Patent Publication Number: US-2016223211-A1

Title: Air Conditioning Unit

Description:
CLAIM OF PRIORITY 
     The present application claims priority from Japanese Patent application serial No. 2015-017048, filed on Jan. 30, 2015, the content of which is hereby incorporated by reference into this application. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an air conditioning unit. 
     2. Description of Related Art 
     An air conditioning unit includes an indoor unit, an outdoor unit, and a piping for connecting the indoor unit and the outdoor unit. There are various types of indoor units including a ceiling embedded cassette type. 
     The ceiling embedded cassette type indoor unit generally includes a centrifugal fan which takes in air from a rotation axial direction and discharges the air from an outer periphery portion, and a heat exchanger with a polygonal shape for externally surrounding the centrifugal fan. 
     The above-described structure is configured that the air discharged from the centrifugal fan is obliquely directed with respect to an inner side surface or an air inflow surface of the heat exchanger, thus generating a wind noise. Generally, it has been known that the structure includes several rectifying members that protrude from the heat exchanger side toward the centrifugal fan for reducing the wind noise. 
     For example, Japanese Unexamined Patent Application Publication No. Hei 11-325497 (Patent Document 1) discloses the structure in which a rectifying member disposed around a position where a centrifugal fan is brought closest to a heat exchanger, which allows its primary side surface to block the air discharged from the centrifugal fan, and its secondary side surface with a smooth curved shape to guide the aforementioned air to the heat exchanger using Coanda effect. 
     Japanese Unexamined Patent Application Publication No. 2003-269738 (Patent Document 2) discloses an air conditioning unit configured such that any one of upper and lower ends of a rectifying plate disposed on an indoor unit body having a centrifugal fan is located at an anterior position of the other end in a fan rotating direction, and an intermediate section is inclined to a rotation axis. 
     Japanese Unexamined Patent Application Publication No. 2014-129994 (Patent Document 3) discloses an indoor unit of an air conditioning unit configured to have a slope or a stepped shaped rectifying plate so that a distance between a heat exchanger and a rectifying plate at a top panel side becomes larger than the one at a lower side. 
     SUMMARY OF THE INVENTION 
     The generally employed structure disclosed in Patent Document 1 has the rectifying plate extending toward a rotating direction. 
     The generally employed structure disclosed in Patent Document 2 discloses the rectifying plate as a planar plate perpendicular to the air inflow surface. In any of the aforementioned cases, the rectifying plate serves to block a part of the flow to reduce the wind noise. However, the aforementioned structure may generate a region behind the rectifying plate where an air flow velocity is significantly decreased, leading to a deteriorated heat exchanging performance and an increased blower power. 
     In the generally employed structure disclosed in Patent Document 3, an angle formed by the rectifying plate and the air inflow surface continuously varies in a fan rotation axial direction. However, an air flow direction exhibits a steep change in the fan rotation axial direction in accordance with a shape of a centrifugal fan blade, and a positional relationship with an air outlet. In this case, a part of the rectifying plate may have its direction largely deviated from the air flow direction. As a result, the flow separates from a surface of the rectifying plate, resulting in a lessened improvement effect. Meanwhile, the rectifying plate with the stepped shape causes a steep change in a distance between the rectifying plate and the air inflow surface around a stepped section. This may easily cause turbulence in the flow. 
     An object of the present invention provides an air conditioning unit which has an indoor unit including a centrifugal fan, the indoor unit being configured to increase a static pressure of air both at an upstream side and a downstream side of a vane of a rectifying member (a rectifying plate) so as to realize a reduction in a blower power and an improvement in a heat exchanging performance. 
     The present invention provides an air conditioning unit having an indoor unit, the indoor unit including: a casing; a centrifugal fan having a hub, a shroud, and blades disposed therebetween; and an indoor heat exchanger which surrounds the centrifugal fan, the casing containing the centrifugal fan and the indoor heat exchanger. In the indoor unit, the indoor heat exchanger has a planar air inflow surface allowing an inflow of air discharged from an air outlet of the centrifugal fan, the air inflow surface is provided with a rectifying member, the rectifying member includes a support having an insertion portion fixed between fins on the air inflow surface, and a vane having a shape extending from the support toward a direction opposite a rotating direction of the centrifugal fan, the rectifying member configured to block some of the air flowing between the centrifugal fan and the air inflow surface, and an angle formed by the insertion portion and the vane in the plane orthogonal to a rotation axis of the centrifugal fan is set to become parallel to the air inflow from the air outlet to the air inflow surface at least at the hub side to increase a static pressure of the air at upstream and downstream sides of the vane. 
     According to the present invention, in the indoor unit including the centrifugal fan for the air conditioning unit, it is possible to increase an air static pressure both at the upstream and downstream sides of the vane of the rectifying member (rectifying plate). This makes it possible to realize a reduced blower power and an improved heat exchanging performance, resulting in a highly efficient air conditioning unit. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an external perspective view of a ceiling embedded cassette type indoor unit; 
         FIG. 2  is a longitudinal section of a ceiling embedded cassette type indoor unit employed generally; 
         FIG. 3  is a transverse section of the indoor unit taken along line A-A of  FIG. 2 ; 
         FIG. 4  is a transverse section of the indoor unit taken along line B-B of  FIG. 2 ; 
         FIG. 5  is a transverse section of the indoor unit taken along line C-C of  FIG. 2 ; 
         FIG. 6  is a partial perspective view schematically illustrating a heat exchanger; 
         FIG. 7  is a side view schematically illustrating a centrifugal fan according to the present invention; 
         FIG. 8  is a longitudinal section of an indoor unit according to a first embodiment; 
         FIG. 9  is a transverse section of the indoor unit taken along line D-D of  FIG. 8 ; 
         FIG. 10  is a partial perspective view of a rectifying member according to the first embodiment; 
         FIG. 11  is a bottom view of the rectifying member according to the first embodiment; 
         FIG. 12  is a partial sectional view of a flow field around the rectifying member according to the first embodiment, taken along line E-E of  FIG. 8 ; 
         FIG. 13  is a partial perspective view of a rectifying member according to a second embodiment; 
         FIG. 14  is a partial perspective view of a rectifying member according to a third embodiment; 
         FIG. 15  is a side view of a rectifying member according to a fourth embodiment; 
         FIG. 16  is a bottom view of the rectifying member according to the fourth embodiment; 
         FIG. 17  is a side view of a modified example of the rectifying member according to the fourth embodiment; 
         FIG. 18  is a longitudinal section of an indoor unit according to a fifth embodiment; 
         FIG. 19  is a schematic block diagram of an air conditioning unit according to the present invention; 
         FIG. 20  is a perspective view of a rectifying member according to a sixth embodiment; 
         FIG. 21  is a perspective view representing a state where the rectifying member (a modified example of the sixth embodiment) according to the present invention is disposed on the indoor unit; 
         FIG. 22  is a perspective view of the modified example of the rectifying member according to the sixth embodiment; and 
         FIG. 23  is a perspective view of another modified example of the rectifying member according to the sixth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     An indoor unit according to the present invention will be described in detail referring to the drawings. 
       FIGS. 1 to 5  illustrate an example of a generally employed indoor unit  90  of a ceiling embedded cassette type to which the present invention has not been applied.  FIG. 1  is an external perspective view.  FIG. 2  is a longitudinal section of the unit including a fan rotation axis.  FIGS. 3 to 5  are transverse sections taken along lines A-A, B-B, and C-C of  FIG. 2 , respectively. 
     The drawings show a casing  1 , a panel  2 , an electrical component box  3 , a bell mouth  4 , a centrifugal fan  5 , a motor  6 , a shaft  7 , a heat exchanger (an indoor heat exchanger)  8 , a drain pan  9 , a partition  10 , a blowout port  211 , and a rotation axis  30  of the centrifugal fan  5 . Referring to the drawings, a solid arrow represents a rotating direction of the centrifugal fan  5 , and a dashed arrow represents an air flow direction. Furthermore, referring to  FIGS. 3 to 5 , each rectangle drawn by a dashed line represents a position of the blowout port  211 . 
     The casing  1  includes a side plate  101  that constitutes a side surface, a top plate  102  for covering a top surface, and a heat insulating material  103  for covering inner sides of the side plate  101  and the top plate  102 . The casing  1  is embedded in a ceiling so that a surface of the panel  2  is directed downward to a room interior. 
     A grill  201  for air intake from indoor is provided at a center of the panel  2  arranged at a bottom of the casing  1 . A filter  202  is disposed on the grill  201  for removing dust in the air. The blowout ports  211  as four thin rectangular openings are provided each at an outer periphery of the grill  201 , through which air at a temperature conditioned by the air conditioning unit  90  is fed into the room. Each of the blowout ports  211  is provided with a louver  203  for adjusting an air blowing direction. 
     Inside the casing  1 , there are provided the electric component box  3  for storing an indoor control board (not shown), the bell mouth  4  for guiding an intake air from the grill  201  to the centrifugal fan  5 , the centrifugal fan  5  for discharging the intake air from the rotation axial direction to an outer periphery portion, the motor  6  for driving the centrifugal fan  5 , the shaft  7  for connecting the centrifugal fan  5  and the motor  6 , the heat exchanger  8  for exchanging heat between the air discharged from the centrifugal fan  5  and the refrigerant, and the drain pan  9  disposed below the heat exchanger  8  for receiving dew condensation water generated in the heat exchanger  8  during a cooling operation. 
     The heat exchanger  8  of cross fin tube type as illustrated in  FIG. 6 , for example, includes a plurality of U-shape heat transfer pipes  801  which are arranged in parallel with one another, a large number of thin plate fins  802  arranged at substantially uniform intervals along the axial direction of the heat transfer pipe  801 , and a plurality of return bends  803  for connecting the heat transfer pipes  801  with one another. The heat transfer pipes  801  that pierce through the fins  802  are expanded so as to be brought into close contact with the fins  802 . This makes it possible to exchange heat between the refrigerant flowing through the heat transfer pipes  801  and air flowing through the gap between the fins  802  via the wall surfaces of the heat transfer pipes  801  and the fins  802 . 
     Referring to  FIG. 3 , the heat exchanger  8  of the indoor unit  90  is bent into substantially a pentagonal shape to surround the centrifugal fan  5 . Both ends of the heat exchanger  8  are connected with the partition  10 . A machine chamber  20  for storing an expansion valve (not shown) and the like is defined by the partition  10  and the casing  1 . 
       FIG. 7  represents an example of the centrifugal fan  5  including a hub  501 , a shroud  502  opposite the hub  501  in the fan rotation axial direction, and blades  503  which are arranged at uniform intervals between the hub  501  and the shroud  502  in the circumferential direction. 
     The hub  501  has a boss (not shown) at a center for fixing the centrifugal fan  5  to the shaft  7 . Meanwhile, the shroud  502  has a circular opening, that is, an air inlet  521  at a center for air intake from the fan rotation axial direction. 
     The blade  503  is twisted (S-shape), and inclined in a direction opposite the fan rotating direction. A blade rear edge  511  (a rear edge of the blade  503 ) seen from an outer peripheral side has an inflection point at which the shape changes from convex to concave along the fan rotation axial direction. Referring to the drawing, a height of the inflection point of the blade rear edge is indicated by a line p-p. An air outlet  522  for discharging the air is formed at the outer periphery portion between the two adjacent blades  503 . 
     The air flow will be described using dashed arrows. 
     Upon rotation of the centrifugal fan  5  driven by the motor  6 , the indoor air is taken into the indoor unit  90  through the grille  201  as shown in  FIG. 2 , and is drawn into the centrifugal fan  5  after passing through the filter  202  and the bell mouth  4 . The air boosted by the centrifugal fan  5  is discharged from the outer periphery portion of the centrifugal fan  5 , and flows into the heat exchanger  8 . The heat exchanger  8  is configured to exchange heat between the air flowing through the fins  802  and the refrigerant flowing in the heat transfer pipes  801  for heating or cooling operation. The air is then fed indoor from the blowout port  211  after passing through the section defined by the casing  1  and the drain pan  9 . 
       FIGS. 3 to 5  are transverse sections perpendicular to the fan rotation axis, each showing the air flow from the centrifugal fan  5  to the heat exchanger  8 . The respective sections represent the phases between the hub of the centrifugal fan  5  and the inflection point of the blade rear edge (corresponding to  FIG. 3 ), between the inflection point of the blade rear edge and the shroud of the centrifugal fan  5  (corresponding to  FIG. 4 ), and below the shroud (corresponding to  FIG. 5 ). 
     In either case, the air flow direction is inclined with respect to the fin of the heat exchanger  8  toward the fan rotating direction. This phenomenon will be frequently observed at an anterior position of a point at which the centrifugal fan  5  is brought closest to the heat exchanger  8  in the fan rotating direction. The planar air inflow surfaces  8   b ,  8   d ,  8   f ,  8   h  of the heat exchanger are likely to generate a turbulence between the fins compared with surfaces  8   a ,  8   c ,  8   e ,  8   g . This may interfere with air inflow, resulting in small amount of passing air. As a result, the flow velocity distribution becomes uneven in a circumferential direction of the heat exchanger  8  to increase the air flow loss and the blower power, resulting in a deteriorated heat exchanging performance. 
     The air flow direction influenced by the blade shape of the centrifugal fan  5  significantly changes at the position near the height of the inflection point of the blade rear edge. Specifically, the air flow direction indicated by the longitudinal section including the fan rotation axis becomes substantially horizontal above the inflection point indicated by the line p-p as shown in  FIG. 2 . Meanwhile, it is directed obliquely downward in the region below the inflection point. As clearly shown in the transverse section perpendicular to the fan rotation axis, that is,  FIGS. 3 and 4 , the velocity component parallel to the air inflow surface of the heat exchanger  8  becomes large when it is below the inflection point. This may increase an inclination angle α with respect to the fin as shown in  FIG. 3 . 
     The air flow direction slightly changes as well between the hub of the centrifugal fan  5  and the inflection point of the blade rear edge, or between the inflection point of the blade rear edge and the shroud of the centrifugal fan  5 . Such change, however, is far smaller than the change which occurs around the inflection point of the blade rear edge. 
     The air flow direction largely changes around a height position where the shroud is disposed depending on a positional relationship with the centrifugal fan  5 . In the area below the shroud, the direction is strongly influenced by a swirl generated between the shroud and the bell mouth  4 . The resultant inclination angle with respect to the fin is further increased as shown in  FIG. 5  so that the air flow direction becomes substantially parallel to the air inflow surface therearound. 
     As described above, the air flow direction largely changes around the height of the inflection point of the blade rear edge, and the height of the shroud. As a result, the flow velocity distribution in the fan rotation axial direction is uneven, causing increase in the blower power and deterioration in the heat exchanging performance. 
     In the present invention, the rectifying member is formed into the shape adaptable to change in the air flow direction for the purpose of reducing the blower power and improving the heat exchanging performance. Preferred embodiments of the present invention will be described in detail hereinafter referring to the drawings. 
     First Embodiment 
     A first embodiment of the present invention will be described referring to  FIGS. 8 to 11 .  FIG. 8  is a longitudinal section of an indoor unit  91  including the fan rotation axis.  FIG. 9  is a transverse section of the indoor unit  91  taken along line D-D of  FIG. 8 .  FIG. 10  is an enlarged perspective view of a rectifying member  920 .  FIG. 11  is a bottom view of the rectifying member  920  seen from a direction indicated by arrow Z of  FIG. 10 . In the drawings, the lines s-s, p-p, q-q, and t-t indicate a position of the hub of the centrifugal fan  5 , the inflection point position at which the blade rear edge changes its shape from convex to concave, an upper end position of the shroud, and a lower end position of the shroud, respectively. Numeral  811  denotes an air inflow surface of the heat exchanger  8 . 
     The rectifying member  920  includes a thin plate support  931 , a thin plate vane  932  which extends from one end of the support  931  toward a direction opposite a fan rotating direction and is inclined at an angle θ 2  with respect to the support  931 , a thin plate vane  934  which extends from one end of the support  931  toward the direction opposite the fan rotating direction and is inclined at an angle θ 4  with respect to the support  931 , a vane  933  which extends from one end of the support  931  for connecting the vanes  932  and  934 , a rib  935  disposed between inner surfaces of the support  931  and the vane  932 , and a rib  936  disposed between inner surfaces of the support  931  and the vane  934 . 
     The support  931  is made thinner than the gap between the fins, which is inserted therethrough from the air inflow surface  811 , and fixed to the heat exchanger  8  by fitting with the heat transfer pipe or by bonding to the fin. A part of the support  931  protrudes from the air inflow surface  811  to the centrifugal fan  5 , serving to block the inflow air between the vanes  932 ,  933 ,  934  and the air inflow surface  811 . The longitudinal dimension L 1  along the fan rotation axial direction is smaller than the height of the centrifugal fan  5 , that is, the distance between the lines s-s and t-t. 
     The space between the vane  932  and the air inflow surface  811  is gradually narrowed toward the support  931 . The end of the vane  932  at the fan side is apart from the air inflow surface  811  by the distance H 2 . The longitudinal dimension L 2  of the vane  932  along the fan rotation axial direction is slightly smaller than the height defined by the hub of the centrifugal fan  5  and the inflection point of the blade rear edge, that is, the distance between the lines s-s and p-p. 
     A space between the vane  934  and the air inflow surface  811  is gradually narrowed toward the support  931 . The end of the vane  934  at the fan side is apart from the air inflow surface  811  by the distance H 4 . The vane  934  is disposed between the height of the inflection point of the blade rear edge indicated by the line p-p and the lower end of the shroud indicated by the line t-t. Therefore, the longitudinal dimension L 4  of the vane  934  along the fan rotation axial direction is smaller than the distance between the lines p-p and t-t. 
     The vane  933  is disposed between the lower end of the vane  932  and the upper end of the vane  934  at the angle with respect to the support  931  gradually reduced from θ 2  to θ 4 . 
     The rib  935  is disposed between the inner surfaces of the support  931  and the vane  932  to secure the angle θ 2 . 
     The rib  936  is disposed between the inner surfaces of the support  931  and the vane  934  to secure the angle θ 4 . 
     Referring to  FIG. 9 , each one of the rectifying members  920   a ,  920   b ,  920   c  and  920   d  is disposed on the corresponding one of the planar air inflow surfaces  8   b ,  8   d ,  8   f  and  8   h  of the heat exchanger, which is apart from the position where the centrifugal fan  5  is brought closest to the heat exchanger  8  by a predetermined distance, respectively. As  FIG. 8  shows, the support  931  is substantially in parallel with the fan rotation axial direction, having the upper end substantially as high as the hub of the centrifugal fan  5 . The lower end of the vane  932  is above the height of the inflection point of the blade rear edge indicated by the line p-p, and the upper end of the vane  934  is below the height of the inflection point of the blade rear edge. The lower end of the vane  934  is positioned between the upper end of the shroud indicated by the line q-q and the lower end of the shroud indicated by the line t-t. 
     Operations of the rectifying member  920  will be described hereinafter. 
       FIG. 12  represents a flow field around the rectifying member  920  on the partial sectional view taken along line E-E of  FIG. 8 . The air discharged from the centrifugal fan  5  is divided into two flows, that is, a flow F 1  passing along the path defined by the vane  932  and the air flow surface  811  of the heat exchanger  8 , and a flow F 2  passing over the vane  932  to the rear of the rectifying member  920 . 
     The flow F 1  is decelerated under the influence of the vane  932  while changing the flowing direction, and blocked by the support  931 . Therefore, kinetic energy of the flow F 1  is partially converted into static pressure, which increases the static pressure difference between the air outflow surface (not shown) and a part of the air inflow surface  811  of the heat exchanger  8  disposed on an upstream side of a position where the support  931  is disposed, thus increasing amount of air passing through the heat exchanger  8 . In addition, the air flow direction is changed by the vane  932  to reduce the inclination angle α with respect to the fin, which suppresses the turbulence generated among the fins, thus lessening the flow loss. 
     Unlike the case where the rectifying member  920  is not disposed, the air flow velocity around the air flow surface  811  is retarded in a region disposed on a downstream side of a position where the support  931  is disposed. The resultant static pressure becomes high, promoting the air inflow to the heat exchanger. 
     Each amount of air passing through the air inflow surfaces  8   a ,  8   c ,  8   e ,  8   g  of the heat exchanger will be decreased as increase in each amount of air passing through the air inflow surfaces  8   b ,  8   d ,  8   f ,  8   h . The flow velocity distribution in the circumferential direction of the heat exchanger is then improved, which makes it possible to reduce the blower power and improve the heat exchanging performance. 
     The present invention has characteristics as described below so as to maximize the effect derived from the rectifying member  920 . 
     (1) The rectifying member  920  has the angle θ 2  formed by the vane  932  and the support  931  larger than the angle θ 4  formed by the vane  934  and the support  931 . 
     Upon separation of the air flow from the vane surface, turbulence occurs in the flow, generating the region at significantly low flow velocity behind the rectifying member. Such region may cause increase in the blower power and deterioration in the heat exchanging performance. Therefore, it is necessary to coincide the vane direction with the air flow direction in order to cope with the aforementioned problems. 
     Meanwhile, the air flow direction under strong influence of the vane shape of the centrifugal fan  5  is remarkably changed around the inflection point of the blade rear edge. The inclination angle of the flow with respect to the fin in the region below the inflection point of the blade rear edge is larger than the one in the region above the inflection point. Accordingly, the angle formed by the vane and the support is varied at the position around the height of the inflection point of the blade rear edge so as to coincide the vane direction with the air flow direction. 
     (2) The vane  933  disposed between the vanes  932  and  934  gradually changes the angle formed with the support  931  from θ 2  to θ 4 . 
     Steep change in the angle formed by the vane and the support will generate the stepped portion on the vane surface, around which turbulence is likely to occur. The vane  933  allows smooth surface of the vane, serving to induce the air with velocity component in the fan rotation axial direction. This makes it possible to suppress generation of the turbulence. 
     (3) The lower end of the vane  934  is above the lower end of the shroud of the centrifugal fan  5 . 
     In the region below the shroud, the velocity component parallel to the air inflow surface of the heat exchanger is significantly intensified as  FIG. 5  shows, and the advancing direction of the air flowing around the air inflow surface is substantially in parallel therewith. As the direction of the vane  934  disposed in the aforementioned region is greatly different from the air flow direction, the flow will separate from the vane surface, resulting in adverse effects. 
     (4) The ribs  935  and  936  are provided to secure angles θ 2  and θ 4 , which are formed by the vane  932  and the support  931 , and by the vane  934  and the support  931 , respectively. 
     Generally, resin is used for forming the rectifying member  920  with small thickness, which may cause the risk of easy deformation during a fitting work etc. Provision of the rib enhances strength of the rectifying member  920  so as to secure the angle formed by the vane and the support. 
     (5) The rectifying member  920  is disposed at an anterior position (a downstream side) of the position at which the centrifugal fan  5  is brought closest to the heat exchanger  8  in the fan rotating direction so that a fitted position of the support  931  satisfies the relationship of 0.2 G&lt;W&lt;0.5 G. Reference letter W denotes a distance between the insertion portion of the support  931  and the position at which the distance between the centrifugal fan  5  and the heat exchanger  8  (indoor heat exchanger) becomes the shortest on the air inflow surface  811 . Reference letter G denotes a distance between the end of the air inflow surface  811  at an anterior position of the position at which the distance between the centrifugal fan  5  and the heat exchanger  8  (indoor heat exchanger) becomes the shortest in the rotating direction of the centrifugal fan  5 , and the position at which the distance becomes the shortest (a horizontal direction of the air inflow surface  811 ). The angle θ 2  formed by the vane  932  and the support  931  is equal to or smaller than 135°, and the angle θ 4  formed by the vane  934  and the support  931  is equal to or smaller than 115°. 
     Provision of the support  931  around the position at which the static pressure on the air inflow surface is the lowest will provide higher effect of improving the rectifying member  920 . According to results of the analysis carried out in the present invention, the static pressure distribution on the air inflow surface is influenced by various factors. The static pressure is the lowest in the region at an anterior position of the position at which the centrifugal fan  5  is brought closest to the heat exchanger  8  in the fan rotating direction by the distance ranging from 0.2 G to 0.5 G. 
     The inclination angle α of the flow with respect to the fin is equal to or larger than 45° in the region above the inflection point of the blade rear edge, and in the region therebelow, is equal to or larger than 65°. The vane may be directed to be coincided with the air flow by setting the angle θ 2  formed by the vane  932  and the support  931  to be equal to or smaller than 135°, and the angle θ 4  formed by the vane  934  and the support  931  to be equal to or smaller than 115°. 
     In this embodiment, each of the planar air inflow surfaces  8   b ,  8   d ,  8   f ,  8   h  of the heat exchanger is provided with a single rectifying member. It is possible to adjust the number of rectifying members in consideration of improvement effects, manufacturing costs and the like. Each shape of the rectifying members, and the fitted position of the support do not have to be the same, which may be set separately. The gaps H 2  and H 4  between the fan side end of the vane and the air inflow surface may be equally set. However, they may be made different so that the improvement effect of the rectifying member is maximized. 
     Second Embodiment 
     In this embodiment, the same components as those described in the first embodiment will be designated with the same numerals, and explanations thereof, thus will be omitted so that the difference from the first embodiment will be explained mainly hereinafter. 
       FIG. 13  represents the second embodiment according to the present invention. The support  931  of a rectifying member  921  has rectangular openings  941 ,  942  through which the inflow air between the vane and the air inflow surface  811  of the heat exchanger partially flows to the rear of the support  931 . Therefore, even if the vane direction is deviated from the given direction owing to a fitting error, it is possible to suppress the region where the flow velocity is significantly lowered. Adjustment of the number of openings, size and position thereof allows control of the static pressure improvement effect in the fan rotation axial direction. 
     Third Embodiment 
       FIG. 14  represents a third embodiment according to the present invention. This embodiment is different from the first embodiment in that the support  931  has an extended thin plate section  951  at the lower end. Some of the flowing air around the air inflow surface  811  is blocked in the region below the centrifugal fan  5  so that the amount of air passing through the part of the heat exchanger at an anterior position of a fitted position of the thin plate section  951  increases together with the static pressure. Meanwhile, the part of the thin plate section  951  protruding from the air inflow surface  811  is very low in height. This makes it possible to suppress reduction in the flow velocity behind the part. As a result, the improvement effect of the rectifying member may further be enhanced. 
     Fourth Embodiment 
       FIGS. 15 and 16  represent a fourth embodiment according to the present invention.  FIG. 15  is a side view of a rectifying member  923  seen from the fan side, and  FIG. 16  is a bottom view of the rectifying member  923  seen from the direction indicated by arrow Y of  FIG. 15 . The air inflow surface  811  of the heat exchanger  8  is shown in  FIG. 16 . Referring to  FIG. 15 , the line s-s denotes the position of the hub of the centrifugal fan  5 , the line p-p denotes the inflection point at which the blade rear edge varies its shape from convex to concave, the line q-q denotes the upper end of the shroud, and the line t-t denotes the lower end of the shroud. The solid arrow of the drawing denotes the rotating direction of the centrifugal fan  5 . 
     The rectifying member  923  includes thin plate supports  961 ,  963 ,  965  protruding from the air inflow surface  811  toward the centrifugal fan  5 , a thin plate vane  962  extending from one end of the support  961  in the direction opposite the fan rotating direction while inclining at the angle θ 4  with respect to the support  961 , a thin plate vane  966  extending from one end of the support  965  in the direction opposite the fan rotating direction while inclining at the angle θ 2  with respect to the support  965 , a vane  964  extending from one end of the support  963  to connect the vanes  962  and  966 , a rib  967  disposed between inner surfaces of the support  961  and the vane  962 , and a rib  968  disposed between inner surfaces of the support  965  and the vane  966 . 
     The embodiment is different from the first embodiment primarily in that the support  965  of the rectifying member  923  is substantially in parallel with the support  961 , and located forward in the fan rotating direction. The support  963  is inclined with respect to the supports  961  and  965  while connecting the lower end of the support  961  to the upper end of the support  965 . 
     In the indoor unit, the air flow direction steeply changes around the height of the inflection point of the blade rear edge, which makes the inclination angle of the flow larger with respect to the fin in a lower region. Accordingly, the static pressure distribution on the air inflow surface  811  changes around the height of the inflection point of the blade rear edge so that the distance between the location at the lowest static pressure and the position where the centrifugal fan  5  becomes closest to the heat exchanger  8  is shorter in the lower region. On the other hand, as the improvement effect derived from the rectifying member depends on the fitted position of the support, the higher improvement effect may be obtained by using the rectifying member  923  which allows the support to be fitted on the point at the lowest static pressure in the fan rotation axial direction. 
     A modified example of the embodiment is configured by separately producing a rectifying member  924  to be disposed in the region above the inflection point of the blade rear edge, and a rectifying member  925  to be disposed in the region below the inflection point, and fitting those rectifying members, as shown in  FIG. 17 . Since those two respective rectifying members  924 ,  925  do not have complicated configurations, they may be easily produced. Each support does not have a complicated shape so as to allow easy provision of the rectifying members  924 ,  925 . 
     Fifth Embodiment 
       FIG. 18  is a longitudinal section representing a fifth embodiment according to the present invention. This embodiment is different from the first embodiment primarily in the upper end position of the vane. In other words, the upper end of the vane of the rectifying member  926  is positioned at the level lower than the hub of the centrifugal fan  5 . 
     In the indoor unit  92 , a heat insulating material  97  at the top panel side is provided with a protruding portion  99  (a thick part of the heat insulating material). A vortex will be generated in a space n formed between an outer surface of the protruding portion  99  and the air inflow surface of the heat exchanger  8 . In this case, like the first embodiment, if the upper end of the vane is positioned at the same level as the hub, the vortex will be interfered with the separated flow generated at the upper end of the vane, thus interrupting the flow into the part of the heat exchanger, which faces the space n. This may increase the blower power and deteriorate the heat exchanging performance. In order to avoid the aforementioned disadvantages, the upper end of the vane is positioned apart from the space n by a predetermined distance. 
     Sixth Embodiment 
       FIG. 20  is a perspective view representing the rectifying member of a sixth embodiment according to the present invention. 
     A rectifying member  351  shown in the drawing is configured simpler than the one described in the first to the fifth embodiments. 
     The rectifying member  351  includes a vane  352  corresponding to the blowout port of the fan, and a vane  353  corresponding to the fan shroud. The rectifying member  351  includes a support  391 , insertion portions  356 ,  357 , and grips  354 ,  355 . The support  391  is curved so that direction of the vane  352  is adapted to the inclination angle α of the flow with respect to the fin. The insertion portions  356 ,  357  are inserted between the fins, and fixed. The grips  354 ,  355  are configured to be gripped by the operator to assist in easy provision of the rectifying member  351 . As the drawing shows, the grip  354  has a plate-like shape easy to hold, and the grip  355  has a bar-like shape. 
     A top end  358  of the support  391  is configured to be fit with a recessed portion formed in the heat insulating material of the casing for the indoor unit. 
     The vane  352  is configured to be adapted to the inclination angle α of the flow with respect to the fin for the purpose of corresponding to the fan blowout port at high air flow velocity. The vane  353  located in the region at relatively lower air flow velocity which is small in width allows loose limitation of the angle. It is therefore possible to be configured adaptable to the inclination angle α like the vane  352 . 
       FIG. 21  is a perspective view representing that the rectifying member according to the present invention is disposed in the indoor unit. This drawing represents the inner side of the heat exchanger  8  seen from below. 
     A rectifying member  371  is slightly different in its shape from the rectifying member  351  as shown in  FIG. 20 , but substantially the same in terms of the function. Configurations of grips  372 ,  373  are different from those shown in  FIG. 20 . 
     The top end  358  of the rectifying member  371  will be fitted with a recessed portion  361  formed in the heat insulating material  103  of the casing for the indoor unit. 
       FIG. 22  is an enlarged view of the rectifying member  371  shown in  FIG. 21 . 
     The rectifying member  371  has the vanes  352 ,  353 ,  393  fixed to the support  391 . 
     The vane  352  may be described in the similar way to the one referring to  FIG. 20  as described above, which corresponds to the region at the higher air flow velocity. 
     Each of sections I to IV surrounded by dashed lines will be described referring to the drawings. 
     The section I is positioned above the fan blowout port in the region near the heat insulating material as the inner wall of the casing for the indoor unit. In this section, the air flow velocity is decreased. Therefore, the vane  393  is configured to reduce its width toward the top portion. 
     The section II is positioned in the region at the relatively low air flow velocity, and configured to reduce its width downward. 
     The section III serves to reduce the vane width because of the need to prevent air flow parallel to the air inflow surface of the heat exchanger from hindering the air inflow to the heat exchanger at a downstream side of the vane. 
     In the section IV corresponding to the fan shroud, the air flow velocity is low. There is less necessity to increase width of the vane  353 , and accordingly, the vane width is made small. 
       FIG. 23  is a perspective view of another modified example of the rectifying member. 
     A rectifying member  381  has vanes  382 ,  383 ,  384  fixed to the support  391 . 
     The vane  382  may be described in the similar way to the one referring to  FIG. 20  as described above, which corresponds to the region at the higher air flow velocity. 
     The section I shown in the drawing has the width of the vane at the upper part of the rectifying member  381  kept small uniformly rather than gradually reducing the width. 
     Referring to the section II, the vane  383  has its width steeply reduced downward, and the vane  384  has the width uniformly kept small. 
     The section III has a long part with the vane width kept uniformly smaller compared with the section shown in  FIG. 22 . 
     The section IV has a part with the vane width kept uniformly smaller, which is not provided in the member shown in  FIG. 22 . 
     The cross fin tube type heat exchanger has been described in the first to the sixth embodiments. However, the heat exchanger of any other type, for example, parallel flow type heat exchanger is also applicable. Any type of the indoor unit is available so long as the air flow is inclined with respect to the air inflow surface of the heat exchanger without being limited to the indoor unit of ceiling embedded cassette type. 
     The structure and operation of the air conditioning unit will be described below. 
       FIG. 19  is a schematic diagram representing structure of the air conditioning unit according to the present invention. 
     Referring to the drawing, an air conditioning unit  300  includes a compressor  302  for compressing the refrigerant, an indoor heat exchanger  303 , an expansion valve  304 , an outdoor heat exchanger  305 , and a four-way valve  306 , which are connected via refrigerant pipings  311 ,  312 ,  313 ,  314 ,  315 ,  316 . The air conditioning operation may be selected from cooling and heating by switching the four-way valve  306 . 
     In the cooling operation, the refrigerant discharged from the compressor  302  passes through the refrigerant piping  311 , the four-way valve  306 , and the refrigerant piping  312  as indicated by solid arrow so as to release heat to outdoor air by the outdoor heat exchanger  305 . Then, it further passes through the refrigerant piping  313 , the expansion valve  304  and the refrigerant piping  314  so as to absorb heat from indoor air by the indoor heat exchanger  303 . The refrigerant passes through the refrigerant piping  315 , the four-way valve  306 , and the refrigerant piping  316 , and returns to the compressor  302 . 
     Meanwhile, in the heating operation, the refrigerant discharged from the compressor  302  passes through the refrigerant piping  311 , the four-way valve  306 , and the refrigerant piping  315  as indicated by dashed arrow so as to release heat to indoor air by the indoor heat exchanger  303 . It further passes through the refrigerant piping  314 , the expansion valve  304  and the refrigerant piping  313  so as to absorb heat from outdoor air by the outdoor heat exchanger  305 . The refrigerant passes through the refrigerant piping  312 , the four-way valve  306 , and the refrigerant piping  316 , and returns to the compressor  302 . 
     The specification explains the air conditioning unit using the heat pump function as a result of compression and expansion of the refrigerant as described referring to  FIG. 19 . However, the present invention is not limited to the aforementioned description. It is also applicable to the indoor cooling and heating operation by supplying cold or hot water to the indoor heat exchanger.