1. TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to air- conditioning apparatus and more particularly to outdoor unit of an air-conditioning apparatus, the outdoor unit being provided with separate chamber for the all aluminum heat exchanger together with the fan assembly and another chamber for the compressor and the related components, the chambers being separated by partition plate and an end plate fixed onto it and to prevent water from entering the compressor chamber. The present invention also relates to a clip holder used to secure the all aluminum tube header of the heat exchanger assembly to the end plate, the clip holder also used to isolate them reactively.

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.

Critical to ensure the proper operation of the air- conditioning apparatus is the outdoor unit that houses the compressor, heat exchanger assembly, expansion device, accumulator and the related electrical/electronic control components. Typically, the housing of the outdoor unit is compartmentalized by partition plates to separate them into chambers, i.e., chamber for the heat exchanger and blower fan (also known as heat exchanger chamber) and chamber for the compressor, electrical/electronic components, control box and the accumulator (also known as machine chamber) .

Typical in the known outdoor unit assembly, the partition plates are made of steel. Further, in the typical outdoor unit, the heat exchanger is typically consists of multiplicity of fins along with headers and plates to help in transferring heat to the surrounding outdoor air. The 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 headers and the heat exchanger is mounted by attaching steel headers to the steel cabinet of the outdoor unit. However, this known arrangement of heat exchanger assembly is not without its inherent disadvantage. For example, the two different 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, weight and better heat transfer compared to most metals. In term of cost, aluminum remains one of the most cost- effective materials known. In term of performance, aluminum improves system weight significantly. Further in itself, aluminum is a highly corrosion- resistant material. However, if the aluminum structure is in contact with less reactive material for example, the typical steel of the air- conditioning casing including the partition plates, galvanic corrosion occurs and would generally poses a problem for the all aluminum heat exchanger assembly. Such a problem includes 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 environment. Further, aluminum is also having advantage due to the easy forming abilities in the manufacturing process.

As mentioned earlier, the outdoor unit of an air- conditioning apparatus is typically provided with separate chamber for the all aluminum heat exchanger together with the fan assembly and another chamber for the compressor and the related components whereby the chambers are being separated by partition plate and end plate. The end plate is fixed to the partition plate between the air flow chamber and the compressor chamber. The end plate is also being provided with openings for allowing tube header of a heat exchanger assembly to pass through it. As the end plate is made of steel whereas the heat exchanger is made of aluminum, an isolation structure in the form of clip holder is arranged to secure the tube header to the opening in the end plate as well as the isolation structure.

An all aluminum heat exchanger has aluminum inlet and outlet tubes extending through the partition plates for connection with the compressor via the corresponding inlet and outlet ports. As mentioned earlier, if aluminum is put in contact with any less reactive material especially steel, galvanic corrosion occurs to the aluminum. Therefore, it is necessary to isolate the aluminum inlet and outlet headers from being in contact with the partition plate, especially the end plate when the outdoor unit has been assembled, installed and in operation. This is to overcome problems associated with reactive or galvanic corrosion of the dissimilar contacting materials. The present invention proposes a solution to retain and isolate the aluminum inlet and outlet tubes of the heat exchanger from being in contact with steel end plate of the outdoor unit. In particular, it is proposed that a non-metal clip holder is used to retain the headers in position on the end plate as well as providing isolation structure to prevent the all aluminum headers from contacting the steel end plate directly. Apart from providing secure mounting as well as an isolation structure, the end plate is also used to prevent water from entering the machine chamber. Such water prevention structure advantageously prevents water invasion _ to life parts in the machine chamber which may cause short circuit of the electronic circuit. Further, the inlet and outlet tubes of the heat exchanger are preferably formed to have a short bend before connection to the tube port of compressor and 2,3 way valve. Such a short bend is preferred for purpose of reducing or limiting physical stress to the all aluminum heat exchanger assembly, particularly due to vibration when the unit is in operation. Preferably, the clip holder is configured in two types, a first clip holder type and a second clip holder type, the selection of which is to use is a subject to where the clip holder is to be positioned on the end plate. The clip holder is secured to the tube headers and put into position on the end plate through a convenient slot-in arrangement. Also preferable, the clip holder is made of resin or other suitable insulative materials.

3. SUMMARY OF THE INVENTION It is therefore 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 to the steel casing, especially the mounting of the inlet and outlet tubes of the heat exchanger through the end plate of the outdoor unit.

In this respect, the isolation structure functioned as corrosion resistance structure to prevent galvanic corrosion caused by reactive action between dissimilar contacting materials that form the heat exchanger assembly and the steel end plate of the air-conditioning apparatus as well as a securing structure of the heat exchanger inlet and outlet tubes to the end plate. The isolation structure is configured as a clip holder made of resin, plastic or other insulative materials and used for fixing the heat exchanger tube header to the steel end plate of the outdoor unit. It is another object of the present invention to provide an easy to use clip holder to secure the heat exchanger inlet and outlet tubes to the end plate through a snap-fit arrangement.

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

An outdoor unit (3) of an air-conditioning apparatus, said outdoor unit having an all aluminum heat exchanger assembly (2) and compressor assembly (23) individually retained in separate chambers, said chambers being separated by a partition plate

(15) and an end plate (14) fixed onto said partition plate (15), said all aluminum heat exchanger assembly (2) having inlet (16) and outlet (17) tubes and said end plate (14) having tube inserting portion (19,20) to receive said inlet and outlet tubes (16,17), characterized in that: a clip holder (1) is inserted into said tube inserting portion (19, 20) to securely retain said inlet (16) and outlet (17) tubes to said end plate (14) . It is preferable that the clip holder (1) comprises of a flat portion (4) provided therein with a retaining channel (5) formed across the flat portion, the retaining channel (5) having profile that matches with the profile of the tube header

(24) of the heat exchanger assembly (2), a guide portion (6) formed substantially at right angle to the longitudinal direction of the retaining channel (5) , and the guide portion (6) intersect with the retaining channel (5) and forming an opening (7) thereat .

It is preferable that the retaining channel (5) is formed as a half-cylindrical body that matches with the profile of the heat exchanger header.

It is also preferable that the guide portion of the clip holder is formed as a generally C-shaped opening profile.

And it is also preferable that the guide portion of the clip holder is also formed as a cylindrical body with slit formed along the length of the cylindrical wall .

It is also preferable that the clip holder is formed in two types of profile structure, the first type is used for securing the inlet tube through the upper opening formed on the end plate and the second type for securing the outlet tube through the lower hole of the end plate.

It is also preferable that the tubes are bent immediately after exiting through the openings on the end plate. Such immediate and short bent allow reduction of physical stress exerted to the all aluminum heat exchanger assembly, particularly due to vibration when the unit is in operation. And it is also preferable that the clip holder is made of resin, plastic or other insulative materials .

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:

Figure 1 shows perspective view of unfinished assembly of outdoor unit of an air-conditioning apparatus configured according to the preferred embodiment of the present invention.

Figure 2 shows perspective view of the outdoor unit of Figure 1 shown in unassembled state.

Figure 3 shows exploded perspective view of the outdoor unit showing the relative position of the end plate that separates the outdoor unit chambers and components residing in the machine chamber.

Figure 4 shows another exploded perspective views of the outdoor unit as illustrated in Figure 3.

Figure 5 shows perspective view of clip holder used to secure an all aluminum heat exchanger inlet and outlet tubes to the end plate of the present invention .

Figure 6 shows steps to secure the inlet and outlet tubes of the heat exchanger to the end plate according to the present invention. 5. DETAILED DESCRIPTION OF THE DRAWINGS

As mentioned earlier and with reference to Figure 1 and Figure 2, 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 (23) , condenser or heat exchanger assembly (2) and a control box (not shown) . An end plate (14) together with partition plate (15) are used to isolate the compressor together with the related components from the heat exchanger assembly

(2) chamber to within the respective internal compartment or chamber of the outdoor unit.

The heat exchanger assembly (2) is preferably made of an all aluminum material due to the advantages of the generally the lower weight as well as low cost.

However and as mentioned earlier, the all aluminum heat exchanger assembly suffers from galvanic corrosion if the all aluminum assembly is in contact with other less reactive material. For 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. In this respect, the heat exchanger assembly (2) is normally provided having tube header disposed on the upper (16) and lower (17) positions on the heat exchanger assembly as inlet and outlet tubes for the refrigerant to flow in and out of the heat exchanger. Specifically, these inlet and outlet tubes (16, 17) are used for connection to 2, 3 valve (21, Figure 3) and port

(18) of the compressor (23, Figure 1). The tubes are connected through the respective inlet and outlet ports upon exiting from tube inserting portion (19, 20, Figure 2) of the end plate (14) . Preferably, the upper opening (19) is formed as a C-shaped opening (more clearly seen in Figure 5) whereas the lower opening (20) is formed as circular opening. Although the preferred tube inserting portion (19, 20) is shaped and located as shown in the figure, various other configurations could also be implemented. For example, the tube insertion portion could be both formed as C-shaped opening, or both could be formed as circular hole where the position could be in the same general vertical line or in the alternate left or right position.

In this respect, an isolator device in the form of plastic, resin or other insulative clip holder (1, Figure 5) is preferably used to secure the all aluminum heat exchanger assembly, particularly the inlet and outlet tubes (16, 17) of the heat exchanger through the steel end plate (14) . Such clip holder (1) is preferably secured on each tube inserting portion (19, 20) of the end plate (14) for use by the respective inlet (16) or outlet tube (17) . Apart from providing secure mounting of tube headers, the clip holder also acts as isolation device to prevent galvanic corrosion of the tube headers as well as preventing rain water from entering the machine chamber through the tube inserting portion (19, 20) as the clip holder also acts as seal on the openings. The specific configuration of the clip holder (1) is shown in Figure 5.

Figure 2 shows another perspective view of the outdoor unit of Figure 1 but in unassembled state. In this figure, the outdoor unit includes the outdoor unit's base pan (22), fan (13), compressor (23, Figure 1), condenser or heat exchanger assembly (2), partition plate (15, Figure 1) and the end plate (14) . As also shown in the figure, the inlet and outlet tubes (16, 17) of the heat exchanger (2) that are formed having short bent profile.

Figures 3 and 4 show further perspective views of the outdoor unit showing in greater details arrangement realized in the machine chamber of the indoor unit. The all aluminum inlet tube (16) passes through the upper opening (19, Figure 2) of the tube inserting portion on the end plate (14) to the compressor port (18) and the outlet tube (17) passes through the lower opening (20) of the end plate (14) then to the 2, 3 way valve (21) for a complete refrigerant circuit. In one of the preferred function, the clip holder (1) provides secure mounting of the tube headers onto the end plate (14) . The inlet and outlet tubes are preferably having curving or bending formation as shown in the Figures 3 and 4. The clip holder also acts as sealing arrangement to close any gap formed between the headers and the openings when installed in place . Figure 5 shows perspective view of the clip holders that are used to secure the all aluminum heat exchanger tube header to the end plate of the present invention. In particular, the clip holder is preferably made into two types, the first type (la) for mounting the tube header on the upper opening (19) and the second type (lb) for mounting the tube header on the lower hole (20) . As shown in the figure, the clip holder (1) includes a flat portion

(4) provided therein with a retaining channel (5) formed across the flat body, the retaining channel

(5) having profile that matches with the profile of the tube header (24, Figure 2), a guide portion (6) formed substantially at right angle to the longitudinal direction of the retaining channel (5) wherein the guide portion (6) intersects with the retaining channel (5) forming an opening (7) thereat. The guide portion (6) is preferable formed as a first type with C-opening profile or a second type with cylindrical wall having a slit (8) . Preferably the retaining channel (5) of the flat portion (4) is formed as a half-cylindrical body having opening (7) formed through it.

Still referring to Figure 5, for the first option where the clip holder is to be inserted into the upper opening (19) of the end plate (14) , a first type clip holder (la) is provided having the guide portion (6) together with the opening (7) forming the generally C-shaped opening profile, preferably with a more than 180° circular angle. On the other hand, the second type clip holder (lb) is provided where the guide portion (6) is formed having cylindrical wall with the slit (8) formed along the length of the cylindrical wall for insertion into the lower hole (20) of the end plate (14) .

The inlet and outlet tubes (16, 17, Figure 2) is to be inserted through the tube inserting portion (19,

20) formed on the end plate (14) and held in position by the clip holder (1) . The clip holder (1) is preferably made of resin, plastic and other insulative materials. The application of insulative clip holder (1) advantageously prevents galvanic corrosion to the all aluminum heat exchanger assembly (2) from occurring due to contact of dissimilar metallic materials of the aluminum header of the aluminum heat exchanger assembly with the steel end plate as well as preventing water from entering into the machine chamber.

Still referring to Figure 5, the upper clip holder (la) is easily secured to the upper opening (19) by simply sliding the inserting piece (6) through the opening. The lower clip holder (lb) is also conveniently locked in position in the lower hole (20) by simply pushing the inserting piece (6) through the lower hole (20) of the end plate. The insertion is further help by having the cylindrical wall of the guide portion (6) formed with the slit

(8) allowing it to slightly deform to match with the circular hole (20) dimension.

Figure 6 shows sequences of installing the end plate (14) to the required position. The inlet and outlet tubes (16, 17) must be first provided with the required clip holder (1) secured on it. The lower clip holder (lb) is then inserted into the lower opening (20) and thereafter the end plate is raised to an upright position as in Figure 6c. As the upper opening (19) is of the open- type (or C-shaped opening or half-circle opening) , the clip holder could be easily slid into the opening without much difficulty.

Referring back to Figures 4a and 4b where the upper clip holder (la) is shown secured in the upper opening (19) and the lower clip holder (lb) is shown secured in the lower opening (20) . The inlet and outlet tubes (16, 17) are bended immediately after passing through the openings forming generally U- shaped tubing as shown in the figures . Such short bent portions are generally preferred to reduce vibration stress to the tube header of the heat exchanger when the air-conditioning apparatus is in operation. As mentioned earlier, the clip holder (la, lb) is preferably made of resin, plastic and other insulative material. Such a material formed isolation barrier between the all aluminum heat exchanger assembly especially between the inlet and outlet tubes and the end plate of the outdoor unit casing or cabinet thus preventing possible galvanic corrosion to the heat exchanger assembly (2) apart from preventing rain water from entering the chamber .

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 .