Patent Publication Number: US-6032479-A

Title: Fan duct for a window-mounted air conditioner

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a window-mounted type air conditioner, and more particularly, to an air-circulation fan arrangement of such an air conditioner. 
     2. Prior Art 
     A window-mounted type air conditioner has an outdoor heat exchanger (called a condenser) which is installed at the outer side of a window and used in condensing a compressed refrigerant, and an indoor heat exchanger (called an evaporator) which is installed at the inner side of the window and used in evaporating a refrigerant condensed in the outdoor heat exchanger so as to absorb heat of ambient room air. 
     The appearance of the body of such a window-mounted type air conditioner is formed by a front cover, rear cabinet, and a base. 
     The front cover has a suction grill through which room air is drawn into the air conditioner, and a discharge grill for discharging cool air. 
     The indoor heat exchanger and the outdoor heat exchanger are disposed on a base and are spaced from each other at a predetermined distance. Between the indoor heat exchanger and the outdoor heat exchanger is disposed a duct having a passage for air flow. The duct 60 has, as shown in FIG. 1, guides 61a and 62a for forming a scroll type air passage. The reference numeral 71 shown in the figures is a cross-flow fan (hereinbelow, referred to as a `first fan`). The first fan 71 is assembled to a shaft 70a of a fan motor disposed on an appropriate position in the duct 60. As the first fan 71 rotates, outside air which is in the room is drawn into the first fan 71 along the axis thereof, and then discharged along the outer circumference thereof. The discharged air is guided by the air passage of the duct 60 so as to be discharged into the room through the discharge grill of the front cover. In such a situation, the discharged air is cool air which has been cooled while it passes through the indoor heat exchanger. 
     Meanwhile, at the opposite side of the fan motor is installed a second fan facing the outdoor heat exchanger. Furthermore, on a side of the base, a compressor is mounted for compressing the refrigerant into a refrigerant of high temperature and pressure. 
     The refrigerant which has passed through the indoor heat exchanger is compressed by the compressor to a high temperature and pressure, and the compressed refrigerant exchanges heat with the ambient air of room temperature in the outdoor heat exchanger. The liquid refrigerant of room temperature and high pressure which has undergone such a heat exchange process is reduced in pressure by a capillary tube, and then flows into the indoor heat exchanger. 
     Meanwhile, the air in the room which is drawn through the suction grill by the first fan 71 flows into the indoor heat exchanger. The drawn air is cooled while it passes through the indoor heat exchanger. The cooled air flows along the air passage of the duct 60 by the first fan 71 and then is discharged into the room thereby through the discharge grill. 
     However, in the general window-mounted type air conditioner having such a construction, the sectional area A1 of a part 60a of the air passage formed by the duct 60 is broad, while the sectional area A2 of another part 60b of the air passage (located upstream of the part 60a) formed by the duct 60 is narrow. 
     Therefore, when the first fan 71 rotates to draw and discharge the outside air, a lot of air traverses the broad air passage, but a small amount of air traverses the narrow air passage since the pressure of air therein is low. Even worse, some of the air being discharged from the area A1 reenters the narrow air passage as shown at R in FIG. 2. This is because the velocity of the air flowing through the passage having broad sectional area A1 is low, while the velocity of the air flowing through the passage having narrow sectional area A2 is relatively high. Thus, a part of the slow air is inhaled into the passage of the fast air. 
     Such an inverse flow of the air causes a noises, a lowering of the cooling capacity versus size, and increase of the power consumption, so an improvement thereon is desired. 
     SUMMARY OF THE INVENTION 
     The present invention has been proposed to overcome the above described problems in the prior art, and accordingly it is an object of the present invention to provide a window-mounted type air conditioner having improved structure of the air passage so as to be capable of preventing a backflow of air and discharging the cool air with a uniform velocity across the overall area of the discharge grill. 
     To achieve the above object, the present invention provides an window-mounted type air conditioner comprising: a body comprising a front cover, a rear cabinet, and a base. The front cover includes an air discharge grill. An indoor heat exchanger is disposed on a front portion of the base, and an outdoor heat exchanger is disposed on a rear portion of the base. A compressor is installed on the base, and a fan motor is disposed between the indoor heat exchanger and the outdoor heat exchanger. The fan motor is connected to a first fan located adjacent the indoor heat exchanger, and a second fan located adjacent to the outdoor heat exchanger. A duct is disposed between the first fan and the indoor heat exchanger. The duct forms an air passage extending around an outer periphery of the first fan for guiding air drawn-in by the first fan toward the discharge grill. One part of the passage has a larger cross-sectional area than another part of the passage located upstream of the one part. A restriction is disposed in the one part for increasing velocity and reducing pressure of air passing through the one part, thereby making the velocity and pressure of air flowing through the one part substantially the same as the velocity and pressure of air flowing through the second part. 
     Preferably, the restriction comprises at least one guide blade installed in the one part of the passage for dividing the one part into smaller sections. Preferably, the guide blade is disposed substantially on a line coinciding with a radius of the first fan. 
     In such a window-mounted type air conditioner, the air drawn by the first fan is cooled while it flows through the indoor heat exchanger, and then is discharged into the room through the air passage and the discharge grill. The air is discharged with uniform pressure and velocity by the guide blade installed in the air passage, so the velocity of the discharged air becomes uniform across the overall area of the discharge grill. Therefore, the cool air can be stably discharged and a back-flow of the cool air can be prevented. Furthermore, since back-flow of the cool air is prevented, noise is reduced and the power consumption can be reduced in comparison with the cooling capacity. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be better understood and its various objects and advantages will be more fully appreciated from the following description taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a front view of a fan duct of a prior art window-mounted type air conditioner; 
     FIG. 2 is a view similar to FIG. 1 showing the flow of air in the duct; 
     FIG. 3 is an exploded top perspective view of a window-mounted type air conditioner according to a preferred embodiment of the present invention; 
     FIG. 4 is a front view of a fan duct of the window-mounted type air conditioner shown in FIG. 3, and 
     FIG. 5 is a view similar to FIG. 4 showing the flow of air in the duct. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings. 
     FIG. 3 is an enlarged perspective view of a window-mounted type air conditioner according to a preferred embodiment of the present invention. In the description of the present embodiment, the same parts with the parts of the conventional air conditioner shown in FIGS. 1 and 2 will be referred to with the same reference numerals. 
     As shown, the appearance of the body 1 of such a window-mounted type air conditioner is formed by a front cover 10, a rear cabinet 20, and a base 30. 
     The front cover 10 has a front suction grill 12 through which room air is drawn into the air conditioner and a top discharge grill 11 for discharging cool air toward the room is formed at the upper part of the front cover 10. 
     The indoor heat exchanger 40 and the outdoor heat exchanger 50 are disposed on the base 30 while spaced from each other at a predetermined distance. The heat exchangers 40 and 50 are connected with each other through a capillary tube 51. Between the indoor heat exchanger 40 and the outdoor heat exchanger 50 is disposed a duct 60 having a generally annularly extending passage for air flow. The duct 60 is comprised of two plates 61 and 62. The plates 61 and 62 have guides 61a and 62a respectively, which are formed together therewith. The upper part of the air passage communicates with the discharge grill 11 of the front cover 10. Therefore, the air which has been cooled while it passes through the indoor heat exchanger 40 is discharged into the room through the discharge grill 11. 
     On the plate 62 of the duct 60, a restriction in the form of at least one guide blade 63 is installed. The guide blade 63 divides the part 60a of the air passage which is broader than the other part 60b of the passage into two separate sections 160a and 160a&#39; having the same sectional areas A1 and A&#39;1 as one another so that the velocities of the air flowing therethrough are equal and increased as compared with FIG. 1. The velocity and the pressure of the air flowing through the parts 60a, 60b are made substantially uniform by the guide blade 63. Therefore, no reentry of air into an upstream end P&#39; of the passage and thus into the other air passage part 60b having narrow sectional area occurs (as occurs at R in the prior art depicted in FIG. 2), and thereby the velocity of the discharged air becomes uniform across the overall area of the discharge grill 11. 
     In such a situation, the guide blade 63 is disposed on a line extending generally radially from the axis of the first fan 71, and one or both sides of the guide blade 63 is curved in order to reduce resistance to air flow. 
     At a central part of the second plate 62 of the duct 60 is installed a fan motor 70. 
     The first fan 71 facing the indoor heat exchanger 40 is installed at one side of the fan motor 70, and a second fan 72 facing the outdoor heat exchanger 50 is installed on the other side of the fan motor 70. A compressor 80 for compressing the refrigerant to high pressure and temperature is installed on a side of the base 30. 
     The compressor 80 compresses the gaseous refrigerant therein by a reciprocating movement of a piston or a rotational movement of a rotor. The compressed refrigerant flows into the outdoor heat exchanger 50. The liquid refrigerant at room temperature and high pressure which has undergone heat exchange is reduced in pressure by the capillary tube 51, and then flows into the indoor heat exchanger 40. 
     Meanwhile, the air in the room drawn through the suction grill 12 by the first fan 71 flows toward the indoor heat exchanger 40. The air is then cooled while it passes through the heat exchanger 40. The cooled air is drawn by the first fan 71, and is then discharged through the air passage of the duct 60 and the discharge grill 11, whereby the temperature in the room is maintained low. 
     The operation of such an air conditioner is substantially the same with that of a prior art air conditioner, except that in the air conditioner according to the present invention, since the guide blade 63 for distributing the air is installed in the part 60a of the air passage having broad sectional area, the air flowing through the parts 60a, 60b has substantially the same velocity and pressure. 
     In other words, due to the presence of the guide blade 63, the pressure of the air passing through the part 60a of the air passage becomes low and the velocity thereof becomes relatively fast. 
     Consequently, as shown in FIG. 5, the pressures and the velocities of the air flowing through the parts 60a, 60b of the air passage at both sides of the duct 60 are uniform while the cool air is discharged, so that a reentry of the discharged air into the passage is prevented and the velocity of the discharged air becomes uniform across the overall area of the discharge grill 11. 
     Although the preferred embodiment of the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, wherein the spirit and scope of the present invention is limited only by the terms of the appended claims.