# Patent

## Title
Air conditioner

## Abstract

A centrifugal fan mounted in an air conditioner has the following relationship:

    
    
        outer diameter of a side plate of the centrifugal fan > outer diameter of the blade rear-edge part on side-plate side > diameter of the blade rear-edge part on main plate side ≧ outer diameter of the main plate. In the centrifugal fan, the blade rear-edge part is positioned inside from a straight line connecting the connection point between the blade rear-edge part and the main plate, to the connection point between the blade rear-edge part and the side plate, as viewed from the rotation axis. The blade rear-edge part has a shape such that the distance from the rotation axis becomes larger from the main plate toward the side plate.

## Background
TECHNICAL FIELD
The present invention relates to an air conditioner of which the body is installed in a space behind a ceiling and which performs cooling, heating, dehumidification, air cleaning, and humidification.
BACKGROUND ART
For example, in an air conditioner set forth in Patent Document 1, a ceiling surface suction port for sucking indoor air in a room into a space behind the ceiling, is provided in a position apart from the air conditioner body in the ceiling, and a body suction port is provided in a side wall of the body. A filter is arranged on the body suction port, and behind the body suction port, a heat exchanger is arranged so as to be opposed thereto. A blower is arranged in a space surrounded by an airflow guide plate and a ceiling panel. In the ceiling panel mounted under the body, a ceiling panel blowoff port is provided alone.
By such arrangements, since the ceiling surface suction port into which air in the room is sucked is spaced apart from the ceiling panel blowoff port, the short cycle phenomenon that a part of flow from the blowoff port is directly sucked into the suction port, is prevented from occurring, thereby allowing the indoor temperature to be uniformized. Furthermore, since the space behind the ceiling can be used as a flow path for sucked air, there is no need for a duct, so that it is possible to reduce costs of facilities and construction costs, and to decrease a flow path resistance. Moreover, if, as a blower, a centripetal fan is used instead of a centrifugal fan, the fan can be placed in a space surrounded by the heat exchanger, thereby allowing the airflow guide plate to be omitted.
[Patent Document 1] Japanese Patent No. 2706383
DISCLOSURE OF INVENTION
Problems to be Solved by the Invention
The conventional air conditioner is configured as described above. However, when a centrifugal fan in which the outer diameter of a main plate and that of a side plate is substantially the same is used for a blower, the direction of blowoff air from the centrifugal fan is a horizontal direction perpendicular to an axis, so that, when the centrifugal fan is installed within the air conditioner body, blowoff flow on the side-plate side and that on the main plate side interfere with each other to thereby enhance a draft resistance and increase noises. As a result, it is necessary for the fan to be installed so as to protrude downward from the air conditioner body. It is required, therefore, that the ceiling panel is installed in a state of protruding from the ceiling surface, which makes the size-reduction of the apparatus difficult.
If suction distance between a body top plate and the suction port of the centrifugal fan is too small, the draft resistance is increased, and due to the difference in flow speed between the vicinity of the baffle plate and the body top plate side, drifts occur, so that suction flow is disturbed increasing noises. On the other hand, if the above-described suction distance is too large, the body height becomes undesirably large.
In the case where the body and the ceiling panel are separate ones before installing, since the centrifugal fan is arranged in a state of protruding from the body, the centrifugal fan suffers damage during transportation. In addition, in order to prevent the damage thereto, a large amount of packing materials are needed around the fan protruding from the body, which is unfavorable to environment.
The present invention has been made in order to solve the problems as described above, and the object of the present invention is to obtain an air conditioner that is high in product reliability and handling properties during transportation, and low in noise, that gives no feeling of oppression to residents, and that can be packed with a small amount of packing materials, compared with conventional air conditioners.
Means for Solving the Problems
The air conditioner according to the present invention comprises: a body panel that is installed to be substantially flush with a ceiling of a room air-conditioned by the air conditioner, and has a blowoff port for air from the inside of an air conditioner body; a side wall installed in an upright position, along the outer periphery of the body panel; an air conditioner top plate provided so as to cover a surface of the side wall on the opposite side to the body panel; a body suction port formed in the side wall of the air conditioner body; a heat exchanger provided in the vicinity of the body suction port, a fan motor fixed to the air conditioner top plate; a centrifugal fan in which a convex-shaped boss part securely hung on a rotational shaft of the fan motor, a centrifugal fan for sucking the air sucked via the heat exchanger, and blowing off the air to the room; and an airflow guide plate for blowoff of the fan, which is installed so that the end part of the air blowoff side thereof is located at a higher position than that of the ceiling, wherein the centrifugal fan comprises: a main plate having a flat part provided on the outer peripheral side thereof, and the boss part provided at a central part thereof; a side plate having an airflow guide wall provided so as to surround the boss part with a predetermined distance therebetween; and a plurality of blades provided between the main plate and the side plate so as to be substantially orthogonal to a plane perpendicular to the rotation axis, and wherein, with the rotation of the plurality of blades, the centrifugal fan sends air from a suction port formed by a boss-side wall surface of the main plate and an end part of the side plate opposite to the boss-side wall surface, toward a blowoff port formed by the outer peripheral side flat part of the main plate and an end part of the side plate opposite to the outer peripheral side flat part; when an edge part of the blade positioned on the down stream side of a blowing direction is taken as a blade rear-edge part, the centrifugal fan has the following relationship: the outer diameter of the side plate>the outer diameter of the blade rear-edge part on side-plate side>the diameter of the blade rear-edge part on main plate side≧the outer diameter of the main plate; and the blade rear-edge part is positioned inside a straight line connecting the connection point between the blade rear-edge part and the main plate, and the connection point between the blade rear-edge part and the side plate, as viewed from the rotational axis side; and wherein the blade rear-edge part has a shape such that the distance from the rotational axis becomes larger from the main plate toward the side plate.
Advantages
According to the present invention, an air conditioner comprises:

    a body panel that is installed to be substantially flush with a ceiling of a room air-conditioned by the air conditioner, and has a blowoff port for air from the inside of an air conditioner body;
    a side wall installed in an upright position, along the outer periphery of the body panel; an air conditioner top plate provided so as to cover a surface of the side wall on the opposite side to the body panel; a body suction port formed in the side wall of the air conditioner body; a heat exchanger provided in the vicinity of the body suction port; a fan motor fixed to the air conditioner top plate; a centrifugal fan in which a convex-shaped boss part securely hung on a rotational shaft of the fan motor, a centrifugal fan for sucking the air sucked via the heat exchanger, and blowing off the air to the room; and an airflow guide plate for blowoff of the fan, which is installed so that the end part of the air blowoff side thereof is located at a higher position than that of the ceiling, wherein the centrifugal fan comprises: a main plate having a flat part provided on the outer peripheral side thereof, and the boss part provided at the central part thereof; a side plate having an airflow wall provided so as to surround the boss part with a predetermined distance therebetween; and a plurality of blades provided between the main plate and the side plate so as to be substantially orthogonal to a plane perpendicular to the rotation axis, and wherein, with the rotation of the plurality of blades, the centrifugal fan sends air from a suction port formed by a boss-side wall surface of the main plate and an end part of the side plate opposite to the boss-side wall surface, toward a blowoff port formed by the outer peripheral side flat part of the main plate and an end part of the side plate opposite to the outer peripheral side flat part; when an edge part of the blade positioned on the down stream side of a blowing direction is taken as a blade rear-edge part, the centrifugal fan has the following relationship: the outer diameter of the side plate> the outer diameter of the blade rear-edge part on side-plate side> the diameter of the blade rear-edge part on main plate side≧ the outer diameter of the main plate; and the blade rear-edge part is positioned inside a straight line connecting the connection point between the blade rear-edge part and the main plate, and the connection point between the blade rear-edge part and the side plate, as viewed from the rotational axis side; and wherein the blade rear-edge part has a shape such that the distance from the rotation axis becomes larger from the main plate toward the side plate. Therefore, an air conditioner can be obtained that is high in product reliability and transportability during transportation, and low in noise, that gives no feeling of oppression to residents, and that can be packed with a small amount of packing materials, compared with conventional air conditioners.





BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram showing an installation state of an example of an air conditioner according to a first embodiment of the present invention, as viewed from a room.
FIG. 2 is a longitudinal sectional view of the air conditioner in its installation state.
FIG. 3 is a perspective view of an air conditioner body and a ceiling panel at the time of installation.
FIG. 4 is a longitudinal sectional view of the air conditioner in FIG. 2.
FIG. 5 is a horizontal sectional view taken along section indicating lines k1 to k4 in FIG. 4.
FIG. 6 is a perspective view of an airflow guide plate.
FIG. 7 is a perspective view of a centrifugal fan as viewed from its main plate side.
FIG. 8 is a longitudinal section projection view corresponding to FIG. 7.
FIG. 9 shows a blade sectional view taken along a line a-a in FIG. 8, and its partially enlarged view.
FIG. 10 shows a blade sectional view taken along a line b-b in FIG. 8, and its partially enlarged view.
FIG. 11 is a diagram showing the change in the wall thickness of a blade section.
FIG. 12 is a diagram showing flow in the vicinity of blade step 13c in FIG. 9.
FIG. 13A is a diagram showing an outline of a molding method (first half).
FIG. 13B is a diagram showing an outline of a molding method (second half).
FIG. 14 is a graph showing the relationship between the ratio (E/H) of the distance E from a bell mouth 6a to a top plate 1c with respect to the body height H, and the noise value under the same air mount condition.
FIG. 15 is a perspective view, at the time of installation, of an air conditioner body and a ceiling panel of an air conditioner, according to a second embodiment of the present invention, the air conditioner being installed in a case where a room is elongate.
FIG. 16 is a longitudinal sectional view of the air conditioner taken along section indicating lines J1 to J3 in FIG. 14.
FIG. 17 is a horizontal sectional view at the height positions of L1-L2 and L3-L4 in FIG. 15, wherein the section at each of these two height positions is shown in a half in the illustration.
FIG. 18 is a perspective view, at the time of installation, of an air conditioner body and a ceiling panel of an air conditioner, according to a third embodiment of the present invention.
FIG. 19 is a longitudinal sectional view corresponding to FIG. 17.
FIG. 20 is a horizontal sectional view taken along section indicating lines k1 to k4 in FIG. 18.
FIG. 21 is a horizontal sectional view corresponding to FIG. 19 at the time when a heat exchanger is replaced with an air cleaning filter.
FIG. 22 is a horizontal sectional view corresponding to FIG. 19 at the time when a heat exchanger is replaced with a humidifying filter.
FIG. 23 is a longitudinal sectional view of a conventional ceiling-embedded air conditioner.



REFERENCE NUMERALS
1 air conditioner body
1a body side-plate side suction port
1b body side-wall
1c body top plate
1d body top plate side suction port
2 dust removal filter
2a air cleaning filter
2b humidifying filter
3 heat exchanger
3a additional heat exchanger
4 body panel
4a body panel blowoff port
4b central panel
4c body panel central opening
5 drain pan
6 airflow guide plate
6a bell mouth
6b airflow guide plate blowoff port
6c airflow guide part
7 fan motor
8 centrifugal fan
8a fan suction port
8b fan blowoff port
9 room
9a ceiling
9b space behind ceiling
10 ceiling suction port
11 side plate
11a side plate suction part
11b airflow guide wall
11c side plate recess part
11d side plate inner periphery front end part
12 main plate
12a boss
13 blade
13a blade front edge part
13b blade rear edge part
13c step formed by thickness difference between inner and outer peripheral side blade parts 13e and 13d at a blade dividing line B.
13d outer peripheral side blade part located on the outer peripheral side of the blade dividing line B
13e inner peripheral side blade part located on the inner peripheral side of the blade dividing line B
13as blade front-edge part side-plate side connection part
13bm blade rear-edge part main plate side connection part
13bs blade rear-edge part side-plate side connection part
13s warped line
14a and 14b molds
15 electrical component box
15a electrical substrate
16 humidification tank
200 air conditioner body
201 ceiling surface suction port
202 body side-wall
202a body suction port
203 filter
204 heat exchanger
205 airflow guide plate
206 blower
207 ceiling panel
207a ceiling panel blowoff port
208 ceiling
209 room
210 space behind ceiling
BEST MODES FOR CARRYING OUT THE INVENTION
First Embodiment
Hereinafter, an air conditioner according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 11.
FIG. 1 shows a diagram showing the air conditioner according to the first embodiment of the present invention, as its installation state is viewed from a room; FIG. 2 is a longitudinal sectional view of the air conditioner in the installation state; FIG. 3 is a perspective view of an air conditioner body and a ceiling panel at the time of installation; FIG. 4 is a longitudinal sectional view of the air conditioner in FIG. 2; FIG. 5 is a horizontal sectional view taken along section indicating lines k1 to k4 in FIG. 4; FIG. 6 is a perspective view of an airflow guide plate; FIG. 7 is a perspective view of a centrifugal fan as viewed from its main plate side; FIG. 8 is a longitudinal section projection view corresponding to FIG. 7; FIG. 9 shows a blade sectional view taken along a line a-a in FIG. 8, and its partially enlarged view; FIG. 10 shows a blade sectional view taken along a line b-b in FIG. 8, and its partially enlarged view; and FIG. 11 is a diagram showing the change in the wall thickness of a blade section.
As shown in FIGS. 1 and 2, at a position apart from a body panel 4 in a ceiling 9a, there is provided a ceiling suction port 10 for sucking indoor air in a room 9 to a space 9b behind the ceiling, and under an air conditioner body 1, the body panel 4 facing the ceiling 9a is opposed to the room 9. A body panel blowoff port 4a is formed into grid shape, and installed under the air conditioner body 1 so as to be substantially flush with the room-side surface of the ceiling 9.
As illustrated in FIG. 2 or 4, there are provided a body side-plate side suction port 1b formed on each surface of body side wall 1b of the air conditioner body 1, and a body top plate side suction port 1d formed in the body top plate 1c along the side wall 1b. A dust removal filter 2 is provided so as to completely cover the body-side plate side suction port 1a and the body top plate-side suction port 1d. Here, it is only necessary for the body-side plate side suction port 1a to have an opening in at least one surface of the body side-wall 1b. Also, if the body-side plate side suction port 1a has an opening, there is no need for a body top plate-side suction port 1d. 
As shown in FIGS. 4 and 5, inside the body side-wall 1b, a heat exchanger 3 in a substantially square shape is installed in an upright position, substantially along the body side plate side suction port 1a. A side plate 11 of a centrifugal fan 8 has a straight-pipe shape side plate suction port 8a constituting a fan suction port 8a, and an airflow guide wall 11b for guiding air that has been sucked inside a fan of the side plate 11, to the blowoff port. In the vicinity of the side plate 11, there is an airflow guide plate 6 provided so as to completely isolating a fan suction air path Ma from a blowoff air path Mb. The airflow guide plate 6 has a configuration in which a bell mouth 6a that is formed so as to cover a side plate suction part 11a plate suction part 11a substantially in parallel thereto and that is installed a predetermined distance apart from the body top plate 1c, is integrated into one unit with an air guide part 6c that is formed along the surface of the air guide wall 11b substantially in parallel thereto to guide a blowoff flow of the centrifugal fan 8 from the airflow guide plate blowoff port 6b to the outside of the air conditioner body via the blowoff port of the body panel 4. By virtue of the bell mouth 6a, the centrifugal fan 8 on the suction side does not become exposed, and the rotation of the centrifugal fan 8 does not affect air flow on the suction side, so that the flow on the suction side is rectified and air is efficiently sucked into the centrifugal fan 8. Furthermore, as shown in FIGS. 4 and 6, the airflow guide part 6c is configured so as to gradually enlarge from the fan blowoff port 8b toward the airflow guide plate blowoff port 6b into a truncated cone shape. The airflow guide plate 6 is arranged so as to be prevented from coming in contact with the centrifugal fan 8, and it is fixed to a drain pan 5, with screws or an adhesive. Alternatively, the airflow guide plate 6 may be formed integrally with the drain pan 5.
A fan motor 7 is provided to the body top plate 1c, and the rotational shaft of the fan motor 7 is securely inserted into a boss 12a of the centrifugal fan 8. The centrifugal fan 8 is installed in a space surrounded by the airflow guide plate 6 and the body panel 4. Furthermore, there is provided a drain pan 5, which is molded of a foam material and capable of heat insulation, for temporarily storing condensed water produced in the heat exchanger 3 at the time when the heat exchanger 3 is cooled to perform a cooling operation.
FIG. 8 shows positional relationship of the centrifugal fan with respect to the fan motor 7 at the time when they are mounted in the air conditioner. FIG. 8 is shown upside down with respect to FIG. 7. As shown in FIGS. 7 and 8, the centrifugal fan 8 includes: a main plate 12 having a flat part provided on the outer peripheral side thereof, and a convex-shaped boss part that is provided at the central part thereof, as a fixed part to the rotation shaft of the motor; a plurality of blades 13 installed in an upright position on the main plate 12 in substantially parallel to a rotation axis O; and a ring-shaped side plate 11 having airflow guide wall provided so as to surround the boss part with a predetermined distance therebetween. As shown in FIG. 9, the blades 13 each have a two-dimensional wing shape in which a warped line 13s indicating a blade wall thickness center line is mutually equal in the rotational axis direction. As a result of the rotation of the blades 13, the centrifugal fan sends air from a suction port formed by the boss-side wall surface of the main plate 12 and the end part of the side plate 11 opposite to the boss-side wall surface, toward a blowoff port formed by the outer peripheral side flat part of the main plate 12 and a side plate end part opposite to the outer peripheral side flat part. Hereinafter, a blade edge part located on the downstream side of a blowing direction is referred to as a blade rear edge part.
Here, the side plate outer diameter φDs, the main plate outer diameter φDm, and the blade rear edge part main-plate side outer diameter φDb2m of the centrifugal fan 8 have the following relationship among them:
side plate outer diameter φDs<main plate outer diameter φDm=blade rear edge part main-plate side outer diameter φDb2s. 
Furthermore, the relationship: the main plate outer diameter φDm<fan suction port diameter φDs1 is satisfied, and the outer diameter φDb2 of the blade 3 and the inner diameter φDb1 thereof are configured to become larger from the main plate 12 side toward the side plate 11 side, in the rotation axis direction.
Moreover, the blade rear-edge part 13b is positioned on the inside of the fan from a blade outlet representative line A, which is a straight line connecting the connection point between the blade rear-edge part and the main plate 12, i.e., a blade rear-edge part main-plate side connection point 13bm, and the connection point between the blade rear-edge part and the side plate, i.e., a blade rear-edge part side-plate side junction 13bs, and the blade rear-edge part 13b has a shape such that the distance from a rotation axis O becomes larger from the main plate toward the side plate.
As show in FIG. 9, the blade shape is configured to be a concave curved shape that at least obliquely extends outside an impeller with respect to a blade outlet tilt reference line A1 that is a straight line passing through the blade rear-edge part main-plate side junction 13bm in parallel to the rotation axis O.
Regarding diameters on planes perpendicular to the rotation axis, at the blade rear-edge part main-plate side connection point 13bm, and a blade front-edge part side-plate side connection point 13as, with the rotation axis as their center, let the blade rear-edge part main-plate side diameter be φDb2m, and let the blade leading-edge part side-plate side diameter be φDas1. Then, the relationship: φDb2m<φDas1 holds, resulting in a blade shape in which the diameter become gradually larger from the main plate 12 toward the side plate 11. Also, when a fan suction port diameter, which is a diameter of the side plate front end part 11d with the rotation axis as its center, is denoted by φDs1, the relationship: φDas1<φDs1 holds.
On a surface of the blade, a blade dividing line B is provided that shows a diameter becoming gradually larger from the main plate 12 through the blade rear-edge-part main plate side connection point 13bm and the blade front-edge-side plate side junction 13as toward the side plate 11 in the rotation axis direction, at least within a range meeting the condition: the blade rear-edge part main-plate side diameter φDb2m<the blade front-edge part side-plate side diameter φDas1.
As illustrated in FIG. 9, in the section taken along a line a-a, there is not so large a step 13c between the outer peripheral blade part 13d and the inner peripheral side blade part 13e, while in the section taken along a line b-b shown in FIG. 10, the step 13c between the outer peripheral blade part 13d and the inner peripheral side blade part 13e is larger than that in the case in FIG. 9.
As shown in FIG. 11, the wall-thickness t1 of the outer peripheral blade part 13d on the outer peripheral side from the blade dividing line B becomes gradually larger from the main plate 12 toward the side plate 11, that is, from the section taken along the line c-c toward the section taken along the line a-a. Conversely, the wall-thickness t2 of the inner peripheral side blade part 13e on the inner peripheral side from the blade dividing line B becomes gradually smaller from the main plate 12 toward the side plate 11. The blade shape is configured so that, in the rotation axis direction, at least under the following condition: the wall-thickness t1 of the outer peripheral blade part 13d<the wall-thickness t2 of the inner peripheral side blade part 13e, the height H of the step 13c made by the wall-thickness difference between the inner peripheral side blade part 13e and the outer peripheral blade part 13d on the blade dividing line B becomes gradually larger from the side plate 11 toward the main plate 12.
Furthermore, as described above, the blade shape is configured so that the step 13c existing along the blade dividing line B becomes larger in the distance from the rotation axis O, from the section taken along the c-c line toward the section taken along the a-a line.
In the side plate 11, a side plate suction part 11a having a straight pipe shape and the airflow guide wall 11b for guiding suction flow to the blade 13 at its connection part with the blade 13, are connected, and this connection part 11c has a plane perpendicular to the rotation axis.
In such an air conditioner, upon turning-on the fan motor 7, the centrifugal fan 8 is rotationally driven, so that air in the room 9 is sucked from the ceiling suction port 10 to the space behind the ceiling 9b and passes through the body side-plate side suction port 1a and the body top plate-side suction port 1d; dust, smell and the like have been removed from the room 9 and the space 9b behind the ceiling by the dust removal filter 2, to thereby make air cleaning; and then, the air is subjected to cooling, heating, or dehumidification by the heat exchanger 3, and sucked into the centrifugal fan 8. Thereafter, the flow blown off from the centrifugal fan 8 is subjected to forced air-direction control to move the flow toward obliquely downward direction by the airflow guide plate 6, and the air is blown off from the blowoff port 4a of the body panel 4 provided at a lower part of the body 1, whereby the room 9 is air-conditioned.
The bell mouth 6a of the airflow guide plate 6 and the body top plate 1c are provide so as to be spaced apart by a predetermined distance (E) from each other. If this distance is too small, the flow accelerates between the bell mouth 6a and the body top plate 1c, and drift resistance increases, so that it is necessary to increase the fan revolution number in order to blow a required amount of air. As a consequence, the relative speed with respect to the blades increases, resulting in increased noises. Hence, there exists an applicable range for the distance E between the bell mouth 6a and the body top plate 1c. FIG. 14 is a graph showing the relationship between the ratio (E/H) of the distance E from the bell mouth 6a to the top plate 1c with respect to the body height H, and the noise value under the same air mount condition. As shown in FIG. 14, if the E/H is smaller than 0.3, the effect of the draft resistance increase is large and noises sharply increase. On the other hand, if the E/H is larger than 0.7 and the body height is the same, the centrifugal fan becomes low-profile and an increase in a total pressure decreases, so that the fan revolution number increases, resulting in increased noises. In a case of a different body height, the body height becomes large, leading to a reduction in workability. Therefore, the value of E/H=0.3 to 0.7 allows low noise and size-reduction without reducing installation place.
The air conditioner 1 of the present invention can have the body suction port 1d in the body top plate 1c, in addition to the body suction port 1a in the body side-wall 1b on the upstream side of the heat exchanger 3, and can have the filter 2 so as to completely cover the top plate side suction port 1d, and side-plate side suction port 1a. By such arrangements, the suction port area and the dust removal filter area can be increased, thereby allowing a reduction in draft resistance and noises. Further, a time interval between filter cleaning operations can be elongated, and hence the number of cleaning operations can be reduced, whereby an air conditioner with low noise and maintenance-saving property can be achieved.
FIG. 23 is a longitudinal sectional view of a mixed-flow turbo fan in the Patent Document 1. In FIG. 23, at a position apart from an air conditioner body 200 in a ceiling 208, there is provided a ceiling surface suction port 201 for sucking indoor air in a room 221 into a space 210 behind a ceiling, a body suction port 202a is provided in a body side-wall 202, a filter 203 is provided to the body suction port 202a, and a heat exchanger 204 is arranged behind the body suction port 202a so as be opposed to the body suction port 202a. A blower 206 is provided in a space surrounded by an airflow guide plate 205 and a ceiling panel 207. In the ceiling panel 207 mounted under the body 200, a ceiling panel blowoff port 207a alone is provided.
The conventional air conditioner is configured in this way. Since the direction of blowoff air from the centrifugal fan is a horizontal direction perpendicular to an axis, when a centrifugal fan is installed within the air conditioner body, blowoff flow on the side-plate side and that on the main plate side interfere with each other to thereby enhance a draft resistance and increase noises. As a result, the fan has to be installed to protrude downward from the air conditioner body. It is required, therefore, that the ceiling panel is disposed in a state of protruding from the ceiling surface, which makes the size-reduction of the apparatus difficult, and gives feeling of oppression to people in the room provided with the air conditioner.
However, in the centrifugal fan of this embodiment, a fan blowoff flow is blown off in an oblique direction. In the case where the fan blowoff flow is blown off in the radial direction of the fan as in conventional centrifugal fans, a ceiling panel blowoff port has a horizontal blow configuration, and therefore, below the ceiling panel, the air-conditioned air cannot be blown. In contrast, in the present invention, high comfortability can be obtained everywhere. Also, air is blown off from the ceiling panel in an oblique direction by the airflow guide plate, thereby suppressing the increase in blowoff draft resistance.
Furthermore, since there is no need to arrange the blowoff port of the fan to protrude downward from the body as in the case of the conventional centrifugal fans, the main plate 12, which is the bottom surface of the centrifugal fan 8, and the end of the blowoff port 6b of the airflow guide plate 6 can be disposed at higher places than the ceiling. This facilities size reduction, and does not give feeling of oppression to people in the room provided with the air conditioner.
When air is blown off from the inner peripheral side of the blade 13 toward the outer peripheral side thereof at the step 13c formed by the wall-thickness difference between the inner peripheral side blade part 13e and the outer peripheral side blade part 13d, vortexes G1 are generated and a negative pressure occurs, as shown in FIG. 12 illustrating a flow in the vicinity of the blade level difference 13c shown in FIG. 9. As a result, the flow having passed on the inner peripheral side blade part 13e flows along the outer peripheral blade part 13d, to thereby allow prevention of occurrence of flow separation, and reduces flow separation which is generated at blade rear edge part 4d without the step, to thereby suppress disturbance, leading to a reduction in noises.
FIGS. 13A and 13B are diagrams showing each stage in molding processing. The centrifugal fan of the first embodiment are molded through the following stages: (a) a mold moving stage, (b) a resin injection stage, and (c) a resin cooling stage, as shown in FIG. 13A; and (d) a mold release stage, and (e) a molded component taking-out stage as shown in FIG. 13B. (a) In the mold moving stage, toward a mold 14a, another mold 14b moves and comes into close contact with the mold 14a. To the mold 14a, an injection nozzle 32 for injecting a thermoplastic resin such as ABS, AS, PP, or PS is fixed. (b) In the resin injection stage, the above-described resin is injected from the injection nozzle 32 into a gap formed between the molds 14a and 14b being in a close contact with each other. The resin flows in from the main plate 12 to the boss 12a, and from the main plate 12 through the blade 13 to the side plate 11. Then, (c) in the resin cooling stage, the mold is cooled and the centrifugal fan 1 is formed. Thereafter, (d) in the mold release stage, the mold 14b leaves the mold 14a. At this time, at closely contacting part between the molds 14a and 14b, positioned on the blade of the air conditioner body 1, the blade dividing line B, that is, the step 13c is formed. (e) In the molded component taking-out stage, the air conditioner body 1 as a molded component is taken out from the mold 14a, thus completing the molding.
As described above, by forming the step 13c, during molding, the mold 14b can move in the side plate (11) direction of the rotation axis, on the inner peripheral side from the level difference 13c, and also, on the outer peripheral side, by moving the mold 14a to the main plate (12) side direction of the rotation axis the work can be released, as shown in FIGS. 13A and 13B (mold outline diagrams). This eliminates the need for a slide mold that moves in the direction perpendicular to the rotational axis. As a result, the blade 13, the main plate 12, and the side plate 11 can be integrally molded into one unit, and the molding method becomes simple, so that a molding failure is less prone to be caused, leading to high reliability. Also, by rearrangement or the like, the amount of scrap materials can be suppressed, which is friendly to the environment.
Furthermore, as shown in FIG. 8, since the side plate recess part 11c has a plane perpendicular to the rotational axis, the joint surface between an upper and lower molds does not assume a sharply acute angular shape, and therefore, even if molding is successively performed, the mold is less prone to cause chipped edges of the mold, and hence, it is less prone to a breakdown, so that the number of additional productions of molds can be reduced, thereby allowing resource saving.
Moreover, at this time, since the vortexes G2 arise in the side-plate recess part and a negative pressure occurs, the flow having flowed-in from the side plate suction part 11a can flow along the airflow guide wall 11b preventing flow separation, so that even more noise reduction can be achieved.
When the air conditioner body and ceiling panel are separately transported, in the case where the conventional centrifugal fan is installed to protrude from the air conditioner body, there is possibility that the fan may suffer breakdown under shocks applied thereto at the time when the body is stacked up. Therefore, robust packing materials for covering the fan's portion protruding from the body are required. In contrast, in the present invention, since the centrifugal fan is accommodated within the body, simple packing is only needed, thereby allowing reduction in packing materials. Also, a fan breakdown can be less likely to occur, and transportation quality can also be enhanced.
Moreover, since there is no need for increase in installation height in a space behind the ceiling, and the ceiling panel can be substantially flush with the room side surface of the ceiling, that is, the fan does not protrude toward the room side unlike the conventional case, so that people in the room do not suffer feeling of oppression.
The airflow guide plate is integrally formed of the airflow guide part being formed into a truncated cone shape in a gradually enlarging manner so as to isolate the fan suction airflow path from the blowoff airflow path and to guide a fan blowoff flow to the outside of the machine, and of the bell mouth. Therefore, the fan suction flow is rectified, as well as the increase in draft resistance of the fan blowoff flow is suppressed, thereby preventing increase in noises. In addition, since the airflow guide wall and the bell mouth are integrated in one unit, work efficiency is high during assembly or disassembly for recycling, because of a low number of components.
As a consequence, a reduction in packing materials can be achieved by virtue of breakdown prevention during transportation of the centrifugal fan. This enhances transportation quality, and facilitates assembly/disassembly as well as improves recycling workability. Furthermore, since the blades, the main plate, and the side plate can be molded into one unit, the molding method is simplified, and molding failure is less prone to occur, thereby enhancing reliability. As a result, the amount of scrap materials due to rearrangement or the like can be suppressed, which is friendly to the environment. Moreover, residents do not suffer stresses due to feelings of oppression, and there are no temperature variations, leading to high comfortability. Thus, an air conditioner having low noise and high maintenance-saving properties can be obtained.
Second Embodiment
Hereinafter, an air conditioner according to a second embodiment of the present invention will be described with reference to FIGS. 15 to 17.
FIG. 15 is a perspective view of an air conditioner according to the second embodiment of the present invention, at the time when the air conditioner body and ceiling panel are installed; FIG. 16 is a longitudinal sectional view of the air conditioner taken along section indicating lines J1 to J3 in FIG. 15; and FIG. 17 is a horizontal sectional view at the height positions of L1-L2 and L3-L4 in FIG. 16, wherein the section at each of these two height positions is shown in a half in the illustration. In the second embodiment, regarding main constitution and corresponding symbols, the same ones as those in the first embodiment are used.
As shown in FIG. 15, the air conditioner body 1 has a rectangular parallelepiped and vertically long shape. Under the body 1, there is provided a body panel 4 having a rectangular shape. As shown in FIGS. 16 and 17, a body side-plate side suction port 1a is provided to a body side-wall 1b, and a body top plate-side suction port 1d is arranged along a body side-wall 1b of a body top plate 1c. A dust removal filter 2 is arranged so as to completely cover the body side-plate side suction port 1a and the body top plate-side suction port 1d, and a heat exchanger 3 is installed in an upright position on the downstream thereof along the side-wall 1b. 
There is provided a fan blowoff airflow guide plate 6 that is integrally formed combination of an airflow guide part 6c and a bell mouth 6a, the airflow guide part 6c being formed into a truncated cone shape in a gradually enlarging manner so as to isolate a fan suction air path Ma of a centrifugal fan 8 from a blowoff air path Mb thereof. The tilt angle γ of the airflow guide part 6c of the fan blowoff airflow plate 6 is configured so that the angle γ1 in the longer direction of the body 1 is larger than the angle γ2 in the shorter direction thereof, and an airflow plate blowoff port 6b is formed into an ellipse shape, as shown in FIG. 16.
By forming the fan blowoff airflow plate 6 in this manner, even when the air conditioner body is formed into a vertically long shape because of limitations of an installation space such as an elongate room, a blowoff flow of the centrifugal fan reaches the body longitudinal direction, and is uniformly blown off from the ceiling panel blowoff port, so that unevenness temperature in the room can be suppressed, thereby allowing an enhancement of comfortability.
Third Embodiment
Hereinafter, an air conditioner according to a third embodiment of the present invention will be described with reference to FIGS. 18 to 20.
FIG. 18 is a perspective view of an air conditioner body and a ceiling panel at the time of installation, according to a third embodiment of the present invention; FIG. 19 is a longitudinal sectional view corresponding to FIG. 18; and FIG. 20 is a horizontal sectional view taken along section indicating lines k1 to k4 in FIG. 19. In the third embodiment, regarding main constitution and corresponding symbols, the same ones as those in the first embodiment are used. In FIG. 18, the body panel 4 is configured so that its blowoff port 4a is opened in a substantially square shape and that the centrifugal fan 8 becomes less visible from directly below the body panel 4 due to the central panel 4b in the central part.
As shown in FIG. 19, an outer frame of the body panel 4 is fixed to the air conditioner body 1 to thereby constitute a bottom surface of the body, and a central panel 4 in the central part of the body panel 4 is configured so as to be capable of opening and closing or hinges and being removed. Inside the ceiling panel 4, there is provided an electrical component box for accommodating electrical components such as an electrical substrate 15a for the power supply to a fan motor 7, revolution number control, and the exchange of control signals with an outdoor machine (not shown).
Furthermore, the airflow guide plate 6 that is integrally formed of the airflow guide part 6c, which is formed into a truncated cone shape in a gradually enlarging manner so as to isolated a fan suction air path Ma from a blowoff air path Mb and to guide a fan blowoff flow to the outside of the machine, and the bell mouth 6a, and the centrifugal fan are small relatively to a ceiling panel central opening 4c at the time when the central panel 4b is removed. Therefore, the airflow guide plate 6 and the centrifugal fan 8 can be removed from the body panel central opening 4c. 
A side wall 5a of a drain pan 5 has a tilt shape along the tilt shape airflow guide part 6c of the fan blowoff airflow guide plate 6. Here, in the air conditioner 1 of the third embodiment, there are provided a plurality of columns of the heat exchangers 3. The upper end parts of the heat exchangers 3 are flush with each other, and that the lower end parts thereof are arranged in a staircase pattern along the tilted side wall of the drain pan. As a result, even though the column direction width increases by forming the plurality of columns of heat exchangers, the body size does not increase, and can be still kept compact.
By forming the ceiling-embedded air conditionerin this manner, since the blowoff port of the ceiling panel is opened in a substantially square shape, the centrifugal fan is invisible from people directly below the ceiling panel 4, leading to a favorable design. Also, since air is blown off all around, unevenness of temperature in the room are suppressed to thereby enhance comfortability. Even if the opening shape is changed to a substantially circle shape, similar effects can be obtained.
Since the outer frame of the ceiling panel is fixed to the body to thereby constitute a bottom surface of the body, and the central part of the ceiling panel is capable of being removed, even at the time when the centrifugal fan is cleaned or the fan motor goes out of order, work can be performed without removing the airflow guide plate, thus improving work efficiency of cleaning, repair, or the like.
Moreover, since the central part of the ceiling panel is made an electrical component box for accommodating electrical components such as a substrate and the like, even if wiring or a substrate of electrical components goes out of order, work can be performed without removing components within the body, thus improving work efficiency of repair.
Also, since there is no electrical component in air paths, neither reduction in air paths on the suction side and the blowoff side, nor increase in draft resistance occur, thereby allowing low noise to be kept.
Furthermore, the airflow guide plate that is integrally formed of the air guide part which is formed into a truncated cone shape in a gradually enlarging manner so as to isolated the fan suction air path from the fan blowoff air path and to guide a fan blowoff flow to the outside of the machine and the bell mouth, and the centrifugal fan are small relatively to the ceiling panel central opening at the time when the ceiling panel central part is removed, and the airflow guide plate and the centrifugal fan can be removed from the ceiling panel opening part. Therefore, when attempting to clean the inside of the body, there is no need for removal of the ceiling panel, thereby facilitating cleaning.
As a result, a ceiling-embedded air conditioner with low noise and high maintenance saving properties can be obtained.
As shown in FIG. 21, when all of the heat exchangers 3, or the heat exchangers 3 on the upstream side as shown in FIG. 20 is changed to an air cleaning filter 2a, small and dust can be removed, thereby allowing the room and the space behind the ceiling to be always kept in sanitary conditions.
As shown in FIG. 22, when all of the heat exchangers 3, or the heat exchanger 3 on the upstream side as shown in FIG. 20 is changed to an humidifying filter 2b, a humidification tank 16 for temporarily storing water of water piping connected from outside of the body 1 is arranged at a corner portion where a humidifying filter 2b of the body 1 is not provided, the temperature in the room can always be kept constant.

## Claims

1. An air conditioner comprising:
a body panel that is provided in a ceiling of a room air-conditioned by the air conditioner and that has a blowoff port for air from the inside of an air conditioner body;
a side wall installed in an upright position, along the outer periphery of the body panel;
an air conditioner top plate provided so as to cover a surface of the side wall opposed to the body panel;
a body suction port formed in the side wall of the air conditioner body;
a heat exchanger provided in the vicinity of the body suction port, inside the side wall;
a fan motor fixed to the air conditioner top plate;
a centrifugal fan having a convex-shaped boss part fixed to a rotation shaft of the fan motor, the centrifugal fan sucking the air sucked via the body suction port and the heat exchanger as a result of the rotation of the rotation shaft, and blowing off the air to the room; and
a airflow guide plate that isolates an air flow on the suction side of the centrifugal fan from an air flow on the blowoff side thereof, and that guides a blowoff flow of the centrifugal fan to the blowoff port of the body panel,
wherein the centrifugal fan comprises:
a main plate having a flat part provided on the outer peripheral side thereof, and the boss part provided at a central part thereof;
a side plate having an airflow guide wall provided so as to surround the boss part with a predetermined distance therebetween; and
a plurality of blades provided between the main plate and the side plate so as to be substantially orthogonal to a plane perpendicular to the rotation axis; and
wherein, with the rotation of the plurality of blades, the centrifugal fan blows air from a suction port formed of a boss-side wall surface and a side plate end part opposite to the boss-side wall surface, toward a blowoff port formed of an outer peripheral side flat part of the main plate and an end part of the side plate opposite to the outer peripheral side flat part;
wherein, when an edge part of the blade positioned on the down stream side of a blowing direction is taken as a blade rear edge part, the centrifugal fan has the following relationship:
outer diameter of the side plate > outer diameter of the blade rear-edge part on side-plate side > diameter of the blade rear-edge part on main plate side ≧ outer diameter of the main plate;
wherein the blade rear-edge part is positioned inside from a straight line connecting the connection point between the blade rear-edge part and the main plate, to the connection point between the blade rear-edge part and the side plate, as viewed from the rotation axis; and
wherein the blade rear-edge part has a shape such that the distance from the rotational axis becomes larger from the main plate toward the side plate.

2. The air conditioner of claim 1,
wherein the centrifugal fan has a straight-pipe shape side-plate suction port provided on a side end part of the suction port in the airflow guide wall of the side plate;
the airflow guide plate has a bell mouth part provided so as to cover the side plate suction port from the inner peripheral side to the outer peripheral side thereof, and has an airflow guide part formed into a truncated cone shape along the airflow guide wall of the side plate.

3. The air conditioner according to claim 2, wherein the ratio (E/H) of the distance E of closest approach between the bell mouth part of the airflow guide plate and the body top plate to the body height H is set to 0.3 to 0.7.

4. The air conditioner of claim 1,
wherein a body suction port is further formed in the body top plate on the upstream side of the heat exchanger; and
a filter is provided so as to cover the suction ports formed in the top plate and the side-plate.

5. The air conditioner of claim 1,
wherein the wall thickness of an outer peripheral side blade part located on the outer peripheral side from a blade dividing line connecting the connection point between the rear-edge part of the blade and the main plate, and the connection point between the front-edge part thereof, and the side plate, is smaller than that of an inner peripheral side blade part; and
a step is formed between the outer peripheral side blade part and the inner peripheral side blade part.

6. The air conditioner of claim 5,
wherein the wall thickness of the outer peripheral side blade part located on the outer peripheral side from the blade dividing line becomes larger from the main plate toward the side plate, and conversely, the wall thickness of the inner peripheral side blade part located on the inner peripheral side from the blade dividing line becomes smaller from the main plate toward the side plate; and
the blade is configured so that the step formed by the wall-thickness difference between the inner peripheral side blade part and the outer peripheral side blade part, becomes larger from the side-plate side toward the main plate side.

7. The air conditioner of claim 6,
wherein the air conditioner has the following relationship: the diameter of the blade rear-edge part on main plate side < the diameter of the blade front-edge part on side-plate side; and
the blade dividing line is configured so that the distance between a point on the blade dividing line and the rotational axis is positioned at least between the radius of the blade rear-edge part on main plate side and the radius of the blade front-edge part on side-plate side, and that the distance to the rotation axis becomes larger from the main plate toward the side plate.

8. The air conditioner of claim 1,
wherein the air conditioner body has an elongated shape in a horizontal section thereof;
the heat exchanger has a rectangular section substantially along the side plate;
the fan blowoff airflow guide plate is integrally formed of the airflow guide part and a bell mouth, the air guide part being formed into a truncated cone shape in a gradually enlarging manner so as to isolated the suction air path of the centrifugal fan from the blowoff air path thereof and to guide the fan blowoff flow to the outside of the machine; and
the airflow guide wall of the fan blowoff airflow guide plate is configured so that the tilt angle thereof is larger in the longer direction of the heat exchanger than in the shorter direction thereof, and a airflow guide plate blowoff port is formed into an ellipse shape.

9. The air conditioner of claim 1, wherein the blowoff port in the ceiling panel has an opening with a substantially square shape or ring shape.

10. The air conditioner of claim 9,
wherein an outer frame of the ceiling panel is fixed to the body to thereby constitute a bottom surface of the body; and
a central part of the ceiling panel is configured to be removable.

11. The air conditioner of claim 9, wherein the central part of the ceiling panel is made an electrical component box for accommodating electrical components such as a substrate and the like.

12. The air conditioner of claim 1, wherein the fan blowoff airflow guide plate and the centrifugal fan are small relative to the ceiling panel opening part at the time when the ceiling panel central part is removed.

13. The air conditioner of claim 1,
wherein the heat exchanger is constituted in a plurality of columns;
the air conditioner body further has a drain pan with a tilt shaped side wall along the airflow guide wall of the fan blowoff airflow guide plate; and
the plurality of columns of the heat exchanger are installed in upright positions in a way such that the upper end parts of the plurality of columns of the heat exchanger are flush with each other, and that the lower end parts thereof are arranged in a staircase pattern along the tilted side wall of the drain pan.

14. The air conditioner of claim 13, wherein all or some of the plurality of columns of the heat exchanger are air cleaning filters.

15. The air conditioner of claim 13, wherein all or some of the plurality of columns of the heat exchanger are air humidifying filters.