US2364038A - Hermetic refrigeration compressor - Google Patents

Description

J. TOUBORG 2,364,038

HERMETIC REFRIGERATION COMPRESSOR Filed Dec. 6, 1941 3 Sheets-Sheet?! Nov. 23 1944.

Nov. 28, 1944. R TQUBQRG 2,364,038

HERMETIC REFRIGERATION COMPRESSOR Filed Dec. 6, 1941' 5 Sheets-Sheet 3 INVENTCR 7912sv .Tbzgo y BY Patented Nov. 28, 1944 orrics HERMETIC REFRIGERATION oomnnsson Jens Touborg, Tecumseh, Mich. Application December 6, 1941, Serial No. 421,986

7 Claims.

1 This invention relates to hermetic compressors of the type applicable in a compression-condensing-expansion refrigeration system. It is particularly directed to improvements in such compressors, looking to the internal mounting of the mechanism, the effective dissipation of heat, and relief of the compressor and motor from injurious overloads and excessive starting torques, all of which improvements are coordinated with each other in a compact and inexpensive unit having a long service life.

The hermetic compressor is characterized by the disposition of the compressor and its driving motor within an impervious shell, into which the refrigerant may be inducted and from which the compressed vapor is withdrawn, without the employment of rotary seals. While this eliminates a source of leakage encountered in conventional units, the development of wholly acceptable hermetic compressors has been retarded by a number of special problems inherent in the fundamental of the design.

Inasmuch as the motor is directly, connected to the compressor shaft or connecting rod, starting cannot be effected under load, unless special types of motors, having a. high starting torque, are employed. The alternative is to provide an unloader device for the working chamber of the compressor, but, as heretofore proposed, such mechanisms have been open to a, series of objections. Again, the conventional compressor presents no serious problem of dissipation of motor heat. since the motor is exposed to the air, and circulation is more or less induced by the proxmity of the fan for the adja'cently located condenser. In 'the hermetic type, the motor is enclosed, and dissipation must be effected through the casing wall. Obviously, the heat must not accumulate, since it would thin down the oil in the casing, lower the volumetric emciency by overheating the vapor, and eventually burn out the motor.

In order to elim natesuch heat, it has been proposed to cool by means of extended fin surface, or by water Jackets, both of which are costly proposals, or to bring the motor into direct thermal contact with the shell wall. When this lost'named expedient is resorted to, the shell wall becomes the supporting frame for the motor compressor unit, or vice versa, and there are encountered alignment and machining problems, as well as a potential factor of noise. Hence, asa further corrective expedient, it .becomes necessary to' mount the casing on resilient supports, which are apt to be misplaced, because exposed, and which are also expensive.

In the present invention, proved engineering M methods, contributing to an efficient unit, are retained, but the motor and compressor are provided with a simple mechanical form of overload relief mechanism, designed to unload the compressor during starting or stopping periods, and thus eliminate the problems encountered otherwise. Further, the unit is internally mounted on resilient supports, so as to suspend the unit properly but also eliminate the external mountings heretofore used-and the motor is spaced from the shell wall, cooling being effected by a fan driven by the motor, and which. may be cooperatively assembled with the unloader de vice. A form which these improvements may take, and the advantages attending the use thereof, will be more apparent from a perusal of the following description of a preferred embodiment of the invention, illustrated in the accompanying drawings, wherein:

Fig. 1 is a vertical section, with parts shown in elevation, of the improved compressor, showing particularly the internal mounting;

Fig. 2 is a plan, taken on the line 2ii' of Fig. 1, the unloader control being omitted for simplification;

.Fig. 3 is an enlarged fragmentary section on v the line 3-3 of Fig. 2, particularly showing the unloader control and vapor fan; 7

Figs. 4, 5, and 6 are details of the unloader control and fan, taken on the section lines designated in the preceding view;

Fig. 7 is an enlargedfragmentary view, from the head end of the compressor, taken on the line 7-4 of Fig. 1;

Fig. 8 is a detail, taken on the line iB-8 of Fig. 3, and further illustrating the mounting of the unloader needle and lever arm; and,

Fig. 9 is a view taken on the line 9-,-9 of Fig. 8

Referring first Fig. 1, there is shown a hermetic compressor comprising an outer casing or two-part shell ii, an electric motor l2, and a compressor l3. The compressor includes a main casting having a cylinder block portion l4 formed with a cylinder bore IS, a horizontally disposed annular flange l6 formed with a main bearing l1, and an upstanding flange IS. The stator IQ of the motor I! is press fitted into the flange ,IB, and the motor shaft 2|, which, of course, is

and 23 is formed with a crank or eccentric 24, to which is connected the big end of a connecting rod 25, which extends to a piston 26 reciprocably disposed in the cylinder bore I5. The head end of the cylinder is provided with a valve plate 21 and a, head 28, which cooperate to admit and discharge refrigerant. -Referring also to Figs. 3 and '1, it will be seen that a partition wall 29 divides the head into an upper chamber 3| and a lower'chamber 32, respectively in communication with inlet valves 33 and outlet valves 34. The chamber 3| is drilled to receive an inlet pipe 35, provided with an oversize or muffler section 36. The other end of the pipe 35 is open to the upper end of the casing and, as will be understood, the suction line from the evaporator also communicates with the open upper portion of the casing. Returning refrigerant vapor, admitted to the 'upper portion of the casing! flows around the motor 12, as will the sleeve type mounting heretofore referred to are therefore solved.

In order to remove the appreciable quantities of heat which result from the running of the compressor, a fan or vapor stirrer 55 is positioned on the upper end of the rotor 22, The fan is formed from a sheet metal disc whose peripheral portion is slit and bent, as best shown in Figs. 3 and 4, to provide a number, of upstanding wings 56. The inner edges of the wings define a hexagonal structure, the purpose of which will be pointed out later. As the rotor revolves, the fan is I carried with it, and the wings direct the incom be more fully explained later, into the inlet pipe I 33, and thence to the chamber 3| and intothe cylinder l5, through the inlet valves 33.

ompressed refrigerant is discharged past the spring-loaded valves 34 into the discharge chamber 32, thence through a duct 31 into a discharge muffler chamber 38 formed in the casting, and finally to a discharge pipe 39 which is connected to the condenser in the usualmanner. It is deemed unnecessary to describe this structure, or the mode of operation, in greater detail, since the parts just referred to, except for the muffler 36, are not new with this application, and have been more fully set forth in my prior and 00-;

pending applications, Serial Nos. 327,063 and 35 332,973, now Patents Nos. 2,274,942 and 2,274,- 943, patented March 3, 1942, which, among other things, describe effective means for lubrication by the oil which is contained in the lower portion ill of the casing H.

Differing, however, from the compressors shown in the prior applications, it will be observed that the flange l8, which receives the stator I9, is not ing refrigerant vapor around the motor and to the Wall of the casing, thus employing the vapor as the heat transfer medium. Due to the cons-tant stirring action, enough heat is so transferred to prevent the motor and vapor from becoming overheated, and it has also been discovered that the eficiency is such, compared to similar size units as disclosed in my copending applications, as to maintain proper working temperatures without water cooling or extended fin surface.

The fan is positioned over the end of the rotor by means of two short spacer sleeves 51, and is secured by screws 58'extending therethrough into taps in the rotor, as best shown in Fig. 5. It will also be noticed that these screws hold other parts in postion, and that such other parts are disposed on the central portion of the fan 55, being located within the inner edges of the wings, which in effect constitute a retaining cage. These parts comprise a centrifugal mechanism, employed to control an unloader valve.

Referring particularly to Figs. 3 and '7 it will be noted that the valve plate 21 is-formed with a vertically disposed bore 6|, which is in communication with the' inlet chamber 3| through a port 40 62, and with the cylinder. l5 through a small (onein metallic contact with the upper portion of the shell II, but is widely spaced therefrom, and that the inlet pipe 35, instead of passing through the stator l9, extends into the clear space. In order to mount the compressor within the shell, the lower half I of the casing II is formed with three-circumferentially spaced indentations 4| providing plane pads 42. Connected to the under side of the casting flange I6 is a lug 43 (see Fig. 2) and an arcuate stirrup 44, which members are so spaced as to overlie the pads 42 when the motor and compressor unit are inserted in the shell. Each member is formed with an aperture 45 and a downwardly extending shoulder 46 at the overlying regions, to receive an upstanding bolt 41, secured to the pad 42, and an interposed compression spring 48, as best shown in Fig. 1.

A washer 49, placed over the bolt and on the pad. cooperates with the shoulder 46 to retain the spring 48 in position. The upper trace of the aperture 45 is covered with a washer 5|, on which is mounted an auxiliary spring 52, and which is compressed by a securing nut 53 threaded onto the end of the bolt 41. It will thus be seen that the whole working assembly is resilient- 1y mounted within the casing H, is spaced from sixteenth inch) hole 63. When this passageway is open, any vapor inducted into the cylinder |5 on the suction stroke of the piston 26 will flow back on compression, and the compressor will operate without performing any work, or it will be unloaded. On the other hand, if the passageway is closed, the vapor will be compressed, and discharged past the valves 34 in the normal manner. Theobject in providing the unloader mechanism is to protect the compressor and motor against great overloads, and to enable the motor to start under no load, and to come up to full speed (and thereby maximum torque) before being subjected to working load.

The means for closing the passageway comprises a needle valve 64, vertically disposed in the bore 6|, and biased to a valve closing position in the following manner. Mounted on the side of the casting flange I8 is a bracket 65, formed with a horizontal bearing portion 66, a vertical offset portion 61, and an overhanging stop portion 68. The portion 66 is formed with a square aperture 69 to receive a square shank 1|, tapped on its lower end toreceive the needle 64. When the parts are properly assembled and adjusted,

' the needle may be secured to the shank by applying a drop of solder to the connection.

The needle 64 and attached shank 1| are raised and lowered into valve opening or closing positions by a lever 12, one end of which overhangs the center. of the rotor 22 and the fan 55. The lever is formed at its opposite end with an offset section 13, engaging in a slot 14 formed in the vertical section 61 'of the bracket 65. The shank 1| is also formed with a lateral hole 15 to receive one end of a resilient-retaining wire 16,'the

opposite end of which is carried over the lever 12, and is positioned in an aperture 11 formed adjacent the offset section 13. When the parts are assembledcas shown in the drawings, the moment of the lever 12 causes it to drop down, and thereby depress the needle 64 by the force exerted on the upper end of the square shank 1 I ,as shown in Fig. 3. When the lever is raised, its engagement with the needle, through the wire 16, causes the needle to ;be lifted from its valve seat at the bottom of the bore 6|. This upward movement is limited by the stop portion 68, and engagement of the wire 16 with the flange 66.

It will thus be understood that the needle seeks a valve closing position, or one corresponding to a working condition in the compressor, at all times. This tendency can be overcome either by lifting the lever 12 against its free end, or by exerting suflicient pressurethrough the aperture 63. In view of the latter possibility, theilever I2 is made of such size and weight, with respect to the area '63, sure to dislodge the needle. In practice, this may be'set at say five hundred pounds, by adding a counterweight 78 on the free end of the lever.

If this pressure is exceeded, as it might be if the discharge line became jammed, the needle 64 will release from its'valve seat, and thus provide an overload protection device.

In this connection, attention may be invited to the fact that in the unloader herein described,

as to require a relatively high presthe relief is not effected by direct operation on either the inlet or discharge valves, but rather 1 it is effected by short circuiting the compressor to the inlet side through an auxiliary valve. This not only eliminates difliculties encountered with some of the earlier proposals, but also, by reason of the gravity or mechanical action of the control mechanism, permits of the utilization of the unloader passageway as a protective device both for the compressor and the motor. It will also be seen that, due to the guiding of the needle rod 54 and the formation of the lever 12, the bias towards closing position would also exist, even if the unit were turned on its side, for a horizontal mounting, as well as for the vertical mounting illustrated.

The centrifugal mechanism, heretofore referred to, is employed to lift the overhanging end of the lever 72 when the motor is operating below a predetermined speed, and thus unload the compressor during starting or stopping periods. In

Fig. 3, the parts are shown for a condition of full speed, while in Fig. 5 the parts are shown as they appear at zero or comparatively low speed. It may also be noted here that the mechanism is advantageously of the full mechanical type, and need not be dependent upon magnetic or electromagnetic principles, as are incorporated in some types of unloaders.

by forming the sleeve 99 disposed ribs 10], interrupted to provide the slots,

This device consists of a hexagonal base .8I,

provided with upstanding flanges 82 on two opposed sides, so dimensioned as to contact a number of the inner edges of the fan wings 56, as best shown in Figs. 3 and 4, thereby centering the unit on the fan. The center of the base 8| is formed with an aperture 83, around which is positioned a boss 84 that extends slightly above the upper surface of the plate. The base is drilled at diametrically opposed points, as previously explained, to receive the screws 58 employed to hold the unit and the fan in position. Each flange 82 is formed, at a lower corner, with a hole 85, and, at the opposite upper corner,

with a hooked finger 86 extending generallypar allel to the adjacent edge of the hexagonal base.

A centrifugally responsive member 81, provided at its lower edge with a lip 88 adapted to engage in the hole 85, is positioned adjacent each flange 82. This provides a pivoted connection, so that,

under the influence of centrifugal force, the member 81 will swing up into facial engagement with the flange 82, being further retained in pivotal movement by a struck-out second lip 89, which overlaps the edges of the base 8|. The upper edge of each member 81 is provided with a finger 9|, oppositely located to the finger 86 on the flange 82. Coiled springs 92 extend between the finger 86 of one flange, and the finger 9| of the opposed member 81, and these, of course, tend to pull the members 81 away from the: flanges, and. down against the base 8|.

As thus far described, there are therefore two opposed pivoted members, which tend to fly out under centrifugal action, and which are opposed in such tendency by springs interconnecting the members. The mass of the members, and the tension of the springs, are accordingly so proportioned as to permit the members to spread apart at full motor speed, but to be drawn together below a predetermined speed. Each member 87 low, thus depressing the extremities of the arms 96. Each lever arm 96 is formed with a boss 91, which engages one of a pair of slots 98, formed on a movable sleeve 99. These slots are made with a pair of axially as best shown in Fig. 3; Hence, as the levers are pulled down, they draw the sleeve 99 down with them, and, when the levers are raised by the spring action, the sleeve 99 moves up.

The counterweight 78, previously referred to as being disposed on the end of the lever 12, flts freely into the aperture of the sleeve 99, providing an additional safeguard against displacement of the parts. In Fig. 5, 'the centrifugal unit is shown as being in its collapsed position, and it will be seen that the sleeve 99 has lifted,

to elevate the end of the lever 12, and thereby '26 will be under an unloaded condition, since any inducted refrigerant vapor will be returned to the inlet chamber 3i. As the motor comes up to speed, centrifugal force will act on the control mechanism, causing the sleeve 99 to drop down, as shown in Fig. 3. The lever 12 can thus drop under the force of gravity, to close the relief passageway, load.

It will benoted, in Fig. 3, that under operating conditions, the sleeve 99 is. sufficiently depressed to be out of contact with the lever, the lower limit of the lever being determinedby the engagement of the needle 64 on its seat. Constant running engagement, with'the attendant effect of wear, is thus avoided. When the motor is shut down, the sleeve 99 again lifts to open the valve 64, and thus unloads the compressor just before it comes to rest. This is an advantage, for it eliminates a tendency of the motor to reverse, under the compression in the cylinder l5, and

and the compressor will operate under aseaose predetermined pressure acting on said valve through said relief aperture.

anism and the spring mounting upon shutting down serves to eliminate a. little squeak which is i so frequently heard inapparatus of this nature. 'It may also be pointed out that as the needle valve is just cracked-that is, is just slightly off of its seat, during-starting and stopping periods, the velocity of the gas flowing through the port 6| may be such as to set up an undesirable noise. Themuffler section 36, disposed in the inlet line, overcomes this tendency.

It is believed that the purposes and functioning of the various parts have been sufficiently explained as the description has progressed, and restatement is therefore unnecessary. It is desired, however, to call attention to the circumstance that the unloader mechanism, the means for eliminat ing heat, and the internal mounting, have all been structurally and functionally coordinated to provide a compressor constituting an improvement on those heretofore known. While the invention, in 'the best embodiment now known to me, will therefore include all of these improve-' ments, it is also apparent that the invention may merous modifications and variations. Accordin ly, it is intended that thescope of the invention should not be restricted to the specific details, but v should be considered as commensurate with the import of the following claims.

I claim:

1. In a refrigeration compressor comprising a casting member having a cylinder bore and a piston, a motor mounted above the cylinder and operatively connected to the piston, a bracket mounted on the casting andextending upwardly thereof, a lever pivotally connected to the bracket at one end and overhanging the motor at its opposite end, whereby, due to the moment of the lever, it tends to drop on its pivot, centrifugal control means connected to the rotor of the motor, said control means, when the motor is below predetermined speed, contacting and elevating said lever, said means, when the rotor is above predetermined speed, being spacially released from the lever, a relief valve connected to the lever adjacent the pivot, a relief passageway communicating with the bore of the cylinder, said valve extending into the passageway and seating therein to close the same when the lever is'released.

2. In a refrigeration compressor, a casting including a cylinder and a piston in the cylinder, an upstanding flange on the casting, a motor stator mounted in the flange, a motor rotor mounted within'the stator'and operatively connected to the piston, a valve plate on the end of the cylinder, a relief aperture in the plate, a valve 3. In a refrigeration compressor having an unloader mechanism, an unloader control valve comprising a bracket member havin'g'e bearin portion and a pivot portion, an unbalanced lever mounted in the pivot portion, a control valve slidably mounted and guided in the bearing portion and having one end contacting the lever, and a retaining Wire engaging the valve below the bear;

ing portion and overlapping the lever.

4. A compressor unloader mechanism adapted]:

to be combined with a compressor having a work: ing chamber, a compression member, and a 'motor connected to the compression member, comprising a bracket formed with offset bearing and pivot portions, a needle having a rectilinear shank mounted in the bearing portion for sliding move ment therein, a lever having-an offset portion pivotally mounted in the pivot portion, said lever being of such length and mass as to overlie the motor for actuation thereby under predetermined operating conditions and to bias the movement of the needle, and a retaining wire interconnecting the shank and the lever, said wire having a portion connected to the shank below the bearing portion and an overlapping portion engaging the upper side of the lever and holding the end of the shank against the under Slde Of the lever.

5. In a refrigeration compressor including a casting formed with a cylinder, a piston in the cylinder, and a motor mounted on the casting above the cylinder and operatively connected to the piston, a fan secured to the rotor of the motor, said fan being formed with radially disposed upstanding wings, a centrifugally responsive control mechanism positioned within the wings and retained on the fan, a lever pivotaily mounted at one end on the casting and having its opposite end overhanging the control mechanism for actuation thereby, an unloader valve rod secured to the lever and extending adjacent the cylinder, said rod being operated through said lever to unload the compressor when the motor is below predetermined speed, resilient mounting means for the-compressor on said casting, a casing for the compressor and motor spaced therefrom and cooperating through said mounting means to support the casting, said centrifugal 7 transfer heat to and through the walls thereof.

mounted in the aperture to close the same, a

bracket on the flange, a lever mounted on the bracket and overhanging the rotor, said valve and tact and actuate the lever to open the valve, said lever having a moment suchas to be overcome by 6. A hermetic refrigeration compressor comprising a casing formed with indented wall portions, a casting within the casing and spaced from the walls thereof, resilient means interposed between the casting and the indented portions of the casing to support said casting, means for admitting refrigerant vapor to thecasing, a cylin der formed in the casting, a piston in the cylinder,

9. motor stator mounted on the casting, a rotor within the stator and rotatably mounted in the casting, said rotor being operatively connected to the piston, inlet and discharge valves for the cylinder, said inlet valve communicating with the casing to receive refrigerant vapors therein, a fan mounted on the rotor to transmit heat through the vapors to the wall of the casing, a centrifugal control mechanism mounted on the fan, a lever biased by itsweight to swing toward the rotor, a mou'ntingon the casting for nivotall'y aupilortina' the leverJaid am mechanism, when, the rotor is below predetermined speed, contactinx the lever to hold it away from the rotor, and when the rotor is above such speed freely retracting from'the lever, a relief eway extending from the cylinder to the inletaideoi the compressor, a needle valve rod in said passageway and adapted to aeat therein to close the same, and a connection between the lever and the rod to inove aaid rod to closing position when the centrifugal means is retracted.

7. In a hermetic compressor of the type having an interconnected motor and compressor wholly enclosed in a sealed casina, a casing memher formed with a vapor inlet communicating with the upper Dart thereof. a casting member formed with a flange, a motor stator mounted in the flange and a motor rotor mounted within the stator. a compressor working chamber formed on the chamber for compressive action, a discharge paaaaaeway communicating with the working chamber, a conduit connecting the discharge passageway directly to the exterior of the'caslng throuahthe wall thereof, a fan mounted on the rotor adjacent the upper portion of the casing to; circulate entering vapor therein from the motor to the casing wall, thereby to transfer motor heat,

means on the casting ior resiliently mounting the motor and compressor on the bottom of the easin: member, aaid casting and easing member bein: otherwise, spaced from each other.

-, JENB 'rounom.

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