Patent Publication Number: US-2010126206-A1

Title: Indoor unit for air conditioning apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This claims the priority to Korean Patent Application No. 10-2008-0117860 (filed in Korea on Nov. 26, 2008), the entirety of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     An air conditioning system is provided, and in particular an indoor unit for an air conditioning system is provided. 
     2. Background 
     In general, an air conditioning apparatus cools/heats a room using a compressor, a condenser, an expander, and an evaporator. The air conditioning apparatus may be a separated-type air conditioning apparatus in which an indoor unit is separated from an outdoor unit, or an integrated-type air conditioner in which an indoor unit is integrated with an outdoor unit. Improvements in efficiency, effectiveness and noise level during operation are desirable in either type of air conditioning apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments will be described in detail with reference to the following drawings in which like reference numerals refer to like elements, wherein: 
         FIG. 1  is a side cross-sectional view of a structure of an indoor unit for an air conditioning apparatus according to an embodiment as broadly described herein; 
         FIG. 2  is a front perspective view of a chassis of the indoor unit shown in  FIG. 1 ; 
         FIG. 3  is a partial perspective view of a fan of the indoor unit shown in  FIG. 1 ; 
         FIG. 4  is a side view of the fan shown in  FIG. 3 ; 
         FIG. 5  is a perspective view of a blade corresponding to a portion A of  FIG. 4 ; 
         FIG. 6  is a graph of a relationship between an outer circumferential angle and noise in a fan of an indoor unit according to an embodiment as broadly described herein; 
         FIG. 7  is a graph of a relationship between a ratio of inner diameter to outer diameter and noise in a fan of an indoor unit according to an embodiment as broadly described herein; 
         FIG. 8  is a graph of a relationship between a ratio of thickness to length of a fan and noise in a fan of an indoor unit according to an embodiment as broadly described herein; 
         FIG. 9  is a graph of a relationship between a ratio of an insertion depth to length of a fan and noise in a fan of an indoor unit according to an embodiment as broadly described herein; and 
         FIG. 10  is a graph of noise performance improvement of an indoor unit including a fan and an indoor unit as embodied and broadly described herein. 
     
    
    
     DETAILED DESCRIPTION 
     In a separated air conditioning apparatus, a fan and a heat exchanger that performs a heat exchange operation with indoor air drawn in by the fan may be received in the indoor unit. Air may flow from, for example, a front upper surface of the indoor unit downward to be discharged at a lower portion of the front surface of the indoor unit. A high efficiency cross flow fan may be installed in an indoor unit that is installed on a wall surface to reduce power consumption. 
     A heat exchanger that has an increased heat exchange area may also be used to improve efficiency. Such a heat exchanger may include coolant pipes arranged in 3 rows forward and backward. However, if this type of 3 row heat exchanger is used in an indoor unit in combination with a cross flow fan, system resistance may be increased. As system resistance is increased, the noise level at a given air flow rate may also be increased. For example, a surging noise may be generated. A structure in which the fan may be operated at a desired level without generating abnormal noise would be beneficial, especially when air resistance is increased due to dust accumulated on a heat exchanger or a filter after extended use, and a 3 row heat exchanger and cross flow fan are used. 
       FIG. 1  is a side cross-sectional view of an indoor unit  10  for an air conditioning apparatus, including a chassis  11  that may be closely adhered to a support surface, such as, for example, a wall, a front frame  12  that is coupled to a front side of the chassis  11 , a front panel  13  that is rotatably or slidably provided on a front surface of the front frame  12 , a fan  17  that is received in a space formed by the chassis  11  and the front frame  12  to draw indoor air into the indoor unit  10 , and a heat exchanger  16  that surrounds the fan  17  to perform a heat exchange operation with the indoor air. 
     A stabilizer  112  may be provided on a front surface of the chassis  11  to allow air flow to be generated as the fan  17  rotates. A heat exchanger seating part  111  that supports a first end of the heat exchanger  16  may be formed on an upper side of the stabilizer  112 . An inlet grill  121  may be formed on an upper surface of the front frame  12  to guide the flow of indoor air into the indoor unit  10 , and a front surface inlet port  122  may be formed on a front surface of the front frame  12 . A filter  15  may be mounted on a front surface of the heat exchanger  16  to filter indoor air drawn in through the inlet grill  121  and the front surface inlet port  122 . 
     As the indoor unit  10  operates, an upper end or a lower end of the front panel  13  may be rotated away from the front frame  12  or may be moved vertically relative to the front frame  12  to allow the front surface inlet port  122  to be opened or exposed. A discharge grill  14  may be provided on a lower end of the indoor unit  10  so that a second end of the heat exchanger  16  may be seated on an upper side of the discharge grill  14 . An air outlet port  141  may be formed on a lower side of the discharge grill  14 . A lower end of the stabilizer  112  may extend to the air outlet port  141 . A discharge louver  143  that controls a leftward and rightward flow of discharged air and a discharge vane  142  that not only selectively opens/closes the air outlet port  141  but also controls an upward and downward flow of the discharged air may each be provided on the air outlet port  141 . The discharge vane  142  and the discharge louver  143  may be rotatably coupled to each other on a lower side of the discharge grill  14 . In certain embodiments, the heat exchanger  16  may have a shape in which coolant pipes are arranged in 3 rows from front to back or are divided into plural sections so as to surround a front and an upper portion of the fan  17 , and the fan  17  may be a cross flow fan. 
       FIG. 2  is a front perspective view of the chassis shown in  FIG. 1 . In the embodiment shown in  FIG. 2 , the heat exchanger seating part  111  and the stabilizer  112  are formed on the front surface of the chassis  11 , and a fan supporter  114  is provided at a first end of the chassis  11 , along a corresponding end of the stabilizer  112 . A motor seating part  113  is provided on a side of the fan supporter  114  to support a motor that drives the fan  17 . A fan insertion groove  115  may be formed at a second end of the chassis  11  opposite the first end. The fan insertion groove  115  may have a predetermined depth t, or thickness, to support the corresponding end of the fan  17 . 
     Fan noise may be generated differently depending on the extent to which the fan insertion groove  115  extends into the chassis  11 , its thickness or depth t, and its shape. Therefore, the depth t of the fan insertion groove  115  may be one design factor to consider for reducing noise of the indoor unit  10 . Hereinafter, the relationship between the depth t of the fan insertion grove  115  and noise, and determination of an appropriate depth t of the fan insertion groove  115  will be explained. 
     Referring to  FIGS. 3 and 4 , the fan  17  included with an indoor unit  10  as embodied and broadly described herein may be a cross flow fan, and the cross flow fan may include a plurality of blades  171  that are radially arranged in a circumferential direction. Each blade  171  may be slanted at a predetermined angle θ, such that a line that extends along a width s (see  FIG. 5 ) direction of each blade is not parallel to a rotation shaft of the fan  17 , but instead is slanted by the predetermined angle θ. The fan  17  defines a mean camber line by means of an inner diameter D 1  from a center to an inner end, or root end, of the blade  171 , an outer diameter D 2  from a center to an outer end, or tip end, of the blade  171 , an inner circumferential angle β 1  and an outer circumferential angle β 2 . The mean camber line of the blade  171  (hereinafter, referred to as a camber line) is a line that bisects a thickness T of the blade  171 , essentially following the contour of the blade. 
     The inner circumferential angle β 1  is an angle defined by a line connecting the inner end, or root end, of the camber line to the center of the fan  17  and a tangential line that passes through the inner end, or root end, of the camber line at the inner diameter D 1 . Hereinafter, the inner circumferential angle β 1  will be set to approximately 90 degrees. The outer circumferential angle β 2  is an angle is defined by a straight line that extends outward from the outer end, or tip end, of the camber line and a tangential line that passes through the outer end, or tip end, of the camber line at the outer diameter D 2 . 
     Referring to  FIG. 5 , the blade  171  may have a predetermined chord length L and a predetermined width s and may be somewhat rounded in the length L direction. More specifically, an inner curvature p 1  of the blade  171  (at a surface of the blade  171  that is oriented toward the center of the fan  17 ) may be different from an outer curvature p 2  thereof (at a surface of the blade  117  that is oriented away from the center of the fan  17 ). Therefore, a thickness of the edge portion of the blade  171  may be different from that of the central portion. In other words, the blade  171  has a shape that is thick and then becomes thin from one end to the other end. And, the length L of the blade  171  is defined based on a straight line distance from the inner, root, end of the blade  171  to the outer, tip, end thereof. 
     In an indoor unit  10  in which the fan  17  constituted as described above is installed, the relationship between a ratio of inner diameter D 1  to outer diameter D 2  of the fan  17  and noise, the relationship between an outer circumferential angle β 2  and noise, the relationship between a ratio of thickness T to length L of a fan and noise, the relationship between a ratio of an insertion depth t of a side end of a fan to a length L of the fan and noise, may all be taken into consideration in reducing fan noise. 
       FIG. 6  is a graph of the relationship between an outer circumferential angle β 2  and noise in a fan in which an inner circumferential angle β 1  is set to approximately 90 degrees. As shown in  FIG. 6 , noise is on a downward trend and continues to be reduced until the outer circumferential angle β 2  of the blade  171  reaches approximately 30 degrees and then begins to increase as it exceeds 30 degrees. Thus, noise may be minimized when the outer circumferential angle β 2  is approximately 30 degrees. In certain embodiments, the outer circumferential angle β 2  of the blade  171  is preferably 28 degrees≦β 2 ≦32 degrees, and more preferably, 30 degrees≦β 2 ≈32 degrees. 
       FIG. 7  is a graph of the relationship between a ratio of inner diameter to outer diameter D 1 /D 2  and noise in a fan of an indoor unit as embodied and broadly described herein. As shown in  FIG. 7 , noise is on a downward trend and continues to be reduced until the ratio of inner diameter to outer diameter D 1 /D 2  is approximately 0.79 and then increases as the ratio of inner diameter D 1 /D 2  to outer diameter exceeds 0.79. In certain embodiments, the ratio of inner diameter to outer diameter of the blade  171  is preferably 0.77≦D 1 /D 2 ≦0.81, and more preferably, 0.77≦D 1 /D 2 ≦0.8. 
       FIG. 8  is a graph of the relationship between a ratio of thickness to length T/L of a fan blade  117  and noise in a fan of an indoor unit according to an embodiment as broadly described herein. As shown in  FIG. 8 , noise is on a downward trend and continues to be reduced until the ratio of thickness to length T/L reaches approximately 0.1, and then increases as the ratio of thickness to length T/L exceeds 0.1. In other words, the noise level is minimized at a point where the ratio of thickness to length T/L is approximately 0.1. In certain embodiments, the ratio of thickness to length of a fan is preferably 0.088≦T/L≦0.132. 
       FIG. 9  is a graph of a relationship between a ratio of an insertion depth t to length L and noise in a fan of an indoor unit according to an embodiment as broadly described herein. As shown in  FIG. 9 , noise is on a downward trend and continues to be reduced until the ratio of an insertion depth to length t/L reaches approximately 0.007, and then increases as the ratio of an insertion depth to length t/L exceeds 0.007. In other words, the noise level is minimized at a point where the ratio of an insertion depth to length is approximately 0.007. In certain embodiments, the ratio of thickness to length t/L is preferably 0.0044≦t/L≦0.0143. 
     Thus, a blowing function may be improved or maximized in a fan of an indoor unit as embodied and broadly described herein when designed based on the noise level parameters shown in  FIGS. 6 to 9 . In particular, the blowing function may be improved and the noise level may be reduced when a fan  17  and its blade  171  have a structure that takes these parameters into consideration. 
       FIG. 10  is a graph of noise performance improvement of an indoor unit including such a fan. As shown in  FIG. 10 , noise generated by a fan that does not include the improved structure as described above is represented by the lighter, grey portion of the graph, while noise generated by a fan including the improved structure as described above is represented by the black portion of the graph. A mean, or average, noise difference between these two exemplary fans, i.e., the mean or average of the noise level difference between the “before” and “after” lines at measured corresponding points is approximately 2.2. Thus, noise may be reduced by about 2.2 dB when the structure of the fan is improved as described above. This allows blowing performance of the fan to be increased and system resistance and fan noise to be reduced, and may be applied regardless of the size of the indoor unit and/or the size of the fan. 
     An indoor unit for an air conditioning apparatus as embodied and broadly described herein may include a chassis including a stabilizer that generates a flow of air, and a fan insertion groove; a cross flow fan that is mounted on a front surface of the chassis corresponding to an upper end of the stabilizer, to inhale indoor air; a heat exchanger that is provided on a front side of the fan to perform a heat exchange with the indoor air, wherein 0.088≦T/L≦0.132 (T: thickness of fan, L: length of fan). 
     In an indoor unit for an air conditioning apparatus as embodied and broadly described herein, system resistance may be reduced even when a 3 row heat exchanger is applied in order to improve heat exchange efficiency of the indoor unit. Also, although resistance due to dust accumulated on a heat exchanger or a filter is increased due to extended use, the fan may be normally operated without generating abnormal noise. Also, although a 3 row heat exchanger is used, the noise level may be reduced. 
     Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
     Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, numerous variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.