US3726104A - Refrigeration system defrost initiation apparatus - Google Patents

Refrigeration system defrost initiation apparatus Download PDF

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Publication number
US3726104A
US3726104A US00114882A US3726104DA US3726104A US 3726104 A US3726104 A US 3726104A US 00114882 A US00114882 A US 00114882A US 3726104D A US3726104D A US 3726104DA US 3726104 A US3726104 A US 3726104A
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United States
Prior art keywords
impeller
evaporator coil
switch
fluid
defrost
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US00114882A
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English (en)
Inventor
L Howland
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Thermo King Corp
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Thermo King Corp
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Filing date
Publication date
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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
    • F25D21/00—Defrosting; Preventing frosting; Removing condensed or defrost water
    • F25D21/02—Detecting the presence of frost or condensate
    • F25D21/025—Detecting the presence of frost or condensate using air pressure differential detectors

Definitions

  • the geared connection for the switch does not have to be in the vicinity of either the blower fan and its motor or the compressor and its motor.
  • the geared connection may be arranged to respond to either a change in speed or amount of fluid flow to be cooled through the evaporator coil or to the length of time that such fluid flows through the evaporator coil, or to both conditions in which case as the frost accumulates, the length of time of the fluid flow before defrost signal initiation could be reduced as frost accumulates.
  • an impeller is arranged to be revolved responsive to fluid that is moving during operation of the refrigeration system.
  • the moving fluid is preferably the fluid to be cooled by passing through the heat exchange fins of the evaporator coil but it could be other moving fluids such as the refrigerant.
  • the defrost initiation switch is connected to the revolving impeller through suitable gearing such that the switch will be operated in response to a condition of revolution of the impeller such as after a predetermined number of revolutions of the impeller corresponding to the length of time of operation of the system or such as a change in speed of revolution of the impeller corresponding to a change in condition of the fluid flow through the system.
  • the impeller may be located in a bypass around the evaporator coil and under such circumstances the switch may respond to a predetermined number of impeller revolutions as indicated by clock timer gearing driven by the impeller to thus indicate a total time of operation of the system.
  • the impeller and clock timer gearing is driven faster by the increased fluid flow through the bypass around the evaporator coil as the evaporator coil plugs with frost to thereby operate the defrost signal switch sooner than it would be operated if the coil is not plugged with frost.
  • the switch may be a centrifugal switch connected by gearing to the impeller and the gearing would not be clock timer gearing but instead would be suitable reduction or step up gearing for obtaining the required rotation of the centrifugal switch when the impeller is revolving at a predetermined speed indicative of the rate of fluid flow through the evaporator coil which corresponds to the condition of an objectional build up of frost on the evaporator coil.
  • the switch is a centrifugal switch and the impeller is located in the bypass around the evaporator coil, the switch would be operated by an increase in speed of revolution.
  • the centrifugal switch would respond to a reduction in speed of revolution of the impeller for initiating a defrost signal because of frost buildup.
  • FIG. 1 is a side elevational view, partly in section, of
  • defrost initiation switch is driven by a clock timer gear train responsive to fluid flow through the evaporator coil
  • FIG. 2 is a view similar to FIG. I but showing a modified arrangement in which the defrost initiation switch impeller and gear train is positioned within a bypass conduit around the evaporator coil;
  • FIG. 3 is a diagrammatic illustration of yet another form of the invention in which the impeller and defrost initiation switch are arranged to respond to the movement of gaseous refrigerant in the refrigeration system.
  • FIG. 4 is a fragmentary side elevational view, partly in section, of a modified form of the invention in which the defrost initiating switch is a centrifugal switch driven by a gear train connected to the impeller that is positioned downstream of the evaporator coil; and
  • the evaporator coil 10 is shown to be mounted on a transverse panel wall 11 within the duct 12 of the refrigeration system.
  • the fluid, usually air, to be cooled by the refrigeration system is blown by the blower fan 13 in the direction of the arrows through the evaporator coil 10.
  • the transverse duct wall or partition 11 is provided with an opening 14 to one side of the evaporator coil in which is positioned the rotatable impeller 15 connected by the gear train 16 to the defrost initiation signal switch 17.
  • the gear train 16 is a simple clock timer gear train that is driven by the impeller 15 instead of the conventional clock spring.
  • the impeller 15 will be continuously revolved so long as the blower fan 13 is revolving to move the fluid to be cooled through the evaporator coil 10.
  • the gear train 16 will be effective to close the defrost initiation switch 17 and transmit a signal through the conductors 18 and 19 to the appropriate apparatus for reversing the operation of the refrigeration system for purposes of defrosting the evaporator coil 10 in a manner well known to those skilled in the art.
  • the gear train l6 is a clock timer gear train for integrating the total number of revolutions of the impeller 15, the arrangement may be modified by providing that the defrost switch 17 is a centrifugally operated switch responsive to the speed of rotation of the shaft 21.
  • the gear train 16 would preferably be a reduction gearing to allow the impeller 15 to rotate at considerable speed and with very little effort before the shaft 21 is rotated at sufflcient speed to close the centrifugal switch 17.
  • the centrifugal switch 17 can be either of the normally open or normally closed variety depending upon the type of signal circuits with which the switch is connected. Therefore, whether or not the switch is normally open or normally closed, it will be operated from its normal condition to its operated condition only when the speed of revolution of the impeller 15 is such as to indicate the condition of a plugged evaporator coil.
  • FIG. 2 of the drawing a modified form of the invention is shown wherein the impeller 15, gear train 16 and switch 17 is enclosed in a bypass duct 25 connected through the main duct wall 12 on both sides of the evaporator coil 10.
  • a portion of the fluid to be moved by the blower 13 through the evaporator coil 10 is diverted through the bypass duct 25 around the evaporator coil.
  • the impeller 15 When the evaporator coil 10 becomes plugged with frost, the amount of fluid moving through bypass duct increases in pressure and therefore causes the impeller 15 to revolve at increased speed to either accelerate the gear train 16 for purposes of timing the number of revolutions of the impeller 15 or for purposes of responding to the increased speed of rotation of the impeller 15 and operate the defrost initiation switch 17 as previously described.
  • the impeller 15, gear train 16 and defrost initiation switch 17 are positioned within the duct downstream of the evaporator coil 10.
  • the impeller 15 and associated apparatus may be positioned upstream of the evaporator coil 10.
  • the effect would be substantially the same in that the plugging of the evaporator coil with frost would cause a reduction of fluid flow past the impeller 15 and through the evaporator coil 10 so that the impeller would rotate at lower speed to cause the appropriate operation of the defrost initiation switch 17.
  • FIG. 3 of the drawing in another modification of the invention is shown as it may be applied to a refrigeration system in which a compressor such as shown at 30 is connected by the relatively large diameter suction line 31 to the discharge of the evaporator coil 32.
  • Compressed refrigerant gas from the compressor 30 is connected by the line 33 to the condensing coil 34 whose discharge is connected by the line 35 to the expansion device or valve 36 and the inlet of the evaporator coil 32.
  • the revolving impeller 40 is mounted within the suction line 31 in any suitable manner not shown in detail and is connected through the gear train 41 to the defrost initiation switch 42.
  • the impeller 40 is revolved by the motion of the gaseous refrigerant in the line 31 being drawn into the intake of the compressor 30 during operation of the refrigeration system and the gear train will therefore function to integrate the total time of operation of the system between periods of defrosting to be initiated by the defrost signal initiating switch 42.
  • the impeller 40 may be arranged to respond to the motion of the refrigerant fluid whether or not it is in the gaseous or liquid state throughout the system.
  • a defrost initiation apparatus in combination with a refrigeration system having an evaporator coil to be occasionally defrosted, the refrigerator system having a fluid in motion passing in heat exchange relation to be cooled by said coil during its operation, a bypass passage around said coil for a portion of said fluid, an impeller enclosed within said bypass passage and whereby said switch means is adapted to count the number of revolutions of said impeller and is actuated to thereby initiate a defrost cycle for said system after a predetermined number of said revolutions.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Defrosting Systems (AREA)
  • Cold Air Circulating Systems And Constructional Details In Refrigerators (AREA)
US00114882A 1971-02-12 1971-02-12 Refrigeration system defrost initiation apparatus Expired - Lifetime US3726104A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US11488271A 1971-02-12 1971-02-12

Publications (1)

Publication Number Publication Date
US3726104A true US3726104A (en) 1973-04-10

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ID=22357988

Family Applications (1)

Application Number Title Priority Date Filing Date
US00114882A Expired - Lifetime US3726104A (en) 1971-02-12 1971-02-12 Refrigeration system defrost initiation apparatus

Country Status (7)

Country Link
US (1) US3726104A (enExample)
AU (1) AU461420B2 (enExample)
BE (1) BE779169A (enExample)
CA (1) CA940723A (enExample)
DE (1) DE2204722C3 (enExample)
FR (1) FR2125401B1 (enExample)
GB (1) GB1369026A (enExample)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4492151A (en) * 1982-03-05 1985-01-08 Michele Mattei Eliane Air pressurizers/conditioners especially for work cabs in a polluted atmosphere
US5201185A (en) * 1991-07-11 1993-04-13 Thermo King Corporation Method of operating a transport refrigeration unit
WO2004088221A1 (de) * 2003-04-04 2004-10-14 BSH Bosch und Siemens Hausgeräte GmbH Kältegerät mit adaptiver abtauautomatik und abtauverfahren dafür

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN112066618B (zh) * 2020-09-15 2021-12-21 长虹美菱股份有限公司 一种立式冷冻箱气压调节微霜装置

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1984053A (en) * 1930-07-07 1934-12-11 Gen Fire Extinguisher Co Automatically-controlled refrigerative system
US2346037A (en) * 1942-10-29 1944-04-04 Willson Products Inc Resettable meter for indicating use of respirator filter canisters
US2882364A (en) * 1956-10-15 1959-04-14 Samuel C Warren Safety switch
US3107499A (en) * 1961-09-22 1963-10-22 Honeywell Regulator Co Control apparatus
US3159981A (en) * 1963-03-14 1964-12-08 Gen Electric Heat pump including frost control means
US3159980A (en) * 1963-07-17 1964-12-08 Gen Electric Refrigerator including combination evaporator fan motor and defrost control
US3355904A (en) * 1966-01-21 1967-12-05 Texas Instruments Inc Differential fluid velocity sensing
US3643457A (en) * 1970-11-20 1972-02-22 Westinghouse Electric Corp Frost detector for refrigeration system

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB391363A (en) * 1931-11-03 1933-04-27 Fox Robert Improvements in alarm devices for fire-extinguishing sprinkler systems
US3370437A (en) * 1966-06-14 1968-02-27 Gen Motors Corp Defrosting system
US3377817A (en) * 1966-12-27 1968-04-16 Trane Co Defrost control for heating and cooling refrigeration systems

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1984053A (en) * 1930-07-07 1934-12-11 Gen Fire Extinguisher Co Automatically-controlled refrigerative system
US2346037A (en) * 1942-10-29 1944-04-04 Willson Products Inc Resettable meter for indicating use of respirator filter canisters
US2882364A (en) * 1956-10-15 1959-04-14 Samuel C Warren Safety switch
US3107499A (en) * 1961-09-22 1963-10-22 Honeywell Regulator Co Control apparatus
US3159981A (en) * 1963-03-14 1964-12-08 Gen Electric Heat pump including frost control means
US3159980A (en) * 1963-07-17 1964-12-08 Gen Electric Refrigerator including combination evaporator fan motor and defrost control
US3355904A (en) * 1966-01-21 1967-12-05 Texas Instruments Inc Differential fluid velocity sensing
US3643457A (en) * 1970-11-20 1972-02-22 Westinghouse Electric Corp Frost detector for refrigeration system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4492151A (en) * 1982-03-05 1985-01-08 Michele Mattei Eliane Air pressurizers/conditioners especially for work cabs in a polluted atmosphere
US5201185A (en) * 1991-07-11 1993-04-13 Thermo King Corporation Method of operating a transport refrigeration unit
WO2004088221A1 (de) * 2003-04-04 2004-10-14 BSH Bosch und Siemens Hausgeräte GmbH Kältegerät mit adaptiver abtauautomatik und abtauverfahren dafür
US20070006600A1 (en) * 2003-04-04 2007-01-11 Bsh Bosch Und Siemens Hausgeråte Gmbh Refrigeration device with adaptive automatic defrosting and corresponding defrosting method
RU2380627C2 (ru) * 2003-04-04 2010-01-27 Бсх Бош Унд Сименс Хаусгерете Гмбх Холодильный аппарат с адаптивной системой автоматического оттаивания

Also Published As

Publication number Publication date
DE2204722B2 (de) 1981-06-25
FR2125401B1 (enExample) 1976-07-23
AU461420B2 (en) 1975-05-29
BE779169A (fr) 1972-08-10
FR2125401A1 (enExample) 1972-09-29
DE2204722C3 (de) 1982-02-04
AU3736071A (en) 1973-06-28
DE2204722A1 (de) 1972-08-24
CA940723A (en) 1974-01-29
GB1369026A (en) 1974-10-02

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