US3270952A - Protective device for compressors - Google Patents

Description

2 Sheets-Sheet 2 Sept. 6, 1966 F. o. BELLMER PROTECTIVE DEVICE FOR COMPRESSORS Filed April 26, 1965 FIGQQ FRIEDRICH o. BELLMER United States Patent 3,270,952 PROTECTIVE DEVICE FOR COMPRESSORS Friedrich 0. Bellmer, East Grange, N..I., assignor to Worthington Corporation, Harrison, NJ., a corporation of Delaware Filed Apr. 26, 1965, Ser. No. 450,785 16 Claims. (Cl. 230-58) In general, this invention relates to a new and improved protective device for gas compressors and, more particularly, to a device which prevents damage to compressors, especially in refrigerant applications wherein damage is often caused by liquid refrigerant entering the compressor during operation.

In a refrigerant system, there occurs, for many reasons, such as temperature and pressure condition changes or the like, the entrance of liquid refrigerant into the gas inlet of the compressor. If the liquid refrigerant enters the cylinders of reciprocating compressors or into the compression chambers of rotary compressors, enormous hydraulic pressure may build up in said chambers causing damage to the affected compressor parts. This is due to the incompressability of the liquids.

In the past, conventional reciprocating compressors have used spring loaded cylinder heads which will lift up if liquid enters the cylinder. With rotary compressors or other types of compressors with positive displacement, a similar liquid relief valve has been used. However, these devices are expensive because they required high loaded springs. For example, in a five-horsepower compressor, the springs must be loaded to 3000 to 4000 lbs. These types of relief members are also not effective in high speed compressors because of the great inertial mass of the cylinder heads and springs which retard the operation of the liquid relief valve thus allowing pressures to build up to dangerous values.

Another basic system for preventing liquid from reaching the immediate suction inlet of a compressor is by utilizing the centrifugal action of the circularly directed gas flow around the inside of a cylindrical chamber. This system, however, will not operate if a large amount of liquid has filled up in the chamber.

Therefore, it is the general object of this invention to avoid and overcome the foregoing and other difficulties of the prior are practices by the provision of a new and better device for preventing liquid from entering the gas inlet of a compressor.

Still another object of this invention is the provision of a new and better protection device for gas compressors which is inexpensive to manufacture, simple to install and which will automatically operate without regard to the speed of the compressor.

A still further object of this invention is the provision of a new and better protective device for a gas compressor which will operate to allow gases to enter the compressor even though small amounts of liquid are initially entrained in the gas as it enters the compressor housing.

Another object of this invention is the provision of a new and better protective device for gas compressors which is operative to eliminate liquids prior to their entrance into the gas compressor and which will return to normal operating conditions after flooding of the compressor inlet without outside aid.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there are shown in the drawings forms which are presently preferred; it being understood, however, that this invention is not limited to the precise arrangements and instrumentalities shown.

In FIGURE 1, there is shown, schematically, a refrigeration system utilizing the compressor protective apparatus of the present invention.

3,270,952 Patented Sept. 6, 1966 ice FIGURE 2, is a cross-sectional view of a compressor built in accordance with the principles of the present invention.

FIGURE 3, is a partial enlarged cross-sectional view of the gas inlet to the compressor before flooding of the compressor housing.

FIGURE 4, is a cross-sectional view similar to FIG- URE 3 after flooding of the compressor housing.

FIGURE 5, is a bottom plan view taken along lines 5-5 of FIGURE 3.

FIGURE 6 is a partial cross-sectional View similar to FIGURE 3 of the second embodiment of the protective device for compressors of the present invention.

7 FIGURE 7 is a bottom plan view taken along lines 77 of FIGURE 6.

FIGURE 8 is a cross-sectional View of one of the valves utilized in the embodiment of FIGURES 6 and 7 when the compressor housing is not flooded.

FIGURE 9 is a cross-sectional view of the valve of FIGURE 8 when the compressor housing has been flooded.

In FIGURE 1 there is shown in general form a refrigeration system generally designated by the numeral 10 and including the usual condenser 12, evaporator 14, and compressor 16 serially arranged with the output of the evaporator being connected to the compressor inlet 18 and the compressor outlet 20 being connected to the inlet of the condenser 12. It would be understood that, in normal operation, it is expected that the evaporator will transmit refrigerant vapor to the compressor inlet 18.

However, as was stated previously, for various reasons such as temperature and pressure condition changes, liquid refrigerant may reach the gas inlet 18 of the compressor 16 and enter into the compressor to cause damage thereto.

The compressor 16 comprises a compressor unit 22 driven by a motor 24 both mounted within a compressor casing 26. The rotating portion 28 of the compressor unit 22 and the rotor 30 of the motor 24 are mounted on a common shaft 32. The casing 26 is divided into a compressor unit half 34 and a motor unit half 36 by a partition 38 having a port 40 connected between the motor unit half 36 and the compressor unit half 34. The port 40 communicates with the interior of a compressor unit shell 42 and a motor unit shell 44 on opposite sides of the partition 38. The stator 46 of the motor 24 fits suitably within the motor shell 34. Accordingly, gas from the evaporator 14 entering the inlet 18 must pass through the groove 48 between the shell 44 and stator 46 to enter the passageway 14 into the compressor unit half 34. The gas entering the inlet 18 first contacts a baffle plate 50 mounted on a wall adjacent to the inlet 18 and adapted to deflect gases in a manner whereby the gas will be forced tangentially about the inner wall of the casing 26 within chamber 36. The gas flow circulating around the inner wall of casing 26 will separate incoming liquid from the gas. This liquid will tend to accumulate at the bottom of the chamber 36 and will normally evaporate after a short time. The gases, including the evaporated liquid refrigerant then passes through an annular groove 52 formed at the free end of the shell 44 prior to entering the groove 48. Within the annular groove 52 there is positioned a suitable washer 54 having a thickness greater than the thickness of the passageway 48 for reasons which will be discussed. The washer 54 rests on pins 56 secured to the shell 44. The washer 54 further provides a very narrow passageway 58 between the stator 46 and the main body of the washer 54 for reasons which will become obvious with respect to the discussion of the operation of the condenser protective system of the present invention.

As was stated, in normal operation, gas enters the inlet 18, impinges on the curved baffle wall 50 and is directed 3 tangentially along the inner wall of the casing 26 within the motor unit chamber 36. The gas flow circulating around the inner wall separates incoming liquid from the gas. Any such liquid would then accumulate at the base of the chamber 36 and would normally evaporate after a short time. The gases flow upwardly through the groove 52 about the washer 54 and through the passageway 48, thus cooling the motor. These gases will be drawn by the compressor unit 22 through the passageway 40 and discharged through an opening 60 within the compressor unit 22 so that the gases will pass out through the outlet 20 into the condenser 12.

The weight of the ring 54 and the area of the gap formed between ring 54 and the sleeve 44 are chosen in a way that the friction of the passing suction gas will not lift up the ring 54 from the resting position on the pins 56.

If the condition arises that, by sudden temperature changes or control failure, or by any other reason, a large amount of liquid refrigerant mixed with gas or not, enters into the motor unit chamber 36, said chamber will first be filled up to the level indicated by the level line 62 immediately above the pins 56 without interfering with the compressor performance. However, at the moment liquid within the chamber 36 rises to a point wherein it fills the groove 52, the ring 54 will lift up from the pins 56 by reason of the hydraulic frictional forces thereon to close the lower openings of groove 48, thus blocking off the liquid fiow. The lifting force acting on the ring 54 caused by the liquid flow, is, as an example, an average of about eighty-five times greater than the force caused by the gas flow, due to the ratio of density of gas to liquid refrigerant.

However, to resume normal operation, after the refrigeration system has been stabilized by a conventional process, and no more liquid flows into the chamber 36, the existing liquid in the chamber has to be brought back into the system.

During flooding of the casing as shown in FIGURE 4, the existing liquid in the chamber 36 will be vaporized and pumped out by the compressor. This operation is accomplished by the provision of the small gap 58 between ring 54 and stator 46. The liquid being sucked through the gap 58 will spray out into the passageway 48 and the space between the motor 24 and partition 38 within shell 44 where a pressure of almost vacuum exists. This spray will be gaseous as the ring 54 is in the closed position as shown in FIGURE 4, and the continuous running of the compressor 28 causes a vacuum in the manner discussed previously and, additionally, the electric motor 24 runs at a high temperature. This combination of high temperature and low pressure cause the vaporization of the liquid.

If the liquid in the chamber 36 drops by reason of the above evaporation, under the level 62, the ring 54 will drop by its own weight, to the open poistion shown in FIGURE 3 resting on the pins 56. The remaining liquid in the chamber 36 will evaporate completely after a certain time and be pumped out gradually by the compressor.

The gap 58 has, besides serving as a liquid bypass, the special purpose of equalizing the gas pressure over and under the ring 54 when the ring is in the closed position of FIGURE 4 and the liquid has dropped under the level 62. If the bypass gap 58 was not present, the diflerential pressure achieved by the evacuation of passageway'48 and the gas pressure in chamber 36 would keep the ring 54 up in the closed position of FIGURE 4 and restrict further gas flow.

The same type of compressor protection is achieved by the compressor 16' shown in FIGURES 69. In this showing, it will be understood, that prime numerals indicate parts similar to those shown in FIGURES 1-5.

Here again, the compressor includes a motor unit chamber 36' into which gas is fed through the inlet 18 which impinges on baffle 50. Bafile 50' directs gas tangentially along the inner wall of the casing 26' so as to separate liquid from the gas. The motor 24' having a stator 46' is positioned within the shell 44 and formed with a passage 48. The free end of the shell 44' has vertically positioned valves 64 at spaced points about the circumference of the shell 44. In all other ways, the shell 44 is sealed to the outer surface of the stator 46. Thus, gas within the chamber 36 can only enter the passageway 48 through the valves 64. The valves 64, as shown in the open position of FIGURE 8, have an inlet 66 at the lower end thereof and an outlet 68 at the upper end thereof communicating with the passageway 48'; Within each valve 64 there is provided a vertically'movable closure member 70 having a conical face 72 and a flat bottom face 74 adapted to rest on a tubular support 76. The stem 78 of the actuator 70 telescopes through the tubular support 76 and has an end stop 80 at the bottom thereof. In the open position, the actuator 70 rests on the tubular support 76 and allows gas to pass between the conical portion 72 and the conical valve seat 82 and, thence, through the outlet 68. The actuator 70 may have a lower specific gravity than the refrigerant liquid and, accordingly, when liquid fills the chamber 36 and closes inlet 66, the actuator 70 will move upward to the position shown in FIGURE 9 by flotation as well as bydraulic frictional forces. There, the bottom end stop 80 rests against the bottom surface of the tubular support 76 limiting the upward movements of the valve actuator 70. The limit of movement of the valve actuator 70 prevents the seating of the valve seat 82 with the conical face 72 of the valve actuator. This leaves a small gap between the conical face 72 of the actuator 70 and the valve seat 82. Gap 84 is similar in operation to the gap 58 described with respect to FIGURES 14. That is, the gap 84 allows only minute particles of liquid to pass therethrough when the actuator 70 is in the closed position of FIGURE 9, which liquid when passing between the actuator 70 and the valve seat 82 will vaporize as it enters the enlarged passageway 48. Further, when the liquid level has dropped, the pressures above and below the valve actuator 70 are easily equalized by reason of the passageways 84 and, accordingly, the valve actuator 70 will return to the position shown in FIGURE 8.

It will be understood that the valve actuator can have a greater specific gravity than the refrigerant liquid and rely mainly on hydraulic frictional forces to lift the actuator into the closed position.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims rather than to the foregoing specification as indicating the scope of the invention.

I claim as my invention:

1. Apparatus comprising:

(a) a casing,

(b) a motor disposed within said casing,

(c) a shell positioned within said casing about said motor,

(d) said motor being operative to drive means for withdrawing gas from within said shell,

(e) partition means for dividing said casing into two portions,

(f) said motor and shell being positioned in one of said portions of said casing,

(g) said casing having an inlet opening for int-roducing fluid into said lower portion,

(h) said shell having an inlet opening to allow fluid to pass from said lower portion into said shell,

(i) valve means at said shell inlet opening operative in a sealed position thereof to seal said shell inlet opening when liquid is collected in said shell up to the level of said shell inlet opening,

(j) said valve means including a valve actuator operative to be forced into a said sealed position when liquid in said casing reaches the level of said shell inlet opening.

2. The apparatus of claim 1 including:

(a) bleed means for providing a gas bleed passage between said shell inlet opening and said one portion when said valve actuator is in said sealed position so as to balance the pressures on opposite sides of said valve actuator after the liquid level has dropped below said shell inlet opening.

10. The apparatus of claim 1 wherein:

(a) said valve actuator has a specific gravity less than the specific gravity of said liquid collected in said one casing portion.

11. Protective apparatus for a compressor for a refrigerant gas comprising:

(a) a casing, (b) a motor disposed within said casing and having a stator and rotor whose common axis is vertically 3. The apparatus of claim 2 wherein said bleed pas- 1 isp sed, sage is located adjacent the stator of the motor whereby a cylindrical Shell Positioned Within Said casing heat from the motor will vaporize any liquid which about the Stator of Said motor, might pass through said bleed passage. (d) said motor having a compressor driven by said 4 h apparatus f l i 1 h i rotor, said compressor being operative to withdraw (a) said motor is disposed with the axis of its rotor Tofrigorant gas from Within Said Shell,

in a Vertical Position, (6) partition means for dividing said casing into an (b) said valve actuator including an annular ring PP? and lower P resting on a bottom limit stop, (if) sa d motor and shell being positioned in said lower (c) said shell inlet opening being positioned im- P P of sald mediately above said annular ring and adapted to be (g) SaI1d compFessol: bemg Posltloned m Sald upper closed by said annular ring upon lifting of said Pom,on OfQSmd i annular ring from said bottom limit stop by reason (h) t casmg hfwmg Inlet opemPg for mtroducmg of the rise in liquid level in said one portion. refnge rant gas Into 531d lower P f The apparatus of claim 4 wherein: (i) the inner wall of said cylindrical shell defining (a) said shell inlet opening is defined by an annular with said stator an inlet opening to allow refrigerant space between the inner wall of said shell and the to Pass from l lower .pomon t Sald i outer surface of the stator of said motor, said shell Valve means. fi sald Shell opening Operative inlet opening having a thickness less than the thickm a seal .posltlon. Sald l openmg ness of Said annular ring, when refrigerant liqu d is collected in said shell to (b) said annular ring having a pass-age on the inner the llwel of Sand shellmlet 9 surface thereof for equalizing pressures on opposite (k) .sald valvqmemts mchldmg l actuator 9 sides of said ring when the liquid level in said one {lave be .hfted Into Sald Seal Posmon. when hgmd portion has dropped below the level of said Shell in said casing reaches the level of :said shell inlet inlet opening. openmg l 6. The apparatus of claim 1 wherein said valve actua- (I) gas'hqllld separatlon posmoned zldlwcept t tor includes: said casing inlet opening for separating liquid (a) a vertically reciprocal member, entra ned in gas passing through said casing inlet (b) said vertically reciprocal member having assozfig q prevent hqmd from entenng sald shell ciated therewith upper and lower limit stops for Th op f l 11 h limiting respectively uppermost position and lower- 40 appalla O 6 w most Position of Said member, (a) sa d gas-liquid-separat ion means lIlCllldCS a battle,

(c) said uppermost position of said vertically recipro- Sald baijfle bemg positioned adjacent Sald casmg cal member being a point immediately adjacent said Inlet. i shell inlet opening to define between said shell and (c) Sald casmg mlet oPemng be mg Tjosltomed above said member a bleed passageway through which theliwel Shenm1et 9 liquid cannot normally flow and, through which Sa 1d bflme bemg {P to dlrect gas and gas gas will pass to balance pressures on opposite sides hqfnd mlxtflres enter 1ng Said lower Portion through of said vertically reciprocal member when the liquid caslflg Inlet openlng against the inner Wall of Said level in said one portion of said casing drops below s a tFmgEBti-QI manner to Separate liquid the level of said shell inlet opening. entrained in said gas and thus aid in preventing liquid 7. The apparatus of claim 1 wherein: from entering Said Shell inlot p (a) said means for withdrawing gas from within said The apparatus f Claim 11 wherein:

1 11 i a compressgr (a) said valve means includes a plurality of separate (b) id compressgr b i t d i h th f valve actuators spaced about the periphery of said said portions of said casing on the opposite side of shell adjacent said shell inlet opening. side partition means from said motor, 14. The apparatus of claim 13 wherein:

(c) said compressor being in communication with the (a) each of said valve actuators has an upper and lower interior of said shell by reason of a passage through li i stop, 531d P (b) said valve actuator upper limit stop preventing f opp of 9131111 1 mcllldlflgi complete sealing of said shell inlet opening and pro- 2 o I lq tf :i p i ri means Wlthln Sald lower P viding in the seal position of said valve actuator a 1 K cas g, bleed passage for equalizing the pressure above and z gi l g i' ii gzfi ggs e gigjin t hi i i ggg below said valve actuator after liquid in said lower casing inlet p g prior to the p a g if Said position has dropped below said shell inlet opening.

15. The apparatus of dam 11 wherein: gas through said shell inlet opening. p 1 t t 1 9. The apparatus of claim 8 wherein: (a) San va ve ac ua or comprising an annu ar ring (a) said liquid-gas separation means includes a baffle havmg sgeclfic i y less than the 'Speclfic gravlty positioned adjacent said casing inlet opening, of h refngemn? hquldf (b) said bame being operative to direct gas and gas (b) said annular ring hav1ng :ath1ckness greater than with liquid entrained therein, entering through Said the thickness of sa d shell inlet opening to seal said casing inlet opening, tangentially against the inner shell Inlet opamng the Seal Positionwall of said casing within said lower portion to Tho pp of Claim 15 wherein! separate t i d li id f gas prior to h (a) said shell has an annular groove adjacent the lower sage of aid gas th o h id h ll i l t i edge thereof extending from the lower edge thereof to said shell inlet opening within which groove is seated said annular ring,

(b) said shell lower edge having integral therewith a limit stop for limiting the downward movement of said annular ring,

(c) said annular ring having a passageway on the inner surface thereof adjacent the stator of said motor to form a bleed passage when said annular ring is in the sealed position and further, to cause any liquid passing through said bleed passage to come into heat exchange relation with said stator 50 as to vaporize said liquid prior to entry into said shell inlet opening.

References Cited by the Examiner UNITED STATES PATENTS 11/1929 Frickey et a1.

9/ 1965 Boettcher 230-207 References Cited by the Applicant UNITED STATES PATENTS 2,605,779 8/ 1952 Smithisler, 2,639,671 5/ 1953 Wagner. 2,902,044 9/ 195 9 Sherer et a1. 2,908,282 10/1959 Maisch. 3,081,788 3/1963 Lewis. 3,082,465 3/1963 Wood.

ROBERT M. WALKER, Primary Examiner.

Claims (1)

1. APPARATUS COMPRISING: (A) A CASING, (B) A MOTOR DISPOSED WITHIN SAID CASING, (C) A SHELL POSITIONED WITHIN SAID CASING ABOUT SAID MOTOR, (D) SAID MOTOR BEING OPERATIVE TO DRIVE MEANS FOR WITHDRAWING GAS FROM WITHIN SAID SHELL, (E) PARTITION MEANS FOR DIVIDING SAID CASING INTO TWO PORTIONS, (F) SAID MOTOR AND SHELL BEING POSITIONED IN ONE OF SAID PORTIONS OF SAID CASING, (G) SAID CASING HAVING AN INLET OPENING FOR INTRODUCING FLUID INTO SAID LOWER PORTION, (H) SAID SHELL HAVING AN INLET OPENING TO ALLOW FLUID TO PASS FROM SAID LOWER PORTION INTO SAID SHELL, (I) VALVE MEANS AT SAID SHELL INLET OPENING OPERATIVE IN A SEALED POSITION THEREOF TO SEAL SAID SHELL INLET OPENING WHEN LIQUID IS COLLECTED IN SAID SHELL UP TO THE LEVEL OF SAID SHELL INLET OPENING, (J) SAID VALVE MEANS INCLUDING A VALVE ACTUATOR OPERATIVE TO BE FORCED INTO A SAID SEALED POSITION WHEN LIQUID IN SAID CASING REACHES THE LEVEL OF SAID SHELL INLET OPENING.

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