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US3861167A - Defrosting apparatus - Google Patents

Defrosting apparatus Download PDF

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Publication number
US3861167A
US3861167A US416750A US41675073A US3861167A US 3861167 A US3861167 A US 3861167A US 416750 A US416750 A US 416750A US 41675073 A US41675073 A US 41675073A US 3861167 A US3861167 A US 3861167A
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US
United States
Prior art keywords
temperature
evaporator
cooling medium
cooling
sensing
Prior art date
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
Application number
US416750A
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English (en)
Inventor
Kiyoichi Nijo
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Naniwa Sangyo Co Ltd
Original Assignee
Naniwa Sangyo Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Naniwa Sangyo Co Ltd filed Critical Naniwa Sangyo Co Ltd
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Publication of US3861167A publication Critical patent/US3861167A/en
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    • 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
    • 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
    • F25D21/002—Defroster control

Definitions

  • F25b 41/00 provided which stops the supply of cooling medium [58] Field of Search 62/156, 209, 227 when the temperatures at said three locations have dropped to 0 C and initiates again the supply of cool- [56] References Cited ing medium when the temperatures at said three loca- UNTTED STATES PATENTS tions have risen above 0 C, so that the supply of cooling medium is not reopened until frost which was 2 33;?
  • This invention relates to a defrosting apparatus in a domestic refrigerator or the like having an evaporator, and more particularly to a defrosting apparatus which always avoids excessive accumulation of frost on an evaporator for a domestic refrigerator or the like.
  • the inventor previously developed a novel temperature sensing device which comprises a pair of electrodes and water between the electrodes, thereby switching at C due to the difference in resistivity between liquid water and ice, as disclosed, for example, in US. Pat. No. 3,514,735.
  • a novel defrosting apparatus for a domestic refrigerator or the like wherein first and second temperature sensing devices are arranged respectively near the cooling medium inlet and outlet of a cooling coil of an evaporator for a domestic refrigerator or the like.
  • An electric control circuit which stops the supply of cooling medium to the evaporator when water in both of the first and second sensing devices has frozen and does not permit further supply of cooling medium until ice in both of the first and second sensing devices has melted, as disclosed, for example, in said US. Pat. No. 3,514,735 (see FIG. 6 and the corresponding disclosure of said Patent). ln this defrosting apparatus, frost formed on the evaporator is removed by melting during the stopping of the supply of cooling medium to the evaporator and said supply of cooling medium or cool ing operation is reopened first when frost on cooling fins near the inlet of cooling coil, where frost is usually formed first, has been removed.
  • the above defrosting apparatus is based on an assumption that the temperature of an evaporator always has its lowest value at the inlet of a cooling coil and, therefore, frost is formed first necessarily at a location near said inlet. It is well known, however, that the condensation temperature of a cooling medium rises when atmospheric temperature is high, such as in summer and, in this case, the cooling medium has its lowest temperature at a somewhat lower reach of the cooling coil rather than at the inlet of said coil, namely immediately after the expansion valve for the cooling medium, so that frost is formed on the evaporator first at such lower reach.
  • the aforestated defrosting apparatus therefore, exhibits the followingdisadvantages when the condensation temperature of the cooling medium becomes high due to a rise of atmospheric temperature or other reasons.
  • the cooling operation is reopened when some frost still remains on the evaporator because such reopening of cooling operation is ordered by the first sensing device which takes its 0N state when frost near the cooling medium inlet has been removed, but frost at such lower reach, where frost was formed first, has not yet been removed.
  • frost at such lower reach where frost was formed first, has not yet been removed.
  • frost always remaining on the evaporator at such lower reach prevents heat exchange between the evaporator and the atmosphere in the refrigerator so that cooling efficiency is lowered, requiring more power or energy for cooling.
  • said first temperature sensing device is displaced according to atmospheric temperature or condensation temperature of cooling medium but, in practice, that is too inconvenient.
  • the present invention aims at providing a novel defrosting apparatus which eliminates the aforestated disadvantages of the defrosting apparatus according to the prior art.
  • FIG. 1 is a diagrammatic view of an embodiment of the defrosting apparatus according to the present invention.
  • FIG. 2 is an enlarged sectional view of a temperature sensing device employed in thedefrosting apparatus shown in FIG. 1.
  • FIG. 1 an evaporator 10 for a domestic refrigerator or the like.
  • the evaporator 10 comprises a cooling coil 11 for flowing cooling medium or coolant therethrough and a number of spaced cooling fins 12 which are fixedly attached to the coil.
  • the coil 11 has a coolant inlet 11a and a coolant outlet 11b and, as is usual, between the inlet and the outlet is connected a refrigerating mechanism comprising compressor or refrigerating machine, condenser, expansion valve and the like (not shown).
  • Behind the evaporator 10 is arranged a pair of cooling fans 13 which are always driven to rotate so that the air in the refrigerator is forcedly brought into convection current.
  • first, second and third temperature sensing devices 14A, 14B and 14C are provided in a manner detailed hereinafter.
  • the first device 14A is fixedly attached to a cooling fin 12 near the inlet 11a of the cooling coil 11 so that said device 14A senses the temperature of the evaporator 10 near said inlet 11a.
  • the second device 14B is fixedly attached to a cooling fin 12 near a location on the evaporator 10 where said evaporator has its lowest temperature in case the condensation temperature of the cooling medium reaches the highest value during use of the refrigerator so that said device 148 senses the temperature of the evaporator 10 at such location.
  • the third device 14C is fixedly attached to a cooling fin 12 near the outlet 11b of the cooling coil 11 so that said device 14C senses the temperature of the evaporator 10 near said outlet 11b.
  • the temperature sensing device 14 shown in FIG. 2 comprises a cylindrically shaped housing 15 of metal, which contains water 16.
  • a plug 17 of non-conductive material seals the upper opening of the housing 15.
  • An electrode 18 extends through the plug 17 into the housing 15 so as to be immersed in the water 16.
  • a terminal 19 is connected to the electrode 18, and the housing 15 is fixedly attached to a cooling fin 12, as in the case of the aforestated devices 14A, 14B and 14C.
  • an electric potential is applied between the terminal 19 and the housing 15 an electric current flows between said terminal 19 and the housing 15 when the water 16 is in liquid state due to the small resistivity of liquid water.
  • a current does not flow substantially when the water 16 becomes solidified into ice at C due to the relatively high resistivity of ice. Therefore, the device 14 acts as a switch operating at 0 C whereby a temperature of 0 C is sensed.
  • each of the first, second and third temperature sensing devices employed in the defrosting apparatus comprises a pair of electrodes (in the case of the device shown in FIG. 2, the housing and the electrode 18) and water between the electrodes, thereby switching at 0 C due to the difference in resistivity between liquid water and ice.
  • Variations and modifications of such temperature sensing device are disclosed, for example, in said U.S. Pat. No. 3,514,735.
  • an electric control circuit 20 is connected to said first, second and third devices 14A, 14B and 14C.
  • the circuit 20 includes an electric power source 21 which is connected through a transformer 22 to a power output 23 having a terminal 24 connected to the terminals 19A, 19B and 19C of the devices 14A, 14B and 14C and another terminal 25 for supplying electric power to each of transistors detailed later.
  • the housings of the devices 14A, 14B and 14C are commonly grounded at 26 through the coil 11 and the fins 12.
  • Each of the terminals 19A, 19B and 19C of the devices 14A, 14B and 14C is connected to the bases of a pair of series-connected transistors 27A.
  • the control circuit 20 further includes a relay 31 which is connected to the power source 21 and to the micro-relays 30A, 30B and 30C.
  • the relay 31 in turn includes a switch 32 for actuating the refrigerating machine driving means (not shown) which is connected to terminals 33 and 34.
  • the relay 31 further includes a so-called self-maintenance circuit 35 having a coil 35a and a movable contact 35b, which circuit is connected to the micro-relays so that the circuit 35 opens the switch 32 when all of the three micro-relays 30A, 30B and 30C have been deenergized and closes said switch 32 when all of said three micro-relays have been energized, as shown in FIG. 1.
  • a further temperature sensing switch means 36 is provided in the refrigerator for sensing the temperature of atmosphere in said refrigerator.
  • Said means 36 is such that is employed in a usual thermostat and makes a switching operation at a variable set temperature so that it takes an ON state above the set temperature and an OFF state below said temperature.
  • the switch means 36 is connected in series to the third temperature sensing device 14C, as shown in FIG. 1.
  • the defrosting apparatus shown in FIG. 1 operates as follows: Before the refrigerator is cooled, considerable current flows through each of the first, second and third temperature sensing devices 14A, 14B and 14C so that all of the micro-relays 30A, 30B and 30C are energized by the transistors 27A, 28A; 27B, 28B; and 27C, 28C, whereby the switch 32 is closed to operate the refrigerating machine. Thus, cooling medium is supplied to the evaporator 10 so that the atmosphere in the refrigerator is gradually cooled. In this case, the temperature sensing switch means 36 is, of course, in an ON state.
  • frost is formed gradually on the evaporator 10. This formation of frost begins at a location on the evaporator where the cooling coil 11 or cooling medium flowing therethrough has the lowest temperature. Therefore, frost is formed on the evaporator 10 first near the first device 14A when the condensation temperature of the cooling medium is relatively low and near the second device 148 when said condensation temperature becomes high due to a rise of atmospheric temperature or other reasons. In any event, water in the first or second detector 14A or 148 near which frost is formed first becomes solidified into ice first so that the micro-relay 30A or 308 associated with the particular device is deenergized. In this case, however, the switch 32 in the relay 31 is not opened due to electric current flowing through the coil 35a of the self-maintenance circuit 35 which current keeps the movable contact 35b in the ON position.
  • frost is formed on the evaporator 10 near the second or first device 148 or 14A which still contains liquid water so that water in the said device 14B or 14A becomes solidified, whereby the micro-relay 308 or 30A associated with said device is deenergized.
  • the switch 32 is not opened due to the presence of the selfmaintenance circuit 35.
  • the switch 32 for actuating the refrigerating machine is opened first after a further cooling either when frost has been formed near the outlet llb of the cooling coil 11 and the third device 14C so that water in the third device 14C becomes solidified into ice or when the atmosphere in the refrigerator has been cooled to the set temperature on the switch means 36.
  • the micro-relay 30C is deenergized so that electric current flowing through the coil 35a is cut off to cause displacement of the movable contact 35b to OFF position whereby the switch 32 is opened.
  • the supply of cooling medium to the evaporator 10 is thus stopped.
  • frost formed on the evaporator near the first and second devices 14A and 14B has been supercooled below 0 C.
  • frost on said evaporator gradually melts. This melting or removal of frost proceeds gradually from the lower reach of the coil 11 to the upper reach of said coil.
  • the third sensing device 14C or the switch means 36 which has taken an OFF state takes an ON state due to thte melting of ice in the device 14C or a rise in the temperature of the atmosphere in the refrigerator to the set temperature on the means 36 so that electric current begins to flow through the third device 14C whereby the micro-relay 30C is energized again.
  • the switch 32 for actuating the refrigerating machine is not closed because the movable contact 35b in the self-maintenance circuit 35 is in the OFF position.
  • frost on the evaporator near the first and second devices 14A and 14B begins to melt. The melting of frost at such locations occurs first near the first device 14A or 148 which was turned into the OFF state later than the other device 14A or 148, as can easily be understood, and occurs then near the other device 14A or 143 which was turned into an oFF state earlier than said first device.
  • the switch 32 is still not closed, when only one of the first and second devices 14A and 14B turns into the ON state due to melting of frost near said one device and therefore melting of ice in said one device, because energizing of only one of themicro-relays 30A and 30B does not cause displacement of the movable contact 35b to its ON position.
  • the switch 32 for actuating the refrigerating machine is closed only when both of the first and second devices 14A and 148 turn to an ON state so that both of the micro-relays 30A and 30B are energized. Supply of cooling medium to the evaporator is thus initiated again or-reopened only when frost on said evaporatorhas been removed perfectly. Thereafter, the defrosting apparatus shown in FIG. 1 repeats the above operation.
  • frost especially supercooled frost near the first and second sensing devices 14A and 14B
  • the defrosting apparatus shown in FIG. 1 operates in a like manner because the temperature of the evaporator is lowered and raised in a same manner as stated before.
  • the defrosting apparatus removes frost on an evaporator employed in a refrigerator perfectly and automatically even when the condensation temperature of the cooling medium becomes high due to a rise of atmospheric temperature or other reasons such as, for example, a rise in the temperature of repeatedly used cooling air for a condenser for condensing the cooling medium before the evaporator.
  • the defrosting apparatus acts as a temperature control apparatus which always maintains temperature in the refrigerator at an approximately constant value notwithstanding various changes in atmospheric temperature and the amount and character of reserves in the refrigerator.
  • the defrosting apparatus according to the present invention is much simpler in construction and is offered with much lower cost than a defrosting apparatus of water spray type, heater type, hot gas type or the like according to the prior art.
  • the third temperature sensing device arranged near the outlet of the cooling coil prevents so-called liquid return to a compressor for the cooling medium because the said device stops the flow of cooling medium when the medium isgoing to leave the evaporator below a temperature of 0 C.
  • a defrosting apparatus comprising a first temperature sensing device mounted in heat transfer relation with a cooling medium inlet of the cooling coil for sensing the temperature of the evaporator near said inlet, a second temperature sensing device mounted in heat transfer relation with the evaporator where said evaporator has its lowest temperature in case the condensation temperature of the cooling medium becomes high due to a rise of atmospheric temperature for sensing the temperature of the evaporator near said location, a third temperature sensing device mounted in heat transfer relation with a cooling medium outlet of the cooling coil for sensing the temperature of the evaporator near said outlet, each of the temperature sensing devices comprising a pair of electrodes and water between the electrodes for switching at 0 C due to the difference in resistivity between liquid water and ice, and an electric control circuit for stopping the supply of cooling medium to the evaporator when water in all of the first, second and third sensing devices has frozen and continues stopping
  • the defrosting apparatus as claimed in claim 1 including temperature sensing switch means which senses the temperature of atmosphere in the domestic refrigerator and takes an ON state above a required temperature and an OFF state below a required temperature connected in series to said third temperature sensing device.
  • said electric control circuit includes amplifying means for electric current flowing between the electrodes of each of the sensing devices, a micro-relay for each sensing device which is energized by electric current flowing between the electrodes of the associated sensing device and through said amplifying means, and a relay including switch means for initiating and stopping the refrigerating machine, the said relay further including a self-maintenance circuit which opens the switch means when all of the three micro-relays have been deenergized and closes the switch means when all of the three micro-relays have been energized again.

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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)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
US416750A 1972-12-15 1973-11-19 Defrosting apparatus Expired - Lifetime US3861167A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP47125146A JPS4983048A (ja) 1972-12-15 1972-12-15

Publications (1)

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US3861167A true US3861167A (en) 1975-01-21

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US416750A Expired - Lifetime US3861167A (en) 1972-12-15 1973-11-19 Defrosting apparatus

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US (1) US3861167A (ja)
JP (1) JPS4983048A (ja)
AU (1) AU471757B2 (ja)
BE (1) BE807485A (ja)
CA (1) CA1004317A (ja)
DE (1) DE2360925C3 (ja)
FR (1) FR2210750B1 (ja)
GB (1) GB1442145A (ja)
IT (1) IT1002338B (ja)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4608832A (en) * 1983-12-27 1986-09-02 Geoscience, Ltd. Means and techniques useful in detecting frost
US5003786A (en) * 1989-04-07 1991-04-02 Mitsubishi Jukogyo Kabushiki Kaisha Refrigerating apparatus
US5069039A (en) * 1990-10-01 1991-12-03 General Cryogenics Incorporated Carbon dioxide refrigeration system
US5090209A (en) * 1990-10-01 1992-02-25 General Cryogenics Incorporated Enthalpy control for co2 refrigeration system
US5199275A (en) * 1990-10-01 1993-04-06 General Cryogenics Incorporated Refrigeration trailer
US5313787A (en) * 1990-10-01 1994-05-24 General Cryogenics Incorporated Refrigeration trailer
DE19613896A1 (de) * 1996-04-06 1997-10-09 Bayerische Motoren Werke Ag Fahrzeug-Klimaanlage mit einer elektronischen Steuereinheit
US20030131614A1 (en) * 2002-01-14 2003-07-17 Samsung Electronics Co., Ltd. Refrigerator and method of controlling the same
US6928830B1 (en) * 2004-07-29 2005-08-16 Carrier Corporation Linearly actuated manual fresh air exchange
WO2007066360A1 (en) * 2005-12-06 2007-06-14 Giuseppe Floris Device for detecting the characteristics of ice-snow-hoar frost
CN118376037A (zh) * 2024-06-24 2024-07-23 济南大森制冷工程有限公司 基于结霜厚度模型预测的除霜控制系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3539817A1 (de) * 1985-11-09 1987-05-14 Licentia Gmbh Verfahren zur messtechnischen ermittlung, anzeige und/oder der auswertung der an den kuehllamellen eines luftkuehlers auftretenden vereisung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2940278A (en) * 1957-05-14 1960-06-14 Thompson Selmar Raymond Defrosting control
US3097502A (en) * 1963-07-16 Defrost control apparatus
US3703086A (en) * 1970-03-11 1972-11-21 Naniwa Sangyo Co Ltd Temperature-regulating system in apparatuses for maintaining temperature constant

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3097502A (en) * 1963-07-16 Defrost control apparatus
US2940278A (en) * 1957-05-14 1960-06-14 Thompson Selmar Raymond Defrosting control
US3703086A (en) * 1970-03-11 1972-11-21 Naniwa Sangyo Co Ltd Temperature-regulating system in apparatuses for maintaining temperature constant

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4608832A (en) * 1983-12-27 1986-09-02 Geoscience, Ltd. Means and techniques useful in detecting frost
US5003786A (en) * 1989-04-07 1991-04-02 Mitsubishi Jukogyo Kabushiki Kaisha Refrigerating apparatus
US5069039A (en) * 1990-10-01 1991-12-03 General Cryogenics Incorporated Carbon dioxide refrigeration system
US5090209A (en) * 1990-10-01 1992-02-25 General Cryogenics Incorporated Enthalpy control for co2 refrigeration system
WO1992006325A1 (en) * 1990-10-01 1992-04-16 General Cryogenics Incorporated Enthalpy control for co2 refrigeration system
US5199275A (en) * 1990-10-01 1993-04-06 General Cryogenics Incorporated Refrigeration trailer
US5313787A (en) * 1990-10-01 1994-05-24 General Cryogenics Incorporated Refrigeration trailer
US5564277A (en) * 1990-10-01 1996-10-15 General Cryogenics Incorporated Dehumidifier for cryogenic refrigeration system
DE19613896A1 (de) * 1996-04-06 1997-10-09 Bayerische Motoren Werke Ag Fahrzeug-Klimaanlage mit einer elektronischen Steuereinheit
US20030131614A1 (en) * 2002-01-14 2003-07-17 Samsung Electronics Co., Ltd. Refrigerator and method of controlling the same
US6779352B2 (en) * 2002-01-14 2004-08-24 Samsung Electronics Co., Ltd. Refrigerator and method of controlling the same
US6928830B1 (en) * 2004-07-29 2005-08-16 Carrier Corporation Linearly actuated manual fresh air exchange
WO2007066360A1 (en) * 2005-12-06 2007-06-14 Giuseppe Floris Device for detecting the characteristics of ice-snow-hoar frost
CN118376037A (zh) * 2024-06-24 2024-07-23 济南大森制冷工程有限公司 基于结霜厚度模型预测的除霜控制系统

Also Published As

Publication number Publication date
IT1002338B (it) 1976-05-20
FR2210750A1 (ja) 1974-07-12
CA1004317A (en) 1977-01-25
BE807485A (fr) 1974-03-15
GB1442145A (en) 1976-07-07
AU471757B2 (en) 1976-04-29
DE2360925A1 (de) 1974-07-04
FR2210750B1 (ja) 1978-03-03
JPS4983048A (ja) 1974-08-09
DE2360925B2 (de) 1978-03-30
AU6304173A (en) 1975-05-29
DE2360925C3 (de) 1978-11-23

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