U.S. patent application number 14/399979 was filed with the patent office on 2015-04-23 for heat exchanger and air-conditioning apparatus having the same.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Ryoichi Ikeda, Takuya Matsuda, Nobuaki Miyake, Akio Murata, Hiroki Okazawa, Wataru Suzuki. Invention is credited to Ryoichi Ikeda, Takuya Matsuda, Nobuaki Miyake, Akio Murata, Hiroki Okazawa, Wataru Suzuki.
Application Number | 20150107803 14/399979 |
Document ID | / |
Family ID | 50067513 |
Filed Date | 2015-04-23 |
United States Patent
Application |
20150107803 |
Kind Code |
A1 |
Ikeda; Ryoichi ; et
al. |
April 23, 2015 |
HEAT EXCHANGER AND AIR-CONDITIONING APPARATUS HAVING THE SAME
Abstract
A heat exchanger includes a plurality of fins stacked with a
predetermined fin pitch between them, and a plurality of heat
transfer tubes which extend through the fins in the stack direction
and have a flat cross-sectional shape, wherein the fins have a
plurality of notches in a shape corresponding to the
cross-sectional shape of the heat transfer tube on an end portion
in the longitudinal direction, a collar is formed on an edge of the
plurality of notches, the heat transfer tubes are inserted into the
notches, a fin pitch between a portion of the plurality of fins is
larger than a fin pitch between the other portion of the fins, and
the larger fin pitch is larger than at least the height of the
collar.
Inventors: |
Ikeda; Ryoichi; (Tokyo,
JP) ; Murata; Akio; (Tokyo, JP) ; Miyake;
Nobuaki; (Tokyo, JP) ; Okazawa; Hiroki;
(Tokyo, JP) ; Suzuki; Wataru; (Tokyo, JP) ;
Matsuda; Takuya; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ikeda; Ryoichi
Murata; Akio
Miyake; Nobuaki
Okazawa; Hiroki
Suzuki; Wataru
Matsuda; Takuya |
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo
Tokyo |
|
JP
JP
JP
JP
JP
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
50067513 |
Appl. No.: |
14/399979 |
Filed: |
August 8, 2012 |
PCT Filed: |
August 8, 2012 |
PCT NO: |
PCT/JP2012/005041 |
371 Date: |
November 10, 2014 |
Current U.S.
Class: |
165/121 ;
165/172 |
Current CPC
Class: |
F28D 1/0476 20130101;
F28F 2215/14 20130101; F28F 2215/12 20130101; F28F 1/32 20130101;
F28F 2215/04 20130101; F24F 1/18 20130101; F28F 1/12 20130101; F28D
1/024 20130101 |
Class at
Publication: |
165/121 ;
165/172 |
International
Class: |
F28F 1/12 20060101
F28F001/12 |
Claims
1. A heat exchanger comprising: a plurality of fins stacked with a
predetermined fin pitch therebetween; and a plurality of heat
transfer tubes which are disposed with a predetermined pitch
therebetween in a longitudinal direction of the fins and extend
through the fins in a direction in which the fins are stacked,
wherein each of the plurality of heat transfer tubes has a flat
cross-sectional shape, each of the plurality of fins includes a
plurality of notches conforming to the cross-sectional shape of
each heat transfer tube on an end portion of each fin in the
longitudinal direction, each of the plurality of notches includes a
collar formed on an edge thereof, the heat transfer tubes are
respectively inserted into the notches, the plurality of fins
include one set of fins having a fin pitch larger than a fin pitch
of another set of fins, and the larger fin pitch is larger than at
least a height of the collar corresponding to an amount of
extension of the collar from a plate surface of the fin.
2. An air-conditioning apparatus comprising: a housing which is
provided with an air inlet and an air outlet; the heat exchanger of
claim 1 as disposed in the housing; and a fan disposed in the
housing.
3. The air-conditioning apparatus of claim 2, wherein the housing
accommodates an accommodation object in an air flow passage between
the heat exchanger and the fan, and in the heat exchanger, a fin
pitch in an area having a distance from the accommodation object,
which is not more than a predetermined distance, is the larger fin
pitch.
4. The air-conditioning apparatus of claim 3, wherein the housing
is provided with the air inlet formed in at least one side face
thereof and the air outlet formed in a top face thereof, the heat
exchanger faces the air inlet, the fan includes a propeller fan and
faces the air outlet, and in the heat exchanger, a fin pitch in an
area which satisfies L/D.ltoreq.0.15 is the larger fin pitch, where
D is a diameter of the propeller fan, and L is a distance between
the heat exchanger and the accommodation object.
5. The air-conditioning apparatus of claim 3, wherein in the heat
exchanger, letting fp2 be the larger fin pitch, and fp1 be the fin
pitch of the other set of fins, the fin pitch fp2 is set so that a
coefficient of performance of the air-conditioning apparatus
equipped with the heat exchanger having both the fin pitches fp1
and fp2 in two fin areas respectively defined by the one set of
fins and the other set of fins is not less than 95% of a
coefficient of performance of an air-conditioning apparatus
equipped with a heat exchanger having only the fin pitch fp1 in the
two fin areas.
6. The air-conditioning apparatus of claim 3, wherein the
accommodation object includes a control panel which is disposed on
one side face of the housing, the air inlet is formed at least in a
side face of the housing which is adjacent to the one side face
thereof on which the control panel is disposed, the heat exchanger
faces the air inlet, and the fin pitch on an end portion of the
heat exchanger on a side of the control panel is the larger fin
pitch.
7. The air-conditioning apparatus of claim 2, wherein the heat
exchanger is divided into a plurality of heat exchanger portions in
a direction in which an air stream flows through the heat
exchanger, and in at least one of the plurality of divided heat
exchanger portions, the fin pitch of the heat exchanger portion
disposed on a downstream side is larger than the fin pitch of the
heat exchanger portion disposed on an upstream side.
8. The air-conditioning apparatus of claim 2, wherein the heat
exchanger is divided into a plurality of heat exchanger portions in
a direction in which an air stream flows through the heat
exchanger, and in at least one of the plurality of divided heat
exchanger portions, the fin pitch of the heat exchanger portion
disposed on an upstream side is larger than the fin pitch of the
heat exchanger portion disposed on a downstream side.
9. The air-conditioning apparatus of claim 2, wherein the heat
exchanger has a bent portion, and the fin pitch between adjacent
fins disposed at the bent portion is larger than the fin pitch
between adjacent fins disposed at a straight portion of the heat
exchanger.
10. The air-conditioning apparatus of claim 2, wherein the heat
exchanger has a bent portion, and the fin pitch between adjacent
fins disposed at a straight portion of the heat exchanger is larger
than the fin pitch between adjacent fins disposed at the bent
portion.
11. The air-conditioning apparatus of claim 2, wherein the housing
is provided with the air inlet formed in at least one side face
thereof and the air outlet formed in a top face thereof, the fan
includes a propeller fan and faces the air outlet, the heat
exchanger faces the air inlet and is divided into a plurality of
vertically aligned heat exchanger portions, and in at least one of
the plurality of divided heat exchanger portions, the fin pitch of
the heat exchanger portion disposed at a lower position is larger
than the fin pitch of the heat exchanger portion disposed at an
upper position.
12. The heat exchanger of claim 1, wherein the fins and the heat
transfer tubes are bonded to each other by one of brazing and
adhesion.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. national stage application of
PCT/JP2012/005041 filed on Aug. 8, 2012, the contents of which are
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a heat exchanger and an
air-conditioning apparatus having the same.
BACKGROUND
[0003] In the conventional heat exchangers for air-conditioning
apparatuses, a plate fin tube configuration is commonly used. The
plate fin tube configuration ensures close contact between fins and
heat transfer tubes, which is necessary to ensure a given heat
transfer performance of the heat exchangers, by stacking a
plurality of strip-shaped aluminum fins having circular holes with
a predetermined fin pitch between them, inserting a plurality of
copper or aluminum heat transfer tubes having a circular
cross-section into the stacked fins (to be also referred to as a
group of fins hereinafter) in the direction in which the fins are
stacked, and then increasing the inner diameter of the heat
transfer tubes by using a hydraulic or mechanical tube expander
(see, for example, Patent Literature 1).
[0004] In order to increase the contact area of the fins and the
heat transfer tubes, cylindrical collars are formed on each of the
edges of the circular holes of the fins by burring. Further, slits
may be formed in the flat portions of the fins between the circular
holes so as to improve the heat exchange performance between the
fins and the air flowing between the fins. Circular holes, collars
and slits are sequentially formed on the fin by placing a
progressive die having a plurality of processes on a press machine,
and operating the press machine continuously while supplying a
strip-shaped aluminum hoop (see, for example, Patent Literature 2).
After the circular holes, collars and slits are formed on the hoop
by press working, the fins are formed by cutting the hoop into
strips with a desired length.
[0005] Then, a predetermined number of fins are stacked with the
collars being in contact with the adjacent fins. After that, a
plurality of long heat transfer tubes having a U-shaped portion
called a hair pin are inserted into the fins and expanded. Since
both stacking of the fins and insertion of the circular tubes are
performed by using the collars as a reference, the fins are stacked
and fixed with an equal interval of the height of the collar (see,
for example, Patent Literature 3). A plurality of heat transfer
tubes are connected by brazing at their end portions to U-bends,
which are bent in a U shape and serve as circular pipes for pipe
connection, and components such as a distributor so that a
continuous refrigerant flow passage which has a plurality of folded
portions is formed in a group of fins. The group of fins including
the heat transfer tubes with the pipes connected at their end
portions may be formed in an L shape or a U shape. In forming, for
example, a U-shaped heat exchanger, the group of fins are bent in
an L shape twice, and accordingly, the heat exchanger having a
group of fins with a U-shaped overall structure and heat transfer
tubes with a U-shaped internal structure is formed (see, for
example, Patent Literature 4). Even in the heat exchanger after the
bending, the fins remain the same on its three faces (straight
portions) forming the U-shaped structure as before bending, and are
stacked with a constant interval of the height of the collar.
[0006] Recently, in air-conditioning apparatuses, in light of
increasingly serious energy issues, intense competition takes place
in terms of energy saving and cost reduction. Accordingly, for the
above-described heat exchanger, the shapes of heat transfer tubes
and fins, the fin pitch, and the materials of heat transfer tubes
and fins are still under study for improvements. Further, measures
have also been proposed to change the fin pitch depending on the
internal structure of the air-conditioning apparatus (see, for
example, Patent Literatures 5, 6 and 7).
PATENT LITERATURE
[0007] Patent Literature 1: Japanese Examined Patent Application
Publication No. 58-13249 (pages 3 & 4, FIGS. 1-3) [0008] Patent
Literature 2: Japanese Examined Patent Application Publication No.
58-9358 (pages 2 & 3, FIGS. 1-5) [0009] Patent Literature 3:
Japanese Examined Patent Application Publication No. 3-80571 (page
9, FIGS. 1 & 2) [0010] Patent Literature 4: Japanese Patent No.
4417620 (page 15, FIG. 20) [0011] Patent Literature 5: Japanese
Unexamined Patent Application Publication No. 63-233296 (page 2)
[0012] Patent Literature 6: Japanese Unexamined Patent Application
Publication No. 2004-245531 (page 3) [0013] Patent Literature 7:
Japanese Unexamined Patent Application Publication No. 2008-8541
(page 7, FIG. 3)
[0014] As described above, conventional heat exchangers are
manufactured by a process of stacking a plurality of fins on which
the collars are formed on the edges of the circular holes, and a
process of inserting the heat transfer tubes having a circular
cross-section into the circular holes of the stacked fins, and
expanding the heat transfer tubes. As a result, the pitch between
adjacent fins in the conventional heat exchangers is constant as
the height of the collar formed by burring. It is, therefore,
difficult to change the fin pitch in a partial area in the
conventional heat exchangers, in accordance with the internal
structure or the like of the air-conditioning apparatus to improve
the performance of the air-conditioning apparatus. Accordingly, the
air-conditioning apparatus having the conventional heat exchanger
has a problem that the cost is expensive with respect to the heat
exchanger performance.
[0015] For example, the outdoor unit of the air-conditioning
apparatus accommodates accommodation objects such as a compressor
cover (a cover which accommodates the compressor) and a control
panel. Accordingly, the air flow resistance in the heat exchanger
varies depending on the positions of the accommodation objects.
However, it is difficult for the conventional heat exchanger to
change the fin pitch in a partial area of the heat exchanger, in
accordance with the air flow resistance at different positions of
the heat exchanger, since the fin pitch is defined by the height of
the collar.
[0016] Note that a configuration for changing the fin pitch in a
partial area of the heat exchanger has also been proposed by, for
example, dividing the heat exchanger or using fins of different
collar heights. However, in order to form a heat exchanger with
such a configuration, a plurality of types of progressive dies for
the fins need to be prepared in accordance with the height of the
collar. Alternatively, a die having a mechanism for accommodating
the burring heights is required. As a result, when a plurality of
types of dies are provided, the cost of dies is expensive or the
manufacturing cost of the fins is expensive because of a
complicated process of replacing the dies. Further, when a die
having a mechanism for accommodating the burring heights is used,
the costs of the die and the press machine are expensive since the
die is complicated and large, and thus the press machine is large.
In addition, assembling a heat exchanger having such a
configuration costs a lot since fins having different collar
heights need to be stacked at predetermined positions. Further, due
to a practical limit defined by constraints of the die size or the
like, only two or three types of fins having different collar
heights can be used. Accordingly, it is practically difficult to
form a heat exchanger having such a configuration.
[0017] Alternatively, in order to avoid such a problem, a method
for manufacturing a heat exchanger by using a collar having a
height lower than the fin pitch (stacking interval) and not
stacking fins with reference to the collar height is also possible.
However, in manufacturing a conventional heat exchanger by this
method, in the conventional heat exchanger in which heat transfer
tubes having a circular cross-section are inserted into circular
holes defined in fins, there is a problem that each fin is set at a
wrong position when the heat transfer tubes are inserted into a
group of fins stacked with a predetermined fin pitch between them,
and a desired fin pitch between adjacent fins cannot be formed.
Therefore, when the conventional heat exchanger is manufactured by
this method, each fin needs to be mounted one by one on the heat
transfer tubes. However, in mounting the fins one by one on the
heat transfer tubes to manufacture a conventional heat exchanger,
it is necessary to insert the heat transfer tubes into the circular
holes of each fin, and move the fins in a long stroke in the axial
direction of the heat transfer tube to a desired position.
Alternatively, it is practically difficult to manufacture a
conventional heat exchanger by using a collar having a height lower
than the fin pitch (stacking interval) and not stacking the fins
with reference to the collar height.
SUMMARY
[0018] The present invention has been made to solve the
above-mentioned problem, and has as its first object to provide a
heat exchanger in which the fin pitch of a partial area can be
changed without increasing the costs of a die for the fin, a press
machine and assembly. The second object of this invention is to
provide an energy saving and low-cost air-conditioning apparatus
including the aforementioned heat exchanger, which costs little in
terms of heat exchanger performance.
[0019] A heat exchanger according to the present invention includes
a plurality of fins stacked with a predetermined fin pitch
therebetween, and a plurality of heat transfer tubes which are
disposed with a predetermined pitch therebetween in a longitudinal
direction of the fins and extend through the fins in the direction
in which the fins are stacked, wherein each of the plurality of
heat transfer tubes has a flat cross-sectional shape, each of the
plurality of fins includes a plurality of notches conforming to the
cross-sectional shape of each heat transfer tube on an end portion
of each fin in the longitudinal direction, each of the plurality of
notches includes a collar formed on an edge thereof, the heat
transfer tubes are respectively inserted into the notches, the
plurality of fins include one set of fins having a fin pitch larger
than a fin pitch of another set of fins, and the larger fin pitch
is larger than at least a height of the collar corresponding to an
amount of extension of the collar from a plate surface of the
fin.
[0020] An air-conditioning apparatus according to the present
invention includes a housing which is provided with an air inlet
and an air outlet, the heat exchanger according to the present
invention as disposed in the housing, and a fan disposed in the
housing.
[0021] The heat exchanger according to the present invention has
notches formed in the end portion of the fins in the longitudinal
direction so that the heat transfer tubes are inserted into the
notches. The fins can be mounted on the heat transfer tubes from
the side face of the heat transfer tubes, and the fins can be
mounted at a desired position by an end stroke. Accordingly, the
heat exchanger can be manufactured without inserting the heat
transfer tubes into a group of fins formed of the stacked fins
which uses collars as a reference. That is, the fins having the
same shape which do not require an expensive die or a press machine
can be mounted at a desired position on the heat transfer tubes
without labor of assembly. Accordingly, the heat exchanger in which
the fin pitch of a partial area can be changed without increasing
the cost of a die for the fin, the cost of press machine and the
cost of assembly can be provided.
[0022] Since the air-conditioning apparatus according to the
present invention includes the heat exchanger according to the
present invention, the fins can be effectively distributed compared
with the conventional device by changing the fin pitch of a partial
area of the heat exchanger depending on the internal structure of
the air-conditioning apparatus or the like (for example, by
increasing the fin pitch of the area in which the air volume is
smaller than the other area due to the presence of accommodation
objects). Accordingly, the heat exchange efficiency can be improved
with regard to the cost to performance ratio, and an energy saving
and low-cost air-conditioning apparatus can be provided. Further,
when the configuration of the present invention is applied to the
air-conditioning apparatus which has a conventional performance and
works without problem, the number of fins which becomes excessive
due to the improvement in performance can be reduced, thereby
allowing the size and price of the air-conditioning apparatus to be
reduced while ensuring the same performance.
BRIEF DESCRIPTION OF DRAWINGS
[0023] FIG. 1 is a perspective view of an outdoor unit according to
Embodiment 1 of the present invention.
[0024] FIG. 2 is a perspective view of an exemplary internal
structure of the outdoor unit according to Embodiment 1 of the
present invention.
[0025] FIG. 3 is a schematic view for explaining a compressor cover
adjacent area in the outdoor unit according to Embodiment 1 of the
present invention.
[0026] FIG. 4 is a graph showing the correlation between "an air
volume Q in the compressor cover adjacent area 5" and "a ratio L/D
of a distance L between the compressor cover adjacent area 5 and
the compressor cover 7 to a diameter D of a propeller fan 9" in the
outdoor unit according to Embodiment 1 of the present
invention.
[0027] FIG. 5 is a graph showing the correlation between the fin
pitch of the compressor cover adjacent area and the coefficient of
performance of the outdoor unit according to Embodiment 1 of the
present invention.
[0028] FIG. 6 is a schematic view for explaining the shape of
components of the heat exchanger and a manufacturing method of the
heat exchanger in the outdoor unit according to Embodiment 1 of the
present invention.
[0029] FIG. 7 is a sectional plan view showing the heat exchanger
and a control panel 8 in the outdoor unit according to Embodiment 2
of the present invention as seen from the perspective of the
propeller fan.
[0030] FIG. 8 is a perspective view of an exemplary internal
structure of the outdoor unit according to Embodiment 2 of the
present invention.
[0031] FIG. 9 is a sectional plan view showing the heat exchanger
in the outdoor unit according to Embodiment 3 of the present
invention as seen from the perspective of the propeller fan.
[0032] FIG. 10 is a sectional plan view showing the heat exchanger
in the outdoor unit according to Embodiment 4 of the present
invention as seen from the perspective of the propeller fan.
[0033] FIG. 11 is a graph showing the relationship between the
temperature efficiency .epsilon. and the heat exchanger performance
AK.
[0034] FIG. 12 is a front view showing the positions of densely and
sparsely arranged fins of the heat exchanger in the outdoor unit of
the air-conditioning apparatus according to Embodiment 5 of the
present invention.
DETAILED DESCRIPTION
Embodiment 1
[0035] A heat exchanger according to Embodiment 1 is formed to have
a fin pitch that is larger in its partial area than in its other
area, using an assembly method which is different from the
conventional method and in which the fin pitch can be easily
changed. Further, an air-conditioning apparatus according to
Embodiment 1 includes the heat exchanger according to Embodiment 1
in which fins are positioned in an optimal density in accordance
with the internal structure of the housing, thereby allowing for
energy saving, cost reduction and price reduction while maintaining
the same performance as that of the conventional apparatus.
[0036] A heat exchanger according to Embodiment 1, a manufacturing
method of the heat exchanger according to Embodiment 1 and an
air-conditioning apparatus according to Embodiment 1 will be
described in detail below. The following description assumes, as
the air-conditioning apparatus according to Embodiment 1, an
outdoor unit on which the heat exchanger according to Embodiment 1
is mounted.
[0037] FIG. 1 is a perspective view of an outdoor unit according to
Embodiment 1 of the present invention. FIG. 2 is a perspective view
showing an exemplary internal structure of this outdoor unit. In
order to facilitate understanding of the configuration of the
outdoor unit according to Embodiment 1, FIG. 2 shows only
accommodation objects which occupy a large part of the inner space
of a housing and does not show accommodation objects such as
refrigerant pipes, four-way valves and other valves.
[0038] An outdoor unit 101 according to Embodiment 1 is used for an
industrial air-conditioning apparatus installed in buildings and
factories. The outdoor unit 101 and an indoor unit (not shown) form
a refrigeration cycle. The outdoor unit 101 accommodates
accommodation objects such as a heat exchanger 1, a propeller fan
9, a compressor cover 7 which accommodates a compressor, and a
control panel 8.
[0039] The housing 34 is formed by an almost square top face 35a,
an almost square bottom face 35b and pillars (pillar members) 36
which connect the four corners of each of the top face 35a and the
bottom face 35b. That is, the housing 34 is in an almost
rectangular parallelepiped with its four side faces open. Three of
the four open side faces serve as air inlets 34a. A grid member or
the like may be provided in the air inlets 34a to prevent the user
from inadvertently touching the heat exchanger 1 with, for example,
his or her hand. Further, an almost cylindrical projection is
formed on the top face of the housing 34. The top face and outer
periphery of the projection are open and serve as an air outlet
34b. The air outlet 34b is provided with a fan guard 38 that guides
air blown out from the air outlet 34b.
[0040] As described above, the housing 34 having the
above-mentioned configuration accommodates, for example, the heat
exchanger 1, the propeller fan 9, the compressor cover 7 which
accommodates the compressor, and the control panel 8.
[0041] The heat exchanger 1 is formed in a U shape, as viewed in a
plan view, to face the air inlet 34a which is open on its three
side faces. That is, in the outdoor unit 101, the heat exchanger 1
is open to the environment in a large part except for the pillars
36 and the grid member disposed in the air inlet 34a. The heat
exchanger 1 is divided into three heat exchanger portions
vertically aligned in stages (hereinafter, the three stages of heat
exchanger portions will be referred to, where necessary, as a first
stage heat exchanger 2, a second stage heat exchanger 3 and a third
stage heat exchanger 4 which are numbered in ascending sequence
from the top). Further, each of the first stage heat exchanger 2,
the second stage heat exchanger 3 and the third stage heat
exchanger 4 is divided into two columns of heat exchanger portions
in the direction in which an air stream flows through the heat
exchanger portions.
[0042] The above-described configuration of the heat exchanger 1 is
merely an example. For example, the first stage heat exchanger 2,
the second stage heat exchanger 3 and the third stage heat
exchanger 4 may be integrally formed as the heat exchanger 1. The
heat exchanger 1 may be formed as a single column heat exchanger.
Alternatively, the heat exchanger 1 may be formed in an L shape, as
seen in a plan view, when the air inlet 34a is formed in its two
adjacent side faces. The heat exchanger 1 need not necessarily be
formed to have a bent portion. The heat exchanger 1 may be formed
by combining the heat exchanger portions in a straight shape as
seen in a plan view. The details of the heat exchanger 1 (the
detailed configuration of fins and heat transfer tubes and a
manufacturing method of the heat exchanger 1) will be described
later.
[0043] The propeller fan 9 is disposed in the projection on the top
face 35a so that its circumferential portion faces the air outlet
34b. That is, the outdoor unit 101 according to Embodiment 1 is
configured to draw by suction the outside air from the air inlet
34a formed in the side faces of the housing 34 by rotating the
propeller fan 9, exchange heat between the drawn outside air and a
refrigerant in the heat exchanger 1, and blow the outside air after
heat exchange.
[0044] The compressor cover 7 and the control panel 8 are
surrounded by the heat exchanger 1, as viewed in a plan view. That
is, the compressor cover 7 and the control panel 8 are disposed in
the flow passage of the outside air in the housing 34. More
specifically, the compressor cover 7 is disposed in the lower
portion of the housing 34 and is surrounded by the heat exchanger
1, as viewed in a plan view. The control panel 8 is disposed in the
upper portion of the housing 34 and is surrounded by the heat
exchanger 1, as viewed in a plan view. Further, the control panel 8
faces a portion of the side face of the housing 34, other than the
air inlet 34a. This side face is covered by a panel 37.
[0045] In the outdoor unit 101 according to Embodiment 1, the
compressor cover 7 is adjacent to a part of the third stage heat
exchanger 4 of the heat exchanger 1 (the adjacent area will be
referred to as a compressor cover adjacent area 5 hereinafter). In
other words, in the outdoor unit 101 according to Embodiment 1, the
distance between the compressor cover adjacent area 5 of the third
stage heat exchanger 4 and the compressor cover 7 is equal to or
smaller than a predetermined distance. That is, in the heat
exchanger 1, the air flow resistance in the compressor cover
adjacent area 5 is higher than that in an area other than the
former area (to be referred to as a compressor non-adjacent area 6
hereinafter), and the air volume in the compressor cover adjacent
area 5 is smaller than that in the compressor non-adjacent area 6.
Accordingly, in the heat exchanger 1 of Embodiment 1, the fin pitch
of the compressor cover adjacent area 5 is larger than that of the
compressor non-adjacent area 6.
[0046] In the outdoor unit 101 according to Embodiment 1 in which
the heat exchanger 1 faces the air inlet 34a formed in the side
faces of the housing 34 and the propeller fan 9 faces the air
outlet 34b formed in the top face of the housing 34, it is
advantageous that in the heat exchanger 1, the fin pitch of the
compressor cover adjacent area 5 is larger than that of the
compressor non-adjacent area 6 when the distance between the
compressor cover adjacent area 5 of the third stage heat exchanger
4 and the compressor cover 7 is equal to or smaller than a
predetermined distance (to be described later).
[0047] FIG. 3 is a schematic view for explaining the compressor
cover adjacent area in the outdoor unit according to Embodiment 1
of the present invention. FIG. 3 is a sectional plan view showing
the third stage heat exchanger 4 and the compressor cover 7 as seen
from the perspective of the propeller fan 9.
[0048] As shown in FIG. 3, letting D be the diameter of the
propeller fan 9, and L be the distance between the compressor cover
adjacent area 5 and the compressor cover 7, the air volume takes
values, shown in FIG. 4, in various portions of the third stage
heat exchanger 4.
[0049] FIG. 4 is a graph showing the correlation between "an air
volume Q in the compressor cover adjacent area 5" and "a ratio L/D
of the distance L between the compressor cover adjacent area 5 and
the compressor cover 7 to the diameter D of the propeller fan 9" in
the outdoor unit according to Embodiment 1 of the present
invention. A rotation speed N of the propeller fan 9 is
constant.
[0050] As shown in FIG. 4, when L/D is 0.15 or less, it is found
that the air flow resistance in the compressor cover adjacent area
5 is high and the air volume Q in the compressor cover adjacent
area 5 is small. Accordingly, in the outdoor unit 101 according to
Embodiment 1 in which the heat exchanger 1 faces the air inlet 34a
formed in the side faces of the housing 34 and the propeller fan 9
faces the air outlet 34b formed in the top face of the housing 34,
it is advantageous that in the heat exchanger 1, the fin pitch of
the compressor cover adjacent area 5 is larger than that of the
compressor non-adjacent area 6 when L/D is 0.15 or less.
[0051] Further, when the heat exchanger 1 is configured to have a
fin pitch of the compressor cover adjacent area 5 larger than that
of the compressor non-adjacent area 6, the fin pitch of the
compressor cover adjacent area 5 is defined in, for example, the
following way.
[0052] FIG. 5 is a graph showing the correlation between the fin
pitch of the compressor cover adjacent area and the coefficient of
performance of the outdoor unit according to Embodiment 1 of the
present invention. The vertical axis in FIG. 5 represents the
coefficient of performance (COP) of the air-conditioning apparatus
which uses the outdoor unit 101. The horizontal axis in FIG. 5
represents the ratio k (=fp2/fp1) of a fin pitch fp2 of the
compressor cover adjacent area 5 to a fin pitch fp1 of the
compressor non-adjacent area 6.
[0053] As can be seen from FIG. 5, when k (=fp2/fp1)=1, that is,
when the fin pitch fp2 of the compressor cover adjacent area 5 is
the same as the fin pitch fp1 of the compressor non-adjacent area
6, the coefficient of performance (COP) of the air-conditioning
apparatus which uses the outdoor unit 101 is close to a maximum
value. Further, in a region with values of k close to k=1 (in which
the fin pitch fp2 is close to the fin pitch fp1), the variation of
the coefficient of performance (COP) is small regardless of a
change in fin pitch fp2. As k (=fp2/fp1) increases, that is, as the
fin pitch fp2 of the compressor cover adjacent area 5 becomes large
relative to the fin pitch fp1 of the compressor non-adjacent area
6, the coefficient of performance (COP) of the air-conditioning
apparatus which uses the outdoor unit 101 decreases. Accordingly,
in Embodiment 1, in order to prevent the coefficient of performance
(COP) of the air-conditioning apparatus which uses the outdoor unit
101 from excessively decreasing due to too large a fin pitch fp2 of
the compressor cover adjacent area 5, the coefficient of
performance (COP) of the air-conditioning apparatus which uses the
outdoor unit 101 is set to, for example, 95% or more of the
coefficient of performance (COP) of the air-conditioning apparatus
which uses the outdoor unit 101 when k (=fp2/fp1)=1
(1<k.ltoreq.b in FIG. 5).
Details of Heat Exchanger 1
[0054] Next, details of the heat exchanger 1 will be described.
[0055] FIG. 6 is a schematic view for explaining the shape of
components of the heat exchanger and a manufacturing method of the
heat exchanger in the outdoor unit according to Embodiment 1 of the
present invention.
[0056] The detailed configuration of the heat exchanger 1 will
first be described with reference to FIG. 6.
[0057] The heat exchanger 1 is implemented in a fin tube heat
exchanger including a plurality of fins 12 stacked with a
predetermined fin pitch between them, and a plurality of heat
transfer tubes 10 which are arranged in the longitudinal direction
of the fins 12 with a predetermined interval between them and
extend through the fins 12 in the direction in which the fins 12
are stacked.
[0058] The heat transfer tube 10 allows the refrigerant to flow
through it so that the refrigerant exchanges heat with the air
which flows through the gaps between adjacent fins 12. The heat
transfer tube 10 has a flat cross-sectional shape (for example, an
elliptical shape) and has an inner space divided by partitions into
a plurality of flow passages (holes). Each heat transfer tube 10 is
inserted into notches 13 of the fin 12 (to be described later) in
the longitudinal direction of the cross-sectional shape.
[0059] The fin 12 is implemented using, for example, an almost
rectangular plate. A plurality of notches 13 are formed in the end
portion of the fin 12 in the longitudinal direction with a
predetermined interval between them. As described above, the
notches 13 are portions where the heat transfer tubes 10 are
inserted and conform to the cross-sectional shape of the heat
transfer tubes 10. In Embodiment 1, the notch 13 is formed as a
U-shaped groove, and the opening width of its end portion is almost
the same as the width of the heat transfer tube 10 (that is, the
dimension of its cross-section in the widthwise direction).
Further, collars 14 which extend almost perpendicularly to the
plate surface of the fin 12 are formed on the edge of the notch 13
in order to increase the contact area of the fin 12 and the heat
transfer tube 10 and ensure a given bonding strength of the fin 12
and the heat transfer tube 10. Further, the height of the collar 14
(the amount of extension of the collar 14 from the plate surface of
the fin 12) is lower than at least the fin pitch of the compressor
cover adjacent area 5, which is larger than that of the compressor
non-adjacent area 6 of the heat exchanger 1. In addition, a
plurality of slits (not shown) are formed in the surface of the
fins 12 to be open in the direction in which an air stream flows
through the gaps between adjacent fins 12 (that is, the widthwise
direction of the fin 12). The formation of slits allows the
temperature boundary layer on the surface of the fins 12 to be
separated and updated, thereby improving the heat exchange
efficiency between the fins 12 and the air which flows through the
gaps between adjacent fins 12.
[0060] Moreover, according to various literatures, a heat exchanger
which uses a combination of fins and heat transfer tubes having a
flat cross-section and an inner space divided into a plurality of
flow passages have a capacity/performance ratio which is equal to
or higher than that of a conventional heat exchanger which uses a
combination of fins and heat transfer tubes having a circular
cross-section.
[0061] Next, a manufacturing method of the heat exchanger 1 will be
described.
[0062] The fin 12 of the heat exchanger 1 is manufactured by
cutting a thin plate (plate member) such as a thin aluminum plate
wound around a reel in a hoop. Specifically, first, a plurality of
pilot holes 15 are formed in the vicinities of the end portions of
the thin plate in the direction in which the thin plate is fed. The
thin plate is intermittently fed in a high speed press machine (see
an arrow 16 of FIG. 6 which indicates a thin plate feeding
operation) by a thin plate feeding mechanism of the high speed
press machine by using the pilot holes 15 (for example, by
inserting pins into the pilot holes 15). Further, the high speed
press machine is provided with a progressive die to sequentially
form opening holes on the thin plate as, for example, the notches
13, the collars 14, and the slits by press forming while the thin
plate is intermittently fed in the high speed press machine.
Accordingly, a series of fins 17, that is, a line of a plurality of
the fins 12 is formed on the thin plate fed from the high speed
press machine.
[0063] The series of fins 17 is separated by a cutting device,
provided downstream of the high speed press machine, into the
individual fins 12 (see an arrow 18 which indicates a cutting
operation). The thus separated fins 12 are mounted on the heat
transfer tubes 10 as follows.
[0064] Specifically, a manufacturing line of the heat exchanger 1
according to Embodiment 1 includes a table. A plurality of heat
transfer tubes 10 are disposed on the upper surface of the table
with a predetermined interval between them. The table is provided
with a feed mechanism which is formed by, for example, a servo
motor, a ball screw and a linear motion guide and is positioned by
a pitch feeding operation in the axial direction of the heat
transfer tube 10 (that is, the direction in which the fins 12 are
stacked) (see an arrow 21 of FIG. 6 which indicates a pitch feeding
operation). An insertion device which is formed by, for example, a
cam and a servo is disposed above the table. The insertion device
includes a holding mechanism that holds the fin 12 cut by the
cutting device, and a rotation mechanism that rotates the fin 12
held by the holding mechanism so that the opening ends of the
notches 13 face downwards.
[0065] Accordingly, when the insertion device holds the fin 12 cut
by the cutting device, rotates the fin 12 held by the holding
mechanism so that the opening ends of the notches 13 face
downwards, and lowers the fin 12 toward the table, the upper
portions of the heat transfer tubes 10 start to be inserted into
the notches of the fin 12 from the side of their opening ends, the
fin 12 is pushed until the bottom portions of the notches 13 come
into contact with the upper portions of the heat transfer tubes 10,
and the fin 12 is mounted on a plurality of heat transfer tubes 10
disposed on the table (see an arrow 19 of FIG. 6 which indicates a
movement and rotation operation of the fin 12). While the insertion
device repeats the mounting operation of the fin 12, that is, in
the duration after one fin 12 is mounted on the heat transfer tubes
10 and the next fin 12 is mounted on the heat transfer tubes 10,
the table is moved by a predetermined pitch in the axial direction
of the heat transfer tube 10 so that the fin 12 is mounted on the
heat transfer tubes 1 with a desired pitch from the last fin 12 as
mounted on the heat transfer tubes 10.
[0066] The above-mentioned cutting operation 18 for the fin 12, the
movement and rotation operation of the fin 12, and the pitch
feeding operation 21 of the heat transfer tubes 10 are sequentially
performed to follow the hoop feeding operation 16 of the high speed
press machine while synchronizing the insertion device and a feed
mechanism of the table with each other. A deviation in
synchronization of the high speed press machine and the insertion
device is reduced by sagging the thin plate in the supply passage
of the thin plate in an area on the upstream side of the high speed
press machine to provide a buffer of the material and changing the
number of press strokes while detecting the amount of sagging.
[0067] Further, the amount of pitch movement of the above-mentioned
pitch feeding operation 21 is set by a controller of the feed
mechanism. Specifically, a large pitch movement amount is set for a
group of fins 22 which forms the compressor cover adjacent area 5
with a small air volume in the heat exchanger 1. A small amount of
pitch movement is set for a group of fins 23 which forms the
compressor non-adjacent area 6 with a large air volume in the heat
exchanger 1. By stacking a necessary number of fins 12 with such a
pitch movement amount, a group of fins assembly portion 24
including the group of fins 22 stacked with a large fin pitch and
the group of fins 23 stacked with a small fin pitch is completed
(in FIG. 6, assembly is in progress).
[0068] The completed group of fins assembly portion 24 and the heat
transfer tubes 10 are fixed to each other by brazing in a furnace
by using a brazing material coated on the heat transfer tubes 10 in
advance. Alternatively, the completed fin assembly 24 and the heat
transfer tubes 10 are fixed to each other by bonding by using an
adhesive applied to the portions defining the gaps between the heat
transfer tubes 10 and the collars 14 of the fins 12. After that,
two stacked group of fins assembly portions 24 are connected to
pipes and bent in an L shape twice to form a U shape. Thus,
assembly of the heat exchanger 1 (the first stage heat exchanger 2,
the second stage heat exchanger 3, and the third stage heat
exchanger 4) is completed.
[0069] As described above, according to Embodiment 1, the heat
exchanger 1 (the first stage heat exchanger 2, the second stage
heat exchanger 3, and the third stage heat exchanger 4) in which
the fin pitch of the compressor cover adjacent area 5 is larger
than that of the compressor non-adjacent area 6 is manufactured by
positioning the heat transfer tubes 10 with a predetermined
interval between them and mounting each fin 12 on the heat transfer
tubes 10. Accordingly, unlike the conventional manufacturing method
in which the heat transfer tubes having a circular cross-section
are inserted into circular holes of the group of fins which is
stacked in advance with reference to collars, the manufacturing
method of the heat exchanger 1 according to Embodiment 1 needs
neither complicated dies to change the height of collars nor a
large press machine to change the fin pitch of a partial area of
the heat exchanger 1. Further, the manufacturing method of the heat
exchanger 1 according to Embodiment 1 can immediately change the
fin pitch to different values by simply changing the controller
command value of the pitch movement amount of the feed mechanism to
change the fin pitch of a partial area of the heat exchanger 1.
[0070] The manufacturing method of the heat exchanger 1 according
to Embodiment 1 is also different from the conventional
manufacturing method of the heat exchanger in which the collar has
a height lower than the fin pitch, and the fins are stacked without
using the collars as a reference (the manufacturing method in which
the heat transfer tubes are inserted into circular holes defined in
each fin and the fin is moved by a long stroke in the axial
direction of the heat transfer tube to a desired position). Since
the fin 12 can be mounted on the heat transfer tube 10 from its
side face, the stroke length after insertion of the heat transfer
tube 10 into the notch 13 of the fin 12 and before the end of
positioning of the fin 12 at a desired position can be shortened.
Accordingly, in the manufacturing method of the heat exchanger 1
according to Embodiment 1, the fin can be mounted at a desired
position on the heat transfer tube 10 with different fin pitches in
a high speed operation which can follow the punching speed of a
high speed press machine with a speed on the order of, for example,
hundreds of SPM (Strokes Per Minute).
[0071] Further, the heat exchanger 1 in the outdoor unit 101
according to Embodiment 1 is formed such that the fin pitch of the
compressor cover adjacent area 5 with a high air flow resistance
and a small air volume is larger than that of the compressor
non-adjacent area 6 with an air volume larger than that of the
compressor cover adjacent area 5. That is, in the heat exchanger 1,
the fin pitch of the area having a small air volume and a
coefficient of performance (COP) which is not significantly
affected by an increase in fin pitch. Accordingly, the heat
exchanger 1 can keep the heat exchange efficiency in terms of cost
performance higher than that of a heat exchanger having the same
total number of fins as that of the heat exchanger 1 and the fin
pitch between adjacent fins is the same in all fins. Therefore, it
is possible to keep both the energy consumption and the cost of the
outdoor unit 101 which includes the heat exchanger 1 lower than
those in the conventional case. Further, when the configuration of
the outdoor unit 101 according to Embodiment 1 is applied to an
outdoor unit which requires only the conventional performance, the
number of fins 12 which becomes excessive due to the improvement in
performance can be reduced, thereby reducing the size and price of
the outdoor unit while ensuring the same performance. The
manufacturing time can also be reduced since the number of inserted
fins is decreased.
[0072] In Embodiment 1, the fin pitch in a partial area (the
compressor cover adjacent area 5) of only the third stage heat
exchanger 4 is increased. However, when the compressor cover 7 is
elongated in the height direction, the fin pitches in partial areas
of the second stage heat exchanger 3 and the first stage heat
exchanger 2 which are disposed higher than the third stage heat
exchanger 4 may also be increased. Further, in Embodiment 1, the
heat exchanger 1 is divided into three stages of heat exchanger
portions (the first stage heat exchanger 2, the second stage heat
exchanger 3 and the third stage heat exchanger 4). However, the
heat exchanger 1 may be divided into two stages of heat exchanger
portions or four or more stages of heat exchanger portions. It is
needless to say that the above-mentioned effect can be achieved in
those configurations as well.
[0073] Although Embodiment 1 assumes the compressor cover 7 as an
accommodation object that increases the air flow resistance (that
is, an accommodation object disposed in the vicinity of the heat
exchanger 1), this is merely an example. When an accommodation
object other than the compressor cover 7 is disposed in the
vicinity of the heat exchanger 1, the above-mentioned effect can be
achieved by increasing the fin pitch of an area in the vicinity of
the accommodation object in the heat exchanger 1 to be larger than
that of the remaining area.
Embodiment 2
[0074] Embodiment 1 assumes, for example, that the fin pitch in the
compressor cover adjacent area 5 which is adjacent to the
compressor cover 7 is changed as an example of changing the fin
pitch of a partial area of the heat exchanger 1. However, the area
in which the fin pitch is changed is not limited to the compressor
cover adjacent area 5. In addition to or instead of the compressor
cover adjacent area 5, the fin pitch of the following areas of the
heat exchanger 1 may be changed. Configurations which will not
specifically be referred to in Embodiment 2 are the same as those
in Embodiment 1, and elements with the same functions or
configurations are denoted by the same reference numerals.
[0075] FIG. 7 is a sectional plan view showing the heat exchanger
and the control panel in the outdoor unit according to Embodiment 2
of the present invention as seen from the perspective of the
propeller fan.
[0076] Similarly to Embodiment 1, the control panel 8 is disposed
on one side face of the housing 34 of the outdoor unit 101
according to Embodiment 2. Since the control panel 8 generates heat
by operating the outdoor unit 101, the control panel 8 needs
cooling during the operation of the outdoor unit 101. Accordingly,
the outdoor unit 101 according to Embodiment 2 is configured to
cool the control panel 8 by using an air flow generated by the
action of the propeller fan 9.
[0077] In Embodiment 2, in order to improve the cooling effect of
the control panel 8, the fin pitch on the end portions of the heat
exchanger 1 located on the side of the control panel 8 is larger
than that in an area of the heat exchanger 1 other than these end
portions. Embodiment 2 also uses the heat exchanger 1 formed in a U
shape similarly to Embodiment 1. Accordingly, the fin pitch on two
end portions 25 of the U-shaped heat exchanger 1 is larger than
that in an area of the heat exchanger 1 other than the two end
portions 25.
[0078] How the cooling effect of the control panel 8 is improved by
setting the fin pitch on the two end portions 25 of the heat
exchanger 1 to be larger than that in an area of the heat exchanger
1 other than the two end portions 25 will be described below.
[0079] FIG. 8 is a perspective view of an exemplary internal
structure of the outdoor unit 101 according to Embodiment 2 of the
present invention. White arrows shown in FIG. 8 indicate an air
flow inside the outdoor unit 101. In order to facilitate
understanding of the air flow, accommodation objects other than the
heat exchanger 1 and the propeller fan 9 are not illustrated in
FIG. 8.
[0080] The air has the property of flowing along the wall surface.
Accordingly, as shown in FIG. 8, in the outdoor unit 101 according
to Embodiment 2 in which the heat exchanger 1 faces the air inlet
34a formed in the side faces of the housing 34 and the propeller
fan 9 faces the air outlet 34b formed in the top face of the
housing 34, the air which has passed through the heat exchanger 1
collects at the two end portions 25 of the heat exchanger 1 located
in the vicinity of the panel 37, flows upwards along the two end
portions 25 of the heat exchanger 1, and is exhausted from the air
outlet 34b through the propeller fan 9 on the top face of the
housing 34.
[0081] In this configuration, the volume of air flowing from the
two end portions 25 of the heat exchanger 1 can be set relatively
large and the volume of air flowing along the two end portions 25
of the heat exchanger 1 can thus be set relatively large by setting
the fin pitch at the two end portions 25 of the heat exchanger 1 to
be larger than that of an area of the heat exchanger 1 other than
the two end portions 25 to decrease the air flow resistance at the
two end portions 25. Accordingly, the cooling effect of the control
panel 8 can be improved by setting the fin pitch at the two end
portions 25 of the heat exchanger 1 to be larger than that in an
area of the heat exchanger 1 other than the two end portions
25.
[0082] Further, the amount of heat exchanged between the air which
flows through the two end portions 25 and the refrigerant which
flows through the heat exchanger 1 is decreased by increasing the
fin pitch on the two end portions 25 of the heat exchanger 1 to be
larger than the fin pitch of an area of the heat exchanger 1 other
than the two end portions 25. As a result, during cooling
operation, the temperature of the air which flows from the two end
portions 25 of the heat exchanger 1, that is, the temperature of
the air which flows along the two end portions 25 of the heat
exchanger 1 can be decreased. Accordingly, during cooling
operation, the cooling effect of the control panel 8 can be also
improved by decreasing the temperature of the air.
[0083] In the outdoor unit 101 according to Embodiment 2, the
control panel 8 is disposed on one side of the housing 34, and the
fin pitch on the end portions of the heat exchanger 1 located on
the side of the control panel 8 is formed to be larger than the fin
pitch of an area of the heat exchanger 1 other than these end
portions. Accordingly, the cooling air volume of the control panel
8 can be increased, thereby improving the cooling effect of the
control panel 8.
Embodiment 3
[0084] The example of changing the fin pitch of a partial area of
the heat exchanger 1 is not limited to those described in
Embodiments 1 and 2. In addition to at least one of the
configurations of Embodiments 1 and 2 or instead of them, the fin
pitch of the following areas of the heat exchanger 1 may be
changed. A configuration which is not specifically described in
Embodiment 3 is the same as that of Embodiment 1 or Embodiment 2,
and the identical functions or configurations are denoted by the
same reference numerals.
[0085] FIG. 9 is a sectional plan view showing the heat exchanger
in the outdoor unit according to Embodiment 3 of the present
invention as seen from the perspective of the propeller fan. The
white arrow in FIG. 9 indicates an air flow inside the outdoor unit
101.
[0086] The heat exchanger 1 according to Embodiment 3 is divided
into two rows of the heat exchanger portions in the direction in
which an air stream flows through the heat exchanger 1
(hereinafter, the heat exchanger portion disposed upstream in the
air flow direction will be referred to as an outer heat exchanger
1b and the heat exchanger portion disposed downstream in the air
flow direction is referred to as an inner heat exchanger 1a). The
fin pitch of the inner heat exchanger 1a which is part of the heat
exchanger 1 is formed to be larger than the fin pitch of the outer
heat exchanger 1b.
[0087] As shown in FIG. 9, the air which flows through the heat
exchanger 1 and is exhausted from the propeller fan 9 is first
flows through the outer heat exchanger 1b and then flows through
the inner heat exchanger 1a. Assuming that the temperature of the
refrigerant which flows through the heat exchanger 1 is constant,
the temperature of the air changes after heat exchange in the outer
heat exchanger 1b, and the temperature difference between the air
which flows from the outer heat exchanger 1b and the refrigerant
which flows through the heat exchanger 1 decreases. That is, the
temperature difference between the air which flows through the
inner heat exchanger 1a and the refrigerant which flows through the
heat exchanger 1 (that is, the inner heat exchanger 1a) is small,
and accordingly, the heat exchange amount becomes small.
[0088] Accordingly, in Embodiment 3, the fin pitch of the inner
heat exchanger 1a which has the heat exchange amount smaller than
the outer heat exchanger 1b is formed to be larger than that of the
outer heat exchanger 1b.
[0089] As described above, in the outdoor unit 101 having the
configuration of Embodiment 3, it is possible to reduce the size
and price of the outdoor unit 101 while maintaining the same
performance as that of the conventional device by decreasing the
insertion number of fins of the inner heat exchanger 1a which has a
small heat exchange amount and a low contribution to the heat
exchange.
[0090] In Embodiment 3, the heat exchanger 1 is divided into two
rows of the heat exchanger portions in the direction in which an
air stream flows through the heat exchanger 1. However, as a matter
of course, the heat exchanger 1 may be divided into three or more
rows of the heat exchanger portions in the direction in which an
air stream flows through the heat exchanger 1. In at least two of
those heat exchanger portions, when the fin pitch of the heat
exchanger portion disposed downstream is larger than that of the
heat exchanger portion disposed upstream, the effect of Embodiment
3 can be achieved.
[0091] Although Embodiment 3 assumes the outdoor unit 101 including
the heat exchanger 1 in which the inner heat exchanger 1a has a fin
pitch larger than that of the outer heat exchanger 1b, the outdoor
unit 101 may be equipped with a heat exchanger 1 in which the outer
heat exchanger 1b has a fin pitch larger than that of the inner
heat exchanger 1a. This configuration is particularly advantageous
when the outdoor unit 101 is installed in a cold climate
environment where frost is often formed.
[0092] When the conventional outdoor unit in which the same fin
pitch is used for the outer heat exchanger and the inner heat
exchanger is installed in a cold climate environment where frost is
formed on the heat exchanger, the larger amount of frost is formed
on the outer heat exchanger compared to the inner heat exchanger,
and the frost is unevenly distributed. Accordingly, there is a
problem that the air flow passage between the fins in the outer
heat exchanger is blocked at early time, and the heating
performance of the air-conditioning apparatus having the outdoor
unit is impaired. Since the air first flows through the outer heat
exchanger and then the inner heat exchanger, the larger amount of
frost is formed on the outer heat exchanger where an absolute
humidity of the air is high.
[0093] Accordingly, in a modification example of Embodiment 3, the
fin pitch of the outer heat exchanger 1b which has the larger frost
formation than the inner heat exchanger 1a is formed to be larger
than the inner heat exchanger 1a. With this configuration of the
heat exchanger 1, the frost is evenly distributed on the inner heat
exchanger 1a and the outer heat exchanger 1b, and blockage of the
air flow passage between the fins may be delayed, thereby improving
the heating performance of the air-conditioning apparatus which
includes the outdoor unit 101.
[0094] In the modification example of Embodiment 3, the heat
exchanger 1 is divided into two rows of the heat exchanger portions
in the direction in which an air stream flows through the heat
exchanger 1. However, as a matter of course, the heat exchanger 1
may be divided into three or more rows of the heat exchanger
portions in the direction in which an air stream flows through the
heat exchanger 1. In at least two of those heat exchanger portions,
the fin pitch of the heat exchanger portion disposed upstream may
be larger than that of the heat exchanger portion disposed
downstream. With this configuration, the frost is evenly
distributed on the heat exchanger 1, and blockage of the air flow
passage between the fins may be delayed, thereby improving the
heating performance of the air-conditioning apparatus which
includes the outdoor unit 101.
Embodiment 4
[0095] The example of changing the fin pitch of a partial area of
the heat exchanger 1 is not limited to those described in
Embodiments 1 to 3. In addition to at least one of the
configurations of Embodiments 1 to 3 or instead of them, the fin
pitch of the following areas of the heat exchanger 1 may be
changed. A configuration which is not specifically described in
Embodiment 4 is the same as that of Embodiments 1 to 3, and the
identical functions or configurations are denoted by the same
reference numerals.
[0096] FIG. 10 is a sectional plan view showing the heat exchanger
in the outdoor unit according to Embodiment 4 of the present
invention as seen from the perspective of the propeller fan.
[0097] The heat exchanger 1 according to Embodiment 4 is formed in
a U shape as seen in a plan view. That is, the heat exchanger 1 is
formed of two bent portions 29 and three straight portions 30 (a
portion of the heat exchanger which is in a straight shape as seen
in a plan view). In the heat exchanger 1 according Embodiment 4,
the fin pitch of the bent portion 29 and the fin pitch of the
straight portion 30 are different.
[0098] In a bending process of the heat exchanger 1, the fin 12 of
the bent portion 29 may fall down or buckle. In this case, the fin
pitch of the bent portion 29 of the heat exchanger 1 may be formed
larger than the fin pitch of the straight portion 30 so as to
achieve the air flow volume of the bent portion 29 even if the end
portions of the fin 12 falls down or buckles during the bending
process. Alternatively, the fin pitch of the bent portion 29 of the
heat exchanger 1 may be formed smaller than the fin pitch of the
straight portion 30, that is, the number of stack of the fins in
the bent portion 29 may be increased so as to decrease the stress
applied to each fin 12 during the bending process, thereby
preventing the fin 12 from falling down or buckling and achieving
the air flow volume of the bent portion 29.
[0099] As described above, with the configuration of the heat
exchanger 1 of Embodiment 4, the air flow volume of the bent
portion 29 may be achieved and heat exchange can be effectively
performed at the bent portion 29. Accordingly, the heat exchange
efficiency of the heat exchanger 1 can be improved, and the energy
saved and small sized outdoor unit 101 may be provided.
[0100] Further, the following effect can also be achieved by
increasing the fin pitch of the bent portion 29 of the heat
exchanger 1 to be larger than the fin pitch of the straight portion
30.
[0101] In the heat exchanger 1 formed in a U shape as seen in a
plan view, the fin pitch between adjacent fins 12 located on the
inner side of the bent portion 29 is smaller than the fin pitch
between adjacent fins 12 located on the outer side of the bent
portion 29. Further, the pillars 36 are disposed on the outer
circumferential side of the bent portion 29 (see FIG. 1). As a
result, the air flow volume of the bent portion 29 becomes smaller
than that of the straight portion 30, which causes a distribution
of temperature efficiency of the bent portion 29 and the straight
portion 30 (the bent portion 29 and the straight portion 30 are
different in temperature efficiency). Specifically, in the
conventional heat exchanger which is formed by bending, in a U
shape as seen in a plan view, a heat exchanger having a uniform fin
pitch, the difference in temperature efficiency between the bent
portion and the straight portion is larger than that of the heat
exchanger 1 according to Embodiment 4 in which the fin pitch of the
bent portion 29 of the heat exchanger 1 is formed larger than the
fin pitch of the straight portion 30.
[0102] With reference to FIG. 11, a temperature efficiency
.epsilon. and a heat exchanger performance AK will be
described.
[0103] FIG. 11 is a graph showing the relationship between the
temperature efficiency .epsilon. and the heat exchanger performance
AK. In FIG. 11, the temperature efficiency .epsilon. of the heat
exchanger 1 according to Embodiment 4 (the heat exchanger 1 in
which the fin pitch of the bent portion 29 of the heat exchanger 1
is formed larger than the fin pitch of the straight portion 30) is
shown as a black circle. Further, the temperature efficiency
.epsilon. of the conventional heat exchanger (the heat exchanger
which is formed by bending the heat exchanger having the uniformly
formed fin pitch in a U shape as seen in a plan view) is shown as a
white circle. The heat exchanger 1 according to Embodiment 4 and
the conventional heat exchanger have the same total number of
fins.
[0104] The temperature efficiency .epsilon. (=(heat exchanger
outlet air temperature-heat exchanger inlet air
temperature)/(refrigerant saturation temperature-heat exchanger
inlet air temperature)) tends to decrease as the air flow volume
increases (as the air flow speed increases). Accordingly, in both
the heat exchanger 1 according to Embodiment 4 and the conventional
heat exchanger, the temperature efficiency (.epsilon.2,
.epsilon.2') of the bent portion is higher than the temperature
efficiency (.epsilon.1, .epsilon.1') of the straight portion. When
focusing on the temperature efficiency of the straight portion, in
the heat exchanger 1 according to Embodiment 4 and the conventional
heat exchanger formed of the same number of fins, the heat
exchanger 1 according to Embodiment 4 in which the fin pitch of the
bent portion 29 of the heat exchanger 1 is formed larger than the
fin pitch of the straight portion 30 has the temperature efficiency
.epsilon.1' which is higher than the temperature efficiency
.epsilon.1 of the conventional heat exchanger. Further, when
focusing on the temperature efficiency of the bent portion, in the
heat exchanger 1 according to Embodiment 4 and the conventional
heat exchanger formed of the same number of fins, the heat
exchanger 1 according to Embodiment 4 in which the fin pitch of the
bent portion 29 of the heat exchanger 1 is formed larger than the
fin pitch of the straight portion 30 has the temperature efficiency
.epsilon.2 which is smaller than the temperature efficiency
.epsilon.2' of the conventional heat exchanger.
[0105] As shown in FIG. 11, the heat exchanger performance AK (heat
transfer performance) and the temperature efficiency .epsilon. have
a property that the temperature efficiency .epsilon. gradually
approaches 1 as the heat exchanger performance AK increases.
Consequently, in the straight portion which has a large air flow
volume, the temperature efficiency of the heat exchanger 1
according to Embodiment 4 is improved by the amount of
.epsilon.1'-.epsilon.1 since the fin pitch is smaller than that of
conventional heat exchanger. Further, in the bent portion which has
a small air flow volume, the temperature efficiency of the heat
exchanger 1 according to Embodiment 4 is decreased by the amount of
.epsilon.2'-.epsilon.2 since the fin pitch is larger than that of
conventional heat exchanger.
[0106] However, the temperature efficiency (.epsilon.1,
.epsilon.1') of the straight portion is smaller than the
temperature efficiency (.epsilon.2, .epsilon.2') of the straight
portion, and, as described above, the temperature efficiency
.epsilon. has a property that the temperature efficiency .epsilon.
gradually approaches 1 as the heat exchanger performance AK
increases. As a result, the improvement in temperature efficiency
(.epsilon.1'-.epsilon.1) of the heat exchanger of Embodiment 4 is
large, while the decrease in temperature efficiency
(.epsilon.2'-.epsilon.2) of the heat exchanger of Embodiment 4 is
significantly small.
[0107] That is,
(.epsilon.1'-.epsilon.1)>(.epsilon.2'-.epsilon.2) is
established.
[0108] Therefore, as shown in Embodiment 4, an average temperature
efficiency of the heat exchanger 1 according to Embodiment 4, that
is, the heat exchange efficiency of the entire heat exchanger 1 is
significantly improved by increasing the fin pitch of the bent
portion 29 having a high temperature efficiency .epsilon. and
decreasing the fin pitch of the straight portion 30 having a low
temperature efficiency .epsilon..
Embodiment 5
[0109] The example of changing the fin pitch of a partial area of
the heat exchanger 1 is not limited to those described in
Embodiments 1 to 4. In addition to at least one of the
configurations of Embodiments 1 to 4 or instead of them, the fin
pitch of the following areas of the heat exchanger 1 may be
changed. A configuration which is not specifically described in
Embodiment 5 is the same as that of Embodiments 1 to 3, and the
identical functions or configurations are denoted by the same
reference numerals.
[0110] FIG. 12 is a front view of an exemplary internal structure
of the outdoor unit according to Embodiment 5 of the present
invention. The accommodation objects other than the heat exchanger
1 and the propeller fan 9 are not illustrated in FIG. 12.
[0111] The heat exchanger 1 according to Embodiment 5 is divided
into three stages of vertically aligned heat exchanger portions
(the first stage heat exchanger 2, the second stage heat exchanger
3 and the third stage heat exchanger 4). The fin pitch 33 of the
third stage heat exchanger 4 is larger than the fin pitch 32 of the
second stage heat exchanger 3, and the fin pitch 32 of the second
stage heat exchanger 3 is larger than the fin pitch 31 of the first
stage heat exchanger 2.
[0112] In the outdoor unit 101 according to Embodiment 1 in which
the heat exchanger 1 faces the air inlet 34a formed in the side
faces of the housing 34 and the propeller fan 9 faces the air
outlet 34b formed in the top face of the housing 34, the air volume
varies depending on the distance from the propeller fan 9.
Specifically, the air volume which passes through the third stage
heat exchanger 4 is smaller than the air volume which passes
through the first stage heat exchanger 2. Accordingly, in
Embodiment 5, the fin pitch of the third stage heat exchanger 4
which has the heat exchange amount smaller than that of the first
stage heat exchanger 2 is formed to be larger than that of the
first stage heat exchanger 2.
[0113] As described above, it is possible to reduce the size and
price of the air-conditioning apparatus while maintaining the same
performance as that of the conventional apparatus by decreasing the
insertion number of fins of the third stage heat exchanger 4 which
has a small air volume and a low contribution to the heat
exchange.
[0114] Further, in Embodiment 5, the heat exchanger 1 is divided
into three stages of vertically aligned heat exchanger portions.
However, the heat exchanger 1 may be divided into two stages of
heat exchanger portions or four or more stages of heat exchanger
portions. In at least two of those heat exchanger portions, when
the fin pitch of the lower heat exchanger portion is formed to be
smaller than the fin pitch of the upper heat exchanger portion, the
effect of Embodiment 5 can be achieved.
[0115] In the above-mentioned Embodiments 1 to 5, the present
invention has been described by taking, as an example, the outdoor
unit 101 in which the air outlet 34b is formed in the top face of
the housing 34. However, the effect of Embodiments 1 to 5 can be
achieved by applying the present invention to the outdoor unit in
which the air outlet is formed in the side face of the housing.
[0116] In the above-mentioned Embodiments 1 to 5, the present
invention has been described by taking, as an example, the heat
exchanger 1 formed in a U shape as seen in a plan view. However,
any shape of the heat exchanger may be used and the effect of
Embodiments 1 to 5 can be achieved regardless of the shape of the
heat exchanger.
[0117] In the above-mentioned Embodiments 1 to 5, the present
invention has been described by taking, as an example, the outdoor
unit 101 which includes a single heat exchanger 1 (including a
plurality of heat exchanger portions). However, the effect of
Embodiments 1 to 5 can be achieved in the outdoor unit which
includes a plurality of heat exchangers 1.
[0118] In the above-mentioned Embodiments 1 to 5, the present
invention has been described by taking, as an example, the outdoor
unit 101 which includes a propeller fan 9. However, the effect of
Embodiments 1 to 5 can be achieved in the outdoor unit which
includes a fan other than the propeller fan 9.
[0119] In the above-mentioned Embodiments 1 to 5, the present
invention is applied to the outdoor unit 101. However, as a matter
of course, the present invention is also applicable to the indoor
unit.
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