WO2003093675A1

WO2003093675A1 - Compressor having noise reducing apparatus

Info

Publication number: WO2003093675A1
Application number: PCT/KR2002/000790
Authority: WO
Inventors: Young-Jong Kim; Byung-Ha Ahn; Jae-Sul Sim; Jong-Hun Ha
Original assignee: Lg Electronics Inc.
Priority date: 2002-04-27
Filing date: 2002-04-27
Publication date: 2003-11-13
Also published as: US20040206104A1; AU2002302984A1

Abstract

In a compressor having a noise reducing apparatus capable of minimizing noise propagated to the outside of a casing (50), by constructing a bottom cap (53) of a casing (50) as a double wall structure (53, 55) and naturally filling oil inside the casing (50) into the double wall, high frequency noise occurred at the bottom cap (53) side can be efficiently excluded, and accordingly a noise absorption efficiency can be maximized.

Description

TECHNICAL EIELD

The present invention relates to a compressor used for an air conditioner or a refrigerator, etc. using a refrigerant cycle, and in particular to a compressor having a noise reducing apparatus which is capable of minimizing noise propagated to the outside of a compressor.

BACKGROUND-ART Generally, a compressor is for converting mechanical energy into compression energy of a compressive fluid, among them a freezing compressor is largely divided into a reciprocating compressor, a scroll type compressor, a centrifugal type compressor and a rotation type compressor, etc. Vibration and noise may occur in the operation of those compressors, herein, high frequency noise occurs mainly due to friction sound between a pressure pulsation sound and parts, and the occurred noise passes the compressor and is propagated to the outside. The propagated noise is a main factor increasing operation noise of an air conditioner or a refrigerator, etc.

Hereinafter, a noise propagation phenomenon in the operation of a compressor and problems thereof will be described on the basis of a Z- compressor disclosed by the present inventor.

Figure 1 is a longitudinal sectional view illustrating a Z-compressor in which the present inventor has disclosed in Korea patent Application No. 10-1999-0042381 in October 1 , 1999 and the Patent Laying-Open Gazette published by Korean Intellectual Property Office in May 7 2001. First, the Z-compressor will be described. The Z-compressor can be regarded as a rotation type compressor, it includes an electric motor part 20 placed inside a sealed casing 10 and generating a rotational force and a compressing part 30 sucking, compressing and discharging a fluid by the rotational force generated in the electric part 20. The electric motor part 20 consists of a stator 22 and a rotor 23 same as a general electric motor.

The compressing part 30 includes a cylinder assembly 31 fixed at the lower portion of the casing 10 and forming a compression space in which a sucked fluid is compressed, a rotational shaft 25 transmitting a rotational force generated in the rotor 23 of the electric motor part 20, a Z- plate 35 combined with the rotational shaft 25, rotating with it and dividing the compression space of the cylinder assembly 31 into a first space V1 and a second space V2, a first and a second vanes 38 and 39, etc. respectively contacted to the upper and the bottom surfaces of the Z-plate 35 by receiving an elastic force from springs 36, 37 and dividing each space V1 , V2 into a suction region and a compression region in the rotation of the Z-plate 35.

Herein, the cylinder assembly 31 includes a cylinder 32, a first and a second bearing plates 33, 34 respectively fixed to the upper and the bottom surfaces of the cylinder 32 and forming the compression spaces V1 , V2 with the cylinder 32.

Particularly, in the Z-plate 35 fabricated as a disk shape in a plane view according to the prior art, the outer circumfenrential surface slide- contacts to the inner circumferential surface of the cylinder 32, the side surface is formed as a sine wave curve cam surface having the same thickness from the inner circumferential surface to the outer circumferential surface. The surface consisting of a top dead center R1 rotates by contacting to the bottom surface of the first bearing plate 33, and the surface consisting of a bottom dead center R2 rotates by contacting to the upper surface of the second bearing plate 34.

In the meantime, a reference numeral 14 is a suction path in which a fluid flows in the casing 10 and the cylinder 32, and a reference numeral

15 is a discharge pipe in which a fluid is discharged to the outside of the casing 10. Reference numerals 40 and 41 are discharge mufflers for lowering discharge noise.

The operation of the Z-compressor will be described. When the rotational shaft 25 rotates by the driving force of the electric motor part 20, the Z-plate 35 combined with the rotational shaft 25 of the cylinder assembly 31 sucks, compresses and discharges the fluid by simultaneously rotating with the rotational shaft 25.

In more detail, the first space V1 placed at the upper portion of the Z-plate 35 is divided into a suction region and a compression region on the basis of the top dead center R1 of the Z-plate 35 and the first vane 38, and the second space V2 placed at the lower portion of the Z-plate 35 is divided into a suction region and a compression region on the basis of the bottom dead center R2 of the Z-plate 35 and the second vane 39. In that state, by rotating the Z-plate 35, the top dead center R1 and the bottom dead center R2 of the Z-plate 35 move, and accordingly volume of the suction region and the compression region of each space is varied.

Herein, the first vane 38 and the second vane 39 reciprocate in the opposite direction each other at the cam surface height of the Z-plate 35.

Accordingly, the fluid is simultaneously sucked into each suction region V1s, V2s of the first and the second spaces V1 , V2 through the suction path 14 and gradually compressed, when the top and the bottom dead centers R1 , R2 of the Z-plate 35 reach a discharge start point, the compressed fluid is simultaneously discharged to the outside of the cylinder assembly 31 through each discharge path (not shown) of each space V1 , V2. After that, the fluid passes each discharge muffler 40, 41 and the casing 10 and is discharged to the outside through a discharge pipe 15.

In the operation of the Z-compressor, lots of noise may be propagated to the outside of the casing 10 due to fraction sound occurred between the pressure pulsation sound and the parts in the fluid discharge,

Figure 2 is a noise radiation distribution view illustrating noise propagated to the outside of the casing 10 in the operation of the Z-compressor.

In more detail, in the casing 10, on the basis of the cylindrical body 11 , the upper cap 12 is combined at the upper portion, and the lower cap 13 is combined at the lower portion in order to seal the internal space. As depicted in Figure 2, noise propagated to the outside of the casing 10 in the operation of the compressor mainly occurs at the lower portion of the casing 10 at which the lower cap 13 is placed. In the meantime, in order to reduce noise occurred at the lower portion of the Z-compressor, when a thickness of the lower cap 13 shown in Figure 3 is increased from 3.5 mm to 4.5 mm, as depicted in Figure 4, a TL (transmission loss) is increased about 2dB.

Accordingly, there is insignificant noise reducing effect. It means noise propagated to the outside in the operation of the compressor can not be efficiently reduced by only increasing a thickness of the lower cap 13.

Therefore, in all compressors using the sealed casing including the above-described Z-compressor, technologies which are capable of maximizing a noise reducing quantity by reducing noise propagated to the outside of the compressor without lowering a performance of the compressor have been required.

XECHNJCAL--GIST_O-=-XhlE-BRESENXINVENT-ION

In order to solve the above-described problems, it is an object of the present invention to provide a compressor having a noise reducing apparatus which is capable of minimizing noise propagated to the outside of the compressor.

In addition, it is another object of the present invention to provide a compressor having a noise reducing apparatus which is capable of maximizing a noise reducing quantity by efficiently preventing noise propagation at the lower portion of a compressor at which comparatively lots of high frequency noise occurs.

In addition, in a compressor using a Z-plate, it is another object of the present invention to provide a compressor having a noise reducing apparatus which is capable of efficiently reduicng noise propagated to the outside.

In order to achieve the above-mentioned objects, a compressor having a noise reducing apparatus includes a sealed casing having a multi- wall structure formed at least at a certain portion thereof and filled with a fluid between walls of the multi-wall.

An oil inflow path is formed at the multi-wall to make oil filled in the casing flow between the walls of the multi-wall.

The casing has a multi-wall structure at the bottom surface. In an embodiment of the present invention, a bulkhead is additionally formed at the bottom surface of the casing to construct a double-wall structure.

In another embodiment of the present invention, a base is formed at the bottom portion of the casing to construct a multi-wall structure, and a fluid is filled in a space between the casing and the base.

The compressor in accordance with an embodiment of the present invention includes an electric motor part placed at the internal upper portion of the casing and generating a rotational force and a compressing part placed at the internal lower portion of the casing, compressing and discharging the fluid by the rotational force generated in the electric motor part.

The compressor in accordance with another embodiment of the present invention includes an electric motor part placed at the internal lower portion of the casing and generating a rotational force and a compressing part placed at the internal upper portion of the casing, compressing and discharging the fluid by the rotational force generated in the electric motor part.

In addition, a compressor having a noise reducing apparatus in accordance with the present invention includes a sealed casing having a cylindrical body, an upper cap combined with the upper portion of the body, a lower cap combined with the lower portion of the body and a bulkhead placed inside the lower cap to construct a multi-wall with the lower cap.

An oil inflow path is formed at the bulkhead to make the oil inside the casing flow and fill therein.

In an embodiment of the present invention, the bulkhead is supported by the lower cap by projecting plural protrusions.

A ratio (d / t,) of a distance (d) between the casing and the bulkhead to a casing thickness (t1 ) is within the range of 0.0 ~ 3.0. In another embodiment of the present invention, the circumferential surface of the bulkhead is fixed to the internal wall of the lower cap.

In further embodiment of the present invention, the circumferential surface of the bulkhead is separated from the lower cap and supported by the lower cap through a supporting rod. The bulkhead is made of a material different from that of the lower cap.

A space between the lower cap and the bulkhead is in a vacuum state. A noise reducing member is inserted between the lower cap and the bulkhead.

In order to achieve the above-mentioned objects, a compressor having a noise reducing apparatus in accordance with the present invention includes a sealed casing having a multi-wall structure at least at a certain portion; a cylinder assembly placed inside the casing and having a suction path and a discharge path; a Z-plate dividing the internal space of the cylinder assembly into plural compressing spaces, sucking, compressing and discharging the fluid while being rotating by an electric motor part; and plural vanes for dividing each compressing space into a suction region and a compression region while performing a reciprocating motion by contacting to the both surfaces of the Z-plate.

In addition, in order to achieve the above-mentioned objects, a compressor having a noise reducing apparatus in accordance with the present invention includes a sealed casing having a multi-wall structure at least a certain portion; a cylinder assembly placed inside the casing and having a suction path and a discharge path; a Z-plate dividing the internal space of the cylinder assembly into plural compressing spaces, sucking, compressing and discharging the fluid while being rotating by an electric motor part; plural vanes for dividing each compressing space into a suction region and a compression region while performing a reciprocating motion by contacting to the both surfaces of the Z-plate; and a noise insulating means placed inside the casing and insulating noise propagated to the outside of the casing. The noise insulating means is constructed by forming a multi-wall structure at least at a certain portion of the sealed casing.

In the compressor having a noise reducing apparatus in accordance with the present invention, it is capable of minimizing noise propagated to the outside of the casing, in particular, by constructing the bottom cap of the casing as the double wall structure and naturally filling oil inside the casing into the double wall, high frequency noise occurred at the bottom cap side can be efficiently excluded, and accordingly a noise insulation efficiency can be maximized.

BRIEE-DESCRIRIiαN-OE-DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

In the drawings:

Figure 1 is a longitudinal sectional view illustrating the prior Z- compressor;

Figure 2 is a radiation distribution view illustrating a level of noise propagated to the outside of a casing of the Z-compressor shown in Figure

1 ;

Figure 3 is a schematic sectional view illustrating a lower cap of the prior Z-compressor; Figure 4 is a graph illustrating a transmission loss according to a thickness variation of the lower cap shown in Figure 3;

Figure 5 is a longitudinal sectional view illustrating a Z-compressor having a noise reducing apparatus according to a first embodiment of the present invention; Figure 6 is a sectional view illustrating a lower cap of the Z- compressor shown in Figure 5;

Figure 7 is a plan view illustrating the lower cap shown in Figure 6; Figure 8 are radiation distribution views respectively illustrating a level of noise propagated to the outside of a casing of the Z-compressor according to the prior art and the present invention;

Figure 9 is a graph respectively illustrating a transmission loss of a Z-compressor according to the prior art and the present invention;

Figure 10 is a graph respectively illustrating a transmission loss according to a thickness variation of the lower cap and the bulkhead in accordance with the prior art and the present invention;

Figure 11 is a graph respectively illustrating a transmission loss according to a space between the lower cap and the bulkhead in accordance with the prior art and the present invention;

Figure 12 is a sectional view illustrating a modified lower cap having a double wall of the Z-compressor in accordance with the first embodiment of the present invention;

Figure 13 is a sectional view illustrating a lower cap having a double wall of a Z-compressor in accordance with a second embodiment of the present invention;

Figure 14 is a sectional view illustrating a lower cap having a double wall of a Z-compressor in accordance with a third embodiment of the present invention;

Figure 15 is a sectional view illustrating a lower cap having a double wall a Z-compressor in accordance with a fourth embodiment of the present invention; and

Figure 16 is a longitudinal sectional view illustrating a Z- compressor in accordance with a fifth embodiment of the present invention.

DETAILEDLDESCRIPT-ION--OE-IHEJN-VENT.IQN

Hereinafter, the preferred embodiments of the present invention will be described with reference to accompanying drawings.

To compare with the prior art, the preferred embodiments of the present invention will be described on the basis of a Z-compressor. However, the preferred embodiments are not limited by the Z-compressor, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.

Figures 5 - 7 illustrate a Z-compressor in accordance with a first embodiment of the present invention, Figure 5 is a longitudinal sectional view illustrating the Z-compressor, Figure 6 is a sectional view illustrating a lower cap of the Z-compressor, and Figure 7 is a plan view illustrating the lower cap of the Z-compressor.

As shown in Figure 5, the Z-compressor having a noise reducing apparatus in accordance with the first embodiment of the present invention includes an electric motor part 60 placed at the internal upper portion of a sealed casing 50 and having a stator 62 and a rotor 63 to generate a rotational force and a compressing part 70 placed at the internal lower portion of the casing 50, sucking, compressing and discharging a fluid by the rotational force generated in the electric part 60.

Herein, the compressing part 70 includes a cylinder assembly 71 having a first and a second bearing plates 73, 74, fixed inside the casing 50 and having a suction path 72a and a discharge path (not shown), a Z- plate 75 dividing the internal space of the cylinder assembly 71 into plural compression spaces, compressing and discharging the fluid while being rotated by the electric motor part 60, vanes 78, 79 dividing each compression space V1 , V2 into a suction region and a compression region in the rotation of the Z-plate 35 while performing a reciprocation motion by respectively contacting to both surfaces of the Z-plate 75.

The electric motor part 50 and the compressing part 70 respectively have the same or similar structure as those of the prior art. However, the casing 50 includes a cylindrical body 51 , an upper cap 52 combined with the upper portion of the body 51 by a welding method, a lower cap 53 combined with the lower portion of the body 51 by a welding method and a bulkhead 55 placed inside the lower cap 53 to form a double wall structure with the lower cap 53, and accordingly it has a different structure from that of the prior art.

In more detail, in order to prevent noise from being propagated to the outside through the lower portion of the casing 50 in the operation of the compressor, the bulkhead 55 is additionally installed to construct a sound insulation space K between the lower cap 53.

As shown in Figures 6 and 7, the lower cap 53 and the bulkhead 55 respectively have a pan structure at which an upper portion is open and are combined each other, and accordingly a double wall structure is constructed. Naturally, so as to be inserted into the lower cap 53, the outer diameter of the bulkhead 55 is the same as or smaller than the inner diameter of the lower cap 53. Accordingly, the circumferential wall portion of the lower cap 53 and the bulkhead 55 are contacted each other, and the bottom surface portions thereof maintain a certain distance to construct a sound insulation space K.

Herein, because plural protrusions 55a are projected from the bulkhead 55 and support the bottom surface of the lower cap 53, a certain space between the lower cap 53 and the bulkhead 55 can be maintained.

It is preferable to form not less than three protrusions to secure a stable supporting structure.

In addition, plural oil inflow holes 55b are formed at the bulkhead

55 to make oil inside the casing 50 flow and fill in the sound insulation space K. Accordingly, the oil inside the casing 50 naturally flows in and fills the sound insulation space K between the lower cap 53 and the bulkhead

55 through the oil inflow holes 55b.

In the meantime, in the first embodiment of the present invention, only the lower cap 53 has the double wall structure in the casing 50, however, it is also possible to construct the body 51 including the lower cap 53 or the upper cap 52 as a double wall structure according to compressor design conditions.

In addition, in the first embodiment of the present invention, the lower cap 53 has the double wall structure in the casing 50, however, it is also possible to construct the lower cap 53 to have a three or a four-wall structure.

The operation and advantages of the Z-compressor in accordance with the first embodiment of the present invention will be described with reference to accompanying Figures 8 - 11.

Figure 8 are radiation distribution views respectively illustrating a level of noise propagated to the outside of a casing of the Z-compressor according to the prior art and the present invention;

As depicted in Figure 8, noise propagated to the outside of the casing 50 in the Z-compressor (B) according to the present invention is significantly reduced in comparison with that of the prior Z-compressor (A). In the test result, generally noise propagated to the outside is reduced about 3 ~ 4dB, it means sound insulation performance is improved.

In particular, in the Z-compressor (B) according to the present invention, high frequency noise mainly propagated from the lower cap portion of the casing 50 is dramatically reduced.

Figure 9 is a graph respectively illustrating a transmission loss of the Z-compressor according to the prior art and the present invention. In comparison with the prior Z-compressor including the lower cap having a single-wall structure as the prior art, in the Z-compressor including the lower cap having the double-wall structure according to the present invention, sound insulation performance (transmission loss) is improved about 30 dB at the frequency region (D) at which a propagated noise question is raised, and accordingly a noise reducing efficiency of the compressor can be maximized. Particularly, in the present invention, because oil inside the casing

50 naturally fills the sound insulation space K between the lower cap 53 and the bulkhead 55 for lubrication and cooling, a resonance frequency generated in the sound insulation space K between the lower cap 53 and the bulkhead 55 can be reduced, and accordingly oil inside the casing 50 can perform a sound insulation function. Accordingly, propagation noise generated in the operation of the compressor can be efficiently reduced with the simple structure.

In the meantime, Figure 10 is a graph respectively illustrating a transmission loss according to a thickness variation of the lower cap and the bulkhead in accordance with the prior art and the present invention. P is a graph illustrating variation of a sound insulation quantity according to a noise frequency variation when a thickness of the lower cap having the single wall as the prior art is 3.2t. A, B and C are graphs illustrating variation of a sound insulation quantity according to a noise frequency variation when a ratio (t₂ / t,) of a bulkhead thickness (t₂) to a casing thickness (t,) as the present invention is respectively 0.1 , 0.3 and 1.

In the test results shown in the comparison graph, the more a thickness difference between the lower cap thickness and the bulkhead thickness, the more a transmission loss is increased, and accordingly a sound insulation efficiency can be improved. Accordingly, it is preferable to have a ratio (t₂ / 1,) of a bulkhead thickness (t₂) to a casing thickness (t,) place within the range of 0.01 - 2.0.

Next, Figure 11 is a graph respectively illustrating a transmission loss according to a distance variation of the lower cap and the bulkhead. P is a graph illustrating variation of a sound insulation quantity according to a noise frequency variation when a thickness of the lower cap having the single wall as the prior art is 3.2t. B.,, B₂ and B₃ are graphs respectively illustrating variation of a sound insulation quantity according to a noise frequency variation when a distance (d) between the casing and the bulkhead is 0mm, 2mm and 3mm on condition that a ratio (t₂ / t,) of a bulkhead thickness (t₂) to a casing thickness (t,) is 0.3.

In the test results shown the comparison graphs, the more a distance (d) between the casing and the bulkhead is increased, the more sound insulation efficiency can be improved. Accordingly, in the present invention, a ratio (d / t,) of a distance (d) between the casing and the bulkhead to a casing thickness (t1 ) is within the range of 0.0 - 3.0.

Figure 12 is a sectional view illustrating a modified lower cap having a double wall of the Z-compressor in accordance with the first embodiment of the present invention. In comparison with the lower cap shown in Figure 6, in a lower cap 53' and a bulkhead 55', a height of each side wall 53a, 55a is increased as Ε' toward the internal space of the body 51 '. Accordingly, because the combined region of the lower cap 53' and the body 51 ' is increased as Ε' height, also noise propagated through the lower portion of the body 51' can be insulated.

Figure 13 is a sectional view illustrating a lower cap having a double wall of a Z-compressor in accordance with a second embodiment of the present invention.

In the above-described first embodiment, protrusions are formed at the bulkhead and supported by the lower cap. However, in the second embodiment of the present invention, protrusions are not formed, the side wall portion as the circumferential surface of a bulkhead 155 is welded and fixed to the internal wall of a lower cap 153.

And, plural oil inflow holes 155a are formed at the bulkhead 155 to make oil inside the compressor flow in the compressor.

Figure 14 is a sectional view illustrating a lower cap having a double wall of a Z-compressor in accordance with a third embodiment of the present invention.

In the third embodiment of the present invention, the outer circumference of a bulkhead 255 is separated from the internal wall of a lower cap 253 to have a certain distance and is supported by the lower cap 253 through a supporting rod 260.

Herein, the supporting rod 260 has a ring shape and forms a space K' between the lower cap 253 and the bulkhead 255, the space K' can be constructed as a sealed-vacuum structure or a gas-filled structure.

In addition, by inserting a sound insulation material such as a glass wool and a rock wool, etc. or a rigid fabric inside the space K', a transmission loss can be improved.

Of course, oil inside the compressor flows in the outer circumference of the space K' to insulate noise propagated to the outside.

Figure 15 is a sectional view illustrating a lower cap having a double wall of a Z-compressor in accordance with a fourth embodiment of the present invention.

In the above-described other embodiments of the present invention, a bulkhead is installed inside a lower cap. However, in the fourth embodiment of the present invention, a base 355 connected to a supporting rod 360 is formed at the bottom portion of a lower cap 353 to construct a multi-wall structure. And, because plural oil inflow holes 353a are formed at the lower cap 353 to make oil flow in the space between the base 355, a fluid is filled in the space between the lower cap 353 and the base 355, and accordingly a propagated noise can be insulated. Figure 16 is a longitudinal sectional view illustrating a Z- compressor in accordance with a fifth embodiment of the present invention.

In the Z-compressor according to the first embodiment of the present invention, an electric motor part is placed at the upper portion of the casing, a compressing part is placed at the lower portion. However, in the Z-compressor according to the fifth embodiment of the present invention, an electric motor part 460 generating rotational force is placed at the internal lower portion of a casing 450, and a compressing part 470 compressing a fluid by the rotational force generated in an electric motor part 460 and discharging it is placed at the internal upper portion of the casing 450.

And, the duublel-wall structure at the lower portion of the casing 450 can be variously formed according to the above-described first - fourth embodiments. In the meantime, in the present invention, because a material of a bulkhead is also major factor for determining propagated noise insulation performance, the same material as a lower cap can be used as a material of the bulkhead, and it is also possible to form a bulkhead with a material different from that of the lower cap.

JN αUSXRI AL-AEP-LIC ABI LITN

In a compressor having a noise reducing apparatus in accordance with the present invention, by forming a certain portion of a casing as a multi-wall structure, noise propagated to the outside of the casing can be minimized.

In addition, in a compressor having a noise reducing apparatus in accordance with the present invention, by efficiently insulating high frequency noise mainly propagated from a lower cap side of a compressor, a noise reducing quantity of the compressor can be maximized.

In particular, in a compressor having a noise reducing apparatus in accordance with the present invention, with a simple structure for making oil inside a casing naturally fill a space between a dual wall, propagated noise occurred in the operation of the compressor can be efficiently reduced.

In addition, in a compressor having a noise reducing apparatus in accordance with the present invention, noise propagated from a compressing part of a compressor using a Z-plate to the outside of a casing can be efficiently reduced. A compressor having a noise reducing apparatus in accordance with the present invention can be applied to not only a Z-compressor but also a reciprocating compressor, a scroll type compressor, a centrifugal compressor and a rotation type compressor, etc.

In addition, a compressor having a noise reducing apparatus in accordance with the present invention can be easily applied to a refrigerator and an air conditioner, etc. using a refrigerating cycle consisting of a compressor, a condenser, an expansive valve and an evaporator. Accordingly, when a compressor having a noise reducing apparatus in accordance with the present invention is applied to a refrigerator or an air conditioner, by minimizing noise occurred in the operation of the refrigerator or air conditioner, a reliability of the product can be improved, and also calm and pleasant circumstances can be achieved.

Claims

1. A compressor having a noise reducing apparatus, comprising; a sealed casing having a multi-wall structure formed at least at a certain portion thereof and filled with a fluid between walls of the multi- wall.

2. The compressor of claim 1 , wherein the fluid filled between the multi-wall is gas.

3. The compressor of claim 1 , wherein the fluid filled between the multi-wall is a liquid.

4. The compressor of claim 1 , wherein an oil inflow path is formed at the multi-wall to make oil filled in the casing flow between the walls of the multi-wall.

5. The compressor of claim 1 , wherein the casing has a multi- wall structure at the bottom surface.

6. The compressor of claim 5, wherein a bulkhead is additionally formed at the bottom surface of the casing to construct a double-wall structure.

7. The compressor of claim 6, wherein an oil inflow path is formed at the bulkhead to make oil filled in the casing flow therein.

8. The compressor of claim 1 , wherein a base is positioned at the bottom portion of the casing to construct a multi-wall structure, and a fluid is filled in a space between the casing and the base.

9. The compressor of claim 8, wherein an oil inflow path is formed at the casing to make oil flow in the space between the casing and the base.

10. The compressor of claim 1 , wherein the compressor includes an electric motor part placed at the internal upper portion of the casing and generating a rotational force and a compressing part placed at the internal lower portion of the casing, compressing and discharging the fluid by the rotational force generated in the electric motor part.

11. The compressor of claim 1 , wherein the compressor includes an electric motor part placed at the internal lower portion of the casing and generating a rotational force and a compressing part placed at the internal upper portion of the casing, compressing and discharging the fluid by the rotational force generated in the electric motor part.

12. The compressor of claim 1 , wherein the compressor includes: a compressing part for compressing and discharging the fluid by the rotational force generated in an electric motor part; wherein the compressing part consists of a cylinder assembly fixed inside the casing and having a suction path and a discharge path, a Z-plate dividing the internal space of the cylinder assembly into plural compressing spaces, sucking, compressing and discharging the fluid while being rotated by the electric motor part, and plural vanes for dividing each compressing space into a suction region and a compression region while performing a reciprocating motion by contacting to the both surfaces of the Z-plate.

13. A compressor having a noise reducing apparatus, comprising: a sealed casing having a cylindrical body, an upper cap combined with the upper portion of the body, a lower cap combined with the lower portion of the body and a bulkhead placed inside the lower cap to construct a multi-wall with the lower cap.

14. The compressor of claim 13, wherein an oil inflow path is formed at the bulkhead to make the oil inside the casing flow and fill therein.

15. The compressor of claim 13, wherein the bulkhead is supported by the lower cap by projecting plural protrusions.

16. The compressor of claim 13, wherein the circumferential surface of the bulkhead is fixed to the internal wall of the lower cap.

17. The compressor of claim 13, wherein a ratio (t₂ / t,) of a bulkhead thickness (t₂) to a casing thickness (t,) is within the range of 0.01 - 2.0.

18. The compressor of claim 13, wherein a ratio (d / 1,) of a distance (d) between the casing and the bulkhead to a casing thickness

(t1 ) is within the range of 0.0 ~ 3.0.

19. The compressor of claim 13, wherein the circumferential surface of the bulkhead is separated from the lower cap and supported by the lower cap through a supporting rod.

20. The compressor of claim 13, wherein the bulkhead is made of a material different from that of the lower cap.

21. The compressor of claim 13, wherein a space between the lower cap and the bulkhead is in a vacuum state.

22. The compressor of claim 13, wherein a noise reducing member is inserted between the lower cap and the bulkhead.

23. The compressor of claim 13, wherein the lower cap and the bulkhead have a pan structure at which the upper portion is open and are combined each other.

24. A compressor having a noise reducing apparatus, comprising: a sealed casing having a multi-wall structure at least at a certain portion; a cylinder assembly placed inside the casing and having a suction path and a discharge path; a Z-plate dividing the internal space of the cylinder assembly into plural compressing spaces, sucking, compressing and discharging the fluid while being rotating by an electric motor part; and plural vanes for dividing each compressing space into a_. suction region and a compression region while performing a reciprocating motion by contacting to the both surfaces of the Z-plate.

25. The compressor of claim 24, wherein a space between multi-wall of the casing is in a vacuum.

26. The compressor of claim 24, wherein a fluid is filled in a space between the multi-wall of the casing.

27. The compressor of claim 24, wherein a noise reducing member is placed between the multi-wall of the casing.

28. The compressor of claim 24, wherein the casing has a multi-wall structure at the bottom portion.

29. _. The compressor of claim 24, wherein a bulkhead is added to the bottom surface of the casing to construct a double-wall structure.

30. The compressor of claim 29, wherein an oil inflow path is formed at the bulkhead to make the oil inside the casing flow and fill therein.

31. A compressor having a noise reducing apparatus, comprising: a sealed casing having a multi-wall structure at least a certain portion thereof; a cylinder assembly placed inside the casing and having a suction path and a discharge path; a Z-plate dividing the internal space of the cylinder assembly into plural compressing spaces, sucking, compressing and discharging the fluid while being rotating by an electric motor part; plural vanes for dividing each compressing space into a suction region and a compression region while performing a reciprocating motion by contacting to the both surfaces of the Z-plate; and a noise insulating means placed inside the casing and insulating noise propagated to the outside of the casing.

32. The compressor of claim 31 , wherein the noise insulating means is constructed by forming a multi-wall structure at least at a certain portion of the sealed casing.

33. In a refrigerator using a refrigerant cycle including a compressor, a condenser, an expansive valve and an evaporator, the compressor comprising: a sealed casing having a multi-wall structure at least at a certain portion thereof and filled with a fluid in a space between walls of the multi- wall.

34. The refrigerator of claim 33, wherein an oil inflow path is formed at the multi-wall to make the oil inside the casing flow and fill in a space between the walls of the multi-wall.

35. In an air conditioner using a refrigerant cycle including a compressor, a condenser, an expansive valve and an evaporator, the compressor comprising: a sealed casing having a multi-wall structure at least at a certain portion thereof and filled with a fluid in a space between walls of the multi- wall.

36. The air conditioner of claim 35, wherein an oil inflow path is formed at the multi-wall to make the oil inside the casing flow and fill in a space between the walls of the multi-wall.