US1877967A - Refrigerator control - Google Patents

Description

P I932- E. c. RANEY 1,877,967

REFRIGERATOR coNTRoL Filed April 29, 1932 awn? He l .1502! C. Qameg;

. I v MM Patented Sept. 20, 1932 UNITED STATES ESTEL C. RANEY, OF COLUMBUS, OHIO REFRIGERATOR CONTROL Application filed April 29,

My invention relates to Control systems for controlling the cyclic operations of refrigerators to produce perlodic defrosting to prevent more than the formation of a slight amount of frost on the surfaces of the cooling units of refrigerators and thus produce a greatly increased refrigerating etficiency. I

The object of the invention is to provide an automatic control device which not only maintains refrigerating temperatures at desired values, but also periodically raises the temperature of the cooling unit of the refrigerator sufiiciently to defrost the refrigerator and then restores it to the refrigerating tem eratures. The invention also'has for its 0 ject to provide a means for adj usting the refrigerating mean temperature without affecting the periodic defrosting temperature, the adjusting means being so compensated that the defrosting high temperature limit will remain practically constant regardless of the. adjustment of the refrigerating temperature range of the refrigerator.

Thus, by my invention, I provide a defrosting means that will enable initiation of the defrosting cycle at any desired temperature and a means for adjusting the refrigerating temperatures without affecting the high temperature limit occurring at the end of the defrosting cycle.

My invention also provides a switch mechanism or means for opening and closing the circuit of the motor that drives the compressor of the refrigerator in response to the changes in the refrigerating and defrosting temperatures and also in response to the flow of a current that, if continued, would injure the motor that drives the compressor of the refrigerating apparatus.

The invention also provides means for closing the circuit of amotor used to operate a compressor at desired temperatures and for opening the circuit at lower temperatures. The closing temperatures may be mitted during said periods.

RElSSUtLD above or below 32 F. ornormal water freez- 1ng temperature. The opening and closing 1932. Serial No. 608,159.

temperatures are maintained for periods of time separated by intervals during which the switch mechanism or means maintains the circuit open to permit a materially greater rise in temperature than that per- This is accomplished by a suitable resistant device that at intervals resists closing movements of the switch mechanism produced by a pressure device and enables removal of frost or water that gathers on the refrigerating unit.

The invention consists in the provision of other features that will appear from the following description and upon examination of the drawing. Structures and systems containing the invention may partake of different forms and still embody the invention. To illustrate a practical application of the invention, I have selected a system containing my invention, it being understood that variations may be made without departing from the spirit of the invention. The par"- ticular system and parts of the structure, selected as illustrating an embodiment of my invention, are described hereinafter and shown in the drawing.

Fig. 1 illustrates parts of the structure embodying the invention and shows diagrammatically the system formed by connecting the parts. Fig. 2 illustrates parts of the switch mechanism for controlling the circuit of the motor.

As shown diagrammatically in the drawing, a refrigerator 1 is provided with a cooling unit 2. A compressor 3 operates to circulate a refrigerant medium through the cooling unit 2 to reduce its temperature in the manner well known in the art. The compressor 3 is driven by a motor 4 that is subject to the control of a switch mechanism 5. The switch chanism 51 is operated by the changes in mperat'ure of the cooling unit 2 and by an excess flow of current through the motor 4.

The motor that drives the compressor of the refrigerating apparatus is controlled by the temperature produced by operation of the compressor by the motor and also by the flow of the current in the circuit of the motor. A bellows 10 is connected to a suitable bulb 12 by a tube 11. The bulb 12 is located in close heat transferring relation with the cooling unit 2 of the refrigerating apparatus. The gas in the bulb and in the bellows varies in pressure as its temperature changes, particularly that portion in the bulb. The pressure of the gas in the bellows 10 operates through the lever 15 to open and close the switch mechanism 5. The lever 15 is pivotally supported on a suitable pin 16, and is provided with a snap switch arm 17 that is drawn by means of a spring 18 into a notch 19 formed on a part of the lever 15. The spring is also attached to a bar 20 that has one end located in a notch 21. The spring 18 operates to hold the ends of the bars in the notches 19 and 21. Vhen the pivoted ends of the bars, that is the ends located in the notches 19 and 21, pass the spring 18, when moved in either direction, the spring 18 operates to open or close the switch mechanism 5.

To enable adjustment of the responsiveness of the bellows, a spring 24 is connected to the lever 15 and to a plate 25 so as to draw the lever 15 against the end of the bellows and to resist the expansive movement of the bellows. The spring 24 thus cooperates with the bellows to move the lever 15 on the pivot pin 16. A contact member 26, forming a part of the switch mechanism 5, is connected to one end of the bar 17 and is adapted to electrically connect the fixed contacts 27 and 28. When the lever 15 is depressed by the operation of the spring 24 upon the contraction of the bellows 1 to cause the pivot point of the bar 17 to pass the center of the spring 18, the circuit through the switch mechanism will be opened at the points 27 and 28. The upward movements of the bars 17 and 20 are limited by suitable stops located on a pivoted arm 30. The position of the ann 30 may be adjusted by a screw 31 to locate the bars 17 and 20 in position so that when the lever 15 is raised and the pivot points of the bars 17 and 20 pass the center of the spring 18, the movable contact 26 will be snapped downwardly so as to close the circuit of the motor 4 between the points 27 and 28. This operates to close and open the circuit of a motor that drives the compressor which circulates the refrigerant medium through the cooling unit 2 according to the temperatures produced by the cooling unit. I

By the repeated cyclic operations of the compressor, due to the opening and closing of the circuit of the motor, the moisture that condenses and freezes on the cooling unit 2 gradually accumulates as frost and to defrost the cooling unit, I have provided means for periodically preventing closing of the circuit of the motor at the points 27 and 28 until the temperature of the cooling unit has raised sufiiciently to cause the frost to melt and prevent an accumulation of more than a film of frost.

To produce periodic defrosting I have provided means for increasing the resistance to the expansive movement of the bellows at intervals separated by a predetermined number of cyclic refrigerating operations of the compressor and' to restore the control of the motor and the compressor to the refrigerating temperature control to produce the normal cyclic refrigerating operations. Increasing the resistance to the expansive movement of the bellows increases the pressure of the gas in the bellows requiredto move the lever 15 to operate the contact 26 and, consequently, the contact 26 will not open the circuit until the temperature of the cooling unit 2 rises to a point that corresponds to the total resistance to which the bellows is subjected. In order to produce an increased load on the bellows at times separated by a predetermined number of cyclic operations of the motor and the compressor, the lever 15 operates a member that is moved step by step and, when it is moved to a certain point, it operates to connect a resistant member that resists movement to close the circuit of the motor and will cooperate with the spring 24 that resists the expansive movement of the bellows 10.

In the form of construction shown, a ratchet wheel 34 is rotatably supported on a lever 35. The lever 35 is pivotally supported on a bracket 36 and the compression spring 37 is located intermediate the lever 35 and the plate 25 to which also the tension spring 24 is connected. The plate 25 is adjustably supported on a screw 38. The screw 38 is rotatably supported in a suitable frame or shell 39 and may be rotated by a knob 40 located on the outside ofthe shell. A suitable pointer 41 may be connected to the knob 40 and a stop 42 may be provided for limiting the adjustment of the screw 38 by means of the knob 40, while the pointer 48 is connected to the knob. Further adjustment may be made by the removal of the pointer 41 from the knob 40 and, if desired, the pointer may be reconnected to provide for limited movements of the screw 38 and limited adjustment of the plate 25. Since the spring 24 is a ten- A sion spring, and the spring 37 is a compression spring, adjustment of the plate 25 operates to increase the pressure of one spring and decrease the pressure of the other spring,

dependent upon the movement of the-plate 25.

The ratchet wheel 34 is operated by means of aslidably supported pawl 45 that is spring pressed by means of the spring 46 which opcrates to raise the pawl 45. The pawl 45 is supported by means of a pair of pins 47 located in a slot 48 formed in the pawl 45. The pins 47 operate to limit the movements of the pawl 45 by the spring 46 in order to limit the movement of the ratchet wheel 34 so as to produce a uniform step movement each time that the pawl is depressed by the lever 15. The pawl completes its operation when the lever 15 reaches the completion of its downward stroke, that is when it opens the circuit of the motor 4 at the points 27 and 28. This causes cessation of the operation of the compressor 3 and chilling of the cooling unit 2 immediately ceases. As the temperature of the cooling unit rises the bellows 10 then expands and raises the lever 15 and the lever 15 moves from the pawl 45 when the pawl has been raised by the spring 46 against the lower stop pin 47 Preferably, a suitable catch pawl 50 operates to engage the teeth of the pawl 34 as it is stepped around by the movement of the pawl 45. The catch pawl 50 is also spring biased by means of a spring 51 to hold the ratchet 34 in the position to which it is turned by the operations of the lever 15.

In order to subject the opening movements of'the bar 17 to the control of the ratchet 34, the lever 15 is-provided with a link 01' pivoted-arm 55 and the ratchet wheel 84 is provided with a projection 56 that at one point in the rotation of the ratchet wheel engages the arm 55 and, preferably, a projection 57 formed on the end of the arm. If desired, the end of the projection 56 may be made V-shaped to insure registration and engagement of the projection 57 when the lever 15 is raised subsequent to registration of the proections 56 and 57. When the arm 55 is thus engaged by the ratchet wheel, movement of the lever 15 is resisted by the spring 37 that is transmitted through the lever 35 and the ratchet wheel. The pressure in the bellows 10 must then be increased to overcome the pressures of the springs 37 and 24 in order to close the circuit of the motor. This requires a corresponding rise in the temperature of the cooling unit. When the temperature rises to this point the motor of the circuit is closed and the compressor lowers the temperature in the cooling unit of the refrigerator. When the temperature again reaches the normal low limit, as determined by the tension of the spring 24, the circuit of the motor 4 is again opened at the points 27 and 28 which will be at the high limit of the refrigerating temperature. When the lever 15 descends to open thecircuit of the motor, it operates the pawl'45 to move the projection .56 to one side 24. The ratchet wheel, in the subsequent cy-.

cl'ic refrigerating operations of the compressor, is then stepped around until the projections 56 and 57 again register whereupon the defrosting operation of the refrigerator is repeated. These timed defrosting operations reduce the frost accumulation and maintain a high refrigerating ellicienc'y.

The normal mean temperature of the refrigerator may be varied as may be desired by rotation of the knob 40 to vary the pressure of the spring 24. This, however, correspondingly varies inversely the pressure of the spring 37 with theresult that if the pressure of the spring 24 is decreased toallow a rise of the mean normal temperature of the refrigerating cycles, 'the high limit of the defrost temperature will remain substan tially constant, while, on the other hand, if the plate 25 isadjusted by the operation of the knob 40 and the screw 38 to decrease the pressure of the spring 24 and produce a lower range of temperatures by the cyclic operations of the motor and the compressor, the pressure of the spring 37 will be increased to maintain the said upper defrosting temperature limit. Thus, the control maybe adjusted to produce variations of the refrigerating temperature limits while the proper defrosting temperature occurring at separated intervals will be insured. By maintaining the upper limit of the defrosting temperature substantially constant and at a point that will insure the completion of the defrosting operation, the device will produce defrosting in the shortest possible time by the rise of temperature of the cooling unit.

The switch mechanism 5 will not only maintain the refrigerating cyclicoperations of the refrigerating apparatus and the periodic defrosting of the cooling unit, but also will protect the motor as against an overload. The switch mechanism 5 may be operated to open the circuit of the motor at the points 60 and 61 by the operation of an overload heat coil 62 which is connected in the circuit of the motor 4. The heat coil 62 surrounds a shell in which a fixed pin is inserted and to which is attached a ratchet 63. The ratchet is held from rotation normally by a low temperature melting solder interconnecting the shell and the pin. When the heat of the coil 62 exceeds a predetermined value,

the solder is melted so as to free the ratchet of the motor between the points 60 and 61.

The bar 71 is connected to a rocker bar 73 by a spring 7 4. \Vhen, therefore, the frame 65 is released by releasement of the ratchet wheel 63, the lever 67 is rotated so as to lower the one end of the bar 71 below the point of connection of the spring 74 with the rocker bar 73 and the spring 74 operates to raise the bar 71 and open the circuit of the motor at the points 60 and 61. This operates to swing the arm 70 of the lever 67 against the rocker bar 73 and lift one end of the rocker bar 73. The parts may be restored when the heat coil 62 and the solder have cooled sufficiently to fixedly hold the ratchet wheel 63 by manually moving the lever 67 The arm 69 moves the frame 65 against the tension of the spring 66 and the arm 70 raises one end of the bar 71 to raise the said end of the bar 71 above the spring 74. The spring 74 then causes the contact 72 to snap against the fixed contacts and close the circuit of the motor between the points 60 and 61. Assuming that the temperature of the refrigerator has raised sufficiently to cause the bellows 10 to close the circuit of the motor between the points 27 and 28, the motor 4 will immediately start the operation of the compressor 3 to lower the temperature of the refrigerator.

Thus, by my invention, I have provided a switch mechanism that will insure protection of the motor as against undue heating and injury and, at the same time, maintain eflicient operation of the refrigerator and eliminate the inconvenience of constant attendance to the defrosting which ordinarily occurs at very irregular intervals that results in the inconvenience occurring by reason of the excess accumulation of frost and the excess amount of water discharged in the defrosting operation.

I claim:

1. In a refrigerator control system, means for maintaining a normal operating refrigerating cycle between fixed temperature limits, means for periodically modifying the upper temperature limit, means for adjusting the temperature range of the normal operating cycle, a compensating means whereby the upper temperature limit of the periodic cycle remains at a practically fixed value regardless of adjustment of the normal operating cycle.

2. In a refrigerator control, a switch, a pressure means including a resistant member for operating the switch to normally maintain a substantially constant refrigerator temperature, a defrosting means including a resistant member for periodically raising the temperature at which the switch is closed by the pressure means, a member for invcrsely varying the effectiveness of the resistant members to vary the normal temperature of closing the switch by the pressure means and maintaining a substantially constant upper limit of defrosting temperature.

3. In a refrigerator control, a switch, a pressure means for operating the switch, means for periodically raising the refrigerating temperature at which the switch is closed and adjustable means for varying the temperature at which the pressure means opcrates the switch and maintaining substantially constant the periodic closing temperature of the switch.

4. In a refrigerator control, a switch, a pressure operated bellows for operating the switch, a resistance device for normally resisting the switch closing movement of the bellows, a second resistance device, means for periodically connecting the second resistance device to further resist the switch closing movement of the bellows, and means for adjusting the said resistance devices to produce the same proportionate change in opposite degree in each of the said resistance devices.

5. In a refrigerator, a swi ch, a pressure operated bellows for operating the switch, a ratchet wheel, means including a spring for yieldingly supporting the ratchet wheel for rotatable movements and movements transverse to the axis of rotation of the wheel, a pawl connected to the switch for rotating the ratchet wheel, the ratchet wheel having a part engaged by the switch at a point in its rotation for resisting closing movements of the switch by the bellows.

6. In a refrigerator control a compressor motor, a switch for controlling the circuit of the compressor motor, a pressure operated bellows for operating the switch, a pivoted arm, a ratchet wheel rotatably supported on the arm, a spring for resisting the movement of the arm, a pawl connected to the switch for moving the ratchet wheel step by step by opening movements of the switch, the ratchet having a part engaged by the switch to produce movement of the arm that is resisted by the spring upon a closing movement of the switch.

7 In a refrigerator control, a compressor motor, a switch for controlling the circuit of the compressor motor, a pressure operated bellows, a spring for resisting the movements of the bellows, a pivoted arm, a spring for resisting the movement of the arm, a ratchet wheel rotatably supported on the arm, a pawl connected to the switch for moving the ratchet wheel step by step by opening movements of the switch, the ratchet wheel having a part engaged by the switch to produce 3 movement of the arm that is resisted by the second named'spring upon a switch closing movement of the bellows, and an adjustable member for increasing the effectiveness of one spring and decreasing the effectiveness of the other spring.

8. In a refrigerator control, a compressor motor, a means for automatically opening the circuit of the motor upon flow of an excess current through the motor and also at a predetermined low' refrigerator temperature,-

and means for closing the circuit at a predetermined high refrigerator temperature, and means periodically operated for preventing the operation of the last named means until the refrigerator is defrosted.

9. In a refrigerator control, a compressor motor, a means for automatically opening the circuit ofthe motor upon flow of an excess current through the motor and also at a predetermined low refrigerator temperature and means for closing the circuit at predetermined high refrigerator temperature, and means periodically operated for preventing the operation of the last named means until the refrigerator is defrosted and an adjustable member for varying the high tempera ture circuit closing means and maintaining the high limit of the refrigerator defrosting temperature substantially constant.

10. In a refrigerator cont-r01, a compressor motor, a manuall operated means for opening and closing t e circuit of the motor and having an automatic means for opening the circuit of the motor upon the flow of an excess-current and also at a predetermined low refrigerator temperature and a means for closing the circuit at a predetermined high refrigerator temperature to produce a plu rality of normal refrigerating cycles, and a periodically operated means for retaining the circuit open to raise the refrigerator temperature to a predetermined defrosting value and restoring the temperature to the said normal operating cycle.

11. In a refrigerator control, a compressor motor, means for controlling the compressor motor and comprising a switch means actuated by an excess current through the motor and predetermined low and high refrigerator temperatures, the control having means for raising the temperature to defrost the refrigerator and an adjustable means for varying the normal refrigerator temperature and for maintaining the periodic high defrosting temperature substantially constant.

12. In a refrigerator control, a compressor motor, a circuit control means for controlling the circuit of the motor, a pressure means for operating the circuit control means at predetermined points of pressure to maintain normally predetermined refrigerating temperature limits, means for periodically actuating the circuit control means for raising the higher temperature limit without affecting the lower temperature limit for defrosting the refrigerator, andmeansfor adjusting the I pressure means to alter. the normal prede termined temperature limits to other normal refrigerating temperature limits and maintaining substantially constant the higher periodic refrigerating temperature limit for defrosting the refrigerator. v

13. A refrigerating system, comprising in combination a cooling element normally maintained at desired refrigerating temperatures, means rendered operable automatically at intervals by the normal operation of the system to permit rise of the temperature of the cooling element to a defrosting temperature limit, and means for varying the refrigerating temperatures While maintaining the upper limit of defrosting temperature of the cooling element constant regardless of variation of the normal refrigerating emperature.

14. A refrigerating system comprising means for starting and stopping a refrigerator at definitetemperature limits successive= ly for a predetermined number of cycles, an automatic means for increasing the starting temperature to a defrosting temperature for a defrosting cycle after the said precletermined number of cycles, means whereby the temperature range of the said successive 5 cycles ma, be readily adjusted without changing t e upper temperature limit of the defrosting cycle.

15. In a refrigerator, a switch, a pressure operated bellows for operating the switch, a ratchet wheel, means including a spring for yieldingly supporting the ratchetwheel for rotatable movements and movements transverse to the axis of rotation of the wheel, the

spring operating to resist the transverse movements of the ratchet wheel, a pawl connected to the sw ch for rotating the ratchet wheel, the ratchet wheel having a part en gaged by theswitch at a point in its rotation to move the ratchet wheel transverse to the axis of rotation of the ratchet wheel, the spring operating to resist closing movements of the switch by the bellows.

, 16. In a refrigerating apparatus, means for producing a plurality of cycles of operation,

at a predetermined temperature below 32 Fahrenheit the said means operating a predetermined number of times to close and open the circuit and means for closing the circuit during a single operation at a temperature in excess of 32 Fahrenheit and means for vary ing the opening and closing temperatures below 32 Fahrenheit Without changing materially the circuit closing temperature above 32 Fahrenheit.

In witness whereof I have hereunto signed my name to this specification.

' ESTEL G. RANEY.

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