Title of Invention

HERMETICALLY SEALED COMPRESSOR WITH AN IMPROVED HEAT TRANESFER

Abstract

The present invention provides to a hermetically sealed compressor with an enhanced heat transfer. The hermetically sealed compressor of the present invention comprises a thermally conducting heat transfer element disposed between stator and shell and crankcase and the shell to provide an efficient heat transfer through conduction. The present invention also provides a compressor with a thermally insulated member disposed between stator and the crankcase.

Full Text

The present invention relates to hermetically sealed compressors, more particularly, to heat transfer for hermetically sealed compressors of the reciprocating type. Background of the Invention Figure 1 shows the conventional hermetically sealed compressor that generally comprises a lower and upper shell (22 & 10), inside which three or more resilient members hold the pump assembly (spring mounting, 4). The pump assembly consists of a motor component stator (12) and rotor (14). In addition, the pump assembly also consists of a refrigerant fluid compressor mechanism which having a cylinder bore in the crankcase (3) in which piston (15) reciprocates. The connecting rod (5) holds piston through piston pin (19) and roll pin (21) at its small end for translating rotary motion of the crankshaft (2) to reciprocating motion of the piston in the cylinder. The crankshaft is housed in the main bearing in crankcase and outboard bearing (7). The rotor is fitted directly on the crankshaft and the stator is mounted on the crankcase through fasteners. The motor provides the power required for rotation of the crankshaft. In a conventional hermetically sealed refrigeration compressor as shown in Figure 1, the refrigerant fluid enters through the suction tube and travels into the shell and suction muffler (11), which then goes into the suction plenum in the cylinder head (17) through suction mufflers. During a suction stroke this refrigerant fluid is sucked in to the cylinder bore through valves and ports provided in the valve plate assembly (18). In the compression stroke the refrigerant fluid having a high pressure and temperature enters into the discharge plenum in the cylinder head through discharge valve and ports provided in valve plate assembly. The suction and discharge valves operate on pressure difference. The compressed refrigerant fluid is discharged to condenser through pressure muffler (13), shock loop (8) and discharge tube provided on the shell. Heat generated inside the shell by stator/motor and compression mechanism is transferred to the shell by means of convection. In Figure 1, 24 and 25 depict the convection space available at stator and cylinder head for transferring heat through convection to the outer shell. In this process, the refrigerant fluid picks up heat by heat convection from the motor and pump assembly (hotter components) before it reaches into the crankcase. It is well known from the basics of thermodynamics that refrigerant fluid super heating will result in reduced compressor performance as density of refrigerant fluid reduces with increased temperature which means less mass flow rate in to the cylinder bore. The piston and bearings in the cylinder head are lubricated by lubricating oil provided (20) in the shell, which is circulated through the oil holes provided in the crankshaft. The lubricating oil is sucked due to the centrifugal force created by the rotation of crankshaft through the holes provided in the thrust plate (9). Figure 2 shows the conventional stator/motor (12) and crankcase (3) assembly through the path line, 26. Figure 3 shows the conventional stator/motor (12) and crankcase (3) assembly. The assembly face is as shown as 27. Objects and summary of the invention The object of the present invention is to overcome the abovementioned drawbacks and provide better heat transfer for hermetically sealed compressors which results in high efficiency in particular more cooling capacity which handles more mass flow rate for the same given displacement. Another object of the present invention is to provide better heat transfer by conduction from motor to shell for hermetically sealed compressors which reduces the effect of superheating of the refrigerant fluid to a great extent and improves motor efficiency also. Yet another object of the present invention is to provide better heat transfer by conduction from cylinder head to shell for hermetically sealed compressors which reduces the effect of superheating of the refrigerant fluid to a great extent. Still further object of the present invention is to provide thermal-insulating material where motor is directly mounted on crankcase by fasteners which reduces heat transfer from motor to crank case by conduction. Another object of this invention is to reduce the cavity resonance problems, which in tum reduces the noise or increases quality of sound. To achieve the said objectives this invention provides a hermetically sealed compressor comprising a motor and compressor pump assembly mounted in a shell including a cylinder head and mufflers characterised in that the heat transfer takes place from motor to shell and cylinder head to shell by placing highly thermal conductive material between the stator and the shell and between the cylinder head and the shell such that said conductive material maintains direct contact with the stator of the motor to shell and cylinder head to shell all the time for heat transfer by conduction, thereby changing the volume of gas in the compressor resulting in shifting of the cavity resonance and reducing the operating noise of said compressor. The highly thermal conductive material includes Cu, Al, Steel or a combination thereof. The said highly thermal conductive material is a fluid like Nanofluid. The said Nanofluid is ethylene glycol with copper nanoparticles added to it, An insulating material is placed between the contact points of stator / motor with crankcase. The stator/ motor is mounted on crankcase. Brief Description of the Accompanying Drawings The invention will now be described with reference to the accompanying drawings: Figure 1 is a cross sectional view of a conventional hermetically sealed compressor. Figure 2 is a stator and crankcase assembly path in a conventional hermetically sealed compressor. Figure 3 is a Stator and crankcase assembly in a conventional hermetically sealed compressor. Figure 4 is a cross sectional view of the hermetically sealed compressor in accordance with the present invention. Figure 5 is a close view of stator and crankcase assembly in a hermetically sealed compressor in accordance with the present invention. Detailed description of the accompanying drawings Figure 1 to 3 have already been explained under the heading 'Background of the invention' Figure 4 shows the cross section view of a hermetically sealed compressor according to the present invention. In this type of a hermetically sealed compressor, heat transfer from stator (12) to shell (10) and cylinder head (17) to shell (22) takes place by conduction (29) instead of convection as shown in the conventional compressors of Figure 1 (24, 25). High thermal conductive material (28, 29) placed around the stator (12) and cylinder head (17) in such a way that this material is in direct contact with stator (12) to shell (10) and cylinder head (17) to shell (22) all the time for heat transfer by conduction. The conductive material changes the volume of gas in the compressor resulting in shifting of the cavity resonance and operating noise of the compressor. Figure 5 shows close view of the stator/motor (12) and crankcase (3) assembly with thermal insulating material (30) placed at the contact of stator/motor with crankcase for avoiding heat transfer by conduction. There are several advantages of providing a high thermal conductive material for transferring heat through conduction in a hermetically sealed compressor, which include: - Increase in cooling capacity as mass flow rate increases, - Overall increase in the efficiency of the compressor, - Cost reduction as more capacity for the same displacement, - Increased compressor reliability as compressor operates at low temperature, and - Reduction in noise and improved quality of sound. We claim: 1. A hermetically sealed compressor comprising a motor and compressor pump assembly mounted in a shell including a cylinder head and mufflers characterised in that the heat transfer takes place from motor to shell and cylinder head to shell by placing highly thermal conductive material between the stator and the shell and between the cylinder head and the shell such that said conductive material maintains direct contact with the stator of the motor to shell and cylinder head to shell all the time for heat transfer by conduction, thereby changing the volume of gas in the compressor resulting in shifting of the cavity resonance and reducing the operating noise of said compressor. 2. A hermetically sealed compressor as claimed in claim 1 wherein highly thermal conductive material includes Cu, Al, Steel or a combination thereof. 3. A hermetically sealed compressor as claimed in claim 2 wherein said highly thermal conductive material is a fluid like Nanofluid. 4. A hermetically sealed compressor as claimed in claim 2 wherein said Nanofluid is ethylene glycol with copper nanoparticles added to it. 5. A hermetically sealed compressor as claimed in claim 1 wherein an insulating material is placed between the contact points of stator / motor with crankcase. 6. A hermetically sealed compressor as claimed in claim 1 wherein stator/ motor is mounted on crankcase. 7. A hermetically sealed compressor substantially as herein described with reference to and as illustrated in the accompanying drawings

Documents:

497-che-2003-abstract.pdf

497-che-2003-claims duplicate.pdf

497-che-2003-claims original.pdf

497-che-2003-correspondnece-others.pdf

497-che-2003-correspondnece-po.pdf

497-che-2003-description(complete) duplicate.pdf

497-che-2003-description(complete) original.pdf

497-che-2003-drawings.pdf

497-che-2003-form 1.pdf

497-che-2003-form 13.pdf

497-che-2003-form 26.pdf

497-che-2003-form 3.pdf

497-che-2003-form 5.pdf