US2234742A - Refrigerating apparatus - Google Patents

Description

March 11, 1941. 5 1 2,234,742

REFRIGERATING APPARATUS Filed April 28, 1937 5 Sheets-Sheet 1 fig).

1 VENT OR BY g I I 6% ATTORNEYS March 11, 1941. s n- 2,234,742

REFRIGERATING APPARATUS Filed April 28, 1937 5 Sheets-Shee t 2 INVENTOE. BY

' ATTORNEYS March 11, 1941. I H s n- 2,234,742

REFRIGERATING APPARATUS Filed April 28, 1937 5 Sheets-Sheet 5 IN VENTOR.

BY. M

March 11h; 1941, awn-1L 2,234,742

REFRIGERMIING APPARATUS Filed April 28. 195W 5 Sheets-Sheet s ATTORNEYS Patented Mar. 11, 1941 Harry F. Smith, Dayton, Ohio, assignor to General Motors Corporation, Dayton, Dhio, a corporation of Delaware Application April 28, 1937,

(Cl. 230-34) I 1 8 Claims. This invention relates to refrigerating appara tus and more particularly to an improved c'onstruction of refrigerating systems and motor- I compressor units.

g In early refrigerating systems compressors were driven by an external driving means usually through a shaft seal upon the drive shaft of the compressor. Such compressors are still I being used; but the shaft seals, while'they have been ill considerably improved, have always been, and

are still, a. source of considerable trouble. In the smaller sizes of household units, sealed units containing the motor and compressor have been employedto eliminate the shaft seal. However, in

it such sealed units, it is necessary to use alternatulug current motors because direct current motors cannot be used in the presence ofxthe common refrigerants. i

It is an object of myiinvention to provide improved form of refrigerating system wherein:

no shaft seal is required.

In systems employing conventional motor compressor units, the compressor motor is subject to stalling upon heavy refrigeration loads. It is another object of my invention to provide a refrigerating system wherein a condenser, evaporator, and compressor are used and in which a compressor, movable independently of the remainder or the system, is provided with an inertia-operated piston which is operated by an'external motor which moves the compressor housing in such a way that thepiston or the impeller oi the piston is driven by inertia without any direct connection with the motor. I

It is another object of my invention to provide a free and improved form of inertiavoperated compressor wherein means are provided to gradually stop the movement of the piston at each end of the stroke. v It is a further object oi my invention to pro vlde an improved, more efficient form of inertiaoperated compressor wherein the inertia of the body of the compressor is absorbed by springs and returned as useful energy. a

It is still another object of my invention to provide improved connecting means between the iIl-.-'

ertia-operated compressor and the remaining elements'oi the refrigerating system. I

It is another object of my invention to improve the emciency and mechanical advantage of en -inertia-operated Iree piston compressor.

Further objects and advantages of the present invention will be apparent irom the following description, reference being had to the accom- SerlalNc. 139,551

panying drawings, wherein a preferred iorm of thepresent invention is clearly shown.

In the drawings: 1 Fig. 1 is a view in elevation of a motor-compressor-condenser unit embodying my invention; Fig. 2 is an enlarged section of a cylinder head similar to that shown in Fig. 5; I

Fig. 3 is a sectional view taken along the lines 3-3 of Fig. 2;

, Fig. 4 is a view of a domestic refrigerator cabinet embodying the motor-compressor-condenser unit shown in Fig.1;

Fig. 5 is an enlarged view of the compressor, partly in section, shown in a position like that of Fig. 1;

Fig.6 is a view in elevation of the compresso taken from the right side of Fig.5 showing the upper portion of the compressor in section;

Fig. 7 is a sectional view of the motor and countel-weight taken along the line 'i I---| of Fig. 1; Fig. 8 is'a sectional view similar to the upper portion of Fig. 5 of a modified form of compress01 I J. x

Fig. 9 is asectional view taken along theline 99foi Fig. lO shOwing' another. modified form of the inventiongand,

Fig.10 is a sectional view taken along the line.

nc-wof Fig. 9.

frigerator cabinet provided with a refrigeration systemhaving a stationary motor, condenser, and evaporator but having a compressor, rock'- ably mounted, connected to the remaining portions of the refrigerating system by flexible connections. This rockably mounted connection has opposed pistons therein which are sufiiciently I heavy to be operated by their own inertia created by the oscillations of the compressor. The compressor is oscillated through a. connecting rod which is connected to an external portion of the 40 housing of the compressor at one end, but at the other end, to-a counter-balanced crank pin upon the motor shaft. I I

Referring now to the drawings and more particularly to Figs. 4. and i, there is shown a 4 domestic electric refrigerator cabinet 20 having a food compartmentit containing a refrigerant evaporator N which cools the food compartment 22 and also is provide ziwith shelves for receiving ice trays to ireeze'ice' Below thefood com-1 partment 22 is a-machine compartment 26 which contains the motor-compressor showniinili'itl.

1. This motor-compressor unit shown inFig. l. is provided with a base 23 which supports either a direct current or alternating current electric motor 36 as well as the condenser 32 and a receiver 34. The compressor withdraws evaporated refrigerant from the evaporator 24 through a return conduit 36 and compresses this gas and forwards the compressed gas to the condenser 32 where it is liquefied and collected in the receiver 34. From the receiver 34 this liquid refrigerantis forwarded to the evaporator through the supply conduit 38.

Referring now, also, to Figs. 5 and 6 for a further description of the compressor, there is shown a compressor base 46 which is mounted upon the motor-compressor bas 28. This compressor base 40 is provided with a slotted boss 42 which receives the lower end of a rubber web member 44 retained in the slot by a screw 46. The upper end of this rubber member 44 is re-= ceived within the slotted boss 46 and retained by a screw 60. This slotted boss 46 is at the bottomof a rather large casting 62 which, at its lower portion, has the wings 54 and 56 which rest upon coil springs 58 and 66, These coil springs I Eli-and 66 preferably have a natural frequency of vibration when the inertia of the large casting is considered which is the same as the frequency at which the compressor is to be oscillated.

Above the boss- 48 is the compressor inlet 62, and above this inlet is a crank case 64 which forms a sort of a lubricant reservoir. Upon opposite sides of the upper portion of this lubricant reservoir are the cylinders 66 and 68. Opposed pistons 18 and 12 extend into the cylinders and are connected together within the crank case by top and bottom plates 14 and 16 which leaves a. space between the inner ends of the pistons to form a Scotch yoke. Pins 18 and 88 extend into this Scotch yoke and are cast integral with the flywheels 82 and 84 which are provided with bosses 86 and 88 which receive the pins and 32 which protrude from the walls of the crank case 64. These pins are held in place and the crank case sealed by the plugs 88 and I02 which hold the pins in proper position. The top of the crank case is closed by a lid I64.

The pistons are provided with identical inlet valves I06 and I68 in their heads. The inlet valve I66 is connected with the crank case through a passage H6, while the inlet valve I68 is connected with the crank case by apassage II 2, The cylinder 66 is provided with a removable cylinder head IHl provided with a discharge valve H6, while the cylinder 68 is provided with a removable cylinder head H8. The removable cylinder head H8 is provided with a discharge valve I20. The discharge valve 6 is kept in position by a pin I22 which is surrounded by a valve spring I24 extending between the cylinder head I I4 and the valve vI I6.

The inlet opening 62 of the compressor is con nected by a flare nut I26 with a coil portion I28 of the return conduit 36 which is coiled about the axis of the flare nut to provide sufficient flexibility to accommodate the rocking movement of the compressor. The cylinder heads II 4 and H8 are connected to discharge coils i3!) and I32 which provide a flexible connection with the conduit I34 which conduits the compressed refrig erant to the condenser 32. The surface of these coil tubes I30 and I32 also serves as a condensing surface.

The compressor is provided with a slotted boss I36 which receives laminated strip I38 retained at the boss I36 by a screw I46. The other end of the laminated strip I36 is retained within the slot in the end of the connecting rod I42 by is screw I44. The other end of the connecting rod I42 is provided with a bearing I46 which is mounted upon a split crank pin upon the motor shaft. Upon the end of the motor shaft a counterweight M8 is fastened by a set screw I56. The upper portion of this counterweight .is provided with an extension I62 which forms one half of the crank pin bearing surface. The other half of the crank pin bearing surface is formed by a plug I54 with a shoulder which is fastened to the counterweight member by a cap screw I56. The counterweight M8 substantially balances the weight of the crank pin and the adjacent portions of the connecting rod I42. The laminated connection I38 provides a connection which requires no lubrication or maintenance,

When the motor operates it reciprocates the end of the connecting rod adjacent the compressor causing the compressor to oscillate about an axis which is near the boss 48. The casting 52 is made as light as possible and may be made of magnalium or aluminum. If desired, the cylinders may be provided with sleeves or inner liners of a harder material.

The springs 68 and 66, when the inertia of the compressor is taken into account, have a natural frequency of vibration which is identical to the frequency of the oscillations imparted to the compressor by the electric motor and connecting rod I42. The upper portion of the compressor rock back and forth upon the springs 58 and 66, and v the springs 68 and 66 take up the inertia of the compressor body. The rocking action of the compressor causes .amovement between the pistons and their cylinders to provide suction and compression strokes of the pistons within the cylinders. This is due to the fact that the piston tends to stay stationary while the cylinder body moves.

The inertia of the compressor body at the two ends of its stroke is taken up by the springs which start it back in the opposite direction. The energy in the form of the inertia of the compressor body is transmitted to the springs which return it to the compressor body so that the energy incorporated in the inertia of the compressor body is not dissipated.

The Scotch yoke and crank connection between the pistons and the flywheels limits the movement of the pistons at eachend of the stroke so that the discharge valves will not be damaged by excess movement of the piston. The flywheel and the crank pin limit and control the movement of the pistons and thus make the action of the pistons and the compression of the refrigerant more uniform. In order to prevent the pistons from stopping upon the dead center of the crank pin when the motor-compressor unit stops, I provide a tension spring 15 extending between the connecting plate 14 and the lid I64 to apply a slight pull, which would tend to keep the pistons in center position when the compressor is idle.

In Fig. 8, an improved modification of the cornpressor is shown. In this improved modification, the remainder of the compressor, the motor and the refrigerating system is the same as that shown in Figs. 1 to 7 inclusive. However, the crank construction is improved over that shown in Figs. 1 to 7. In this figure, the compressor is designated by the reference character I52, and has a casting I64 which forms the crank case wall and the cylinders I66 and I68. Within the cylinders are the pistons I16 and I12 connected by the plates I14 and I16 to form a Scotch yoke. Within the Scotch yoke u a slidable block I18 which iii receives the crank. pin ltd connected to the flywheel iii. Within the Scotch yoke, a compression type coil spring I84 urges the block iii towards the upper end of the yoke, so as to tend to keep the pistons in the dead center position when the compressor is idle.

a passage its is provided, which connects to the inlet valve tilt formed in the piston lid, while the passage itll is provided in the piston lit which connects to the inlet valve iii provided in the head of the piston iii. The cyl inder ltd is provided with a cylinder head ltd provided with a discharge valve itli, while the cylinder ltd isprovided with a cylinder head Hid, provided with a discharge valve iii. The top of the crank case is covered by a plate 2%.

In operation, when the motor begins to rock the compressor, the pistons remain substantially stationary. However, when the motor ap= till proaches its full speed, the pistons begin to move back and forth under the control of the crank pin iii! and the block ilt within the Scotch yoke along with the spring iii, which gradually permits the pistons to assume a full compression stroke at each end. The crank pin and Scotch yoke, however, prevent the pistons from traveling far enough to damage the discharge valves. The flywheel idi may oscillate or may make complete revolutions when the compressor is operating at full speed. In either type of operation, the cornpressor operates at maximum efficiency as it comes up to approximately full speed.

The weight of the pistons plus the Weight of the Scotch yoke is suficient to draw in the gas from the crank case through the passages lid and lid through the piston valve into the compression chamber and to compress the gas within the com pression chamber and force it out oi the compression chamber through one of the discharge valves Hit or tilt. Since the compressor does little compression except when the motor gets up to speed, the compressor is virtually unloaded at its start. It the compression load is too heavy, the motor will not be overloaded because of the character oi the compressor load and the pistons will not reach top dead center.

in Figs. 9 and it), another improved modification is shown. in this modification, the compressor is suspended from a bass 2% which is fastened to form an overhead support provided upon a motor-compressor platform similar to the platform 2% shown in Fig. l. provided with a boss 208 having a slot which receives a rubber member 2) held in place by the screw iii. This rubber member serves as a sort of a pivot for the compressor. The lower end of the rubber member 2|fl is received within a slot in the boss 2 I t of the compressor casting MS. The compressor casting 2H5 has wings 2m and tilt, which support the compression coil springs iii and 2% which extend between the wings 2 it and lid and the base 206.

The compressor casting HE is provided with an inlet opening 226 which provides communication through the hollow neck 228 with the crank case portion 230 of the casting 2l6. This hollow neck 2% is provided with a split boss 232, which receives one end of the laminated metal flexible connecting member 234, which has its other end received within a slot in one end of the connecting rod 236. One end of this flexible member 23% is held by the screw 238, while the other end is held by the screw 240.

The crank case 230 is provided with cylinder walls 2M and 244 on opposite sides. These cyl- This base. d is inders are provided with pistons Nd and are, each oi which is provided with inlet passages and inlet piston valves similarly to that shown in Figs. 2 and d. The cylinder 242 is provided with a cylinder head 250 having a discharge valve (not shown), while the cylinder 244 is provided with a cylinder head 252 having a discharge valve 25 which controls the discharge oi" gas from the compression chamber of the cylinder iii,

The piston tilt is provided with recesses on either side of the connecting bar which connects the pistons 246 and Mt. Received within these recesses are flexible laminated connecting rods. 25% and 260 which are formed of a number of thin leaves of spring steel or spring brass. The ends of these flexible connecting rods 2% and the are held by pins 262 and 2M which pass through holes or longitudinal slots in the leaves. The end of the flexible connecting rod opposite the piston is connected to a hearing member ltd fitted to the crank pin did, while the connecting rod 2% is similarly connected to a bearing and crank shaft upon the opposite side or" the bar tilt. in this manner, the connecting rod its is connected to an eccentric weight kid rotatably mounted within the hearing till, while the connecting rod it'll is connected to the eccentric weight kit which is pivotally mounted in the bearing tit. These connecting rods naturally tend to assume a straight position, but the weights, when the compressor is idle, are sufliciently heavy to force them to a bent position as shown in Fig. 10. With the aid of the gas being compressed. the connecting rods are sumciently powerful under ordinary circumstances to stop the pistons and the weights at the dead center position. The bottom oi the crank case is closed by the plate ltd. The connecting rod tilt is connected to an eccentric upon the electric motor shaft in a similar way as that shown in Figs. 1 and '7.

When the motor begins to operate, it slowly oscillates the compressor head lid. However, when the motor and compressor approach full speed, the weights Elli begin to oscillate with the pistons, thus drawing gas from the crank case and into the compression chamber and then expelling the gas from the compression chamber through the discharge valve to the condenser. It should be noted that the Weights tit and iii are so designed that they may make a complete revolution if so desired. However, normally these plates will oscillate substantially 90 from the position shown in Fig. 10, and it should be noted that toward the end of each stroke when the greatest amount of power is required, these weights have their greatest amount of mechanical advantage in forcing the piston to the end of its stroke. These weights naturally tend to cause the pistons to assume an intermediate position when the compressor is idle. The rock ing parts of the compressor, particularly the cylinder heads and the crank case, may be made of light-weight material such as aluminum or magnalhun.

Preferably, the weight of the compressor is so adjusted to the tension of the springs that the system has a natural vibration frequency, which isequal to that of the rocking of the compressor by the electric motor whem operated at full speed. Likewise, the weights 210 and 2m, togather with the spring of the connecting rods 258 and 260, when the weight of the pistons is taken into account, have a. natural vibration frequency which is equal to the frequency of oscilill iations of the compressor provided by the motor at full speed. In this connection also, the compressor is virtually unloaded when the'motor starts-and does not begin to pump the refrigerant until the motor approaches full speed. lmrthermore, an unusually heavy load uponthe compressor will not overload the motor because the piston will only be moved as far as can be done by the inertia provided by the motor and in this Way, the compressor load is prevented from becoming abnormally high. Also, if the compressor should stick or not operate properly, the motor will not be damaged. This construction makes it possible to use an. external electric motor without employing a shaft seal upon the compressor. The compressor is connected to the refrigerating system in a manner similar to that shown in .Fig. 1 with the diiierence that the connections of the liquid and return conduits are reversed from that shown in Fig. 1.

Thus, by my invention, I have provided a sealed refrigerating system which may be operated by an external electric motor which is particularly useful where a direct current only is available. The evaporator, condenser, and the remaining portions of the refrigerator may be conventional. Thus, I have provided an improved form of refrigerating system which is particularly useful when only direct current is available.

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

What is claimed is as follows:

1. Refrigerating apparatus including a closed circuit incorporating a compressor, a condenser and an evaporator, said compressor incorporating an inertia-operated impeller, said evaporator being normally mounted in a fixed position, said compressor being yieldingly mounted and movable with respect to the remainder of the refrigerating system, and means for reciprocating the compressor independently of the evaporator for operating the impeller by inertia.

2. Refrigerating apparatus including a closed circuit incorporating a compressor, a condenser and an evaporator, said compressor incorporating an inertia-operated impeller, said evaporator being normally mounted in a. fixed position, said compressor being yieldingly mounted and movable with respect to the remainder of the refrigerating system, nd means for moving the oneness compressor independently of the evaporator to operate the impeller by inertia.

3. Refrigerating apparatus including a closed circuit incorporating a compressor, a condenser and an evaporator, said compressor incorporating an inertia-operated impeller, said evaporator being normally mounted in a fixed position, said compressor being yieldingly mounted and movable with respect to the remainder of the refrigerating systeml, and means for moving the compressor independently of the evaporator to operate the impeller by inertia, said compressor being provided with yielding connections with the remainder of the refrigerant circuit.

' i. A compressor including a housing containing a free piston operable by inertia, a crank and weight for controlling the movement of the pis ton, yielding means for yieldingly holding said piston in the mid-portion of its stroke, and means for moving the housing to operate the piston by inertia.

5. A pump including a housing containing a piston, a crank connected to the piston, said crank being provided with an eccentrically mounted weight, and means for oscillating said housing to oscillate said weight by inertia to operate the piston, said pump having spring means to absorb the inertia of the housing and to return this energy as useful energy in aiding the oscillation of the housing.

6. A pump including a housing containing a free piston operated by inertia, said housing being rockably mounted, spring means for opposing the rocking oi the housing, said spring means together with said housing having a natural frequency of oscillation, and means for oscillating said housing at said natural frequency of oscillation in order to operate said piston.

'7- A pump including a housing containing a piston, an oscillatable weighted member pivoted to said housing above its center of mass, means for connecting said piston and said weighted member, and means for reciprocating said housing for oscillating said weighted member and for reciprocating said piston.

8. A pump including a. housing containing a piston, an osclllatable weighted member pivoted to said housing above its center of mass, spring means for connecting said piston and said weighted member, and means for reciprocating said housing for oscillating said weighted member and for reciprocating said piston.

HARRY F. SMITH.

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