INDOOR UNIT OF FLOOR-TYPE AIR CONDITIONER BACKGROUND OF THE INVENTION [0001] 5 The present invention relates to an indoor unit of a floor-type air conditioner having a centrifugal fan generating an air flow in centrifugal direction. [0002] A known indoor unit of an air conditioner is 10 arranged such that, by using a centrifugal fan housed in a casing, air sucked through an inlet port on the front of the casing is arranged to. be an air flow in centrifugal direction, and the air flow is blown out from an inlet port provided around the outlet port (see e.g. Patent 15 Document 1) . In this indoor unit of Patent Document 1, the air flow blown out from the centrifugal fan in centrifugal direction collides a guide wall (fan casing) which is radially outside the centrifugal fan, so that the air flow is guided to the outlet port. 20 [Patent Document] [0003] [Patent Document 1] Japanese Unexamined Patent Publication No. 2007-183013 [0004] 25 The indoor unit of Patent Document 1, however, is 1 disadvantageous in that noise is generated because the air flow blown out from the centrifugal fan in centrifugal direction collides the guide wall (fan casing). 5 SUMMARY OF THE INVENTION [0005] The present invention was done to solve this problem and hence an object of the present invention is to provide an indoor unit of a floor-type air conditioner which is 10 capable of restraining noise caused by the collision of air blown out from a centrifugal fan onto a casing or the like. [0006] An indoor unit of a floor-type air conditioner 15 according to the first aspect of the invention includes: a centrifugal fan which generates an air flow in centrifugal direction; and a casing which stores the centrifugal fan and has an inlet port sucking air from outside to supply the air to the centrifugal fan and an outlet port which 20 blows out an air flow generated by the centrifugal fan to the outside, wherein, the centrifugal fan includes a main blade, a sub blade on the outlet port side of the main blade, and a plurality of blades provided between the main blade and the sub blade, the main blade has a first 25 extension portion which extends from an outer periphery of 2 the main blade toward the outside of outer peripheries of the blades and is inclined toward the outlet port, and the sub blade includes a second extension portion which extends from an outer periphery of the sub blade toward 5 the outside of outer peripheries of the blades and is inclined toward the outlet port. [0007] This indoor unit of the floor-type air conditioner arranges, by means of the first extension portion and the 10 second extension portion, an air flow blown out in centrifugal direction from the space between the main blade and the sub blade to be an air flow toward the outlet ports. In other words, the indoor unit is able to form a smooth air flow which moves from the centrifugal 15 fan to the outlet ports in the casing without colliding the casing or the like. As a result, it is possible to restrain the noise caused by the collision of an air flow blown out from the centrifugal fan onto the casing or the like. 20 [00081 According to the second aspect of the invention, the indoor unit of the floor-type air conditioner according to the first aspect of the invention is arranged so that the first extension portion and the second extension portion 25 are both linearly inclined, and an angle of inclination of 3 the first extension portion is smaller than an angle of inclination of the second extension portion. [0009] According to this indoor unit of the floor-type air 5 conditioner, since the angle of inclination of the first extension portion on the main blade side where the air flow blown out from the centrifugal fan is fast is arranged to be smaller than that of the second extension portion, the fast air flow on the main blade side is 10 directed toward the outlet ports without being sharply diverted. [0010] According to the third aspect of the invention, the indoor unit of the floor-type air conditioner according to 15 the first aspect of the invention is arranged so that the first extension portion is linearly inclined whereas the second extension portion is curved and inclined. [00111 In addition to the above, the indoor unit of the 20 floor-type air conditioner is arranged so that the second extension portion on the sub blade side, where the air flow is slow, is curved. This facilitates airflow to the outlet ports. [0012] 25 According to the fourth aspect of the invention, the 4 indoor unit of the floor-type air conditioner according to any one of the first to third aspects of the invention is arranged so that the external diameter of the first extension portion is identical with the external diameter 5 of the second extension portion. (0013] According to this indoor unit of the floor-type air conditioner, the first extension portion and the second extension portion are efficiently extended in the casing 10 which defines the maximum size of the external diameter of the centrifugal fan. [0014] According to the fifth aspect of the invention, the indoor unit of the floor-type air conditioner according to 15 any one of the first to fourth aspects of the invention is arranged so that the first extension portion is formed along the entire outer periphery of the main blade, and the second extension portion is formed along the entire outer periphery of the sub blade. 20 [0015] This indoor unit of the floor-type air conditioner allows the air flow blown out in centrifugal direction to be equally directed to the outlet ports from the entire outer peripheries of the main blade and the sub blade. 25 [0016] 5 As described above, the following effects are obtained from the present invention. [0017] According to the first aspect of the invention, by 5 means of the first extension portion and the second extension portion, an air flow blown out in centrifugal direction from the space between the main blade and the sub blade are arranged to be an air flow toward the outlet ports. Therefore, the indoor unit is able to form a 10 smooth air flow which moves from the centrifugal fan to the outlet ports in the casing without colliding the casing or the like. As a result, it is possible to restrain the noise caused by the collision of an air flow blown out from the centrifugal fan onto the casing or the 15 like. [0018] According to the second aspect of the invention, c since the angle of inclination of the first extension portion on the main blade side where the air flow blown 20 out from the centrifugal fan is fast is arranged to be smaller than that of the second extension portion, the fast air flow on the main blade side is directed toward the outlet ports without being sharply diverted. [0019] 25 According to the third aspect of the invention, the 6 second extension portion on the sub blade side, where the air flow is slow, is curved. This facilitates airflow to the outlet ports. [0020] 5 According to the fourth aspect of the invention, the first extension portion and the second extension portion are efficiently extended in the casing which defines the maximum size of the external diameter of the centrifugal fan. 10 [0021] According to the fifth aspect of the invention, the first extension portion is formed along the entire outer periphery of the main blade, and the second extension portion is formed along the entire outer periphery of the 15 sub blade. BRIEF DESCRIPTION OF THE DRAWINGS [0022] Fig. 1 is a circuit diagram of a refrigerant circuit 20 of an air conditioner according to First Embodiment of the present invention. Fig. 2 is an oblique perspective showing the appearance of the floor-type indoor unit. Fig. 3 is a cross section of the floor-type indoor 25 unit shown in Fig. 2. 7 Fig. 4 is an elevation view showing the internal structure of the floor-type indoor unit shown in Fig. 2. Fig. 5 is a schematic cross section of the fan unit and the bottom frame. 5 Fig. 6 is an oblique perspective of the turbofan. Fig. 7 is an elevation of the turbofan. Fig. 8 is a cross section taken along the A-A line in Fig. 7. Fig. 9 is an oblique perspective when the shutter 10 unit is viewed from the back side. Fig. 10 is an oblique perspective when the shutter unit is viewed from the back side. Fig. 11 is a cross section of the shutter unit when the shutter is open. 15 Fig. 12 is a cross section of the shutter unit when the shutter is closed. Fig. 13 is a graph showing the relationship between an angle of inclination of the extension portion of the main blade of First Embodiment and noise. 20 Fig. 14 is a graph showing the relationship between an angle of inclination of the extension portion of the main blade of First Embodiment and an input to the fan motor. Fig. 15 is a schematic cross section of a turbofan 25 according to Second Embodiment of the present invention. 8 Fig. 16 is a schematic cross section of a turbofan according to Third Embodiment of the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS 5 [0023] The following will describe an embodiment of an air conditioner having a floor-type indoor unit according to the present invention, with reference to figures. [0024] 10 (First Embodiment) Fig. 1 is a circuit diagram of a refrigerant circuit of an air conditioner according to First Embodiment of the present invention. Fig. 2 is an oblique perspective showing the appearance of the floor-type indoor unit. Fig. 15 3 is a cross section of the floor-type indoor unit shown in Fig. 2. Fig. 4 is an elevation view showing the internal structure of the floor-type indoor unit shown in Fig. 2. Now, an air conditioner according to an embodiment of the present invention will be described with 20 reference to Fig. 1 to Fig. 4. [0025] <Air Conditioner> An air conditioner 100 according to an embodiment of the present invention is an apparatus for supplying 25 conditioned air into a room, and includes, as shown in Fig. 9 1, a floor-type indoor unit (hereinafter, indoor unit) 1 disposed in the room, an outdoor unit 2 disposed outside the room, and a connection pipe 3 connecting the indoor unit 1 with the outdoor unit 2. The components and valves 5 housed in the indoor unit 1 and the outdoor unit 2 and the connection pipe 3 are connected with one another and constitute a refrigerant circuit. The refrigerant circuit is chiefly made up of an indoor heat exchanger 10, an outdoor heat exchanger 20, an accumulator 21, a compressor 10 22, a four-pass switching valve 23, and an electric expansion valve 24. [0026] In the air conditioner 100 arranged as above, the four-pass switching valve 23 is switched to the position 15 indicated by the solid line, when heating. As a result, a hot high-pressure refrigerant discharged from the compressor 22 flows into the indoor heat exchanger 10 via the four-pass switching valve 23. The refrigerant condensed in the indoor heat exchanger (condenser) 10 is 20 depressurized by the electric expansion valve 24 and then flows into the outdoor heat exchanger 20. Thereafter, the refrigerant evaporated in the outdoor heat exchanger (evaporator) 20 returns to the sucking side of the compressor 22 via the four-pass switching valve 23 and the 25 accumulator 21. As such, the air around the indoor heat 10 exchanger 10 is heated and hot air is supplied into the room. [0027] On the other hand, when cooling, the four-pass 5 switching valve 23 is switched to the position indicated by a dotted line. Upon switching, the hot high-pressure refrigerant discharged from the compressor 22 flows into the outdoor heat exchanger 20 via the four-pass switching valve 23. The refrigerant condensed in the outdoor heat 10 exchanger (condenser) 20 is depressurized by the electric expansion valve 24, and then flows into the indoor heat exchanger 10. Thereafter, the refrigerant evaporated in the indoor heat exchanger (evaporator) 10 returns to the sucking side of the compressor 22 via the four-pass 15 switching valve 23 and the accumulator 21. As such, the air around the indoor heat exchanger 10 is cooled and cool air is supplied to the room. (0028] <Outdoor Unit> 20 The outdoor unit 2 includes the compressor 22, the four-pass switching valve 23 connected to the discharging side of the compressor 22, the accumulator 21 connected to the sucking side of the compressor 22, the outdoor heat exchanger 20 connected to the four-pass switching valve 23, 25 the electric expansion valve 24 connected to the outdoor 11 heat exchanger 20, and an outdoor fan 25 attached to the outdoor heat exchanger 20. The electric expansion valve 24 is connected to a liquid refrigerant pipe 31, and is further connected to one end of the indoor heat exchanger 5 10 via the liquid refrigerant pipe 31. The four-pass switching valve 23 is connected to a gas refrigerant pipe 32, and is further connected to the other end of the indoor heat exchanger 10 via the gas refrigerant pipe 32. The refrigerant pipes 31 and 32 are equivalent to the 10 above-described connection pipe 3. [0029] <Indoor Unit> The indoor unit 1 is, as shown in Fig. 2 and Fig. 3, a floor-type indoor unit and chiefly includes a casing 15 unit 50, an indoor heat exchanger 10 housed in the casing unit 50, a fan unit 60, and a shutter unit 70. [0030] <Casing Unit> The casing unit 50 constituting the contour of the 20 indoor unit 1 includes a front panel 51, a front grill 52, a bottom frame 53, and a back heat-insulating material 54. These components are disposed in the order of, from the front side of the indoor unit 1, the front panel 51, the front grill 52, the bottom frame 53, and the back heat 25 insulating material 54. The space formed inside the 12 casing unit 50 is, as shown in Fig. 4, divided into a fan chamber 50A in which the indoor heat exchanger 10, the fan unit 60 and the like are provided, and a pipe chamber 50B in which electric units or the like are provided. 5 [0031] The front panel 51 is, as shown in Fig. 2 and Fig. 3, attached to cover a filter 55 which is attached to the front grill 52. At the top of this front panel 51 is provided an upper inlet port Sla, whereas at the bottom of 10 the front panel 51 is provided a lower inlet port 51b. Furthermore, on the both sides of the front panel 51 are formed side inlet ports 51c. The upper inlet port 51a and the lower inlet port 51b are long in the width directions (X directions) whereas the side inlet ports 51c are long 15 in the vertical directions (Z directions) . These ports allow the unit to suck indoor air in four directions, i.e. from above, from below, from left, and from right, and the air sucked through the inlet ports 51a, 51b, and 51c are evenly passes through the indoor heat exchanger 10. 20 [0032] The front grill 52is, as shown in Fig. 2 and Fig. 3, provided between the front panel 51 and the indoor heat exchanger 10. At the top of the front grill 52 is provided an upper outlet port 52a, whereas at the bottom 25 of the front grill 52 is provided a lower outlet port 52b. 13 These upper outlet port 52a and the lower outlet port 52b are both long in the width directions (X directions) . At the center of the front grill 52 is formed a substantially rectangular parallelepiped opening 52c. This opening 52c 5 is provided with a filter 55 to catch the dust in the air sucked through the inlet ports Sla, 51b, and 51c of the front panel 51. [0033] The bottom frame 53 is, as shown in Fig. 3, disposed 10 between the later-described fan unit 60 and the back heat insulating material 54. This bottom frame 53 includes a bottom portion 53a forming the bottom of the indoor unit 1 and a standing portion 53b standing on the bottom portion 53a. The bottom portion 53a is provided with a pipe 15 introducing hole 53c to introduce the connection pipe 3 into the pipe chamber 50B (see Fig. 4) . Substantially at the center of the standing portion 53b is provided a fan attaching portion 53d for attaching the fan unit 60 thereto. 20 [0034] The back heat-insulating material 54 is provided on the back side of the bottom frame 53 for heat insulation. [0035] In the casing unit 50 structured as above, as shown 25 in Fig. 3, an upper air duct 50a is formed to connect a 14 later-described turbofan 62 with the upper outlet port 52a. This upper air duct 50a is formed along the inner wall surface of the bottom frame 53. This duct 50a curves and extends forward and upward from the turbofan 62 to the 5 upper outlet port 52a. Above the upper air duct 50a are provided a vertical flap 40 by which the direction of air flow blown out from the upper outlet port 52a is controlled in regard to the horizontal direction and a horizontal flap 41 by which the direction of air flow is 10 controlled in regard to the vertical direction. In the casing unit 50, furthermore, a lower air duct 50b is formed to connect the turbofan 62 with the lower outlet port 52b. The lower air duct 50b curves and extends forward and downward from the turbofan 62 to the lower 15 outlet port 52b. Above this lower air duct 50b is provided a vertical flap 42 by which the direction of air flow blown out from the lower outlet port 52b is controlled in regard to the horizontal direction. On the windward side of the vertical flap 42 is provided a later 20 described shutter 72. [0036] <Indoor Heat Exchanger> The indoor heat exchanger 10 is provided for conducting heat exchange with the indoor air. This indoor 25 heat exchanger 10 is, as shown in Fig. 3, provided between 15 the fan unit 60 and the front grill 52 and conducts heat exchange on the windward side of the fan unit 60. (0037] * <Bell-Mouth> 5 In addition to the above, between the indoor heat exchanger 10 and the fan unit 60 is provided a bell-mouth 11. This bell-mouth 11 guides the air having passed through the indoor heat exchanger 10 to the later described turbofan 62 (opening 64a). 10 [0038] <Fan Unit> Fig. 5 is a schematic cross section of the fan unit and the bottom frame. Fig. 6 is an oblique perspective of the turbofan, Fig. 7 is an elevation of the turbofan, and 15 Fig. 8 is a cross section taken along the A-A line in Fig. 7. Now, the fan unit 60 will be detailed with reference to drawings such as Fig. 5 to Fig. 8. [0039] The fan unit 60 includes a fan motor 61 which is a 20 drive source and provided on the leeward side of the indoor heat exchanger 10 and the turbofan 62 which is a type of centrifugal fan generating an air flow in centrifugal direction. The air flow generated by this fan unit 60 is blown out from the upper outlet port 52a via 25 the above-described upper air duct 50a and from the lower 16 outlet port 52b via the lower air duct 50b. [0040] The fan motor 61 is attached to the fan attaching portion 53d (see Fig. 3) of the standing portion 53b of 5 the bottom frame 53. The motor shaft 61a of this fan motor 61 extends in the front-back directions (Y directions), and rotates about a rotational axis extending in the front-back directions. [0041] 10 As shown in Fig. 3, the turbofan 62 is attached to the motor shaft 61a of the fan motor 61 and rotates in accordance with the rotation of the motor shaft 61a. This turbofan 62 includes, as shown in Fig. 5 to Fig. 8, a main blade 63, a sub blade 64 opposing the main blade 63, and 15 seven blades 65 provided between the main blade 63 and the sub blade 64. [0042] The main blade 63 is substantially disc-shaped in elevation, and a protrusion 63a protruding toward the sub 20 blade 64 is formed at its center. This protrusion 63a is formed to correspond to the fan motor 61, and is attached to the above-described motor shaft 61a. Around the protrusion 63a formed substantially at the center of the main blade 63, a flat portion 63b is formed to extend 25 along the plane orthogonal to the above-described motor 17 shaft 61a. In the present embodiment, as shown in Fig. 5 and Fig. 8, the main blade 63 further has an extension portion 63c which linearly extends from the outer periphery of the main blade 63 toward the outside of the 5 outer peripheries of the seven blades 65. This extension portion 63c is inclined for an angle of theta (see Fig. 5) toward the sub blade 64, with respect to the flat portion 63b. The extension portion 63c is arranged to be close to the sub blade 64 toward its leading end. 10 [0043] The sub blade 64 is spaced apart from the main blade 63 and is on the port 52a side and on the port 52b side of the main blade 63. This sub blade 64 is substantially ring-shaped in elevation and an opening 64a formed at its 15 center functions as an air inlet. In the present embodiment, furthermore, the sub blade 64 has an extension portion 64b which curves and extends from the outer periphery of the sub blade 64 toward the outside of the outer peripheries of the seven blades 65. This extension 20 portion 64b is inclined away from the main blade 63. More specifically, the extension portion 64b is arranged to be close to the outlet ports 52a and 53b toward its leading end. The sub blade 64 is further provided with an extension portion 64c which curves and extends inward from 25 its inner periphery. This extension portion 64c is 18 inclined away from the main blade 63 in the same manner as the extension portion 64b described above. More specifically, the extension portion 64c is arranged to be close to the outlet ports 52a and 52b toward its leading 5 end. [0044] In the present embodiment, as shown in Fig. 6, the extension portion 63c of the above-described main blade 63 is formed along the entirety of the outer periphery, and 10 the extension portion 64b of the sub blade 64 is formed along the entirety of the outer periphery. Furthermore, as shown in Fig. 5, the external diameter R1 of the extension portion 63c is identical with the external diameter R2 of the extension portion 64b. 15 [0045] The seven blades 65 are, as shown in Fig. 7, provided at predetermined intervals and angles along the direction of the rotation of the turbofan 62. [0046] 20 As shown in Fig. 3 and Fig. 5, as the fan motor 61 is activated, the turbofan 62 rotates, the air having passed through the indoor heat exchanger 10 is sucked into the turbofan 62 via the opening 64a, with the result that an air flow in centrifugal direction is generated. This 25 air flow in centrifugal direction is directed toward the 19 outlet ports 52a and 52b of the indoor unit 1 by the extension portion 63c of the main blade 63 and the extension portion 64b of the sub blade 64. In other words, the air flow blown out from the upper part of the turbofan 5 62 progresses along the upper air duct 50a and is then blown out from the casing unit 50 through the upper outlet port 52a. The air flow blown out from the lower part of the turbofan 62 progresses along the lower air duct 50b and is then blown out from the casing unit 50 through the 10 lower outlet port 52b. [0047] <Shutter Unit> Each of Fig. 9 and Fig. 10 is an oblique perspective when the shutter unit is viewed from the back side. Fig. 15 11 is a cross section of the shutter unit when the shutter is open. Fig. 12 is a cross section of the shutter unit when the shutter is closed. Now, the shutter unit 70 will be detailed with reference to drawings such as Fig. 9 to Fig. 12. 20 [0048] The shutter unit 70 is provided around the lower outlet port 52b and determines whether the air flow from the turbofan 62 to the lower outlet port 52b is allowed to be blown to the outside, by opening or closing a port 50c 25 on the lower air duct 50b which connects the turbofan 62 20 with the lower outlet port 52b. This shutter unit 70 is provided with a shutter driving motor 71 which is a drive source, the shutter 72, and a shutter casing 73 which rotatably supports the shutter 72. 5 [0049] The shutter casing 73 includes, as shown in Fig. 4, Fig. 9, and Fig. 10, a shutter supporter 73a to which the shutter driving motor 71 and the shutter 72 are attached and a drain pan 73b provided above the shutter supporter 10 73a. The shutter supporter 73a is a tubular member functioning as a part of the above-described lower air duct 50b as shown in Fig. 9 and Fig. 10, and its longitudinal end is attached to a mounting portion 73c to which the shutter driving motor 71 is mounted. This 15 mounting portion 73c has a through hole 73d (see Fig. 10) through which the motor shaft 71a of the shutter driving motor 71 penetrates. The other longitudinal end of the shutter supporter 73a is attached to a bearing portion 73e which rotatably supports a later-described shaft 72b of 20 the shutter 72. The drain pan 73b is, as shown in Fig. 4, disposed along the lower edge of the indoor heat exchanger 10 and receives water drained from the indoor heat exchanger 10. This drain pan 73b is arranged to be inclined downward toward the pipe chamber 50B. At the 25 bottom of the drain pan 73b on the pipe chamber 50B side, 21 a drain pipe 73f is provided to drain the water in the drain pan to the outside. [0050] The shutter driving motor 71 is a stepper motor and 5 is provided outside the shutter casing 73 so as not to obstruct the air flow in the lower air duct 50b. The motor shaft 71a of this shutter driving motor 71 is, as shown in Fig. 10, attached to the shutter 72 via the through hole 73d penetrating the shutter casing 73. The 10 shutter driving motor 71 rotates the shutter 72 in the direction of the arrow G about a rotational axis extending along the longitudinal directions of the shutter 72. The shutter 72 therefore moves from the open position shown in Fig. 11 to the close position show in Fig. 12 or moves 15 from the close position shown in Fig. 12 to the open position shown in Fig. 11. [0051] The shutter 72 is provided around the lower outlet port 52b. This shutter 72 is able to take a position to 20 close the port 50c on the lower air duct 50b and a position to open the port 50c. The shutter 72 is, as shown in Fig. 9 and Fig. 10, arranged to be long in the width directions (X directions) of the indoor unit 1. At one longitudinal end of the shutter 72 is provided a 25 fitting hole 72a to which the motor shaft 71a of the 22 shutter driving motor 71 is fit, whereas at the other longitudinal end is provided the shaft 72b which is rotatably supported by the bearing portion 73e. [0052] 5 <Features of Floor-Type Indoor Unit of Present Embodiment> The floor-type indoor unit 1 of the present embodiment has the features described below. [0053] 10 As stated above, the indoor unit 1 of the present embodiment is arranged so that the main blade 63 and the sub blade 64 of the turbofan 62 have the extension portions 63c and 64b, respectively. With this structure, the air flow in centrifugal direction, which is blown out 15 through the space between the main blade 63 and the sub blade 64, is directed to the upper outlet port 52a and the lower outlet port 52b by the extension portion 63c and the extension portion 64b. In other words, the indoor unit 1 is able to form a smooth air flow which heads for the 20 upper outlet port 52a and the lower outlet port 52b from the turbofan 62 in the casing unit 50, before colliding the bottom frame 53. This makes it possible to restrain the generation of noise on account of the collision of an air flow blown out from the turbofan 62 onto the bottom 25 frame 53. 23 [0054] In addition to the above, the indoor unit 1 of the present embodiment is arranged so that the extension portion 64b on the sub blade 64 side, where the air flow 5 is slow, is curved. This facilitates airflow to the upper outlet port 52a and the lower outlet port 52b. [0055] In addition to the above, the indoor unit 1 of the present embodiment is arranged so that the external 10 diameter Rl of the extension portion 63c is identical with the external diameter R2 of the extension portion 64b. This allows the extension portion 63c and the extension portion 64b to be efficiently extended in the casing unit 50 which defines the maximum size of the external diameter 15 of the turbofan 62. [0056] In addition to the above, the indoor unit 1 of the present embodiment is arranged so that the extension portion 63c is formed along the entirety of the outer 20 periphery of the main blade 63 and the extension portion 64b is formed along the entirety of the outer periphery of the sub blade 64. This structure allows the air flow blown out in centrifugal direction to be equally directed to the upper outlet port 52a and the lower outlet port 52b from 25 the entire outer peripheries of the main blade 63 and the 24 sub blade 64. [Examples] [0057] Fig. 13 is a graph showing the relationship between 5 an angle of inclination of the extension portion of the main blade of First Embodiment and noise. Fig. 14 is a graph showing the relationship between an angle of inclination of the extension portion of the main blade of First Embodiment and an input to the fan motor. 10 [0058] (Example 1) In Example 1, the angle theta of inclination (see Fig. 5) of the extension portion of the main blade was about 9 degrees. In this case, as shown in Fig. 13, the 15 generation of noise caused by the collision of wind blown out from the turbofan onto the casing or the like was restrained in Example 1, as compared to a comparative example of the conventional structure in which the main blade does not have the extension portion. Furthermore, 20 in Example 1, the input to the fan motor was slightly restrained as shown in Fig. 14. [0059] (Example 2) In Example 2, the angle theta of inclination (see 25 Fig. 5) of the extension portion of the main blade was 25 arranged to be about 18 degrees. In this case, as shown in Fig. 13, the generation of noise caused by the collision of wind blown out from the turbofan onto the casing or the like was restrained in Example 2, as 5 compared to the comparative example of the conventional structure in which the main blade does not have the extension portion. Furthermore, in Example 2, the input to the fan motor was slightly restrained as shown in Fig. 14. In Example 2, however, both the noise reduction and 10 the reduction in the input of the fan motor were less effective than Example 1. This is presumably because the increase in the angle of inclination of the extension portion narrowed the blowing path of the turbofan and hence the channel loss was increased. 15 [0060] (Second Embodiment) Fig. 15 is a schematic cross section of a turbofan according to Second Embodiment of the present invention. The following will describe the turbofan according to 20 Second Embodiment of the present invention with reference to Fig. 15. The turbofan 162 of Second Embodiment is different from the turbofan 62 of First Embodiment in the shape of an extension portion 164b of a sub blade 164. It is noted that the components other than the turbofan 162 25 in Second Embodiment are identical with those recited in 26 First Embodiment, and hence the same reference numerals are assigned to them and the descriptions thereof are not repeated. [0061] 5 The turbofan 162 of the present embodiment includes, as shown in Fig. 15, a main blade 163, a sub blade 164 opposing the main blade 164, and a plurality of blades 165 provided between the main blade 163 and the sub blade 164. The main blade 163 and the blade 165 will not be described 10 in the present embodiment because they are identical with the main blade 63 and the blade 65 of First Embodiment, respectively. [0062] In Second Embodiment, the sub blade 164 is provided 15 with an extension portion 164b which linearly extends from the outer periphery of the sub blade 164 toward the outside of the outer peripheries of the blades 165. In other words, Second Embodiment is arranged so that both of the extension portion 163c of the main blade 163 and the 20 extension portion 164b of the sub blade 164 linearly extend. The extension portion 164b is inclined away from the main blade 163. More specifically, the extension portion 164b is arranged to be close to the outlet ports 52a and 52b (see Fig. 3) toward its leading end. The 25 angle theta of inclination 101 of this extension portion 27 164b of the sub blade 164 is larger than the angle theta of inclination 102 of the extension portion 163c of the main blade 163. (0063] 5 (Third Embodiment) Fig. 16 is a schematic cross section of a turbofan according to Third Embodiment of the present invention. The following will describe the turbofan according to Third Embodiment of the present invention with reference 10 to Fig. 16. The turbofan 262 of Third Embodiment is arranged so that both of an extension portion 263c of a main blade 263 and an extension portion 264b of a sub blade 264 are curved. It is noted that the components other than the turbofan 262 in Third Embodiment are 15 identical with those recited in First Embodiment, and hence the same reference numerals are assigned to them and the descriptions thereof are not repeated. [0064] The turbofan 262 of the present embodiment includes, 20 as shown in Fig. 16, a main blade 263, a sub blade 264 opposing the main blade 263, and a plurality of blades 265 provided between the main blade 263 and the sub blade 264. The blades 265 will not be described because they are identical with the blades 65 of First Embodiment. 25 [0065] 28 According to Third Embodiment, as shown in Fig. 16, the main blade 263 is provided with an extension portion 263c which curves and extends from the outer periphery of the main blade 263 toward the outside of the outer 5 peripheries of the blades 265. This extension portion 263c is arranged to be close to the sub blade 264 toward its leading end. [0066] The sub blade 264 is provided with an extension 10 portion 264b which curves and extends from the outer periphery of the sub blade 264 toward the outside of the outer peripheries of the blades 265. In other words, in Third Embodiment both of the extension portion 263c of the main blade 263 and the extension portion 264b of the sub 15 blade 264 are curved. The extension portion 264b is inclined away from the main blade 263. More specifically, the extension portion 264b is arranged to be close to the outlet ports 52a and 52b (see Fig. 3) toward its leading end. The curvature of this extension portion 264b of the 20 sub blade 264 is greater that that of the extension portion 263c of the main blade 263. [0067] While the present invention has been described in conjunction with the specific embodiments outlined above, 25 it is evident that many alternatives, modifications and 29 variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the invention as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing 5 from the spirit and scope of the invention as defined in the following claims. [0068] For example, while the embodiments above describe the separated air conditioner including the outdoor unit 10 and the indoor unit, the present invention is applicable for integrated air conditioners. [0069] Also, First Embodiment is arranged so that the extension portion of the main blade is linear whereas the 15 extension portion of the sub blade is curved, Second Embodiment is arranged so that the extension portions of the main blade and the sub blade are both linear, and Third Embodiment is arranged so that the extension portions of the main blade and the sub blade are both 20 curved. In addition to this, the present invention may be arranged such that the extension portion of the main blade is curved whereas the extension portion of the sub blade is linear. [INDUSTRIAL APPLICABILITY] 25 [0070] 30 The present invention makes it possible to realize an indoor unit of a floor-type air conditioner, which is capable of restraining noise caused by the collision of air blown out from a centrifugal fan (turbofan) onto a 5 casing or the like. [0071] 1 INDOOR UNIT 50 CASING UNIT (CASING) 51a UPPER INLET PORT (INLET PORT) 10 51b LOWER INLET PORT (INLET PORT) 52a UPPER OUTLET PORT (OUTLET PORT) 52b LOWER OUTLET PORT (OUTLET PORT) 62, 162, 262 TURBOFAN (CENTRIFUGAL FAN) 63, 163, 263 MAIN BLADE 15 63c, 163c, 263c EXTENSION PORTION (FIRST EXTENSION PORTION) 64, 164, 264 SUB BLADE 64b, 164b, 264b EXTENSION PORTION (SECOND EXTENSION PORTION) 20 65, 165, 265 BLADE 31