U.S. patent application number 11/884701 was filed with the patent office on 2008-07-03 for top plate structure for high location installation type air conditioner.
Invention is credited to Jihong Liu.
Application Number | 20080159848 11/884701 |
Document ID | / |
Family ID | 37115004 |
Filed Date | 2008-07-03 |
United States Patent
Application |
20080159848 |
Kind Code |
A1 |
Liu; Jihong |
July 3, 2008 |
Top Plate Structure for High Location Installation Type Air
Conditioner
Abstract
A high location installation type air conditioner includes a
body casing (3) for accommodating a fan (5), a fan motor (9), and a
heat exchanger (4), and a top plate (32) forming a top surface of
the body casing (3) for suspending the fan (5), the fan motor (9),
and the heat exchanger (4). The top plate (32) includes a plurality
of radial reinforcing ribs extending from a central portion of the
top plate (32) at which the fan motor (9) is supported to a
peripheral portion of the top plate (32) at which the heat
exchanger (4) is supported. The plurality of reinforcing ribs
include a reinforcing rib (32a') protruding from a front surface of
the top plate (32) and a reinforcing rib (32a) protruding from a
rear surface of the top plate (32) to improve rigidity of the top
plate (32).
Inventors: |
Liu; Jihong; (Sakai-shi,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
37115004 |
Appl. No.: |
11/884701 |
Filed: |
April 7, 2006 |
PCT Filed: |
April 7, 2006 |
PCT NO: |
PCT/JP2006/307462 |
371 Date: |
August 20, 2007 |
Current U.S.
Class: |
415/108 |
Current CPC
Class: |
F24F 1/0047 20190201;
F24F 1/0007 20130101; F24F 13/082 20130101 |
Class at
Publication: |
415/108 |
International
Class: |
F01D 25/24 20060101
F01D025/24; F24F 1/00 20060101 F24F001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 13, 2005 |
JP |
2005-115994 |
Claims
1. A top plate structure for an air conditioner including a body
casing (3) for accommodating a fan (5), a fan motor (9), and a heat
exchanger (4), and a top plate (32) forming a top surface of the
body casing for suspending the fan (5), the fan motor (9), and the
heat exchanger (4), wherein the top plate (32) has a plurality of
radial reinforcing ribs extending from a central portion of the top
plate at which the fan motor (9) is supported to a peripheral
portion of the top plate at which the heat exchanger (4) is
supported, the top plate structure being characterized in that: the
plurality of reinforcing ribs include a reinforcing rib (32a')
protruding from a front surface of the top plate (32) and a
reinforcing rib (32a) protruding from a rear surface of the top
plate.
2. The top plate structure according to claim 1, characterized in
that the reinforcing rib (32a') protruding from the front surface
of the top plate (32) and the reinforcing rib (32a) protruding from
the rear surface are alternately arranged in a circumferential
direction of the top plate (32).
3. The top plate structure according to claim 1 or 2, characterized
in that the plurality of reinforcing ribs include a plurality of
long main reinforcing ribs (32a) and a plurality of short
sub-reinforcing ribs (34) arranged between the main reinforcing
ribs (32a), and the main reinforcing ribs protrude from one of a
front surface and a rear surface of the top plate (32) and the
sub-reinforcing ribs (34) protrude from the other one of the front
surface and the
4. The top plate structure according to claim 1, characterized in
that the reinforcing ribs (32a'), (32a), (34) each have a depth
that changes in a longitudinal direction of the reinforcing rib,
and the depth at two end portions of each reinforcing rib is less
than the depth between the two end portions.
5. The top plate structure according to claim 1, characterized in
that the top plate (32) has a plate thickness that is set in a
range of 0.6 to 0.7 mm.
6. The top plate structure according to claim 1, characterized in
that the reinforcing ribs (32a'), (32a), (34) each have a depth of
8.0 to 10.0 mm.
Description
TECHNICAL FIELD
[0001] The present invention relates to a top plate structure for a
high location installation type air conditioner.
BACKGROUND ART
[0002] An indoor unit for a high location installation type air
conditioner, such as an air conditioner concealed in or suspended
from a ceiling of a house, includes, for example, a metal top plate
forming a top surface of a cassette body casing. The air
conditioner is concealed in the ceiling or suspended from a lower
surface of the ceiling by suspending heavy objects such as a heat
exchanger, fan, and fan motor from the top plate and then
suspending the main body casing with suspension bolts or the
like.
[0003] FIGS. 22 to 24 show a ceiling concealed air conditioner as
one example of a high location installation type air conditioner.
As shown in FIGS. 22 to 24, the air conditioner includes an air
conditioner body 1, which is arranged in an upper part of an
opening 7 formed in a ceiling C, and a decorative panel 2, which is
attached to the body 1 to cover the opening 7. The body 1 has a
cassette body casing 3, in which a generally annular heat exchanger
4 is arranged. A fan (impeller) 5 and a fan motor 9 are arranged in
a central portion of the heat exchanger 4 in the body casing 3 in
such a manner that an air inlet side of the fan 5 faces downward
and an air outlet side of the fan 5 faces the side of the heat
exchanger 4. A bell mouth 6 made of synthetic resin is arranged at
the air inlet side of the fan 5 in the body casing 3.
[0004] The fan 5 is formed by a centrifugal fan having a large
number of blades 5b arranged between a hub 5b and a shroud 5c. A
drain pan 8 is arranged below the heat exchanger 4. An air outlet
passage 10 is formed around the periphery of the heat exchanger
4.
[0005] The body casing 3 is generally hexagonal and includes a side
wall 31 and a top plate 32. The side wall 31 is formed from a heat
insulating material. The top plate 32 covers an upper portion of
the side wall 31. The heat exchanger 4 includes a pair of opposing
open ends. A tube plate 11 is arranged on each open end of the heat
exchanger 4. The tube plates 11 are connected to each other by a
predetermined partition plate 12.
[0006] The top plate 32 of the body casing 3, the tube plates 11,
the partition plate 12, and a switch box 13 attached to a lower
surface of the bell mouth 6 are all formed from metal plates. As
shown in FIG. 24, the top plate 32 and the switch box 13 are fixed
to the top and bottom ends of the partition plate 12 by screws.
[0007] The bell mouth 6 has a recessed portion 14 for accommodating
the switch box 13. An opening 16 is formed in a top surface 14a of
the recessed portion 14. A switch box joint 15 formed on a lower
end portion of the partition plate 12 is arranged in the opening
16. Two mounting pieces 17, which project integrally from two sides
of an upper end portion of the partition plate 12, are connected to
the top plate 32. The mounting pieces 17 are fixed to the top plate
32 from under the top plate 32 by screws 18.
[0008] Two mounting pieces 19, which project integrally from two
sides of a lower end portion of the partition plate 12, are
connected to the lower ends of the two tube plates 11. A mounting
piece 15 connected to the switch box 13 is welded and fixed to an
intermediate position of the partition plate 12. Each mounting
piece 19 is fixed to the corresponding tube plate 11 from under the
tube plate 11 by a screw 20. Each mounting piece 15 includes an
L-shaped base portion 15a and a mounting portion 15b. The base
portion 15a is connected to the partition plate 12. The mounting
portion 15b extends downward from a distal end of the base portion
15a and is formed integrally with the base portion 15a. In a state
in which the mounting portion 15b is arranged in the recessed
portion 14 through the opening 16, each mounting piece 15 is fixed
to a top surface 13a of the switch box 13 by screws 21.
[0009] The air conditioner includes a drain pump 22, a float switch
23, a drain pump accommodation portion 24 in which the drain pump
22 is arranged, a partition plate 25 partitioning the drain pump
accommodation portion 24, and a lid 26 of the switch box 13.
[0010] The top plate 32 is hexagonal and shaped in correspondence
with the body casing 3 of the air conditioner body 1. The top plate
32 has a peripheral portion along which a hook-shaped rim portion
32c is formed. The rim portion 32c is for fitting the top plate 32
and a peripheral portion at the upper end of the body casing 3 with
each other.
[0011] The top plate 32 has a plurality of main reinforcing ribs
32a extending radially from a central portion 33 of the top plate
32 at which the fan 5 and the fan motor 9 are supported to a
peripheral portion of the top plate 32 at which the generally
annular heat exchanger 4 is supported. The main reinforcing ribs
32a are recessed in a downward direction. Each main reinforcing rib
32a has a predetermined width and a predetermined depth. Each main
reinforcing rib 32a includes an outer part defining a heat
exchanger support portion having a step portion 32b with a smaller
recess depth. The main reinforcing ribs 32a enable the top plate 32
to have the required levels of basic rigidity, strength,
deflection, and vibration characteristics.
[0012] The interval between the main reinforcing ribs 32a increases
toward the peripheral portion of the top plate 32. This made result
in the top plate 32 having insufficient rigidity and strength.
Accordingly, a plurality of sub-reinforcing ribs 34 are arranged
between the main reinforcing ribs 32a as shown in FIG. 24. The
shape and dimensions of the sub-reinforcing ribs 34 are determined
in accordance with the load that can be assumed to be applied to
the top plate 32.
[0013] This structure is designed to reduce the static deflection
of the top plate 32 to or below a fixed value and maintains the
primary natural vibration frequency of the top plate 32 to or above
a fixed value to avoid resonance caused by rotation of the fan
motor 9.
[0014] The top plate 32 further includes a reinforcing rib 33a,
which is triangular when viewed from above, arranged in at the
central portion 33 where the fan 5 and the fan motor 9 are
supported. This improves the rigidity, strength, deflection, and
vibration characteristics of the supporting portion of the fan 5
and the fan motor 9 (refer to patent document 1).
[0015] The supporting portion of the fan 5 and the fan motor 9
includes a circular groove formed in each corner of the reinforcing
rib 33a. The reinforcing rib 33a includes three fan motor mounting
portions a, b, and c formed in central portions of the circular
grooves. The fan motor 9 is suspended from and fixed to the fan
motor mounting portions a, b, and c by mount members 11, which
absorb vibrations, and a mounting bracket 9b. This rotatably
supports the fan 5 by means of a motor shaft 9a.
[0016] Patent Document 1: Japanese Laid-Open Patent Publication No.
11-201496
[0017] In recent years, the cost of the air conditioner is required
to be reduced from various perspectives. The cost of the top plate
32 used in the air conditioner is also required to be reduced. To
reduce the cost of the top plate 32, the plate thickness of the
entire the top plate 32 (for example, 0.8 mm) may be reduced (for
example, to about 0.7 to 0.6 mm) to reduce material cost and
facilitate formation of the ribs etc. However, reduction in the
plate width would lower the rigidity and strength of the top plate
32 and require measures for suppressing vibrations of the top plate
32 generated when driving of the fan.
[0018] A top plate formed with a lower plate thickness than the
existing plate decreases material cost and is easily deformed. This
enables the force that is required for pressing and forming the top
plate and facilitates formation of the top plate. However, when a
thinner top plate includes the radial reinforcing ribs of the
above-described conventional structure, the amount of static
deflection increases and the primary natural vibration frequency
resulting from rotation of the fan motor 9 decreases. As a result,
the top plate would not satisfy the design standards.
DISCLOSURE OF THE INVENTION
[0019] Accordingly, it is an object of the present invention to
provide a top plate structure for an air conditioner that enables a
top plate that is thin yet has the required rigidity, strength, and
vibration characteristics.
[0020] A first aspect of the present invention provides a top plate
structure for an air conditioner including a body casing for
accommodating a fan, a fan motor, and a heat exchanger. A top plate
forming a top surface of the body casing suspends the fan, the fan
motor, and the heat exchanger. The top plate has a plurality of
radial reinforcing ribs extending from a central portion of the top
plate at which the fan motor is supported to a peripheral portion
of the top plate at which the heat exchanger is supported. The
plurality of reinforcing ribs include a reinforcing rib protruding
from a front surface of the top plate and a reinforcing rib
protruding from a rear surface of the top plate.
[0021] With such a top plate structure, even if the top plate is
thinner than a conventional top plate, by optimally adjusting and
setting the quantity, the cross-sectional shape (diaphragm shape),
the depth, and the width of the reinforcing ribs, the top plate is
provided with the required levels of rigidity, strength,
deflection, and vibration characteristics. In particular, the
structure in which the reinforcing rib portions protrude in two
directions from the front surface and the rear surface of the top
plate substantially doubles the vertical wall height dimensions of
the top plate between the front and rear surfaces. This greatly
improves rigidity of the top plate against deflection. As a result,
the plate thickness of the top plate can be decreased, the
formation of the top plate is facilitated, and the manufacturing
cost of the top plate is decreased.
[0022] It is preferred that the reinforcing rib protruding from the
front surface of the top plate and the reinforcing rib protruding
from the rear surface are alternately arranged in a circumferential
direction of the top plate. This improves the supporting rigidity
of the top plate in a balanced manner throughout the entire top
plate and uniformly reduces the maximum deflection amount of the
top plate.
[0023] It is preferred that the plurality of reinforcing ribs
include a plurality of long main reinforcing ribs and a plurality
of short sub-reinforcing ribs arranged between the main reinforcing
ribs, and the main reinforcing ribs protrude from one of a front
surface and a rear surface of the top plate and the sub-reinforcing
ribs protrude from the other one of the front surface and the rear
surface of the top plate. This improves the supporting rigidity of
the top plate in a balanced manner throughout the entire top plate
and uniformly reduces the maximum deflection amount of the top
plate.
[0024] It is preferred that the reinforcing ribs each have a depth
that changes in a longitudinal direction of the reinforcing rib,
and the depth at two end portions of each reinforcing rib is less
than the depth between the two end portions. This further
effectively reduces the maximum deflection amount of the top plate
and further improves the resonance rotation speed of the top plate.
As a result, further reduction in the cost of the top plate
resulting from lower material cost can be expected.
[0025] It is preferred that the top plate has a plate thickness
that is set in a range of 0.6 to 0.7 mm. The material cost is
lowered and press formation is facilitated as the plate thickness
of the top plate 32 decreases. However, the strength and rigidity
of the top plate 32 decreases and the deflection characteristics
and vibration characteristics of the top plate 32 deteriorate as
the plate thickness of the top plate 32 decreases. The
sub-reinforcing ribs are effective in compensating for such a
situation. However, the top plate 32 would still require a certain
plate thickness.
[0026] In one aspect of the present invention, the plate thickness
of the top plate 32 may be reduced to a range of 0.6 to 0.7 mm,
which is less than the plate thickness of 0.8 mm of the
conventional top plate. This also ensures sufficiently support
rigidity for the top plate 32. Accordingly, the cost of the top
plate is effectively reduced through material cost reduction.
[0027] More specifically, this range of plate thickness (0.6 mm to
0.7 mm) is the optimal range of plate thickness that reduces
material cost, facilitates formation, and ensures the required
quality performance in view of the relationship between the plate
thickness of the conventional top plate and the reinforcing effect
of the reinforcing ribs.
[0028] It is preferred that the reinforcing ribs each have a depth
of 8.0 to 10.0 mm. In the prior art, the design standard requires
the maximum deflection of the top plate to be reduced to 1.31 mm or
less and the resonance rotation speed of the top plate to be
maintained at 742.0 rpm or higher. To satisfy the design standard
and to maintain robustness of the static and dynamic
characteristics of the top plate with respect to the depth of the
reinforcing ribs, the appropriate depth of each reinforcing rib is
8.0 to 10.0 mm.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] FIG. 1 is a bottom view showing a top plate structure on
which a heat exchanger is arranged in a high location installation
type air conditioner according to a first embodiment of the present
invention;
[0030] FIG. 2 is a bottom view showing the top plate structure
without the heat exchanger;
[0031] FIG. 3 is a front view showing the top plate;
[0032] FIG. 4 is a vertical cross-sectional view taken along line
4-4 in FIG. 2;
[0033] FIG. 5 is a horizontal cross-sectional view taken along line
5-5 in FIG. 2 showing the structure of a reinforcing rib portion as
an essential portion of the top plate;
[0034] FIG. 6 is a cross-sectional view of the top plate taken in a
longitudinal direction of ribs;
[0035] FIG. 7 is a bottom view showing a top plate structure of a
basic model having six ribs fabricated to check the top plate
characteristics;
[0036] FIG. 8 is a perspective view taken from a diagonally
downward direction showing a top plate structure of a first test
sample fabricated using the basic model of FIG. 6 (having six
reinforcing ribs) in which all the reinforcing ribs protrude from
only a rear surface of the top plate;
[0037] FIG. 9 is a bottom view of a top plate structure of a basic
model having eight ribs fabricated to check the top plate
characteristics;
[0038] FIG. 10 is a perspective view taken from a diagonally
downward direction showing a top plate structure of a second test
sample fabricated using the basic model of FIG. 9 (having eight
reinforcing ribs) in which all the reinforcing ribs protrude from
only a rear surface of the top plate;
[0039] FIG. 11 is a perspective view taken from a diagonally
downward direction showing a top plate structure of a third test
sample fabricated using the basic model of FIG. 9 (having eight
reinforcing ribs) in which the reinforcing ribs protrude from both
front and rear surfaces of the top plate;
[0040] FIG. 12 is a bottom view of a top plate structure of a basic
model having ten ribs fabricated to check the top plate
characteristics;
[0041] FIG. 13 is a perspective view taken from a diagonally
downward direction showing a top plate structure of a fourth test
sample fabricated using the basic model of FIG. 12 (having ten
reinforcing ribs) in which all the reinforcing ribs protrude from
only a rear surface of the top plate;
[0042] FIG. 14 is a perspective view taken from a diagonally
downward direction showing a top plate structure of a fifth test
sample fabricated using the basic model of FIG. 12 (having ten
reinforcing ribs) in which the reinforcing ribs protrude from both
front and rear surfaces of the top plate;
[0043] FIG. 15 is a bottom view of a top plate structure of a basic
model having twelve ribs fabricated to check the top plate
characteristics;
[0044] FIG. 16 is a perspective view taken from a diagonally
downward direction showing a top plate structure of a sixth test
sample fabricated using the basic model of FIG. 14 (having twelve
reinforcing ribs) in which all the reinforcing ribs protrude from
only a rear surface of the top plate;
[0045] FIG. 17 is a graph showing the relationship between the
quantity of ribs and the maximum deflection amount of top plates of
first, second, fourth, and sixth test samples on which radial ribs
are arranged only on one side of each top plate;
[0046] FIG. 18 is a graph showing the relationship between the
quantity of ribs and the resonance rotation speed of top plates of
first, second, fourth, and sixth test samples on which radial ribs
are arranged only on one side of each top plate;
[0047] FIG. 19 is a graph showing the relationship between the
depth of ribs and the maximum deflection amount of top plates of
test samples 3 and 5 on which radial ribs are arranged on both
sides of each top plate;
[0048] FIG. 20 is a graph showing the relationship between the
depth of ribs and the resonance rotation speed of top plates of
test samples 3 and 5 on which radial ribs are arranged on both
sides of each top plate;
[0049] FIG. 21 is a bottom view showing a top plate structure for a
high location installation type air conditioner according to a
second embodiment of the present invention;
[0050] FIG. 22 is a vertical cross-sectional view taken along line
22-22 of FIG. 24 showing an overall structure of a conventional air
conditioner;
[0051] FIG. 23 is a bottom view showing the conventional air
conditioner from which a decorative panel and a body casing are
removed and viewed from below; and
[0052] FIG. 24 is an exploded perspective view showing the
attachment position relationship between a top plate and a bell
mouth of the conventional air conditioner.
BEST MODE FOR CARRYING OUT THE INVENTION
[0053] FIGS. 1 to 6 show a top plate structure for a high location
installation type air conditioner according to a first embodiment
of the present invention.
[0054] A top plate 32 of the first embodiment is optimal for
application to a body casing 3 of a ceiling concealed air
conditioner (indoor unit) that is substantially the same as that of
the conventional example described with reference to FIGS. 22 to
24.
[0055] As shown in FIG. 4, the top plate 32 has a plate thickness
D.sub.4 set at 0.7 mm, which is smaller than a thickness of 0.8 mm
of a conventional top plate. As shown FIGS. 1 and 2, the top plate
32 is hexagonal and shaped in correspondence with the cassette body
casing 3 of the air conditioner. The top plate 32 has a peripheral
portion along which a hook-shaped rim portion 32c is formed to be
fitted with the peripheral portion of an upper end of the body
casing 3.
[0056] In the same manner as in the conventional system shown in
FIGS. 22 to 24, the top plate 32 has a central portion 33
supporting a fan 5 and a fan motor 9 and a peripheral portion
supporting a generally annular heat exchanger 4. As shown in FIGS.
4 and 5, the top plate 32 includes two different kinds of
reinforcing ribs, namely, a plurality of radially extending
reinforcing ribs 32a and a plurality of radially extending
reinforcing ribs 32a'. The reinforcing ribs 32a and 32a' extend
from the central portion 33 to the peripheral portion of the top
plate 32. The reinforcing ribs 32a and 32a' protrude alternately
from front and rear surfaces of the top plate 32. The reinforcing
ribs 32a and 32a' each have an inverted trapezoidal cross-sectional
shape and each have a bottom surface width W.sub.1, a top width
W.sub.2, a depth D.sub.2, and an inclination angle .theta..sub.2. A
heat exchanger support portion located on the outer end of each
reinforcing ribs 32a, among the reinforcing ribs 32a and 32a', has
a step portion 32b. The step portion 32b of each reinforcing rib
32a is recessed downward with a depth D.sub.3 smaller than the
depth D.sub.2 by a predetermined dimension.
[0057] The top plate 32 further has a reinforcing rib 33a having a
depth D.sub.1 arranged on a supporting portion for the fan 5 and
the fan motor 9 in the central portion 33. The depth D.sub.1 is
equal to the depth D.sub.2. The reinforcing rib 33a extends between
five fan motor support portions a to e, which enable supporting at
three points or four points, and is in contact with the fan motor
support portions a to e. The reinforcing rib 33a effectively
improves rigidity, strength, deflection, and vibration
characteristics of the supporting portion of the fan 5 and the fan
motor 9.
[0058] As shown in FIG. 1, heavy components including the heat
exchanger 4, the fan 5, and the fan motor 9 are attached to the top
plate 32 in the same manner as in the conventional structure.
[0059] As described above, the structure of the present embodiment
includes the radial reinforcing ribs 32a' and 32a extending from
the central portion 33 of the top plate 32 on which the fan motor 9
is supported to the peripheral portion of the top plate 32 on which
the heat exchanger 4 is supported. The reinforcing ribs 32a'
protrude from the front surface of the top plate 32, and the
reinforcing ribs 32a protrude from the rear surface of the top
plate 32.
[0060] With this top plate structure, even when the top plate 32 is
formed to have a smaller plate thickness than the conventional top
plate, by optimally adjusting and setting the quantity and the
cross-sectional shape (diaphragm shape) of the reinforcing ribs
32a' and 32a in a wide range, the top plate 32 may be improved to
the required levels for rigidity, strength, deflection
characteristics, vibration characteristics, and the like. In
particular, the structure in which the reinforcing rib portions
protrude both from the front surface and the rear surface of the
top plate 32 substantially doubles the vertical wall height
dimensions of the top plate 32 between its front and rear surfaces
and greatly improves rigidity of the top plate 32 against
deflection. This structure reduces the plate thickness of the top
plate 32 and facilitates the formation of the top plate 32, thereby
reducing the manufacturing cost of the top plate 32.
[0061] Further, the reinforcing ribs 32a' protruding from the front
surface of the top plate 32 and the reinforcing ribs 32a protruding
from the rear surface of the top plate 32 are arranged alternately
in the circumferential direction. This structure improves the
supporting rigidity of the top plate 32 in a balanced manner
throughout the entire top plate 32 and uniformly reduces the
maximum deflection amount of the top plate 32 throughout the entire
top plate 32.
[0062] The reinforcing ribs 32a' and 32a are each formed to have a
depth h that changes so as to decrease as the two end portions in
the longitudinal direction (radial direction) become closer and
increase as the portion between the two end portions become closer.
When h1 represents the depth of the two end portions of each
reinforcing rib and h2 represents the depth of the intermediate
portion between the two end portions, h.sub.1<h.sub.2 is
satisfied.
[0063] In this manner, the depth of each of the reinforcing ribs
32a and 32a' changes in the longitudinal direction to have a
smaller depth in the two end portions and a larger depth in the
intermediate portion between the two end portions. This further
effectively reduces the maximum deflection amount of the top plate
32, improves the resonance rotation speed of the top plate 32, and
reduces the cost of the top plate 32 by lowering material cost.
[0064] In the present embodiment, the plate thickness of the top
plate 32 is set in the range of 0.6 to 0.7 mm. The material cost
for the top plate 32 decreases and press formation of the top plate
32 is facilitated as the plate thickness of the top plate 32
decreases. However, the strength and rigidity of the top plate 32
decreases and the deflection and vibration characteristics of the
top plate 32 deteriorate as the plate thickness of the top plate 32
decreases. The reinforcing ribs 32a' and 32a having the
above-described structure effectively prevent such characteristics
of the top plate 32 from deteriorating. However, the top plate 32
still needs to have a certain level of plate thickness.
[0065] Various experiments have been conduced from the viewpoints
described above. The experimental results indicate that the top
plate structure using the reinforcing ribs 32a' and 32a described
above enables the plate thickness of the top plate 32 to be reduced
to a range of 0.6 to 0.7 mm. The structure enables the top plate 32
with such reduced plate thicknesses to have sufficiently high
supporting rigidity and stable vibration characteristics. As a
result, the cost of the top plate 32 can be expected to be
effectively decreased by the lowered material cost.
[0066] This range of plate thickness is optimum for lowering the
material cost of the top plate 32, facilitating formation of the
top plate 32, and ensuring the required quality performance. This
plate thickness range is determined based on the relationship
between the plate thickness of the conventional top plate and the
reinforcing effect of the reinforcing ribs described above.
[0067] The top plate structure for the high location installation
type air conditioner according to the preferred embodiment enables
the top plate to have stable supporting rigidity, supporting
strength, and low-noise performance while reducing the thickness of
the top plate and reducing the cost of the top plate.
Test Examples
[0068] Analytical experiments described below verify the effect of
the radial reinforcing ribs 32a' and 32a protruding from the front
and rear surfaces of the top plate.
(1) Test Samples
[0069] First, four models of top plates that differ from one
another in the quantity of reinforcing ribs shown in FIG. 7 (six
ribs), FIG. 9 (eight ribs), FIG. 12 (ten ribs), and FIG. 15 (12
ribs) irrespective of the protruding direction of the ribs are used
as basic models. A top plate having ribs 32a arranged only on one
side and a top plate having ribs 32a' and 32a arranged on two sides
were prepared using each of the basic models of FIG. 9 (eight ribs)
and FIG. 12 (ten ribs). A top plate having ribs 32a arranged only
on one side was prepared using each of the basic models of FIG. 7
(six ribs) and FIG. 15 (twelve ribs). The six top plates 32A to 32F
of test samples 1 to 6 were prepared in total. All the top plates
32A to 32F have the plate thickness of 0.7 mm. Refer to Table 1 for
the specifications of the top plates 32A and 32F.
[0070] In Table 1, the root R (mm) indicates the radius of an arc
linking basal ends of a pair of adjacent reinforcing ribs.
TABLE-US-00001 TABLE 1 Sample No. 1 2 3 4 5 6 Quantity 6 8 8 10 10
12 Width W (mm) 60.0 Length L (mm) 696.0 Root R (mm) 81.0 39.0 39.0
20.0 20.0 9.5 Depth h One Side 9.5 6.0 -- 9.5 -- 9.5 (mm) Two Sides
-- -- 8.0 -- 9.5 --
[0071] a) First Top Plate 32A
[0072] As shown in FIG. 7, the first top plate 32A includes six
reinforcing ribs 32a that are arranged at equal intervals of 60
degrees in the circumferential direction. The dimension (length)
between the two distal ends of two opposing reinforcing ribs 32a
arranged at an interval of 180 degrees is 696.0 mm. Each
reinforcing rib 32a has a groove width W of 60.0 mm. The
reinforcing ribs 32a protrude from only either one of the front
surface and the rear surface of the top plate 32A (refer to FIG.
8).
[0073] b) Second Top Plate 32B
[0074] As shown in FIG. 9, the second top plate 32B includes eight
reinforcing ribs 32a that are arranged at equal intervals of 45
degrees in the circumferential direction. The dimension (length)
between the two distal ends of two opposing reinforcing ribs 32a
arranged at an interval of 180 degrees is 696.0 mm. Each
reinforcing rib 32a has a groove width W of 60.0 mm. The
reinforcing ribs 32a protrude from only either one of the front
surface and the rear surface of the top plate 32B (refer to FIG.
10).
[0075] (c) Third Top Plate 32C
[0076] As shown in FIG. 9, the third top plate 32C includes eight
reinforcing ribs 32a' and 32a that are arranged at equal intervals
of 45 degrees in the circumferential direction. The dimension
(length) between the two distal ends of two opposing reinforcing
ribs 32a' and 32a arranged at an interval of 180 degrees is 696.0
mm. Each of the reinforcing ribs 32a' and 32a has a groove width W
of 60.0 mm. The reinforcing ribs 32a' and 32a protrude alternately
from both the front surface and the rear surface of the top plate
32C (refer to FIG. 11).
[0077] d) Fourth Top Plate 32D
[0078] As shown in FIG. 12, the fourth top plate 32D includes ten
reinforcing ribs 32a that are arranged at equal intervals of 36
degrees in the circumferential direction. The dimension (length)
between the two distal ends of two opposing reinforcing ribs 32a'
and 32a arranged at an interval of 180 degrees is 696.0 mm. Each
reinforcing rib 32a has a groove width W of 60.0 mm. The
reinforcing ribs 32a protrude from only either one of the front
surface and the rear surface of the top plate 32D (refer to FIG.
13).
[0079] e) Fifth Top Plate 32E
[0080] As shown in FIG. 12, the fifth top plate 32E includes ten
reinforcing ribs 32a' and 32a that are arranged at equal intervals
of 36 degrees in the circumferential direction. The dimension
(length) between the two distal ends of two opposing reinforcing
ribs 32a' and 32a arranged at an interval of 180 degrees is 696.0
mm. Each of the reinforcing ribs 32a' and 32a has a groove width W
of 60.0 mm. The reinforcing ribs 32a' and 32a protrude alternately
from both the front surface and the rear surface of the top plate
32E (refer to FIG. 14).
[0081] f) Sixth Top Plate 32F
[0082] As shown in FIG. 15, the sixth top plate 32F includes twelve
reinforcing ribs 32a that are arranged at equal intervals of 30
degrees in the circumferential direction. The dimension (length)
between the two distal ends of two opposing reinforcing ribs 32a
arranged at an interval of 180 degrees is 696.0 mm. Each
reinforcing rib 32a has a groove width W of 60.0 mm. The
reinforcing ribs 32a protrude from only either one of the front
surface and the rear surface of the top plate 32F (refer to FIG.
16).
1) Influence of Quantity of Radial Ribs Arranged Only On One
Side
[0083] The influence of the quantity of ribs on the maximum
deflection amount and the resonance rotation speed of each top
plate 32 having the radial reinforcing ribs 32a protruding from
only one side are shown in Table 2 and the graphs in FIGS. 17 and
18. The reinforcing ribs 32a all have the same width W, length L,
and depth h.
TABLE-US-00002 TABLE 2 Rib Specifications Maximum Resonance
Rotation Speed Quantity Depth (mm) Deflection (mm) Primary
Secondary 6 9.5 1.60 784.0 990.0 8 9.5 1.35 907.0 990.0 10 9.5 1.32
914.0 940.0 12 9.5 1.41 890.0 917.0
[0084] The following findings were obtained from the analysis
results shown in Table 2 and the graphs in FIGS. 17 and 18.
[0085] The overall static characteristics and dynamic
characteristics of the top plate 32 including eight reinforcing
ribs 32a and the top plate 32 including ten reinforcing ribs 32a
are superior to the static and dynamic characteristics of the top
plate 32 including six reinforcing ribs 32a and the top plate 32
including twelve reinforcing ribs 32a.
[0086] The top plate 32 including eight reinforcing ribs 32a and
the top plate 32 including ten reinforcing ribs 32a have
substantially the same deflection amount (1.35/1.32 mm) and
substantially the same primary resonance rotation speed
(907.0/914.0 rpm). However, the top plate 32 including eight ribs
has the secondary resonance rotation speed of 990.0 rpm, and the
top plate 32 including ten ribs has the secondary resonance
rotation speed of 940.0 rpm, which is 5.0% lower than the secondary
resonance rotation speed of the top plate 32 including eight ribs.
The top plate 32 including eight reinforcing ribs 32a is assumed to
have the best static and dynamic characteristics.
2) Influence of Depth of Radial Ribs And Influence of Radial Ribs
Arranged On One Side Or Two Sides
[0087] The influence of the depth h of the radial ribs on the
maximum deflection amount and the resonance rotation speed of the
top plate 32 including eight radial reinforcing ribs protruding
from one side (32a) and the top plate 32 including radial
reinforcing ribs protruding from two sides (32a' and 32a) is shown
in Table 3 and the graphs in FIGS. 19 and 20.
TABLE-US-00003 TABLE 3 Resonance Rotation Speed Rib Maximum (rpm)
Specifications Deflection (mm) Primary Secondary Depth One Two Two
One Two One Quantity (mm) Side Sides Sides Side Sides Side 8 6.0
1.89 2.03 786.0 754.0 925.0 816.0 8.0 1.39 1.57 899.0 848.0 1033.0
915.0 9.5 1.16 1.35 970.0 907.0 1115.0 990.0 10 9.5 1.17 1.32 936.0
914.0 1061.0 940.0
[0088] The following findings are obtained from the analysis
results.
[0089] The top plates 32 having the single-side rib arrangement
(32a) and the double-side rib arrangement (32a' and 32a) both have
a smaller maximum deflection amount and a higher resonance rotation
speed as the depth of their ribs increases. This indicates that an
increase in the rib depth improves the static characteristics of
the top plates 32.
[0090] Table 3 and the graphs in FIGS. 19 and 20 show that the top
plates 32 having the double-side rib arrangement have better static
and dynamic characteristics than the top plates 32 having the
single-side rib arrangement.
[0091] The inventors of the present application further researched
changes in the maximum deflection amount and the resonance rotation
speed resulting from different rib depths of the top plate 32 when
using a plurality of parallel ribs in lieu of the radial ribs
described above. More specifically, the inventors measured the
maximum deflection amount and the resonance rotation speed of the
top plates 32 having a single-side rib arrangement of parallel ribs
and a double-side rib arrangement of parallel ribs.
[0092] The measurement results show that the maximum deflection
amount and the resonance rotation speed of the top plate 32 are
significantly affected by the rib depth when the depth of the
parallel ribs is 2.0 to 6.0 mm and relatively shallow. This
indicates that small differences in the rib depth greatly change
the maximum deflection amount and the resonance rotation speed of
the top plates 32 when the rib depth is relatively small. Thus,
robustness of the static and dynamic characteristics of the top
plates 32 with respect to the rib depth is low when the rib depth
is relatively small.
[0093] When the rib depth is 8.0 to 12.0 mm and relatively large,
the influence of the rib depth on the maximum deflection amount and
the resonance rotation speed of the top plates 32 decreases. This
indicates that small differences in the rib depth do not greatly
change the maximum deflection amount and the resonance rotation
speed of the top plate 32 when the rib depth is relatively large.
Thus, robustness of the static and dynamic characteristics of the
top plates 32 with respect to the rib depth is high when the rib
depth is relatively large.
[0094] When the rib depth is 14.0 to 18.0 mm and deep, the
influence of the rib depth on the maximum deflection amount and the
resonance rotation speed of the top plates 32 is limited. This
indicates that differences in the rib depth only slightly change
the maximum deflection amount and the resonance rotation speed of
the top plate 32 when the rib depth is large. Thus, robustness of
the static and dynamic characteristics of the top plates 32 with
respect to the rib depth is high when the rib depth is large.
[0095] These findings are also substantially applicable to top
plates including radial reinforcing ribs.
[0096] The design standard requires that the maximum deflection
amount of the top plate 32 be suppressed at 1.31 mm or less and
that the resonance rotation speed be maintained at 742.0 rpm or
higher.
[0097] The rib depth is preferably 8.0 to 10.0 mm to satisfy the
design standard while maintaining robustness of the static and
dynamic characteristics of the top plate 32 with respect to the rib
depth.
Second Embodiment
[0098] FIG. 21 shows a top plate structure for a high location
installation type air conditioner according to a second embodiment
of the present invention.
[0099] A top plate 32 of the second embodiment is also optimal for
application to a body casing 3 of a ceiling concealed air
conditioner (indoor unit) that is substantially the same as that in
the conventional example shown in FIGS. 22 to 24.
[0100] The top plate 32 is formed to have a plate thickness of
about 0.7 mm, which is smaller than the thickness of 0.8 mm of the
conventional top plate. The top plate 32 is hexagonal and shaped in
correspondence with the cassette body casing 3 of the air
conditioner shown in FIGS. 22 to 24. The top plate 32 has a
peripheral portion along which a hook-shaped rim portion 32c is
formed to be fitted with the peripheral portion of an upper end of
the body casing 3.
[0101] A fan 5 and a fan motor 9 identical to the structures shown
in FIGS. 22 to 24 are supported on a central portion 33 of the top
plate 32. A generally annular heat exchanger 4 is supported on the
peripheral portion of the top plate 32. In the same manner as in
the first embodiment, the top plate 32 includes a plurality of
radially extending main reinforcing ribs 32a extending from the
central portion 33 to the peripheral portion of the top plate 32.
The main reinforcing ribs 32a protrude from a rear surface of the
top plate 32. The main reinforcing ribs 32a each have an inverted
trapezoidal cross-section and each have a bottom surface width
W.sub.1, a top width W.sub.2, a depth D.sub.2, and an inclination
angle .theta..sub.2. A heat exchanger support portion located on
the outer side of each main reinforcing rib 32a has a step portion
32b. The step portion 32b is recessed downward with a depth D3 that
is smaller than the depth D.sub.2 by a predetermined dimension (the
dimension not shown).
[0102] The top plate 32 further has a reinforcing rib 33a having a
depth D.sub.1 arranged on a supporting portion for the fan 5 and
the fan motor 9 in the central portion 33. The depth D.sub.1 is
equal to the depth D.sub.2. The reinforcing rib 33a extends between
five fan motor support portions a to e, which enable supporting at
three points or four points, and is in contact with the fan motor
support portions a to e.
[0103] This structure effectively improves basic rigidity,
strength, deflection, and vibration characteristics of the
supporting portion of the fan 5 and the fan motor 9. However, the
interval between the main reinforcing ribs 32a in the peripheral
portion of the top plate 32 is large. As a result, the peripheral
portion of the top plate 32 may have insufficient rigidity,
strength, etc.
[0104] Therefore, the top plate 32 further has a plurality of
sub-reinforcing ribs 34 arranged between the main reinforcing ribs
32a as shown in the drawing. The shape and dimensions of the
sub-reinforcing ribs are determined in accordance with the load
assumed to be applied to the top plate 32. In the structure of the
present embodiment, the main reinforcing ribs 32a protrude from the
rear surface of the top plate 32, and the sub-reinforcing ribs 34
protrude from the surface opposite to the surface from which the
main reinforcing ribs 32a protrude.
[0105] This structure reduces the static deflection of the top
plate 32 to a fixed value or lower and maintains the primary
natural vibration frequency of the top plate 32 at a fixed value or
greater to avoid resonance caused by rotation of the fan motor
9.
[0106] Heavy components including the heat exchanger 4, the fan 5,
and the fan motor 9 are attached to the top plate 32 having the
above-described structure in the same manner as in the conventional
structure.
[0107] As described above, the plurality of reinforcing ribs in the
second embodiment include the long main reinforcing ribs 32a and
the short sub-reinforcing ribs 34 arranged between the long
reinforcing ribs 32a, and the main reinforcing ribs 32a protrude
from either one of the front surface and the rear surface of the
top plate 32, and the sub-reinforcing ribs 34 protrude from the
surface opposite the surface from which the main reinforcing ribs
32a protrude.
[0108] The structure having the sub-reinforcing ribs 32a also has
the same advantages as described in the first embodiment. This
structure improves the supporting rigidity of the top plate 32 in a
balanced manner throughout the entire top plate 32 and uniformly
reduces the maximum deflection amount of the top plate 32.
[0109] This structure also reduces the sufficient plate thickness
of the top plate 32 to 0.6 to 0.7 mm.
* * * * *