US1896448A - Refrigerating apparatus - Google Patents

Description

Feb. 7, 1933. `A 1 KERCHER 1,896,448

REFRIGERAT ING APPARATUS FiledJan. 5, 192'/ 2 seets-sheet 1 FICE;

Feb. 7, 1933. y A 1 KERCHER 1,896,448

REFRIGERAT ING APPARATUS Filed Jan. 5, 1927 2 Sheets-Sheet 2 Patented Feb. 7; 1933 ARTHUR J. IKIERCBIIEB, OF BERKELEY, CALIFORNIA REFBIGERATING APPARATUS application inea January`l 5, 1927. serial No. 159,035.

This invention relates rgenerally to refrigerating apparatus of the type adapted for household use.

Asis well known in the art, l,refrigerating 5 systems usually employ an expansible fluid which is continuously passed through a ther'- modynamic cycle in order to absorb heat from the medium to be refrigerated. In this thermodynamic cycle the fluid is compressed, heat removed from it in a condenser or other suit- Y able exchange device, and is then-'expanded to absorb heat. In large installations it isa comparatively simple problem to provide satisfactory machinery for carrying out th1s cycle, but with small apparatus for household use, many diiiiculties are encountered. For exampleS the compressor and its driving motor must be practically noiseless/in operation. .The apparatus should be simple in construction so as to facilitate manufacture, should be etlicient in operation, and should require a minimum of servicing whenin' operation.

Because of the construction of the reciprocating compressors employed and the manner in which the motors and compressors are mounted, noise and vibration has made their operationv annoying even when cushioning means has been adopted. vFurthermore they must be frequently servicedbecause of mechanquently gets into the circulating system Aand interferes with its efficient operation. Another disadvantage has been that the several parts of the apparatus have, been segregated, thus limiting its adaptability. The high cost of manufacture however has probably bee1i)the 5 It is the further obj ect of this invention to ical imperfections and as lubricating oil fredevise a novel form of compressor for refrigerating 'l apparatus *whichl will combine ther `functions of a compressor and an oil separator.

Itis another object of this invention to devise a pump or Huid compressor which will have a minimum of parts, will not require expensive and ccurate maintaining and which will ther ore be cheap to manufacture. i

Another objectof this invention is to provide a novel form of electric motor for driv- `ing a refrigerating compressor which will be simple in construction and may be readily assemb1ed.

The'furt'her objects of this invention will appear from the following description in/ which I have set forth the` referred embodiment of my` invention. It) is to be understood that theI appended claims are to be ac- 70 corded a range of equivalents consistent with the state of the prior art.

Refer-ring to the drawings: Fig. 1 is a sideelevational view in cross section showing a refrigerating apparatus 75 embodying the principals of this invention. Fig. 2 is a cross sectional view taken along v the line 2-2 of Fig. 1 and showing the construction of the fluid co ressor.

Fig. 3 is a prospective view of the com res- 39 sor shaft showing the arrangement o the compressor ports. 1

Fig. 4 i's a diagrammatic view illustrating -the manner in which the actuator ring is magnetized to retain the compressor pistons. .L v

' This invention is chiefly concerned with the manner in which av uid compressor and condenser of a refrigerating system reicoprdinated ano with the structural details of the compressors whereby several new and im- 9 portant results are obtained. "The apparatus necessary for the usual thermodynamic cycle s consists generally of a iuid compressor 10 which delivers refrigerant fluid uden pressure tothe heat exchange device or condenser 95 11. After heat has been removed or dissipated from the iuid by passage through the condenser 11, the fluid is delivered to a heat absorber 12 of standard construction where the fiuid'is permitted to expand andJabsorb 10 ary central shaft about which .rotates a piston and cylinder assembly. However'many improvements have been embodied which render the compressor far cheaper to manufacture and more efective in use. Referring to the detailed construction illustrated, there is provided a stationary inner shaft 16 about which the cylinder member 17 is adapted to rotate. The cylinder member`17 is machined to provide a number of cylinder `bores`18 which are arranged substantially radial with respect to the center of shaft 16. In Fig. 2 of the drawings I have shown the-use of four cylinder bores, although of course it is evident that any number 'of bores may be employed depending upon the capacity desired for the compressor. Fitted Within the bores 18 are the pistons 19, these pistons being adapted to be reciprocated by means of an actuator` 20.

The actuator 20 is of novel construction in that no os1t1ve mechanical connection 1s .provided etween it and the pistons 19. It

1s constructed with an end plate 22 which is journaled to the shaft 16, as by means of the ball bearing assembly 23, this bearing being.

arranged so that. the actuator may revolve freely about an axis eccentric with the axis of rotation of tha cylinder member 17. Upon the rim of the end plate 22, there is a peripheral ring 24 having an inner periphery 25 which is ,preferably cylindrical in shape.

Each of the pistons 19 is preferably constructed hollow so as to be relatively light, and is provided with an outwardly bulged or curved end portion 26. The outer spherical surface 27'of end portion 26 forms an abutting engagement with the inner peripheral surface 25 of the ring 24. Ordinarily the centrifugal force of the rotating mass of the pistons is sufficient to retainthe pistons in abutting engagement with the ring 24. The eccentricity of theactuator introduces a slight amount of relative sliding movement between the pistons and ring 24, butbecause there is` a single point in contact between the Apistons, and the ring, the friction of this engagement will be slightI The abutting contact between the ,actuator and the pistons'is Iimportant not only in that Yit simplifies the mechanical construction of the compressor, but also in that it facilitates assembly and makes possible actual disalinement of the pistons without impairing in any way the operation of the compressor. In other words if in machining the cylinder bores 18, one or more of the bores are compressor cylinders.

ypins to an eccentric actuator, small inaccuracies in the alinement of the cylinder bores will make it diiiicult to assemble the compressor -I and will result in undue wear and noise when the compressor 1s 1n operation.

In certam mstances 1t 1s preferable to always retainthe pistons against the actuator ring 24 even when the compressor is at rest or moving relatively slow. This result may be accomplished by magnetizing the actuator as indicated diagrammatically in Fig. 4.

`Thus in magnetizing the actuator the rim of ring 24 is made either the north or south magnetic pole, and as the piston, cylinder member '17, and shaft 16 are all constructed of metal having .relatively high permeability,

the magnetic lines of force will occur as indicated. Thus the pistons will be magnetically retained against the inner peripheral surface 25 when the compressor is operated slowly or at rest.- As it is proposed to make 'the actuator-20V of relatively hard steel, it will retain its magnetism for an indefinite period.

The valves for yregulating the intake and .discharge of the compressor are preferably arranged in conjunction with the stationary shaft 16. Thus this shaft is provided with an enlarged valve portion 31 which is adapted to fit snugly within thecylinder member 17 Recessed within the periphery of this valve portion 31 there is an arcuate admission port 32, and another arcuate discharge port 33. The intake or admission port 32 communicates successively with a plurality of admission passages 34 provided in the cylinder member 17, these passages communicating with the fluid medium surrounding the compressors. For a purpose later to be described these passages 34 extendf outwardly or in a radial direction with respect to the axis of rotation of member 17 The discharge port 33 has permanent communication with the passages 35 and 36 in the shaft 16, passageway 36 leading to an external system of piping. Both the intake and discharge ports 32 and 33 are adapted to be alternately placed in communication with ports or passages 37 which communicate with the interior of the Additional means may be providedr for journaling the cylinder member 17 upon the shaft 16 in the form of a ball bearing assembly 38. This bearing assembly is preferably placed contiguous to one end of the valve-portion 31 so that it Will serve as a closure for one .end of the intake port 32. For convenience in manufacture it is preferable to extend this port to one end of valve member 31, instead of machining the same so that it will lie intermediate the ends of the valve member, as is necessary in case of the discharge port 33. To aid in malntaining a film of lubricant between the valve member 31 and the cylinder member 17, the e fes of ports 32 and 33 which lie in the direction of rotation of the cylinder member 17, preferably gradually merged into the peripheral surface of valve member .31 as indicated at 39.

The operation of the compressor involved may be better understood by reference to Fig. 2. Assuming that the piston and cylinder assembly is rotatedin counterclockwise direction, then actuator 20 also rotates about an axis eccentric to the axis of rotation of the piston and cylinder assembly so that the pistons will be reciprocated a, distance equal to 4twice the eccentricity. Taking first the cycle of one piston, say the piston shown at the bottom of the figure, as thispiston rotates counterclockwise about the shaft, it is moved outwardly by centrifugal force or by the magnetsm of the actuator and reaches the limit of its outward movement when in a position diametrically opposite to its original. position. During this outward movement of the piston fluid -is sucked into the cylinder through port 32 and one of passageways 34. However as the piston continues for the last .half of its movement, its passage 32 is placed in communication with disehargeport 33 and passages 35 and 36 so that as the piston is" again moved inwardly to the limit of its movement, fluid compressed below the piston is discharged through passage 36.

For reasons which will be presently apparent the compressor is preferably entirely enclosed within a housing 41, this housing also serving as a convenient means for mounting the stationary shaft 16. In so far as the lubrication of the compressor is concerned, this housing 41 makes it possibleto subject the external parts of the compressor to a spray of oil and to provide means for introducing oil into the compressor. In the bottom'of housing 41 there is a quantity of lubrieating oil 42 and the periphery of actuator 20 is provided with one or more lugs 43 which dip into this oil and thus splash and spray the same upon the external parts of the compressor. A certain amount of oil is also conf tinuously introduced into the compressor through passages provided in the stationary shaft plishing this result comprises a small reservoir 44 arrangedA near the upper portion of the housing in such a' position as Ato catch a certain amount of the oil sprayed by the lug 43. Oil from this reservoir is conducted by gravity through passage 46 and passages 47 and 48 in the shaft 16. From passage 48 y charged into the condenser.

16. A convenient means foraccom.

, and vibration,

oil may be conducted' to the bearing assembly 38 and by means" of passage 49 communicating with passage 47, is? conducted to the periphery of. valve member 31.6 A certain amount of the oil introduced through pas-7 sage 49 finds its way through Ipassages 37 into the cylinders and aids in sealing the pistons. Because of fthe separating ,action caused by the ra piston and cylin find its way into the passages 35 and 36 and thus will not become mixed with the fluid discharged from the compressor. Furthermore because of the radial position of intake passages 34 any oil which has become mixed with the fluid being drawn into the compressor, or any oil finding its way into passages 34 will be thrown outwardly by centrifugal force and thus prevented from being dis` The thorough manner in which the compressor is lubricated makes accurate and fine machinery unnecessary and permits the use of large tolerances without causing undue leakage, thus further cheapening the cost of manufacture.

The electric motor for driving the comprcsssor described above is preferably also in losed within housing 41 and incorporated V with the compressor as a motor compressor unit. Thus the housing 41 is constructed of two portions 51 and 52 removably secured together as by means of cap screws 53, the part 51 serving to inclosel the compressor and the part 52 -inclosing the electric motor. The compressor shaft 16 preferably. has one end' extended through and suitably mounted upon the end 54 of housing v i its other end extending through the housing portion 51 whereby external fitting 56 for connecting the con-` it may engage with an id rotary movement of the er assembly this oil will not portion 52, and has Y denser with the discharge passage 36." The motor rotor 57 is preferably journaled upon the shaft 16 as by means of a bly 58, and is preferably directly coupled to rotate the cylinder member 17, as by means a force fit within the `rotor 57 and the other bearing 'assem- 110 yof a coupling sleeve 59, one end of which has end being nonrota-tably secured to the'bylim der., member 17as bymeans of a ke'y 61. Bearing assembly 5/7 may be lubricated from -f the passage `48 by means of another passage 62. For simplicity the motor stator 63 has a forced or drive fit with the inner peripheral surface 64 of the housing portion 52. The windings of the motor are preferably im# pregnated with 4a suitable solid insulating compound which will not only minimize all alternating current hum but will also prevent anyinjurfy thereto by contact with the lubricating oil orthe refrigerant fluid.

y ile a compressor as described above will operatevwith avery Ismall amount'iof'noise employed with domestic refrigerating sys. tems, noise must be reduced to the point where such compressors are where it cannot b e detected even a few feet away from the compressor. Asaspecialfeature o rfrthis-invention 'itkis proposed to minimize transmission of noise by means of a liquid mass to which 'the motor and compressor are subjected. In practice this is accomplished by making the housing 41 fluid tight and then entirely submerging this housing in liquid such as water. Another feature of this invention is that the liquid which serves to minimize transmission of noise from the motor and compressor, also serves to transfer heat from the heat exchange device orcondenser 11. Thus both the motor compressor and the condenser 11V the compressor and the condenser are spaced from the walls of the receptacle 66 and are Iprovided with suitable cushioning mountings to prevent direct transmission ofvibrations to the walls of the receptacle'. One suitable form of cushioning mounting utilizes rubber blocks 71 which rest upon the bottom of the receptacle and which support the base plate 72 upon which the motor compressor unit and the condenser are supported. It is obvious however that in place of the rubber blocks I may employ resilient compression springs, or the motor compressor unit may be suspended by means of tensioning springs. The heat which is dissipated from the condenser and from the housing of the compressor, is absorbed b v the liquid 67 and transferred to the walls of the receptacle 66 both by convection and conduction. For dissipating this heat from the system the walls of the receptacle may be provided with cooling ribs or fins 73 to aid in transmitting the heat to the surrounding air.` As a supplemental or alternative method of keeping the liquid within the receptacle below a' certain temperature, a cool liquid may be introduced into the receptacle and the heated liquid continuously removed. For example there is shown a liquid intake pipe 74 and liquid removal pipe 76 adjacent the upper portion of the receptacle.

The liquid within the receptacle may always le maintained cool during operation of the compressor by continuously introducing cool water through pipe 7 4 and removing heated liquid through pipe 76, or cool liquid may:

only be introduced through pipe 74 when the heat transmitting surface of the receptacle is inadequate to dissipate the heat at a suicient rate to keep Y.the liquid cool.V VIf desired the *introduction of cold liquid into the receptacle may be controlled thermostatically so that cold'liquid is only circulated when the temperature of the surrounding air is toohigh to adequately carry away the heat of the liquid. For example I have indicated diagrammatically a thermostatically controlled switch 77 mounted in thermal contact with one wall of receptacle 66, and which` controls an electrically operated valve 78. The terminals of switch7 7 and valve 78 are connected to a common source of current such as lines L1 and L2. When the temperature in the receptacle rises to a value abovewhich efficient operation of the refrigerating plant is impaired, thermostatically controlled switch 7 7 is operated to open valve 78 and thus permit introduction of cool liquidV into the receptacle.

The top of the receptacle 60 has been shown as provided with a suitable cover 81 through which may extend the pipe connections to the compressor and condenser. The compressor intake pipe 82 which connectsthe absorber' to the compressor, communicates through one side of housing 42, a suitableconnection 83 being provided to prevent entrance of the liquid within the receptacle 66. The wires 84 for making electrical connections to the motor are preferably extended through a conduit 86 which extends up through cover 81 and is provided with a suitable terminal box 87.

In operation the liquid mass surrounding the compressor housing effectively deadens all noise and vibration and prevents all sound waves from being transmitted to the surrounding air. The heat generated from operation of the motor and by compressing the fluid inthe compressor, is transferred to f the lubricating oil 42 and to the compressor l motor housing 41 and thus transferred to liquid within the receptacle. This liquid also serves to remove heat from the fiuid in the condenser 11, all the heat removed from both the compressor and condenser is transferred to the walls of the receptacle, where it is dissipated by radiation-and by convection currents of air coming-into contact with the outer surfaces of the receptacle. The liquid within the receptacle may also be kept cool by introducing cold liquid through p ipe 74, or introduction of liquid through this pipe may be automatically controlled by the ther-- Amostat arrangement described above. As the. intakepassages34 of the compressor communicate directly with the interior of the compressor housing 41, the interior of the housing will always bemaintained at the intake pressure and all Huid leakage from compressor pistons and valve mechanism, will find its f way back into the compressor intake. As previously explained the compressor acts as a centrifugal oil separator so that when the compressed Huid reaches discharge passage .rotate the compressor backwards as a pneumatic motor until the pressure in the intake and discharge has become substantially equa/lized. l'Vhen the motor is again energized, it

Y starts at practically no load since several revolutions of the compressor are necessary to first build up a discharge pressure. This no load start is important since many of the alternating current motors available for refrigerators have a relatively low starting torque. After the compressor has been atrest for some time all of the oil will drain from reservoir 44. When the compressor is again started in operation, oil from lug 43 will not reach reservoir 44 until the compressor has attained a relatively high speed. In other words I have provided a pumping device for introducing oil into the compressor which is rendered practically inoperative unless the compressor speed is above a certain minimum value. Without this feature the centrifugal action of the moving parts of the compressor would be ineffective to remove all of the oil from the fluid refrigerant during starting of the compressor when the compressor` runs at a relatively low speed, with the result that oil would be carried over in the discharge passageway 36.

It is apparent that a variety of refrigerant fluids may be used with the refrigerating system described above. For example I may employ ammonia, sulphur dioxide, carbon dioxide, methyl-chloride, ethyl-chloride, or other such fluids, although because of its low pressure required for condensation, ethyl-chloride is the preferred fluid. It is obvious that the character of the refrigerant fluid employed will determine the capacity and discharge pressure of the fluid compressor. lVhen using ethyl-chloride it has been found essential that all oil be removed from the fluid before it is discharged into the condenser. With the apparatus as described above it has been found that ethyl-chloride may be successfully employed without the addition of a separate oil separator in the discharge of the compressor, the centrifugal action of the separator being suflicient to effect com plete oil separation.

I cla-im:

1. In a refrigerating system in which a refrigerant fluid is continuously circulated through a heat exchange device and a heat absorber, a compressor for circulating fluid through the heat exchange device and absorber, a receptacle Within which is mounted the compressor and heat exchange device, upstanding cooling fins formed upon the outer surface of the receptacle, and a liquid within the receptacle to minimize transmission of sound from the compressor and to transfer heat from the compressor and heat exchange device to the receptacle.

2. In a refrigerating system comprising a heat exchange device for removingheat from a refrigerant fluid, a heat absorber for permitting the expanded fluid to absorb heat from a medium to be cooled,a compressor for receiving expanded fluid from the heat absorber and delivering the compressed fluid to the heat exchange device, and a motor for driving the compressor, the combination of a sealed housing enclosing the motor and compressor, a receptacle forenclosing said housing, resilient means for supporting the housing Within the receptacle and in spaced relationship with all of the walls of the receptacle, and a liquid mass within the spa-ce between the housing and each wall of the receptacle for minimizing transmission of sound from the housing.

3. In a refrigerating systemin which a refrigerant fluid is continuously circulated through a heat exchange device and a heat absorber, by means of a motor driven fluid compressor; a unit consisting of a receptacle within which the heat exchange device is dis,- posed, a sealed housing for the motor and compressor also disposed Within the receptacle, resilient means for supporting the housing within the receptacle and in-spaced relationship with all of the Walls of the receptacle, and a liquid mass within the receptacle for transferring heat to the receptacle and for minimizing transmission of sound from kthe housing.

4. A fluid compressing unit comprising a fluid compressor, a motor for driving the compressor, a liquid-tight housing enclosing both said motor and said compressor, a receptacle. resilient means supporting said housing in spaced relationship with all of the walls of said receptacle, whereby transmission of vibration of the housing to the receptacle is precluded, and a mass of liquid disposed within the space between the housing and each wall of the receptacle, to miniv mize transmission of noise from the housing.

In testimony whereof, I have hereunto set

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