Patent Publication Number: US-2012031983-A1

Title: Indoor unit of air-conditioning apparatus and air-conditioning apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an indoor unit having a fan and a heat exchanger housed in a casing and an air-conditioning apparatus having the indoor unit. 
     2. Description of the Related Art 
     Conventionally, an air-conditioning apparatus (more specifically, an indoor unit) having a vertical wind direction control vane divided into three parts and a horizontal wind direction control vane and configured to control the direction of an airflow blown out from a blow-out port using the vertical wind direction control vane divided into three parts and the horizontal wind direction control vane has been proposed. More specifically, two parts of the vertical wind direction control vane other than the central part are controlled in the closing direction of the blow-out port and the horizontal wind direction control vane is controlled to throttle the airflow blown out from the blow-out port, so that the velocity of the airflow blown out from the center of the blow-out port is increased. Accordingly, people present in a room are provided with more comfort (for example, see Japanese Unexamined Patent Application Publication No. 2001-153428). 
     The conventional air-conditioning apparatus controls the direction of the airflow blown out from the blow-out port using only the vertical wind direction control vane divided into three parts and the horizontal wind direction control vane. Therefore, distribution of airflows different in air volume individually to different places in the room were unfortunately not possible. 
     SUMMARY OF THE INVENTION 
     In order to solve the above-described problem, it is an object of the invention to provide an indoor unit of an air-conditioning apparatus, which is capable of distributing airflows different in air volume individually to different places in a room, and an air-conditioning apparatus having such an indoor unit. 
     An indoor unit of an air-conditioning apparatus according to the invention includes: a casing having a suction port formed on an upper portion and a blow-out port formed on a lower side of a front surface portion; a plurality of axial-flow or mixed-flow fans provided in parallel on the downstream side of the suction port in the casing; a heat exchanger provided on the downstream side of each fans and on the upstream side of each blow-out port in the casing and configured to exchange heat between air blown out from the fan and a refrigerant; a horizontal wind direction control vane provided at the blow-out port and configured to control the horizontal direction of an airflow blown out from the blow-out port; a vertical wind direction control vane provided at the blow-out port and configured to control the vertical direction of the airflow blown out from the blow-out port; and a human detection sensor configured to detect the position of a person present in a room, in which the air volume, the orientation of the horizontal wind direction control vane, and the orientation of the vertical wind direction control vane of each of the fans are each controlled according to detected results of the human detection sensor. 
     The air-conditioning apparatus according to the invention includes the indoor unit described above. 
     According to the invention, the situation in the room (for example, where a person is present) can be detected by the human detection sensor. Then, by controlling the air volume, the orientation of the horizontal wind direction control vane, and the orientation of the vertical wind direction control vane of each of the fans according to detected results of the human detection sensor, airflows of different air volumes can be distributed individually to different places in the room. Controlling each air volume of the fans does not mean to differ each of the air volumes of each fans. As a matter of course, the air volumes of some fans may be the same. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a vertical cross-sectional view illustrating an indoor unit of an air-conditioning apparatus according to Embodiment 1 of the invention. 
         FIG. 2  is a perspective view illustrating the indoor unit of the air-conditioning apparatus according to Embodiment 1 of the invention. 
         FIG. 3  is a front cross-sectional view illustrating the indoor unit according to Embodiment 1 of the invention. 
         FIG. 4  is a perspective view illustrating the indoor unit according to Embodiment 1 of the invention. 
         FIG. 5  is an explanatory drawing illustrating each light distribution view angles of light-receiving elements in an infrared ray sensor according to Embodiment 1 of the invention. 
         FIG. 6  is a perspective view illustrating a housing for accommodating the infrared ray sensor according to Embodiment 1 of the invention. 
         FIG. 7A  is an explanatory drawing illustrating a turning state of the infrared ray sensor according to Embodiment 1 of the invention. 
         FIG. 7B  is an explanatory drawing illustrating another turning state of the infrared ray sensor according to Embodiment 1 of the invention. 
         FIG. 7C  is an explanatory drawing illustrating still another turning state of the infrared ray sensor according to Embodiment 1 of the invention. 
         FIG. 8  is an explanatory drawing illustrating vertical light distribution view angles in a vertical cross section of the infrared ray sensor according to Embodiment 1 of the invention. 
         FIG. 9  shows an example of heat image data obtained by the infrared ray sensor according to Embodiment 1. 
         FIG. 10  shows an example in which the indoor unit according to Embodiment 1 divides a floor surface area in a room into a plurality of area blocks. 
         FIG. 11  is a front cross-sectional view illustrating the indoor unit according to Embodiment 2 of the invention. 
         FIG. 12  is a perspective view illustrating the indoor unit according to Embodiment 2 of the invention. 
         FIG. 13  is a front cross-sectional view illustrating the indoor unit according to Embodiment 3 of the invention. 
         FIG. 14  is a perspective view illustrating the indoor unit according to Embodiment 3 of the invention. 
         FIG. 15  is a perspective view of the indoor unit according to Embodiment 1 of the invention when viewed from the front right side. 
         FIG. 16  is a perspective view of the indoor unit according to Embodiment 1 of the invention when viewed from the rear right side. 
         FIG. 17  is a perspective view of the indoor unit according to Embodiment 1 of the invention when viewed from the front left side. 
         FIG. 18  is a perspective view illustrating a drain pan according to Embodiment 1 of the invention. 
         FIG. 19  is a vertical cross-sectional view illustrating a dew condensation forming position of the indoor unit according to Embodiment 1 of the invention. 
         FIG. 20  is a configuration drawing illustrating a signal processing device according to Embodiment 1 of the invention. 
         FIG. 21  is a vertical cross-sectional view illustrating another example of the indoor unit of the air-conditioning apparatus according to Embodiment 1 of the invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, detailed embodiments of an air-conditioning apparatus according to the invention (more specifically, an indoor unit of the air-conditioning apparatus) will be described. In the following embodiments, the invention will be described with a wall indoor unit taken as an example. In the drawings showing respective embodiments, part of the shapes or the sizes of each units (or the components of each units) may be different. 
     Embodiment 1 
     &lt;Basic Configuration&gt; 
       FIG. 1  is a vertical cross-sectional view illustrating an indoor unit (referred to as “indoor unit  100 ”) of an air-conditioning apparatus according to Embodiment 1 of the invention.  FIG. 2  is a perspective view illustrating the indoor unit shown in  FIG. 1 . In the description of Embodiment 1 and other embodiments described later, the left side in  FIG. 1  is defined as the front side of the indoor unit  100 . Referring now to  FIG. 1  and  FIG. 2 , a configuration of the indoor unit  100  will be described. 
     (General Configuration) 
     The indoor unit  100  supplies air-conditioned air to an area to be air-conditioned such as an indoor space by utilizing a refrigerating cycle circulating a refrigerant. The indoor unit  100  mainly includes a casing  1  formed with suction ports  2  for taking in indoor air and a blow-out port  3  for supplying air-conditioned air to the area to be air-conditioned, fans  20  housed in the casing  1  and configured to take in the indoor air from the suction ports  2  and blow out the air-conditioned air from the blow-out port  3 , and heat exchangers  50  disposed in air paths from the fans  20  to the blow-out port  3  and configured to generate the air-conditioned air by heat exchange between the refrigerant and the indoor air. In these components, each of the air paths (an arrow Z in  FIG. 1 ) communicates with the interior of the casing  1 . The suction ports  2  are formed so as to open at an upper portion of the casing  1 . The blow-out port  3  is formed so as to open at a lower portion of the casing  1  (more specifically, on the lower side of a front surface portion of the casing  1 ). The fans  20  are each disposed on the downstream side of the suction ports  2  and the upstream side of the heat exchangers  50 , and, for example, axial-flow fans or mixed-flow fans are employed. 
     The indoor unit  100  is provided with a control device  281  configured to control the rotation speeds of the fans  20 , the orientations (angles) of a later described vertical wind direction control vane  70  and a horizontal wind direction control vane  80  (if an auxiliary vertical wind direction control vane  71 , described later, is provided, the auxiliary vertical wind direction control vane  71  is also included), and so on. In some cases, illustration of the control device  281  may be omitted in drawings illustrating Embodiment 1 and other embodiments described later. 
     Since the fans  20  are provided on the upstream side of the heat exchangers  50  in the indoor unit  100  as configured above, generation of a swirl flow of air blown out from the blow-out port  3  and occurrence of variation in wind velocity distribution can be restrained in comparison with the indoor unit of the conventional air-conditioning apparatus having the fan  20  at the blow-out port  3 . Therefore, blowing of comfortable air to the area to be air-conditioned is achieved. Since no complex structure such as a fan is provided at the blow-out port  3 , measures against dew condensation formed at a boundary between warm air and cool air at the time of a cooling operation can easily be implemented. In addition, since a fan motor  30  is not exposed to air-conditioned air, namely, cool air or warm air, a long operational life can be provided. 
     (Fan) 
     In general, the indoor unit of the air-conditioning apparatus has limitations in terms of installation space, so the fan cannot be increased in size in many cases. Therefore, in order to obtain a desired air volume, a plurality of fans of moderate sizes are arranged in parallel. In the indoor unit  100  according to Embodiment 1, three fans  20  are arranged in parallel along the longitudinal direction of the casing  1  (that is, along the longitudinal direction of the blow-out port  3 ) as shown in  FIG. 2 . In order to obtain a desired heat-exchange capacity with the indoor unit of the air-conditioning apparatus having typical dimensions, three to four fans  20  are preferably provided. In the indoor unit according to Embodiment 1, substantially equivalent air volumes can be obtained from all of the fans  20  by configuring all of the fans  20  to have an identical shape and so as to operate all with the same rotation speed. 
     In this configuration, by combining the number, the shape, and the size of the fans  20  according to the required air volume and the air-flow resistance in the interior of the indoor unit  100 , an optimal fan design for the indoor units  100  having various specifications is achieved. 
     (Bell Mouth) 
     In the indoor unit  100  according to Embodiment 1, a duct-like bell mouth  5  is arranged around each of the fans  20 . The bell mouth  5  is intended to guide intake air into and exhaust air out of the fans smoothly. As shown in  FIG. 2 , for example, the bell mouth  5  according to Embodiment 1 has a substantially circular shape in plan view. In the vertical cross section, the bell mouth  5  according to Embodiment 1 has the following shape. An end portion of an upper portion  5   a  has a substantially circular arc shape extending outward and upward. A center portion  5   b  is a straight portion of the bell mouth  5 , having a constant diameter. An end portion of a lower portion  5   c  has a substantially circular arc shape extending outward and downward. An end portion (a circular arc portion on the suction side) of the upper portion  5   a  of the bell mouth  5  forms the suction port  2 . 
     The bell mouth  5  may be formed integrally with, for example, the casing  1  in order to reduce the number of components and improve the strength. It is also possible, for example, to improve maintainability by modularizing the bell mouth  5 , the fan  20 , and the fan motor  30  so as to be detachably attachable to the casing  1 . 
     In Embodiment 1, the end portion (the circular arc portion on the suction side) of the upper portion  5   a  of the bell mouth  5  is formed so as to have a uniform shape in terms of the circumferential direction of an opening surface of the bell mouth  5 . In other words, the bell mouth  5  does not have structures such as a notch or a rib in the direction of rotation about an axis of rotation  20   a  of the fan  20 , and has a uniform shape in terms of axial symmetry. 
     With the configuration of the bell mouth  5  as described above, the end portion (the circular arc portion on the suction side) of the upper portion  5   a  of the bell mouth  5  has a uniform shape with respect to the rotation of the fan  20 , and hence a uniform flow of the suction flow of the fan  20  is also realized. Therefore, the noise generated by a drift of the suction flow of the fan  20  can be decreased. 
     (Partitioning Panel) 
     As shown in  FIG. 2 , the indoor unit  100  according to Embodiment 1 is provided with partitioning panels  90  between the adjacent fans  20 . These partitioning panels  90  are installed between the heat exchangers  50  and the fans  20 . In other words, the air paths between the heat exchangers  50  and the fans  20  are divided into a plurality of air paths (three in Embodiment 1). The partitioning panels  90  are arranged between the heat exchangers  50  and the fans  20 , so each end portion that is in contact with the heat exchanger  50  has a shape conforming to the shape of the heat exchanger  50 . More specifically, as shown in  FIG. 1 , the heat exchanger  50  is arranged so as to form a substantially A-shape in a vertical cross section from the front side to the back side of the indoor unit  100  (that is, the vertical cross section when viewing the indoor unit  100  from the right side, referred to as “right vertical cross-section”, hereinafter). Therefore, an end portion of each of the partitioning panels  90  on the side of the heat exchanger  50  also has a substantially A-shape. 
     The position of an end portion of each of the partitioning panels  90  on the side of the fan  20  may be determined as follows, for example. When the adjacent fans  20  are positioned sufficiently away from each other to avoid influencing each other on the suction side, the end portion of each of the partitioning panels  90  on the side of the fan  20  may need only be extend to an exit surface of the fan  20 . However, in a case where the adjacent fans  20  are as near to each other to influence each other on the suction side and, in addition, in a case where the shape of the end portion (the circular arc portion on the suction side) of the upper portion  5   a  of the bell mouth  5  can be formed sufficiently large, the end portion of each of the partitioning panels  90  on the side of the fan  20  may extend up to the upstream side of the fan  20  (the suction side) so that the adjacent air paths do not influence each other (the adjacent fans  20  do not influence each other on the suction side). 
     The partitioning panels  90  may be formed of various materials. For example, the partitioning panels  90  may be formed of a metal such as steel or aluminum. Also, for example, the partitioning panels  90  may be formed of a resin. When the partitioning panels  90  are formed of a material with a low melting point such as a resin, however, since the heat exchangers  50  are heated to high temperatures at the time of a heating operation, formation of slight spaces between the partitioning panels  90  and the heat exchangers  50  is recommended. When the partitioning panels  90  are formed of a material with a high melting point such as aluminum or steel, the partitioning panels  90  may be arranged so as to be in contact with the respective heat exchangers  50 . If the heat exchangers  50  are, for example, fin and tube heat exchangers, the partitioning panels  90  may be inserted between the fins of the heat exchangers  50 . 
     As described above, the air path between the heat exchangers  50  and the fans  20  is divided into a plurality of air paths (three in Embodiment 1). It is also possible to reduce the noise generated in the ducts by providing sound-absorbing materials in these air paths, that is, on the partitioning panels  90  or in the casing  1 . 
     The divided air paths are each formed into a substantially square shape of L 1 ×L 2 . In other words, the widths of the divided air paths are L 1  and L 2 . Therefore, the air volume generated by the fan  20  installed in the interior of the substantially square shape of L 1 ×L 2 , for example, reliably passes through the heat exchanger  50  surrounded by an area defined by L 1  and L 2  on the downstream side of the fan  20 . 
     By dividing the air path in the casing  1  into the plurality of air paths as described above, even when the flow field which is generated by the fan  20  on the downstream side has a swirling component, air blown out from each of the fans  20  is prevented from moving freely in the longitudinal direction of the indoor unit  100  (the direction orthogonal to the plane of the paper of  FIG. 1 ). Therefore, the air blown out from the fan  20  can be made to pass through the heat exchanger  50  in the area defined by L 1  and L 2  on the downstream side of the fan  20 . Consequently, variations in air volume distribution of the air flowing into all the heat exchangers  50  in the longitudinal direction of the indoor unit  100  (the direction orthogonal to the plane of the paper of  FIG. 1 ) is restrained, so that a high heat exchanging capacity can be provided. Furthermore, by partitioning the interior of the casing  1  by using the partitioning panels  90 , the mutual interference of the swirl flows generated by the adjacent fans  20  can be prevented between the fans  20  adjacent to each other. Therefore, an energy loss of fluid due to the mutual interference of the swirl flows can be prevented, and hence reduction of a pressure loss in the indoor unit  100  is possible in addition to the improvement in the wind velocity distribution. Each of the partitioning panels  90  does not necessarily have to be formed of a single plate, and may be made up of a plurality of plates. For example, the partitioning panel  90  may be divided into two parts on the side of a front heat exchanger  51  and on the side of a back side heat exchanger  55 . Needless to say, it is preferable that no gap be formed at a joint portion between the respective plates which constitute the partitioning panel  90 . By dividing the partitioning panel  90  into a plurality of plates, assemblability of the partitioning panels  90  is improved. 
     (Fan Motor) 
     The fan  20  is driven and rotated by the fan motor  30 . The fan motor  30  to be used may be either of an inner-rotor type or an outer-rotor type. In the case of the fan motor  30  of the outer-rotor type, a motor having a structure in which a rotor is integrated with a boss  21  of the fan  20  (the rotor is held by the boss  21 ) is also employed. By setting the dimensions of the fan motor  30  to be smaller than the dimensions of the boss  21  of the fan  20 , loss of airflow generated by the fan  20  can be prevented. In addition, by disposing the motor in the interior of the boss  21 , an axial dimension can also be reduced. With the easily detachable and attachable structure of the fan motor  30  and the fan  20 , cleanability is also improved. 
     By using a Brushless DC motor which is relatively high in cost as the fan motor  30 , improvement in efficiency, elongation of service life, and improvement in controllability are achieved. Needless to say, however, a primary function of an air-conditioning apparatus is achieved even when motors of other types are employed. 
     A circuit for driving the fan motor  30  may be integrated with the fan motor  30 , or may be provided externally for dust-proofing measures and fire prevention measures. 
     The fan motor  30  is attached to the casing  1  using a motor stay  16 . In addition, by configuring the fan motor  30  to be of a box-type fan motor (in which the fan  20 , a housing, and the fan motor  30  are integrally modularized) used for cooling a CPU and configuring the fan motor  30  so as to be detachably attached to the motor stay  16 , maintainability can be improved, and accuracy of tip clearance of the fan  20  can also be improved. 
     A drive circuit of the fan motor  30  may be provided either in the interior of or on the exterior of the fan motor  30 . 
     (Motor Stay) 
     The motor stay  16  is provided with a fixing member  17  and supporting members  18 . The fixing member  17  is a member to which the fan motor  30  is attached. The supporting members  18  are members configured to fix the fixing member  17  to the casing  1 . The supporting members  18  are, for example, rod-shaped members, and extend, for example, radially from an outer peripheral portion of the fixing member  17 . As shown in  FIG. 1 , the supporting members  18  according to Embodiment 1 are extend approximately horizontally. 
     (Heat Exchanger) 
     The heat exchangers  50  of the indoor unit  100  according to Embodiment 1 are arranged on the downstream sides of the fans  20 . Fin and tube heat exchangers are preferably used as the heat exchangers  50 . The heat exchangers  50  are each divided by a line of symmetry  50   a  in the right vertical cross section as shown in  FIG. 1 . The line of symmetry  50   a  divides the area substantially in the center in the horizontal direction of which the heat exchanger  50  is installed in this cross section. In other words, the front side heat exchanger  51  is arranged on the front side (the left side in the plane of the paper in  FIG. 1 ) with respect to the line of symmetry  50   a  and the back side heat exchanger  55  is arranged on the back side (the right side in the plane of the paper in  FIG. 1 ) with respect to the line of symmetry  50   a , respectively. The front side heat exchanger  51  and the back side heat exchanger  55  are arranged in the casing  1  so that the distance between the front side heat exchanger  51  and the back side heat exchanger  55  increases in the direction of an air current, that is, so that the cross-sectional shape of the heat exchanger  50  forms a substantially inverted V-shape in the right vertical cross section. In other words, the front side heat exchanger  51  and the back side heat exchanger  55  are arranged so as to be inclined with respect to the direction of the air current supplied from the fan  20 . 
     In addition, the heat exchanger  50  is characterized in that the air path area of the back side heat exchanger  55  is larger than the air path area of the front side heat exchanger  51 . In other words, the heat exchanger  50  is arranged so that the air volume of the back side heat exchanger  55  is larger than the air volume of the front side heat exchanger  51 . In Embodiment 1, the length of the back side heat exchanger  55  in the longitudinal direction is larger than the length of the front side heat exchanger  51  in the longitudinal direction in the right vertical cross section. Accordingly, the air path area of the back side heat exchanger  55  is larger than the air path area of the front side heat exchanger  51 . The rest of the configuration (such as the lengths in the depth direction in  FIG. 1 ) of the front side heat exchanger  51  and that of the back side heat exchanger  55  are the same. In other words, the heat conduction area of the back side heat exchanger  55  is larger than the heat conduction area of the front side heat exchanger  51 . Also, the axis of rotation  20   a  of the fan  20  is arranged above the line of symmetry  50   a.    
     With the configuration of the heat exchanger  50  as described above, the generation of the swirl flow of the air blown out from the blow-out port  3  and the occurrence of a variation in wind velocity distribution can be restrained in comparison with the indoor unit of the conventional air-conditioning apparatus having the fan at the blow-out port. Also, with the configuration of the heat exchanger  50  as described above, the air volume of the back side heat exchanger  55  is larger than the air volume of the front side heat exchanger  51 . Because of this difference in air volume, when air currents having passed through the front side heat exchanger  51  and the back side heat exchanger  55  merge, the merged air current is curved toward the front side (the side of the blow-out port  3 ). Therefore, necessity to curve the airflow steeply in the vicinity of the blow-out port  3  is eliminated, and hence the pressure loss in the vicinity of the blow-out port  3  can be reduced. 
     In the indoor unit  100  according to Embodiment 1, the air current flowing out from the back side heat exchanger  55  flows in the direction from the back side to the front side. Therefore, in the indoor unit  100  according to Embodiment 1, the air current after having passed the heat exchanger  50  can be curved more easily than in the case where the heat exchanger  50  is arranged in a substantially V-shape in the right vertical cross section. 
     The indoor unit  100  includes the plurality of fans  20 , which often results in an increase in weight. When the weight of the indoor unit  100  increases, a wall surface strong enough for installing the indoor unit  100  is required, which leads to a restriction of installation. Therefore, reduction of weight of the heat exchanger  50  is preferred. In addition, in the indoor unit  100 , since the fans  20  are arranged on the upstream sides of the heat exchangers  50 , the height of the indoor unit  100  is increased, which often leads to a restriction of installation. Therefore, downsizing of the heat exchanger  50  is preferred. 
     Accordingly, in Embodiment 1, the fin and tube heat exchanger is employed as the heat exchanger  50  (the front side heat exchanger  51  and the back side heat exchanger  55 ) to achieve downsize of the heat exchanger  50 . More specifically, the heat exchanger  50  according to Embodiment 1 includes a plurality of fins  56  arranged side by side with predetermined gaps therebetween and a plurality of heat-transfer tubes  57  penetrating through the fins  56 . In Embodiment 1, the fins  56  are arranged side by side in the horizontal direction of the casing  1  (the direction orthogonal to the plane of the paper of  FIG. 1 ). In other words, the heat-transfer tubes  57  penetrate through the fins  56  along the horizontal direction of the casing  1  (the direction orthogonal to the plane of the paper of  FIG. 1 ). In Embodiment 1, in order to improve heat-transfer efficiency of the heat exchanger  50 , two rows of the heat-transfer tubes  57  are arranged in the direction of air flow of the heat exchanger  50  (the width direction of the fins  56 ). The heat-transfer tubes  57  are arranged in a substantially zigzag shape in right vertical cross section. 
     Downsizing of the heat exchanger  50  is achieved by configuring the heat-transfer tubes  57  with circular tubes having a small diameter (on the order of diameters ranging from 3 mm to 7 mm), and employing R32 as the refrigerant flowing through the heat-transfer tubes  57  (the refrigerant used in the indoor unit  100  and in the air-conditioning apparatus having the indoor unit  100 ). In other words, the heat exchanger  50  exchanges heat between the refrigerant flowing in the interiors of the heat-transfer tubes  57  and the indoor air via the fins  56 . Therefore, when the diameter of the heat-transfer tubes  57  is reduced, with the same amount of circulation of the refrigerant, the pressure loss of the refrigerant is larger than that of the heat exchanger provided with heat-transfer tubes having a large diameter. However, the latent heat of evaporation of R32 is higher than that of R410A at the same temperature, and hence the same capacity can be obtained with a smaller amount of circulation of the refrigerant. Therefore, by using R32, reduction of the amount of a refrigerant to be used is made possible, and the pressure loss in the heat exchanger  50  can be reduced. Therefore, by employing thin circular tubes as the heat-transfer tubes  57 , and using R32 as the refrigerant, downsizing of the heat exchanger  50  is achieved. 
     Furthermore, in the heat exchanger  50  according to Embodiment 1, a reduction in the weight of the heat exchanger  50  is achieved by forming the fins  56  and the heat-transfer tubes  57  with aluminum or aluminum alloy. And if the weight of the heat exchanger  50  does not cause a restriction of installation, the heat-transfer tubes  57  may be formed of copper as a matter of course. 
     (Finger Guard and Filter) 
     The indoor unit  100  according to Embodiment 1, a finger guard  15  and a filter  10  are provided at the suction port  2 . The finger guard  15  is installed for the purpose of preventing the rotating fan  20  from being touched. Therefore, the shape of the finger guard  15  is arbitrary as long as the fan  20  is prevented from being touched. For example, the shape of the finger guard  15  may be a lattice shape, or may be a circular shape made up of a number of rings having different sizes. Alternatively, the finger guard  15  may be formed either of materials such as resin or metallic materials, However, when strength is required, it is preferably formed of metal. The finger guard  15  is preferably formed of materials and shapes as strong and thin as possible in terms of reduction of air-flow resistance and retention of strength. The filter  10  is provided for the purpose of preventing dust from flowing into the interior of the indoor unit  100 . The filter  10  is provided in the casing  1  so as be detachable and attachable. The indoor unit  100  according to Embodiment 1 includes an automatic cleaning mechanism which cleans the filter  10  automatically. 
     (Wind Direction Control Vane) 
     The indoor unit  100  according to Embodiment 1 includes a vertical wind direction control vane  70  and a horizontal wind direction control vane  80 , which are mechanisms for controlling the blowing direction of the airflow, at the blow-out port  3 . In Embodiment 1, the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are controlled together with the air volumes of each fans  20  on the basis of detected results of the human detection sensor. Accordingly, airflow controllability of the indoor unit  100  can be improved. 
       FIG. 3  is a front cross-sectional view illustrating the indoor unit according to Embodiment 1 of the invention.  FIG. 4  is a perspective view illustrating the same indoor unit.  FIG. 3  is a front cross-sectional view taken along the substantially center portions of the fans  20 . The indoor unit  100  shown in  FIG. 3  and  FIG. 4  show the indoor unit  100  having the three fans  20  (fan  20 A to fan  20 C). 
     The horizontal wind direction control vane  80  is coupled to a motor  81 , such as a stepping motor, via a link rod  82 . By the motor  81  driven according to the number of steps commanded by the control device  281 , the orientation (angle) of the horizontal wind direction control vane  80  is changed and the direction of airflow blown out from the blow-out port  3  can be controlled in the horizontal direction. The vertical wind direction control vane  70  is coupled to a motor (not shown) such as a stepping motor. By this motor driven according to the number of steps commanded by the control device  281 , the orientation (angle) of the vertical wind direction control vane  70  is changed and the direction of airflow blown out from the blow-out port  3  can be controlled in the vertical direction. 
     In the indoor unit  100  according to Embodiment 1, a human detection sensor configured to detect the position of a person present in a room is provided. As a human detection sensor, various types such as a human detection sensor using a camera may be used. In Embodiment 1, an infrared ray sensor  410  is used as the human detection sensor. The infrared ray sensor  410  is configured to scan the area of the room subject to the detection of temperature and detect the temperature of the area of the room subject to the detection of temperature, and detect the presence of a person, a heat generating equipment, or the like. 
     The infrared ray sensor  410  is provided on the lower portion of a front surface of the casing  1  above the blow-out port  3 . The infrared ray sensor  410  is rotatable in the horizontal direction, and is attached so as to face downward at a depression angle of approximately 24.5 degrees. Here, the depression angle means an angle of a center axis of the infrared ray sensor  410  with respect to a horizontal line. In other words, the infrared ray sensor  410  is attached so as to face downward at an angle of approximately 24.5 degrees with respect to the horizontal line. 
       FIG. 5  is an explanatory drawing illustrating each light distribution view angles of a light-receiving element in the infrared ray sensor according to Embodiment 1 of the invention. 
     As shown in  FIG. 5 , the infrared ray sensor  410  includes eight light-receiving elements (not shown) arranged in a line in the vertical direction in a metallic container  411 . Provided on an upper surface of the metallic container  411  is a window (not shown) formed of a lens for allowing infrared rays to pass through to the eight light-receiving elements. Light distribution view angles  412  of each light-receiving elements are 7 degrees in the vertical direction and 8 degrees in the horizontal direction. Although the configuration in which the light distribution view angles  412  of each light-receiving elements are 7 degrees in the vertical direction and 8 degrees in the horizontal direction is shown in Embodiment 1, the light distribution view angles  412  are not limited to these values (7 degrees in the vertical direction and 8 degrees in the horizontal direction). The number of the light-receiving elements can be changed according to the light distribution view angles  412  of each light-receiving elements. For example, the light distribution view angles may be determined so that the product of vertical light distribution view angles of a single light-receiving element and the number of light-receiving elements become constant. 
       FIG. 6  is a perspective view illustrating the housing for accommodating the infrared ray sensor according to Embodiment 1 of the invention.  FIG. 6  is a perspective view of a portion near the infrared ray sensor  410  viewed from the back side (from inside the casing  1 ). 
     As shown in  FIG. 6 , the infrared ray sensor  410  is housed in the interior of a housing  413 . Provided above the housing  413  is a motor  414  configured to drive the infrared ray sensor  410  (more specifically, to rotate the infrared ray sensor  410  in the horizontal direction). The motor  414  is, for example, a stepping motor. Mounting portions  415  formed integrally with the housing  413  are fixed to the lower portion of the front surface of the casing  1 , so that the infrared ray sensor  410  is attached to the casing  1 . In a state in which the infrared ray sensor  410  is attached to the casing  1 , the motor  414  and the housing  413  are substantially vertical. Subsequently, the infrared ray sensor  410  is attached to the interior of the housing  413  so as to face downward at a depression angle of approximately 24.5 degrees. 
     The infrared ray sensor  410  is driven by the motor  414  so as to rotate within a predetermined angular range in the horizontal direction (the rotary drive like this is referred to as “turn”, here). More specifically, the infrared ray sensor  410  is turned as shown in  FIGS. 7A to 7C . 
       FIG. 7A  is an explanatory drawing illustrating a turning state of the infrared ray sensor according to Embodiment 1 of the invention,  FIG. 7B  is an explanatory drawing illustrating another turning state of the infrared ray sensor according to Embodiment 1 of the invention, and  FIG. 7C  is an explanatory drawing illustrating still another turning state of the infrared ray sensor according to Embodiment 1 of the invention.  FIG. 7A , here, is a perspective view illustrating a state in which the infrared ray sensor is turned to the left end (the right end in a state of viewing indoors from inside the indoor unit  100 ).  FIG. 7B  is a perspective view illustrating a state in which the infrared ray sensor is turned to a center portion.  FIG. 7C  is a perspective view illustrating a state in which the infrared ray sensor is turned to the right end (the left end in the state of viewing indoors from inside the indoor unit  100 ). 
     The infrared ray sensor  410  is turned from the left end ( FIG. 7A ) through the center portion ( FIG. 7B ) to the right end ( FIG. 7C ), and when it reaches the right end ( FIG. 7C ), it is inverted in direction and turns in the reverse direction. By repeating actions as described above, the infrared ray sensor  410  detects the temperature of the area subject to the detection of temperature while scanning the area of the room subject to the detection of temperature in the horizontal direction. 
     Here, a method of acquiring heat image data of a wall, a floor, or the like of a room using the infrared ray sensor  410  will be described. Control of the infrared ray sensor  410  and the like is performed by the control device  281  in which predetermined actions are programmed (for example, a microcomputer). In the following description, the expression “performed by the control device  281 ” for each control is omitted. 
     When acquiring the heat image data such as the wall, the floor, or the like of a room, the infrared ray sensor  410  is turned in the horizontal direction by the motor  414 , and the infrared ray sensor  410  is stopped for a predetermined period (0.1 to 0.2 seconds) at each position at every 1.6 degree of turning angle of the motor  414  (the angle of rotary drive of the infrared ray sensor  410 ). After every stop of the infrared ray sensor  410  at each position, the infrared ray sensor  410  is held as-is for a predetermined period (a period shorter than 0.1 to 0.2 seconds) to acquire the results of detection (heat image data) of the eight light-receiving elements of the infrared ray sensor  410 . After having acquired the results of detection of the infrared ray sensor  410 , the motor  414  is driven (at a turning angle of 1.6 degrees) again and then is stopped, and the results of detection (heat image data) of the eight light-receiving elements of the infrared ray sensor  410  are acquired with the same actions. 
     The above-described operation is performed repeatedly, and the heat image data in a detecting area are calculated on the basis of the results of detection of the infrared ray sensor  410  at 94 points in the horizontal direction. Since the heat image data is acquired by stopping the infrared ray sensor  410  at 94 points at every 1.6 degrees of turning angle of the motor  414 , the turning range of the infrared ray sensor  410  in the horizontal direction (the angular range of rotary drive in the horizontal direction) is approximately 150.4 degrees. 
       FIG. 8  is an explanatory drawing illustrating the vertical light distribution view angles in a vertical cross section of the infrared ray sensor according to Embodiment 1 of the invention.  FIG. 8  shows the vertical light distribution view angles in the vertical cross section of the infrared ray sensor  410  having the eight light-receiving elements arranged in a row in the vertical direction, in a state in which the indoor unit  100  is installed at a height of 1800 mm from the floor surface of the room. The angle 7 degrees shown in  FIG. 8  is the vertical light distribution view angle of a single light-receiving element. 
     The angle of 37.5 degrees in  FIG. 8  shows an area out of the vertical view angle area of the infrared ray sensor  410  (an angle from the wall on which the indoor unit  100  is attached). If the depression angle of the infrared ray sensor  410  is 0 degree, this angle is 90 degrees−4 (the number of light-receiving elements positioned below the horizontal line)×7 degrees (the vertical light distribution view angle of a single light-receiving element)=62 degrees, since the depression angle of the infrared ray sensor  410  according to Embodiment 1 is 24.5 degrees, this angle is 62 degrees−24.5 degrees=37.5 degrees. 
     By using the infrared ray sensor  410  configured as above, the heat image data as shown below, for example, may be acquired. 
       FIG. 9  shows an example of the heat image data acquired by the infrared ray sensor according to Embodiment 1.  FIG. 9  shows a result obtained by calculating the heat image data on the basis of the results of detection acquired while causing the infrared ray sensor  410  to turn in the horizontal direction in a daily instance in which a housewife  416  holds an infant  417  in her arms in a room measuring eight tatami mats (13.2 square meters). 
       FIG. 9  shows a heat image data acquired on a cloudy day in winter. Therefore, the temperature of a window  418  is as low as 10 to 15 degree C. In contrast, the temperatures of the housewife  416  and the infant  417  are the highest. In particular, the upper body temperatures of the housewife  416  and the infant  417  range from 26 to 30 degree C. By turning the infrared ray sensor  410  in the horizontal direction in this manner, the temperature information relating to each part of the room, for example, can be obtained. 
     The indoor unit  100  according to Embodiment 1, then controls the air volumes of each fans  20 , the orientation of the vertical wind direction control vane  70 , and the orientation of the horizontal wind direction control vane  80  on the basis of the temperature information of each part of the room obtained by the infrared ray sensor  410 . More specifically, the control device  281  provided in the indoor unit  100  is provided with an input unit, a CPU, a memory, and an output unit. In addition, the CPU includes an indoor state gauging unit, a target area determining unit, an area wind direction control unit integrated in the interior thereof. The control device  281  divides the floor surface area in the room into a plurality of area blocks, and replaces each coordinate points of the heat image data acquired by the infrared ray sensor  410  with these plurality of area blocks. Accordingly, the area blocks in the room where a person is present can be recognized with high degree of accuracy. 
       FIG. 10  shows an example in which the indoor unit according to Embodiment 1 divides the floor surface area in the room into the plurality of area blocks. 
     For example, the control device  281  of the indoor unit  100  divides the floor surface area in the room into fifteen area blocks, namely A 1  to E 3 . Then, the control device  281  controls the orientations of the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  on the basis of the heat source data acquired from the infrared ray sensor  410 . The control device  281  also controls the air volumes of each fans  20  on the basis of the heat source data acquired from the infrared ray sensor  410 . 
     For example, when the airflow blown out from the blow-out port  3  needs to be distributed far, the rotation speed of all the fans  20  are increased (the air volumes of all the fans  20  are increased), and the air volume blown out from the blow-out port  3  is increased. Also, for example, when the airflow blown out from the blow-out port  3  needs to be distributed very close to the indoor unit  100 , the revolution speed of all the fans  20  are decreased (the air volumes of all the fans  20  are decreased), and the air volume blown out from the blow-out port  3  is decreased. 
     Also, for example, there are instances when intensive air-conditioning is desired in an area block where a person is present even when the room temperature is close to its set temperature. In such a case, the air volume (that is, the rotation speed) of the fan  20  which generates an airflow reaching a place where the intensive air-conditioning is desired (the area block where a person is present) is increased. At this time, the remaining fans  20  may be operated at a low rotation speed or may be stopped. By controlling the air volumes of each fans  20  in this manner, the airflow can be distributed intensively to an area block where a person is present although the air volume of the entire airflow blown out from the blow-out port  3  of the indoor unit  100  is small. Accordingly, the temperature environment in the area block where a person is present can be further maintained, and comfortable and energy-saving operation of the indoor unit  100  can be realized. 
     Also, for example, there may be some who want to keep away from the airflow blown out from the blow-out port  3  of the indoor unit  100 . In this manner, if there is an area where avoidance of the airflow blown out from the blow-out port  3  of the indoor unit  100  is desired, the air volume (that is, the rotation speed) of the fan  20  which generates the airflow reaching the place where the avoidance of the airflow blown out from the blow-out port  3  is desired is decreased. By controlling the air volumes of each fans  20  in this manner, the air conditioning in the room can be performed while restraining the airflow blown out from the blow-out port  3  from reaching the corresponding place. Accordingly, the comfortable and energy-saving operation of the indoor unit  100  can be realized while maintaining the environment of the place where avoidance of the airflow blown out from the blow-out port  3  of the indoor unit  100  is desired. 
     When controlling the air volumes of each fans  20  individually as described above, the fan  20  to generate the airflow reaching the “place where intensive air-conditioning is desired” or the “place where avoidance of the airflow blown out from the blow-out port  3  is desired” may be assigned to the fan  20  which is closest to the corresponding place. For example, when the area block E 3  shown in  FIG. 10  corresponds to the place as described above, the fan  20  which is to generate an airflow reaching the area block E 3  may be assigned to the fan  20 C (see  FIG. 3 ). By selecting the fan  20  in this manner, the overall airflow blown out from the blow-out port  3  of the indoor unit  100  can be distributed to the substantially center portion in the room, so that further energy-saving operation of the indoor unit  100  can be realized. 
     (Drain Pan) 
       FIG. 15  is a perspective view of the indoor unit according to Embodiment 1 of the invention when viewed from the front right side.  FIG. 16  is a perspective view of the same indoor unit when viewed from the back right side.  FIG. 17  is a perspective view of the same indoor unit when viewed from the front left side.  FIG. 18  is a perspective view illustrating a drain pan according to Embodiment 1 of the invention. In order to facilitate understanding of the shape of the drain pan, the right side of the indoor unit  100  is shown in cross section in  FIG. 15  and  FIG. 16 , and the left side of the indoor unit  100  is shown in cross section in  FIG. 17 . 
     Provided below a lower end portion of the front side heat exchanger  51  (a front side end portion of the front side heat exchanger  51 ) is a front side drain pan  110 . Provided below a lower end portion of the back side heat exchanger  55  (a back side end portion of the back side heat exchanger  55 ) is a back side drain pan  115 . In Embodiment 1, the back side drain pan  115  and a back side portion  1   b  of the casing  1  are integrally formed. In the back side drain pan  115 , connecting ports  116  to which a drain hose  117  is connected are provided on both a left side end portion and a right side end portion. It is not necessary to connect the drain hose  117  to both of the connecting ports  116 , and the drain hose  117  may be connected to one of the connecting ports  116 . For example, when drawing of the drain hose  117  to the right side of the indoor unit  100  is desired at the time of installation of the indoor unit  100 , the drain hose  117  is connected to the connecting port  116  provided on the right side end portion of the back side drain pan  115 , and the connecting port  116  provided on the left side end portion of the back side drain pan  115  may be closed with a rubber cap or the like. 
     The front side drain pan  110  is arranged at a position higher than the back side drain pan  115 . Provided between the front side drain pan  110  and the back side drain pan  115  on both of the left side end portion and the right side end portion are drain channels  111  which correspond to drain flow channels. The drain channels  111  are each connected at an end portion on the front side thereof to the front side drain pan  110 , and are provided so as to incline downward from the front side drain pan  110  toward the back side drain pan  115 . Also, formed at end portions of the drain channels  111  on the back side are tongue portions  111   a . The end portions of the drain channels  111  on the back side are arranged so as to extend over an upper surface of the back side drain pan  115 . 
     When the indoor air is cooled by the heat exchangers  50  at the time of cooling operation, dew condensation forms on the heat exchangers  50 . Then, dew on the front side heat exchanger  51  drops from the lower end portion of the front side heat exchanger  51 , and is collected by the front side drain pan  110 . Dew on the back side heat exchanger  55  drops from the lower end portion of the back side heat exchanger  55 , and is collected by the back side drain pan  115 . 
     Since the front side drain pan  110  is provided at a position higher than the back side drain pan  115  in Embodiment 1, the drain water collected by the front side drain pan  110  flows through the drain channel  111  toward the back side drain pan  115 . Then, the drain water drops down from the tongue portion  111   a  of the drain channel  111  to the back side drain pan  115 , and is collected by the back side drain pan  115 . The drain water collected by the back side drain pan  115  passes through the drain hose  117 , and is drained to the outside of the casing  1  (the indoor unit  100 ). 
     As in Embodiment 1, by providing the front side drain pan  110  at a position higher than the back side drain pan  115 , the drain water collected by both of the drain pans can be gathered in the back side drain pan  115  (the drain pan arranged on the backmost side of the casing  1 ). Therefore, by providing the connecting port  116  of the drain hose  117  in the back side drain pan  115 , the drain water collected in the front side drain pan  110  and the back side drain pan  115  can be drained to the outside of the casing  1 . When performing maintenance (cleaning of the heat exchangers  50  and the like) of the indoor unit  100  by opening the front side portion or the like of the casing  1 , there is, therefore, no need to detach and attach the drain pan having the drain hose  117  connected thereto, thus workability such as maintenance is improved. 
     Since the drain channels  111  are provided on both the left side end portion and the right side end portion, even when the indoor unit  100  is installed in an inclined state, the drain water collected in the front side drain pan  110  can be guided reliably to the back side drain pan  115 . Since the connecting ports to which the drain hoses  117  are to be connected are provided on both the left side end portion and the right side end portion, the drawing direction of the hose can be selected according to the conditions of the indoor unit  100  in installation, so that workability when installing the indoor unit  100  is improved. Also, since the drain channels  111  are provided so as to extend over the back side drain pan  115  (that is, since a connecting mechanism is not necessary between the drain channel  111  and the back side drain pan  115 ), attachment and detachment of the front side drain pan  110  is facilitated, and hence maintainability is further improved. 
     It is also possible to connect the back side end of the drain channels  111  to the back side drain pan  115  and arrange the drain channels  111  so that the front side drain pan  110  extends over the drain channels  111 . In this configuration as well, the same effects as the configuration in which the drain channels  111  are arranged so as to extend over the back side drain pan  115  are achieved. The front side drain pan  110  does not necessarily have to be provided at a higher position than the back side drain pan  115 , and the drain water collected in both drain pans can be drained from the drain hose connected to the back side drain pan  115  even when the front side drain pan  110  and the back side drain pan  115  are provided at the same level. 
     (Nozzle) 
     The indoor unit  100  according to Embodiment 1 is configured in such a manner that an opening length d 1  of a nozzle  6  on the suction side (a throttle length d 1  between the drain pans defined by a portion between the front side drain pan  110  and the back side drain pan  115 ) is defined to be larger than an opening length d 2  (the length of the blow-out port  3 ) of the nozzle  6  on the blow-out side. In other words, the nozzle  6  of the indoor unit  100  has opening lengths which satisfy d 1 &gt;d 2 . 
     The reason why the nozzle  6  is configured to have opening lengths of d 1 &gt;d 2  is as follows. Since the value d 2  affects the distribution distance of the airflow, which is one of basic functions of the indoor unit, the opening length d 2  of the indoor unit  100  according to Embodiment 1 is assumed to be a comparable length with the blow-out port of the conventional indoor unit in the description given below. 
     By setting the dimensions of the nozzle  6  in the vertical cross section to be d 1 &gt;d 2 , the air path is widened, and an angle A of the heat exchanger  50  arranged on the upstream side (the angle formed between the front side heat exchanger  51  an the back side heat exchanger  55  on the downstream side of the heat exchanger  50 ) can be widened. Therefore, the wind velocity distribution generated in the heat exchanger  50  is reduced, and the air path of the downstream side of the heat exchanger  50  can be widened, whereby reduction of pressure loss in the entire indoor unit  100  can be achieved. In addition, the deviation of the wind velocity distribution generated in the vicinity of the inlet portion of the nozzle  6  can be unified and guided to the blow-out port by the effect of flow contraction. 
     For example, when the deviation of the wind velocity distribution generated in the vicinity of the inlet portion of the nozzle  6  (for example, a flow deviated toward the back side) is reflected directly in the deviation of the wind velocity distribution at the blow-out port  3 . In other words, when d 1 =d 2 , air is blown out from the blow-out port  3  still having the deviation in the wind velocity distribution. When d 1 &lt;d 2  is satisfied, for example, the contraction flow loss is increased when airflows passed through the front side heat exchanger  51  and the back side heat exchanger  55  merge in the vicinity of the inlet portion of the nozzle  6 . Therefore, when d 1 &lt;d 2  is satisfied, a loss corresponding to the contraction flow loss is generated unless otherwise a diffusion effect at the blow-out port  3  cannot be obtained. 
     (ANC) 
     In the indoor unit  100  according to Embodiment 1, an active silencing mechanism is provided as shown in  FIG. 1 . 
     More specifically, the silencing mechanism of the indoor unit  100  according to Embodiment 1 includes a noise detection microphone  161 , a control speaker  181 , a silencing effect detection microphone  191 , and a signal processing device  201 . The noise detection microphone  161  is a noise detection device configured to detect an operation sound (noise) of the indoor unit  100  including a blast sound of the fan  20 . The noise detection microphone  161  is arranged between the fan  20  and the heat exchanger  50 . In Embodiment 1, the noise detection microphone  161  is provided on the front surface portion in the casing  1 . The control speaker  181  is a control sound output device configured to output a control sound with respect to the noise. The control speaker  181  is arranged below the noise detection microphone  161  and above the heat exchanger  50 . In Embodiment 1, the control speaker  181  is provided on the front surface portion in the casing  1  so as to face the center of the air path. The silencing effect detection microphone  191  is a silencing effect detection device configured to detect the silencing effect using the control sound. The silencing effect detection microphone  191 , being intended to detect a noise coming from the blow-out port  3 , is provided in the vicinity of the blow-out port  3 . The silencing effect detection microphone  191  is attached at a position avoiding the airflow so as not to be exposed to the air coming out from the blow-out port  3 . The signal processing device  201  is a control sound generating device configured to cause the control speaker  181  to output the control sound on the basis of the results of detection by the noise detection microphone  161  and the silencing effect detection microphone  191 . The signal processing device  201  is housed, for example, in the control device  281 . 
       FIG. 20  is a configuration drawing illustrating a signal processing device according to Embodiment 1 of the invention. Electric signals supplied from the noise detection microphone  161  and the silencing effect detection microphone  191  are amplified by a microphone amplifier  151 , and are converted from analogue signals to digital signals by an A/D converter  152 . The converted digital signals are input to an FIR filter  158  and an LMS algorithm  159 . In the FIR filter  158 , a control signal, which is corrected to cause a noise with the same amplitude as and an opposite phase from the detected noise by the noise detection microphone  161  when the noise reaches a position where the silencing effect detection microphone  191  is installed, and is converted from a digital signal to an analogue signal by an D/A converter  154 , then is amplified by an amplifier  155 , and then is emitted as the control sound from the control speaker  181 . 
     In a case where the air-conditioning apparatus is in cooling operation, for example, as shown in  FIG. 19 , the temperature in an area B between the heat exchanger  50  and the blow-out port  3  is lowered due to cool air, thereby causing dew condensation to appear as water droplets from water vapor in the air. Therefore, in the indoor unit  100 , a water trap or the like (not shown) is attached in the vicinity of the blow-out port  3  for preventing the water droplets from coming out from the blow-out port  3 . The area where the noise detection microphone  161  and the control speaker  181  are arranged, which is on the upstream side of the heat exchanger  50  is not subjected to dew condensation, because it is located on the upstream side of the area to be cooled by cool air. 
     Subsequently, a method of restraining an operating sound of the indoor unit  100  will be described. The operating sound (noise) including the blast sound of the fan  20  in the indoor unit  100  that is detected by the noise detection microphone  161  attached between the fan  20  and the heat exchanger  50  is converted into a digital signal via the microphone amplifier  151  and the ND converter  152 , and is supplied to the FIR filter  158  and the LMS algorithm  159 . 
     A tap coefficient of the FIR filter  158  is updated sequentially by the LMS algorithm  159 . The tap coefficient is updated by the LMS algorithm  159  according to an expression 1(h(n+1)=h(n)+2μe(n)×(n)), and is updated to an optimal tap coefficient so as to cause an error signal e to approach zero. 
     In the expression shown above, h is a tap coefficient of the filter, e is the error signal, x is a filter input signal, and μ is a step size parameter, and the step size parameter μ is used for controlling the update amount of the filter coefficient at every sampling. 
     In this manner, the digital signal passed through the FIR filter  158  whose tap coefficient is updated by the LMS algorithm  159  is converted into an analogue signal by the D/A converter  154 , is amplified by the amplifier  155 , and is released into the air path in the indoor unit  100  as the control sound from the control speaker  181  attached between the fan  20  and the heat exchanger  50 . 
     And the silencing effect detection microphone  191 , attached to a lower end of the indoor unit  100  on the outer wall of the blow-out port  3  so as to avoid wind blown out from the blow-out port  3 , detects a sound which has been propagated from the fan  20  to the air path coming out from the blow-out port, the sound after having been interfered by the control sound released from the control speaker  181 . 
     Since the sound detected by the silencing effect detection microphone  191  is input to the error signal of the LMS algorithm  159  described above, the tap coefficient of the FIR filter  158  is updated so as to cause the sound after the interference to approach zero. Consequently, the noise in the vicinity of the blow-out port  3  can be restrained by the control sound having passed through the FIR filter  158 . 
     In this manner, in the indoor unit  100  to which an active silencing method is applied, the noise detection microphone  161  and the control speaker  181  are arranged between the fan  20  and the heat exchanger  50 , and the silencing effect detection microphone  191  is attached to a position avoiding the airflow from the blow-out port  3 . Therefore, since it is not necessary to attach members required for active silencing to area B which is subjected to dew condensation, water droplets dropping on the control speaker  181 , the noise detection microphone  161 , and the silencing effect detection microphone  191  is prevented, and hence deterioration of silencing capabilities or defects of the speaker or the microphone can be prevented. 
     The positions where the noise detection microphone  161 , the control speaker  181 , and the silencing effect detection microphone  191  are attached shown in Embodiment 1 are only examples. For example, as shown in  FIG. 21 , the silencing effect detection microphone  191  may be arranged between the fan  20  and the heat exchanger  50  together with the noise detection microphone  161  and the control speaker  181 . Although the microphone is exemplified as detecting means for detecting the noise or the silencing effect after having cancelled the noise using the control sound, it may be an acceleration sensor or the like for sensing vibrations of the casing. Alternatively, it is also possible to understand the sound as turbulence of air current, and detect the noise or the silencing effect after having cancelled the noise by the control sound as turbulence of the air current, In other words, a flow velocity sensor which detects the air current or a hot-wire probe may be used as the detecting means for detecting the noise or the silencing effect after having cancelled the noise using the control sound. It is also possible to detect the air current by increasing a gain of the microphone. 
     Although the FIR filter  158  and the LMS algorithm  159  are employed in the signal processing device  201  in Embodiment 1, any adaptive signal processing circuit may be employed as long as it causes the sound detected by the silencing effect detection microphone  191  to approach zero, and also may be one in which a filtered-X algorithm generally used in the active silencing method is applicable. In addition, the signal processing device  201  may be configured to generate the control signal using a fixed tap coefficient instead of employing adaptive signal processing. And further, the signal processing device  201  may be an analogue signal processing circuit instead of the digital signal processing circuit. 
     In addition, in Embodiment 1, the heat exchanger  50  disposed to cool air which forms due condensation has been described, but the invention can be applied also to a case where the heat exchanger  50  of a level which does not cause dew condensation is arranged, and has effects to prevent deterioration of performances of the noise detection microphone  161 , the control speaker  181 , the silencing effect detection microphone  191 , and the like without considering the presence or absence of occurrence of due condensation due to the heat exchanger  50 . 
     Embodiment 2 
     (Dividing Vane into Plurality of Parts) 
     When controlling the vertical wind direction control vane  70 , the horizontal wind direction control vane  80 , and the air volume of each fans  20  on the basis of the results of detection by the infrared ray sensor  410 , dividing the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  into a plurality of parts and controlling the same individually is recommended. Accordingly, comfort can further be improved. In Embodiment 2, items not specifically described are the same as those in Embodiment 1, and the same numbers reference the same functions and configurations in the description. 
       FIG. 11  is a front cross-sectional view illustrating the indoor unit according to Embodiment 2 of the invention.  FIG. 12  is a perspective view illustrating the same indoor unit.  FIG. 11  is a front cross-sectional view taken along the substantially center portions of the fans  20 . 
     In the indoor unit  100  according to Embodiment 2, the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are divided into a plurality of parts (in  FIG. 11  and  FIG. 12 , the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are each divided into two parts). 
     More specifically, the horizontal wind direction control vane  80  is divided into a horizontal wind direction control vane  80   a  arranged on the left side of the casing  1  and a horizontal wind direction control vane  80   b  arranged on the right side of the casing  1 . The horizontal wind direction control vane  80   a  is coupled to a motor  81   a , such as a stepping motor, via a link rod  82   a . The horizontal wind direction control vane  80   b  is coupled to a motor  81   b , such as a stepping motor, via a link rod  82   b . By the motor  81   a  and the motor  81   b  driven according to the number of steps commanded by the control device  281 , the orientations (angles) of the horizontal wind direction control vane  80   a  and the horizontal wind direction control vane  80   b  are changed and the direction of airflow blown from the blow-out port  3  can be controlled in the horizontal direction. The orientations (angles) of the horizontal wind direction control vane  80   a  and the horizontal wind direction control vane  80   b  can each be changed individually. 
     The vertical wind direction control vane  70  is divided into a vertical wind direction control vane  70   a  arranged on the left side of the casing  1  and a vertical wind direction control vane  70   b  arranged on the right side of the casing  1 . The vertical wind direction control vane  70   a  and the vertical wind direction control vane  70   b  are each coupled to motors (not shown) such as stepping motors. By these motors driven according to the number of steps commanded by the control device  281 , the orientations (angles) of the vertical wind direction control vane  70   a  and the vertical wind direction control vane  70   b  are changed and the direction of airflow blown from the blow-out port  3  can be controlled in the vertical direction. The orientations (angles) of the vertical wind direction control vane  70   a  and the vertical wind direction control vane  70   b  can each be changed individually. 
     In other words, the indoor unit  100  according to Embodiment 2 is capable of distributing airflows having different air volumes simultaneously to two different places in a room. Therefore, the air volumes in the two different places in the room can be controlled individually in such a manner that the air volume of the airflow to be distributed to the corresponding place may be increased if intensive distribution of the airflow is desired, and the air volume of the airflow to be distributed to the corresponding place may be decreased if avoidance of the airflow is desired. Therefore, air-conditioning in the room while maintaining the environments at two different places simultaneously is enabled. 
     For example, assume that two people are present in two separate area blocks in a room. Then, if intensive air-conditioning of these two area blocks is desired, the air volumes (that is, the rotation speed) of the fans  20  which generate the airflows reaching these two area blocks are increased. The remaining fan  20  is operated with a low air volume or is stopped. By controlling the air volumes of each fans  20  in this manner, the airflow can be distributed intensively to the area block where people are present although the air volume of the overall airflow blown out from the blow-out port  3  of the indoor unit  100  is decreased. Accordingly, the temperature environment in the area block where people are present can be further maintained, and comfortable and energy-saving operation of the indoor unit  100  can be realized. 
     Also, for example, assume that two people are present in two separate area blocks in a room, and a set temperature is reached in one of the area blocks but not in the remaining one area block. In such a case, the air volume (that is, the rotation speed) of the fan  20  which generates an airflow reaching a place where the intensive air-conditioning is desired (the area block where the set temperature is not reached) is increased. The air volume (that is, the rotation speed) of the fan  20  which generates the airflow reaching the area block in which the set temperature is reached is decreased to a low air volume. The remaining fan  20  is operated with a low air volume or is stopped. By controlling the air volumes of each fans  20  in this manner, the airflow can be distributed intensively to a place where the intensive air-conditioning is desired (the area blocks where the set temperature is not reached), and the airflow with a small air volume can be distributed also to the area block where the set temperature is reached. 
     In other words, with the indoor unit  100  according to Embodiment 2 in which the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are divided into parts, more comfortable and energy-saving operation than that of the indoor unit  100  according to Embodiment 1 can be realized. 
     Embodiment 3 
     (Dividing Vane into Number of Parts as Same as the Number of Fans) 
     By increasing the number of divisions of the vertical wind direction control vane  70  and the horizontal wind direction control vane  80 , the comfort can further be improved. Also, by employing the number of divisions of the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  as many as the number of the fans  20 , the comfort can further be improved. In Embodiment 3, items not specifically described are the same as those in Embodiment 1 and Embodiment 2, and the same numbers reference the same functions and configurations in the description. 
       FIG. 13  is a front cross-sectional view illustrating the indoor unit according to Embodiment 3 of the invention.  FIG. 14  is a perspective view illustrating the same indoor unit.  FIG. 13  is a front cross-sectional view taken along the substantially center portions of the fans  20 . The indoor unit  100  shown in  FIG. 13  and  FIG. 14  show the indoor unit  100  having three fans  20  (fans  20 A to  20 C). 
     In the indoor unit  100  according to Embodiment 3, the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are divided into parts as many as the number of the fans  20 . Since the indoor unit  100  according to Embodiment 3 includes three fans  20  (fans  20 A to  20 C), the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are each divided into three parts. 
     More specifically, the horizontal wind direction control vane  80  is divided into the horizontal wind direction control vane  80   a  arranged on the left side of the casing  1 , the horizontal wind direction control vane  80   b  arranged at the center portion of the casing  1 , and a horizontal wind direction control vane  80   c  arranged on the right side of the casing  1 . The horizontal wind direction control vane  80   a  is coupled to the motor  81   a , such as the stepping motor, via the link rod  82   a . The horizontal wind direction control vane  80   b  is coupled to the motor  81   b , such as the stepping motor, via the link rod  82   b . The horizontal wind direction control vane  80   c  is coupled to a motor  81   c , such as a stepping motor, via a link rod  82   c . By the motor  81   a  to the motor  81   c  each driven according to the number of steps commanded by the control device  281 , the orientations (angles) of the horizontal wind direction control vane  80   a  to the horizontal wind direction control vane  80   c  are changed and the direction of airflow blown from the blow-out port  3  can be controlled in the horizontal direction. The orientations (angles) of the horizontal wind direction control vane  80   a  to the horizontal wind direction control vane  80   c  can each be changed individually. 
     The vertical wind direction control vane  70  is divided into the vertical wind direction control vane  70   a  arranged on the left side of the casing  1 , the vertical wind direction control vane  70   b  arranged at the center portion of the casing  1 , and a vertical wind direction control vane  70   c  arranged on the right side of the casing  1 . The vertical wind direction control vane  70   a  to the vertical wind direction control vane  70   c  are each coupled to motors (not shown) such as stepping motors. By these motors driven according to the number of steps commanded by the control device  281 , the orientations (angles) of the vertical wind direction control vane  70   a  to the vertical wind direction control vane  70   c  are changed and the direction of airflow blown from the blow-out port  3  can be controlled in the vertical direction. The orientations (angles) of the vertical wind direction control vane  70   a  to the vertical wind direction control vane  70   c  can each be changed individually. 
     In other words, the indoor unit  100  according to Embodiment 3 is capable of distributing airflows having different air volumes simultaneously to three different places in a room. Therefore, the air volumes in the three different places in the room can be controlled individually in such a manner that the air volume of the airflow to be distributed to the corresponding place may be increased if intensive distribution of the airflows is desired, and the air volume of the airflow to be distributed to the corresponding place may be decreased if avoidance of the airflow is desired. Therefore, air-conditioning in the room while maintaining the environments at the three different places simultaneously is enabled. 
     For example, assume that three people are present in three separate area blocks in a room, and a set temperature is reached in one of the area blocks but not in the remaining two area blocks. In such a case, the air volumes (that is, the rotation speeds) of the fans  20  which generate airflows reaching places where the intensive air-conditioning is desired (the two area blocks where the set temperature is not reached) are each increased. The air volume (that is, the rotation speed) of the fan  20  which generates the airflow reaching the area block in which the set temperature is reached is decreased to a low air volume. By controlling the air volumes of each fans  20  in this manner, the airflows can be distributed intensively to places where the intensive air-conditioning is desired (the two area blocks where the set temperature is not reached), and the airflow with a small air volume can be distributed also to the area block where the set temperature is reached. Accordingly, the temperature environment of the area block where the set temperature is reached can be maintained while actively air-conditioning the places where the intensive air-conditioning are desired (the two area blocks where the set temperature is not yet reached). 
     In other words, with the indoor unit  100  according to Embodiment 3 in which the number of divisions of the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  is larger than that in Embodiment 2, further comfortable and energy-saving operation than that of the indoor unit  100  according to Embodiment 2 can be realized. 
     Also, in Embodiment 3, since the numbers of divisions of the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are set to be the same as the number of the fans  20 , the comfort can further be improved. In other words, as shown in  FIG. 13  and  FIG. 14 , the direction of the airflow generated by the fan  20 A is controlled by the vertical wind direction control vane  70   a  and the horizontal wind direction control vane  80   a . The direction of the airflow generated by the fan  20 B is controlled by the vertical wind direction control vane  70   b  and the horizontal wind direction control vane  80   b . The direction of the airflow generated by the fan  20 C is controlled by the vertical wind direction control vane  70   c  and the horizontal wind direction control vane  80   c . Therefore, the airflows controlled respectively by the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  are not the airflows generated by the plurality of fans  20 , but an airflow generated by a single fan  20 . Therefore, the air volume of the airflow to be distributed to a place where intensive control of the air volume is desired can be adjusted with high degree of accuracy, and further comfortable and energy-saving operation than the indoor unit  100  in which the numbers of divisions of the vertical wind direction control vane  70  and the horizontal wind direction control vane  80  and the number of the fans  20  are different (for example, the indoor units  100  according to Embodiment 1 and Embodiment 2) can be realized. 
     REFERENCE SIGNS LIST 
     
         
           1  casing,  1   b  back side portion,  2  suction port,  3  blow-out port,  5  bell mouth,  5   a  upper portion,  5   b  center portion,  5   c  lower portion,  6  nozzle, filter,  15  finger guard,  16  motor stay,  17  fixed member,  18  supporting member,  20  fan,  20   a  axis of rotation,  21  boss,  30  fan motor,  50  heat exchanger,  50   a  line of symmetry,  51  front side heat exchanger,  55  back side heat exchanger,  56  fin,  57  heat-transfer tube, vertical wind direction control vane,  70   a  vertical wind direction control vane,  70   b  vertical wind direction control vane,  70   c  vertical wind direction control vane,  80  horizontal wind direction control vane,  80   a  horizontal wind direction control vane,  80   b  horizontal wind direction control vane,  80   c  horizontal wind direction control vane,  81  motor,  81   a  motor,  81   b  motor,  81   c  motor, link rod,  82   a  link rod,  82   b  link rod,  82   c  link rod,  90  partitioning panel,  100  indoor unit,  110  front side drain pan,  111  drain channel,  111   a  tongue portion,  115  back side drain pan,  116  connecting port,  117  drain hose,  151  microphone amplifier,  152  ND converter,  154  D/A converter,  155  amplifier,  158  FIR filter,  159  LMS algorithm,  161  noise detection microphone,  181  control speaker,  191  silencing effect detection microphone,  201  signal processing device,  281  control device,  410  infrared ray sensor,  411  metallic container,  412  light distribution view angle,  413  housing,  414  motor,  415  mounting portion,  416  housewife,  417  infant,  418  window