US2027245A - Refrigerating apparatus - Google Patents

Description

.I an. 7,

J.v J. NANCE REFRIGERATING APPARATUS originl Filed Aug. i4, 1930 s sheets-sheet 1 04,59. l la 62 42 7 l f2? O "35.2.22 Mm.

HIS ATTORNEYS.

Jan'. 7, 1936- J. J. NANCE i 2,027,245

` REFRIGERATING APPARATUS Original Filed Aug. 14, 1930 3 Sheets-Sheet 2 J. J. NANCE I 2,027,245

REFRIGERATING APPARATUS Jan. 7, 1936.

Original Filed Aug. 14, 1930 3 SheetS-Sheet"3 INVENTOR wm JMA/Cf. I BY HIS ATTORNEYS.

Patented Jan. 7, 1936 UNITED STATES PATENT OFFICE nErmGEnATmG APPARATUS James J. Nance, Dayton, Ohio, assignor, by mesne assignments, to General Motors Corporation, a

corporation o of Delaware Application 14 Claims.

This invention relatestorefrigerating systems and more particularly to the mechanism for controlling the temperatures produced'by refrigerating systems. l

In refrigerating'systems it is customaryto provide some means for maintaining thetemperature within the evaporator or within the com-- partment which generally houses the evaporator, x

substantially constant. For instance, in compression systems, that is systems using a motor driven mechanical compressor or pump, this is generally accomplished by starting and` stopping the motor, and consequently the compressor, at predetermined high and'low temperature limits.

' In absorption machines, on the other hand, this is compartment to be cooled or to the temperature or pressure within the evaporator.

Frequently, however, it is desirable to provide means in conjunction with the refrigerating system for obtaining a temperature below that normally maintained in the evaporator or withinthe compartment to be cooled. For instance, in the freezing of water, sherbets, and-the like, the freezing is more rapidly accomplished at a temperature below that nornally necessary for maintaining food stuffs in a refrigerated condition. To this '.end, the so-called Cold control has been provided, consisting of means for temporarily changing theoperation of the snap switch to produce a lower average temperature for a predetermined number of cycles of operation or periods of operation of .the compressor, after which cycles the means functions automatically to reset the apparatus to itsnormal operation. A typical example of such a Cold control is shown in the patent to King. No. 1,658,342, Febru'ary'7, 1928.

v t It has'been.found,`however, in the-use of al Cold control such as disclosed in the patent to King,l that cycles of operation of the compressor frequency vary over wide lranges of time. -For instance, one cycle of operation of the compressor may take a considerable length of time due to the necessity of removing a large amount f August' 14, 1930, serial No. 475,179 Renewed July 11, 1934 i Consequently, in the use of such a Cold control which is adjusted to maintain a lower than average temperature for a predetermined number of cycles'or periods of operation of the compressor, it frequently happens that'the apparatus operates under this reduced setting of the Co1d`control for a period of time much longer or much shorter than necessary to accomplish the results desired.

It is to apparatus for overcoming these objectionable features that my invention particularly relates, having for one of its objects apparatus or mechanism operating in conjunction with the refrigerating system for modifying the operation thereof` or, in other words, to produce a lower temperature within the evaporator for a substantially definite period of time and independent of the number of cycles orperiods of operation of the compressor or generator or generator-absorber.`

Another object of the invention is to provide an improved control mechanism for a refrigerating system of the type in which the control mechanism is provided for maintaining a predetermined mean temperature in the cooling unit thereof, having means which can be actuated at will to modify the operation of the system temporarily to produce a dinerent mean temperature of the cooling unit for a definite predetermined interval of time and to thereafter automatically restore the system to the normal control of the T control mechanism.

' mined temperature limits and to provide an auxiliary arrangement in the control mechanism which may be operated so as to give a considerable range of modifications of the temperature limits normally supplied by the control mecha-- -nism and to automatically restore the normal -contro1 of the mechanism from either of the positions which modify the temperature limits after a predetermineddenite interval of time.

Further vobjects and advantages of the present invention will be apparent from the following description, reference being -had to the accompanying drawingswherein a preferred form ofthe present invention is clearly shown. In the drawings:

Fig. 1 is a refrigerating circuit embodying the improved control device of the invention;

Fig. 2 is 'a front view of the improved control 55 device;

i .I Fig. 3 is a top view of the improved control deg the control;

vice having the cover thereof removed and show-` ing a portion of the control in section;

Fig. 4 is an enlarged view taken on the lines I 4 4 of Fig. 3 showing a portion of the control in a position tomodify operations of the refrigerating system;

Fig. 5 is an lenlarged view taken on the lines 5 5 of Fig. 4 showing a stop member;

Fig. 6 is an enlarged View of a portion of the control device taken on the lines 6 6 of Fig. 8 showing a spring for automatically actuating the control into normal position;

Fig. '1 is an enlarged view of a portion of the control device taken on the lines 1 1 of Fig. 3 showing the connection of the time` device with Fig. 8 is a view of a portion of the c ontrol device similar to Fig. 3 showing the control in a released position ready to be actuated into normal position;

Fig. 9 is a side View taken on the line 9 9 of l sired to maintain normally a predetermined temperature in a refrigerating element or evaporator.'

In the form of apparatus chosen for illustrating the preferred embodiment of the invention, the refrigerating ,element comprises an evaporator or cooling unit I0 to which a number of contacts I I are attached in-circulatory relation. Any suitable refrigerant, such as sulphur dioxide, is supplied to this elementV by means of a compressor I2 which forces the refrigerant into condenser I3 and thence into a-receiver I4 from which it passes from pipe I5 through a oat controlled valve, not shown, -into the evaporator I0. The refrigerant, after boiling off in the evaporator I0 and coils II and performing its refrigerating effect in the well known manner, is circulated to the compressor through pipes I6 and I1. A suitable mechanism is provided for controlling the operation of the system, and, -for the purpose of illustrating the invention, it is shown herein as a switch which is `responsive to pressure conditions' prevailing within the evaporator or cooling unit I0. `This switch may have a flexible orV expansible chamber I8, such as a metallic bellows, the movement 'of which, in response to the pressure variations in the system, causes the making and breaking of an electric circuit at the point I9 so as to start and stop4 the motor 20 which is used for driving the compressor.

- In the control mechanism,` the bellows I8 is contained within a mounting guard 2| `and has' its upper end 22 secured toa lever 23 which is pivoted at 24. The opposite end of lever 23 extends intoa bracket 25 and has a'lever 26 piv- 'oted thereto by a stud 21. 'I'he lever 26 has a cam mounted at one end thereof engaging a spring pressed roller 29 which provides a snap action` mechanismfor quickly moving an electric contact 30 into or `out of engagement with a simi- ,'larA contact r'30a located therebelow. The lever 23 therefore serves as a means for moving the electrical contact 30 upwardly with respect to the contact 30a in response to movement of the measure resoonsive element or bellows Il. The

v cycle of the system. Likewise, if the' resistance -present invention and consists in placing a recontact 30 is secured to an arm 3I pivoted at 32 and having its other end attached to the lever 26 by an insulating link 33. A stud 34 `passes through the lever 26 and through the link 33 to hold these parts together and extends upwardly 5 a great distance from the lever. The bellows, levers, and other parts are all mounted upon a base 35 to which a threaded stud 36 extends and has springs therearound which abut the base 35 and provide adjustment for the control device. m Under normal operating conditions the bellows I8v is adapted to be expanded or contracted in response to pressures within the system for actuating the lever 23 up and down. This movement causes the cam 28 secured to the lever 26 15 to force the spring pressed roller 29 upwardly, thus permitting the'cam to travel to the opposite side of the roller. When this movement occurs a snap action isimparted to the lever26 which causes the movable contact 3.9 to quickly engage 20 'or disengage its operating stationary contact. In

this manner the motor of the system is started and stopped to cause the compressor to cyclically withdraw refrigerant from the evaporator. The foregoing mentioned parts of the control device 25 are identical to and operate in the same manner as the control device shown in the patent to Otto M. Summers, No.' 1,819,979, issued August 18, 1931. y y

'I 'he apparatus is usually adjusted at the fac- 30 tory or in the field by a serviceman for such normal operation by suitably tensioning the springs which surround the stud 36 and in such condition the lever 23 will have its upward and downward movements resisted so that Ait will open or close 35 the circuit of the driving motor 20 only at the maximum and minimum pressure-temperature points for which the tension corresponds.

v the serviceman in the'Y eld. This can be accomplished by interposing a resistance tothe downward movement of the lever 23,*the operation of the switch contacts thus being delayed so that the system will continue operating for a longer period of time, thereby prolonging the freezing to the downward movement of the lever 23 is increased it will require a. greater effort onthe part of the diaphragm or bellows I8 to pull the lever down into contact breaking position (the descent of lever 23 causing the raising of contact 30 away from its corresponding stationary contact 30a, thus breaking the circuit).

A suitable method of interposing such a resistance is illustrated in the embodiment of the silient obstruction in the path of the downwardly moving lever 23. A spring 31 is used for Vthis purpose and in the preferred embodiment `of the invention the spring 31 is coiled and hooked into and carried by a slotted shaft 38 so arranged that one end 39 of the spring 31 pro- -jects while thel body of spring 31 is forced to rotate with the shaft 38 when same is turned. The pin or stud 21 extends outwardly from lever 23 and is engaged by the spring 31 in such a manner that when the lever 23 descends, the pin 21 engaging the spring leg 39 will have its downward movement resisted tp an extent corresponding to the degree to which the spring 31 is wound:

The spring 31 carried by the shaft 38 may 'oe 75 rotatedandwound up so that a correspondingly greater tension is caused to bear against the downward movement of 'lever 23. Thus, if the spring is wound in the position indicated by the arrow beneath the"Co1der as shown in Fig.

2 more and more tension may be exerted against the descent of the lever 23. Various degrees of tension may be secured, ranging from a maximum to a minimum and while any intermediate point between these extremities may be selected as a position at which to station the spring or wind the spring, in adevlce suitable for manipulation, it is preferable to have a selected series of stations to which the spring may be wound.

Thus, as shown in Fig. 2, the front 4| of casing -42 is provided with a dial 43 having points represented by numbers at which the spring may be stopped in its rotation or winding. The shaft 38 which carries the spring 31 is rotated in turn by an operating handle orknob 44 secured to a shaft and held in any position by a spring 46 compressed between .the wall ,4I of casing 42 and a plate 41 when the knob 44 is released and pushed inwardly. The plate 41 is secured to the shaft 4,5 so that itwill rotate therewith and is provided with an extension having a button 48 secured' thereto.l The button 48 is adapted to be forced into' any of the holes 49 provided -in plate 5I which is mounted on the bottom of casing 42 by screws 52. It is to be understood that the holes 49 are located in alignment with the points designated by the numerals on the dial 43'.

The resilient modifying device just described is so arranged that, when the knob or handle 44 is pulled out and turned to cause the leg 39 of' spring 31 to be in the path ofthe downward movement of lever 23, 'a maximum resistance is interposed to the descentof thelever-23. This position is shown in Fig. 3 where the spring carrying shaft handle or knob 44 is in the number.6 operating position. It is evident that anappreciable drag is presented to the lever 23. The resultof this retardation of the downward movement of lever 23 will be to, cause the prolongation of the freezing cycle, in other words, .a longerthan-normal operationofthe compressor.

i Itis evident that the duration of this longerthan normal operation of the compressorwill be decreased as the spring is further untensioned,

thatis, as the spring-carrying shaft land handle '44 is moved to successive positions in the clockwise direction opposite thatindicated bythe o 'arrow beneath the word Colder in Fig. `2.

from arm26 and istherefore ineffective while the V After the refrigerator has been in operation for an appreciable period, a considerable amount of .frost will collect around the coils and act substantially as an insulator.

\ 'In order to defrost the refrigerating element,

it isnecessary to shut down vtheoperation or discontinue the operation of the compressor and this is effected by completely blocking the movement'of the control mechanism as by interposingjan obstruction to the downward movement of the lever 26. For this purpose a blocking arm 54 is rigidly mounted onthe spring carrying ar' rangement shown in Fig. 3. This arm 54 is normally entirely out of the path of the pin extending refrigerating system is in operation and while-the resilient modifying device is in any of its eilecr tive positions. By pullingout handle 44 a great'- er distance than is ordinarily required to 'moveI thev plate l41, thebutton 48 will then clear the;

stop pin 56a, stationarily mounted Ion plate 5|,

and. thezhandle- 44 can then be moved in an oppopin.

site direction to the arrow shown in Fig. 2 to the position marked Defrost as shown in Fig. 2 so as tolengage the underside of the pin 34. The apparatus will continue to defrost since the arm 54 arrests the downward movement of arm 26 by 5i knob 44 is set into any of the positions to cause longer than normal operation of the compressor, henceas shown in Fig. 3 the knob is in No. 6 position and of course the arm 54 is disposed in 20 a plane above the pin 34 but does not engage the The dotted -lines in Fig. 4 show the plate 41 and button 48 in number I, or normal, position of the switch and corresponds to Fig. 2 except that 25 it is a cross section immediately behind the front wall 4l of casing 42. vThe full line position in 4 shows the switch in its Colder, or number 6, position, and corresponds to Fig. 3.

The following described parts and their operto performthe desired results without departing from the invention which I am about to describe. For instance, these parts may all beconstructed substantially similar to the construction 35 shown in the Summers patent heretofore referred to but assembled in a different manner.

Manufacturers of refrigerating apparatus have experimented with and determined 'approximate- 1y the length of time required to freeze at a cer- 40 tain predetermined temperature such substances as water, ice-cream, sherbets, and the .like and are at present publishing booklets containing various recipes for concocting such substances, to-

. gether with instructions for placing'and leaving 45 the arm or .pointer of the so-called Cold control 'in certain positions to modify the operations of the apparatus to produce a lower temperature before manually returning the pointer to normal position. The user of a' Cold control of this 50 type is always confronted with such hazards, for example, as that of freezing everythingcontained in .the cooling compartment of the refrigerator due to the low temperature produced by the 'evaporator which will occur should they forget 55 to return the pointer of the device back to normal position.

It isftherefore an object of this invention to provide,means for eliminating such hazards in refrigerating 4apparatus l and I have provided 60 means whereby the apparatus heretofore de;-

scribed canbe combined with a mechanism for automatically returning the handle or knob 44 and th parts connected therewith for modifying'the control device to 'normal position or`to65 the position designated by the numeral l on the dial 43 shown in Fig. 2. 'To this end I provide a member 56 extending through an opening in the rear wall of caging 42 Landinto which the shafts 38 and 45 extend andare connected together by ,70 a sliding connection 51-.` The member 56 is pro- `vided with a pin 58 and is held in acertain position by` the screw-.59 which passes through thewall of casing 42. 4Member 56 is provided with a camming surfacel which is engaged by the roll- 80. ation can be constructed in any suitable manner* 63 which surrounds the shaft 45 and has its 'opposite en'd 64 connected, by a pin 65, mounted near the outer circumference of a wheel 66. Wheel 66 is journaled on a shaft of a clock or chronometric timing device, the mechanism. of v which is not shown. The chronometric timing device may be. anordinary alarm clock or the like which has a spring wound alarm mechanism adapted to be released at a certain predetermined time to cause rotation of the wheel 66. The roller 62 also engages a circular plate 1l loosely mounted upon the shaft 45 and adapted to abut a'shoulder 12 provided on shaft 45.. A coiled spring 13 surrounds thesliaft'd and has one end thereof secured to the shaft 45 and has its other end secured to a pin 14 mounted on plate 5l.- This spring 13 is wound to a predetermined tension` and is arranged to resist-the move-:-

ment of the handle or knob 44, in the directioh shown by the arrow beneath Colder in Fig. 2, before it has its ends permanently secured. Thus, the arrangement of spring 13 provides a means for rotating the shaft 45 and knob 44 when the timing device releases'to cause movement of roller 62.

The timing device, which may be `an alarm clock, is secured to and within the casing v42 by a face 16 having the usual hour and minute hands or pointers cooperating with numerals for designating time. j of numerals on the face 16 having a hand'or pointer cooperating therewith for designating the time at whichthe alarm mechanism may be set to release. A stem 11 may be'utilized for moving the hour and minute hands or pointers -of the time device. Another stem 18 may be utilized forimoving the hand or pointer to any desired position of the second series of numerals toindicate the'time at which the alarm should release. The key 19 may be employed for winding the time device. Another key 80 may be uti- 'lized for winding the alarm mechanism. The

time device mechanism and other parts associated Vtherewith are all contained within the casing 42, which casing is secured to the -base 35 of the control by brackets 8l and screws 82.

In order to protect the control, a sheet metal cover 83, see Fig. 2, is provided. This cover has openings or slots in its side wall, (not shown), to provide means whereby the cover may be placed on the control without striking. the brackets i 8l and the member 56. Suitable locking means or retaining means include the catches 84 secured to springs 85, which springs are in turn fastened tostuds 86 mounted on the base 35. Catches 84 have an outwardly extending mem- ,ber or hook which enters an openingin the cover 83 and removably secures the cover on the base. In this manner it is evident that the control device may be inspected and, if necessary,

adjusted without dismantling the same.

' Having thus described various elementsy of my i improved apparatus, the operation of the mechanism to automatically restore the auxiliary adjustment device to normal position, or position indi :ated by the numeral I on dial 43, will nowbe explained. I'n order to set the device to any position to resist the downward movement of lever 23 or to modify the pressures at which the control is adapted to be actuated, the knob or handle 44 may be pulled out sufficiently to remove the button 48 on plate 41 from the opening or hole 49 located in plate 5I. The knob 44, shaft 45, plate 41, and spring 31 can be rotated in a coun- There is also a second series terclockwise direction into any of the positions for causing longer than normal operations of the compressors. After the plate 41 has been moved into any of the positions indicated on the dial 43 thisplate el can also be moved back in a clockwise direction to any of the other positions designated by the numerals, of less value; on dial 43, that is from number 6 position in Fig. 3 to any of the positions indicated on dial 43 if desired. During this movement the spring 46 will be compressed and will .apply suilicient tension upon the shaft 45 to cause the shaft 45, knob 44, and end plate 4l to move inwardly when released. It is'therefore apparent that the knob 44 can be manually moved back from position No. 6 to any of the other positions indicated on the dial 43 (see Fig. 2) after the device has been "set without hindering the operation of the mechanism, for automatically restoring the auxiliary vadjustment device to normal position. Thus, the

spring 46holds'the button 46 in engagement with any of the holes 49, located in plate 5l, at which the knob is set to permit spring 3l to be placed in the downward path of lever 23 thereby increasing the spring tension which the lever 23 must overcome before actuating the electric contact 36 to interrupt the electric circuit to the motor 20. In this manner the motor 26 will be caused to actuate the compressor I2 a longer period of time than ordinarily required to Aproduce a lower temperature in the evaporator. Itis to be understood that the sliding connection 5l of shafts 38 and 45 permit the knob 44 and shaft 65 to be pulled outwardly without moving shaft 38 and parts mounted thereon. 'I'he .wheel 66 will be automatically returned to a position rendering it capable of moving the yoke 63 and roller 62 sideways, or to the left as viewed in Fig. 3, by engagement of roller 62 with plate 1i, which plate will be forced inwardly by the spring 46 when the device is set in any of the positions indicated on the dial 43 other than No. 1" and Defrost. The alarm mechanism may be arranged so that the wheel 66 will rotate only' sufciently to moveroller 62 until it strikes the stop pin 58. Thus, the roller remains on the camming surface 6l of member 56,I so that it will be in position to always be reset or forced to the bottom of the camming surface when the device is actuated into any of the positions except normal operating position. After the 'device has been actuated into any of the various positions, to

cause the compressor to operate longer, the

. device may then be set to automatically return of cycles the apparatus makes during such pre-l determined time. In order to accomplish the automatic return of the device to normal position the stem 18 is actuated to set the alarm mechanism so that it will release after adenite predetermined interval of time. This can be indicated by the small pointer on the face 16 of the clock, together with pointers indicating hours and minutes of time. The key 88 is then actuated to wind the alarm mechanism to insure its operation at the time for which it has been set to operate the release. When the desired interval of time has elapsed the alarm mechanism will release causing the wheel 66 to rotate. Rotation of wheel 66 causes the yoke 63 carrying roller 62 to move sideways and the roller moves upwardly on the caming surface 6I of member 56. Engagement of the roller 62 with plate 1| which 2,027,245 t abuts the shoulder 12 n shaft 45 causes shaft this direction until the pointer on knob 44 reaches no!A veo

' the colder positions.

normal position orl until the extension of plate 41 which carries button 48 comes into engagement with stop pin 56a, seeFig. 4. The wheel 66 is 'adapted to remainin its released `position until the device is `reset, therefore the roller 62 prevents the button 48 from lentering any of the openings 49 during rotation of plate 41. Rotationof shaft 45 will thereby be' stopped by its engagement with lpin 56a and the spring 46 will then force button 48 into the opening or hole 49 in plate 5I directly opposite normal position. Rotation of wheel 66, which rotation is caused by movement of yoke 63, in a direction to the right as viewed in Fig. 3 of the drawings, when the roller 62 is set into its position to release button 48 at a certain time, will tend to vturn the alarm mechanism of the timing device. t isV there- .fore desirable to provide means on the shaft of wheel 66 which will permit wheel 66 to be rotated in one direction without disturbing or rotating the alarm mechanism of the timing device such as when the apparatus is being set into any of I Such a means lcan be in the form of a ratchet that rotation of the Wheel 66 by the alarm mechanism in one direction will move the yoke 63 and roller 62 while movement of the yoke 63 in an opposite direction will not disturb or rotate the alarm mechanism of the time device. Ratchet arrangements ofthe type described are wellknow`n inl their respective art and it is believed to be unnecessary to illustrate how such a conventional arrangement vcan be applied to theapparatus disclosed. It is to be understood that instead of using an alarm 4clock mechanism, a

ldevice whichA could be set for a predetermined refrigerator and also provided with means for defrosting said evaporator at will.-

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

What is claimed is as follows:

1. A refrlgerating system comprising in combination, a cooling element, means for circulating a refrigerati'ng medium through said element, means for maintaining said element at a` normal predetermined average temperature, manually actuatable means for temporarily modifying said second named means to obtain a.

temperature of said cooling element different from the normal average temperature thereof,

arrangement connected* to I the shaft upon which the wheel 66 is mounted so.

and chronometrically operated means cooperating with said manually actuatable means and controlling the duration of effectivenessV thereof, said chronometrically operated means being operable independently of said rst and said second named means for automatically restoring the l system to normal operation.

2. A refrigerating system comprising in combination, an evaporator, means for withdrawing gaseous refrigerant from the evaporator to condense the same-and to circulate the condensed `refrigerant to the evaporator, and apparatus for controlling said means including mechanism for obtaining normally a certain average temperature of the evaporator, said apparatus including a selective setting device for selectively obtaining a plurality of different average temperatures of the evaporator, said apparatus also including "chronometrically operated means cooperating with said setting device and controlling the duration of effectiveness thereof, said chronometrically operated means being operable independently of said first named means and said controlling apparatus for automatically restoring said mechanism .to normal operating condition.

3. A refrigerating system comprising in combination, an evaporator, means for withdrawing gaseous refrigerant from the evaporator ,to condense the same and to circulate the condensed refrigerant to the evaporator, and apparatus including mechanism for cyclically starting and stopping said means automatically in response toI certain high and low temperatures respectively of the evaporator, a selective device for temporarily modifying the operation of said mechanism to :secure the starting of the cycles at a plurality of -Iselective lower degrees of temperature than normally required, said apparatus including chronometrically operated means cooperating with said device and controlling the duration of effectiveness thereof, said chronometrically operated means being operable independently of said first' named means and said apparatus for automatically restoring said mechanism to normal `operating condition, and said chronometrically operated means including means adapted to be adjusted for varying the time of modified cycles. f

4. A refrigerating system comprising in combination, a cooling u nit, means for cyclically circulating a refrigerant medium through said unit, control apparatus for controlling the circulating cycles of said means whereby to' cool said unit to `a predetermined average temperature, a selective device Afor temporarily modifying the cycles of operation of said means whereby to obtain a plurality of selective different average temperatures in said unit, chronometrically operated means associated with said modifying device for controlling the duration of effectiveness thereof, said chronometrically operated means being operable independently of said Viirstnamed means and said control apparatus for automatically restoring the system to normal operating condition.

5. A refrigerating system comprising in combination, a cooling unit, means for withdrawing refrigerant from the cooling unit for condensing the refrigerant and for delivering it again to the cooling unit, an apparatus for controlling said means including a pressure responsive element, electric contacts, snap action mechanism for said contacts, manual operating means normally independent of said snap action mechanism but operable to modify said snap action mechanism to vary the ,pressure at which said mechanism is responsive.' without disturbing the normal adjustment of said apparatus, and chronometrically controlled means cooperating with said manual operating means and operable independently of said iirst named means and said apparatus for automatically actuating said manual means out of engagement with said snap action mechanism after said manual means has been in engagement with said snap action mechanism for a predetermined periodV of time.

6. A refrigerating system comprising in combination, a cooling unit, means for withdrawing refrigerant from the cooling unit for condensing the refrigerant and for delivering it again to the cooling unit, an apparatus for controlling said means including a pressure responsive element, electri'ccontacts, snap action mechanism/ for said contacts, manual operating means normally independent of said snap action mechanism but operable to modify said snap action mechanism to .vary the pressure at which said mechanism is responsive without disturbing the normal adjustment of said apparatus, chronometrcally controlled means cooperating with said manualoperating means and operable independently of said first named means and said apparatus` for automatically actuating said manual means `out of engagement. with said snap action mechanism after said manual means hasy been :in engagement with said snap action mechanism .means for varying the time of effectiveness of said 8. Refrigerating apparatus including a refrig- 'y erant liquefying means and a refrigerant'evaporating means, control means for controlling the operation of the apparatus for providing a-normal refrigerating temperature, said control means including selective means for providing lower than normal refrigerating temperatures and selective means for providing higher than normal refrigerating' temperatures, one of said selective means including means for retaining it in modified position to provide a modified temperature and thereafter returning it to normal position to again provide normal. refrigerating temperatures. f

9. Refrigerating apparatus including an evaporator, means for circulating a refrigerant through said evaporator, control means for controlling said circulating means, saidfcontrol means having a normal action operation to control said circulating means to maintain a normal refrigerating temperature in said evaporator, means associated with' said control means for varying the `normal controlaction of said control means-to erant liquefying and evaporating means, control provide a lower than normal temperature in said evaporator, means associated with said control .means for varying the normal control action of said control means to produce a higher than normal temperature in the evaporator, one of said 5 means associated with the-control means being rendered inoperative after performing its function to thereby permit the control means to automatically return to itsk normal control action.

10. Refrigerating apparatus including a refrigerant liquefying means and a refrigerant evaporating means, control means for controlling the operation of the apparatus for providing normal ice freezing temperatures whereby frost accu` mulates upon the evaporating means, said'control vl5 means including selective means for providing lower than normal freezing temperatures and selective means for providing temperatures above ice freezing temperatures to melt frost from'the evaporating means, one of said selective means 20 being automatically operative to return the ap- -paratus to normal ice freezing temperatures.

11. 'Refrigerating apparatus including a refrigerant liquefying means and a refrigerant evaporating means, control means for control- 25 ling the operation of the apparatus for providing a normal refrigerating temperature, said control means including selective means for providing lower than normal refrigerating temperatures and selective means for providing higher 3o than normal refrigerating temperatures, one of said selective means being rendered inoperative automatically after a predetermined time to return the apparatus'to normal refrigerating temperatures.

12. Refrigeratingapparatus including a refrig erant liquefying means and a refrigerant evapo. f

rating means, control means for controlling the operation of the apparatus for providing normal ice freezing temperatures whereby frost accumu-40 lates upon the evaporating means, said control means including selective means for providing rlower than normal freezing temperatures and selective means for providing temperatures above ice freezing temperatures to melt the frost from 45 the evaporating means, one of said selective means being rendered inoperative automatically wherebyA to return the apparatus to normal ice "freezing temperatures.

13. Refrigerating apparatus including refrigerant liquefying and evaporating means, control means for controlling the operation of the apparatus to provide ka normal refrigerating temperature, said control means including chronometrically controlled means forl varying the refrigerating temperature,. said chronometrically controlled means including selective meansfor providing different temperature variations from. the normal refrigerating temperature..

14. Refrigerating apparatus including ,refrigmeans for controlling the operation of the apparatus to `provide a normal-refrlgerating temperature, said control means including meansl for providinglower than normal refrigerating '65 temperatures and. means for providing higher than normal refrigerating temperatures, `vland chronometric means for. controlling one of said two last mentioned means.

JAMES J.NANCE. 70'

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