Description A COMPRESSOR

[0001] The present invention relates to a compressor the casing of which is cooled

[0002] In hermetic type compressors, the electric motor used in driving the crank - piston rod mechanism, the cylinder-piston mechanism and the other mechanisms are kept in a sealed casing. Since the yield of the electric motor is about 70 - 80 %, the arising loss and particularly the mechanical losses in the bearings result in the heating of the components in the compressor and to increase the temperature of the refrigerant before entering the cylinder thus decreasing its efficiency. In addition to the thermal energy arising from the operation of the electric motor and the mechanical losses, the temperature of the refrigerant also increases which results in heat transfer from the vicinity of the cylinder towards the interior of the casing. In cases when the cylinder cannot be cooled as required, performance is decreased since the compressor input power is increased. All the thermal energy generated due to mechanical losses in the electric motor and the compression process is transferred to the surroundings through the casing when continuous regime is reached. The increase in the temperature of the casing and the components decreases the volumetric efficiency since the refrigerant received into the cylinder decreases in density and also the work amount required during compression increases since the temperature of the cylinder increases. Therefore, cooling the compressor pkys a major role in the capacity of the compressor.

[0003] In conventional applications, ians used for increasing the condenser heat transfer are utilized depending on the positioning of the compressor at the bottom of the cabin in the cooling device and in some applications, in addition the defrost water from melting the frost on the evaporator is delivered to the defrost water container situated on the compressor casing. In this type of applications, the cooling of the compressor casing is not directly aimed and in addition the continuous cooling of the casing can not be provided since defrost water is not always available.

[0004] In the state of the art United States of America Patent numbered US4867657, heat transfer is provided by a plurality of parallel, spaced annular ribs surrounding the outer wall of the compressor casing from the interior of the hermetic shell to the esterior environment.

[0005] In the state of the art United States of America Patent numbered US6666043, a second casing is formed over the compressor casing and a heat exchanger in the space

there between. The fluid entering the heat exchanger evaporates by absorbing the heat of the compressor. In this type of application, since another heat transfer fluid is used that changes phase between liquid and gas, the second shell over the casing should be leak-proof. This application can cause the oil in the casing to be cooled and the oil viscosity to increase due to overcooling of the compressor. Furthermore when the compressor is not cooled sufficiently, the heat exchanger can act like an insulation layer causing the compressor to be overheated.

[0006] In another state of the art International Patent Application numbered WO0240930, a compressor cooled by a fan is explained.

[0007] While the temperature of the oil, some portion of which is in the compressor casing, that circulates within the system is decreased, its viscosity should not be increased. Therefore this fector should be taken into consideration in cooling the casing. Since substantially decreasing the temperature of the other components together with oil will increase the viscosity of oil, mechanical losses will increase.

[0008] The objective of the present invention is to design a compressor wherein performance is increased and energy consumption is decreased by cooling the casing.

[0009] The compressor designed to fulfill the objective of the present invention, explicated in the first claim and the respective claims thereof, comprises a casing formed of two separate parts being an upper and a lower one, fins that are preferably situated on the upper casing and a shell disposed over these fins forming an air channel between the fins, and a Ian that is in continuous contact with the upper casing of the compressor and the fins that are designed to increase the heat transfer surface area, providing the air to flow in the channels formed between the casing and the shell and thus cooling the upper casing.

[0010] In another embodiment of the present invention, the fins disposed on the upper casing are designed in accordance with the profile of the compressor casing, preferably extending towards the center portion of the compressor. Consequently the cooling process of the casing is only realized on the upper casing, the change in temperature of the oil in the compressor lower casing is at a minimum. Since the temperature of the oil is not reduced, there are no changes in the viscosity and mechanical losses and the desired advantage is attained by cooling.

[0011] In another embodiment of the present invention, by positioning the shell produced in accordance with the profile of the compressor upper casing over the fins, separate pathways are formed where air can flow separately in each one and thus providing effective cooling of the compressor casing.

[0012] By means of the present invention, the compressor can be cooled directly and effectively, providing the temperature of the oil in the casing base to be affected as little as possible.

[0013] The compressor designed to fulfill the object of the present invention is illustrated in the attached figures, where:

[0014] Figure 1 - is the perspective view of a compressor.

[0015] Figure 2 - is the exploded view of a compressor.

[0016] The elements illustrated in the figures are numbered as follows:

1. Compressor

2. Hole

3. Upper casing

4. Lower casing

5. Outer shell

6. Fin

7. Fan

8. Opening

[0017] The compressor (1) of the present invention comprises an upper casing (3), a lower casing (4), more than one fin (6) mounted on the upper casing (3) providing to increase heat transfer surlace area, an outer shell (5) arranged over these fins (6) such that there is a space between the outer casing (3), and a Ian (7) mounted on this outer shell (5), providing to cool the upper casing (3) by activating the air and passing through the space between the outer shell (5) and the upper casing (3) (Figure 1 and Figure 2).

[0018] The lower casing (4) forms a base on which the crank - piston rod mechanism, the electric motor used in driving this mechanism, the cylinder-piston mechanism and the other mechanisms are situated and furthermore serves as a reservoir for storing the oil that is used for minimizing the friction effect in the movable parts and to transfer the heat to the outer environment.

[0019] The upper casing (3) is mounted over the lower casing (4) and covers all the mechanisms situated on the lower casing (4).

[0020] The upper and lower casings (3 and 4) are joined to one another in a leak-proof way and serve to protect the crank - piston rod mechanism, the electric motor used in driving this mechanism, the cylinder-piston mechanism and the other mechanisms from exterior agents.

[0021] The fins (6) form a protrusion on the surlace of the upper casing (3) and are preferably produced of aluminum, copper or steel material in accordance with the

shape of the upper casing (3). The fins (6) are affixed on the upper casing (3) of the compressor (1) by adhesion, welding or other known fixing methods. The heat transfer surlace area is increased by utilizing the fins (6). Furthermore the fins (6) serve as a support on which the outer shell (5) can stand on the upper casing (3).

[0022] The outer shell (5) is disposed over the fins (6) so that the air is not dispersed to the environment and the air is directed more intensively over the upper casing (3). Consequently, air channels separate from each other can be formed without air communication in between the fins (6).

[0023] The outer shell (5) comprises a hole (2) that provides the air activated by the Ian (7) to pass in between the upper casing (3) and the outer shell (5). The Ian (7) is mounted over this hole (2) in a leak-proof way and the air aspirated by the Ian (7) reaches in between the outer shell (5) and the upper casing (3) passing through this hole (2).

[0024] The compressor (1) comprises an opening (8) between the outer shell (5) and the upper casing (3), surrounding the upper casing (3) all around, providing the air to go out to the esterior surroundings before reaching the lower casing (4). By means of the opening (8), the air blown by the Ian (7) sweeps over the upper casing (3) and leaves the space between the outer shell (5) and the upper casing (3) and is dispersed to the esterior surroundings without reaching the lower casing (4) which serves as a reservoir wherein the oil collects. Consequently, the cooling process is only realized from the upper casing (3) and since the blown air does not reach the lower casing (4), the temperature difference in the oil that is collected in the lower casing (4) is at a minimum. Thus, the compressor (1) upper casing (3) can be effectively cooled without much affecting the temperature of the oil.

[0025] The Ian (7) is energized preferably as the compressor (1) starts operating and the air aspirated from the esterior surroundings at a comparably lower temperature than the compressor (1) is blown into the air channels formed by assembling the upper casing (3), the fins (6) and the outer shell (5) together. The air that flows between these fins (6), absorb heat by means of the fins (6) and provide cooling of the upper casing (3). Since the cooling process is realized only from the upper casing (3), the temperature difference of the oil that is collected at the lower casing (4) is at a minimum. Consequently the upper casing (3) of the compressor (1) can be effectively cooled without much affecting the temperature of the oil. likewise the cooling capacity is increased by lowering the temperature of the sucked refrigerant and since the temperature of the cylinder is also lowered, the system performance is increased by decreasing the input power of the compressor (1).

[0026] In another embodiment of the present invention, the outer shell (5) has the shape of almost a half sphere.

[0027] In another embodiment of the present invention, the hole (2) whereupon the Ian (7) is mounted preferably extends to the center portion of the outer shell (5) in order to provide a homogeneous air circulation between the upper casing (3) and the outer shell (5).

[0028] By means of the present invention, the compressor (1) can be directly and effectively cooled, providing the temperature of the oil collected in the lower casing (4) to be affected by the cooling process as little as possible.