FIELD OF THE INVENTION
[0001J The present invention relates to ail outdoor unit of an inverter air conditioner, and more specifically, to system and method for hybrid cooling of an outdoor unit of an air conditioner.
BACKGROUND OF THE INVENTION •
[0002] Conventional air conditioners that are used for cooling indoor environment work on principle of indoor air heat absorption by refrigerant in evaporator coil of Indoor unit and rejecting this heat to outdoor side through vapour compression refrigerant cycle including a compressor, a condenser and an expansion device, such as a capillary expansion device. Evaporator returns cool air back at low temperature to the room. Outdoor unit has two section - Compressor section and Fan Motor section. Both these sections are separated by a metal sheet partition wall. Usually, when the air conditioner is running, the compressor and other components are heated up and are at a higher temperature than the ambient temperature which makes air conditioners more vulnerable to failure. Higher temperature of compressor body, other electric components and poor air circulation causes increase in the overall temperature of the compressor section of outdoor unit of the air conditioners. Although the outdoor units are provided with condensing fans to remove hot air outside the outdoor unit, the condensing fan alone is not effective in reducing the overall temperature of the compressor section of outdoor unit. If the overall average outdoor unit temperature goes beyond 50 °C it reduces the efficiency and working life of the air conditioner.
[0003] Nowadays, air conditioners in market are available with inverter PCB technology to reduce power consumption and improve working efficiency of the air conditioner. Inverter PCB is placed in Metal / Plastic enclosure and fitted in the compressor section, just above compressor. However, these air conditioners are capable of working at ambient temperatures ur) to 50 °C and mostly deliver poor results at ambient temperatures higher than 50 °C. Even when the ambient temperature of air is not 50-55 deg C, the temperature inside the compressor section of outdoor unit of the air conditioner is 1-5 degrees higher than the ambient

temperature due to excessive heating caused internally. The inverter PCB and compressor fitted with the inverter AC are mainly responsible for increasing the internal temperature of the compressor section of outdoor unit of the air conditioners. [0004] For places where the average ambient temperature is above 50 °C, the inverter air conditioner that could deliver efficient results and with reliable components is required. Therefore, there have been proposals in the past to improve the efficiency of inverter air conditioners. It is Imown in the prior art that the outlet unit of the air conditioners could be provided w'ith sub-cooling to reduce its overall temperature. However, the same has not been effective at higher temperatures. [0005] Thus, in conventional inverter air conditioners there is excessive heating of internal parts of the outdoor unit which causes failure of the PCB components and tripping of compressor at ambient temperature higher than 50 °C. [0006] In view of the above mentioned drawbacks there is a need to provide a system and method which can increase overall product efficiency and service life of the inverter air conditioners.
OBJECTS OF THE INVENTION
[0007] It is an object of the present invention to provide a system and a method
for hybrid cooling of outdoor unit of an inverter air conditioner that works at high
ambient temperature, i.e., upto 55 °C.
[0008] It is another object of the present invention to provide a system and a
method for hybrid cooling of outdoor unit of an inverter air conditioner that works
even at low voltage of 195 Volts at elevated temperature of 55 °C.
[0009] It is another object of the present invention to provide a system and a
method for hybrid cooling of outdoor unit of an inverter air conditioner that reduces
temperature of PCB by 1 to 2 °C.
[00010] It is another object of the present invention to provide a system and a
method for hybrid cooling of outdoor unit of an inverter air conditioner that reduces
temperature of compressor by 1 to 2 °C.

[00011] An aspect of the present invention relates to a system and method for
hybrid cooling of an outdoor unit of an inverter air conditioner. The hybrid cooling
system includes a compressor chamber for receiving low pressure and low
temperature refrigerant from an indoor unit of the inverter air conditioner and
converting the low pressure and low temperature refrigerant into high pressure and
high temperature refrigerant, a condensing unit for condensing the high pressure and
high temperature refrigerant, said condensing unit including an outlet pipe to convey
the condensed refrigerant to a metallic heat sink in contact with an inverter printed
circuit board PCB of the outdoor unit, and at least one partition panel including a
plurality of slots to allow ingress of external ;air at ambient temperature inside the
compressor chamber, wherein when the condensed refrigerant comes in contact with
the metallic heat sink that is in contact with the inverter PCB, operating temperature
of the PCB is reduced, and wherein flow of the external air at ambient temperature
inside the compressor chamber enables reduction in operating temperature of the
compressor chamber.
[00012] In an embodiment, flow of the external air at ambient temperature
flowing inside the compressor chamber allows reduction in operating temperature of
the compressor chamber by a factor ranging from 1 °C to 2 °C.
[00013] In an embodiment, when the condensed refrigerant comes in contact with
the metallic heat sink, operating temperature of the inverter PCB is reduced by a
factor ranging from 1 °C to 2 °C.
[00014] In an embodiment, the metallic heat sink is made up of aluminium.
[00015] In an embodiment, the inverter PCB is arranged internally at a top
portion of the outdoor unit.
[00016] In an embodiment, the condensing unit includes a condensing fan for
drawing out hot air from the compressor chamber into an open space.
[00017] In an embodiment, the external air at ambient temperature is drawn into
the combustion chamber through a vent arrangement and the plurality of slots of the
at least one partition panel.
[00018] In an embodiment, the condensed refrigerant after passing through the
metallic heat sink flows into the indoor unit for expansion and recirculation.

[00019] In an embodiment, dimension of the metallic heat sink is 50 mm X 168 mm.
[00020] In an embodiment, length of the outlet pipe is in the range of 320 mm to 400 mm.
[00021] Another aspect of the present invention relates to a method for hybrid cooling of outdoor unit of an inverter air conditioner. The method includes the steps of receiving low pressure and low temperature refrigerant from an indoor unit of the inverter air conditioner and converting the low pressure and low temperature refrigerant into high pressure and high temperature refrigerant by a compressor chamber, condensing the high pressure and high temperature refrigerant, conveying the condensed refrigerant to a metallic heat sink in contact with an inverter PCB of the outdoor unit to enable reduction in operating temperature of the PCB when the condensed refrigerant comes in contact with the metallic heat sink, and conveying external air at ambient temperature inside the compressor chamber to enable reduction in operating temperature of the compressor chamber.
BRIEF DESCRIPTION OF DRAWINGS
[00022] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[00023] In the figures, similar components and/or features may have the same reference label. Further, various components of the same type may be distinguished by following the reference label with a second label that distinguishes among the similar components. If only the first reference label is used in the specification, the description is applicable to any one of the similar components having the same first reference label irrespective of the second reference label.
[00024] FIG. 1 illustrates an exemplary block diagram representation of a conventional inverter air conditioner;

[00025] FIG. 2 illustrates an exemplary block diagram representation of an
inverter air conditioner incorporating the proposed hybrid cooling system in
accordance with an embodiment of the present invention;
[00026] FIG. 3 illustrates an exemplary representation of arrangement of
components of the outdoor unit of the inverter air conditioner in accordance with an
embodiment of the present invention; and
[00027] FIG. 4 illustrates an exemplary flowchart representation of proposed
method for hybrid cooling of the outdoor unit of the inverter air conditioner in
accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
100028] If the specification states a component or feature "may", "can", "could", or "might" be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.
[00029] As used in the description herein and throughout the claims that follow, the meaning of "a," "an," and "the" includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of "in" includes "in" and "on" unless the context clearly dictates otherwise. [00030] Exemplary embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments are shown. This disclosure may however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. These embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the disclosure to those of ordinary skill in the art. Moreover, all statements herein reciting embodiments of the disclosure, as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure). [00031] Various terms as used herein are shown below. To the extent a term used in a claim is not defined below, it should be given the broadest definition persons in

the pertinent art have given that term as reflected in printed publications and issued patents at the time of filing.
[00032] The system for hybrid cooling of an outdoor unit of an inverter air conditioner may include an indoor unit, an outdoor unit and pipe arrangement connecting the indoor and outdoor units to complete the air-conditioning cycle. The outdoor unit of the inverter air conditioner includes a compressor chamber, at least one partition panel, a condensing unit and an inverter PCB (Printed Circuit Board). Further, the condensing unit may include a pipe, a condensing fan, an aluminium sink block, condenser coils, refrigerants or coolants flowing in the pipe and slots in the partition panel to allow the inflow of the ambient air inside the compressor chamber. The system provides hybrid cooling to the outdoor unit using two different cooling mediums, i.e., a refrigerant and external (ambient) air. [00033] The refrigerant in the pipe connected to the aluminium heat sink block and the PCB has a temperature of around 38 to 40 °C and it reduces the PCB temperature by 1 to 2 °C before expansion. Similarly, the ambient air entering at ambient temperature inside the compressor chamber reduces the temperature of the compressor by 1 to 2 °C even when the inverter air conditioner is working at low voltage of 195 Volts.
[00034] FIG. 1 illustrates an exemplary block diagram representation of a conventional inverter air conditioner. A typical air conditioner includes an indoor unit 102, an outdoor unit 104 and a pipe arrangement for completing air-conditioning cycle. The outdoor unit 104 of the air conditioner has a fan to blow out hot air from the outdoor unit 104 along with a compressor 106 and a condenser 108. With respect to the inverter air conditioner, main additional component is an inverter printer circuit board (PCB) 110 which is placed inside the outdoor unit 104. The inverter PCB 110 supports variable speed operation of the compressor which results in huge energy savings. The compressor through the pipe arrangement receives low pressure and low temperature refrigerant in vapour form from the indoor unit 102 of the air conditioner and converts it into high pressure and high temperature vapour for condensing. The condenser 108 of the air conditioner is a heat exchanger section having condenser 108 coils to cool down and condense the high temperature and high pressure vapour refrigerant flowing from the compressor. The indoor unit 102

has an evaporator which evaporates the condensed refrigerant liquid into cool air for cooling the room.
[00035] The conventional inverter air conditioner properly works up to a temperature of 50 °C. However, beyond this temperature, the components of the conventional inverter air conditioner, depending on their design, are operating at higher temperature than their respective threshold temperatures which ultimately leads to failure. In some instances, the inverter PCB 110 of the inverter air conditioner fails when the temperature of the PCB 110 components reaches beyond its design specification which happens at ambient temperature above 50 °C. Also, during such conditions, the compressor of the air conditioner works in overload condition and may trip while working at ambient temperature beyond 50 °C. The components fail because the temperature of the outdoor unit 104 is usually 3-5 °C above the ambient temperature.
|00036] The area around the compressor chamber 106 is at higher temperature due to poor air circulation inside compressor chamber 106. Similarly, heat emitted by the PCB 110 increases overall temperature of the outdoor unit 104 above the ambient temperature. Therefore, failing of components of the inverter air conditioner happens at 3-5 °C above the ambient temperature and not actually at the ambient working conditions of the mverter air conditioner. For example, if the temperature of the outside air is at 54 °C, then the temperature of the compressor chamber 106 will be around 60 °C and similarly, the PCB 110 will be at higher temperature. Thus, due to the heated surface of the compressor body, PCB 110 and poor air circulation, the overall temperature of the compressor chamber 106 of outdoor unit 104 increases. This results in the PCB 110 failing beyond the ambient temperature of 50 °C and the compressor tripping at such a temperature in longer term.
[00037] FIG. 2 illustrates an exemplary block diagram representation of an inverter air conditioner incorporating the proposed hybrid cooling system in accordance with an embodiment of the present invention. In an aspect, the inverter air conditioner of the present invention may include an indoor unit 202, an outdoor unit 204 and a pipe arrangement for completing the air-conditioning cycle. The

external air (also referred to as "ambient air" hereinafter) at ambient temperature inside the compressor chamber 206 and an inverter PCB 210. [00038] In an embodiment, the inverter PCB 210 may be attached internally at a top most portion of the outdoor unit 204. The PCB 210 supports variable speed operation of the compressor which results in huge energy savings. The compressor present inside the compressor chamber 206 receives low pressure and low temperature refrigerant through pipe arrangement from the indoor unit 202 of the air conditioner and converts it into high pressure and high temperature refrigerant. [00039] In an embodiment, the condensing unit 208 of the present invention is an advanced condensing unit 208. The condensing unit 208 may include a set of condensing coils and a heat exchanger operable to cool and condense the high pressure and high temperature refrigerant passing from outlet of the compressor chamber 206. The condensing unit 208 may also include an outlet pipe 212 to convey the cooled and condensed refrigerant to a metallic heat sink 212 in contact with the inverter PCB 210 such that during operation of the air conditioner the operating temperature of the inverter PCB 210 can be kept in check to prevent overheating and/or failure of the PCB components. In an embodiment, the condensing unit 208 may further include a condensing fan to blow out hot air from the outdoor unit 204 to an open space.
[00040] According to an embodiment of the present invention, the condensing fan of the condensing unit 208 along with the slots of the partition panel may allow external air which is at ambient temperature to flow inside the compressor chamber 206 and cool the compressor chamber 206. The ambient air flowing inside the compressor chamber 206 can reduce the temperature of the compressor, operating beyond the ambient temperature, by 1 to 2 °C, thereby preventing overheating as well as failure of components in the compressor chamber 206. During working of the compressor, temperature of the compressor chamber 206 may rise up to 40 °C whereas the ambient temperature may be at 35 °C. Therefore, intake of the external air blowing at 35 °C from the slots of the partition panel cools the compressor and reduces the temperature of the compressor chamber 206 by a factor ringing from 1 to 2°C.

[00041] According to an embodiment of the present invention, the outlet pipe 212 of the condensing unit 208 carrying the refrigerant may be extended to contact the aluminium heat sink 214 that is in contact with the inverter PCB 210. Hence, the aluminium heat sink 214 acts as an intermediate component between the outlet pipe 212 and the PCB 210 for heat exchange. The outlet pipe 212 of the condensing unit 208 may be a liquid line that has a refrigerant flowing at temperature of 38 to 40 °C when ambient temperature is 35 °C. During working of the PCB 210, temperature of the PCB components may rise up to 70 °C or beyond and the condensing unit 208 of the present invention may reduce the temperature of the PCB components by 1 to 2 °C before expansion.
[00042] In an embodiment, the aluminium heat sink 214 used as the intermediate component may have a preferred dimension of 50 mm X 168 mm, and length for outlet pipe 212 in contact with aluminium heat sink 214 may be between 320 mm to 400 mm. It would be appreciated by a person skilled in the art that the dimensions of the heat sink and the outlet pipe mentioned above are exemplary, and modifications and/or alterations may be made in the dimensions of the heat sink and the outlet pipe depending on their design characteristics and application within departing from the scope of the invention, and any such modification or alteration is well within the scope of the present invention.
[00043] In an embodiment, the hybrid cooling of the outdoor unit 204 of the air conditioner with two different mediums, i.e., air and refrigerant, provided in the condensing unit 208 improves efficiency of the air conditioner by reducing temperature of both the compressor chamber 206 and the inverter PCB 210 of the outdoor unit 204 of the air conditioner. The hybrid cooling for PCB 210 reduces temperature of the compressor chamber 206 and the inverter PCB 210 components by approximately 1 to 2 °C and improves working characteristics of the compressor in comparison to conventional air conditioners by reducing temperature of the compressor chamber 206 by a factor ranging from 1 to 2 °C.
[00044] According to an embodiment of the present invention, the hybrid cooling of the air conditioner enhances overall efficiency of the air conditioner and delivers results including high ambient working at 55 °C even when the inverter air conditioner is working at low voltage of 195 Volts.

[00045] FIG. 3 illustrates an exemplary representation of arrangement of components of the outdoor unit of the inverter air conditioner in accordance with an embodiment of the present invention. The inverter PCB 210 is arranged internally at the top most part of the outdoor unit 204. The outlet pipe 212 from the condensing unit 208 carrying the refrigerant is connected to the inverter PCB 210 through an intermediate component, i.e., the aluminium heat sink block 214 acting as a heat exchanger. Further, the intake of the external air is provided through vent arrangement mounted at the front surface of the outdoor unit 104 on the same plane where the condensing fan is mounted. The external air is drawn-in through the air-vent and the slots in the partition panel to the compressor chamber 206 for cooling the compressor. The condensing fan draws out the hot air from the compressor chamber 206 of outdoor unit 204 of the inverter air conditioner to reduce heat collected in the outdoor unit 204 of the inverter air conditioner. [00046] In an embodiment, the condensed refrigerant after passing through the aluminium heat sink 214 may flow into the indoor unit 202 for expansion and recirculation.
[00047] FIG. 4 illustrates an exemplary flowchart representation of proposed method for hybrid cooling of outdoor unit of the inverter air conditioner in accordance with an embodiment of the present invention. The method includes, at step 402, receiving low pressure and low temperature refrigerant from an indoor unit of the inverter air conditioner and converting the low pressure and low temperature refrigerant into high pressure and high temperature refrigerant by a compressor chamber. The method further includes, at step 404, condensing the high pressure and high temperature refrigerant, and at step 406, conveying the condensed refrigerant to a metallic heat sink in contact with an inverter PCB of the outdoor unit to enable reduction in operating temperature of the PCB when the condensed refrigerant comes in contact with the metallic heat sink. At step 408, external air at ambient temperature is conveyed inside the compressor chamber through at least one partition panel comprising a plurality of slots, to enable reduction in operating temperature of the compressor chamber.
[00(148] Thus, the present invention relates to a system and method for hybrid cooling of an outdoor unit of an inverter air conditioner that includes a compressor

chamber for converting low pressure and low temperature refrigerant into high pressure and high temperature refrigerant, a condensing unit for condensing the high pressure and high temperature refrigerant, said condensing unit comprising an outlet pipe to convey the condensed refrigerant to an aluminium heat sink in contact with an inverter PCB of the outdoor unit, and at least one partition panel comprising slots to allow ingress of external air at ambient temperature inside the compressor chamber. When condensed refrigerant comes in contact with the aluminium heat sink operating temperature of the PCB is reduced. Flow of the external air at ambient temperature inside the compressor chamber enables reduction in operating temperature of the compressor chamber.
[00049] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. "such as") provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[00050] While embodiments of the present disclosure have been illustrated and described, it will be clear that the disclosure is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions, and equivalents will be apparent to those skilled in the art, without departing from the scope of the disclosure, as described in the claims.

We Claim:
1. A system for hybrid cooling of an outdoor unit (204) of an inverter air
conditioner, the system comprising:
a compressor chamber (206) for receiving low pressure and low temperature refrigerant from an indoor unit (202) of the inverter air conditioner and converting the low pressure and low temperature refrigerant into high pressure and high temperature refrigerant;
a condensing unit (208) for condensing the high pressure and high temperature refrigerant, said condensing unit (208) comprising an outlet pipe (212) to convey the condensed refrigerant to a metallic heat sink (214) in contact with an inverter printed circuit board (PCB) (210) of the outdoor unit (204); and
at least one partition panel comprising a plurality of slots to allow ingress of external air at ambient temperature inside the compressor chamber (206),
wherein when the condensed refrigerant comes in contact with the metallic heat sink (214) that is in contact with the inverter PCB (210), operating temperature of the PCB (210) is reduced, and
wherein flow of the external air at ambient temperature inside the compressor chamber (206) enables reduction in operating temperature of the compressor chamber (206).
2. The system as claimed in claim 1, wherein flow of the external air at ambient
temperature flowing inside the compressor chamber (206) allows reduction in
operating temperature of the compressor chamber (206) by a factor ranging from 1
°C to 2 °C.
3. The system as claimed in claim 1, wherein when the condensed refrigerant
comes in contact with the metallic heat sink (214), operating temperature of the
inverter PCB (210) is reduced by a factor ranging from 1 °C to 2 °C.

5. The system as claimed in claim 1, wherein the inverter PCB (210) is arranged internally at a top portion of the outdoor unit (204).
6. The system as claimed in claim 1, wherein the condensing unit (208) comprises a condensing fan for drawing out hot air from the compressor chamber (206) into an open space.
7. The system as claimed in claim 1, wherein the external air at ambient temperature is drawn into the combustion chamber (206) through a vent arrangement and the plurality of slots of the at least one partition panel.
8. The system as claimed in claim 1, wherein the condensed refrigerant after passing through the metallic heat sink (214) flows into the indoor unit (202) for expansion and recirculation.
9. The system as claimed in claim 1, wherein dimension of the metallic heat sink (214) is 50 mm X 168 mm.
10. The system as claimed in claim I, wherein length of the outlet pipe (212) is in the range of 320 mm to 400 mm.
11. A method for hybrid cooling of an outdoor unit (204) of an inverter air conditioner, the method comprising the steps of:
receiving low pressure and low temperature refrigerant from an indoor unit (202) of the inverter air conditioner and converting the low pressure and low temperature refrigerant into high pressure and high temperature refrigerant by a compressor chamber (206);
condensing the high pressure and high temperature refrigerant;
conveying the condensed refrigerant to a metallic heat sink (214) in contact with an inverter printed circuit board (PCB) (210) of the outdoor unit (204) to enable reduction in operating temperature of the PCB (210) when the condensed refrigerant comes hi contact with the metallic heat sink (214); and

conveying external air at ambient temperature inside the compressor chamber (206) to enable reduction in operating temperature of the compressor chamber (206).