1. Field of the Invention
The present invention relates to an air path inside an indoor unit (air handler) of an air conditioner. More specifically, the present invention relates to an indoor unit of an air conditioner, in which at least one air inlet is formed at part or entire bottom surface of the indoor unit and an evaporator is installed between the air inlets and a blowing fan so that indoor air sucked in through air inlets passes through the evaporator and is discharged from an outlet vent formed at the front surface of the indoor unit by the operation of a blowing fan.
2. Discussion of the Background Art
FIG. 1 is a schematic diagram of a related art air conditioner.
Referring to FIG. 1, the related art air conditioner includes an outdoor unit (the condensing unit) 10 disposed outside of a building for heat exchange with outdoor air, an indoor unit (the air handler) 20 disposed inside of a building for circulating and delivering the cooled air, and a series of connecting duct 30 for connecting the outdoor unit 10 to the indoor unit 20.
To be more specific, the outdoor unit 10 pumps low-temperature, low-pressure vaporized refrigerant from the indoor unit 20, compresses it, and liquefies it to low-temperature, low-pressure refrigerant. The outdoor unit 10 includes a compressor 11, a condenser 12, and an expansion valve 13.
The compressor 11 changes the low-temperature, low-pressure vaporized refrigerant from the indoor unit 20 to high-temperature, high-pressure vaporized refrigerant The condenser 12 changes the high-temperature, high-pressure vaporized refrigerant to mid-temperature, high-pressure liquefied refrigerant. The expansion valve 13 changes the mid-temperature, high-pressure liquefied refrigerant to low-temperature, low-pressure liquefied refrigerant.
Among these components, the condenser 12 is the one that is directly involved in heat exchange with outdoor air. Thus, it has a separate fan 12a for blowing air from outside.
On the other hand, the indoor unit 20 changes low-temperature, low-pressure liquefied refrigerant from the outdoor unit 10 to low-temperature, low-pressure vaporized refrigerant and as a result thereof, the indoor temperature goes down. Thus, the indoor unit 20 includes an evaporator coil 21, and a fan 21a. 
The connecting duct 30 connects the outdoor unit 10 to the indoor unit 20, and allows the refrigerant to flow therein. Its position is determined depending on the distance between the outdoor unit 10 and the indoor unit 20.
As explained above, the air conditioner in general has a built-in refrigeration cycle that includes a compressor, a condenser, a capillary expansion valve, and an evaporator coil as a heat exchanger. When the temperature outside begins to climb, the air conditioner provides the cool comfort of indoor air conditioning by controlling the amount of cool air generated by the evaporator coil and hot air generated in the condenser.
Air conditioners are classified into two types: window air conditioners that implements the refrigeration cycle in a body and is small enough to fit into a window frame, and split air conditioners that allows the indoor unit (air handler) to be installed in a different location from the outdoor unit (the condenser). Especially the split air conditioners, depending on where the air conditioner is installed, are divided into wall-mounted split air conditioners, floor standing split air conditioners (including package air conditioners), ceiling-mounted split air conditioners, and ceiling cassette split air conditioners. Particularly, portable indoor units that can be placed on the wall, the floor or the ceiling at users' convenience are called convertible indoor units.
In short, the outdoor unit includes a noise generating compressor, a condenser, and a cooling fan, and the indoor unit includes an evaporator coil and a blowing fan.
Now referring to FIGS. 2 and 3, an indoor unit 1 of an air conditioner includes a rectangular shaped case 10; air inlets 12 formed at the center of the front surface of the case 10 for sucking up indoor air; a blowing fan 14 installed inside the case 10 and guiding the indoor air to the air inlet 12 through rotation; an evaporator coil 16 installed between the indoor air inlet 12 and the blowing fan 14, and generating cooled air by performing heat change between a refrigerant and the indoor air that is flown in the case 10 by the blowing fan 14; and an outlet vent formed on the edge of the front surface of the case 10 or on the upper/lower part of the case 10 to discharge the cooled air formed by the operation the evaporator coil 16 back to the indoor through the operation of the blowing fan 14.
The operational process of the related art indoor unit is now described below.
Low-temperature, low-pressure liquid expanded refrigerant from the outdoor unit (10 in FIG. 1) flows in the evaporator coil 16 inside the indoor unit (1 in FIG. 2), and at the same time, the indoor air flows in the indoor unit 1 through the air inlet 12 formed at the center of the front surface of the indoor unit 1 by the rotation of the blowing fan 14. Then the indoor air is cooled through heat change with the refrigerant traveling in the pipe of the evaporator coil 16, and by the operation of the blowing fan 14 the cooled air is discharged to the indoor through the outlet vent 18 that is formed either on the same surface where the air inlet 12 is formed, namely on the edge of the front surface of the case 10 as shown in FIG. 3(a), or on the upper/lower part of the case 10 as shown in FIG. 3(b). This process is repeated until indoor air conditioning is sufficient.
However in the related art indoor unit 1 the duct from the air inlet 12 formed at the center of the front surface of the indoor unit 1 en route to the outlet vent 18 via the evaporator coil 16 and the blowing fan 14 is typically in a “U” shape or “L” shape. Therefore, air flow resistance in the duct was great, and because of this, the indoor unit 1 usually generated a lot of noises.
Another problem arises when both the air inlet 12 and the outlet vent 18 are formed on the front surface of the indoor unit as shown in FIG. 3(a). In such case, the size or the area of the air inlet 12 is naturally limited by the size of the outlet vent 18. The limitation set on the size or the area of the air inlet 12 also affects the size or the area of the evaporator coil 16. Typically in the indoor unit of the related art air conditioner, the evaporator coil 16 is as big as the air inlet 12, or a little smaller than the air inlet 12.
The limitation set on the size or the area of the air inlet 12 and the evaporator coil 16 is a main factor of the deterioration of work efficiency of the evaporator coil 16 for performing heat exchange between the refrigerant and the indoor air flown into the indoor unit 1.
Moreover, the installation of the indoor unit 1 had to be very careful to place it in a position where air passage can be smooth in the “U” shaped duct from the air inlet 12 to the outlet vent 18, provided that the air inlet 12 and the outlet vent 18 are formed on the same surface.
As shown in FIGS. 3(a) and 3(b), the air inlet 12 and the outlet vent 18, or the air inlet 12 alone is formed on the front surface of the indoor unit 1. Therefore, it is not easy to engrave a logo or a pattern on the limited space or to coat the front surface of the indoor unit 1 with a unique finishing material on the front surface for the purpose of decoration.