US2583271A - Freezer defroster - Google Patents

Description

J H. H. MELLION 2, 7

FREEZER DEFROSTER Filed Dec. 13, 1947 INVENTOR.

Z4- g- HARVEY H. MELLION Patented Jan. 22, 1952 UNITED STATES PATENT OFFICE FREEZER DEFROSIER Harvey H. Mellion, Spring Valley, N. Y.

Application December 13, 1947, Serial No; 791,522

3 Claims. 1

This invention relates to new and useful immovements in refrigeration apparatus, and, more particularly, aims to provide a novel and valuable auxiliary apparatus under governance of timemeasuring means for acting, at predetermined intervals. andeach time over a predetermined operating cycle, for defrosting the evaporator of a commercial type refrigeration apparatus.

The invention has been made with the idea of providing such an auxiliary apparatus which shall be especially useful in connection'with the defrosting of the evaporator of freezer lockers as commonly commercially manufactured, whether the evaporator be a blower type one or a plate typeone. However, since-most of the smaller freezer installations employ a blower type evaporator, an apparatus pursuant to the present invention, in view of its relatively low cost of manufacture, its simplicity and its efiiciency and reliability in operation, should particularly find wide acceptance as an economical and otherwise ideal typeofautomatic defroster for-a'blower type evaporator.

The embodiment of the invention as herein shown and described, therefore, is one for use with a freezer having a blowertype'evaporator; but that fact is to be taken as being merely in illustration of a particular adaptation of the invention and not as in anyway a limitation upon the scope of protection contemplated.

In carrying out theinvention, an apparatus is provided which, except for electrical connections to certain parts of the freezer, and except for simple d'eviceseasily added to the refrigerating apparatus; iswholiy self-complete, and is" readily em- Dlbmble' for use with a freezer'previously in use. Such easily'added' devices comprise merely a solenoid operated valve interposed in the refrigerant line, asolenoid operated valve interposed in the water'supply line for spraying the evaporator for defrosting, and, for use in connection with extremeiy cold installations, electric-resistance type heating elements for warming the water before it is sprayed and while it is being'drained off after being sprayed.

Essentially, the apparatus comprises a timemeasuring'means, that is, a time-clock having instrumentalities manually adjustable in such manner that at certain times, say once in each twenty=four hours; there will automatically be initiated; continued and completed a predetermined cycle of operations for fully yet safely defrosting the evaporator; the arrangement being also such that when'said cycle is completed, the apparatus automatically becomes reset, so as 2 automatically to repeat the cycle whennext the same is to be performed.

Each cycle comprises,- in the case of a blower type evaporator:

(a) The shutting off of the refrigerator co mpressor;

(b) The shutting off of the evaporator blower or fan;

(0) A time lapse sum'cient to allow the blower or fan to come to rest;

(d) The spraying of the evaporator with water;

(e) A time lapse sufficient to allow the evaporator'coils to cool;

(f) The restarting of the conipre'ssor;

('g) The restarting of the blower or fan;

These steps of the cycle, taken by themselves, are performed in the order just indicated.

However, in order to prevent the building up of high head pressure, an interpolative' step is performed, which involves cutting off thempply of refrigerant to the evaporator while thedefrosting" cycle isin progress-.-

Also, to meet the situation encountered in extremely cold installations, means are provided for performing two other functions; these being to keep the spray water from freezing, and simk la'rly to serve the'water' so that after being sprayed on the evaporator it may be drained off.

Consequently, the invention involves the pr'ovision of an apparatus which, in addition to being adapted automaticallytoperform the steps (a) through (9), is also adopted automaticallyand with proper timing to perform the steps of (h)' Warming the spray water before and after spraying before and after step (d) (7') Cutting off the supply of refrigerant to the evaporator' following step (b') (k) Turning on the spray water followingstep (c) (m) Cutting off the supply of spray water fol-' lowing step (d).

For" further comprehension of the invention, and of the objects and advantages thereof, reference will behad to the following desc'ription and accompanying drawing, and to" the appendedclaims in which the various novel features or ment of said self-contained apparatuses now favored, the same being shown in a lidded box, with the lid open and partially shown.

Fig. 3 is a wiring diagram, showing current conductive arrangements in the electrical devices of Fig. 2, and the solenoid operated valves aforesaid.

Referring to the drawing more in detail, and referring first to Fig. 1, an evaporator is indicated at It. Refrigerant from a compressor ii goes through a high pressure conduit l2 to a condenser i4, thence to a receiver 15, and from the latter to the evaporator 16 through a refrigerant liquid transmitting conduit l6 which includes an expansion valve Ilia. A suction conduit H withdraws the refrigerant from the evaporator and returns it to the compressor. The compressor is driven by a motor I8, and the evaporator is served by a blower or fan l9 driven by a motor 26. The freezer locker is indicated at 2 l Also, and pursuant to the invention, a solenoid operated normally open shut-off valve 22 is shown as interposed in the line for supplying refrigerant to the evaporator ii]; a Water spray means for the evaporator is indicated at 23, the same having a normally closed valve 24 solenoid-operated to open condition; a spray water collecting tray is indicated at 25 having a drain pipe 26; a heating means for the supply of spray water is indicated at 21, and a heating means for the drain water is indicated at 28.

Referring to Fig. 2, the electrically operated time-clock is shown at 29, one of the electrical relays at 36, the other at 3i, the electrically operated timer at 32, and the electrical time-delay relay at 33; these devices suitably mounted in a box 34, having an openable lid 35.

The time-clock 29 is the single pole single throw Intermatic time clock, model T. S. 41 (110 volts, 60 cycle, 35 amp.), made by International Register 00., of Chicago, Illinois. This clock is adapted for initiating an operation controlling cycle once every twenty-four hours, and may be manually set to start its operation controlling cycle at any time marking the beginning of a quarter hour period. It carries an arm or index and an associated dial 29a calibrated for each of the quarter-hour intervals over a twenty-four hour period, these are relatively adjustable and as so adjusted rotated by the clockwork mechanism, and a pair of individually adjustable coacting members one labelled On and the other labelled Off. The manually arranged spacing between these On and "Ofi members measures the desired time lapse between the starting and finishing of the electrical coaction between the time-clock and the device or devices to be controlled thereby.

In the case of the present invention, the timeclock 29, when once set, predetermines the defrosting time; that is, the time during which the complete defrosting cycle is to be performed, and also the time when the cycle is to be started. It also, as will be made plain later, establishes the length of the off time for the compressor and blower.

The relays 35 and 3| are both double pole double throw relays with 110 volt operating coil, Cat. #812l9, S. 0. 4576569, made by Ward Leonard Electric Co., of Mt. Vernon, New York.

The electrically operated timer 32 is a one minute interval, 55 minute maximum, type, having a hand manually settable at any one of the oneminute divisions around its dial 31; this timer being Cat. #P-l-H, made by Industrial Timer Corporation, of Newark, New Jersey.

made by General Valve Controls 00., of Chicago,

Illinois.

Referring now primarily to Fig. 3, as made plain by the legends thereon at the left the energizing leads for the compressor motor 18 are shown at 38 and 39 and at 46 and 46, the energizing leads for the water heating elements 21 and 28 (these of the electric-resistance type) are shown at 42 and 43, and the energizing leads for the blower motor are shown at 44 and 45 and at 46 and 41.

Further leads 46 and 40 are connected in parallel to the time-clock 29 to the relays 30 and 3|, and to the time-delay 33, as shown.

As the time-clock 29 is illustrated, the time has not yet arrived for the beginning of a defrosting cycle.

Hence the relay 30 is illustrated in its normal condition, for causing operation of the compressor; that is, with the coil 46 of said relay not yet having been energized, the relay arms 50 and 5| are now acting, respectively, to connect up the leads 39 and 46 and to connect up the leads 38 and 4|. At the same time, the back contacts 52 and 53 of the relay are disabled in regard to the leads 42 and 43 for energizing the water heating elements 21 and 28.

Hence, also, the relay 3! is illustrated in its normal condition, for causing operation of the blower; the coil 54 of the relay not yet having been energized, and the relay arms 55 and 56 now acting, respectively, to connect up the leads 46 and 45 to connect up 'the leads 4'! and 44. At the same time, the back contacts 5! and 58 are a disabled in regard to the leads 60 and 16 for energizing the solenoid of the refrigerant shut-01f valve 22. At this time also, the water spray valve is closed, due to the breaking of the part of the circuit for energizing its solenoid including the leads 6i and 62, such breaks being in the timer 32 at its relay arm 63, arranged normally as shown, and in the time-delay relay 33 at its relay arm 64.

It is to be noted that the time-delay relay 33 has, in addition to the relay arm 64, arranged normally as shown, a relay arm also arranged normally as shown and operating with the relay arm 64 on energization of a coil 66, this coil energized on energization of the relay 3|; also, a contact 69, to be engaged by the arm 64 on energization of said coil, thereby to start operation of the timer 32 by energizing its coil 68, thereby to prepare for energization of the solenoid of the water-spray valve 24.

In regard to such preparation for energiza- 'tion of said solenoid of the valve 24, it will be lead 62. This lead 62 goes through the timer 32,

and has a gap therein at the timers arm 63.

Such gap is closed by energization of the coil 610i the timer 32, causing the solenoid of the valve 24 to be energized to open the valve 24 causing water to flow from the water spray means 23. The gap closed by the timer arm 83 remains closed until the timer 32 has operated for the length of time it was set to operate by adjustment of its hand 31, at the conclusion of which operation the gap is opened and the solenoid of the valve 24 is deenergized and the waterspray is turned off.

With the relay arm 65 of the time-delay relay 33 normally in closed condition, that is, in engagement with a contact 1 I, the timer 32 is started on energization of its coil 68. Energization of said coil 68' occurs as soon as the time-clock 29 reaches its cycle-starting condition.

When this last happens, the relay 30 is operated, to shut off the compressor and to energize the water heating elements 21 and 28, and at the same time the relay 3| is operated to shut off the blower I9 and to bring into circuit the lead 10 by engagement of the arm 55 of said relay with the contact 51 of said relay.

Then, simultaneously, with energization by way of the leads 59 and 60 of the solenoid of the valve 22 for shutting off the refrigerant, the coil 68 of the timer 32 is energized, and the starting circuit for said timer is made.

However, voltage is prevented from reaching the solenoid for the water-spray valve 24 until the thermal time element 13 of the time-delay relay 33 functions to close the normally open contacts of said element 13, thereby to close the circuit for said solenoid and so turn on the waterspray. In other words, the water-spray is not turned on by opening of the valve 24 until the time-delay relay 33 has acted pursuant to its manual adjustment, which adjustment is so made as to insure that before the water-spray is turned on the blower [9 will have come to rest following deenergization of its motor 20. However, as will be noted, the refrigerant shut-off valve 22 is closed at the very initiation of the defrosting cycle.

The water-spray, started following shut-off of the refrigerant and cessation of operation of the compressor and blower, and also following the subsequent coming to rest of the rotor of the blower, continues, together with the operation of the heating means 21 and 28, until the timer 32 has operated for the length of time for which it was set for operation by the adjustment of its hand 31.

The timer 32 and the time-clock 29 are so adjusted in relation to the operating characteristic of the thermal time element 13 of the time-delay relay 33 that, following the shutting of the waterspray valve 24 by said element 13, there will be a sufllcient time lag, before the time-clock 29, by way of its ofi" member, ends the defrosting cycle by deenergizing the relays an and 3| and so restarting the compressor and blower, for the evaporator coils to have dried.

As will now be clear, the time at which a defrosting period is to start may be predetermined by the setting selected for the adjustable on member of the time-clock 29; and the length of time over which said cycle is to continue may be predetermined by the setting selected for the adjustable of! member of the time-clock 29. The setting to take care of the time-part of the cycle required for the rotor of the blower to come to rest, and for this time-part to be in its proper time-place in the cycle, is made on the timedelay relay 33, by adjustment of its thermal time element 13. The time required for-the waterspray and for this to start in its proper timeplace in the cycle, is predetermined by the settingof the timer 32. The drying time will be the difference between that partof the time interval for the entire defrosting cycle remaining after conclusion of the water-spray, and the time al-v lowed for water spraying.

Thus, for each defrosting cycle, these cycles recurring at a predetermined time during each twenty-four hours, and such time variable as to.

its place in the twenty-four hours as desired,

the length of compressor andblower idle time is.

variable, the length of blower, come-to-rest time is variable, the water-spray time is variable, and the drying time is variable. Once the apparatus is so timed, and this once when installed, no further adjustments will be required. Since all the time elements are variable, the apparatus can be installed on any style or type of refrigerating system that uses the water defrosting method.

While I have illustrated and described the preferred embodiment of my invention, it is to be understood that I do not limit myself to the precise construction herein disclosed and the right is reserved to all changes and modifications coming within the scope of the invention as defined in the appended claims.

Having thus described my invention, what I claim as new, and desire to secure by United States Letters Patent is:

1. An auxiliary apparatus for defrosting a refrigerating system of the kind including an electrically operated compressor, an electrically operated blower, an evaporator, a refrigerant supply line from said compressor to the evaporator and a water-spray defrosting means for the evaporator, comprising a normally open solenoid operated valve in the supply line to be energized to close and stop the flow of refrigerant when defrosting is to take place, normally inoperative heating means beneath the evaporator and on the water-spray means, a normally closed solenoid operated valve on the water-spray means to be energized to open and start the flow of water from the spray means onto the evaporator, and manually settable circuit means for stopping operation of the compressor and the blower, for closing said normally open solenoid, for energizing said heating means and for opening said normally closed solenoid.

2. An auxiliary apparatus for defrosting a refrigerating system of the kind including an electrically operated compressor, an electrically operated blower, an evaporator, a refrigerant supply line from said compressor to the evaporator and a water-spray defrosting means for the evaporator, comprising a normally open solenoid operated valve in the supply line to be energized to close and stop the flow of refrigerant when defrosting is to take place, normally inoperative heating means beneath the evaporator and on the waterspray means, a normally closed solenoid operated valve on the water-spray means to be energized to open and start the flow of water from the spray means onto the evaporator, and manually settable circuit means for stopping operation of the compressor and the blower, for closing said normally open solenoid, for energizing said heating means and for opening said normally closed solenoid, said circuit means including an electrically operated main time measuring means having manually settable controls for predetermining the start of a defrosting cycle at any time within a twentyfour hour period.

3. An auxiliary apparatus for defrosting a refrigerating system of the kind including an electrically operated compressor, an electrically operated blower, an evaporator, a refrigerant supply line from said compressor to the evaporator and a water-spray defrosting means for the evaporator. comprising a normally open solenoid operated valve in the supply line to be energized to close and stop the flow of refrigerant when defrosting is to take place, normally inoperative heating means beneath the evaporator and on the water-spray means, a normally closed solenoid operated valve on the water-spray means to be energized to open and start the flow of water from the spray means onto the evaporator, and manually settable circuit means for stopping operation of the compressor and the blower, for closing said normally open solenoid, for energizing said heating means and for opening said normally closed solenoid,

said circuit means including means for slightly delaying energization of the solenoid of said normally closed valve following energization of said circuit means.

HARVEY H. MELLION.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

Images