US3350894A

US3350894A - Control device for refrigeration system

Info

Publication number: US3350894A
Application number: US373762A
Authority: US
Inventors: Thorner Robert Henry
Original assignee: Individual
Current assignee: Individual
Priority date: 1964-06-09
Filing date: 1964-06-09
Publication date: 1967-11-07
Anticipated expiration: 1984-11-07

Description

Q Nov. 7, 1967 R. H. THORNER CONTROL DEVICE FOR REFRIGERATION SYSTEM Filed June 9, 1964 4 Sheets-Sheet l l B cf/n e/v zfor h. QNQ

1967 R. H. I'HORNER 3,350,894

CONTROL DEVICE FOR REFRIGERATION SYSTEM Filed June 9, 1964 4 She ets-Sheet 2 0 1 60 Zfor Foals/en?! E am 0P 1967 R. H. THORNER CONTROL DEVICE FOR REFRIGERATION SYSTEM 4 Sheets-Sheet 3 Filed June 9, 1964 7, 1967v R. H. THORNER 3,350,894

CONTROL DEVICE FOR REFRIGERATION SYSTEM Filed June 9, 1964 4 Sheets-Sheet 4 (Zn 6060f 05597 77/0AW5/P United States Patent Office 3,350,894 Patented Nov. 7, 1967 3,350,84 CONTROL DEVICE FOR REFRIGERATION SYSTEM Robert Henry Thorner, 8750 W. Chicago Blvd, Oflice F, Detroit, Mich. 48204 Filed June 9, 1964, S91. No. 373,762 44 Claims. (Cl. 62-140) This application is a continuation-in-part of Ser. No. 342,216, filed Feb. 3, 1964, entitled, Control Device for Refrigeration Apparatus, which is a continuation of Ser. No. 43,825, filed July 19, 1960, now abandoned, and a continuation-impart of my co-pending application Ser. No. 100,137, filed Apr. 3, 1961, now abandoned, for Control Device for Refrigeration Apparatus.

The present invention relates primarily to a control mechanism for refrigeration apparatus and particularly to a control device for regulating the formation and reduction of ice on a cooling unit, such as for defrosting systerns of refrigerator apparatus. In a broader aspect, the present invention may be employed to control the thickness of formation of any substantially solid material (particularly if it is freezable and meltable) on or in any solid base, such as on a tube, rod, etc, or in a vessel, by any method or means such as by condensation, electrolytic process, etc.

In numerous refrigerating systems, means are provided to control the build-up and elimination (or reduction) of ice or frost which may form on the evaporator. These systems often include heating means to remove or reduce such formation of ice. In certain types of commercial refrigeration such as ice-bank systems, as well as in some defrosting systems, such removal means comprises merely a switch to turn the compressor off so that the ambient heat eventually diminishes the ice coating on the evaporator. For purposes of this disclosure, ice and frost can be considered synonymously, except where otherwise indicated.

Defrosting control systems are used to remove the frost that forms on the usual evaporator coils as well as on other parts or on food adjacent thereto in a refrigerator. Such frost is highly undesirable since it acts as an insulator for the normal extraction of heat from the food compartments to the cooling unit, thereby reducing the efiiciency thereof. Accordingly it is desirable to remove the frost quickly without melting the food, ice cubes, etc. Hence it has been common practice to provide additional means to intermittently apply heat to the evaporator and adjacent parts for periodically removing such frost rapidly and automatically. One such defrosting means comprises a separate electric heater element adjacent the evaporator coil; another defrosting means comprises a solenoidoperated valve which acts to pass the compressed refrigerant (such as freon) directly from the compressor to the evaporator while bypassing the condenser and capillary tube of the refrigerant circuit. The present invention is concerned, in the forms shown, with the means to control the thickness of formation of ice or frost on the surface of any of the refrigeration systems above referred to. The present invention is more specifically concerned, by way of example, with control means for initiating and terminating the intermittent action of the defrosting means of a refrigeration system.

The presently known defroster control devices provide either manual or automatic means to initiate the defrosting action. The manual means usually includes a push button so that initiation depends upon human decision. The presently used automatic initiating means frequently comprises a conventional clock mechanism to start the defrosting action after a definite time interval, such as twentyfour hours, or after a predetermined total running time of the compressor, such as twelve hours, for example. All present defroster control devices provide automatic means to control the duration (or termination) of the defrosting action. Such terminating means usually comprises a gas-filled bellows-type thermostat to shut off the defroster action when the temperature in the controlled food compartment rises to a predetermined value. However, sometimes clock mechanisms are also used to con trol duration.

A novel means for terminating the defrosting action which senses ice formation is disclosed in the above-referred to patent applications, and part of the present invention relates to improvements in the invention therein claimed.

Defroster control devices in recent years have become widely used in domestic refrigerators having a food freezer section that is separate from the so-called refrigerator or fresh-food section. The freezer section in such refrigerators is provided with a fan to circulate air over the evaporator coil and the frozen food products. With this construction and with intermittent defrosting of the freezer evaporator, frost never forms on the food, and the melted frost from the evaporator coil is disposed of automatically.

It has always been important to terminate the defrosting action as soon as all of the frost melts in order to prevent unnecessary heating of the food compartments and possible melting of frozen foods therein. However, the initiation of the defrosting action has not been too critical in refrigerators that lower the temperature only slightly below freezing, such as to 25-28 F., as in the fresh food compartment. But when defrosting the freezer sections of refrigerators having two food compartments, control of initiation is somewhat more critical. This is true since near-zero degree temperatures are maintained in the freezer section to assure quick freezing of foods placed therein, and to assure that the desired freezing is not hampered by insulation produced by excessive formation of frost. This problem is compounded because of the loss in efiiciency caused by transferring heat twice; the heat first is transferred from the food to the circulating air, and secondly from this air to the evaporator.

Preferably the initiation and termination of a defrosting cycle, if correct, should not be a function of time alone at least with present termination means responsive only to temperature. But the worst problems with present clock or timer mechanisms is their complexity and high cost, and they tend to become sufficiently noisy to require replacement because of wear in their fast-running gears. The use of clock means to initiate the defrosting action is acceptable if the cost can be reduced and the fore going objections are overcome. A time-initiated defroster control is rendered acceptable particularly if the mechanism controlling the termination of the defrost period actually controls the duration of the heating action irrespective of the original thickness of frost on the evaporator unit.

For termination of the defrosting cycle, gas filled bellows which sense only temperature are not only costly, but the gas therein is adversely affected by variations in air density. Accordingly, altitude or air density compensation means frequency are rovided to compensate for the low atmospheric pressures, such as those norm-ally existing at Denver, Colorado, for example. Also, the production consistency of present bimetal snap-disc temperature-termination systems cannot be held closer than plus or minus 5 degrees F.

It should be appreciated, of course, that the melting of frost or frozen food is not only a function of temperature of the surrounding materials but a function of time as well. Frozen foods or frost will melt in a short time at high ambient temperature, but can withstand ambient temperatures of a few degrees above freezing for a relatively long time without deterioration.

In those applications in which a controlled freezable material is fragile or friable (such as frost), the past attempts to mechanically sense the thickness of such friable material (frost) have required that the sensing member applies a force against the material which tends to crush or deform the surface thereof; this action, in turn, tends to produce inaccurate or inconsistent results.

Secondly, in some of the past attempts to mechanically sense the thickness or amount of material forming on a base, as above discussed, the control means (which usually includes means such as an electric switch) is moved gradually as a function of the formation of the material. In this instance, the operation of the electric switch is critical since the snap action must be set carefully to correspond exactly to the correct thickness of material.

A broad object of the present invention is to provide a simple and novel mechanism to control the amount or thickness of formation of any substantially firm or solid material on (or in) any solid base, regardless if accomplished by freezing or other equivalent means, as by electrical deposit.

Another object of the present invention is to provide a mechanism to control the amount or thickness of formation of any meltable material on a surface or base as described in the preceding paragraph, in which a periodically movable member is provided to sense the material formation with a force that will not deform the material to produce erratic measurement thereof, which sensing force :monitors a separate and larger force to actuate the control means in a servo-mechanism action.

A further object of the present invention is to provide a mechanism to control the amount or thickness of formation of any material on a surface or base, as described in either of the preceding two paragraphs, in which the control means is operated only after the material forms to substantially the desired predetermined amount or thickness.

A most important object of the present invention is to provide a mechanism to control the formation of any material on a surface or base as described in any of the preceding paragraphs in which means are provided to produce -a relatively small amount of energy, and integrating means are provided to store the energy over a period of time to be released periodically for providing the relatively large amplified force for actuating the control means.

Another object of the present invention is to provide a mechanism to control the amount or thickness of any material on (or in) a surface or base as described in the preceding paragraph in which a heat-sensitive clock or timing mechanism provides the input energy for the integrating mechanism that includes counting means to enable initiation of the defrosting action after a predetermined number of time intervals, which heat sensitive clock mechanism particularly in combination with the integrating mechanism has other applications in addition to controlling the formation of a freezable material.

A further object of the present invention is to provide a mechanism to control the amount or thickness of any material on a surface or base as described in either of the preceding two paragraphs in which the means to provide the small energy for the integrating mechanism includes novel heat sensitive means operating intermittently to provide the input energy.

A further object of the present invention is to provide in an automatic defroster control system novel means to control the duration (and termination) of the defrosting action including a sensing member immersed in a vessel in the flow path of melted frost and including improved means to initiate the defrosting action when first starting the refrigerator after installation and before the ice-containing vessel is filled with water.

A very important object of the present invention is to provide an extremely simple, reliable, small, quiet and low-cost defroster control providing novel heat-responsive clock means to cause initiation of the fIOS't-H'lfiltiflg action solely after a predetermined time interval, particularly in combination with a novel ice-abutment means for controlling accurately the duration of the defrost heating period irrespective of the initial thickness of frost formed on the evaporator unit.

Other objects and advantages of the invention will be come apparent from the following description and from the accompanying drawings, in which:

FIG. 1 is a somewhat diagrammatic illustration of a refrigerator having a freezer section with the device of the present invention shown in its operative relation to the several components of the refrigerator;

FIG. 2 is an enlarged elevational view of the control device of the present invention (with its cover removed) for controlling the duration of the defrosting action by controlling the initiation and termination thereof;

FIG. 2a is a modification of the form of the invention shown in FIG. 2;

FIG. 3 is an isometric view of an important element of the device shown in FIG. 2, to clarify its operation;

FIG. 4 is an elevational view of the device of FIG. 2 as would be seen along the line 44 of FIG. 2;

FIG. 5 is an elevational view of the device of FIG. 2 as would be seen along the line 55 of FIG. 2;

FIG. 6 is a fragmentary elevational view of the integrating portion of the device of the present invention exactly as shown in FIG. 2, but substantially four-times actual size to enable clearer understanding of the device;

FIG. 7 is a modified form of the invention disclosed in FIG. 2; and

FIG. 8 is an elevational view of the device of FIG. 7 as would be seen along the line 88 of FIG. 7.

It is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

In a broader aspect of the inventive concept, I provide a control device to effect a change in condition, such as bulk or thickness of any firm or solid material, such as frost for example, capable of being deposited or frozen on any surface. I provide control means for regulating the change, such as a switch in an electric circuit, and actuating means norm-ally movable independently of the control means and disposed to operate same periodically. I provide sensing means mounted at a predetermined relationship with respect to the material and movable in relation thereto (intermittently) in response to the periodic movements of the actuating means. The sensing means is operated by a very low force and is disposed to preclude the actuating means from operating the control means with a relatively large force whenever the intermittent movements of the sensing means is not blocked or prevented by the bulk or mass of the material; but

whenever the intermittent movements of the sensing means is blocked or prevented by the bulk of the material, the actuating means can then operate the control means. In this manner, the control device provides an action similar to that of any servomechanism.

In addition, because of this servo-action, the foregoing combination may be arranged for those applications in which the material is friable or fragile (such as frost), to provide that the force of the movable sensing element acting on the friable material is substantially less than the force of the actuating means for operating the control means; so that the force of the sensing means does not crush or deform the material to cause inaccurate or inconsistent results.

In accordance with one specific form of the invention shown herein, I provide an automatic defroster control for a refrigeration machine in which the detrimental factors of present controls such as high cost, complexity, excessive noise, unreliability, inconsistency, and variations with air density are eliminated, and which will initate the defrostng action after a predetermined thickness of frost is formed, and will melt substantially all the frost (without melting the frozen foods). I provide such desirable initiating action by a mechanical construction in which an actuating member is intermittently operated by power means activated by a source of energy and disposed for occasional engagement and activation of the terminating means. A sensing element is provided to move toward the cooling unit or other ice-holding surface in response to each of the initial movements of the power-operated member when insufficient ice exists on the evaporator. The sensing element includes means upon such intermittent movements thereof to preclude the power-operated member from engaging and activating the terminating means when insufiicient frost or ice has formed on the cooling unit, but to enable engagement with and activation of the terminating means whenever the ice or frost has formed to a predetermined thickness to block the movement of the sensing element. Since frost is fragile and pliable, only a very light force can be applied thereon by the sensing element to measure the frost thickness with acceptable consistency and accuracy. The force and travel of the sensing element in my invention can be very small compared to the force and travel of the actuating member; and this small sensing force and travel controls the larger separate force and travel.

The power means, in the form shown, is operated by a relatively small source of such energy or input power force to operate an integrating mechanism- (which may be part of the power means) for storing or adding up this small energy over a period of time and for releasing the stored energy periodically at an output force substantially larger than the original input power force. Although any means for controlling the termination or duration of the defrosting cycle may be used and operated by the above-described initiating means, I have disclosed herein a novel means dependent on the melting of ice (preferably contained in a vessel) located in the flow path of melting frost to control this duration; this novel termination means has special utility when used in combination with my novel cycle-initiating means.

In another very important specific form of the invention, I provide by omitting the thickness-sensing elements a unique combination in which the above-described power means operates as a thermal clock mechanism to operate the novel mechanism for controlling the duration of the defrosting period. This combination has been found to enable startling simplicity in actual product design which enables low-cost, reliable, compact and noiseless operation.

Referring now to the drawings, and particularly FIG. 1, there is shown diagrammatically by way of example an installation of the present invention as a defroster control unit in operative relation to a refrigeration machine and the electric circuits necessary for operation of the control unit. The entire defroster control is shown in FIGS. 2-6 encased in a housing 11, and includes a pair of legs or supports 12 and 13 adapted to be secured to the refrigerator at any suitable position on the frostforming surface. The defroster control may be considered to comprise two components; one component comprises an initiating mechanism or means 14; and the second component comprises a termination mechanism 15 which con trols the duration (or termination) of the defrosting action as shown in FIG. 2. In FIG. 1, a typical refrigerator is illustrated having a cabinet (in dotted outline) forming a food freezer section 19 and a fresh food section 21 divided by walls 23 and 25. The refrigerant system includes the usual compressor C which sends the refrigerant through a tube 27 to a condenser D, thence through a capillary tube 29, to be expanded through a frozen food evaporator or cooling unit 30 of the usual tube coil construction, where it either returns under vacuum to the compressor through tube 31 or flows to a second evapora tor 30a (shown dotted) for the fresh food section 21, all in a manner well known to those skilled in the art. A conventional solenoid-controlled valve S is mounted in a tube 32 which may bypass refrigerant around the condenser directly from the compressor to the evaporator coil 39. When the solenoid valve is opened, by action of the defroster control It to be described, the hot refrigerant passes directly from the compressor through the evaporator which quickly melts all the frost formed thereon. The melted frost drops into a trough 34 mounted at the back of the freezer section where the water flows through a tube 36 to a pan 38, where the heat of the condenser helps the melted frost to evaporate. In normal operation, the contents of the freezer section are cooled by air circulated by a smal lair fan P which causes air to circulate around the freezer section and over the evaporator 3t} and frozen food. The defroster control is secured to tube 30 by any suitable means, as by clamps and screws on legs 12 and 13 as illustrated.

Temporarily referring to FIG. 2, to be discussed in detail hereinafter, the termination mechanism 15 includes an electric switch having a fixed contact 39 connected to a terminal 40, and an opposed fixed contact 42 connected to a terminal 44. A movable contact 46- is carried by an arm 48 swingable about a knife edge connection in a support 50 which is connected to a stationary terminal 52. A strong extension spring 53 is connected at one end to the contact arm 48 and at its other end to an arm 54 which has knife-edge connection with support 50. The switch is shown in its normal position without the defrosting sys tem in operation, and in this position terminal 52 is electrically connected to terminal 40 through contact 46 resting on contact 39 by the force of spring 53. When arm 54 is moved to the left, as viewed in FIG. 2, by means to be described, spring 53 is moved over center to the right, as viewed in FIG. 2, so that contact 46 snaps against contact 42 to electrically disconnect terminal 52 from terminal 40 and connect to terminal 44. In this position, however, the spring 53 maintains a relatively large force urging the arm 54 back to the original position shown in the drawings since the position of the spring is always at the left of the fulcrum of the arm 54. When arm 54 is moved back to its original position shown, the contact 46 is also snapped back to its original position shown in FIG. 2. Another terminal 55 is provided for reasons to be discussed hereinafter.

Again referring to FIG. 1, line voltage is directed through a wire or conductor 56 to a two-pole thermostat switch 58 for the freezer section which energizes compressor C when the temperature at a bulb 60 rises to a predetermined value. Line voltage from wire 56 also is taken to terminal 52 of the defroster control. Another conductor 62 may optionally be provided to connect the normally-closed pole of switch 58 to terminal 44 (FIG. 2). Also the solenoid valve S is connected to terminal 44 by Wire 64 in parallel with the compressor when the circuit 4 to the latter is closed only through the switch in the defroster control unit.

The action of the refrigerator and defroster control is as follows. When thermostat switch 58 closes the left pole as viewed in FIG. 1, with the defroster control switch in the position shown in FIG. 2, the compressor lowers the freezer temperature in a normal manner until shut ofi by the thermostat. However, when the defroster control causes arm 54 to move to the left in a manner to be described, the compressor C is operated regardless of the position of switch 58, and solenoid valve S opens the bypass line 32 to pass hot gas through the evaporator 39 until all the frost melts and is collected in pan 38 as described. At this time the fan F is turned off since contact 46 leaves Contact 39. After all the frost is melted, the defroster control causes arm 54 and contact 26 to return to the position shown in FIG. 2, by means to be de scribed, which restores normal refrigeration and starts fan F. Conductor 62 may be omitted if desired since the thermostat closes its switch shortly after the defroster control switch opens solenoid valve S to shut off the refrigeration. However, with wire 62, the heating starts sooner.

It should be appreciated that there are many possible combinations of refrigerator arrangements and circuits. For example a refrigerator may have one or two separately closed compartments; in a two compartment unit, the freezer section may be on top or below; or the defrosting system may utilize hot gas or electrical resistance unit-s, etc. Also, the defroster control 10 might be mounted in many different portions of the refrigerator, such as at the back of the freezer section between the inner or outer liner, or mounted inside the freezer compartment directly on the coil 30 as illustrated. Also, the evaporator coils are frequently mounted horizontally as well as vertically; my defroster control is adapted to operate in either vertical or horizontal positions. In addition, the ice-thickness or defroster control device can be used for any kind of refrigerating machine, not just as a defroster control for the freezer section of a domestic refrigerator as described in connection with the principal form of the invention. Hence, the particular combination shown in FIG. 1 is merely illustrative, for controlling the frost in the freezer section 19 shown in the lower portion of a two-compartment domestic refrigerator.

Now referring to FIGS. 24, the means to control the termination of the defrosting action will first be explained. In the component 15, the mechanism is encased in the housing 11 of any suitable material such as molded plastic. A wall of the housing is formed by the electrical insulat ing base 69 for the switch, which base is inserted in slots molded in the housing and retained by the housing cover 11a in FIG. 5 but shown removed in FIGS. 2 and 6. In component 15, the arm 54 carries a detent member 72 hinged thereto by a knife-edge 73 at one end to permit angular movements of the detent in relation to arm 54. A link 75 has one end thereof inserted in a cavity of detent 72 to provide another knife-edge connection 72a in relation to detent 72. The other extremity of link 75 is positioned by a supporting arm 76, to be discussed further herein. A light extension spring 74 is suitably secured at one end to the housing 11 and at its other end to a portion of link 75 urging the detent 72 downwardly into engagement with a cam or guide member 77. Although the cam 77 is illustrated as part of the plastic housing, it may be separate and secured by any suitable means to enable adjustment for production units as shown in my Patent No. 2,949,016.

A shaft 80, which may be a molded portion of the plastic housing 11, is provided to support a latch member or arm 82 for angular movements with respect to the shaft. A very light expansion U-spring 84 is suitably secured at one end to housing 11 and at its other end to a sensingportion or arm 85 of latch member 82 to urge same in a counterclockwise direction into the free position shown in FIG. 2 into abutment with a stop 86, which may be part of the plastic housing 11. Detent 72 includes a catch portion 88 disposed to engage latch member 82 in a manner to be described.

A small vessel 96, as shown in FIGS. 2 and 5, is suitably sec-ured to a portion of the evaporator tube 30 such that the vessel is below the tubing. The vessel may be made of any suitable material, but a metal such as aluminum is desirable to provide heat conductivity. The vessel is mounted so that the sensing portion 85 of arm 82 is suspended to extend an end thereof inside an ice chamber 98 formed by the vessel. A semi-cylindrical starter member 100 may be loosely secured to arm 85, as by a pin or rivet to slide against the surface of tube 30 in operative movements of arm 85 for reasons to be discussed. The starter member is loosely secured to sensing arm 85 so that starter 100 is self-aligning to lay smoothly against tube 30 regardless of production variations.

The operation of the termination mechanism above described is as follows. Referring to FIGS. 14, assume that chamber 98 of vessel 96 is completely filled with water or other freezable liquid which is frozen in normal refrigerator operation. After frost forms on the evaporator to a predetermined thickness, the link is automatically moved temporarily to the left by means to be described until arm 54 is moved to its extreme leftward position as viewed in FIG. 2. This action causes contact 46 to move against contact 42 which operates the compressor and solenoid valve to send hot gas through evaporator 30 for melting and disposing of the frost in a manner previously described. At this time the ice or frozen liquid in vessel 96 is also subjected to heat somewhat by radiation but primarily by conduction from the tube 30. Also, movement of the switch arm to its leftward position carries detent 72 leftward until spring 74 causes catch portion 88 to engage latch arm 82. The leftward force on link 75 is soon removed, as will be described. Then the force of spring 53 tends to return arm 54 into the position shown with a force that easily overpowers the force of spring 84. Such forces are transmitted through detent 72 which now abuts latch arm 82 tending to impart clockwise angular movement thereto. However, such angular movements are prevented by the sensing arm portion 85 now abutting against the ice or frozen liquid in vessel 96 which tends to be compressed between the left edge of the sensing portion 85 and the left inside wall 96a of the vessel. Thus, the ice acts as an ice or frozen-liquid link which grows smaller gradually as the ice or frozon-liquid progressively melts since contact with the melting ice is maintained by spring 53. As arm 54 with its detent member 72 gradually moves rightwardly as the ice in vessel 96 melts, the end of the detent member contacts cam 77 which gradually raises the detent member in opposition to spring 74. After a predetermined travel of arm 54 and detent 72 which is calibrated to occur when all the frost is melted, the catch portion 88 disengages from latch arm 82. This instantly causes two simultaneous actions as follows: The first action is that spring 84 instantly returns latch member 82 counterclockwise into the angular position shown in FIG. 2 in which the latch member abuts the stop 86; accordingly the sensing arm 85 is moved rightwardly away from the remaining ice and restored to its original position shown. The second simultaneous action is that the high force of spring 53 causes arm 54 and detent 72 to snap into the positions shown in FIG. 2, which also moves the contact 46 into the position shown against contact 39. This terminating action causes the solenoid valve S to shut off the flow of hot gas through the bypass tube 32 so that refrigerator operation is again normal. The compressor is again controlled only by thermostat 5S, and the ice in the vessel 96 soon freezes so that the defrosting cycle can be repeated as above described after a predetermined thickness of frost is formed.

It is important to appreciate that all the ice in vessel 96 may not melt, but only that portion adjacent the metal surfaces such as at sensor portion 85 and the interior walls of vessel 96. The component is so calibrated that when all the frost on the evaporator is melted, the detent member 72 is disengaged from latch arm 82 after a predetermined travel. This can be controlled by numerous variables such as the height of water in chamber 98, the thickness of metal of the sensing portion 85, or the heat conductivity of all adjacent materials, for example.

It is important to appreciate that the detent travel is always larger than (and easily includes) the travel necessary to cause contact point 46 to snap between contacts 39 and 42. Hence the production setting of the switch snap is not in the least critical, as in many prior devices; because for production units it is only necessary to provide the relatively large travel of deten-t 72.

When the refrigerator is first placed in service and water is to be the liquid in the vessel, the present invention provides improved means to preclude the necessity of filling chamber 98 wtih water initially to make the defrosting system operative. The construction also produces a more accurate calibration since the device is arranged to sense at least partially the accumulation of frost directly. As explained above, an abutting frost sensor such as starter 100, contacts tube 30 in all positions of sensing arm 85. Also, vessel 96 is mounted below tube 30 to be in the flow path of melting frost to keep chamber 98 completely filled, whereas the overflow falls into trough 34 to be evaporated as described. As explained above, the control is calibrated to terminate the defrosting action after a predetermined melting time dependent on numerous factors including a completely full amount of water in vessel 96. Thus, as calibrated, if chamber 98 is only one-half full, the defrosting action would terminate before all the frost is melted.

The defrosting action is developed as follows, starting with a completely empty vessel at the time the refrigerator is first placed in service. When the frost forms to its predetermined thickness on tube 30, a portion of the frost covers the frost sensor or starter 100. Then after link 75 is moved to start the first defrost heating action, arm 85 is moved gradually to the left by spring 53 and catch portion 88 as the frost which is abutted by starter 100 melts until detent 72 disengages from latch arm 82. The frost tends to be compressed between the starter 100 and leg 12 which is part of housing 11. In other words, the starter member actually abuts the frost trapped between the starter and the adjacent surface of leg 12. However, without water in the vessel (as calibrated), only a small portion of the frost melts on this first cycle but some of this melted frost falls into chamber 98 to cover perhaps only the tip of sensor portion 85. Then the second defrosting cycle will be longer due to the small amount of ice added in vessel 96, so that a larger percentage of the frost is melted during this second cycle. Some of the additional melted frost again falls in chamber 98, so that a higher percentage of frost is melted on each subsequent defrosting cycle. This action continues until the vessel 96 is completely full so that all the frost is melted during each subsequent cycle as calibrated. In actual operation, the vessel is full after only the first few cycles when the refrigerator is first placed in service. The calibration is partly produced by the arm 85 or starter member 100 compressing or abutting the frost between it and the leg 12 and partly by the sensing portion 85 compressing or abutting ice between it and the wall 96a of the collecting vessel.

Since a very small amount of frost accumulates on the first cycle, the large surface area of the frost sensor or starter 100 provides a bond to maintain the defrosting action for a suitable first period. Also, the starter member 100 is relatively thick, as shown in FIG. 5, to provide ample end area for compressing whatever frost that forms between the starter and the right side of the leg 12. This novel construction enables the foregoing process to function as desired.

Tests of this concept have shown that the defroster control can be calibrated satisfactorily to terminate the defrosting action without vessel 96 by using only the direct frost sensor starter 100 or equivalent abutting means as a sensing member to entrap frost between the sensor and the leg 12 or equivalent stop or abutment means. However, in this instance the control device must be mounted on the evaporator coil 30 somewhat near the last portion of frost to melt. When the vessel 96 is combined with the abutting frost-sensor 100, although the cost increases slightly, the control unit can be mounted anywhere on the evaporator coil since the travel of sensor arm 85 can be calibrated to terminate the defrosting action at a position corresponding to the last portion of frost to melt, even if remote from the control device.

The principle of the duration control unit 15 as above described, except for the automatic vessel-filling means shown in FIG. 4, is disclosed in my Patent No. 2,949,016, in which the theoretical concepts are discussed in more detail. It is important to appreciate that any duration (termination) control device may be used or operated by the novel initiating control means now to be described. However, the inherent simplicity, reliability, consistency, function accuracy, and potentially low cost of the duration control disclosed herein provides an inventive combination with the initiating means now to be described.

Now consider the means 17 to initiate operation of the duration control device, which in the specific duration device disclosed herein, comprises the means to eifect periodic or occasional intermittent movements of the link 75 after a predetermined amount of frost has formed. Referring to FIGS. 2 and 6, the link 75 is disposed to be actuated occasionally by an actuator or power output member 104 supported by a pair of

shafts

106 and 108 projecting through slots 110 and 112 respectively, in actuator 104. The shafts are suitably secured to (or are a part of) the housing 11 in a cavity 14a in which most of the initiating mechanism 14 is housed. A sensing memher 116, which is made of any suitable material such as metal or plastic strip, is guided in a slot 118 by molded portions 119 of the plastic housing 11 to provide sliding movements in a direction transverse to the direction of movement of the actuator 104. The sensing member, as illustrated in FIGS. 2 and 6 is positioned to completely clear the link 75 and actuator 104 in its transverse movements.

The sensing member includes a slot 120 through which is projected a cam portion 122 of actuator 104. The sensing member is held against the cam portion 122 at the upper end 120a of the slot 120 by the force of spring 74, assisted by gravity in vertically mounted installations. The spring 74 applies a downward force on the link 75 to be transmitted through arm 76 to a knife-edge support 116a which is part of the sensing member 116. Arm 76 includes knife-edge connections at each end, respectively, with link 75 and support 116a to provide low cost frictionless movements of these elements. The sensing member 116 includes a frost sensor 1160 disposed at an angle to the tube 30 to contact the frost for measuring its thickness by periodic movements toward and away from the tube 30.

With the foregoing construction, as viewed in FIGS. 2 and 6, a leftward movement of actuator 104 (by means to be discussed) enables the sensing member 116 to move downwardly toward the evaporator tube 30 under the influence of spring 74 (and/or by gravity) as permitted by cam portion 122. When the actuator is returned to the position shown by a spring 124, the downward force of spring 74 is overpowered so that the sensing member 116 and its sensor 1160 is raised to the original position shown in FIG. 2. The sensor 1160 is normally maintained at a predetermined distance from the coil 30', which distance generally will correspond to the maximum frost thickness, as will be discussed further. The actuator is periodically moved to the left and returned by means to be discussed, so that the frost sensor moves correspondingly in response to such actuator :movements to feel the formation of frost.

The link 75 includes a stop or tab 75a which, in the off position shown in FIG. 2, is in the path of travel of a catch 104a included in actuator 104. With insufiicient frost on tube 30 (FIG. 2), when the actuator periodically moves to the left, the

elements

116a, 76 and 75 all are moved downwardly to carry the stop 75a clear of the path of travel of the catch 104a. Hence, in this condition, the sensor 116c detects insufiicient frost on the tube so that the actuator misses and passes by the link 75 and its stop 75a, so that the switch arm 54 is not disturbed and the control means is not operated. However, after the frost builds up on tube 30 to the maximum permissible thickness, the sensing member 116 is blocked for downward movements by the frost. Then the next periodic operation of actuator 104 causes the catch 104a to abut the stop 75a and move the link '75, detent 72 and switch arm 54 to the left, as viewed in FIG. 2, to operate the switch and initiate the defrost heating action in a manner previously described. Now the terminating mechanism 15 controls the duration of the frost heating means; then after all the frost melts and the defrosting cycle is terminated, the entire defroster control is ready for the next cycle.

Thus, if insufficient frost exists on tube 30, the periodic movements of actuator 104 causes corresponding movements of the sensing member 116 and stop 75a down and clear of catch 104a to preclude actuation of link 75, so that the defrosting action is not initiated. But when the frost has formed to the maximum desired thickness, this downward movement of the sensing member is prevented by the frost, so that the actuator abuts the link 75 to operate the switch and initiate the defrost heating action. In his manner, the sensor 116c is caused to move occasionally toward and away from tube 30 to feel or sense the frost upon each intermittent operation of the actuator 104; and defrosting is initiated only after the frost has formed to a predetermined amount determined by the distance of sensor 1160 from tube 30 in the position shown in FIG. 2. The sensor 1160 is at an angle to carry melted frost clear of the frost forming surface of tube 30.

The downward force of spring 74 acting on sensor 1160 is very light compared to the relatively large force required to operate the switch by moving arm 54. This large actuating force is provided by the actuator 104 in a mannet to be described. The control of whether this large force and travel acts on or misses the control means is determined by the relatively small force (and travel) of the sensing member 116. In this concept, the action is similar to any electric or fluid servomechanism in which a small sensing force and travel controls a larger and separate force and travel acting as a slave or muscle. In other words, signal at a small energy level is amplified and accurately reproduced at a much higher energy level by a separate and greater source of energy or force.

Referring to FIG. 1, if an electric heater is provided to melt the frost instead of the hot-gas bypass tube 32 and valve S, the wire 102 would then be connected to terminal 40 (FIG. 2). With this arrangement, the compressor would be turned off when the defroster cycle starts. Now consider the portion of the initiating mechanism 14 which provides this relatively large actuating force by actuator 104. This force is produced by a forceamplifying mechanism interposed between the actuator 104 and a force-input power means or element, and is disposed to reduce substantially the force and energy required of the force-input power means as well as reducing its size and travel. Broadly this reduction in the size of the input power element and the energy required therefor is to provide such a force-amplifying mechanism which integrates and stores the small energy over an extended period of time; and means are provided to release this stored energy at the end of this time period to provide a 12 substantially larger actuating force by actuator 104 than possible without the integrating mechanism. Also, the travel of the actuator 104 is much larger than the travel of the input means.

The force-amplifying mechanism illustrated in FIGS. 26 will now be explained. A charging gear is rotated slowly, such as once per three hours for example, by a ratchet wheel 126 having ratchet teeth 127 supported by and rotating on the shaft 106. The ratchet wheel includes a gear portion 128 having teeth :meshing with gear 125 for rotating same at a speed reduction and torque increase in accordance with the size ratio of ratchet wheel 126 and gear portion 128. The ratchet wheel is revolved slowly on shaft 106 by the input power means to be described.

A pin 130 and a detent 132 are connected to and carried by gear 125. Detent 132 is prebent slightly so that hinge pin 134 applies friction force to maintain the detent in any set angular position. A pinion-piece 136 includes an arm 138 which rotates freely on shaft 108 separate from gear 125. A latch 140 is hinged to the housing 11 and includes an extended tab 142 disposed to engage pin 130 for actuation thereby. The actuator 104 is supported and guided by

shafts

106 and 108 for axial sliding movements as explained, which shafts are supported at one end thereof in the housing 11. The actuator 104 includes a catch 144 for engaging the latch 140. A powermember 146 includes a pair of pins 148 projecting through a corresponding pair of slots 150 for supporting the power member and to provide relative movement between itself and actuator 104. A preloaded power spring 152 urges the actuator 104 and power member 146 together against a tab 154 of the actuator, and the lighter return spring 124 urges the assembly to the right into the position shown. One end of return spring 124 is connected to tab 154 and the other end is connected to a tab 156 of latch 140' urging the latch to ride on top of the actuator. One end of spring 152 is connected to tab 154 and the other end is connected to a tab 158 of actuator 104. The detent 132 includes a tab 160 disposed to be abuttecl by a cam-portion 162 of the actuator 104. The teeth of pinion 136 engage the teeth provided in a rack-portion 164 of the power-member 146. The actuator includes another cam 122 to operate frost-sensor 1160, all as previously explained.

In operation, briefly, the gear reduction means amplifies torque and causes the power member 146 to creep leftwardly for slowly storing energy in power spring 152. This energy is released by latch 140 once every three to five hours, for example, for enabling actuator 104 to snap to the left for operating the defroster control mechanism as described above; and then the spring 124 returns the entire assembly to the position shown to repeat the cycle. More specifically, this action is accomplished as follows: Starting from the positions shown when gear 125 rotates slowly, the catch 132a of detent 132 engages arm 138 to rotate pinion 136 acting on rackportion 164 to move the power member 146 to the left. But at this time, the actuator 104 is held in fixed position by latch 140 so that spring 152 slowly is extended to store energy acting on the actuator. When gear 125 has revolved nearly one turn, the pin 130 abuts tab 142 to move latch 140 clear of catch 144. The stored energy of spring 152 now snaps actuator 104 to the left to operate the defroster sensing mechanism as required. Before the tab 154 strikes the housing, cam-portion 162 abuts tab 160 to move and set the detent 132 in a position clear of arm 138. Now the return-spring 124 moves the springabutted assembly of actuator and power-member to the right until they are restored to their positions shown after latch 140 again engage catch 144. However, since detent 132 is now positioned clear of arm 128, the pinionpiece and its arm was rotated rapidly one complete turn clockwise as a result of the power member being returned to the position shown by spring 124.

When the gear 125 rotates upon termination of a defrost cycle (refrigerator fan starts), the detent 132 does not actuate arm 138 so that no energy is stored in the spring during the first revolution of gear 125. When the detent 132 passes a cam 166, it is moved back to its position shown and held thereby friction. After the first revolution of gear 125 is completed, all parts are in the position shown. Then during the second revolution of gear 125, arm 138 is actuated to slowly store energy in the power spring, and the entire cycle is repeated as above described. Thus, in this example, if the first revolution (under no-load) requires 1% hours and the second revolution (under load) requires 3% hours, the actuator would fire once every 4% hours.

Means are provided to produce the small input power force or energy required to operate the foregoing mechanism. In the form of the invention illustrated in FIGS. 26, such input-power means comprises a heat-sensitive element which alternately is heated and cooled under control of a switch operated by the element itself to alternate the application of the heat energy. Referring to FIGS. 2, 4 and 6, the heating element illustrated therein comprises a bimetal leaf or strip cantilever element 168 suitably secured at one end to a support 170 of a base 172 attached to (or a part of) housing 11. An electricswitch contact 174 is carried by the bimetal to alternately engage a fixed contact 176. An electric heating element 178 is connected between

terminals

52 and 55 and includes

contacts

174 and 176. The heater element 178 is either wound around bimetal 168 or otherwise mounted adjacent thereto. A magnet 180 is loosely secured to the bimetal strip 168 to cause a snap-action between the legs of a soft iron U-bracket 182 suitably secured to base 172. A ratchet arm 184 is secured to bimetal strip 168 by suitable means, as by a rivet, and includes a portion to engage and move ratchet teeth 127. The arm 184 may comprise merely a bent portion of the bimetal strip if desired.

As the bimetal heats slowly to overpower the light force of magnet 180, it snaps upward to cause ratchet arm 184 to move ratchet wheel 126 clockwise one toothlength. Counter-clockwise rotation of ratchet wheel 126 is prevented by a pawl 186 secured to housing 11, as by rivets. After the bimetal cools enough with

contacts

174 and 176 now open, it overcomes the magnet force and snaps to the position shown to close the contacts, and the heating cycle is then repeated. The magnet 180 may be secured to bimetal 168 by means providing universal or floating movements to enable self-alignment with the legs of the U-bracket. Also, if desired since the current is so low, the contact 174 may be omitted if the magnet itself is disposed to comprise the electric contact. It is apparent that this portion of the integrating mechanism includes a mechanism to count the number of pulses of the power means.

Many combinations of ratchet teeth and gear reductions may be provided to produce a widely varying time cycle. For example, if the ratchet wheel has 50 teeth, with a 4 to 1 gear reduction and a 30 second bimetal heat cycle, and with two rotations of the charging gear 125, the actuator will fire about once every four hours. All or part of the interior of housing 11 may be insulated with a suitable heat resistant material to help establish any desired time cycle. If cam 13% is reduced, and cam 1320 is provided as dotted, the gear 125 will only revolve once between firings.

In the overall defroster control operation, if insuflicient frost exists on tube 30, at each firing of actuator 104 the catch 104a will miss the stop 75a to preclude actuation of link 75, so the defrost cycle is not started. At the first firing of actuator lMfollowing the buildup of frost to the maximum thickness, the catch 104a strikes stop 75a to initiate the defrosting action and the duration mechanism 15, all aspreviously described.

Novel means are disclosed to provide a heataesponsive Cir 14 clock mechanism for causing initiation of the frost-melting action solely after a predetermined time interval irrespective of the thickness of frost on the evaporator unit. Such means are disclosed herein in FIG. 2a, which is a modification of FIG. 2 in which the sensor 116a is omitted and the sensing member is replaced by a fixed support 117 suitably secured to the housing 11, as by a rivet. This modified construction illustrates how means can be provided to effect initiation of the defrosting mechanism each time the actuator 104 fires solely upon predetermined time inter-- vals independent of the amount of frost that forms on tube 30. Since the support 116a is now fixed, the stop a is abutted by the catch 104a each time the actuator 104 is operated. The

elements

116a, 117, 76, 75, 75a, 104 and 184a, in FIG. 2a comprise a lost-motion means, and any other equivalent lost-motion mechanism may be employed. In this modification, the integrating mechanism and its reciprocating power means, such as the bimetal and associated

elements

168, 178, 174 and 176 actually comprise a thermal clock or timer mechanism. The various constants are selected such that the actuator 104 will fire once about every 10 or 20 hours, for example, or as required by each manufacturer. These constants might comprise the gear 125, the wheel 127, the number of teeth of each, the size of the bimetal element 168, the size and type of heater wire 178, etc. The defroster control can be connected by means well known in the art either to operate on total refrigeration time or merely for the total or aggregate time of compressor operation. This form of my invention is simpler than in FIG. 2, and does not require calibration or installation considerations for frost thickness. While the bimetal clock means described above has utility, per se, actual tests have proven that the principle of the ice-abutment termination means disclosed herein is so accurate, that it actually controls the duration of the defrost heating period irrespective of the initial thickness of frost; also, this ice-abutment principle depends on the melting temperature and heat of fusion of ice which is absolutely consistent in all production units, the variation in production units is very small. Hence, these two important factors enable the practical utilization of the novel bimetal cloc mechanism as the sole initiating means whichis desirable because of its small size, inherent reliability, noise-free operation, low cost and inherent simplicity. Hence, the combination of the novel ice abutment termination (duration) mechanism with the bimetal clock mechanism disclosed herein has great utility. However, the form of the invention shown in FIG. 2, of course, is more accurate and presumably would be used in higher priced refrigerators. The term clock mechanism is used herein in the sense of a timing mechanism. Hence, whenever the term clock appears herein in the specification and claims, it is synonomous with timer or timing mechanism, so that these terms can be used interchangeably.

FIGS. 7 and 8 illustrate a modified form of the present invention. The operation of the form shown in FIG. 7 is the same as for FIGS. 2 and 6, so that only the modifications need be discussed. In FIG. 7, a snap-type bimetal element 188 replaces the straight bimetal element 168 and magnet 180 of FIG. 2. Since the bimetal itself produces the snap action, the magnet 180 is not required. Also, the ratchet wheel 126 is deleted and the ratchet teeth 127 are made a part of the charging gear 1'25, now comprising a charging ratchet wheel 125a. A bellcrank rotates on shaft 106 to transmit forces and movements of bimetal 188 to actuate the ratchet arm 184 acting on ratchet teeth 127, as in FIG. 2. With this construction, the bimetal 188 acts directly on the charging wheel 125a. Although this arrangement is somewhat simpler than the form shown in FIG. 2, it will not produce as large a force amplification with the extra gear 126 of FIG. 2. The operation is otherwise the same except the heat cycle of the: form of FIG. 7 preferably should be longer than that of FIG. 2. This may be aidedby providing a molded casing as part of housing 11, such as by a wall 11b.

Another modification disclosed in FIG. 7 is to connect the bimetal heater between

terminals

40 and 55. In this construction, the heater is turned off during the defrosting period, whereas it continues to cycle while defrosting as connected in FIG. 2. Also a safety shut-01f is disclosed in FIG. 7 to turn off the heater in the event of a failure of the switch to shut-off the defrosting action. A safety spring wire-member 192 is inserted in a slot 194 which is molded in housing 11. The spring 192 is held in a bent position to the right by a solid heat sensor block 1% which melts on heating (such as wax) and abuts a plastic projection 1% of the housing. If the switch or defroster fails to turn off the defrost heating means, after the temperature rises to about 150-200 degrees F the sensor block melts or softens which enables the spring 192 to strike switch arm 48 to shut-off the heater.

It is important to appreciate that in both forms of the present invention, the specific integrating or energy storing mechanism disclosed herein also comprises a novel heat clock, which determines the periods between movements of the sensor 116a to feel the formation of frost.

In both forms of the present invention, the defroster control is arranged to start with a small force and store it over a period of time for sudden release to provide the large force and travel needed to operate the switch. This amplified force and travel in the form shown in FIG. 2 is controlled by another and separate very light (sensing) force having a small travel, thereby providing the action of a servomechanism. This light sensing force does not tend to crush or deform the frost. In my device, since the forces operating the bimetal can be so low in relation to the capacity of the respective parts, they will give lifetime operation in production units. This is enabled by the integrating mechanism and enhanced by the servomechanism action.

What I claim is:

1. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material said mechanism including a source of energy supplied thereto in normal operation thereof, the combination of; control means for effecting a change in the quantity of said material forming on said surface, initiating means to periodically cause operation of said control means when said material has formed to an undesirable quantity on said surface, said intiating means including, power means having a movable element affected by said energy source to provide a small pulsating input power force, force-amplifying means operated by said input force of said power means to integrate and store said energy over a period of time for providing an amplified output force substantially larger than said input power force available to cause operation of said control means, and said amplifying integrating means including means to release said stored energy after said period of time to produce said amplified output force for operating said control means, said power means including energizing means mounted near said movable element and supplied by said source of energy for causing reciprocating movements of said movable element and simultaneously said pulsating input forces, means to regulate the amount of said energy to said energizing means and operated by said element to reduce said energy to said energizing means after same has been energized and to increase said energy to said energizing means after same has been de-energized for producing said reciprocating movements of said element and said input forces to operate said integrating means.

2. In a control device fora mechanism having a surface subject to the formation thereon of a solid but meltable material, an electric circuit operatively associated with said mechanism in normal operation thereof, the combination of; control means for effecting a change in the quantity of said material forming on said surface, initiating means to periodically cause operation of said control means when said material has formed to an undesirable quantity on said surface, a relatively small source of electrical energy provided by said circuit, said initiating means including power means having a movable heat-responsive element aifected by said energy source to provide a small pulsating input power force, said initiating means also including force-amplifying means operated by said input force of said power means to integrate and store said energy over a period of time for providing an amplified output force substantially larger than said input power force available to cause operation of said control means, said amplifying integrating means including means to release said stored energy after said period of time to produce said amplified output force for operating said control means, said power means including electric heating means mounted near said element and connected in said electric circuit to provide said small energy to heat said element for causing reciprocating movements thereof and simultaneously said pulsating input forces, switch means in said circuit operated by said element to reduce the energy to said heating means after said element has been heated and to increase the energy to said heating means after said element has cooled, for producing said reciprocating movements thereof and said input forces to operate said integrating means.

3. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material said mechanism including a source of energy supplied thereto in normal operation thereof, the combination of; control means for effecting a change in the quantity of said material forming on said surface, initiating means to periodically cause operation of said control means when said material has formed to an undesirable quantity on said surface, said initiating means including, power means having a movable element affected by said energy source to provide relatively small intermittent energy pulses and corresponding periodic force pulses by said element, said initiating means also including ratchet means disposed to count the number of periodic force impulses and interposed between said power means and said control means to effect intermittent movements thereof, said ratchet means including means providing amplified forces larger than said force pulses and adapted to operate said control means after a predetermined number of said pulses, said power means including energizing means mounted near said element and supplied by said source of energy for causing reciprocating movements of said element and simultaneously said force pulses, means to regulate the amount of said energy to said energizing means and operated by said element to reduce said energy to said energizing means after same has been energized and to increase said energy to said energizing means after same has been de-energized for producing said reciprocating movements of said element and said input forces to operate said ratchet means and said force-amplifying means.

4. In a defroster control device for a refrigerating machine having a cooling unit subject to the formation of frost thereon and including normally inactive defrosting means to provide heat for melting said frost, and an electric circuit having a source of electrical energy operatively associated with said refrigerating machine, the combination of; means to control the duration and termination of said defrosting means, means to initiate operation of said control means, said initiating means including force-amplifying means adapted to be operatively connected to said control means for periodic actuation thereof, said forceamplifying means including ratchet means having a predetermined number of ratchet teeth, electrically powered ratchet actuating means connected in said electric circuit to periodically provide electrical energy for causing movement of said ratchet means, electricity regulating means in said circuit operated by said ratchet actuating means to reduce said electric energy thereto after said actuating means has been energized and to increase the electric energy thereto after said actuating means has been de-energized, to provide continuous cycle operation of said regulating means and to cause said movement of said ratchet means one tooth-length upon each cycle-operation of said regulating means, and said force-amplifying means including means to cause said initiation of said control means after a predetermined number of cycles of said regulating means.

5. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material said mechanism including a source of energy supplied thereto in normal operation thereof, the combination of; control means for effecting a change in the quantity of said material forming on said surface, initiating means to periodically cause operation of said control means when said material has formed to an undesirable quantity on said surface, said initiating means including, power means having a movable element affected by said energy source to provide a small pulsating input power force, said initiating means also including force-amplifying means operated by said input force of said power means to integrate and store said energy over a period of time for providing an amplified output force substantially larger than said input power force available to cause operation of said control means, and said amplifying integrating means including means to release said stored energy after said period of time to produce said amplified output force for operating said control means, said power means including energizing means mounted near said movable element and supplied by said source of energy for causing reciprocating movements of said movable element and simultaneously said pulsating input forces, means to regulate the amount of said energy to said energizing means and operated by said element to reduce said energy to said energizing means after same has been energized and to increase said energy to said energizing means after same has been de-energized for producing said reciprocating movements of said element and said input forces to operate said integrating means, said initiating means including initiation sensing means operable to detect the formation of said material on said surface to said undesirable quantity for enabling said output force to operate said control means upon operating said initiating means, and means producing a sensing force lesser in magnitude than and independent of said output force to enable said detecting operation of said sensing means.

6. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material, an electric circuit operatively associated with said mechanism, the combination of; control means for effecting a change in the quantity of said material forming on said surface, initiating means to periodically cause operation of said control means when said material has formed to an undesirable quantity on said surface, a relatively small source of electrical energy provided by said circuit, said initiating means including power means operated by said energy source to provide a small input power force, said initiating means also including forceamplifying means operated by said power means to integrate and store said energy over a period of time for providing an amplified output force substantially larger than said input power force available to cause operation of said control means, said amplifying means including means to release said stored energy after said period of time to produce said amplified output force for operating said control means, said power means including a bimetallic element, electric heating means connected in said electric circuit to provide said small energy and mounted adjacent said bimetallic element to heat same for causing reciprocating movements thereof to effect said operation of said power means, switch means in said circuit operated by said element to provide intermittent heating and cooling thereof to effect said reciprocating movements of said element, and snap-action means operatively associated with said bimetallic element and said switch means to produce a delayed action thereof in said reciprocating movements.

7. In a control device for a refrigeration machine subject to the formation of frost on a surface thereof, the

combination of; control means for regulating the quantity of said frost forming on said surface, initiating means operatively associated with said control means to cause operation thereof for starting the melting of said frost after forming on said surface to a substantially undesirable quantity, said initiating means including thermally-powered clock means producing a force to enable said operation of said control means after predetermined time intervals, and said initiating means including an integrating mechanism interposed between said clock means and said control means, said integrating mechanism including means to build up and store energy progressively supplied by said clock means and also including means to release said stored energy for providing a force larger than said force produced by said clock means for causing operation of said control means.

8. In a control device for a refrigeration machine subject to the formation of frost on a surface thereof, the combination of; control means including heating means for regulating the quantity of said frost: forming on said surface, initiating means operatively associated with said control means to cause operation thereof for starting the melting of said frost after forming on said surface to a substantially undesirable quantity, said initiating means including thermally-powered clock means intermittently operated through a predetermined time cycle, said clock means having a power element including a mechanism to count the number of said time cycles to cause said operation of said control means after a predetermined number of said time cycles, and means for terminating the melting action of said heating means when said frost has melted, said terminating means including a movable sensing member abutting some ice in said machine while said heating means is operated and adapted to cause termination of said ice-melting action after a predetermined travel of said sensing member.

9. In a control device for a refrigeration machine subject to the formation of frost on a surface thereof, the combination of; control means for regulating the quantity of said frost forming on said surface, initiating means operatively associated with said control means to cause operation thereof for starting the melting of said frost after forming on said surface to a substantially undesirable quantity, said initiating means including thermallypowered clock means having a power element intermittently operated through a predetermined time cycle to produce a corresponding periodic input force, said clock means including a mechanism to count the number of said time cycles to cause said operation of said control means after a predetermined number of said cycles, and said initiating means including force-amplifying means operatively associated with said counting means for providing upon said predetermined number of cycles a force to said control means larger than said force produced by said power element.

10. In a control device for a refrigeration machine subject to the formation of frost on a surface thereof, a source of electric energy supplied to said machine through an electric circuit, the combination of; control means for regulating the quantity of said frost forming on said surface, initiating means operatively associated with said control means to cause operation thereof for starting the melting of said frost after forming on said surface to a substantially undesirable quantity, said initiating means including thermally-powered clock means to enable said operation of said control means after a plurality of predetermined time intervals, said thermally powered means including a bimetal element to provide each said time interval, electric heating means mounted near said element and connected to said source of electric energy to heat said element for causing operation thereof, switch means in said circuit operated automatically by said element to reduce said electric energy to said heating means after said element has been heated and to increase said electric energy to said heating means after said element 19 has cooled to provide a time cycle corresponding to one said time interval.

11. In a control device for a refrigeration machine subject to the formation of frost on a surface thereof, a source of electric energy supplied to said machine through an electric circuit, the combination of; control means for regulating the quantity of said frost forming on said surface, initiating means including sensing means providing a low force acting periodically on said frost to detect the thickness thereof and operatively associated with said control means to cause operation thereof for starting the melting of said frost after forming on said surface to a substantially undesirable quantity, said initiating means including thermally-powered clock means producing an actuating force separate from and larger than said sensing force to cause said operation of said control means after a plurality of predetermined time intervals, said thermally powered means including a bimetal element to provide each said time interval, electric heating means mounted near said element and connected to said source of electric energy to heat said element for causing reciprocating movements thereof, switch means in said circuit operated automatically by said element to reduce said electrical energy to said heating means in one position thereof after said element has been heated and to increase said electric energy to said heating means after said element has cooled in another position thereof to cause said reciprocating movements and provide a time cycle corresponding to one said time interval, and said clock means including a mechanism to count the number of said time cycles to cause said operation of said control means after said predetermined number of said cycles.

12. In a control device for a refrigeration machine subject to the formation of frost on a surface thereof, a source of electric energy supplied to said machine through an electric circuit, the combination of; control means for regulating the quantity of said frost forming on said surface, initiating means operatively associated with said control means to cause operation thereof for starting the melting of said frost after forming on said surface to a substantially undesirable quantity, said initiating mean including thermally-powered clock means to enable said operation of said control means after a plurality of predetermined time intervals, said thermally powered means including a bimetal element to provide each said time interval, electric heating means mounted near said element and connected to said source of electric energy to heat said element for causing reciprocating movements thereof, switch means in said circuit operated automatically by said element to reduce said electrical energy to said heating means in one position thereof after said element has been heated and to increase said electric energy to said heating means after said element has cooled in another position thereof to cause said reciprocating movements and provide a time cycle corresponding to one said time interval, and snap-action means operatively associated with said bimetal element and said switch means to produce a delayed action of said element in said reciprocating movements thereof from one of said positions to the other of said positions to establish said time cycle, said clock means including force-amplifying means and also including a counting mechanism operated by said bimetal element in said snap-action movements thereof to develop and output force larger than said input force after a predetermined number of said cycles, said force-amplifying means including an actuating member adapted'to transmit said output force to said control means to cause movements thereof, said actuating member including means operable substantially at the end of said last-named movements for enabling said control means to operate independently of said bimetal element.

13. In a mechanism having a movable member requiring automatic intermittent actuation thereof, a source of heat energy associated with said mechanism and adapted to cause said automatic actuation of said member, the combination of; thermally powered clock means operatively associated with said movable member, said clock means including a heat-responsive element intermittently operated by pulses of said heat energy in which each pulse corresponds to a substantially predetermined time interval, said clock means including a mechanism to count the number of heat pulses to cause said automatic actuation of said movable member after a predetermined number of said pulses, whereby said actuation of said movable member is enabled after a predetermined number of said time intervals, and said clock means including means to preclude said actuation of said member after at least the next said predetermined number of said pulses following each said actuation of said member.

14. In a control mechanism for a refrigeration machine having a surface subject to the formation of ice thereon, said mechanism having a movable member re quiring automatic intermittent actuation thereof to cause initiation of a melting action of said ice, the combination of; clock means operatively associated with said movable member and including means to provide a predetermined input force, integrating means operatively associated with said clock means and including means to store energy, said integrating means also including means automatically to release said stored energy for causing movements of said member with an output force larger than said input force, and means operatively associated with said integrating means and operable substantially at the end of said movements of said member for enabling said member to operate substantially independently of said integrating mechanism.

15. In a mechanism having a movable member requiring automatic intermittent actuation thereof, a source of energy associated with said mechanism and adapted to cause said automatic actuation, the combination of; clock means operatively associated with said actuated member, said clock means including an element intermittently operated by pulses of said energy to provide an input force in which each pulse corresponds to a substantially predetermined time interval, said clock means including a mechanism to count the number of pulses for causing said automatic actuation of said movable member after a predetermined number of said pulses, whereby said actuation of said member is enabled after a predetermined number of said time intervals, forceamplifying means operatively associated with said clock means for automatically actuating said movable member with an output force larger than said input force, and said clock means including means to preclude said actuation of said member after at least the next said predetermined number of said pulses following each said actuation of said member.

16. In a mechanism having a movable member requiring automatic intermittent actuation thereof, a source of electric energy in a circuit associated with said mechanism, the combination of; a heat-responsive power element operatively associated with said movable member, electric heating means mounted near said element and connected in said electric circuit for heating said element and causing reciprocating movements thereof to provide a small input power force, switch means in said circuit operated automatically by said element in a continuous repetitive cycle to reduce the energy from said heating means after said element in one position thereof has been heated and to increase the energy from said heating means after said element in a second position thereof has cooled for producing said reciprocating movements and said input force, integrating means operated by said element in said cycling thereof and including means to store a portion of said energy upon a predetermined number of said cycles, actuating means operatively associated with said integrating means, said integrating means also including means automatically to release said stored energy for producing an output force larger than said input force acting on said actuating means to cause said intermittent automatic actuation of said movable member, said actuating means including means operable substantially at the end of said last-named intermittent actuation for enabling said movable member to operate independently of said integrating means.

17. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material, a source of electric energy in a circuit associated with said mechanism, the combination of; control means for effecting a change in the quantity of said material forming on said surface, a heat-responsive bimetal power element operatively associated with said control means to cause periodic actuation thereof for melting said material formed on said surface, electric heating means mounted near said bimetal element and connected in said electric circuit for heating said element and cansing reciprocating movements thereof to provide a small input power force, switch means in said circuit operated automatically by said element in a continuous repetitive cycle to reduce the energy from said heating means after said element in one position thereof has been heated and to increase the energy from said heating means after said element in a second position thereof has cooled for producing said reciprocating movements and said input force, integrating means operated by said bimetal element in said cycling thereof and including means to store a portion of said energy after a predetermined number of said cycles, actuating means operatively associated with said integrating means, said integrating means also including means to release said stored energy for producing an output force larger than said input force acting on said actuating means to cause said periodic actuation of said control means for initiating said melting action, said actuating means including means operable substantially at the end of said last-named periodic actuation for enabling said control means to operate substantially independently of said integrating means for terminating said melting action, and snap-action means operatively associated with said bimetal element to delay each movement thereof from one of said positions to the other said position for establishing a predetermined period of time for said cycle.

18. In a mechanism having a movable member requiring intermittent actuation thereof, a source of electric energy in a circuit associated with said mechanism, the combination of; a heat-responsive bimetal power element operatively associated with said movable member, electric heating means mounted near said bimetal element and connected in said electric circuit for heating said element and causing reciprocating movements thereof to provide a small input power force, switch means in said circuit operated automatically by said element in a continuous repetitive cycle to reduce the energy from said heating means after said element in one position thereof has been heated and to increase the energy from said heating means after said element in a second position thereof has cooled for producing said reciprocating movements and said input force, and said bimetal element including means providing a snap-action thereof to delay each movement of said element from one of said positions to the other said position for establishing a predetermined period of time for said cycle, force-amplifying means including a counting mechanism operated by said bimetal element in said snap-action cycle movements thereof to develop an output force larger than said input force upon a predetermined number of said cycles, said force-amplifying means including an actuating member adapted to transmit said output force to said actuated member to cause movements thereof, said actuating member including operable substantially at the end of said last-named movements of said actuated member for enabling said actuated member to operate independently of said bimetal element.

19. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material, the combination of; control means for effecting a change in the thickness of said material forming on said surface, link means operatively connected to said control means for actuation thereof, actuating means adapted to occassionally operate said link means and including an intermittently movable actuating element, sensing means having a portion movable toward and away from said surface in movements relative to said element in response to said intermittent movements thereof when said material has formed to an amount less than a predetermined thickness, a support member operatively connecting said sensing means and said link means for supporting same to enable said actuating element to clear and pass by said link means upon said corresponding relative movement of said element and said sensing means when said material has formed to a quantity less than a said predetermined thickness on said surface, said sensing means being disposed to abut said material when formed to said predetermined thickness to block said movement of said sensing means for preventing said relative movement thereof, said support member and said link means during said blocking action including means to enable said actuating element to be operatively connected to said link means and said control means for operation thereof at the first of said intermittent movements of said element following formation of said material to said predetermined thickness, for effecting a reduction in the thickness of said material.

20. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material, the combination of; control means for effecting a change in the thickness of said material forming on said surface, link means hingeably connected to said control means for angular movements in relation thereto for actuation thereof, actuating means adapted to occasionally operate said link means and including an intermittently movable actuating element, sensing means having a portion movable toward and away from said surface in movements relative to said element in response to said intermittent movements thereof when said material has formed to an amount less than a predetermined thickness, a swingable support member hingeably connected to said sensing means and said link means for supporting same to enable said actuating element to clear and pass by said link means upon said corresponding relative movement of said element and said sensing means when said material has formed to a quantity less than a predetermined amount on said surface, said sensing means being disposed to abut said material when formed to said predetermined thickness to block said movement of said sensing means for preventing said relative movement thereof, said support member and said link means during said blocking action including means to enable said actuating element to be operatively connected to said link means and said control means for operation thereof at the first of said intermittent movements of said element following formation of said material to said predetermined thickness, for effecting a reduction in the thickness of said material.

21. In a control device for a mechanism having a surface subject to the formation thereon of a solid but meltable material, the combination of; control means for ef fecting a change in the thickness of said material forming on said surface, link means operatively connected to said control means for actuation thereof, actuating means adapted to occasionally operate said control means and including an intermittently movable actuating element, sensing means having a portion movable toward and away from said surface in movements relative to said element in response to said intermittent movements thereof when said material has formed to an amount less than a predetermined thickness, cam means operatively associated with said element and said sensing means to cause said relative movement, a support member operatively connecting said sensing means and said link means for supporting same to enable said actuating element to clear and pass by said link means upon said corresponding relative movement of said element and said sensing means when said material has formed to a quantity less than a predetermined amount on said surface, said sensing means being disposed to abut said material when formed to said predetermined thickness to block said movement of said sensing means for preventing said relative movement thereof, said support member and said link means during said blocking action including means to enable said actuating element to be operatively connected to said link means and said control means for operation thereof at the first of said intermittent movements of said element following formation of said material to said predetermined thickness, for effecting a reduction in the thickness of said material.

22. In a control device associated with apparatus having a surface subject to the formation of a solid but meltable material thereon, the combination of means including switch means to control the quantity of said material formed on said surface, a switch-actuating link member operatively connected to said control means to effect operation thereof, drive means having an inactive position and an active position, initiation sensing means movable toward and away from said surface in response to said movements of said drive means, a support arm operatively connected to said sensing means and said link member for supporting same to move said member clear of said drive means when less than a predetermined quantity of said material exists on said surface and said drive means is moved from its inactive position to its active position, said support arm also acting on said link member to position said member relative to said drive means to enable cooperative engagement therewith for operation of said switch means when said predetermined quantity of material has formed on said surface and said drive means moves from its inactive position to its active position, for initiating the reduction of said material.

23. In a control device associated with apparatus having a surface subject to the formation of ice thereon, the combination of; means including switch means to control the quantity of ice formed on said surface, a switchactuating link member operatively connected to said control means to effect operation thereof, drive means having an inactive position and an active position, initiation sensing means movable toward and away from said surface in response to said movements of said drive means, a support arm operatively connected to said sensing means and said link member for supporting same to move said member clear of said drive means when less than a predetermined quantity of ice exists On said surface and said drive means is moved from its inactive position to its active position, said support arm also acting on said link member to position said member relative to said drive means to enable cooperative engagement therewith for operation of said switch means when said predetermined quantity of ice has formed on said surface and said drive means moves from its inactive position to its active position for initiating the melting of ice, means to terminate said ice-melting action including a termination sensing member having a portion positioned in a predetermined relationship with respect to some ice located near said surface, force-producing means activated by said drive means upon initiation of said melting action and disposed to act on said termination sensing member, said force of said force-producing means acting to cause said termination sensing member to abut against some ice located near said surface and tending to compress same against a fixed abutment associated with said apparatus and gradually move with said abutted ice as same progressively melts, and means to effect a disengagement of said control means from said termination sensing member after movement thereof a predetermined distance 24 for terminating the ice'melting action, whereby the cycle can be repeated.

24-. In a control device for apparatus having a surface subject to the formation of frost adjacent thereto, the combination of; control means for regulating the amount of said frost forming on said surface, a termination sensing member carrying a frost-sensing element positioned near said surface for enabling frost to form adjacent said element and normally disconnected from said control means, said frost-sensing element including means disposed for operative connection with said member in a manner enabling sufficient movement relative thereto for enabling self-aligning flush contact with said surface, initiating means to actuate said control means and to operatively connect said control means to said sensing member and said element for initiating a melting action of said frost, biasing means to cause said thenconnected frost-sensing element to abut against said frost tending to compress same against a fixed abutment associated with said apparatus and to cause said element to gradually move with said frost as it progressively melts, said frost-sensing element having suflicient area contacting said surface and sufficient area acting on said frost in said compression thereof to provide an adequate time interval for a first defrosting cycle and subsequent defrost cycles, and means to effect a disengagement of said connection after said frost has melted a predetermined amount for terminating said frost-melting action.

25. In a defroster control device for a refrigerating machine having a surface subject to the formation of frost thereon and including normally inactive defrosting means to effect a melting of said frost, the combination of; control means to initiate intermittent operation of said defrosting means for melting said frost after same forms on said surface to an undesirable amount, means to terminate said frost-melting action when substantially all said frost has melted, said terminating means including an initially empty vessel positioned in definite relation to a fixed portion of said refrigerating machine, said terminating means also including sensing means having a portion disposed within said vessel, a frost-sensing starter member operatively connected to said sensing means in a manner enabling sufficient movement relative thereto for self-aligning flush contact with said surface to accumulate frost adjacent said member, biasing means to cause said frost-sensing starter member to abut against said frost tending to compress same against a fixed abutment associated with said machine and to cause said sensing means and said starter member to move gradually a predetermined distance during a first defrosting cycle while held against the unmelted portion of said frost by said biasing means as said frost gradually melts to cause a first termination of said first defrosting cycle, said frostsensing starter member having a sufficient area contacting said surface and sufficient area acting on said frost in said compression thereof to provide an adequate time interval for said first defrosting cycle to enable subsequent defrost cycles, said vessel being mounted to be in the flow path of said melting frost which re-freezes to ice for partially filling said vessel after said first termination, and in subsequent defrosting cycles said frost termination being repeated to progressively and automatically fill said vessel with ice to its operating level, said portion of said sensing means being urged by said biasing means to abut said ice simultaneously with said frost-abutting action action by said frost-sensing member to establish the amount of said predetermined distance, whereby said termination at said operating level of ice depends on both said frost and said ice while abutted by said member and said sensing means, respectively.

26. In a control device for a refrigeration system subject to the formation of ice on a surface thereof, and an electric circuit associated with said system, the combination of; control means including a switch in said circuit for regulating the amount of said ice forming on said surface, initiating means to effect operation of said control means for starting the melting of said ice when formed to an undesirable amount, means to inactivate said control means to effect termination of said ice-melting action when substantially all said ice formed on said surface has melted, said switch having a pair of contacts normally separated but in abutment during said ice-melting action, means for moving one of said contacts in relation to the other contact, and thermally responsive safety means acting on said moving means for enabling said contacts to open at any time the ambient temperature attains a predetermined maximum value.

27. In a control device for a refrigeration system subject to the formation of ice on a surface thereof, and an electric circuit associated with said system, the combination of; control means in said circuit for regulating the amount of said ice forming on said surface, initiating means including a clock mechanism to effect automatic operation of said control means after a predetermined time interval for starting the melting of said ice when formed to an undesirable amount, means to inactivate said control means to effect termination of said ice-melting action when substantially all said ice formed on said surface has melted, and lost-motion means between said clock mechanism and said control means to enable operation thereof after a predetermined time interval determined by said clock mechanism.

28. In a control device for a refrigeration machine subject to the formation of ice on a surface thereof, the combination of; control means for regulating the quantity of said ice forming on said surface, initiating means including drive means operatively associated with said control means to cause operation thereof for starting the melting of said ice after forming on said surface, said initiating means including an integrating mechanism interposed between said drive means and said control means, said integrating mechanism including means to store energy and also including means to release said stored energy for providing a force larger than said force produced by said drive means for causing operation of said control means, means to terminate said ice-melting action including a termination sensing member contact-ing some ice located near said surface, force-producing means activated by said initiating means upon starting said melting action and disposed to act on said termination sensing member, said force of said force-producing means acting to cause said termination sensing member to abut against some ice located near said surface and tending to compress same against a fixed abutment associated with said apparatus and gradually move with said abutted ice as same progressively melts, and means to effect a disengagement of said control means from said termination sensing member after movement thereof a predetermined distance for terminating the ice-melting action, whereby the cycle can be repeated.

29. in a mechanism having a movable member requiring intermittent actuation thereof by an actuating force, the combination of; a source of energy, force-producing means operated by said energy for providing a small input force, rotary means operated by said input force to cause relatively slow rotation thereof, detent means operatively connected to said rotary means, rotatable driving means including means to engage said detent means for rotation with said rotary means, power means operated by said driving means to be moved slowly upon rotation of said rotary means for progressively storing said energy by increasing correspondingly the available actuating force, movable actuator means subjectable to said actuating force and including restraining means to prevent movement of said actuator means while said power means gradually stores said energy to a predetermined amount, and means to release said restraining means after said rotary means has rotated a predetermined angular travel for releasing said stored energy and enabling said actuator means to operate said movable member with said actuating force.

it}. In a mechanism having a movable member requiring intermittent actuation thereof by an actuating force, the combination of; a source of energy, force-producing means operated by said energy for providing a small input force, rotary means operated by said input force to cause relatively slow rotation thereof, detent means operatively connected to said rotary means, rotatable driving means including means to engage said detent means for rotation with said rotary means, power means operated by said driving means to be moved slowly upon rotation of said rotary means for progressively storing said energy by increasing correspondingly the available actuating force, movable actuator means subjectable to said actuating force and including restraining means to prevent said movement while said power means gradually stores said energy to a predetermined amount, means to release said restraining means after said rotary means has rotated a predetermined angular travel for releasing said stored energy and enabling said actuator means to operate said movable member with said actuating force, and said actuator means including means acting on said detent means at the end of said movement of said actuator means to release said driving means for causing said actuator means to be operatively disconnected from said rotary means, and means including biasing means to return said actuator means and said power means to their original positions ready for another energy-storing cycle.

31. In a mechanism having a movable member requiring intermittent actuation thereof by an actuating force, the combination of; a source of electrical energy supplied in an electric circuit, force-producing means operated by said energy for providing a small pulsating input force, rotary means operated by said input force to cause relatively slow rotation thereof, detent means operatiyely connected to said rotary means, rotatable driving means including means to engage said detent means for rotation with said rotary means, power means operated by said driving means to be moved slowly upon rotation of said rotary means for progressively storing said energy by increasing correspondingly the available actuating force, movable actuator means subjectable to said actuating force and including restraining means to prevent said movement while said power means gradually stores said energy to a predetermined amount, means to release said restraining means after said rotary means has rotated a predetermined angular travel for releasing said stored energy and enabling said actuator means to operate said movable member with said actuating force, said forceprod'ucing means including a heat-responsive element, electric heating means mounted near said element and connected in said electric circuit to provide said small energy to heat said element for causing reciprocating movements thereof and simultaneously said pulsating input forces, switch means in said circuit and operated by said element to reduce the energy to said heating means after said element has been heated and to increase the energy to said heating means after said element has cooled, for producing said reciprocating movements thereof and said input forces to operate said integrating means, and ratchet means interposed between said force-producing means and said rotary means to translate said intermittent input forces into unidirectional forces acting on said rotary means for effecting rotation thereof.

with said rotary means, power means operated by said driving means to be moved slowly upon rotation of said rotary means for progressively storing said energy by increasing correspondingly the available actuating force, movable actuator means subjectable to said actuating force and including restraining means to prevent said movement while said power means gradually stores said energy to a predetermined amount, means to release said restraining means after said rotary means has rotated a predetermined angular travel for releasing said stored energy and enabling said actuator means to operate said movable member with said actuating force, said forceproducing means including an element affected by said source of energy to provide said small pulsations of said input power force for causing operation of said element, means to regulate the amount of said energy affecting said element and operated thereby to reduce said energy after said element has been energized and to increase said energy after said element has been de-energized, for producing intermittently said input forces to operate said integrating means, and means interposed between said force-producing means and said rotary means to translate said pulsating input forces into unidirectional forces acting on said rotary means for effecting rotation thereof.

33. In a control device for a refrigeration system subject to the formation of ice on a surface thereof, the combination of: control means for regulating the amount of said ice forming on said surface, initiating means to effect operation of said control means for starting the melting of said ice when formed to an undesirable amount, a source of energy, said initiating means including; force-producing means operated by said energy for providing a small input force, rotary means operated by said input force to cause relatively slow rotation thereof, detent means operatively connected to said rotary means, rotatable driving means including means to engage said detent means for rotation with said rotary means, power means operated by said driving means to be moved slowly upon rotation of said rotary means for progressively storing said energy by increasing correspondingly the available actuating force, movable actuator means subjectable to said actuating force and including restraining means to prevent said movement While said power means gradually stores said energy to a predetermined amount, means to release said restraining means after said rotary means has rotated a predetermined angular travel for releasing said stored energy and enabling said actuator means to operate said control means with said actuating force; and means to inactivate said control means to effect termination of said ice-melting action when substantially all said ice formed on said surface has melted.

34. In a control device for a refrigeration machine subject to the formation of ice on a surface thereof, the combination of: control means for regulating the qauntity of said ice forming on said surface, initiating means operatively associated with said control means to cause operation thereof for starting the melting of said ice, said initiating means including thermally-powered clock means having a bimetal element intermittently operated through a predetermined time cycle, a heater for actuating said element, switch means operated by said element to energize said heater after said element cools and de-energize said heater after said element is heated to provide said intermittent operation thereof, said clock means including a mechanism to count the number of said time cycles to cause said operation of said control means after a predetermined number of said time cycles, means to terminate said ice-melting-action including termination sensing means contacting some ice located near said surface, force-producing means activated by said initiating means upon starting said melting action and disposed to act on said termination sensing means for causing same to abut against said last-named ice and gradually move therewith as said ice progressively melts.

35. In a control device for a refrigeration machine subject to the formation of ice on a surface thereof, a source of electric energy supplied to said machine through an electric circuit, the combination of: control means for regulating the quantity of said ice forming on said surface, initiating means operatively associated with said control means to cause operation thereof for starting the melting of said ice, said initiating means including thermally-powered means to enable said operation of said control means after a plurality of predetermined time intervals, said thermally powered means including a bimetal element, electric heating means mounted near said element and connected to said source of electric energy to heat said element for causing operation thereof, switch means in said circuit operated automatically by said element to reduce said electric energy to said heating means after said element has been heated and to increase said electric energy to said heating means after said element has cooled to provide a time cycle corresponding to one said time interval, means to terminate said ice-melting action including a termination sensing member contacting some ice located near said surface, force-producing means activated by said initiating means upon starting said melting action and disposed to act on said termination sensing member, said force of said force-producing means acting to cause said termination sensing member to abut against said last-named ice located near said surface and tending to compress same against a fixed abutment associated with said machine and gradually move with said abutted ice as same progressively melts, and means to effect a disengagement of said control means from said termination sensing member after movement thereof a predetermined distance for terminating the ice-melting action, whereby the cycle can be repeated.

36. In a control device associated with apparatus having a surface subject to the formation of frozen substance adjacent thereto, the combination of: means to control the melting of said frozen substance, actuating means periodically movable without operating said control means during one thickness-condition of said substance but adapted to operate said control means during a second thickness-condition of said substance, sensing means including a sensing element movable toward and away from said surface to abut said substance in response to movement of said actuating means to preclude said actuating means from operating said control means at least in one substanceabutting position of said element corresponding to said first-named thickness-condition when said formation of said frozen substance is less than a predetermined thickness, said sensing element in a second substance-abutting position thereof corresponding to said second thicknesscondition being adapted to enable said actuating means to be operatively connected to said control means for operation thereof when said frozen substance has formed to substantially said predetermined thickness for initiating said melting action, power means operatively associated with said actuating means to cause said movements thereof, said power means including thermally-powered clock means and including a bimetal element intermittently operated through a predetermined time-cycle, a heater for actuating said element, switch means operated by said element to energize said heater after said element cools and tie-energize said heater after said element is heated to provide said intermittent operation thereof, said clock means including a mechanism to count the number of said time-cycles to cause said movement of said actuating means after a predetermined number of said cycles.

37. In a mechanism having a member requiring intermittent actuation thereof, the combination of: clock means to operate said member after a predetermined time interval, movable actuating means automatically operated from an initial position suddenly and rapidly to a second position by said clock means for actuating said member at the end of said time interval, and said actuating means including means automatically operable at substantially the end of said movement thereof for enabling said actuating means to return instantly and rapidly to said initial position.

38. In a mechanism having a movable member requiring intermittent actuation thereof by an actuating force, the combination of; a source of energy, force-producing means operated by said energy for providing a small input force, rotary means operated by said input force to cause relatively slow rotation thereof, power means operated by said rotary means and adapted to be moved slowly upon rotation of said rotary means for progressively storing said energy by increasing correspondingly the available actuating force, movable actuator means subjectable to said actuating force and including restraining means to prevent movement of said actuator means while said power means gradually stores said energy to a predetermined amount, and means operatively associated with said rotary means and said power means to automatically release said restraining means after said power means has traveled a predetermined amount for releasing said stored energy and for enabling said actuator means to operate said movable member with said actuating force.

39. In a mechanism having a movable member requiring intermittent actuation thereof by an actuating force, the combination of; a source of energy, force-producing means operated by said energy for providing a small intermittent input force, rotary means operated by said input force to cause relatively slow rotation thereof, power means operated by said rotary means and adapted to be moved slowly upon rotation thereof for progressively storing said energy by increasing correspondingly the available actuating force, movable actuator means subjectable to said actuating force, restraining means including detent means to prevent movement of said actuator means while said power means gradually stores said energy to a predetermined amount, means operatively associated with said rotary means and said power means to release said restraining means after said power means has traveled a predetermined amount for releasing said stored energy and for enabling said actuator means to operate said movable member with said actuating force, said force-producing means including a movable element affected by said source of energy to provide small pulsations of said input power force for causing intermittent movements of said element, means to regulate the amount of said energy affecting said element and operated thereby to reduce said energy after said element has been energized and to increase said energy after said element has been de-energized, for producing intermittently said input forces, and means interposed between said force-producing means and said rotary means to translate said intermittent input forces and corresponding movements of said element into unidirectional forces acting on said rotary means for effecting intermittent rotation thereof.

40. In a control device for a refrigeration system subject to the formation of ice on a surface thereof, the combination of; control means for regulating the amount of said ice forming on said surface, initiating means to eifect operation of said control means for starting the melting of said ice when formed to an undesirable amount, a source of energy, said initiating means including force-producing means operated by said energy for providing a small input force, rotary means operated by said input force to cause relatively slow rotation thereof, power means operated by said rotary means and adapted to be moved slowly upon rotation of said rotary means for progressive-1y storing said energy by increasing correspondingly the available actuat ing force, movable actuator means subjectable to said actuating force, restraining means to prevent movement of said actuator means while said power means gradually stores said energy to a predetermined amount, means operatively associated with said rotary means and said power means to release and rest-raining means after said power means has traveled a predetermined amount for releasing said stored energy and for enabling said actuator means to operate said movable member with said actuating force, and means to inactivate said control means to effect termination of said ice-melting action when substantially all said ice formed on said surface has melted.

41. In a control mechanism for a refrigeration machine having a surface subject to the formation of ice thereon, said mechanism having a member requiring intermittent actuation thereof, the combination of; timing means to operate said'member after a predetermined time interval to initiate a melting action of said ice, movable actuating means movable from an initial position to a second position by said timing means for actuating said member at the end of said time interval, and said actuating means including means operable at substantially the end of said movement thereof for enabling said actuating means to be returned automatically to said initial position independent of said timing means.

42. In a control mechanism for a refrigeration machine having a surface subject to the formation of ice thereon, said mechanism having a movable member requiring intermittent actuation thereof by an actuating force, to cause initiation of a melting action of said ice, the combination of; a source of energy, force-producing means operated by said energy for providing small intermittent input force pulses, rotary means operated by said input force to cause relatively slow intermittent rotation thereof, said rotary means including pinion gear means rotatable therewith, and actuating means including rack means driven by said pinion gear means upon said intermittent rotation of said rotary means for causing automatic operation of said movable member after a predetermined number of said intermittent force pulses.

43. In a control device for a refrigeration system subject to the formation of ice on a surface thereof, the combination of; control means for regulating the amount of said ice forming on said surface, initiating means to effect operation of said control means for starting the melting of said ice when formed to an undesirable amount, a small source of energy, said initiating means including forceproducing means operated by said energy for providing a small input force, said initiating means also including rotary means operated by said input force to cause relatively slow rotation thereof, said force-producing means including .a movable element affected by said source of energy to provide small pulsations of said input power force for causing intermittent movements of said element, mean-s to regulate the amount of said energy affecting said element and operated thereby to reduce said energy after said element has been energized and to increase said energy after said element has been de-energized, for producing intermittently said input forces, means interposed between said force-producing means and said rotary means to translate said intermittent input forces and corresponding movements of said element into unidirectional forces acting on said rotary means for effecting intermittent rotation thereof, said rotary means including pinion gear means rotatable therewith, said initiating means including rack means driven by said pinion gear means upon said intermittent rotation of said rotary means for causing said ice-melting operation of said control means after a predetermined num-ber of said intermittent. movements of said element, and means to inactivate said control means to effect termination of said ice-melting action when substantially all said ice formed on said surface has melted.

44. A defrost control for a refrigerating system c0mprising in combination; a sensing member movable to indicate the presence of frost on a refrigerating system, bimetal means for causing a series of small actuating forces at periodic intervals, means for converting a series of said small actuating forces into a single large actuating force, means permitting movement of said sensing member when said single large actuating force is exerted provided ice has not built up to a maximum predetermined thickness on a refrigerating system, a heater for actuating the bimetal means for developing the series of small actuating forces, switch means openated automatically by said 31 bimetal means to energize and deenergize the heater, and means operated by said large actuating force when the sensing member is in engagement with a maximum predetermined thickness of frost on the refrigerating system for initiating the defrost action.

References Cited UNITED STATES PATENTS 2,117,211 5/1938 Reutter 60-23 X 2,436,735 2/1948 Walder et a1 60-23 2,487,154 11/1949 Lloyd 60-23 X 32 McCloy 62-153 X Morton 62-140 Philipp 62-154 Perry 62-153 X Hubacker 62-276 Matthies 62-140 Carrel 23 6-93 X MEYER PERLIN, Primary Examiner.

10 ROBERT A. OLEARY, Examiner.

W. E. WAYNER, Assistant Examiner.

Claims

1. IN A CONTROL DEVICE FOR A MECHANISM HAVING A SURFACE SUBJECT TO THE FORMATION THEREON OF A SOLID BUT MELTABLE MATERIAL SAID MECHANISM INCLUDING A SOURCE OF ENERGY SUPPLIED THERETO IN NORMAL OPERATION THEREOF, THE COMBINATION OF; CONTROL MEANS FOR EFFECTING A CHANGE IN THE QUANTITY OF SAID MATERIAL FORMING ON SAID SURFACE, INITIATING MEANS TO PERIODICALLY CAUSE OPERATION OF SAID CONTROL MEANS WHEN SAID MATERIAL HAS FORMED TO AN UNDESIRABLE QUANTITY ON SAID SURFACE, SAID INITIATING MEANS INCLUDING, POWER MEANS HAVING A MOVABLE ELEMENT AFFECTED BY SAID ENERGY SOURCE TO PROVIDE A SMALL OPERATED BY SAID INPUT POWER FORCE, FORCE-AMPLIFYING MEANS OPERATED BY SAID INPUT FORCE OF SAID POWER MEANS TO INTEGRATE AND STORE SAID ENERGY OVER A PERIOD OF TIME FOR PROVIDING AN AMPLIFIED OUTPUT FORCE SUBSTANTIALLY LARGER THAN SAID INPUT POWER FORCE AVAILABLE TO CAUSE OPERATION OF SAID CONTROL MEANS, AND SAID AMPLIFYING INTEGRATING MEANS INCLUDING MEANS TO RELEASE SAID STORED ENERGY AFTER SAID PERIOD OF TIME TO PRODUCE SAID AMPLIFIED OUTPUT FORCE FOR OPERATING SAID CONTROL MEANS, SAID POWER MEANS INCLUDING ENERGIZING MEANS MOUNTED NEAR SAID MOVABLE ELEMENT AND SUPPLIED BY SAID SOURCE OF ENERGY FOR CAUSING RECIPROCATING MOVEMENTS OF SAID MOVABLE ELEMENT AND SIMULTANEOUSLY SAID PULSATING INPUT FORCES, MEANS TO REGULATE THE AMOUNT OF SAID ENERGY TO SAID ENERGIZING MEANS AND OPERATED BY SAID ELEMENT TO REDUCE SAID ENERGY TO SAID ENERGIZING MEANS AFTER SAME HAS BEEN ENERGIZED AND TO INCREASE SAID ENERGY TO SAID ENERGIZING MEANS AFTER SAME HAS BEEN DE-ENERGIZED FOR PRODUCING SAID RECIPROCATING MOVEMENTS OF SAID ELEMENT AND SAID INPUT FORCES TO OPERATE SAID INTEGRATING MEANS.