Patent Description:
An air conditioner, which generally uses a refrigeration cycle to adjust temperature, humidity, flow and distribution of ambient air to levels proper for human activities and remove dust from the air, includes a compressor, a condenser, an evaporator and a blower fan.

Air conditioners may be divided into a split type air conditioner, which has an indoor unit and an outdoor unit separately installed, and an integrated type air conditioner, which has an indoor unit and an outdoor unit installed together in a cabinet.

The indoor unit of the split type air conditioner is provided with a heat exchanger to exchange heat with air suctioned into a panel, and a blower fan to suction the indoor air into the panel and blow the same to the room.

For the split type air conditioner, a blower fan is generally disposed at the lower portion of the indoor unit, and a heat exchanger and an air discharge outlet allowing air to be discharged therethrough are disposed at the upper portion of the indoor unit. The air suctioned and blown by the blower fan moves to the upper portion of the indoor unit, passes the heat exchanger and the air discharge outlet, and is then discharged to the room.

However, for the indoor unit having such structure as above, the vertical arrangement of the blower fan and the heat exchanger may not be efficient in view of space utilization.

Moreover, since the air from the blower fan is moved to the upper portion of the indoor unit and then discharged, the flow passage leading from the lower portion of the indoor unit to the upper portion thereof is long, and the load applied to the blower fan to blow the suctioned air is large. Thereby inefficient utilization of energy may be caused, and increase in the volume and speed of air flow may be limited.

In addition, if the heat exchanger and the blower fan are disposed too close to each other to realize a compact and slim design of the indoor unit, air resistance in heat exchange may increase, resulting in degradation of performance of the blower fan and increase in noise level during operation.

<CIT>, <CIT> and <CIT> each disclose an indoor unit of an air conditioner having a fan and a diffuser.

According to an aspect of the invention, there is provided an indoor unit of an air conditioner as set out in claim <NUM>.

Therefore, it is an aspect of the present invention to provide an indoor unit of an air conditioner provided with improved structures of suction, discharge and air flow passages to increase operational efficiency, lower noise level, and realize a compact size.

It is another aspect of the present invention to provide an indoor unit of an air conditioner which allows convenient adjustment of the flow direction and volume of air discharged from the indoor unit.

Additional aspects of the invention will be set forth in part in the description which follows.

These and/or other aspects of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings in which:.

As shown in <FIG>, the indoor unit of air conditioner <NUM> includes a housing <NUM> forming an external appearance of the indoor unit <NUM>, a plurality of diagonal flow fan units <NUM> disposed in the housing <NUM>, at least one heat exchanger <NUM> disposed at the rear of the diagonal flow fan units <NUM> in the housing <NUM> and a plurality of suction inlets <NUM> provided on the rear surface of the housing <NUM>.

The housing <NUM> includes a front panel <NUM> provided with a plurality of openings 112a allowing the discharge outlet 121a of the diagonal flow fan unit <NUM> to be exposed at the front side thereof, a rear panel <NUM> coupled to the rear side of the front panel <NUM>. The openings 112a are formed in a circular shape, and at least two thereof may be disposed spaced apart from each other in a vertical direction of the front panel <NUM>.

Each of the diagonal flow fan units <NUM> includes a diffuser <NUM> forming a discharge outlet 121a, a drive motor <NUM> coupled to the rear surface of the diffuser <NUM>, a diagonal flow fan <NUM> rotatably coupled to the drive motor <NUM>, and a duct <NUM> coupled to the rear surface of the diffuser <NUM> to form a flow passage 124a allowing the air suctioned by the diagonal flow fan <NUM> to move therethrough to be discharged to the discharge outlet 121a. In other words, the fan provides a suction force for the air to move it to the discharge outlet.

The diffuser <NUM> includes a circular disc plate 121b, a circular grille 121c coupled to the outer circumferential surface of the circular disc plate 121b, and a ring-shaped discharge outlet 121a formed between the circular disc plate 121b and the grille 121c. The diffuser <NUM> is disposed at the front side of the diagonal flow fan <NUM> to allow the air from the diagonal flow fan <NUM> to be discharged through the discharge outlet 121a to diverge in all directions toward the front of the front panel <NUM>.

Referring to <FIG>, the circular disc plate 121b is disposed at the center of the circular grille 121c. However, the position of the circular disc plate 121b is not limited to the center of the circular grille 121c. The diameter of the circular disc plate 121b, which is related to noise generated when air is discharged from the indoor unit <NUM> of an air conditioner, may be between <NUM> and <NUM>. In addition, although not shown in <FIG>, the circular disc plate 121b and the grille 121c may be adapted to move in a direction in which the air is discharged from the indoor unit <NUM> or the direction opposite thereto.

The grille 121c includes blade plates 121d, and the flow direction and flow rate of the air discharged through the discharge outlet 121a may be adjusted by changing the number, shape and orientation of the blade plates 121d.

The flow direction and volume of air discharged through the discharge outlet 121a may also be adjusted by widening or narrowing the radial width of the discharge outlet 121a through adjustment of the distance between the circular disc plate 121b and the grille 121c, or by changing the diameter of the circular disc plate 121b.

The drive motor <NUM> is coupled to the rear surface of the circular disc plate 121b with the rotating shaft 122a thereof arranged facing the rear panel <NUM>, and adapted to rotate the diagonal flow fan <NUM>.

The diagonal flow fan <NUM>, which functions as a fan to blow air introduced into the housing and is disposed between the diffuser <NUM> and the heat exchanger <NUM> to suction the air which has exchanged heat in the heat exchanger <NUM> and discharge the same to the discharge outlet 121a, includes a hub 123a coupled to the rotating shaft 122a of the drive motor <NUM>, and a plurality of blades 123b coupled to the outer circumferential surface of the hub 123a.

The diameter of the hub 123a gradually decreases in a direction toward the suction inlet 140and toward the rear panel <NUM>, and thereby the outer circumferential surface of the hub 123a is formed inclined. To allow the air suctioned by the diagonal flow fan <NUM> to be slantingly discharged toward the discharge outlet 121a, an angle α formed between the lines L1 and L3 extending along the inclined outer circumferential surface of the hub 123a and an imaginary line Lc passing through the center of the rotating shaft 122a of the drive motor <NUM> may be between about <NUM>° and about <NUM>°.

When the point at which the lines L1 and L3 extending along the inclined outer circumferential surface of the hub 123a meet each other is defined as P1, the point at which a line extending from P1 meets the center of the circular disc plate 121b as P2, the point at which the lines L1 and L3 extending along the inclined outer circumferential surface of the hub 123a meet the circular disc plate 121b or a line extending from the circular disc plate 121b as P3, and the distance between P2 and P3 as R, the radius of the circular disc plate 121b may be within a range between <NUM>. 8R and <NUM>. According to the Coanda effect, the circular disc plate 121b causes the air to flow along the surface thereof. Thereby, the circular disc plate 121b functions to suppress creation of a vortex on the front surface of the discharge outlet 121a due to flow of the air. When the circular disc plate 121b is within a range between <NUM>. 8R and <NUM>. 2R, an aesthetically pleasing external appearance may be provided and creation of a vortex on the front surface of the discharge outlet 121a may be suppressed, and thereby the performance of the indoor unit <NUM> may be increased.

At least three of the blades 123b are disposed equally spaced apart from each other along the outer circumferential surface of the hub 123a. When the blades 123b rotate together with the hub 123a, the blades 123b form a pressure gradient from the front side of the diagonal flow fan <NUM> to the rear side thereof to produce uniform flow of air.

The arc that connects the opposite lateral edges of the blade 123b is formed by two arcs having different radii of curvature. The boundary <NUM> between the first arc 129a and the second arc 129b may be positioned at a position close to the rear surface of the blade 123b beyond the center of the blade 123b. Thereby, the separation region in which the flow of air along the surface of the blade 123b is separated from the surface of the blade 123b may be narrowed compared to the case of having the boundary <NUM> between the first arc 129a and the second arc 129b positioned at the center or front surface of the blade 123b. Therefore, performance degradation of the indoor unit <NUM> due to separation may be prevented and, accordingly, noise level may be lowered.

When the shortest distance between one end of the blade 123b and the heat exchanger <NUM> disposed at the rear side of the diagonal flow fan unit <NUM> is defined as d1, the shortest distance d1 may be between about <NUM> and about <NUM>. If the shortest distance d1 is less than <NUM>, the distance between the diagonal flow fan <NUM> and the heat exchanger <NUM> may be shortened, resulting in generation of suction resistance and increase of noise during operation. If the shortest distance d1 is greater than <NUM>, the distance between the diagonal flow fan <NUM> and the heat exchanger <NUM> may be widened, and thereby the air having exchanged heat in the heat exchanger <NUM> may be not be smoothly suctioned into the diagonal flow fan <NUM>.

In addition, when the shortest distance between the heat exchanger <NUM> and the suction inlet <NUM> is defined as d2, the shortest distance d2 may be between about <NUM> and about <NUM>.

The duct <NUM> includes a flow passage forming duct 124a formed in a circular shape to surround the diagonal flow fan <NUM> and define, in cooperation with the hub 123a, a flow passage for the air suctioned by the diagonal flow fan <NUM> to flow to the discharge outlet 121a and a fixing plate 124b connected to the rear side of the flow passage forming duct 124a to fix the duct <NUM> within the housing <NUM>.

The flow passage forming duct 124a has an inclined lateral surface to allow the air suctioned by the hub 123a and the diagonal flow fan <NUM> to be slantingly discharged toward the discharge outlet 121a. The angle formed between the line L2 extending along the lateral surface of the flow passage forming duct <NUM> and the line Lp parallel to the imaginary line passing the center of rotation of the diagonal flow fan <NUM> may be between about <NUM>° and about <NUM>°. The diffuser <NUM> is coupled and fixed to the front surface of the inlet of the flow passage forming duct 124c, and the duct <NUM> is coupled and fixed to a fixing frame <NUM> through a fixing plate 124b formed in a rectangular shape.

As describe above, the hub 123a and the duct <NUM> function to guide the introduced air such that the air is discharged to the front through the discharge outlet 121a. Accordingly, the hub 123a and the duct <NUM> may be viewed respectively as a first guide unit and a second guide unit.

The heat exchanger <NUM> is disposed between the diagonal flow fan unit <NUM> and the suction inlet <NUM> to absorb heat from the air introduced through the suction inlet <NUM> or transfer heat to the air introduced through the suction inlet <NUM>. The heat exchanger <NUM> includes a tube <NUM>, and a header <NUM> attached to the upper and lower side of the tube <NUM>.

One or more heat exchangers <NUM> may be disposed in the indoor unit <NUM>. That is, a plurality of the heat exchangers <NUM> may be provided corresponding to the number of the diagonal flow fan units <NUM> and disposed respectively at the rear sides of the diagonal flow fan unit <NUM>, or a single heat exchanger <NUM> corresponding to the entire size of all the diagonal flow fan units <NUM> may be disposed. In addition, heat exchange capacity may vary among the heat exchangers <NUM>. That is, one of the heat exchangers <NUM> having a relatively low heat exchange capacity may be disposed at the rear side of a corresponding one of the diagonal flow fan units <NUM>, while another one of the heat exchangers <NUM> having a relatively large capacity of heat exchange may be disposed at the rear side of two or more diagonal flow fan units <NUM>.

The suction inlet <NUM> is provided on the rear panel <NUM> disposed at the rear side of the heat exchanger <NUM> to guide flow of air from outside the indoor unit <NUM> into the indoor unit <NUM>. The suction inlet <NUM> may be disposed on at least one of the top surface, lateral surfaces and rear surfaces of the rear panel <NUM>.

As in the case of the heat exchangers <NUM>, one or more suction inlets <NUM> may be provided on the rear panel <NUM>. To correspond to the respective diagonal flow fan units <NUM>, the suction inlets <NUM> corresponding in number to the number of the diagonal flow fan units <NUM> may be provided on the rear panel <NUM>, or a single suction inlet <NUM> corresponding to the entire size of the diagonal flow fan units <NUM> may be provided on the rear panel <NUM>. The sizes of the suction inlets <NUM> may be different from each other. That is, one of the suction inlets <NUM> may be disposed on a corresponding one of the diagonal flow fan units <NUM>, while another one of the suction inlets <NUM> may be disposed on at least two corresponding ones of the diagonal flow fan units <NUM>.

As shown in <FIG>, the air introduced into the housing <NUM> through the suction inlets <NUM> absorbs or loses heat while passing through the heat exchanger <NUM>. The air that has exchanged heat while passing the heat exchanger <NUM> is suctioned by the diagonal flow fan <NUM> and discharged to the outside of the housing <NUM> via the duct <NUM> and the discharge outlet 121a. Here, the angle formed by the direction in which the air is suctioned into the diagonal flow fan <NUM> and the direction in which the air is discharged through the discharge outlet 121a is between about <NUM>° and about <NUM>°.

The indoor unit <NUM> according to the illustrated embodiment may include a plurality of diagonal flow fan units <NUM>, a plurality of the heat exchangers <NUM> and a plurality of suction inlets <NUM>. A description will be given of a case in which the plurality of diagonal flow fan units <NUM>, the plurality of heat exchangers <NUM>, and the plurality of suction inlets <NUM> are arranged at the upper portion, middle portion and lower portion of the indoor unit <NUM> in a longitudinal direction of the indoor unit <NUM> as shown in <FIG>.

The plurality of diagonal flow fan units <NUM> includes a first diagonal flow fan unit 120a, a second diagonal flow fan unit 120b and a third diagonal flow fan unit 120c which are disposed spaced apart from each other in the longitudinal direction of the indoor unit <NUM>. The plurality of heat exchangers <NUM> includes a first heat exchanger 130a, a second heat exchanger 130b and a third heat exchanger 130c which are disposed spaced apart from each other between the diagonal flow fan units <NUM> and the suction inlets <NUM> in the longitudinal direction of the indoor unit <NUM>. The plurality of suction inlets <NUM> includes a first suction inlet 140a, a second suction inlet 140b and a third suction inlet 140c disposed at the rear side of the heat exchangers <NUM> spaced apart from each other in the longitudinal direction of the indoor unit <NUM>.

The first diagonal flow fan unit 120a, the first heat exchanger 130a and the first suction inlet 140a are arranged in a row. The second diagonal flow fan unit 120b, the second heat exchanger 130b and the second suction inlet 140b are arranged in a row under the first diagonal flow fan unit 120a, the first heat exchanger 130a and the first suction inlet 140a. The third diagonal flow fan unit 120c, the third heat exchanger 130c and the third suction inlet 140c are arranged in a row under the second diagonal flow fan unit 120b, the second heat exchanger 130b and the second suction inlet 140b.

As the diagonal flow fan units 120a, 120b and 120c, the heat exchangers 130a, 130b and 130c, and the suction inlets 140a, 140b and 140c disposed at the upper, middle and lower portions of the indoor unit <NUM> in the longitudinal direction of the indoor unit <NUM> are arranged in horizontal rows, the indoor unit <NUM> may have a slim width. In addition, as the flow passage between the suction inlet <NUM> and the discharge outlet 121a is shortened, the operational efficiency of the indoor unit <NUM> may be increased, while the noise level is lowered.

The first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c may be independently turned on/off and controlled to rotate at different speeds. The first heat exchanger 130a, the second heat exchanger 130b and the third heat exchanger 130c corresponding respectively to the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c may be independently controlled such that a refrigerant is supplied thereto depending on the operational state (ON/OFF) of the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c. For example, when the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b are operated (turned on) and the third diagonal flow fan unit 120c is at rest (turned off), the refrigerant may be controlled to be supplied to the first heat exchanger 130a and the second heat exchanger 130b corresponding to the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b but not to be supplied to the third heat exchanger 130c corresponding to the third diagonal flow fan unit 120c.

Although not shown, supply of refrigerant to the first heat exchanger 130a may be controlled by installing valves to shut off the flow passages between refrigerant pipes respectively connected to the first heat exchanger 130a, the second heat exchanger 130b and third heat exchanger 130c and each of the third heat exchanger 130c, the second heat exchanger 130b and the third heat exchanger 130c or by installing a single valve (e.g., a <NUM>-way valve) having a plurality of ports connected to the first heat exchanger 130a, the second heat exchanger 130b and third heat exchanger 130c. As such valves, a pneumatic valve and an electronic valve using a solenoid may be used.

Hereinafter, a description will be given of a method of controlling such an indoor unit <NUM> of an air conditioner having a structure as above.

<FIG> is a view illustrating the temperature distribution of air discharged from the discharge outlet in respective operation modes of the indoor unit of the air conditioner according to the illustrated embodiment of the present invention, <FIG> is a view illustrating a control system of the air conditioner according to the illustrated embodiment of the present invention, and <FIG> is a view illustrating a method of controlling the air conditioner according to the illustrated embodiment of the present invention, based on <FIG>.

<FIG> shows the temperature distribution of the air discharged from the discharge outlet 121a in respective operation modes of the indoor unit <NUM> of the air conditioner according to the illustrated embodiment of the present invention. The indoor unit <NUM> is provided with a plurality of diagonal flow fan units 120a, 120b and 120c which are arranged in a vertical direction (or a longitudinal direction of the indoor unit <NUM>) and perform a desired air conditioning operation by adjusting the flow rate and speed of the air discharged from the diagonal flow fan units 120a, 120b and 120c. The adjustment of the flow rate and speed of the air discharged from the diagonal flow fan units 120a, 120b and 120c is implemented by independently turning on/off the diagonal flow fan units 120a, 120b and 120c and independently controlling the rate of rotation (RPM) of each of the diagonal flow fan units 120a, 120b and 120c.

In <FIG>, reference numeral <NUM> represents the bottom surface of the air conditioning space. Reference numeral <NUM> represents the ceiling of the air conditioning space, which is about <NUM> above the bottom surface <NUM>. Reference numeral <NUM> represents a breathing line at a level (e.g. about <NUM>) at which the nose and eyes of an adult of average height (e.g., about <NUM>) are arranged.

<FIG> shows a first operation mode, in which the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c are all operated (turned on), and the rates of rotation of the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c are different from each other. That is, <FIG> shows a case in which the rate of rotation of the first diagonal flow fan unit 120a is <NUM> RPM, the rate of rotation of the second diagonal flow fan unit 120b is <NUM> RPM, and the rate of rotation of the third diagonal flow fan unit 120c is <NUM> RPM. In this case, the refrigerant may be controlled to be supplied to all of the first heat exchanger 130a, the second heat exchanger 130b and the third heat exchanger 130c respectively corresponding to the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c.

Since the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c are all operated (turned on), a large amount air is discharged and transferred to a far distance, and thus this operation is suitable for air conditioning of a wide area.

<FIG> shows a second operation mode, in which the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c are all operated (turned on), and the rates of rotation of the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c are controlled differently from each other. In this mode, the rates of rotation of the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b are lower than in the mode of <FIG>. That is, the rate of rotation of the first diagonal flow fan unit 120a is <NUM> RPM, the rate of rotation of the second diagonal flow fan unit 120b is <NUM> RPM, and the rate of rotation of the third diagonal flow fan unit 120c is <NUM> RPM. In this case, the refrigerant may be controlled to be supplied to all of the first heat exchanger 130a, the second heat exchanger 130b and the third heat exchanger 130c respectively corresponding to the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c, as in the first mode.

In the case of <FIG>, the air conditioning effect reaches a distance similar to that in <FIG>, but the air conditioning is usually implemented below the breathing line <NUM>. In this case, the rates of rotation of the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b are relatively low compared to the case of <FIG>, and thus quiet operation may be possible and energy consumption may be reduced even though the height the effect of air conditioning reaches is relatively low compared to the case shown in <FIG>.

<FIG> shows a third operation mode, in which the first diagonal flow fan unit 120a is at rest (turned off), the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c are operated (turned on), and the rates of rotation of the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c are different from each other. That is, the first diagonal flow fan unit 120a is maintained at rest, the rate of rotation of the second diagonal flow fan unit 120b is 1000RPM, and the rate of rotation of the third diagonal flow fan unit 120c is 1400RPM. In this case, the refrigerant may be controlled not to be supplied to the first heat exchanger 130a corresponding to the first diagonal flow fan unit 120a, while being supplied to the second heat exchanger 130b and the third heat exchanger 130c corresponding respectively to the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c.

Compared to the cases of <FIG>, the distance and height that the effect of air conditioning in <FIG> reaches further decrease. In case of <FIG>, the first diagonal flow fan unit 120a is not operated, and thus quiet operation may be possible and energy consumption may be reduced even though the area that the effect of air conditioning reaches is relatively small compared to those of <FIG>.

<FIG> shows a fourth operation mode, in which the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b are at rest (turned off), and the third diagonal flow fan unit 120c alone is operated (turned on). The rate of rotation of the third diagonal flow fan unit 120c is 1400RPM. In this case, the refrigerant may be controlled not to be supplied to the first heat exchanger 130a and the second heat exchanger 130b corresponding to the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b, while being supplied to the third heat exchanger 130c corresponding to the third diagonal flow fan unit 120c.

Compared to the cases of <FIG>, the distance and height that the effect of air conditioning in <FIG> reaches greatly decrease. In case of <FIG>, the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b are not operated, and thus quieter operation and reduction of energy consumption may be achieved even though the area that the effect of air conditioning reaches is relatively small compared to those of <FIG>. The mode of <FIG> is useful when air conditioning effect needs to be concentrated at an area in the air conditioning space which is close to the front surface of the indoor unit <NUM>.

The control of turning on/off the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c and the rates of rotation thereof is not limited to the embodiments of <FIG>. Various air conditioning effects may be realized through various combinations.

<FIG> shows a control system of the air conditioner according to the illustrated embodiment of the present invention. As shown in <FIG>, an input unit <NUM>, an outdoor temperature sensor <NUM>, an indoor temperature sensor <NUM>, and an evaporator temperature sensor <NUM> are electrically connected to the input side of the controller <NUM>, which controls overall operation of the air conditioner, to communicate with the controller <NUM>, while a compressor <NUM>, an electronic expansion valve <NUM>, a first fan drive unit 816a, a second fan drive unit 816b, and a third fan drive unit 816c are electrically connected to the output side of the controller <NUM> to communicate with the controller <NUM>. The first fan drive unit 816a, the second fan drive unit 816b and the third fan drive unit 816c, which function to respectively drive the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c, operate according to commands from the controller <NUM> to turn on/off the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c and control the rates of rotation thereof. The controller <NUM> transfers commands respectively to the first fan drive unit 816a, the second fan drive unit 816b and the third fan drive unit 816c to control ON/OFF and the rates of rotation of the first diagonal flow fan unit 120a, the second diagonal flow fan unit 120b and the third diagonal flow fan unit 120c in correspondence with an operation mode selected by a user.

<FIG> shows a method of controlling the air conditioner according to the illustrated embodiment of the present invention, based on <FIG>. The control method in <FIG> is performed by the control system shown in <FIG>. As shown in <FIG>, when the user turns on the air conditioner and selects a desired operation mode, the controller <NUM> of the air conditioner receives the information about the operation mode selected by the user, generates a control signal corresponding to the received operation mode and transfers the signal to each part of the air conditioner such that the targeted operation is implemented (<NUM>).

If the selected operation mode is the first operation mode, the controller <NUM> transfers a control command for implementation of the first operation mode to the first fan drive unit 816a, the second fan drive unit 816b and the third fan drive unit 816c such that the first diagonal flow fan unit 120a rotates at <NUM> RPM, the second diagonal flow fan unit 120b rotates at <NUM> RPM, and the third diagonal flow fan unit 120c rotates at <NUM> RPM (<NUM>).

If the selected operation mode is the second operation mode, the controller <NUM> transfers a control command for implementation of the second operation mode to the first fan drive unit 816a, the second fan drive unit 816b and the third fan drive unit 816c such that the first diagonal flow fan unit 120a rotates at <NUM> RPM, the second diagonal flow fan unit 120b rotates at <NUM> RPM, and the third diagonal flow fan unit 120c rotates at <NUM> RPM (<NUM>).

If the selected operation mode is the third operation mode, the controller <NUM> transfers a control command for implementation of the third operation mode to the first fan drive unit 816a, the second fan drive unit 816b and the third fan drive unit 816c such that first diagonal flow fan unit 120a is turned off, the second diagonal flow fan unit 120b rotates at <NUM> RPM, and the third diagonal flow fan unit 120c rotates at <NUM> RPM (<NUM>).

If the selected operation mode is the fourth operation mode, the controller <NUM> transfers a control command for implementation of the fourth operation mode to the first fan drive unit 816a, the second fan drive unit 816b and the third fan drive unit 816c such that the first diagonal flow fan unit 120a and the second diagonal flow fan unit 120b are turned off, and the third diagonal flow fan unit 120c rotates at <NUM> RPM (<NUM>).

When the selected operation mode is implemented as above and completed, the operation of the air conditioner is terminated (<NUM>).

<FIG> is a view illustrating an indoor unit of an air conditioner according to another embodiment of the present invention, and <FIG> is a view illustrating the indoor unit shown in <FIG>, in which the front panel is separated from the indoor unit.

As shown in <FIG> and <FIG>, the indoor unit <NUM> includes one diagonal flow fan unit 120a, and an opening 112a is provided in the front panel <NUM> to couple the diagonal flow fan unit 120a to the front panel <NUM>. Other configurations and operational mechanism are the same as those of the indoor unit of air conditioner <NUM> according to the previous embodiment of the present invention and thus a detailed description thereof will be omitted.

<FIG> is a view illustrating an indoor unit of an air conditioner according to another embodiment of the present invention, and <FIG> is a cross-sectional view illustrating the indoor unit shown in <FIG>.

As shown in <FIG> and <FIG>, a diffuser <NUM> of a diagonal flow fan unit <NUM> of an indoor unit <NUM> includes a guide vane <NUM> to prevent the diagonal flow fan <NUM> from being exposed through the discharge outlet 121a and guide flow of air discharged through the discharge outlet 121a.

The guide vane <NUM>, arranged between a circular disc plate 121b and a grille 121c, may include a first vane 173a spaced apart from the circular disc plate 121b in a circumferential direction and formed in a ring shape, and a second vane 153b extending from the outer circumferential surface of the first vane 173a to the inner circumferential surface of the grille 121c.

The first vane 173a may include a radial inner surface facing the circular disc plate 121b, and a radial outer surface facing the grille 121c.

The rear end of the inner surface of the first vane 173a, which is positioned at the inner side of the discharge outlet 121a, may be formed to be inclined with respect to the axial direction of the diagonal flow fan <NUM>, as in the case of the flow passage forming duct 124a. However, the inclination angle may decrease as the inner surface extends from the rear end to the front such that the front portion thereof is parallel to the axial direction of the diagonal flow fan <NUM>.

The rear end of the radial inner lateral surface of the first vane 173a may be formed to have a predetermined inclination with respect to the axial direction of the diagonal flow fan <NUM>, but the inclination may decrease as the radial inner lateral surface extends from the rear end thereof to the front such that the front end thereof is parallel to the axial direction of the diagonal flow fan <NUM>.

By the first vane 173a formed as above, part of cool air slantingly discharged by the diagonal flow fan <NUM> and the flow passage forming part 124a with respect to the axial direction of the diagonal flow fan <NUM> is guided in the axial direction of the diagonal flow fan <NUM> through the inner and outer surfaces of the first vane 173a. In addition, the radial outer surface of the first vane 173a is generally curved outward, and thus the cross section of the first vane 173a may be generally provided in a streamline shape. Accordingly, the cool air discharged from the discharge outlet 121a in the direction parallel to the axial direction of the diagonal flow fan <NUM> by the first vane 173a is guided out of the discharge outlet 121a and allowed to reach a far distance from the discharge outlet 121a, and the cool air discharged from the discharge outlet 121a at an inclination angle with respect to the axial direction of the diagonal flow fan <NUM> is allowed to reach an area of wide angle from the discharge outlet 121a.

The second vane 173b may be radially formed in the discharge outlet 121a, and multiple second vanes 173b may be arranged equally spaced apart throughout the entirety of the discharge outlet 121a. In addition, the second vane 173b may be formed in a curved line to rotate in one direction about the axis of the diagonal flow fan <NUM> to guide formation of a rotating air stream when the cool air is discharged from the discharge outlet 121a.

The rotating air stream formed in the discharged air stream may function to extend the discharge distance such that the cool air reaches a considerable distance from the indoor unit <NUM>.

The diffuser <NUM> provided with the first vane 173a and the second vane 173b as above may be formed by injection molding, and the first vane 173a and the second vane 173b may be integrated with the grille 121c formed around the circular disc plate 121b and the discharge outlet 121a.

In the illustrated embodiment, one first vane 173a is provided in the discharge outlet 121a. However, this is simply for illustration, and a plurality of first vanes 173a may be provided in the discharge outlet 121a in a radial direction.

Other constituents and operational mechanisms are the same as those of the indoor unit <NUM> of an air conditioner according to the previous embodiment and thus a detailed description thereof will be omitted.

<FIG> is a view illustrating an indoor unit of an air conditioner according to a further embodiment of the present invention. <FIG> is a view showing the shape of a diffuser (a) of an indoor unit of an air conditioner according to the conventional art and the shape of a diffuser (b) of an indoor unit of an air conditioner according to another embodiment of the present invention. <FIG> is an enlarged view showing section 'B' of <FIG>, and <FIG> is a perspective view of <FIG>.

As shown in <FIG>, a diffuser <NUM> of a diagonal flow fan unit <NUM> of an indoor unit <NUM> includes a circular disc plate 121b, a circular grille 121c coupled to the outer circumferential surface of the circular disc plate 121b, a ring-shaped discharge outlet 121a formed between the circular disc plate 121b and the grille 121c. The diffuser <NUM> is disposed at the front of a diagonal flow fan <NUM> to discharge the air passing the diagonal flow fan <NUM> to the outside of the front panel <NUM> through the discharge outlet 121a. The grille 121c includes blade plates 421d, and the flow direction and flow rate of the air discharged through the discharge outlet 121a may be adjusted by changing the number, shape and orientation of the blade plates 421d.

The blade plate 421d is formed in the shape of a spiral blade to extend from the circular disc plate 121b to the grille 121c, and thereby guiding discharge of the air blowing from the diagonal flow fan <NUM> to the outside.

The blade plate 421d is formed to extend from the circular disc plate 121b to the grille 121c in a first direction. The first direction, which may be one of various directions including a spiral direction and a radial direction extending from the circular disc plate 121b to the grille 121c, is assumed to be the radial direction in the illustrated embodiment.

The blade plate 421d extends in the first direction and is curved in a direction opposite to that of rotation of the diagonal flow fan <NUM>. If the diagonal flow fan <NUM> rotates clockwise when viewed from the front of the diffuser <NUM>, the blade plate 421d extends from the circular disc plate 121b to the grille 121c and is curved counterclockwise. If the diagonal flow fan <NUM> rotates counterclockwise, the blade plate 421d extends from the circular disc plate 121b to the grille 121c and is curved clockwise.

In conventional cases, if the blade plate <NUM> extends from a disc plate <NUM> to a grille <NUM> and is curved clockwise, i.e., if the blade plate <NUM> is curved in the same direction as that of rotation of the diagonal flow fan <NUM>, the discharged air blowing from the diagonal flow fan <NUM> is guided by the blade plate <NUM> to form a diffuse air stream rather than a front air stream. In contrast, when the blade plate is configured as in the illustrated embodiment, diffusing of the discharged air in all directions is blocked and instead the diffuse air stream is transformed into a front air stream by the blade plate 421d. That is, when the axis lying in the direction toward the front of the diffuser <NUM> is defined as the z-axis, the axis lying in a radial direction toward the center of the diffuser <NUM> is defined as the y-axis and the axis lying in the direction of the tangent line of the diffuser <NUM> having a circular shape is defined as the x-axis, components of the discharged air from the diagonal flow fan <NUM> blowing in the directions of the x and y axes are guided to the z-axis by the blade plate 421d.

The shape of the spiral blade of the blade plate 421d may be formed by a rib having a predetermined width. The blade plate 421d serves to protect the internal components of the indoor unit <NUM> such as the diagonal flow fan <NUM>, but is primarily intended to guide discharged air from the diagonal flow fan <NUM> to form an air stream. Therefore, the blade plate 421d is formed by a rib having a predetermined width sufficient to guide the discharged air.

The blade plate 421d includes a front portion <NUM> facing in the front direction, and a rear portion <NUM> facing in the rear direction. The angle at which the front portion <NUM> is curved is different from the angle at which the rear portion <NUM> is curved. The blade plate 421d may be divided, with respect to the middle portion of the lateral surface, into the front portion <NUM> facing in the front direction of the front panel and the rear portion <NUM> facing in the rear direction of the front panel. The blade plate 421d extends in a first direction heading from the circular disc plate 121b to the grille 121c, and is curved in a direction opposite to the direction of rotation of the diagonal flow fan <NUM>.

Curving the front portion <NUM> and the rear portion <NUM> at different angles is more effective in forming a front air stream.

In the configuration as above, the rear portion <NUM> is more curved than the front portion <NUM> in consideration of formation of a front air stream. The rear portion <NUM> is more curved than the front portion <NUM>, and thus as the blade plate 421d extends from the rear portion <NUM> to the front portion <NUM>, the lateral surface of the blade plate 421d becomes approximately parallel to the front surface of the diffuser <NUM>, i.e., to the z-axis. Thereby, the air discharged from the diagonal flow fan <NUM> is first guided by the rear portion <NUM> along the lateral surface of the blade plate 421d and is then guided by the front portion <NUM> toward the front of the diffuser <NUM> to form a front air stream.

The grille 121c is formed in an annular shape. Thereby, when the discharged air from the diagonal flow fan <NUM> is discharged through the discharge outlet 121a in the front direction of the front panel <NUM>, the grille 121c serves to prevent the discharged air stream from being diffused upward, downward leftward and rightward and guide the discharged air.

In addition, the flow direction and flow rate of the air discharged through the discharge outlet 121a may be adjusted by widening or narrowing the radial width of the discharge outlet 121a through adjustment of the distance between the circular disc plate 121b and the grille 121c, or by adjusting the diameter of the circular disc plate 121b.

<FIG> are views illustrating flows of discharged air generated by a diffuser of an indoor unit of an air conditioner according to the conventional art and a diffuser of an indoor unit of an air conditioner according to another embodiment of the present invention.

As shown in <FIG>, when the direction of rotation of the diagonal flow fan <NUM> is the same as the direction in which the blade plate <NUM> is curved as in the case of the diffuser <NUM> according to the conventional art, air is discharged upward, downward, leftward and rightward as the diagonal flow fan <NUM> rotates, and as a result, the air stream is discharged to diffuse. In contrast, in case of the diffuser <NUM> according to the illustrated embodiment of the present invention, the direction of rotation of the diagonal flow fan <NUM> is opposite to the direction in which the blade plate 421d is curved, and therefore the discharged air from the diagonal flow fan <NUM> is prevented from being diffused by the blade plate 421d, but is directed in the forward direction as it is guided from the rear portion <NUM> to the front portion <NUM> of the blade plate 421d.

In addition, in case of the conventional diffuser <NUM>, orientation of the blade plate <NUM> in the direction of rotation of the diagonal flow fan <NUM> further develops diffuse air stream in the discharged air, causing the discharged air to diffuse in all directions from the front of the air conditioner. In case of the diffuser <NUM> according to the illustrated embodiment of the present invention, on the other hand, the blade plate 421d curved in the direction opposite to the direction of rotation of the diagonal flow fan <NUM> develops a front air stream more than a diffuse air stream, thereby allowing the front air stream to be transferred a great distance from the front of the air conditioner.

As is apparent from the above description, an indoor unit of an air conditioner according to the present invention has a suction inlet, a heat exchanger, a diagonal flow fan and a discharge outlet arranged in a row and thus simplifies the air flow passage, and thereby the efficiency of the indoor unit may increase and a compact size thereof may be realized.

In addition, multiple diagonal flow fans are independently controllable to facilitate adjustment of the flow direction and flow rate of air, and therefore convenience in using the indoor unit may be enhanced.

Claim 1:
An indoor unit (<NUM>, <NUM>, <NUM>, <NUM>) of an air conditioner comprising:
a housing (<NUM>) including a front panel in which at least one opening (112a) is formed;
at least one diffuser (<NUM>) disposed at a position corresponding to the at least one opening (112a) and including a discharge outlet (121a);
a drive motor (<NUM>) coupled to a rear surface of the diffuser (<NUM>); and
a diagonal flow fan (<NUM>) rotatably coupled to the drive motor (<NUM>),
wherein the diffuser (<NUM>) includes:
a circular disc plate (121b); and
a grille (121c) disposed at an outer side of an outer circumferential surface of the circular disc plate (121b) in a radial direction of the circular disc plate (121b) to form the discharge outlet (121a) between the grille (121c) and the circular disc plate (121b),
wherein the grille (121c) includes a plurality of blade plates (121d, 421d) extending from the outer circumferential surface of the circular disc plate (121b) to an inner circumferential surface of the grille (121c) in the radial direction of the circular disc plate (121b), and each blade plate (121d, 421d) is formed in a curved shape in a direction opposite to a direction of rotation of the diagonal flow fan (<NUM>),
wherein each blade plate (121d, 421d) comprises a front portion (<NUM>) facing in a front direction and a rear portion (<NUM>) facing in a rear direction, and
characterised in that the curvature of the rear portion (<NUM>) of each blade plate (121d, 421d) is larger than the curvature of the front portion (<NUM>) of each blade plate (121d, 421d).