example, even if frost forms on
the outdoor heat exchanger during heating operation and the
narrower air flow passages 42 are blocked, the wider air flow
passages 41 are less likely to be blocked. Rather, when the
narrower air flow passages 42 are blocked, the flow rate of the air
increases in the wider air flow passages 41, which makes the
blockage thereof less likely to occur. Therefore, the heat
exchanger can perform heat exchange between the refrigerant and the
air continuously.
[0064] In addition, in this embodiment, each of the fins 5 is
composed of the first flat portions 51 and the second flat portions
52, and the slits 53 are formed between them. Therefore, as shown
in FIG. 9A, even if the inlet side of the narrower air flow
passages 42 is blocked by frost, the air can be introduced into the
narrower air flow passages 42 through the slits 53 on the
downstream side of the passages 42. As a result, a decrease in the
heating capacity can be suppressed. Furthermore, during defrosting
operation for melting the frost, meltwater resulting from the
melting of the frost runs down through the slits 53, as shown in
FIG. 9B. Therefore, the water is well drained. In addition, the
staggered arrangement of the first flat portions 51 and the second
flat portions 52 in the Z direction creates straight air flows in
the Z direction through the slits 53. These straight air flows push
the meltwater resulting from the melting of the frost out in the Z
direction.
[0065] From the viewpoint of maximizing the area of the narrower
air flow passages 42, the X-direction dimension L of the slit 53
formed between the first flat portion 51 and the second flat
portion 52 (see FIG. 7B) is preferably one half or less of the
second pitch P2. Preferably, the dimension L is at least as large
as the thickness of the first flat portion 51 or at least as large
as the thickness of the second flat portion 52. For example, the
X-direction dimension L of the slit 53 may be equal to the shortest
distance between the first flat portions 51 or the second flat
portions 52 of the fins 5 joined by the folded portion 6 that
defines the second pitch P2.
Modification
[0066] The heat exchanger 1 of the second embodiment can be
modified from various points of view. For example, it can be
modified based on the viewpoint described as the modification in
the first embodiment.
[0067] In each of the fins, the plurality of flat portions may be
arranged in the form of at least two steps in the Z direction. For
example, as shown in FIG. 10A, FIG. 10B, and FIG. 11, each of the
fins 5 may be composed of three different flat portions, upper flat
portions 55, middle flat portions 56, and lower flat portions 57.
The upper flat portion 55 forms the top of the steps. The lower
flat portion 57 forms the bottom of the steps. The middle flat
portion 56 is formed at an intermediate position between the upper
flat portion 55 and the lower flat portion 57. Slits 58 opening in
the Z direction are formed between the upper flat portions 55 and
the middle flat portions 56 and between the middle flat portions 56
and the lower flat portions 57. The upper flat portions 55, the
middle flat portions 56, and the lower flat portions 57 are
arranged in the Z direction so that ascending portions and
descending portions appear alternately. However, they do not
necessarily have to be arranged in this order.
[0068] In this modification, the center of the fin 5 is located at
the intermediate position between the upper flat portion 53 and the
lower flat portion 55 and coincides with the center line of the
middle flat portion 54 in its thickness direction. Also in this
modification, as shown in FIG. 10B, the fins 5 are arranged at
irregular pitches (the first pitch P1 and the second pitch P2) in
the X direction. The slits 58 are formed between the upper flat
portions 53 and the middle flat portions 54 and between the middle
flat portions 54 and the lower flat portions 55. Therefore,
according to this modification, the same effects as those of this
embodiment can be exerted.
[0069] Furthermore, as shown in FIG. 12A, FIG. 12B, and FIG. 14,
the plurality of flat portions of each of the fins 5 may form a
series of steps descending in a direction inclined with respect to
the Z direction and the X direction. As shown in FIG. 12B, in each
of the fins 5, the plurality of flat portions 51A to 51F (six flat
portions in this figure) are arranged in the form of steps
descending from the inlet side of the air flow passages 41 and 42
toward the outlet side thereof. Slits 53A opening in the Z
direction are formed between the adjacent flat portions 51A to
51F.
[0070] In this modification, the center of the fin 5 is the
reference line located at the midpoint between the flat portion 51A
disposed on the inlet side of the air flow passage 41 or 42 and the
flat portion 51F disposed on the outlet side of the air flow
passage 41 or 42. As shown in FIG. 12B, the fins 5 are arranged at
irregular pitches (the first pitch P1 and the second pitch P2) in
the X direction. The slits 53A are formed between the adjacent flat
portions 51A to 51F. Therefore, according to this modification, the
same effects as those of this embodiment can be exerted.
Furthermore, as shown in FIG. 13, water resulting from melting of
frost during defrosting operation is pushed by the air flowing in
the air flow passages 41 and 42 toward the outlets of the air flow
passages 41 and 42 along a series of descending flat portions 51A
to 51F. Therefore, according to this modification, drainage of
water resulting from melting of frost can be facilitated.
* * * * *