Motor Compressor Unit With Reduced Noise Transmission

Abstract

In accordance with the principles of the invention, a compressor is provided in a hermetically sealed enclosure with the crankshaft of the compressor being permitted to extend downwardly into the area where lubricating oil is contained within the hermetically sealed enclosure. Mounted on the crankshaft, below the rotor of the electric motor driving it but above its thrust and journal bearing is a stirring member. The stirring member comprises a flat, annular disc which is welded to a spider member so that the annular disc is disposed in an angle relative to the axial length of the crankshaft. Because of the angular offset of the annular disc and its disposition in the oil in the lower part of the hermetically sealed enclosure, rotation of the crankshaft occasions stirring of the oil thereby producing bubbles in the oil body. This lessens the sound transmission quantities of the oil so that a portion of the noise due to the rotation of the electric motor and the operation of the compressor is attenuated and not transmitted outwardly of the hermetically sealed enclosure.

Description

BACKGROUND OF THE INVENTION

This invention relates to the reduction of noise in hermetically sealed motor compressor units and, more specifically, to the reduction of noise in a motor compressor unit which is hermetically sealed and utilized in this configuration in home refrigerators, freezers, air conditioners and the like.

DESCRIPTION OF THE PRIOR ART

Quiet operation is demanded of present day compressors for use in household refrigerators, freezers, air-conditioning equipment and the like, but space and heat requirements preclude any great reduction in the noise level by the use of sound baffles or sound insulation. Hence another method must be utilized to reduce the noise level of motor and compressor units for those applications.

Coupling of the vibrating surfaces of the motor and compressor to the enclosing hermetic shell takes place through (1) the pool of lubricating oil in which a portion of the compressor is immersed; (2) through the atmosphere of the refrigerant gas inside the hermetic shell; and (3) through the mechanical paths of the mounting springs and the discharge piping. It has, therefore, been recognized that the body of oil present in the lower portion of the hermetic shell in which the motor compressor unit is partially submerged provides, to the hermetic shell, a large amount of noise originating in the compressor. It has also been recognized that significant attention of the noise through this path can be accomplished by the generation of bubbles in the oil body to produce a frothy or foamy mixture of oil and refrigerant gas as is shown in U.S. Pat. No. 3,066,857, for example. Such a mixture is less effective in transmitting vibrations than a quiet pool of oil because the bubbles contained in the mixture absorb pressure pulsations of the refrigerant gas and the aforesaid frothy or foamy mixture is less effective in transmitting vibrations than a relatively full liquid pool. However, it is important that the stirring that provides mixing of the oil and refrigerant bubbles produce little resulting noise. Otherwise the noise level from this source will nullify the reduction from other sources within the enclosure shell.

One previously used method of bubbling the oil within the compressor shell was to discharge suction gas into the body of oil through a perforated tube whose perforations were below the surface of the oil body. Another such method was to disturb the oil be means of a screen kicker extending downwardly from the connecting rod. This "kicker" also provided lubrication and was distinguished in its operation by the interrupted action action it provided since it entered the oil only during a portion of each piston cycle.

A more efficient and more economical arrangement utilized for stirring the oil is an apparatus which utilizes a paddle arrangement disposed within the oil bath which continually agitates the oil and thereby produces bubbles of refrigerant therein. Several examples of paddle arrangements are disclosed in U.S. Pat. No. 3,147,914. In this patent either the rotor of the motor driving the compressor is disposed in the oil bath or fingers are formed on the ends of the rotor which are disposed in an oil bath and these fingers utilized for stirring or a substantially integrally shaped stirring member is mounted on the lower portion of the combined crankshaft and motor shaft. Each of these three structural arrangements require substantial modification of the rotor, itself, or a relative intricately designed stirrer element mounted on the motor shaft.

The present invention provides a much more satisfactory means for producing bubbles in the body of oil and involves a positioning of a simplified stirring member mounted on the end of the motor shaft so as to be disposed in the oil body. Consequently, when the motor is running and the compressor operating, the stirrer rotates and continuously churns and aerates or gasifies the oil producing a high degree of bubbles or foaming of the oil thus materially reducing the sound transmitting ability of the body of oil.

SUMMARY OF THE INVENTION

The invention comprises a combined motor and compressor unit disposed in a hermetically sealed shell and in which an oil bath is provided in the bottom portion of the shell to furnish lubrication to the system. The shaft forming the shaft for the motor and the crankshaft for the compressor is disposed in a vertical position within the shell and extends downwardly into the oil bath area where it is pilotingly received by a thrust and journal bearing. Mounted between the thrust and journal bearing for the combined crank and motor shaft is a stirrer means. This means is made up of a spider member and an annular flat disc member with the annular flat disc member spot welded or brazed, for example, to the spider member. The spider member holds the stirrer element formed by the annular flat disc on the combined crank and motor shaft so as to rotate with it. The annular disc member is disposed at a 2.degree. or 3.degree. angle to a line perpendicular to the axis of the combined crank and motor shaft. Because of this angular disposition of the flat disc, rotation of the combined crank and motor shaft provides a churning action to the oil bath in which the stirrer member is disposed. This churning action aerates the oil bath and imparts to it bubbles of refrigerant thereby providing a bath which substantially attenuates the sound and vibrations of the combined motor and compressor contained within the enclosure shell.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical section of a view of a motor compressor unit incorporating the oil stirring means constructed in accordance with the present invention;

FIG. 2 is a cross-sectional elevation view of the stirrer of FIG. 1; and

FIG. 3 is a plan view of the stirrer of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

As shown in FIG. 1 of the drawing, the invention is utilized in a hermetic refrigeration compressor. The compressor unit comprises a two-part shell or case 10 having upper and lower sections 11 and 12 respectively, made of sheet metal or like material of impervious nature which are secured together as by brazing, welding or other suitable joining means to provide a hermetically sealed unit.

The shell 10 houses a compressor 14 and an electric motor 16 for driving the compressor 14. A frame 18 is provided for supporting the compressor and motor in a predetermined structural relationship. This frame includes a portion 20 for receiving a compressor cylinder 22 of the compressor 14 and also includes a motor-supporting portion 24 having an upper half 26 which mates with a lower half 28 to engage and support the electric motor 16. The frame halves 26 and 28 may be maintained in assembled relationship by any suitable means for example by a flange 30 on the lower half which telescopically receives the lower edge of the upper half 26.

A plurality of screws 32 extend through the motor stator 34 to secure the latter to the lower half 28 of the frame portion 24. A spider 36 is formed integral with the frame lower half 28 and has a central portion 38 which provides a combined journal and thrust bearing for the lower end of the vertically disposed motor shaft 40. This motor shaft also extending upwardly to form the crankshaft for the compressor 14. The motor shaft 40 carries fixedly secured thereto a rotor 42 of the electric motor 16. At its upper end the shaft 40 is journaled in a bearing 44 carried by the upper half 26 of the frame portion 24.

The shaft 40 includes an upwardly extending crank arm 46 disposed eccentrically with respect to the longitudinal axis of the shaft 40, this crank arm carrying the free end of a connecting rod 48 through which reciprocatory motion is imparted to a compressor piston 50 disposed in cylinder 22 of the compressor 14.

The entire frame 18 and the motor 16 and compressor 14 supported thereby are in turn supported resiliently from the shell 10 by lugs 52 made integral with the frame 18, with these lugs resting upon springs 54 which, in turn, rest upon lugs or brackets 56 provided on the inner sidewalls of the shell 10.

As is seen most clearly in FIG. 1 the shell 10 contains a body 58 of lubricant, as is conventional in such hermetically sealed motor compressor units, for lubrication of the rotating and reciprocating motor and compressor parts in a manner which is also well known and hence not described in this specification.

In the embodiment illustrated it will be noted that the compressor 14 is mounted above the electric motor 16 so that the motor is disposed partially in the body 58 of lubricating oil. That is, the lower end of the motor stator is disposed in the body 58 of lubricating oil so that cooling of the motor is occasioned by being constantly bathed in this bath. It should also be noted, however, that the rotor 42 of the electric motor 16 does not extend into the bath or body of oil 58 so that no agitation is received in this body of oil by any of the moving parts so far related.

Means are provided on the lower end of the motor shaft 40 for stirring and agitating the body 58 of lubricating oil with this means comprises of a pair of elements, one of these elements being a flat annular disc 60 and the other of these elements being a spider member 62 attached thereto. As can be best seen in FIGS. 2 and 3, flat annular discs 60 takes the general configuration of a conventional enlarged washer and therefore has a bore 64 extending through its periphery and an outside diameter 66 which is smaller in dimension than the inside diameter 68 of motor stator 34 (FIG. 1) so that the flat annular disc 60 is capable of rotation relative to the stator 34 as dictated by the motor shaft 40. Spider 62 takes the form of an enlarged portion 70 which is centrally located relative to the axis of the flat annular disc 60, with this central large portion integrally attached to a pair of downwardly extending arm portions 72, 72. Arm portions 72, 72 include thereon outer terminations formed by bent end portions 74 that extend substantially parallel to the planar surface formed by the flat annular disc 60. These bent end portions provides an easy and convenient fastening means for connection of the spider 62 to the flat annular disc 60, such connection easily being afforded by a spot weld or braze or the like or any other conventional connecting means. The central large portion 70 of the spider 62 includes therein a bore 76 which may be formed by a punching or the like so that the bore 76 has a general elongation to provide an extended bearing lip 78 on its periphery. The diameter of the bore 76 is sized so that it is slightly smaller than the diameter of the motor shaft 40 so that a press fit may be obtained between these two elements to fixedly mount the flat annular discs 60 and spider 62 on the motor shaft 40 for rotation with it.

As set out previously, the bent ends 74 are formed so as to be in a substantial planar relationship with the plane of the flat annular disc 60. However, this planar relationship is provided so that the bent ends 74 are slightly offset from each other so that connection of them to the flat annular disc 60 places the flat annular disc between 2.degree. and 3.degree. from the horizontal. It should be clear that disposing the flat annular disc 60 angularly relative to the horizontal provides, during rotation of this disc, a whipping action in the body 58 of oil so that a multitude of bubbles are formed therein with aeration occurring to mix refrigerant gas into this body 58 of oil. This agitation and the consequent large quantities of bubbles created provides a body of fluid which does not markedly transmit motor and compressor caused vibrations to the shell 10 of the enclosure and thereby attenuates to a considerable degree those noises generated by the compressor and motor and heard outwardly of the hermetic enclosure.

While only a single embodiment of the invention has been shown, it will be obvious to those skilled in the art that many variations can be made therein within the exercise of the inventive faculty. For example, the annular disk 60 and spider 62 could be integrally formed from a single blank by blanking, forming and piercing and this integral unit then mounted on the motor shaft 40 so as to be submerged in the oil bath.

Claims

I claim:

1. In a refrigeration apparatus; (a) a gas-containing shell, (b) a motor compressor unit mounted within said shell and in spaced relationship thereto, (c) a body of oil within said shell, (d) said motor and compressor unit including a shaft rotatable about a vertical axis, (e) the lower end of said shaft being piloted in a bearing means located below the surface of said body of oil, (f) a stirring means mounted on said shaft disposed in said body of oil, (g) said stirring means comprising a spider member fixed to rotate with said shaft and (h) said stirring means including a disc member angularly disposed relative to the horizontal and fixed to said spider member at its bottom to rotate therewith in said body of oil thereby causing agitation of the oil to produce foaming during its rotation and lessening the transmission of sound through the body of oil to the gas-containing shell.

2. In a refrigerator apparatus; (a) a gas-containing shell, (b) a motor compressor unit mounted within said shell, (c) a body of oil within said shell, (d) a shaft mounted relative to said motor compressor, (e) a stirring means mounted on said shaft and disposed in said body of oil, (f) said stirring means including a thin member having a pair of opposed uniplanar surfaces immersed in said body of oil and disposed with said uniplanar surfaces angularly related relative to the horizontal whereby rotation of said thin member within said body of oil agitates said oil causing foaming to reduce the transmission of sound outwardly of said gas-containing shell.

3. The combination set out in claim 2 wherein; said thin member comprises a flat, annular disk.

4. In a refrigeration apparatus; (a) a gas-containing shell, (b) a motor compressor unit mounted within said shell, (c) a body of oil within said shell, (d) a shaft mounted relative to said motor compressor, (e) a stirring means mounted on said shaft and disposed in said body of oil, (f) said stirring means including a uniplanar member disposed angularly relative to the horizontal whereby rotation of said uniplanar member within said body of oil agitates said oil causing foaming to reduce the transmission of sound outwardly of said gas-containing shell, (g) said uniplanar member comprising a flat, annular disk, (h) said flat, annular disk including an outer diameter, (i) said motor compressor unit including a stator, (j) said stator including an internal diameter, and (k) said outer diameter of said flat, annular disk smaller than said internal diameter of said stator.

5. The combination set out in claim 4 wherein; (a) said stirring means includes a spider member, (b) said spider member is comprised of (1) an enlarged central portion, (2) a pair of downwardly disposed arms attached to said central portion, (3) a pair of bent end portion attached to said arm portions, (c) said bent end portions forming a uniplanar surface and (d) said flat annular disk connected to said bent end portions.

6. The combination set out in claim 5 wherein; said spider member is press fit to said shaft.