US 2178807 A
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Description (OCR text may contain errors)
Nov. 7, 1939. c. E. PLOEGER 2.178.807
REFRIGERATION Filed Dec. 20, 1935 3 Sheets-Sheet 2 049,5 96nd, A ATTORNEY.
Nov. 7, 1 939.
C. E. PLOEGER REFRIGERATION Filed Dec. 20, 1935 3 Sheets-Sheet 3 INVENTOR.
O QAQM 4 ATTORNEY.
Patented Nov. 7, 1939 UNITED STATES PATENT OFFICE REFRIGERATION Clyde E. Ploeger, Evansville, Ind., asslgnor to jServel, Inc., New York, N. Y., a. corporation of Delaware Application December 20, 1935, serial No. 55,309
- controlled responsive to temperature of the air,
and the. refrigeration apparatus being suitably controlled so that operation periods of the refrigeration apparatus are instigated a time interval after instigation of the corresponding operating periods of the fan. With this type of control, operation of the" fan while the refrigeraation unit is idle causes defrosting of the cooling elemen" and as a. consequence there is maintained a higher humidity of the air. I
It is an object of my invention to provide a system of this character in which operation of a refrigeration apparatus is instigated a predetermined time interval after operation of a fan is .instigated, whereby, by alteration of the time interval, there is obtained control of the humidity.
My invention will be more. fully understood upon reference 'to the following description and accompanying drawings forming part of this specification and of which:
Fig. 1 illustrates diagrammatically a forced draft refrigeration system embodying the invention; and
Figs. 2 and 3 are similar to Fig. 1 and illustrate other operative conditions of the system.
Referring to Fig. 1, an enclosure I to be refrigerated is indicated in dotted outline. In the I enclosure Ill is a cooling element comprising an evaporator coil ll of a compression type refrigeration apparatus. The other partsof this apparatusinclude a condenser l2 and a compressor l3driven by an electric motor I4. Re-
, frigerant liquid evaporates in thecooling coil l I,
producing a refrigerating effect. The resulting .vapor flows through conduit ii to the compressor I3 in which the refrigerant vapor is compressed and discharged through a conduit IE to the condenser l2. In the latter, the refrigerant vapor is liquefied and the liquid flows through conduit H to the coil ll, th'us completing the refrigeration cycle. Flow of liquid from the high pressure condenser to the low pressure evaporator coil H is controlled by any suitable device such as a 4' Claims. ((21. 62-4) thermostatically operated expansion valve l8 in the conduit ll.
An electric fan or blower I9 is arranged in the enclosure'lll to cause circulation of air in contact with the evaporator coil II. There is also provided in the enclosure H] a thermostatic switch which is subjected to temperature of the air in the refrigerator enclosure.
The compressor motor l4 and the electr'c fan l9 are connected in a manner hereinaft r de- 10 scribed to a source of electric current supplied by what will be termed line conductors 39'and-42.
It is desired to maintain the air in the refrigerator enclosure ID at a certain temperature,
apparatus and fan until again required. These alternate periods will be referred to as operation periods and idle periods. During operation periods, water vapor is condensedout of the circulating air and deposited on the evaporator coil I l where it may freeze and form frost. The absolute humidity of the air is thereby. reduced. 80 If we operate the fan to blow air over-the coil ll while the condensing unit is idle, the resulting flow of relatively warm air will cause the frost to melt and the water evaporate into the air, thus increasing the humidity of the air. If this is accomplished each cycle of operation, the humidity of the air will not be continually decreased as it would be if the frost were allowed to build W up cycle upon cycle. v To accomplish the above results I provide a 40 control circuit for the condensing unit motor l4 and the electric fan l9 whereby these motors are started and stopped responsive to temperature of air in the enclosure I0 and the electric fan [9 starts 'a predetermined time interval ahead of the 4,5 condensing unit motor It. In addition to the motors l4 and [9, this control circuit includes the previously mentioned thermostatic switch 20, l a transformer 2|, a first solenoid operated switch 22, a second solenoid operated switch 23, and a timing device 24. I will now describe these elements individually.
The thermostatic switch 20 may be of any suitable type which closes upon rise in temperature and opens upon decrease in temperature. This r r the switch 23, a conductor 50,- and the conduc- L J It will now be understood that switch is preferably snap-acting so as to definitely open and close between temperature limits for which it is adjusted. The first solenoid operated switch 22 comprises an operating coil 25 and a pair of normally open contacts 26. The second solenoid operated switch 23 comprises an operating coil 21, two sets of normally open contacts 28 and 29, and a set of normally closed contacts 30. The transformer 2| has a desired voltage ratio for stepping the line voltage, for instance, volts, down to a desired secondary voltage such as, for instance, 24 volts.
The timing device 24 is operated by a suitable electric motor 3| which may be a self-starting synchronous motor. The timing device includes a first switch having an adjustable contact 32 and a rotatable contact 33. The contact 32 may be adjusted by turning a knob 34. There is also a normally closed switch 35 operated by a rotatable arm 36. The rotatable switch contact 33 and the'switch operating arm 36 are arranged to be driven by the timer motor 3| through suitable speed reducing gearing 31.
by means of a conductor 43 to one side 39 of the supply line and the other terminal of the fan motor is connected by means of a conductor 44, the normally open contact 26 of switch 22, and a conductor 45 to the other side 42 of the supply line.
From the above described connections it will be understood that operation of the fan I9 is instigated on operation of switch 22, and operation of the condensing unit motor I4 is instigated on operation of switch 23. The switch operating coils 25 and 21 are energized from a circuit including the secondary of the transformer 2| which is connected between the supply line conductors 39 and 42, and this circuit is controlled by the thermostatic switch 20 and the timing device 24.
One side of the secondary of the transformer 2| is connected by means of a conductor 36 to one contact of the thermostatic switch 20. The other contact of this switch is connected by means of a conductor 41 to one end of each of the switch operating coils 25 and 21. The other end of the switch operating coil 25 is connected by means of a conductor 48 and a conductor 49 to the other side of the secondary of the transformer 2|. It
will now be understood that the switch operating coil 25 is energized when the thermostatic switch 20 is closed. The other end of the switch operating coil 21 is also connected to the other side of the secondary of the transformer 2| by means'of a conductor 59, a normally open contact 28 of tors 48 and 49. the switchcoil 21 will not be energized upon closing ,of the thermostatic switch 20 until its circuit is closed by some other means.
This other means is the switch contacts 32 and 33 of the timing device 24. The contact 32 is connected by means of a conductor 5| and the conductor 49 to the secondary of the transformer The contact 33 is connected by means of a conductor 52 to the switch operating coil 21. It will now be understood that the operating coil 2'l will be energized'when the timer contacts 32 and 33 are closed. Since operation of the timer 24 is instigated upon closing of the thermostatic switch 20, as hereinafter described, the timer contact 32 may be rotated by means of the knob 34 to a desired position, so that it is not contacted by the rotatable contact 33 until after a .time interval of operation of the timing device. Therefore, the solenoid switch 23 does not operate until this predetermined time interval after operation of the solenoid switch 22 which operates immediately upon closing of the thermostatic switch 20.
One terminal of the timer motor 3| is connected by means of a conductor 53 to one side of the supply line 39. The other terminal of the timer motor 3| is adapted to be connected to the other side 42 of the supply line by way of two parallel paths. One path includes a conductor 54, the normally closed contact 30 of switch 23, a
conductor 55, a conductor 56, the normally open contact 26 of the switch 22, and the conductor 45. The other path includes a conductor 51, the limit switch 35 of the timer 24, a conductor 58, conductor 56, contact 26 of the switch 22, and conductor 45. It will now be understood that the timer motor 3| can operate only when the switch contacts 26 are closed, that is, when switch 22 is operated, and this occurs upon closing of the thermostatic switch 20. It will'also be understood that operation of the timer motor 3| ceases, even though the switch contact 26 be closed, when the switchcontacts 30 and 35 are both open.
I will now describe the complete cycle of operation. Assuming that the temperature of the air in the refrigerator enclosure I0 is within the desired limits, the thermostatic switch2|l is open,
" no parts are in operation, and the timer 24 is inits initial or normal position. These conditions are illustrated in Fig. 1. This is an idle period. Due to new of heat into the refrigerator enclosure ID, the temperature of the air increases in this enclosure until it reaches the predetermined upper limit. Thereupon; the thermostatic switch 20 closes to energize coil 25 of the switch 22. Operation of switch .22, that is, closing of contact 26, initiates operation of the electric fan I9. Circulation of air over the refrigerator coil produced by operation of the fan l9 causes any frost or condensed moisture which may have been formed on the doll II to evaporate into the air stream, thus increasing the humidity of the air. Operation of the switch 22 also instigates operation of the timer 24. Thereupon, contact 33 starts to move toward contact .32, and the switch arm 36 releases the contacts 35 to their closed position. In Fig. 2, the thermostatic switch 20 has closed, the first solenoid switch 22 has operated, the fan 9 is causing circulation of air in the enclosure l0, and the timer ing unit motor places the refrigeration apparatus in operation to cool the airbeing circulated by the fan l9.
At the same time opening of the contacts 39 of the switch 23 places control of the timer motor circuit upon the limit switch 35 of the timer 24. Also, closing the holding contacts 28 of the switch 23 bridges in a parallel circuit the timer contacts 32 and 33 so that the latter may now open and the switch 23 remain energized. The timer 24 continues to operate until the arm 36 has made a complete revolution and returns to its position shown in Fig. 1, whereupon the switch 35 opens the circuit of the timer motor 3| and the timer again becomes inactive. The switches 22 and 23 remain closed, continuing operation of the refrigeration apparatus and the fan, until the temperature of the air in the refrigerator enclosure I is decreased to the lower desired limit, whereupon the thermostatic switch 20 opens the energizing circuit of the switches 22 and 23 which open and thereby terminate the operation periods of the refrigeration apparatus and-the fan. Elie control circuit is again in the condition illustrated in Fig. 1.
It will be understood that various changes and modifications may be made within the scope of the invention as indicated by the following claims.
What I claim is:
1. Air cooling apparatus including an evaporator for absorbing heat from air to be cooled, \a compressor, a condenser, said compressor, condenser and evaporator being operatively connected to form a refrigeration system, a motor for driving the compressor, a fan for directing air to be cooled in thermal contact with said evaporator, a motor for driving said fan, and,
means responsive to temperature of the air to be cooledfor controlling operation of said motors and including adjustable means for delaying starting of said compressor motor a predetermined time interval after starting of said fan motor.
2. An air cooling system including refrigeration apparatus having a cooling element and operated by an electric motor, a blower operated by an electric motor for circulating air in thermal contact with'said cooling element, a first switch for controlling operation of said blower motor, a second switch for controlling operation of .said refrigeration apparatus motor, means for operating said switches responsive to temperature of the air to be cooled, and adjustable means for delaying closing of said second switch a predetermined time interval after closing of said first switch.
3. Air cooling apparatusincluding an evaporator, a condenser, a compressor driven by an electric motor, a blower operated by an electric motor for circulating air in thermal contact with said evaporator, a first solenoid operated switch for controlling said blower motor, a second solenoid operated switch for controlling said compressor motor, an adjustable delayed closing switch for controlling said second solenoid operated switch, and a thermostatic switch responsive to temperatureof air to be cooled for controlling energization of said first solenoid switch and said time delay switch and de-energization of both of said solenoid operated switches.
4. In a method of cooling air which includes causing circulation of air to be cooled in thermal contact with a cooling element.operating at a temperature such that frost may be formed thereon by condensation and freezing of water vapor in the air, that improvement which consists in intermittently circulating cooling fluid through said cooling element and intermittently causing circulation of the'air to be cooled, both responsive to temperature of the air to be cooled, and instigating circulation of the air different time intervals prior to instigation of circulation