US1938451A - Compressing apparatus - Google Patents

Description

- 5, 1933. w. B. FLOYD -r AL 1,938,451

COMPRESSING APPARATUS Filed June so, .1930

3 Sheg'as-Sheei; l

m ATTGRQEY- w. B. FLOYD ET AL 1,938,451 comP-REssme APPARATUS 'Dec. 5, 1933.

Fild June 3 19so' :s Sheets-Sheet 2 w a a? Ill/77 WM M 3d INVENTOR S BY W, M r w ATTORNEY ,1 w. B. FLOYD r AL 1,938,451

- COXPRESSING APPARATUS Filed June 30; 1930 3 Sheets-Sheet 3 Patented Dec. 5, 1933 COMPRE SSING APPARATUS William B. Floyd and Alex A. McCormack, Dayton, Ohio, asaignors to Frigidaire Corporation,

Dayton,'Ohlo, a corporation of Delaware Application June so, 1930. Serial No. 464.959

2 Claims. (01.230-58) This invention relates to refrigerating apparatus and more particularly tomotor-compressor units for use in refrigerating apparatus of the compression type.

5 In refrigerating apparatus of the compression type it is customary to provide, among other elements, a compressor having its discharge side connected to a condenser, and its intake side connected to an. evaporator, the evaporator being in turn connected to the discharge side of the condenser through some sort of a pressure reducing device. Refrigeration is produced by evaporating a liquid refrigerant under reduced pressure in the evaporator, the vapors being compressed into, and condensed in a condenser at a much higher pressure. In order to maintain a substantially constant or even temperature within the evaporator, or within the refrigerator which, as a general rule, houses the evaporator, it is customary to operate the compressor intermittently.

That is to say, it is customary to start the compressor when the temperature within the ,refrigerator reaches a predetermined high limit, and to stop the compressor when the temperature is reduced to a predetermined low limit.

Since the discharge side of the compressor is at condenser pressure, and since the intake side of the compressor is at evaporator pressure, it is obvious that the compressor will start under a heavy load and consequently a motor having a high starting torque will be required unless some means is provided for allowing the motor to reach a predetermined speed before the compressor be-,

comes heavily loaded.

It is to such apparatus that my invention relates, having for one of its objects means for automatically loading and unloading the compressor whereby when-the speed of the driving member reaches a predetermined high limit the 40 compressor is automatically loaded and whereby,

when the speed of the compressor or driving member falls below a predetermined limit the [compressor will, be automatically unloaded.

More specifically it is an object of this invention to provide an unloadingdevice which willdepend for its operation upon the presence of lubricating fluid within the compressor. 4

A- furtherobject of this invention is to provide an unloading device in the form of a unitary structure capable of being attached to now existing compressors and capable of being constructed and tested as a unit before being applied to a compressor. Further objects and advantages of the present 156 invention will be apparent from the following descriptiomreference being had to the accom panyin'g drawings, wherein-a preferred form of the present inventionis clearly shown.

In the drawings:

Fig. 1 is a diagrammatical view of a refrig- U crating 'system showing the motor-compressor unit partly in'elevation and partly. in section.

Fig. 2 is a horizontal section talgen on line 2-2 an;12'-2 of Fig. 1.

g. 3 is a section. taken on the line 3-3 of Fig. '1.

Fig. 4 is a view in section taken through the block shown in Fig. 1.

Fig. 5 is a cross-sectional view taken along the lines 5-5 in Figs. 1 and 2;

Fig. 6 is a cross-sectional view taken along the lines 6-6 of Figs. 1 and 2.

In order to illustrate; our invention, we have disclosed diagrammatically a refrigerating system of the compression type having incorporated l5 therein a motor-compressor unit embodying the features of our invention. For instance, we have shown an hermetically sealed motor-compressor unit, generally indicated by the reference character 10, as including a compressor 11, operatively connected to be driven by the motor 12. The compressor is connected to a condenser 14 by means of the conduit 15, and the condenser is in i turn connected on its discharge side to a liquid receiver 16. An evaporator 17 is connected on 86 its inlet side to the liquid receiver 16 and on its. outlet side to the compressor inlet. Refrigerant may flow through the parts in the order named. For instance refrigerant is compressed in thecompressor 11, discharged through the conduit 90 15 into the condenser 14 where it is liquefied and finally collected in liquid form in the receiver 16. From the liquid receiver 16 the refrigerant, in liquid form, flows through the conduit 18 to the evaporator 17. Herein the liquid refrigerant evaporatesunder reduced pressure, to produce a cooling effect, and the vapors. passing through the conduit 19, are recompressed in the compressor 11 to be again discharged into the condenser 14. In order to provide means for maintaining the evaporator, or the refrigerator which generally houses the evaporator, at a substantially constant temperature, means are provided for stopping and startingthe motor at prede-. termined low and high temperature limits respectively. For instance, a switch 20 operatively connected to' a bellows .21 is located in the motor circuit 22, .and the bellows 21 mm open communication through conduit 23, with the suction conduit 18 leading from the evaporator to ll.

the compressor 11. Thus the motor is controlled in response to predetermined high and low pressures within the-evaporator 1'7. In view of the fact that the pressure within the evaporator 1'7 varies with the temperature therein, the motor is in reality controlled in response to predetermined high and low temperatures within the evaporator.

Referring in detail to the motor-compressor unit generally indicated by the reference character 10, we have shown this unit as comprising a compressor casing, generally indicated by the reference character C, enclosing the compressor 11, and the motor casing, generally indicated by the reference character M, enclosing the motor or part of the motor 12, both of these casings being joined together to form an hermetically sealed unit. The compressor casing C includes the plate member having secured thereto by means of the bolts 26, the annular wall member 2'! and the bottom wall member 28. Within the M81118 C is positioned an oscillating cylinder, reciprocating piston type of compressor 11, the cylinder of which is carried by the plate member 25. To this end, a bracket 31 is secured to the plate member 25 as at 32, the bracket 31 extending downwardly and around the cylinder 30. Beneath the cylinder 30, the bracket 31 is provided with a bearing 34 passing therethrough, the bearing being provided with an enlarged head 35 upon which the cylinder 30 oscillates. In order to provide means to guide the cylinder in its oscillating movement, there is provided a shaft 3'7 secured to the cylinder 30 and extending upwardly through a block 38 and plate 25, the block 38 being in turn secured to the plate member 25 by means of a reduced portion 40 passing through and welded to the plate member 25.

A piston 42 reciprocates within the cylinder 30, and is connected to an eccentric 43 formed on the drive shaft 44, the drive shaft 44 being journalled in the upper and lower bearings 46 and 4'7 supported in the sleeve 48, and, the sleeve 48 being in turn carried by the plate 25 and extending upwardly into the motor casing M. A counter balancing weight 92 is also secured to the drive shaft 44.

Rotation of the drive shaft 44 will thus cause T the piston 42 to reciprocate within the cylinder 30 and at thesame time the cylinder 30 and the shaft 3'7 will oscillate on the bearing 35 within,

the limits of eccentricity of the eccentric 43, the cylinder 30 being at the same time urged upwardly against the block 38 by means of a spring 50 surrounding the stem of the bearing 34.

Thus the cylinder 30 oscillates back and forth along the lower side of the block 38, and advantage is takcn of this sliding movement to open and close the inlet to the cylinder 30. Thus an inlet valve comprising an opening 52 in the side wall of the cylinder 30 is provided in the upper surface of the cylinder wall, and this opening 52 is adapted to communicate with the passage 54 formed in the block 38 when the piston is at the end of its suction stroke. The passage 54 formed in the block .38 is connected to the conduit 19 leading from the evaporator 1'7 and a check valve 82 is provided in the passage 19. The cylinder 30 is also provided in its head with anoutlet valve 56of thedisc type.

Thus in operation refrigerant is withdrawn from the evaporator 1'7 through the conduit 19 and pasage 54, and is drawn into the cylinder 90whentheinlctopening52isincommunication with the passage 54. As the piston moves upwardly in the cylinder 30, the opening 52 in the wall of cylinder 30 will move out of communication with the passage 54, due to oscillation of cylinder 30 and the refrigerant within the cylinder 30 will be compressed and discharged through the disc valve into the compressor caslng C.

The motor casing also includes the plate 25 to which is secured the vertical walls 60 and 61 by means of the bolts 62. The vertical wall 61 carries the stator 63 of the motor and the rotor 64 is separated therefrom by means of a nonmagnetic high resistance shell 65 hermetically sealed to the wall 66 which in turn is hermetically sealed to the vertical wall 60 by means of the wall 6'7. Thus the walls 60, 6'7, 66, and 65 form with the compressor casing C, an hermetically sealed unit enclosing the rotor 64 of the motor, and the compressor 11. The rotor 64 is connected to the drive shaft 44 at the upper end thereof and is adapted to drive the compressor 11 through the drive shaft.

Means are provided for properly lubricating the various moving parts of the apparatus and to this end there is provided a body of lubricating oil in the compressor casing C and an oil pump having its inlet in communication with the body of oil and its outlet discharging to the various bearings of the apparatus. For instance, to form an oil pump, the piston 42 of the compressor 11 is stepped as shown at '70 to provide a piston surface 71 reciprocating within the cylinder 30. This oil pump has its inlet '73 communicating with a passage '74, the passage '74 being in turn connected to the conduit '75 communicating with the body of oil in the compressor casing C through a strainer '76. The oil pump also has its discharge opening '77 communicating with a passage 78, which passage communicates with conduit '79, having its discharge end in communication with a space 90 formed between the drive shaft 44 and the sleeve-48. Passage in open communication with the space is adapted to conduct lubricant from the said space to the eccentric bearlng of the drive shaft. Thus as the cylinder oscillates, the oil inlet '73 first communi cates with the passage '74 when piston surface '71 is at its innermost position and then the outlet passage 7'7 communicates with conduit '78 when the piston moves forwardly in the cylinder.

The operation of the apparatus thus far described is substantially as follows. When the compressor is operating, the piston is reciprocating within the cylinder 30, and the cylinder 30 is oscillating on the bearing 3'7, thereby alternately opening and closing the inlet port 52 as the piston is withdrawn and forced into the cylinder respectively. When the inlet port 52 is uncovered, or on the suction stroke, refrigerant is drawn from the evaporator 1'7, through conduit 19, past the check valve 82, through the passage 54 in the block 38 into the cylinder 30. On the upstroke of the piston, the cylinder 30 oscillates to cover the port 52 and the refrigerant is compressed and forced through the outlet valve into the compressor casingC from where the refrigerant in gweous form passes through the conduit 15 to the condenser 14 where the gas is liquefied and collected in the liquid receiver 16. From the liquid receiver 16 the liquid flows into the conduit 18 to the evaporator 17, where it evaporates and again passes in vapor form through the conduit 18 to the compressor. The cycle is thus repeated. At thesametimetheoacillatio' nofqllndrwopenl 'U-shaped cross-section. A spring 112 and closes alternately the inlet and outlet ports of the oil pump, whereby oil is withdrawn irom the compressor casing 0 through the strainer 76 conduit into the inlet passage 73 oi the oil pump, from where it is discharged through the passages 77 and '78 and conduit '79 to lubricate the various bearings 01 the motor and compressor. In order to provide means whereby the compressor 11 and the motor 12 may attain normal.

running speed before the compressor picks up its normal or full load, we have provided a device for maintaining the pressure on the inlet and outside of the compressor substantially the same .until this predetermined normal speed is attained. For instance, we have provided an unloading deviceprovided with a passage communicating with the high and low pressure sides of the apparatus and with a valve therein adapted to be opened when the compressor is idle and to be closed when the compressor attains a predetermined speed. To this end we have provided a unitary structure comprising a block adapted to be secured to the blocker edge 38 of the compressor bymeans of the screws 101. This block 100 is provided with a pasage 102, controlled by valve 104, which passage communicates through a passage 103 formed in block 38 with passage 54 leading to the inlet of the compressor. Thus, it will be seen that when valve 104 is open, high pressure fluid within the compressor casing C will pass through passage 102 to conduit 54 thereby equalizing the pressure on the inlet and outlet sides of the compressor. High pressure fluid in conduit 54 will close check valve 82 thereby preventing the pressure within the evaporator 1'? from increasing.

Means are provided for operating the valve 104 to open the valve when the speed of the compressor ialls below a predetermined minimum and for closing the valve when the speed of the compressor is increased substantially to normal speed. To this end, a bellows 105 is positioned within a second passage 106 within the block 100. This bellows is provided with a rod 107 secured to the lower face of the bellows, the rod 107 being connected through a lost motion connection 108 to a lever 109 pivoted at 110 and connected at its other end to the stem 111 of valve 104. The lever 109 may be made of sheet metal so that in aview transverse to Fig. 2 it would have an inverted surrounding rod 107 takes up the lost motion and maintains the lever 109 quiet in operation. Be-

neath the bellows 105, a passage 114 communi-.

cates with the discharge passage '77 of the oil pump whereby oil pumped by said oil pump will pass upwardly against the face oi. the bellows 105 tending to force the bellows 105 upwardly to close the valve 104.

In operation, the valve 102 will be open when the compressor stops because of the drop in pressure in the lubricant system. It now the switch 20 is thrown to its on-positio n due to a predetermined high temperaturewithin the evaporator 17, the motor 12 will start to drive the compressor. During the first i'ew reciprocations of piston 42, the pressure onthe inlet side 01 the compressor will be equal to the pressure on the discharge side. Consequently when the piston moves back to the left as viewedin Fig. 2, it will draw into the cylinder, gas at the same pressure as in the compressor casing C. As the piston moves to theright therefore, it will do no work, except suflicient to overcome the disc valve 56 P which will be practically negligible. As the mo tor and compressor, and consequently the oil pump, speed up, however, the oil forced by the oil; pump against the lower face of the bellows 105 will collapse the bellows 105 to close the valve 104. Thereupon the compressor will pick up its load and will operate at full load until such time as the compressor and motor fall below a prede-' termined speed due to any cause.

Thus we have disclosed a unitary sell-contained unloading device, one that maybe attached or removed from compressors as a unit; an unload-' ing device that may be tested as a unit before being applied to any of the now existing compressors. 1

Further, while we have shown the receiver 16 as a separate element, the condenser 14 maydischarge into the cavity or depression 120 formed. in the lower wall of the compressor casing C.

While the form of embodiment of the invention as herein disclosed, constitutes a preiferrediform, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. In a compressingunit, a compressor, a cas- 110 ing enclosing said compressor, discharge means for said compressor, intake means for said compressor, one of said means being normally in communication with the interior of said casing, both. of said means having passages to the walloi said 115 compressor, a unitary unloading device attached to the wall of said compressor having a valve opening and closing a connection with the means not normally in communication with the interior of the casing, a pressure responsivev device for operating said valve, said pressure operable device being actuated at a predetermined speed or the compressor.

2. In a compressing unit, a compressor, a cas-.

ioo

ing enclosing said compressor, discharge means for said compressor, intake means for said compressor, one of said means being normally in communication with the interior of saidcaslng, both of said means having passages to the wall of said compressor, a unitary unloading device attaohed l30 to the wall 0! said compressor having a valveopening and closing a connection with the means not normally in communication with the interior of the casing, a pressure responsive device for operatingsaid valve, a lubricating pump operata ing at the same time with said' compressor, the discharge of said lubricating pum'p being connected to said pressure responsive device.

WILLlAM B. FLOYD.

ALEX A. HDCORMACK.

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