US1584243A - Control for refrigerating machines - Google Patents

Description

May 11 1926. 1,584,243

K. D. PERKINS ET AL CONTROL FOR REFRIGERATING MACHINES )(Q @BTM INVENTORS ICMA,

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ATTORNEY May l1 1926. 1,584,243

l K. D. PERKINS ET AL CONTROL FOR REFRIGERATING MACHINES Filed Oct. 11, 1923 4 Sheets-Sheet 2 May 11 1926.

AK. ,l:1 PERKINS ET AL CONTROL FOR RFRIGERATING MACHINES Filed Oct. 11, 1923 4 Sheets-Sheet 3 K MQQB, @WMM INVENToRs l ATTORNEYS May 11j, 192s. 1,584,243 K. D. PERKINS El' AL CONTROL FOR HEFRIGERATING MACHINES ulllllll.

INVENTOR S @Eff v @wm 'fw ATTORNEYS the invention has for its object the provi- KABL'D. PERKINS, OF YOBK, N.

PATENT OFFICE.

CONTROL FOR BEFRIGEBATING MACHINES.

Application led October 11, 1923.- Serial No. 667,800. I

The present invention relates to a system of thermostatic control for refrigerating machines, particularly for refrigerating machines'ior the so-called 'electric re.- frigerators intended for domestic use, and

sion of an improved refrigerator control system and apparatus.-V v v Domestic refrigerators in which the refrigeration is Vproduced mechanically, as used in private residences, restaurants, hotels, etc., are usually provided with a low temperature compartment and a relatively Warm'storage compartment. The lowtemperature compartment is utilized whenever it is desired to obtain a relatively low temperature such as in maln'mg ice, the temperature of this compartment being ordinarily from 20 to'30 F. lThe relatively warm compartment is usually considerably larger than the low temperaturev compartment and is utilized for the storage of perishable articles'of food, the temperature of this compartment usually being maintained between 40 and-55 F.

A mechanical refrigerating device or apparatus is provided for extracting ythe heat from the ice making compartment and the storage compartment. Such a device is ordinarily driven by jan electric. motor and for the sake of economy this motor is arranged to be operated intermittently. It is 'therefore necessary to provide an automatically acting control to start and stop the motor at the proper times.

It is important that the ice making compartment be kept below freezingtemperature as long as there is any water remaining unfrozen in .thefreezing flasks placed in this compartment. When the demand for ice is relatively large the low temperature ice making compartment may be kept below freezing temperature, say from 20 to 30 F., for a relatively long period of time, and it is important in such a case,` as well as at all times, that the temperature of the storage compartment be not allowed to get too low, say, for example, below 35 to 40"4 F., as this would damage or freeze the food stored Within the compartment.

When the water in the freezing flasks has all been frozen, however,. it is no longer necessary. to operate the refrigerating device for the purpose of freezing ice, and the apparatus may be shut down. The temper- Y., Ann ALFRED n. ma, or NEWARK, NEW JERSEY. 1 I

ature .of the whole refrigerator4 will now i begin to rise and the storage compartment, being larger than the low temperature compartment, may warm up v faster than the low temperature compartment. l Under these conditions, shouldl the temperature of the storage compartment rise above the maximum desirable temperature therein, the.

driving motor must again be started soas to cause' a circulation of I, cooling Huid through the storage compartment. It is also of importance tolmowwith accuracy the value of the temperature in the storage l and the ice making compartments. v

According to our present invention, We

provide a refrigerating device operable to reducethe temperature in the low temperature compartment of the refrigerator, and:

we provide a relatively warm compartment normally in communication with the low temperature compartment, and means operable by temperature changes in the low temperature compartment' for controlling the refrigeratmg device, means being also 4provided, which are operable by tempera.-

ture changes in the relatively warm compartment, for controlling the communication with the low, temperature compartment. This last named means maypalso, if desired, be made operable at a ypredetermined temperature in the low temperature' compartment to control therefrigerating d evice in' accordance with the temperature changes in the warm compartment as long 1 as the predetermined temperature in the low temperature compartment exists. We also provide means for indicating the temperatures in either or both ofthe above mentioned compartments with a relatively high degree of accuracy.' Ourinvention further contemplates an improved'form of means for controlling the driving motor of the refrigerating device and for indicating -in a unitary housing structure which is particularlysuitable for installation in a refrigerator of the domestic type. p

In order that these as well as other novell features of the invention may be more fully understood, reference is made to the accompanying 4drawings illustratin by Way of example, a mechanical emb ent of the inventive idea. These drawin however, are intended to assist the descrlption of the invention and not to define the limits thereof. In these drawings: y

Fig. l is a view in vertical cross sectlon of a refrigerator provided with our lmproved control system and apparatus;

Fig. 2 is a viewA partially in longitudinal y section and partially in elevation of' a combined temperature indicator and thermostatically operated switch for controlhng the driving motor;

Fig. 3 is a front view of the device lllustrated in Fig. 2 showing the' temperature 1ndicator; v

Fig. 4 is a view in transverse section taken on line 4-4 of Fig. 2 showing a mercury tube switch in closed position;

Fig. 5 is a view similar to Fig. 4 showing the switch in open position;

Fig. 6 is a schematic diagram showing the electrical connections of the driving motor; Fig. 7 is is a view in longitudinal section of a combined temperaturel indicating device and thermostatically operated damper fon controlling the communication between the low temperature compartment and the relatively warm compartment; n

Fig. 8 is a front view of the device illustrated in Fig. 7 showing the temperature indicator;

F1g. 9 is a v1ew 1n transverse sectlon taken on line 9-9 of Fig. 7 to show the flexible shaft connection;

Flg. 10 1s a view 1n transverse section I taken on line 10-10,of Fig. 7 to show the 'rangement of .ment 21 and the relative ment 22 are constructed preferably of suitrelative arrangement of the operating parts 3f the damper, and its position inthe air uct';

Fig. 11F is a view partially in elevation and partially in longitudinal section of a combined temperature indicator, 4thermostatically o erated switch, and thermostatically operate damper employed in a modified arthe thermostatic vcontrol system;

Fig. 12 is a view in longitudinal section taken on line 12-12 of Fig. 11 showing the relative angular position of the mercury tube switch and the damper; and

Fig. 13 is a schematic diagram showing the electrical connections for the refrigerator driving motor in the modified control system.

Referring -to Fig. 1 of the accompanying drawings, there is here shown a refriger ator 20 having a low temperature compartment 21, a relatively warm, or storage, compartment 22, and a third compartment 23. The walls of the low temlperature comparty'warm compartallow the evaporator bell 28 to rotate there- -29 and 30 is such that the aii` is discharged spectively in planes transverse to the axis of able wood filled with heatlinsulatng mate rial 24, .the dividing wall 25 between com partments 21 and 23 beingalso constructe in this manner. The storage compartmen 22 is preferably lined with a sanitary ma terial such as porcelain, which also possesse a relatively large thermal capacity. Suit able shelves 26 4are provided in this com partment on which to place the articles t be cooled.

In the refrigerator shown in the accom panying drawings the low temperature, o ice making, compartment 21 and the storag compartment 22 are refrigerated by mean of a refrigerating machine or device of th Audiffren type, in which the apparatus com prises a pair of rotary communicating ves sels 27 and 28, sometimes called a dumbbell from .their resemblance thereto. In one of the vessels or bells 27, which i's usually Iknown as the vcompressor bell, ltherefrigerating fluid is compressed and condensed,and in the other bell 28, which is known Aas the expansion bell, the Huid is eX- panded to absorb heat from the medium surrounding it. The refrigerating machine is in this instance constructed in accordance with the disclosure in our co-pending- `application S. N. 623,333 filed, March 7, 1923,v the condenser bell 27 being provided with a plurality of heat conducting vanes 29 on its surface, and the surface of the expansion or evaporator bell 28 being also provided with similar heat conducting vanes 30. The refrigerating machine is driven by means of an electric motor 31 through a belt 32 and pulleys 33 and 34, on respectively the motor shaft and the refrigerating lmachine shaft.

In theexample shown the low temperaturel compartment 21 is suiiiciently large to in, and to accommodate the freezing {iasks 35 in which water may be placed and frozen for making ice. When the refrigerating machine is rotated by means of motor 31 heat is absorbed from the medium in compartment 21, which in this case is air, and when the expanded refrigerating iiuid within the evaporator bell 28 is drawn over into bell 27 and compressed by the compressors therein, this lheat is conducted from the surface of bell 27 lby means ofthe radiating fins 29 and discharged to the lsurrounding medium in compartment 23, which in this case is also air. Compartment 23 is provided with suitable openings (not shown) to the atmosphere so .as to provide for ample circulation of the air' into and out of the. compartment. L

The Shape and positioning of the lvanes.

from the surface ofthe bells 27 and 28 rerotation, and air is drawn toward the surface of the bells 27and 28 at all other points.

In this way a particularly effective and rapid 'transfer of heat is obtained .to and from these bells. r

The rotation of vanes 30. on bell 28 causes acirculation of'a-ir to take place through the air duct 36 underneath hood 37 and to the left-hand sideof the relatively warm storage compartment. 22 which is separated from the right-hand side by a partition 38. An aperture 39 is provided, however, at the upper end of this partition through which the air travels to the right-hand side of compartment 22 and returnsto the low tempera-ture compartment 21 by means of air duct 40. By thus placing compartments 21 and 22 in communication with each other the compartment 22 is effectively cooled. v

In order to freeze the water in the iasks 35 it is necessary to maintain the temperature of the compartment 21 below about 30 F., and vit is desirable to maintain it at an average temperature of about 25 F. in order to provide a thermic head which will result in a relatively rapid rate of freezing. It is thus desirable to start the driving motor 31 when the temperature of compartment 21 rises to'about 30 F. and when the temperature of this compartment falls to about 20 F., to stop the operation of the driving motor.

In order to properly store articles of food they shouldbe maintained at a temperature not much lower than 40o F. and not much higher than 55 F., and they should prefer'- ably be maintained at'or near the lower temperature limit. The temperature may not, however, be lowered much below 40 F. without impairing the flavor or otherwise injuring many articles of food. Hence, it will be seen that the storage compartment 22 should be maintained at a temperature somewhat higher than that of compartment 21 and for this reason compartment 22 is rcferred to as the relatively warm compartment.

vIn orderto control the operation of the refrigerating machine so as to control the temperatures of compartments 21 and 22 as above described, we have provided the apparatus illustrated in Figs. 2 to 10, inclusive, of the accompanying drawings. We irst'of all provide a switch 41 (Figs.A 2, 6 and 13) for making and breaking the circuit from the power supply lines 42 to the terminals 43 of'driving motor 31. Switch 41 is preferably lof the mercury tube type and comprises an envelop 44 of glass, quartz, or the like, having in its walls a pair of projections 45 and 46 into the tips of which there are sealed the electrodes 47 and 48 which are provided with suitable terminalsto which one of the supply conductors 42 and one of the motor leads 43 ai'e respectively connected, as shown in the diagram of Fig. 6. The interior of the envelop 44 is exhausted and a small amount of mercury is placed. therein, so that when the tube is at or near ythe horizontal position as shown in Fig. 4, the mercury serves to connect electrodes 47 and 48 and complete the circuit through the tube. When, however, tube 44 is tilted to a position similar to that shown in Fig. 5, the mercury will flow to one end 50 each in contact with its, corresponding electrode, but the circuit throughl the tube having been broken. It should be noted that of the tube leaving the isolated pools 49 and in this form of mercury tube switchthe cir# cuit is broken between two pools of mercury so that the arc formed by the rupture merely vaporizes a small amount of mercury and in no way consumes either of the electrodes The mercury tube switch 41k is appropriately mounted lupon a shaft 51 as by means of the'stirrup 52 and clamping member 53 sothat the tube is gently but firmly supported with its axis transverse to lthat of shaft 51, so that by rotating the latter the switch may be opened and closed.

Shaft 51 is preferably mounted for rotation by means of a sleeve bearing 54 in a sta.- tionary disc 55 and a pivot bearing 56 in a similar stationary disc 57, these `stationary discs being spaced a suitable distance from one another as shown in Fig. 2 and heldv in this position by the distance rods 58, which also serve to clamp the discs 55 and 57 in position. This switch supporting structure is now placed within a supporting housing 59 which it is desirable to make in the form of a tubular structure of sufficient diameter to allow the switch tube 44 to rotate freely within it.

`In the opposite end of the housing 59 we position a temperature-responsive device or thermostat 60, now only briefly referred to, but presently to be described in detail. It is suiicient to say here that this thermostat is provided with a temperature-sensitive bulb 61 which is connected to the thermostat proper by means of a `flexible tubing 62 so' that the bulb v61 may be positioned at any point where it is desired to measure the temperature. A change in the temperature of bulb-.61 effects a rotation of shaft 63 of the thermostat, which projects forwardly ofthe instrumentl to carry an indicating pointer 64 (Fig. 3) adapted to move over a scale 65, and which projects rearwardly of the ther mostat to actuate shaft 51 through the ilexiblc coupling 66. This coupling comprises a transversely extending pin G7 (Figs. 2 and 9) mounted in the hub (i8 on the thermostat shaft (i3, and a longitudinally bent forked member 69 carried by hub 70 on the switch shaft 5l. liy using this flexible coupling it is unnecessary to place shafts 5l and 63 c:;- actly in alignment with one another. lThe length of the arms of the forked member 59 is such as to allow of a small amount of end play between' shafts 51 and '63.' The spacin' between each pair of arms of the forke member 69 is somewhat greater than the diameter of the pin 67, and by varying this spacing sopas toprovide a'certain amount of lost motion Vin the operation of shaft 51 by shaft 63, the time of the opening and closing of switch 41 may be' adjusted.

The thermostatically operated switch just described is mounted preferably in the front of the refrigerator by providing a recess 71 therein at a suitable position and inserting the tubular housing 59 which carries the mercury tube switch andthe thermostat in a single unitary structure which may be easily removed for inspection or repair by merely taking out the screws 7 2.

The temperature-sensitive bulb 61 is posi.- tioned in the low. temperature compartment 21 in proximity to the freezing flasks 35 so that -the rotation of the shaft 63 is dependent upon the changes of temperature at this point. By appropriately setting the angular position of the mercury tube 44, switch 41 may be made to open when the indicator 64 is at 20 F., and by appropriately designing tube 44, or by' varying the spacing between -the pairs of arms on the forked member 69 of the flexible coupling, the switch- 41 may be made to close at 30 F. With these adjustments -made, the thermostatically operated switch 41 is operable by temperature changes in the low temperature compartment 21 to control the operation of the refrigerating machine, this switch closing l when the temperature in compartment 21 reaches 30 F. so as to place the refrigerating machine in operation. This operation will continue until the water in the freezing flasks 35 is frozen, after which the temperature in the compartment will drop to around 20 F. at which point switch 41.will open and stop the operation of the refrigerating machine. l

In order to properly control the temperature in the relatively warm storage compartment 22 so that it will not fall too low and damage the articles stored therein, we provide the thermostatically operated valve, or damper, illustrated in Figs. 7 to 10, inclusive. This device is housed in a tubular member 73 in a similar manner to the switch 41. Member 73, however, is of metal, and inasmuch as the inner end of this member is subjected to a relatively low temperature while the outer end is at room temperature, a considerable amount of heat will tend to flow toward the cooler portion. In order to intercept this flow of heat the forward end of tubular member 73 is insulated from the is carried in sleeve bearings 76 and, 77 and 'a pivot bearing 78. These bearings are mounted 1n discs 79, 80, fand 81', respectively, disc 79 being disposed `toward the outer'end ,of the` tubular housing` 73, and discslSO and lserving to co-actwith the ends of vane 74 'togclose the l'air, passage. These discs are secured together and held 'firmly in spaced relation by means ofthe bolts 82. The housmg 73 is insertedin an aperture 83 (Figs.1 and 10) which is let in from the face of the refrigerator for a suflicient depth to reach the air duct 40 and so as to hold the damper 74 in position opposite the openings formed bythe intersection of recess 83 with the air duct. Appropriate openings 84 are provided 1n each side of the housing 73 so as to allow for the passage of air transversely of the housing and past the vane 74. A pair of flanges 85 is provided which extend inwardly from the inner surface of housing 73 to co-act with the longitudinal edges 86 of the vane 74 to close the passageway through the air duct, and the inner edges of these flanges are extended circumferentiallyas shown at '87 in order to allow a certain amount of freedom of movement of vane 74 withou again opening the passageway.

This damper, or vane, 74 is actuated by the rotation of shaft 75, iexible coupling 88 (slmilar to the one previously described) and shaft 89 of a second temperature-responsive device, or thermostat, 90, which is also similar to thermostat 60. The details of the ponstruction of these thermostats are as folows.

Within the casing 91 there is mounted on a boss 92 firmly attached to the inner end of v casing 91, a relatively long hollow Bourdon coll 93. The opposite end 94 of this` coil is dlrectly attached to an arm'on shaft 89. A

temperature-sensitive bulb 95 is connected* 110 by means of a flexible capillary tube 96 with the inner end of the Bourdon coil 93, andthe bulb, capillary tube, and coil are completely filled with a suitable thermometric fluid. When the temperature to which the bulb 95 is subjected is increased, the thermometric substance expands and the increase in pressure caused thereby causes the outer end 94 of the Bourdon coil to move by a corresponding amount. Because ofthe extraordinary lengt-h of the Bourdon coil the shaft 89 and the indicating pointer 97 mounted thereon are rotated throughout the full scale of the instrument.

The temperature-sensitive bulb 95- maybe placed at any point in the relatively warm storage compartment desired, but it is preferably located, as shown in Figs. 7 and 1,`

withinv the housing 73 on the storage compartment side of the damper 74. With the thermostatic damper just described operating in conjunction with the thermostatlcally 21 being below 30 F. After the refrigerating machine has been operated in this manner for a certain period of time the temperature in the storage compartment 22 will be lowered and the damper 74 will move towardsthe closed position. The damper is preferably set to close at 40 F. so that when this ,temperature is reached the circulation' ofthe cold air between compartments 21 and 22 through the ducts '36 and 40 will be cut off. Compartment 22 will now begin to warm up and then damper 74 will slightly open, a condition of equilibrium being finally reached- When the water in the freezing flasks 35 becomes completely frozen and the temperature Vof compartment-21 reaches 20 F., the switch 41 shuts downthe refrigerating apparatus and both compartments 21 and 22 begin to increase in temperature. The temperature in compartment 22 may become greater than 55 F. before the temperature y1n compartment 21 reaches 30 F. and the refrigerating apparatus is started again. In Vp order to prevent the temperature in the storage compartment 22 from rising above a predetermined amount, say or 55 F., under these conditions, we have provided the modivp fied refrigerator control which is illustrated Figs. 11 to 13 of the accompanying drawin s.

eferring t-o these figures, a second mercury tube switch 98 is mounted on shaft 75 of the thermostatic damper 74, there being ordinarily"'suflicient space between discs 79 and 80 to adequatelyV accommodate this switch. In this manner the thermostat 90 is arranged to control simultaneously damper 74 and switch 98. `Theterminals of switch 98 are connected in parallel with the terminals of switch 41, as shown in-Fig. 13, so that motor 31 may be started by the closing of either switch 41`or 98, but the motor will not stop unless bothof these switches are thrown to open position. v

- In order to make the thermostat, switch 98, and damper self-contained, that is, to `1 provide for the removal of these' elements from the refrigerator by the simple withdrawing of their tubular housing from its recess, sliding electrical contacts may-be employed to make the connections from the conductors leading from the terminals of switch 98. For this purpose the conductors 99 and 100 -lead from the terminals of switch 98 to a pair of contact segments 101 and 102 which are mounted in insulating inserts 103 Y and 104 mounted in the surface of the housing. Flexible contacts 105 and 106 are suitably mounted in the walls of the recess for the housing so as to make contact with segments 101 and 102,-respe'ctve1y, when the lunit is slid into its recess. : f Conductors 107 and 108 are respectively'connected from the @terminals of switch 41 to'ispringl contacts 105` yfrom two-thirds to full open, theswitch may be made to close at from 50 to 55 F. and the damper will be suiciently open to allow adequate circulation to take place. A suitable position of the switch 98 with respect to. damper 74 is shown in Fig. 12, inwhich switch 98 is adapted to close when indicator 97 (Fig. 8) is at 50 F. and'when damper 74 will be about two-thirds open.

Let us assume that al refrigerator is equipped with the modification ofthe automatic controlv just described, and that the temperature of compartment 21 is down to 20 F. so that the refrigerating machine is not running. Under ,thesel conditions the and 22 will begin to rise and damper 74 will open, but is powerless to control the temperature of the compartment because no aiir is being-circulated. If the temperature of comartment 22 now rises to 50 switch 98 will close, placing the refrigerating apparatus again in operation and causing circulation of 'cold alrthrough the storage comartment.` The lower temperature thus produced will act on the temperature-sensitive bulb 95 to turn switch 98 toward open position, but by suitably designing `the contour of the switch envelop or by adjusting the spacing between the pin and forked arm of the flexible coupling 88, switch 98 may be made to remain closed'unti'l the temperaturein compartment 22 has fallen to an appreciable extent, say, for example, to 45 F.

The control of the driving motor'31 is thus placed under switch 98 and bulb 95 which will maintain the temperature of the storage compartment between 45 and 50 F., until the temperature of compartment 21 again rises to 30 F. In other words, switch 98 is operable upon a predetermined reduction in .temperature of both the compartments 21 temperaturein compartment 21 to control the operation of the refrigerating machine.v

The employment of the-,improved control system of our invention ensures that the refrigerating machine shall be placedin operation whenever either the low temperature or ice making compartment requires add.- tional refrigeration, or when the relatively warm or storage compartment requires refrigeration, and the demands of the two compartments are so coordinated that neither too high a temperature nor too low a temperature may exist in the storage compartment, and at the same time so that the refrigerating apparatus will not be kept running when it is not necessary. In this way the cost of operation of the refrigerator is reduced toa minimum. By employing a temperature-responsive device of the Bourdon tube type for the actuation of the driving motor controlling switch, providing this device with a pointer and scale, the operation of the switch at the desired predetermined temperatures is assured and an accurate indication of the temperature existing in the compartment is obtained, The direct connection of the thermostatic element with the operating shaft eliminates the necessity of gears or other .multiplying mechanism. These'same advantages are obtained in the operat-ion of the automatic damper. Furthermore, by employing a mercury tube switch which is actuated by a temperaturesensitive device of'the Bourdon tube type, the motor circuit may be controlled directly by the switch without the necessity of using relays for carrying the loadcurrent. This is a distinct advantage, inasmuch as such relays are apt to get out of order and increase the maintenance expense of a refrigerator. By providing the tubular housing all of these elements are properly protected from injury and at the same time so mounted that it is an extremely easy matter to remove them for inspection or repair.

We claim:

1. In a refrigerator having a refrigerating chamber, a refrigerating device operable to produce temperature changes therein, and a storage compartment normally in communication with said refrigerating chamber, the combination of, means operable by temperature changes in said chamber said refrigerating device, and means operable by temperature changes in thestorage compartment for controlling-the communication with the refrigeratingrchamber and for controlling said refrigerating device.

2. In a refrigerator' having a refrigerating chamber and a storage compartment with a for controlling' cooling fluid circulating therebetween, and having a refrigerating device operable to cool the refrigerating chamber, the combination of means operable byv temperature changes in the refrigerating chamber for controlling said refrigerating device, and means operable by temperature changes in the storage compartment for controlling the circulation of the cooling fluid and for controlling said refrigerating device.

3; In a refrigerator having a refrigerating chamber, a storage compartment, air ducts for placing said compartments incommunication with one another, a refrigerating device operable to produce temperature changes in said refrigerating chamber, and an electric driving motor for said refrigerating device, the combination of a thermo# statically operated switch in the circuit of said driving motor operated by temperature changes in said refrigerating chamber, and a thermostat operable by temperature changes in the storage compartment operatively` connected to act-uate a second switch in the circuit of said driving motor and a damperl in one of said air ducts.

' 4. In a refrigerator, a refrigerating chamber and a storage compartment in communication with one another, a refrigeratinkr device operable to cool the refrigeratiug c amber and to circulate cooling fluid bet-Ween said chamber and the storage compartment thereby to cool the latter, and means operable by temperature changes in the storage .compartment for cont-rolling the lipow of 4cooling Huid between said compartment and chamber and for controlling said refrigerating device.

In testimony tures.

whereof we aiix our signavALFRED D. KARR.

K. D. PERKINS.

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