1. TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to air- conditioning apparatus using an all aluminum heat exchanger assembly and more particularly to provide a corrosion resistance structure in order to prevent galvanic corrosion of the aluminum heat exchanger assembly when it is installed and mounted in . contact with the less reactive metal components of the air- conditioning apparatus .

2. BACKGROUND OF THE INVENTION

Air-conditioning apparatuses are known in the art. Air-conditioner generally functioned to transport heat from inside to the outside using refrigerant as the heat transferring means. The refrigerant traditionally includes Freon or, currently the more environmental-friendly CFC-free refrigerant. The process involves three major components i.e., a compressor, an outdoor heat exchanger (also known as a condenser in cooling mode) , an indoor heat exchanger (also known as an evaporator in cooling mode) and an expansionary device such as capillary tube. The compressor and the outdoor heat exchanger are usually equipped in the outdoor unit.

The initial structure and behavior of a fundamental refrigerant cycle is hereby described. The refrigerant arrives at the compressor as a cool, low-pressure gas. Then the compressor compresses the refrigerant, so that their enthalpy and pressure increase. The refrigerant leaves the compressor as a hot, high pressure gas and flows into the condenser. The condenser has metal fins that assist the refrigerant in transferring heat to the surrounding outdoor air. As this transfer takes place, releasing additional thermal energy into the surrounding air and causing the refrigerant to transform into a liquid or almost, liquid.

This high-pressure liquid then flows into the evaporator through an expansion device.. . This expansion device allows the liquid's pressure to drop while keeping its enthalpy. As it evaporates, it absorbs heat from the air around the evaporator and changes its phase from liquid into gas. The evaporator also has metal fins to assist it in exchanging thermal energy with the surrounding air. By the time the refrigerant leaves the evaporator, it becomes a cool, low pressure gas. It then returns to the compressor to begin its circulation all over again. In general, the refrigerant releases heat into the outside air and absorbs heat from the inside air. The process is further assisted by the presence of a fan arranged corresponding with a heat exchanger in the outdoor unit and in the indoor unit .

In an air-conditioning, apparatus , the heat exchanger assembly is one of the key components ensuring its proper operation. As mentioned earlier, the heat exchanger assembly typically includes a multiplicity of fins along with headers and plates to help in transferring heat to the surrounding outdoor air. There are various types of heat exchanger arrangements known in the art including the tubes with thin fins, microchannel with flat metal fins, microchannel flat tubes with fins and others. Typical heat exchangers structure are made from a combination of one or more refrigerant carrying copper tubes laced through a plurality of relatively thin aluminum fins . The copper tubes extend between steel inlet and outlet endplates and the heat exchanger is mounted by attaching steel endplates to the steel cabinet of the outdoor unit. However, this known arrangement of heat exchanger assembly is not without its inherent disadvantages. For example, the two separate materials forming the heat exchanger structure poses manufacturing difficulty. Further, the high cost of copper also adds. to the manufacturing cost. It is therefore preferred that an all aluminum heat exchanger assembly is developed for use in an air-conditioning apparatus.

In this respect, an all aluminum heat exchanger assembly offers advantages in term of cost, lower weight and better heat transfer. In term of cost, aluminum remains one of the most cost-effective materials known. In term of performance, aluminum improves system weight significantly. However, if the aluminum structure is in contact with less reactive material for example, the typical steel casing of the air-conditioning apparatus, galvanic corrosion occurs and would generally poses problems for the all aluminum heat exchanger assembly. Such problems include reduced performance of the outdoor unit as well as reduced life span of the all aluminum heat exchanger assembly. Nevertheless, due to the specific material properties, aluminum lasts longer than other materials when used in an appropriate way. Further, aluminum is also having advantage due to the easy forming abilities in the manufacturing process. To overcome the above problems associated, with reactive or galvanic corrosion of the dissimilar contacting materials, suitable isolation structure must be _. arranged between the steel casing and the all aluminum heat exchanger assembly. Such a structure could be used to secure the heat exchanger assembly to the casing as well as preventing galvanic corrosion of the all aluminum heat exchanger .

The present invention proposes a solution to the prior outdoor unit of an air-conditioning apparatus. In particular, it is proposed that a non-metal holder or mounting bracket is used to mount the heat exchanger assembly to the steel casing of the air- conditioning apparatus, the non-metal holder/mounting bracket also functioned as an isolation structure to prevent the all aluminum heat exchanger assembly from being physically in contact with the steel casing.

Preferably, the heat exchanger assembly is secured to the non-metal holder or mounting bracket and thereafter to the steel plate of the casing by way of an easy slid and locked engagement. Such slid and locked arrangement offers convenient assembly of the air-conditioning apparatus. Also preferable, the non-metal holder/mounting bracket is made of resin or other insulative materials . 3. SUMMARY OF THE INVENTION

It is an object of the present invention to provide a reliable and dependable all aluminum heat- exchanger assembly for use in air-conditioning apparatus which has isolation structure in used for the mounting of the heat exchanger assembly. The isolation structure functions as corrosion resistance structure to prevent galvanic corrosion caused by reactive action between . contacting- dissimilar materials forming the heat exchanger and the steel casing of the air-conditioning apparatus. The isolation structure is configured as a non-metal holder or mounting bracket used for fixing the heat exchanger assembly to the steel plate of the air- conditioning outdoor unit casing.

It is another object of the present invention to provide an easy to use mounting bracket to secure the heat exchanger to the casing through a slid and snap-fit arrangement .

These and other objects of the present invention are accomplished by providing,

A mounting bracket (1) adapted to secure a heat exchanger assembly (2) of an air-conditioning apparatus (3) to within an internal casing of said air-conditioning apparatus, characterized in that said mounting bracket (1) comprises of: a body (4) provided therein with a retaining channel (5) having a closed end section (6) , said retaining channel (5) is adapted to receive at least a header (9) of said heat exchanger assembly (2); a fastener boss (7) integrally formed with said body (4), said fastener boss (7) is adapted to receive a fastener to securely mount said mounting bracket to the internal casing of said air-conditioning apparatus thus securing said; heat exchanger assembly (2) to the same; and said mounting bracket (1) is made of resin, plastic and other insulative material to prevent galvanic corrosion of the heat exchanger assembly (2) .

It is preferable that slots and opening are formed on the mounting bracket body, the slots are adapted to engage with, the plate of the heat exchanger assembly to further secure it in position and the opening is formed to provide water drain to flow through .

It is also preferable that at least one fastener boss is integrally formed with the body of the mounting bracket. More preferably, two of such fastener boss is integrally formed with the body of the mounting bracket.

And it is also preferable that the retaining channel is formed slightly bigger that the cross-section of the heat exchanger header, such bigger cross-section formed clearance between the header and the. retaining channel for mitigating of expansion of the heat exchanger assembly when in operation. It is also preferable that four of the same mounting ^' brackets are used for securing the heat exchanger assembly in position, each of the mounting brackets is located on each corner of the generally rectangular heat exchanger assembly.

It is also preferable that only one type of such mounting bracket is made available for ease of : manufacturing and storage in the assembling process of the air-conditioning apparatus. 4. BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures in which:

Figures la and lb show an exploded view of an outdoor unit of an air-conditioning apparatus configured according to the preferred embodiment of the present invention of which the figure shows some components, of the outdoor unit in unassembled state.

Figure 2 shows perspective view of a mounting bracket used to secure an all aluminum heat exchanger assembly of the present invention.

Figure 3 shows perspective partial view of the installed mounting bracket together with the all aluminum heat exchanger assembly of the present invention, the mounting bracket is fixed at the upper portion of the heat exchanger assembly. Figure 4 shows perspective partial view of the installed mounting bracket together with the all aluminum heat exchanger assembly of the present invention, the. mounting bracket is fixed at the lower portion of the heat exchanger assembly.

Figure 5 shows another perspective view of the mounting bracket configured . according. to the embodiment of the present invention.

Figure 6 shows a combination of upper and lower mounting bracket located in position and assembled accordingly forming part structure of an outdoor unit of the present invention.

Figure 7 shows cross-sectional view of the mounting bracket configured according to the preferred embodiment of the present invention.

5. DETAILED DESCRIPTION OF THE DRAWINGS

As mentioned earlier and with reference to Figure la and lb of Figure 1, the typical split- type air- conditioning apparatus generally includes an indoor unit (not shown) and an outdoor unit (3). Installed within the outdoor unit's main casing (12) are fan (13), compressor (not shown) , condenser or heat exchanger assembly (2) and a control box (not shown) . In all air-conditioner apparatuses, the operation is controlled through the control box (not shown) . Various electronic components are arranged on the control board (also not shown) of the control box to ensure that the air-conditioner operates as intended. An end-plate (14) is used to isolate the compressor and the control box together with the related electronic components from the heat exchanger assembly (2) to within the respective internal compartment of the outdoor unit.

The heat exchanger assembly (2) is preferably made of all aluminum material due to the advantages of the generally corrosion-resistant characteristic of aluminum, lower weight as well as better heat transferring performance. However, and as mentioned earlier, the all aluminum heat exchanger assembly may suffer from galvanic corrosion if the all aluminum heat exchanger assembly is physically in contact with other less reactive material it may comes in contact with. As a example, the casing of the outdoor unit is typically made of steel and steel being less reactive than aluminum causes the aluminum to be exposed to galvanic corrosion process. An isolator device in the form of plastic, resin or other insulative mounting bracket (1) is preferably used to secure the all aluminum heat exchanger assembly (2) to the internal casing of the steel cabinet. Such mounting bracket (1) is preferably arranged on each corner of the generally rectangular heat exchanger assembly (2) as shown in Figure 1.

As a result of this advantageous mounting bracket structure, the heat exchanger assembly is reactively isolated from the steel cabinet thus preventing galvanic corrosion due to the otherwise contacting element. The specific configuration of the mounting bracket (1) is shown in Figure 2. Figure 2 shows perspective view of the mounting bracket of the present invention. Preferably, only one type of such mounting bracket is made available but it is provided with suitable structural, configuration that could still be used on each corner of the rectangular heat exchanger. This is particularly to ensure that the manufacturing process of the bracket is simplified as well as for convenient of storage of the bracket in the assembling of the air-conditioning apparatus because only a single type of the mounting bracket is preferable.

Still referring to Figure 2, the mounting bracket (1) is shown comprises of a generally cylindrical body (4) with a retaining channel (5) and having a generally closed end section (6), the retaining channel (5) is formed to receive the header (9, Figure 3) of the heat exchanger assembly (2), a fastener boss (7) integrally formed with the cylindrical body (4) . Preferably, two of such fastener bosses are formed on the cylindrical body, such detail is more clearly shown in Figure 5. The fastener boss (7) is adapted to receive a fastener, for example screw (not shown) to securely mount the mounting bracket to the internal casing of the air- conditioning apparatus thus securing the heat exchanger assembly (2) to the casing of the outdoor unit. The mounting bracket (1) is preferably made of resin, plastic and other insulative material. Such a material formed isolation barrier between the all aluminum heat exchanger assembly and the steel casing or cabinet thus preventing a possible galvanic corrosion to the heat exchanger assembly ( 2 .

Still referring to Figure 2, slots (8) are formed at the side of the closed end section (6). and such slots (8) are adapted to receive the top plate (10, Figure 3) of the heat exchanger assembly (2) . In effect, the header (9,. Figure 3) and top plate (10, Figure 3) and the bottom plate (15, Figure 4) of the heat exchanger could be secured to the mounting bracket in order to have a particularly strong mounting arrangement . Also preferable, the generally closed end section of the cylindrical body (4) is provided with a small opening (11) to allow drainage of water or fluid from being, accumulated in the mounting bracket .

Now referring to Figure 3 , where the figure shows perspective partial view of the installed mounting bracket (1) shown together with the all aluminum heat exchanger assembly (2) where the mounting bracket is fixed at the upper portion of the heat exchanger assembly. In this position, the mounting bracket (1) of Figure 1 is inverted thus exposing the generally closed end (6) with the drain opening (11) located at the end portion. To secure the heat exchanger component into the mounting bracket, the header (9) of the heat exchanger assembly is first slid into the retaining channel (5, Figure 2) and thereafter retained by the closed end section (6). In the meantime, the top plate (10) of the heat exchanger assembly is also secured in position between the two side slots (8). A screw (not shown) is then inserted into the fastener boss (7) and fasten further to fix the bracket onto the casing (3) . It should be noted here that the. left and right brackets of the upper position should have the same arrangement as hereinfor described. However, due to the specific mounting requirement especially with regard to clearance between the components, the location of the boss may be at different position as. required.

Now referring to Figure 4, where the figure, shows perspective partial view of the installed mounting bracket together with the all ^' aluminum heat exchanger assembly of the present . invention, the mounting bracket (1) is fixed at the lower portion of the heat exchanger assembly. In this position, the generally closed end section of the cylindrical body (4) is positioned at the bottom. The retaining channel (5, Figure 2) retained the heat exchanger header (2) and the slots (8) retained the bottom plate (15) of the heat exchanger assembly. Although the header is secured within the retaining channel (5) through a slid and snap-fit arrangement,, preferably there is provided clearance between the header and the internal structure of the .retaining channel (5) , the clearance is provided to cater for possible expansion of the heat exchanger assembly, especially the headers during the operation of the air-conditioning apparatus.

Figure 5 shows another perspective view of the mounting bracket (1) configured according to the embodiment of the present invention. As shown in this figure, the mounting bracket is formed- having two of such fastener bosses (7) whereby the fastener boss is to be used to fix a screw into the respective side of the air-conditioning apparatus casing thus securing the heat exchanger in position within the internal casing of the outdoor unit. Such a structure allows the application of a single type mounting bracket for use on every position it is located. As also mentioned earlier, the ^' mounting bracket (1) is preferably made of resin, plastic or other insulative materials.

Now referring to Figure 6 where the figure shows a combination of upper and lower mounting bracket located in position and assembled accordingly to form part structure of an outdoor unit of the present invention. Besides being used to secure the mounting of the all aluminum heat exchanger assembly (2) within the internal casing of the outdoor unit, the mounting bracket (1) also operates as isolation device to prevent contact between two dissimilar metal structure of the heat exchanger assembly and the casing. Such isolation device is believed to be able to prevent galvanic corrosion to the all aluminum heat exchanger assembly as well as means to mount the heat exchanger assembly in position. The drain opening (11) advantageously prevents water from being accumulated within the internal structure- of the cylindrical body of the mounting . bracket . As generally known in the art, water is an electrolyte capable of allowing electron transfer through it. If water is presence between the all aluminum heat exchanger assembly and the steel casing, galvanic corrosion may occur. Therefore by having such an opening, water could be drained out thus preventing water accumulation. With mounting bracket for an all aluminum heat exchanger assembly being provided through the embodiment of the present invention, problem of galvanic corrosion due to contacting dissimilar metallic material is effectively avoided.

Figure 7 shows cross-sectional view of the preferred embodiment of the mounting bracket. In particular, the internal surface of the retaining channel (5) of the mounting bracket (1) is formed having plurality of protrusion (16) that extends along the length of the retaining channel, such feature allows minimum contact between the header (9) and the mounting bracket (1) but yet provides secure mounting of the header to the mounting bracket through the preferred snap-fit contact. Such minimum contact advantageously causes less heat transfer to the mounting bracket thus the mounting bracket has less heat deformation. The minimum contact surface also causes less friction between the contacting surfaces and this will lead to easy assembling process of the outdoor unit. Further, clearance (17) between the header (9) and the internal surface of the retaining channel (5) allows water, fluid and other liquid to flow through. Such clearance is preferably set at about 0.5 ± 0.3 mm where the diameter of the header (9) is approximately 18 mm. Such protrusion (16) could advantageously be formed as linear protrusion that extends along the length of the retaining channel (5) , plurality of noncontiguous protrusions arranged equally spaced apart from each other, plurality of noncontiguous protrusion arranged randomly or in any other suitable configuration.

Although the present invention is generally intended for use in a split-type air-conditioning apparatus, the features of the all aluminum heat exchanger assembly including the mounting bracket could also be incorporated into a window-type air-conditioning apparatus without requiring substantial modification to the mounting bracket. Such flexibility also offers more functionality to the present invention.

With the preferred embodiment . of the present invention being implemented, heat generated by the operation of the air-conditioning apparatus is advantageously mitigated thus allowing the apparatus to be used in any weather condition especially in the extreme weather countries . While, the preferred embodiments of the present invention have been described, it should be understood that various changes, adaptations and modifications may be made thereto. It should be understood, therefore, that the invention is not limited to details of the illustrated invention shown in the figures and that variations in such minor details will be apparent to one skilled in the art.