US2417582A

US2417582A - Automatic defrosting refrigeration system

Info

Publication number: US2417582A
Application number: US385357A
Authority: US
Inventors: Albert S Barfield
Original assignee: DUDLEY SHREVE C
Current assignee: C DUDLEY SHREVE; DUDLEY SHREVE C
Priority date: 1941-03-26
Filing date: 1941-03-26
Publication date: 1947-03-18
Anticipated expiration: 1964-03-18

Description

Mgrch 18, 1947. A. s. BARFIELD 2,417,532

AUTOMATIC DEFROSTING REFRIGERATION SYSTEM Filed March 26, 1941 INV on BY W Q,

ATTORNEYS- Patented Mar. 18,1947

AUTOMATIC DEFROSTING REFRIGERATION SYSTEM Albert S. Bar-field, Atlanta, Ga., asslgnor to i C. Dudley Slireve, Washington, D. C.

Application March 26, 1941, Serial No. 385,357

Claims. (01. 62-115) Generically this invention relates to mechani cal refrigeration but it is more particularly directed to show case refrigeration.

An important object of this invention is the provision of a defrosting system in connection with a conventional refrigerating system wherein a time controlled electromagneticaliy operated apparatus is utilized for intermittently cuttin out the conventional refrigerating circulation system and substituting, for a predetermined in terval, a defrosting circulating system, and especially adapted to quickly effect the substitution when such interval occurs under low pressure conditions between operating cycles.

In automatically and intermittently by-passing hot gases around the condenser and through the cooling coils for effecting defrosting of the latter in connection with mechanical refrigerating units or systems, wherein a pressure switch in circuit with the motor is employed, it has been found that upon initiating the defrosting operation 2 V the other valve being connected in the motor circult, open when the compressor is running and closed when the compressor stops. During the idle period of the compressor, the pressure in the line to the pressure switch drops, and when the time control mechanism operates to commence the defrosting period when the compressor is not during an idle period of the compressor, there is not sufficient pressure to operate the switch, but by blocking the hot gas line and directing the residual or trapped charge of gases in the hot gas line communicating with the compressor and the pressure switch there is sufllcient pressure, even under such low pressure conditions, to efiect quick starting of the motor and compressor. Therefore, one of the principal objects of this invention is the provision of a cut-off valve means in circuit with the motor, mounted in the hot gas line, and adapted to be closed simultaneously with stoppage of the compressor, whereby, upon initiation of the defrosting operation, the charge of said trapped gases will be directed to the pressure switch to close the motor circuit and effect quick starting of the compressor. The opening of said out off means will also permit flow of the hot gases to and through said cooling coils during the defrosting operation.

More specifically, a further object of this in vention is the provision of a defrosting apparatus in combination with a refrigerating machine,

which combination includes a motor, a comrunning, there is not sufficient pressure to im-- mediately operate said pressure switch. Therefore as thesaid time device initiates the defrosting period the valve in circuit therewith is opened permitting the charge of gases in the hot gas line, which has been prevented from flowing to the cooling coils by the other valve, to be immediately directed to the pressure switch which closes the motor circuit and effects q c S t ng of the compressor. At the same time said other valve is opened to permit the flow of the hot gases through the cooling coils during the defrosting operation.

With these and other objects in view, which will become apparent as the description proceeds, the invention resides in the construction, combination and arrangement of parts. hereinafter more fully described and claimed, and illustrated in the accompanying drawings, in which like characters of reference indicate like parts throughout the figures, of which:

Fig. 1 is an elevational plan view of a refrigerating system partly in section in conjunction with my improved defrosting system and including the wiring diagram.

Fig. 2 is a detail view of the manner of securing the free end of the feeler tube.

The usual procedure of manually cutting off the refrigeration to defrost the coils and permitting atmospheric temperature to sufilciently heat the coils to melt the encrusted ice formation presents many disadvantages, in that, often too long a time elapses before cutting off the refrigeration, and, also the time required to completely effeet the defrosting operation is such as to frequently permit the interior of the showcase or other unit to become warm, thereby causing readily perishable articles such as fish, meats, and the like to spoil, and,.therefore, it was to overcome such disadvantages and to effect an automatic defrosting apparatus having a control pressure switch in circuit with the motor, a time control valve mechanism for determining uniform defrosting periods, and means for automatically effecting icy-passing of the hot gases around the condenser and directly through the cooling coils for quickly defrosting said coils, and including;

means automatically settable by stopping of the compressor to interrupt, upon starting oi the compressor, the residual or trapped charge of the hot gases to the cooling coils at the beginning of the defrosting period, occurring during an idle period of the compressor, to operate said pressure switch and effect quick starting 01' the compressor and at the same time return said settable means to open position to permit flow of said gases through said coils during the defrosting period, and which I have accomplished by my improved defrosting system including the structural arrangement of the interrelated electrically controlled solenoid or electromagnetically operated valves, pressure switch, and time control mechanism.

In the illustrated embodiment characterizing this invention there is shown a showcase or other refrigerating box I, a cooling coil supporting or fin structure 2, which is adapted to support the cooling coils 3, under which is suitably supported the drip'pan 4, said coil supporting structure 2 being suitably connected to and supported by said case adjacent top 5.

Suitably mounted on a frame supporting structure 5 is a motor 1 adapted to operate compressor 3 by a belt or other driving connection 9. Mounted on compressor 8 is a header l0 and a pipe section I connecting said header and T connec- -tion l2 through which the heated compressed gaseous refrigerant is directed to the condenser l3 which discharges into receiver l4, said condenser |3 being suitably supported by frame sections l8 carried by frame 6. The refrigerant line H eii'ects communication between receiver l4 and expansion valve l8, which latter is connected by pipe section |9 with the T connection 20, and therewith forming a continuation of line I1 is conduit section 2| which extends upwardly and enters the coil supporting structure 2 as at 22, formingwithin said structure the cooling coils 3, and extends downwardly from outlet 23 as return or suction line 24 to the inlet end of the coil 25 and from the outlet end of said coil as section 26 to header ID for returning the refrigerant from coil 3 through coil 25 and back to compressor 8 for recirculation therethrough and through condenser l3 during the refrigerating cycle.

A feeler tube 35 has one endclosed and attached to coil 25 by a clamp 36 secured by fastening means 35' and its other end suitably attached to expansion valve I8, so that temperature variations of coil 25 will be transmitted to and effect operation of said expansion ,valve to control the flow of the refrigerant and its refrigerating action within predetermined temperature limits and operating requirements during the refrigerating cycle.

In order to by-pass the hot gases from compressor 8 through coils 3 and 25 and back to said compressor without passing through the condenser l3, for the purpose of defrosting said coils, as will be hereinafter more fully explained, a hot gas conduit 21 is connected at one end to the T connection l2 and at its other end to the solenoid or electromagnetically operable valve C by connection 21', said valve being closed during the refrigerating operation. Valve C is connected by threaded pipe connections 28, 29, and intermediate T section 30 to the solenoid valve D which is open when the motor is running, said valve D being connected by threaded pipe section 3| to check valve 32, and connecting structure 33 to one end of pipe 34, the other end of which is suitably connected to T section 20 as at 2|.

From T 20 said hot gases pass through conduit or pipe section 2|, coil 3, pipe 24, coil 25, pipe section 25, header i0, compressor 3, pipe section H, and T l2 to conduit 21 for recirculation through the coils during the defrosting operation or cycle and without passing through the condenser l3. as will be apparent.

An auxiliary hot gas pipe or conduit 31 has one end attached by connection 33 to T section 30 and the other by connection 39 to check valve .40 suitably connected to T section 4| which is connected on one side by section 42 to pressure switch B. The other side of said T ection 4| is secured by connection 43 to one end of pressure line 44, the other end of said line being connected to compressor 8 as at 45.

The time control switch, electrical connections for controlling motor 1, pressure switch B and solenoid valves C and D for effecting predetermined passage of the heated gases from the compressor without passing through the condenser l3, will now be described, and with particular reference to the solenoid D and auxiliary conduit 31 for directing and conducting the charge of said heated gases trapped in hot gas line 21 to effect operation of the pressure switch, when the defrosting operation is to be initiated by the starting of the compressor.

The electrical system for operating the various components of the apparatus comprises conductor 45 extending from the positive side of a source of electrical energy (not shown) to supply terminal 41 of Junction box E and conductor 48 from supply terminal 49 to the negative side of said source of supply completing the supply circuit to the junction box. The junction box E has feed terminals 50 and 5| connected with the supply terminals 41 and 49, respectively.

For brevity of description the remaining circuits will be described as completed from the feed terminal 50 to feed terminal 5|, since said terminals are connected to supply terminals 41 and 49, respectively, and therefore the respective circuits are in fact completed to said source through the supply circuit.

The time clock operating circuit comprises conductor 52 extending from feed terminal 50 to terminal 53 of time clock A and conductor 54 from terminal 55 to terminal 5|, which completes the clock operating circuit.

The solenoid C circuit through said time control switch comprises conductor 56 extending from feed terminal 50 to switch terminal 51, switch 58, terminal 59, and conductor 60 to solenoid C and from said solenoid conductor 6| back to feed terminal 5| of said junction box when said switch 58 is in circuit closing position.

The motor circuit comprises conductor 62 from feed terminal 50 to motor I and conductor 63 from said motor to terminal 64 of pressure switch B, switch element65, terminal 66, and conductor 61 to feed terminal 5|, which completes the circuit to the motor when switch 65 of pressure switch B is in circuit closing position. In order that solenoid valve D will be in open position when the compressor is in operation and closed when it is not, said solenoid D is connected to the motor circuit. Conductor 68 leads off from conductor 62 and extends to solenoid D and conductor 69 from said solenoid to conductor 63, completing the solenoid D circuit.

While the operation of the apparatus and especially my improved defrosting system would seem to be clear from the above description, it might be well to further state that when the operation.

apparatus is in normal refrigerating operation the motor. I operate: compressor I to compress the refrigerant and it passes in a gaseous-form from header It. to pipe; section H, T I2 throush thecondenser l3 into receiver I, through from 5 duit i1, expansion valve ll, pipe section 1 IQ, T section 2|, conduitll, through cooling coil I within the box' or showcase land from said coil 7 through the return or suction line -24,,icoil ll,

and conduit 20, back to header I for recirculation lo the refrigerating v as in the first instance, during The' expansion-valve II is set forl'responsive operationas, for instance. between 30 degrees and j 40 degreeslso'that' when ,the temperature 'i'nthe il box reaches 30 degrees the expansion valve closes.

stops the flow ofthe refrigerantand when'thetemperatureof said box rises to about 40 degrees the expansion valve opens and again permits refrigerant flow. i

In order to effect automatic defrosting of the device the time;cl0'ck A is set to operate the time switch or circuit makerand breaker 58 to close 21 and through auxiliary hot gas lin 31 to presthe solenoid C circuit and open its 'valve to initiate the defrosting period, the opening of which valve permits the heated gaseous refriger ant to be by-passed aroundcondenser l3 through hot gas line 21, valve C,

pipe sections

28, 29, 30, L valve D, sections, ,32, 3, and conduit 34 to T section and through ipe 2|, 011 a, pipe 24,

coil 25, and pipe section 8, back to header N, l. and through the comp essor; for recirculatlon through said coils during the defrosting period. At the end of said period t clock op'erates switch element 58 to open the s lenoid valve C circuit to close said valve and cause the hot gases to pass through condenser i3 and repeat the refri eration action as before. Howewer, when the I time clock operates to initiate the defrosting operation during an idle period of the compressor,

sure switch B operating circuit breaker 65 to close the motor circuit and start operation of the compressor and at the same time valve D is opened so that the hot gases pass throughthe 5 cooling coils to efiect their defrosting during a predetermined time period as heretobefore de-- 7 scribed, and which may be 15 minutes, 30 minutes, or any desired period, depending upon setting of the time clock.

It, will thus be apparent that I "have designed w an automatic defrosting system adapted to effect, not only under normal operating conditions automatic defrosting of the coils at predetermined w time intervals, but when the beginning of the f 3 defrosting period occurs when the compressor is not ru "ning, to at once buildup sufficient pressureig operate pressure responsive switch B and 1 quic, y effect starting of the compressor and tion of the defrosting system substan- 7o tially i ediately following the operation of the the oper time cl ,ck initiating. said defrosting period, said system/being simple in construction, manufacturable at a minimum cost, and eflicient for the purposes intended.

Although I have found in practice that the form of my invention illustrated in the accom- 1 ponying drawings and referred toin the above description as the preferred embodiment is the most eflicient and practical, yet realizing that conditions concurrent with the adoption of my invention will necessarily vary, I desire to emphasize that various minor changes in details of construction, proportion and arrangement of desire protected by Letters Patent is as set forth inthe following claims! l. 'A defrosting refrigeration circulation system including a compressor and a refrigerating coil,

a branched conduit interposed between the pressure; side of the compressorv and said coil, one of the branches .of said conduit constituting a passage for a refrigerant and including a condenser, the other branch of said conduit forming a passage for a hot defrosting gas from the compressor to said coil, pressure responsive means in communication with said hot gas passage, a time controlled electroresponsive means within said hot gas passage intermediate the compressor and point of communication of said pressure responsive means with said hot gas passage, and operable, to permit flow of a charge of hot gas from the compressor, to said'pressure responsive means to effect quick starting of the compressor, and a second electroresponsive means within said hot gas passage intermediate said point of communication of said pressure responsive means with said hot gas passage and said coil operable coincidently with the starting of the compressor" to permit flow of hot defrosting gas through said coil during the defrosting operation.

2. A defrosting refrigeration circulation system adapted for intermittent operation including a motor, an energizing circ it for the motor, a compressor driven by said m tor, and a refrig: crating coil, a branched conduit interposed be--' 5 tween the pressure side of the compressor and said coil, one of the branches of said conduit constituting a passage for a refrigerant and including a condenser, the other branch of said conduit forming a passage for a hot defrosting gas from the compressor to said .coil, pressure responsive means in said motor circuit and in com- I munication with said hot gas passage at a point intermediate its length, a time controlled electroresponsive valve means within said hot gas passage intermediate the communication point of the pressure responsive means with said hot gas passage and the compressor, and operable, when the defrosting operation is about to occur during an idle period of the compressor and when pressor, ,to' said pressure responsive means to taneously with the starting of the motor to permit flow of ot defrosting gas through said coil during 1; defrosting operation.

3. A defr sting refrigeration circulation sys- 7 tem adapted for intermittent operation including a motor, an energizing circuit for the motor, a compressor driven by said motor, and a refrigerating coil, a branched conduit interposed between the pressure side of the compressor and said coil, one of the branches of the conduit constituting a passage for a refrigerant and including a condenser, the other branch of said conduit forming a primary passage for a hot defrosting gas from the compressor to said coil, pressure responsive means in said motor circuit and in communication with the compressor, an auxiliary hot gas passage connecting the pressure responsive means with the primary hot gas passage, a time controlled electroresponsive means within said primary hot gas passage intermediate the point of connection of said auxiliary gas passage therewith and the compressor, and operable, when the defrosting operation is about to occur during an idle period of the compressor and when the prevailing pressure condition in the system is normally insuflicient to operate the pressure responsive means, to open position to permit flow of a charge of hot gas from the primary hot gas passage, through the auxiliary passage to said pressure responsiv means to operate the latter and eil'ect quick starting of the compressor, means within said primary passage intermediate said point of connection of the auxiliary gas passage with said primary passage and the coil and in said motor circuit operable simultaneously with starting of the compressor to permit flow of hot gas through said primary passage to and through said coil during the defrosting period.

4. A defrosting refrigeration circulation system adapted for automatic periodic operation including a motor, an energizing circuit for the motor, a compressor driven by said motor, and a refrigerating coil, a branched conduit interposed between the pressure side of the compressor and said coil, one of the branches of said conduit constituting a passage for a refrigerant and including a condenser, the other branch forming a hot gas passage by-passing the condenser and communicating with said coil, a pressure responsive means in said motor circuit and communicating with the compressor and said hot gas passage, a time controlled primary solenoid valve mounted in said hot gas passage intermediate the pressure responsive means point of communication with said hot gas passage and the compressor, and operable to open position to permit flow of a charge of hot gas from said hot gas passage to said pressure responsive means to efiect immediate starting of the compressor, and a second solenoid valve in said motor circuit adapted to close upon stoppage of said motor,

and a second electroresponsive said second valve being mounted in said hot gas passage intermediate the coil and said point of communication of the pressure responsive means with said hot gas passage, and operable simultaneously with the starting of the compressor to permit flow of hot gas to the coil during the defrosting operation.

5. A defrosting refrigeration circulation system adapted for automatic periodic operation including a motor, an energizing circuit for the motor, a compressor driven by said motor, and a refrigerating coil, a refrigerant conduit leading from the high pressure side of the compressor to the coil and including a condenser, a conduit constituting a primary hot gas passage extending from said pressure side of the compressor to said coil and by-passing said condenser, a pressure responsive means in said motor circuit and in communication with the compressor, an

auxiliary hot gas passage leading oil from said primary passage and communicating with said pressure responsive means, a solenoid valve mounted in the primary passage intermediate the auxiliary passage lead off point and the compressor, said valve being in circuit with a time controlled mechanism adapted to determine the defrosting period, and operable when the defrosting period is initiated while the compressor is idleand when the prevailing pressure condition in the system is insufficient to operate the .pressure responsive means, to permit passage therethrough of a charge of hot gas from the primary hot gas passage through said auxiliary passage to operate said pressure responsive means and effect quick starting of the compressor, and a second solenoid valve mounted in said primary hot gas passage intermediate said auxiliary passage lead off point and said coil and in the motor circuit and adapted to close upon stoppage of the compressor and operable simultaneously with the starting of the compressor to permit flow of hot gas to said coil during the defrosting operation.

ALBERT S. BARFIELD.

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

UNITED STATES PATENTS Number Name Date 1,912,841 Haymond June 6, 1933 2,049,625 Ruppricht Aug, 4, 1936 1,718,312 Shipley June 25, 1929 1,791,850 Stickney Feb. 10, 1931 1,757,602 Terry May 6, 1930 2,143,687 Crago Jan. 10, 1939