US2369841A

US2369841A - Variable capacity compressor

Info

Publication number: US2369841A
Application number: US436520A
Authority: US
Inventors: Charles R Neeson
Original assignee: Chrysler Corp
Current assignee: Old Carco LLC
Priority date: 1942-03-27
Filing date: 1942-03-27
Publication date: 1945-02-20
Anticipated expiration: 1962-02-20

Description

- Feb. 20, 1945. c. R. NEESON I 2,369,341

I VARIABLE CAPACITY COMPRESSOR Filed March 27, 1942 v 3 Sheets-Sheet 1 all l ["61 INVENTOR ,5 diaries 7z/ s ry.

1 w; 44m; ATroRNEYs.

Feb. 20, 1945. R NEESON 2,369,841

VARIABLE CAPACITY COMPRESSOR Filed March 27, 1942 3 Sheets-Sheet 2 INVENTOR C'idrzes' I? lyeesam I B l #1, 7M" x ATTORNEY5- Feb. 20, 1945; Q NEESQN 2,369,841

VARIABLE CAPACITY COMPRESSO? Filed March 27, 1942 3 Shets-Sheet 5 Patented Feb. 20, 1945 UNITED STATES PATENT OFFICE VARIABLE caracrrr comnnssoa Charles R. Neeson, Dayton, Ohio, assisnor to Chrysler Corporation, Detroit, Mich., a corporation of Delaware Application March 27, 1942, Serial No. 436,520

15 Claims.

The present invention relates to compressors particularly adapted for use in refrigeration systems. The present invention comprises an improvement upon the inventions disclosed in my ber of cylinders of a multiple cylinder compressor operating at any given' instant, varies in proportion to the suction pressure of the refrigerant I which, in turn, is a measure of the load upon the refrigerating system to which the compressor is connected. The loading or. unloading of a cylinder, as disclosed in Patent No. 2,185,473, is accomplished by control of the suction valves through which refrigerant gas is permitted to enter the cylinders, the valves associated with certain cylinders being held in open position when the load is lightest and being permitted to open and close in regular compressing manner when the load increases.

. In the years of commercial operation of the inventions disclosed in the aforesaid patents, the value thereof has been demonstrated time and again and certain unforeseen values have come to light. The primary object of the development of the prior inventions was ditionlng system which would maintain a practically constant temperature by variably supplying the air conditioning surface with refrigerant,

as distinguished from the prior practice or permitting a compressor of constant capacity to cycle on and on to create altemate'wa'ves of extremely cold airand warm 'air. This primary purpose has not only been demonstrated in a multitude of installations as being of extreme advantage, but also other uses have come to light particularly in commercial installations of refrigeratio such as, for example, in photograph developing where a constant temperature must be main- .tained, ingreenhouses'and cut flower boxes where plants and flowers will die or wilt under fluctuations in temperatures, and infood or meat storage roomswhere bacteria sometimes increase toa dangerous extent if the room is permitted to warm at any time to a temperature abovethe' desired point. With the use of my compressor, permitting continuous operation of, thesystem to to provide an air conmaintain a substantially constant temperature,

waste is materially prevented. Accordingly, the demand for. adaptation of all of the advantages disclosed in my prior patents, particularly in Patent No. 2,185,473, to smaller capacities of refrigerating systems, such as for fractional horsepower air conditioning units, household refrigerators, household meat or milk coolers, mobile photograph development units, and numerous other applications, has increased to a tremendous extent. Accordingly, the primary object of my present invention is .to provide variable capacity unloading means in acomp'ressor of fractional horsepower or of' relatively small maximum capacity.

A further object of the present invention is to provide variable capacity unloading means in a compressor, the unloading means being of such a nature as to be more easily manufactured and assembled than the type disclosed in my prior patents.

A further object of my present invention is to provide a compressor lubricating and cooling systern, and associated variable capacity unloading means, in a compressor which by the substitution of a fewsimple parts may be of the type having a motor hermetically sealed within 'a casing enclosing the compression apparatus or of the type having an externally driving means such as a motor with its shaft connected to the shaft of.

the compression apparatus through a shaft seal.

A further object of the present invention is toprovide a variable capacity compressor unloading means-involving a minimum of sturdy, easily manufactured and assembled parts.

These and other objects and advantages of the present invention may be more readily under stood by reference to the following specification and accompanying drawings wherein like numerals refer'to\,like parts throughout.

V In the drawings, I Fig. 1 is a vertical, longitudinal section through the preferred form of the present inventio g. 2 is a vertical, longitudinal section through the: preferred form of'the' invention taken substantially at ri ht angles to the plane of Fig. 1; Fig.8 is a bottom .view of the preferred form of the invention; V

Fig. 4 is a horizontal section through a portion of the apparatus taken substantially along line Fig. 5 is a vertical sectional view of a portion of the apparatus taken substantially along line 8-! ofl'lg. 1:

Fig. 6 is a vertical view of a portion of the apparatus disclosed in Fig. 1;

Fig. 7 is a horizontal sectional view taken substantially along line l--1 of Fig. 6; and

Fig. 8 is a partial sectional view taken in the same plane as that of Fig. 2, showing a modification of the present invention.

The compressor preferably includes three main castings comprising a body casting iii, a top casting I I, and a bottom casting l2, the three castings being joined by suitable bolts and gaskets to form a. hermetically sealed housing.

The body casting i is provided with a plurality of cylinder seating openings iii, the number of which may vary from one to as many as can be permitted by the relative diameters of the cylinder seating openings and the main body casting. The cylinder seating openings are placed radially about the main casting and are vertically oifset to permit the attachment of a plurality of connecting rods H to the crankpin l of a crankshaft 58 which is mounted in bearings i1 and 18 at the ends of a journal is cast integrally with the main casting ill. Each connecting rod 14 is connected to and operates a piston 20 which reciprocates within cylinder sleeves 2| supported in the cylinder seating openings 13. The sleeves 21 extend through an annular suction chamber 22 having provision for connection (not shown) with the suction pipe extending from the refrigerating system to which the compressor may be connected.

Expanded refrigerant is drawn into the cylinder sleeve 2| from the suction chamber 22 through an annular suction valve 23 when the piston is retracted, and the compressed refrigerant is discharged through a discharge valve 25 when the piston is extended. The suction valve 23 seated adjacent its inner diameter on the end of the cylinder sleeve 2| and adjacent its outer diameter on a valve seating ring 25 positioned within the cylinder receiving space l3. The gas-may enter the cylinder space through a series of openings (not shown) extending through the ring 25. The gas may be discharged from the cylinder sleeve through a'series of openings (not shown) in adischarge valve retaining member 26 which is held in position by a safety spring 21 having its outer and seated against a cylinder cap 28 which is bolted to the main casting. The gas discharged under compression travels downward-through discharge passage 28 in the main casting which connects with discharge passage 30 aligned therewith in the bottom casting l2 and which opens into an annular discharge chamber 3| substantially surrounding the bottom casting l2. The chamber 3| opens into a discharge valve 32 which is adapted to be connected to the discharge pipe (not shown) leading to the refrigerating system to which the compressor may be connected. Complete details of a piston and valve assembly of the type having the operating characteristics of the valve assembly disclosed herein may be found in my prior Patent No. 2,137,965.

In the preferred form of the invention the compressor is adapted to be suspended from a resilient biscuit 35 carrying a mounting member 3 as disclosed in my prior Patent No. 2,204,510; The biscuitr35 is bonded to a sleeve 31 through which may be slipped a bolt 38 adapted to be threaded into a boss in the top casting II. The biscuit 35 may thus sustain the weight or the compressor when the mounting member 36 is attached to a suitable supporting framework.

' compressor.

The compressor may thus oscillate in all directions and the biscuit will eliminate vibration and noise transmission. The top casting l i is preferably provided with a plurality of annular fins 40 which increase the heat transmission factor of the casing to aid in the elimination of the heat of friction and compression The top casting H is so shaped as to provide means to receive an annular sleeve 4! supporting the stator 42 of the driving motor. The rotor 43 of the motor is attached to the end of the shaft i6 extending above the journal 19. Convenience of assembly is thus provided since the stator may be mounted in the detached top casting ii and the assembly slipped into place over the rotor assembled on the, crankshaft. The casting H and the sleeve ll are preferably shaped to provide an annular oil receiving space 55 through which a stream of oil may be passed to carry away the heat generated by the motor. The windings of the stator are connected through leads #5 to slip connectors 36 mounted in a connector plate ll fastened over an opening in the main casting 10. The slip connectors are fastened to bolts 48' extending through the plate 47 and to the outer ends of which the power lines may be fastened. It is contemplated that a plurality of bolts 48 and slip connectors 45 will be provided in a standard connector plate 371. In the example illustrated, I have shown nine such members so that any known type of motor may be used by connecting leads in certain manners.

to the power lines as is well-known to the skilled electrician.

The bottom casting I2 is provided with a space 5!: providing an oil sump, the oil contained therein forming a reservoir from which lubricating and cooling oil may be drawn. The oil level preferably extends above the bottom of the asso ciated main casting In to the point indicated in Fig. 1, although the level may fluctuate within wide limits without affecting the operation of the A centralstandard 5! is cast integrally with the casting l2 and provides a base for a. pump housing 52 which has cast integrally therein an upstanding crescent shaped land 53. A runner gear 54 surrounds the land 53 and is provided with vertical teeth 55 (Fig. 4) between which are oil receiving pockets 56. The teeth are adapted to mesh with the teeth of an idler gear 51 mounted upon a post supported in the pump housing 52. The housing 52 is provided at one side with an elongated suction pocket 6| to which is' connected an elbow 62 carrying a suction tube 63 extending well below the oil level. At the opposite side the bottom of the pump housing 52 is provided with an elongated discharge pocket 64 having a drain opening ex tending into a discharge cavity 65 provided by the solid rim of the housing 52, the bottom s"rface of the housing 52, and the top surface of the pump standard 5|. The runner gear 54 is connected to a drive shaft 68 through which extends a horizontal driving bar 61 adapted to be engaged by a vertical driving pin 68 extending from the end of the crank pin l5.

When the motor drives the crankshaft the runner gear 54 is rotated and the gear pockets 55 are successively brought adjacent the suction pocket 6!. Oil which is thus placed in the pockets 56 is carried around between the outer wall of the crescent 53 and the inner wall of the pump housing 52 until it is deposited in the discharge pocket Bl by the compressing action of the teeth of the idler gear 51. When the gear pressure and in greater asoasu pockets 8 8 commence to open up again they have I passed beyond the limits of the discharge pocket 64 and are thus placed under suction so that when they again reachthesuction pocket 6| oil will be drawn from thesump. The oil is discharged into the space 65 under considerable quantity than needed rorlubricatiomi The Oil leaves the discharge space 55 through.

a passage I drilled vertically through the standard and which connects with a substantially oil receiving space 44 surrounding the stator of the motor. The opposite side of the space 44 communicates with a downwardly extending passage I6 which communicates with an alignedpassage II in the main casting III. A horizontal passage I8 drilled through an arm 80 supporting the journal I9 intersects vertical passage I1 and transmits oil into an annular space 8I surrounding the shaft I6 between the inner ends of the bearings I1 and I8. Oil is also transmitted through openings drilled through the shaft I0 (not shown) to the spaces between the connecting rods I4 as disclosed in my prior Patent No. 2,247,449.

' Passage 11 also communicates with a horizontalpassage 85 in arm 80 within which is mounted a pressure relief valve 86 operating against a spring 81 in the inner end of the passage and an abutment provided by the narrow elongated end 88 of the plug 88 closing the outer end of the,

passage. The pressure relief valve 86 is provided with an opening 80 through which any-oil may drain and flow through a drainage opening 9i so as to prevent leakage from trapping the piston against operationr-The strength of the spring 81 is designed to maintain a desirable pressure, such as'40 pound to 50 pounds, in the lubricating system. When the spring 81 has been'compressed due to the application of the desired pressure, the outer head of the valve '86 uncovers a vertical passage '82 drilled through the wall of the main casting I0 to a point closely adjacent the oil level line, the oil escaping therefrom being thus deposited in the sump without undue agitation and foaming. Oil which escapes from between the connecting rods and through the drainage opening 8| likewise flows down into the sump. Oil escaping from above the bearing I8 drains into the sump from a collector cup 83.

The annular space 8| communicates with a horizontal passage 05 drilled into a second arm 08 supporting the journal I8. This arm 06 isv oi large diameter and is provided with a cylindrical pocket 81 within which is slida'bly guided a sarting unloader piston 88. The outer, end of the cylinder pocket 81 is capped by a plug 99 through which extends'a passage I00 communicating with a longitudinal passage. l0l, in which is placed a starting-unloader valve I02. The valve is provided with a triangular stem passage IOI. Inward movement of the valve I02 is limited by an abutment member I04 supported in the starting unloader piston 88. A spring I05 surrounds the abutment member I04 and tends to keep the piston 98 retracted. as shown in Fig. 1.

When oil pressure is applied to the inner end of piston 88 the spring may be compressed, and the abutment I04 may cause the head of valve I02 to seat in the conical seat I03 thus blockin communication between the passage I00 and the space surrounding the abutment I04, which 1 space communicates with the interior of the casing through a gas return opening I06. The passage I00 is in communication with a passage I01 extending to one ofthe openings I3 which is in communication with the discharge chamber 3|, so that when the valve I02 is open the compressed gas will be released through the gas return opening I06 and the gas will expand back into the interior of the casing. The gas escapes from the portion of the casing enclosing the motor through openings I08 between the arms 80 and 96 (Fig. l) and is returned to the suction chamber 22 through openings such as opening I09 adjacent the lower bearing I! and oil drain H0 in the bottom of the suction chamber.

Thus, as long as the valve I02 is open the compressor will do substantially no work since the 'gas will be discharged against the suction pressure existing in the suction chamber 22, instead of against the discharge pressure established by the resistance of the refrigeration system. The valve I02 will be closed as soon as the pump has established sufiicient oil pressure to move the piston 98 toward the valve I02. In this manner it is made possible to use-low starting torque motors which are economical in power consumpolutions of the rotor have been made to permit the flywheel effect of the rotor and associated mechanism to overcomev the load of compression and'inertia.

The inner end of the passage II extending through the boss I2 connects at right angles to which provides three longitudinal passa es bea horizontal passage H5 extending into a cylindrical pocket IIG bored through a boss III connecting the base of the pump standard SI and the wall of the bottom casting I 2 opposite the discharge valve 82. The pocket H6 seats a cylindrical master valve body 8 which is held in place by sealing cap H8. The master valve body has a recess I20 therein in communication with a passage I2I leading to a central bore I22 extending through the valve body I I8. The central b'ore I22 is in communication witha bore I28 extending through the base of the pump standard 5| into the oil sump 50. The central bore I22 supports and guides a longitudinally .movable master valve rod I24 which is provided with a land I 25 shutting'ofl normal communication between the passage I2I and the bore I23,

.and a secondland I26 shutting off normal comrooves I21 which are adapted to receive a Spring The master valve'rod I24 is 1 mod ball I28. adapted to be moved longitudinally of the bore J22. and the purpose of the grooves I21 and spring urged ball I28 is to provide resistance causing the valve rod to move quickly by short steps rather than slowly by uneven amounts,

Movement of the valve rod I24 is accomplished by a master valve operator I30 including a flexible metallic bellows I3I projecting into the space 50 within the bottom casting I2 and retained in position by a sealing cap I32. The end plate I33 tending from the cap I32. The member I35 is retained in position by a nut I37 and lock nut I38.

The inner end of the bellows BI is fastened to a plunger I40 which is slidably guided in a bore I41 through the pump standard i. A locking rod I42 is also fastened to the plunger I40 and is threaded 'at its exterior end, which projects through the member I36, to receive a locking nut I43 which is adapted to bear against the end of member I35 when the rod I40 is locked against movement by drawing the end plate I33 tightly up against the end of a sleeve I 44 disposed within the bellows I31.

When the locking nut I43 is loosened, as shown in Fig. 1, the end plate I33 is free to move inward ly from the inner end of a spacer sleeve I44 as permitted by the balance of pressures between the suction pressure existing within the crankcase on one side and the combined efiect of the atmospheric pressure and the expanding strength of sprin I34 on the other side. As thesuction pressure decreases, inward movement of the rod I40 is accomplished to 'an extent such as to cause the force of the spring I34, lessened due to its expansion, practically to balance the outward thrust; As the suction pressure increases, the spring I34 is compressed until the end plate I33 strikes the inner end of sleeve I44. Movement of the bellows may be accomplished within difierent ranges of suction pressures by adjustment of the spring adjusting member I35 longitudinally oi the member I36.

Further details or the master valve operator may be ascertained from my prior Patent No. 2,185,473.

The plunger I40 is pivotally connected to a pair of rocking levers I50 mounted upon a rockshaft I5I supported in trunnions I52 carried by a pedestal I53 cast integrally with the pump base 5|. The lower arms of the levers I50are longer than the upper arms and are pivotally connected to the inner extremity of the master valve rod I 24 so that movement of the bellows I 3| is transmitted to a multiplied extent to the master valverod I 24. Movement .of the bellows I3I would normally be radual but the action ofthe grooves I27 and ball I28 causes movement of the bellows and of the master valve rod in spaced steps equal to the extent of one of the grooves I27.

As seen more clearly in-Figs. 1 and 5, the master valve body H8 is provided with a plurality of longitudinal bores I60 corresponding to the number of cylinders carried by the compressor and the number of grooves I27 in the master valve rod. The bores I60 are adapted to be aligned with a plurality of bores I6I drilled partially through the pump base 5I. Each of the bores I60 communicates with the bore I22 in the master valve body through a slot I62 cut; through the master valve body H8. The slots I62 are spaced longitudinally of the master valve body a distance substantially equal to the width of the land I25 or the distance between centers of the grooves I27 so that movement of the master valve rod I24 from one position to another places one or more of the slots I62 in communication with the space 65 into which oil is discharged by the pressure pump.

Each of the bores I6I is in communication with a connecting bore I63 extending upwardly through a vertical boss I64 cast integrally with the bottom casting I2 and rising toward the top of the casting, there being a plurality of such bosses equal in number to the number of cylinders of the compressor, and each of such bosses being associated with one of the cylinders. The upper end of each boss I64 is provided with an open ended cylindrical bore I 65 in which is loosely mounted a piston I66. The piston is adapted to bear against the lower end of an individual cylinder unloading plunger I67 extending through a vertical bore drilled through the wall of the suc tion space 22 beneath the centerline of the cylinder. A spring I68 surrounding the plunger it? tends to urge the piston I66 toward the bottom of the bore I65, the lower end of the spring being held by a snap rin I 69 mounted on the lower end of the plunger I67. Oil pressure transmitted to the cylindrical bore I65 through the action of the master valve rod I24 causes compression of the spring and vertical movement of the plunger 567. In Fig. 1 the first of the slots I62 has been connected to the pump so that the piston I66 at the rightside of the view h s been raised by oil pressure. The other three slots I62 are still beyond the land I25 so that the piston I 66 at the left side of the view has been lowered by expansion of spring I68.

The plunger I67 is pivotally connected to a yoke I75 having its arms embracing the cylinder sleeve 2I in which the piston 20 operates. Each arm of the yoke carries a floating pin' I76, one end of which rests upon a ramp I77 and the other end of which engages an unloader ring I78 surrounding sleeve 2|. The unloader ring I78 carries a plurality of pins I79 extending longitudinally of the outer surface of the cylinder sleeve 2| and the outer ends of which are adapted to engage the suction valve 23, as illustrated in the cylinder at the left side of Fig. 1, when the yoke has been retracted by expansionof spring I68. When the yoke I75 is advanced, as shown in the cylinder at the right. side of Fig. 1, the pin I76 has slid' down the ramp I77 thereby permitting the normal operation of the suction valve 23. The ring I78 and the pins I79 may float in this position or may be held in retracted position by any suitable spring device (not shown). Such a spring device is illustrated in my aforesaid Patent No. 2,185,473.

When the suction valve 23 of a single cylinder is held in open position, no work will be accomplished by that piston since the gas will enter the cylindrical space through the suction valve on the retraction stroke of the piston and then be forced back into the suction space 22 through the open suction valve 23 on the extension stroke of the piston. When the yoke I75 is extended, normal operation of the suction valve 23 permits that cylinder-to accomplish the work of compression. The cycle then is as dollows: On the the piston starts to retract, the discharge valve I M will close, partially due to the difference in pressures thus established and partially due to the operation of springs such as spring ISI.

As the pressure in the suction space 22 tends to vary, the number of cylinders in operation may vary so that the compressor tends to run 5- constantly and thus maintain a supply of refrigerant sufiicient to balance the load on the refrigerating system, rather thanto cycle on and off causing wide fluctuations in temperature.

In a compressor put to air conditioning use,

the spring I34 of the master valve. operator may be set to start moving the master valve rod when the suction pressure drops to 42 pounds. In the example illustrated in Fig- 1, this would cause suflicient movement to cause unloading of the 25 individual cylinder at the right or the view. The force of the spring maybe such that, as soon as the suction pressure drops another two pounds, a second cylinder would be unloaded and all cylinders would be momentarily unloaded when the suction pressure dropped to 36 pounds. However, the suction pressure would immediately rise, causing one or more cylinders to begin operating again. Selection of refrigerating systems substantially balanced against the capacity 5 of the compressor would thus permit practically constant operation of the refrigerating system tending to maintain a constantly proper output of conditioned air.

In other applications, such as the storage of 40 meat, a weaker spring may be used orthe same spring with-proper adjustment ofthe member I35 may permit operation of the master valve within ranges of, for example, 10 above zero to 10 below zero in increments of.5';for.each

cylinder. A wide range of applications is thus made possible with but a simple adjustment and a wide range of uses can be accommodated by the same type of. apparatus. Likewise, a wide range of variance in the calculations of the installation engineer may be accommodated since -the compressor will always attempt to balance against the refrigeration system; whereas, in prior practices if the refrigerating system were of too small capacity the compressor would only run intermittently for short periods of time.

A further advantage of the present invention resides in the fact that afsingle multiple cylinder compressor may be used in installations where 'a plurality of separate compressors were formerly 10- employed. Such would be-the case in meat, fruit, vegetable or fur storage rooms where a large increase in load might he suddenly applied in a refrigerating system as by the introduction of a large supply of fresh meat into the refrigerator '65 box. If the refrigerating system were supplied with refrigerant by a plurality of compressors connected in tandem and each controlled by a thermostat, the. sudden increase in load would cause all of the compressors to operate until the ,7

suction pressure had been drawn down to such a point as to caus'ethe usually supplied suction pressure safety cutout to operate on one machine. This would cause the one machine to stop with a resulting sudden increasein subbeen observed where the cycling .of such a. ma-

chine would occur every ten, fllfteen, oi perhaps thirty seconds. The strain on the compressor, and particularly upon the driving motor, commcnly results in failure of the mechanism which would leave an insufficient number of compressors in operation to draw down the temperature, with the resulting loss of the commodity intended to be refrigerated. A single compressor employing myinvention will overcome all these difllculties since the compressorwould be selected to be capable of balancing a. reirigerating system having a capacity great enough totake care of the maximum load which would be imposed, and the single compressor would draw down the temperature on a continuous smooth curve until a point might be reached where a single cylinder:

would be sufficient to maintain the normalheat leakage. An advantage flowing from this is that the power consumption would be substantially proportioned to the number of cylinders in operation which is materially less than the power consumption required by a standard compressor.

cycling on and off to maintain the desired conditions.

The starting unloader piston 98 cooperates with the individual cylinder unloading mechanism as follows: when a compressor has come to rest,

temperature in the refrigerated or air conditioned space causes the motor to start operating with the result that oil pressure is rapidly built up resulting inrapid closing of the unloader valve I02. .While the compressor was at rest the pressure existing in the interior of the crankcase rose because of the release into the interior or the crankcase through escape passage I06 of a large amount of gas at high pressure thus causing compression of the bellows l3! and connection of all the slots I62 to the space 65 before the compressor started operating. Therefore, as soon as oil pressure is supplied all of the yokes I15 will be extended to permit normal operation of the suction valves 23. Immediately all of the cylinders would commence drawing down the,suc-.

tionpressure until one or more of the cylinders would be unloaded by operation of the master valve. The compressor would continue operating under control of the master valve I30 until such.

time as the thermostat in the space caused the motor to stop. It can be seen from the above humidostat', or conceivably in accordance with torque against a low discharge pressure while the individual cylinder unloading means assures constant balancing ofthe output against the load.

.ingsto a suflicient extent; hence, as shown in that the controls required for an air conditioning or refrigerating system are reduced to thebare" of a single thermostat, or a single It is conceivable thattne-nnsw on the to casting H would not be sufllcient to dissipate the heat of the motor andfriction ofthe bear? Fig. 2, the end of passage ll may be opened by removing the plug I90, and oil permitted to flow through a cooling device such as a tube I! having fins I 92. This cooled oil would enter the space 44 '-surrounding the stator through a passage I83 normally closed by a plug 94.

The present invention permits the use of either a motor sealed in the casing as shown in Figs. 1 and 2, or of an external motor (or other driving means) as shown in F18. 8. It is dangerous, if not impossible, to use a direct current motor sealed into the casing since some refrigerants break down under the arcing of a direct current motor, or slow operation through gears or belts member 20! having frictional engagement with a fixed seal member 202. The member 20! is rotated with the shaft by the force of a spring 203 transmitted through a sealing gasket 2.

The fixed sealing member 202 rests upon a fixed sealing gasket 205. The projecting end of the shaft may be fastened through a coupling device 206 of any suitable character to the shaft 201 of a motor 208 mounted upon a bracket 208 extending from the end of the casting 206. In this form of the invention the upper ends of the oil passage l4 and the oil passage ll are preferably blocked by plugs 2m and 2! 1, respectively, although a solid gasket in place of the perforated gasket normally used may be sufiicient. In this case the normal flow of oil would be maintained by bringing the end of the oil cooler tube [9! into a fitting '2! occupying the place of the plug 2l6 (Fig. 2)

normally used to block the end of passage 18.

A further change found desirable would be the provision of a threaded'bore 2!! through the arm 80 into the passage 18 into which would be screwed a 1i g 2l8 carrying a. short length of tubing 2|9 having its upper extremity flattened and bent over to direct a stream of oil into contact with the frictional surfaces of the shaft seal.

The oil thus released to cool the seal would flow back into the oil sump 50 through the opening "18 (Fig. 1) All other parts and the functioning of each part of the compressor would be the same as explained in connection with the sealed compressor of Fig. 1.

Having described and illustrated preferred embodiments of my invention, it should be apparent to those skilled in the art that the same permits of various modifications in arrangement and detail. All such modifications as come within the ative upon cessation. of movement of said craniaber below desired limits to render individual sets of pistons and cylinders and the valves associated therewithinellective to discharge compressed gas into said discharge chamber even though said crankshaft continues to reciprocate all of said pistons.

2. A refrigerant compressor comprising a plurality of sets of compressing pistons anc. cylinders,

suction valve means and discharge valve means associated with each of said sets, a crankshaft drivingly connected to all of said pistons, a com mon suction chamber adapted to be connected with each of said cylinders through one of said suction valve means respectively and a common discharge chamber adapted to be connected with each of said cylinders through one of said discharge valve means respectively during the compression cycle, starting unloader means operative upon cessation of movement of said crankshaft and pistons to connect said suction chamber with said discharge chamber whereby to cause reduction in the pressure against which said pistons operate upon starting movement, means for disestablishing the connection through said starting unloader means soon after commencement of movement of said pistons, and individual cylinder unloading means associated with each of said sets of pistons and cylinders responsive to lessening of pressure in said suction chamber to suc= scope of the following claims are considered a part V of my invention.

I claim:

1. A refrigerant compressor comprising a pinrality of sets of compressing pistons and cylinders suction valve means and discharge valve means associated with each of said sets, a crankshaft drivingly connected to all of said pistons, a common suction chamber adapted to be connected with each of said cylinders through one of said suction valve means respectively and a common discharge chamber adapted to be connected with each of said cylinders through one of said discharge valve means respectively during the compression cycle, starting unloader means opercessive predetermined pressures to render individual sets of pistons and cylinders successively in effective to discharge compressed gas into said discharge chamber even though said crankshaft continues to reciprocate all of said pistons.

3. A refrigerant compressor comprising a plurality of sets of compressing pistons and cylinders, suctionvalve means and discharge valve means associated with each of said sets, a crankshaft drivingly connected to all of said pistons, 11 common suction chamber adapted to be connected with each of said cylinders through one of said suction valve means respectively and a common discharge chamber adapted to be connected with each of said cylinders through one of said discharge valve means respectively during the compression cycle, starting unloader means operative upon cessation of movement of said crankshaft and pistons to connect said suction chamber with said discharge chamber whereby to cause reduction in the pressure against which said pistons operate u'pon starting movement, means for disestablishing the connection through said start. ing unloader means soon after commencement of movement of said pistons, and individual cylinder unloading means associated with each of said sets of pistons and cylinders responsive to lessening of pressure in said suction chamber to sue-- cessive predetermined pressures to render individual suction valve means ineffective to operate in normal compression cycle fashion whereby individual pistons and cylinders become unable to compress refrigerant even though said crankshaft continues to reciprocate all of said pistons.

4. A refrigerant compressorcomprising a picrality of sets of compressing pistons and cylinders, suction valve means and discharge valve means associated with each of said sets, a crank shaft 'drivingly connected to all of said pistons, a common suction chamber adapted to be connected with each of said cylinders through one of said suction valve means respectively and a chamber with said discharge chamber whereby to cause reductionin the pressure against which said pistons operate upon starting movement,

- vidual unloading means is established upon asshiftably carried by the casting carrying said compressing elements and actuating parts shift-- ably carried by the other of said castings in such positions that cooperative relationship of the actuating and actuated parts of all of said indisembly-of said castings.

'7, A compressor comprising a single crankshaft and a plurality of compressing elements driven thereby, a housing comprising two separable cast- "ings, one of which carries said compressing elemeans for disestablishing the connection through said starting unloader means soon after commencement-of movement of said pistons, and individual cylinder unloading means associated with each of said sets of pistons and cylinders responsive to lessening of pressure in said suction chamber to" successive predetermined pressures to render individual suction valve means ineffective to operate in normal compression cycle fashion whereby individual pistons and cylinders become unable to compress refrigerant even though said crankshaft continues to reciprocate all of said pistons, such action. being accomplished successively with respect to each set of cylinders and pistons asthe suction pressure arrives at successively lower predetermined points.

5. A refrigerant compressor comprising a plurality of sets of compressing pistons and cylinders, suction valve means and discharge valve means associated with each of said sets, a crankshaft drivingly connected to all of said pistons,

a common suction chamber adapted to be connected with each of said cylinders through one of said suction valve means respectively and a common discharge chamber adapted to be con nected with each of said cylinders through one of said'discharge valve means respectively during the compression cycle, starting unloader means operative upon cessation of movement of said crankshaft and pistons to connect said suction chamber *th said discharge chamber whereby to cause reduction in the pressure against which said pistons operate upon starting movement, means for disestablishing the connection through said starting unloader means soon'after'commencement of movement of said pistons, and individual cylinder unloading means including an element responsive to lessening of pressure in said suction chamber below desired limits to render individual sets of pistons and cylinders and the valves associated therewith ineffective to discharge compressed gas into said discharge chamher even though said crankshaft continues to reciprocate all of said pistons, said pressure responsive element being responsive to an increase of pressure in said suction chamber resulting from connection of the latter with said discharge chamber by said action of said starting unloader means for presetting said individual cylinder unloading means in readiness to render said individual sets of pistons and cylinders and valves effective upon commencement of crankshaft movement.

. 6. A compressor comprising a single crankshaft and a plurality of compressing elements driven thereby, a housing comprising two separable castings, one'of which carries said compressing elements, and unloading means assoments, and unloading means associated with each of saidcompressing elements, each of said means comprising a suction valve lifting mechanism shiftably carried by the casting carrying said compressing elements and a suction valve lifting mechanism actuating piston shiftably carried by the other of said castings in such positions that cooperative relationship of the SUC? tion valve lifting mechanisms and the actuating pistons therefor of all of said individual cylinder unloading means is established upon assembly of said castings.

8'. A compressor comprising a 'single crankshaft and a plurality of compressing elements driven thereby, a housing comprising two separable castings, one of which carries said compressing elements, unloading means associated with each of said compressing elements, each of said means comprising a suction valve lifting mechanism having a shiftable element carried by the casting carrying said compressing elements and a suction valve lifting mechanism actuating piston shiftably carried by the other of said castings in such positions that contacting cooperative relationship of-the shiftable element of said suction valve lifting mechanisms and the actuating pistons therefor of all of said individual cylinder unloading means is estab- 40 lished upon assembly of said castings, a fluid pump carried by said other casting, and master valve means'within said housing'for selectively directing fluid; from said pump against one or more of said actuating pistons.

9. A compressor comprising a single crankshaft and a plurality of compressing elements driven thereby, a housing comprising two separable castings, one'of which carries said compressing elements, unloading means associated with each of said compressing elements, each of said means comprising a suction valve lifting mechanism having ashiftable element carried by the casting carrying said compressing elements and a suction valve lifting mechanism actuating piston shlftably carried by the other of said castings in such positions that contacting cooperative relationship of the shiftable element of said suction valve lifting mechanisms and the actuating pistons therefor of-all of saidindividual cylinder unloading means is established upon assembly of said castings, a fluid pump carried by said other casting, master valve means within said housing for selectively directing fluid from said pump against one or more of said actuating pistons, and a. master valve operator comprising a pressure collapsible part subjected to the pressure existing in a portionof said housing and opera- 4 tively associated with said master valve means.

ciated with -each of said compressing elements,

a 10. A compressor comprising a single crankshaft and a plurality of compressing elements driven thereby, ahousing comprising two separable castings, one of which carries said compressing elements,, unloading means associated with each of said compressing elements, each of said means comprising a suction valve lifting the outer end castings are united to piston, cylinder, sd

by the casting carrying said compressing elements and a suction valve lifting mechanism actuating piston shiftably carried by the other of said castings in such positions that cooperative relationship of the shiftable element of said suction valve lifting mechanisms and the actuating pistons therefor of all of said individual cylinder unloading means is established upon assembly of said castings, a fluid pump carried by said other casting, master valve means within said housing for selectively directing fluid from said pump against one or more of said actuating pistons, and a master valve operator comprising a pressure collapsible part subjected to the pressure existing in a portion of said housing and operatively associated with said master valve means to move said master valve means influicl connecting direction and adjustable spring means in opposition to said pressure collapsible part to move said master valve means in fluid disconnecting direction.

11. A compressor comprising a housing adapted to be sealed against said housing comprising a separable main casting and a bell-shaped casting, compressing mechanism carried by said main casting and includin a drive shaft having a free end projecting from the end of said main casting to which said end casting is attachable, drive shaft bearing means forming a integral assembly with said main casting, said main casting having its end surface lying substantially in the same plane as of said bearing means, an electromotive rotor mounted on said free end of the drive shaft, and an electromotive stator mounted on the inside surface of said bell-shaped end casting in position to surround said rotor when said complete th 12. A refrigerant compresses rality of compressing .its

charge valve meat? nected to ens, a common suction chamber a r be connected with each of said cyiind s through the suction valve means thereof, a n discharge chamber adapted to be connected ith each of said cylinders through (5153 discharge valve means thereof during the compression cycle, an individual cylinder unload ing system including an element responsive to decreasingand increasin of the pressure in said suction chamber with respect to desired limits to render said individual compressing units ineffective and eiiective respectively to discharge compressed gas into'said discharge chamber duringcontinuous reciprocation of said pistons, and a starting unloader system operative upon cessation of movement of said crankshaft and pistons to connect said suction chamber with said discharge chamber, whereby to cause reduction in the pressure against, which said pistons operate upon starting movement including means for disestablishing said connections after commencement of movement of said pistons.

13. A refrigerant compressor including a plurality of compressing units each comprising a piston, cylinder, suction valve means and discharge valve means, a crankshaft drivingly connected to all of said pistons, a common suction chamber adapted to be connected with each of said cylinders through the suction valve means thereof, a common discharge chamber adapted to be connected with each of said cylinders through the discharge valve means thereof during the comthe outside atmosphere,

2,869,841 mechanism having a shiftable element carried pression cycle, an individual cylinder unloading system including an element responsive to decreasing and increasing of the pressure in said suction chamber with respect to desired limits to render said individual compressing units ineifective and effective respectively to discharge compressed gas into said discharge chamber during continuous reciprocation of said pistons, and a starting unloader system operativeupon cessation of movement of said crankshaft and pistons to connect said suction chamber with said discharge chamber whereby to cause reduction in the pressure against which said pistons operate upon starting movement including means for disestablishing said connections after commencement of movement of said pistons, said pressure responsive element of said individual cylinder unloading system being responsive to an increase in suction pressure resulting from said connection of the latter with said discharge chamber by said action of said starting unloader system for presetting said individual cylinder unloading system in readiness to render said compressing units effective upon commencement of crankshaft movement.

14. A refrigerant compressor including a pressure lubricating system and a plurality of comtion of pressure of said lubricating system on said mechanism, a member responsive to decreasing and increasing of the pressure in said suction chamber with respect to desired limits for setting said valvemeans to actuate said mechanism to its unloading and loading positions respectively, a starting unloader system including valve means for establishing and disestablishing a. communicative connection between said suction and discharge chambers, and control mechanism for said starting unloader valve means including a member responsive to the pressure of said lubricating system for retaining said valve closed when said crankshaft is in motion and accommodating opening thereof when said crankshaft is at rest.

15. A refrigerant compressor including, a plurality of compressor units each comprising a piston, cylinder, suction valve means and discharge valve means, a crankshaft drivingly connected to all of said pistons, a. common suction chamber adapted to be connected with each of said cylinders through the suction valve means thereof, a common discharge chamber adapted to be connected with each of said cylinders through the discharge valve means thereof during the compression cycle, an auxiliary fluid pressure system including a pump drivingly connected with said crankshaft, mechanism associated with each of said compressing units and connected with said auxiliary fluid pressure system and responsive to the pressure thereof for individually unloading and loading said-units, shiftable valve means for r'essure in said suction chamber with respect to desired limits for setting said valve means to actuate said mechanism to unloading and loading positions respectively, a starting unloader system including valve means for establishingand disestablishing a communicative connection between said chambers. and control mechanismior said starting unloader valve means including a member responsive to the pressure of said auxiliary fluid pressure system for retaining said unloader valve means closed when said crankshaft is in 5 motion and accommodating opening thereof when said crankshaft is at rest.

' CHARLES R. NEESON.