US3359749A - Differential control device - Google Patents

Differential control device Download PDF

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Publication number
US3359749A
US3359749A US464630A US46463065A US3359749A US 3359749 A US3359749 A US 3359749A US 464630 A US464630 A US 464630A US 46463065 A US46463065 A US 46463065A US 3359749 A US3359749 A US 3359749A
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United States
Prior art keywords
diaphragm
heat exchanger
control device
air
differential
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
US464630A
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English (en)
Inventor
Leland L Howland
Harold E Mcclure
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Thermo King Corp
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Thermo King Corp
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 Thermo King Corp filed Critical Thermo King Corp
Priority to US464630A priority Critical patent/US3359749A/en
Priority to GB25924/66A priority patent/GB1131733A/en
Priority to NL6608271A priority patent/NL6608271A/xx
Priority to DE19661523663 priority patent/DE1523663C/de
Priority to ES0327986A priority patent/ES327986A1/es
Application granted granted Critical
Publication of US3359749A publication Critical patent/US3359749A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B47/00—Arrangements for preventing or removing deposits or corrosion, not provided for in another subclass
    • F25B47/02—Defrosting cycles
    • F25B47/022—Defrosting cycles hot gas defrosting
    • 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

  • This invention relates to improvements in the control of a system involving differential factors.
  • the invention is concerned with a control device that is used under conditions where a differential in factors, such as pressure, is subject to change or variation. More particularly, the invention is concerned with the control of the defrosting of a refrigerant heat exchanger used in a sysem where the rate or volume of air which is forced through the heat exchanger is not constant, but is subject to variation.
  • the air which is circulated into contact with the refrigerant heat exchanger will generally contain moisture that congeals on the surface of the heat exchanger, and thus impedes the flow of air between the conduits and the fins that extend between said conduits. Removal of the congealed moisture is effected by defrosting, which may be accomplished either by the application of external heat, or a modification of the refrigerant circuit to obtain heat from the compressed refrigerant gases.
  • frost or congealed moisture collects on the surface of the heat exchanger, it will impede the flow of air between the coils and fins that form the heat exchanger. Unless this condition is corrected by defrosting, the layer of frost will build up to a point where little if any air can flow through the heat exchanger. Since such air is generally forced through the heat exchanger by means of a fan or blower, as the layer of frost accumulates, a substantial differential in air pressure will be developed on the opposite sides of the heat exchanger, and this differential may be utilized to actuate the defrosting means.
  • control device which responds to pressure differential, and which is effective even when such differential is subject to change.
  • control is responsive to a first differential when the force of the air or other flow is relatively low, and to another differential when the force of air or other flow is relatively high.
  • An object of the invention is to provide a control device which is adapted to operate on a variation in differential between two factors, and particularly where one of the factors is subject to variation.
  • Another object is to provide a control device embody ing a diaphragm which responds to a differential in pressure, together with means for controlling the movement of the diaphragm to prevent a responsive movement thereof when, under certain conditions the differential is changed.
  • a further object is to control the defrosting of a refrigerant heat exchanger under conditions where the rate of air flow with respect to the heat exchanger is subject to variation as between a low rate of air flow and a high rate of air flow.
  • FIG. 1 is a cross sectional view of a diaphragm operated control device
  • FIG. 2 illustrates a modification of a portion of the structure shown in FIG. 1;
  • FIG. 3 is a schematic view of a refrigeration unit, together With a control device of the type disclosed in either FIG. 1 or 2, for controlling the defrosting of the refrigerant heat exchanger.
  • Reference character 12 designates a diaphragm chamber within which is located a flexibly movable diaphragm 14.
  • a conduit 16 communicates with the interior of chamber 12 on one side of the diaphragm 14, and extends from what is potentially a higher source of pressure, while on the other side of diaphragm 14, a conduit 18 joins chamber 12 with a potentially lower source of pressure.
  • Mounted on the exterior of chamber 12 is an electric switch 20 provided with an actuator 22 disposed within the interior of chamber 12 and in contact with the diaphragm 14 to be actuated by the movement of said diaphragm.
  • a solenoid 24 is mounted on a bracket 26 that is secured to chamber :12, and the solenoid is made adjustable with respect to bracket 26 by a pair of fastening means 28, 28a, that extend through slotted portions, not shown, in bracket 26.
  • the solenoid 24 contains a movable armature 30 that carries a depending pin 32, which engages a coil spring 34 mounted on the surface of diaphragm 14.
  • the armature 30 and its depending pin 32 are made adjustable with respect to the spring 34 and diaphragm 14 by means of an adjusting screw 36 carried by bracket 26.
  • the armature 3 0 and its associated parts are shown in the position they assume when the inductance coil of solenoid 24 is de-energized.
  • FIG. 2 the portion of the control device 10 shown here is substantially identical to that disclosed in FIG. 1, except that in this figure the armature designated at 30a is also shown in the position it assumes when the inductance coil of solenoid 24a is deenergized.
  • a coil spring 38 is disposed between armature 30a and an adjusting screw 36a carried by bracket 26a.
  • the armature 34in moves upwardly against spring 38.
  • FIG. 3 is disclosed a refrigeration system composed of a compressor 46, whose high pressure or discharge side is connected to a conduit 42 that extends to a condenser 44.
  • a receiver 46 is connected to the outlet end of condenser 4-4.
  • a conduit 48 extends from an opposite end of receiver 46 to a refrigerant evaporator 50, and the flow of refrigerant fiuid to the evaporator 50 is controlled by an expansion valve 52 under the influence of a temperature sensitive element 54, that is in thermal contact with a portion of evaporator 56.
  • the outlet end of the evaporator 50 is connected by a conduit 56 to the low pressure side of compressor 40.
  • a hot gas line 58 extends from conduit 42 to evaporator 50 at a point adjacent the inlet end of the evaporator, and the flow of fluid through conduit 58 is controlled by a valve 6t), under the influence of an electromagnetic actuator 62. It should be understood that the evaporator 55 may be defrosted by other conventional means under the control of a similar electromagnetic device.
  • Compressor 40 is driven by a prime mover 64, which may be either an internal combustion engine, or a twospeed electric motor.
  • the prime mover 64 operates either at a low speed or at a higher speed under the control of a speed control device 66 which is actuated by an electromagnetic device 68 under the influence of a thermostatic control device 70 having a temperature sensitive portion 71.
  • the evaporator 50 is provided with a multiplicity of heat conducting fins 72, and is located within an enclosure 74, which would normally be insulated.
  • a fan or blower 76 is provided for circulating the air through the evaporator within the enclosure 74.
  • the fan 76 is illustrated as being driven by the prime mover 64- through a mechanical connection 78, although it should be understood that if desired, fan 76 can also be driven by an independent prime mover, provided said prime mover is also adapted to operate at a low speed, and high speed.
  • Conduit 16 which is an open ended tube, has its outer open end extending to enclosure 74 between fan 76, and refrigerant heat exchanger 50, at a point which may be regarded as a high pressure area.
  • Conduit 18 is, likewise, an open ended tube, and has its outer open end extending into enclosure 74 on a side of the heat exchanger t) opposite from fan 76, or in an area which may be regarded as a low pressure area.
  • a battery 80 forms a source of electrical power, and is connected to a conductor 82 that extends to a conductor 84.
  • Conductor 84 extends to the thermostatic control device 70, and to one pole of switch 20.
  • a conductor 86 extends from the thermostatic control device 70 to the electromagnetic device 68, and a branch conductor 88 extends from conductor 86 to solenoid 24.
  • a conductor 90 extends from the other pole of switch 20 to the electromagnetic device 62 that serves to operate valve 6t).
  • the operation of the invention, in conjunction with a refrigeration system, will now be described.
  • the purpose of the refrigeration system is to maintain a predetermined temperature within the enclosure 74, and to all practical extent, this is accomplished in a conventional manner.
  • the prime mover 64 is in continuous operation, and is continuously driving compressor 40 and fan 76 at either a low speed, where only minimal refrigeration is required, or at a higher speed when there is a demand for refrigeration within the enclosure '74.
  • the refrigerant fluid which is discharged from the compressor 40 passes through the conduit 42 to the condenser 44, and thence to the receiver 46. Liquid refrigerant flows from the receiver 46 through conduit 48 to evaporator 5t under control of the expansion valve 52 whose operation is controlled under the influence of the temperature sensitive portion 54.
  • the refrigerant vapors t formed within the evaporator are returned to the compressor 40 through conduit 56.
  • the fan or blower 76 Since the fan or blower 76 is in continuous operation, it is circulating air within the enclosure 74 into contact with the refrigerant heat exchanger'composed of evaporator 5t and its heat conducting fins 72. Assuming that said air contains moisture, the latter will congeal on the cold surfaces of coil 5% and fins 72, and will thus progressively impede the flow of air through the heat exchanger, and thus require periodic removal by defrosting of coil 50.
  • the control device it) is adapted to control the actuation of the electromagnetic device 62, and thus valve in response to a differential in pressure on the opposite sides of the heat exchanger 5t as reflected by the pressure conducted to chamber 12 on the opposite sides of diaphragm 14 by conduits 16 and 118.
  • the solenoid 24 is actuated and then adjusted on the bracket 26 by means of the adjusting screws 28 and 28a to a point relative to the spring 34 and diaphragm M, where fiexure of the diaphragm occurs at a predetermined high pressure which would exist when the fan 76 is operating at high speed, and the flow of air through the heat exchanger St? has been reduced to about 50% of its normal flow.
  • the adjustment of the control device, shown in FIG. 2, is identical to that disclosed with respect to the control device in FIG. 1, except that in this modification, the armature 30a is biased in its unattracted position by spring 38, and when solenoid 24a is energized, the armature 30a moves upwardly against the bias of spring 33.
  • the switch 20 can be used in a circuit where the termination of defrosting and the resumption of the refrigeration cycle is controlled by a thermal switch that responds to the temperature of the refrigerant heat exchanger.
  • the refrigerant heat exchanger composed of evaporator 50 and its fins 72 become coated with frost or ice, there is relatively little heat exchange with the air in enclosure 74, and the temperature Within the enclosure may rise.
  • the control device 70 through its sensing element 71, will demand additional refrigeration, and the thermostat will energize the electromagnetic device 68 to cause the control device 66 to increase the speed of the prime mover 74.
  • the solenoid 24 Concomitant with the energization of the control device 68, the solenoid 24 is also energized, driving the armature 30 outwardly to place additional pressure on the coil spring 34 to impede the flexing of diaphragm 14 until the setting thereof, representing the greater differential, has been exceeded.
  • electromagnetic device 68 and the solenoid 24a would be energized by control 70 when the prime mover 64 is in its low speed operation, and would be de-energized when the prime mover is in its high speed operation.
  • the relationship of coil spring 38 to coil spring 34 is such that when solenoid 24a is deenergized, a relatively high differential would be required to flex the diaphragm 14, and energization of solenoid 24a during the low speed operation of the prime mover 64 would cause the armature 30a to move against the bias of spring 38 and thereby diminish the pressure on spring 34.
  • defrosting of the refrigerant heat exchanger would occur in the manner as previously described.
  • the principal advantage of this invention is that it provides differential control of a mechanism, such as the defrosting of a refrigerant system under two conditions, such as when the air is being circulated at a low rate and pressure, but also providing adequate control when the pressure differential is changed, as by the circulation of air at a higher rate or pressure, and thus compensating for the change in differential.
  • the present invention provides automatic defrosting under either condition, and will generally provide rapid defrosting when air flow through the refrigerant heat exchanger is substantially impeded.
  • the present invention will also find utility in other fields where a fluid is passed through a restricted area, such as a filtration system, and wherein modification of the system is required when flow is substantially impeded.
  • a control device comprising a controlling member, a diaphragm which is subject to movement relative to said controlling member, means for imposing separate forces on opposite sides of said diaphragm, resilient means coacting with said diaphragm in opposition to one of said forces, and a motor means which is energized with the increase of said one of said forces and cooperating with said diaphragm in opposition to the increase of said one force.
  • a control device comprising a controlling member, a diaphragm which is subject to movement relative to said controlling member, means for imposing separate forces on opposite sides of said diaphragm, resilient means coacting with said diaphragm in opposition to one of said forces, and motor means which is energized with the increase of said one force coacting with said resilient means in opposition to the increase in said one force.
  • a blower which is operative at a low speed and a higher speed circulating air relative to said heat exchanger, means for controlling the defrosting of said heat exchanger;
  • a control device for controlling said defrosting control means when said blower is operative at said higher speed comprising a controlling member operatively connected to said defrosting control means, a diaphragm operatively associated with said controlling member, means for imposing on the opposite sides of said diaphragm the air pressure existing on opposite sides of said heat exchanger, and a motor which is energized when said blower is circulating air at said higher rate coacting with said diaphragm in opposition to the increase in pressure on one side of said diaphragm.
  • a refrigeraton system embodying in combination, a refrigerant heat exchanger, control means for defrosting said heat exchanger, a blower for circulating air relative to said heat exchanger at a low speed and a higher speed, control means for controlling the speed of said blower, means operatively associated with said defrosting control means and sensitive to a differential in pressure on opposite sides of said heat exchanger for initiating defrosting on a change in said differential when said blower is operating at one of said speeds, and means actuated by said speed control means for changing a factor in the actuation of said defrosting control means when said blower is operating at said other speed.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Devices That Are Associated With Refrigeration Equipment (AREA)
  • Defrosting Systems (AREA)
  • Folding Of Thin Sheet-Like Materials, Special Discharging Devices, And Others (AREA)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
US464630A 1965-06-17 1965-06-17 Differential control device Expired - Lifetime US3359749A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US464630A US3359749A (en) 1965-06-17 1965-06-17 Differential control device
GB25924/66A GB1131733A (en) 1965-06-17 1966-06-10 A fluid-pressure actuated control device
NL6608271A NL6608271A (enrdf_load_stackoverflow) 1965-06-17 1966-06-15
DE19661523663 DE1523663C (de) 1965-06-17 1966-06-15 Automatische Abtaueinrichtung für eine Kühlanlage
ES0327986A ES327986A1 (es) 1965-06-17 1966-06-16 Un dispositivo de control para controlar un aparato en funcion de una fuerza producida por el funcionamiento de dicho aparato.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US464630A US3359749A (en) 1965-06-17 1965-06-17 Differential control device

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US3359749A true US3359749A (en) 1967-12-26

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US464630A Expired - Lifetime US3359749A (en) 1965-06-17 1965-06-17 Differential control device

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US (1) US3359749A (enrdf_load_stackoverflow)
ES (1) ES327986A1 (enrdf_load_stackoverflow)
GB (1) GB1131733A (enrdf_load_stackoverflow)
NL (1) NL6608271A (enrdf_load_stackoverflow)

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3411310A (en) * 1967-03-17 1968-11-19 Ranco Inc Time delay mechanism for refrigeration system
US3427818A (en) * 1966-12-19 1969-02-18 Modine Mfg Co Electronic control
US3831392A (en) * 1973-05-21 1974-08-27 Heil Quaker Corp Air conditioner with air flow sensor
US3831391A (en) * 1972-12-29 1974-08-27 Acf Ind Inc Apparatus for testing the operation of the defrost switch in an air conditioning unit
JPS5198858U (enrdf_load_stackoverflow) * 1975-02-07 1976-08-07
US4226091A (en) * 1978-04-26 1980-10-07 Studsvik Energiteknik Ab Heat pump containing a piston compressor and driven by a piston engine
US4347711A (en) * 1980-07-25 1982-09-07 The Garrett Corporation Heat-actuated space conditioning unit with bottoming cycle
US4831833A (en) * 1987-07-13 1989-05-23 Parker Hannifin Corporation Frost detection system for refrigeration apparatus
US5101639A (en) * 1990-05-21 1992-04-07 Honeywell Inc. Air handling system utilizing direct expansion cooling
WO2004013548A3 (en) * 2002-08-05 2004-06-03 Water Company Device and method for operating a refrigeration cycle without evaporator icing
US20060242973A1 (en) * 2003-04-04 2006-11-02 Bsh Bosch Und Siemens Hausgerate Gmbh Refrigeration device and operating method for the same
US20070006600A1 (en) * 2003-04-04 2007-01-11 Bsh Bosch Und Siemens Hausgeråte Gmbh Refrigeration device with adaptive automatic defrosting and corresponding defrosting method
WO2017105983A1 (en) * 2015-12-18 2017-06-22 Carrier Corporation Methods and systems for checking proper airflow within a container

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3990845B1 (en) 2019-06-26 2024-04-17 Carrier Corporation Transportation refrigeration unit with adaptive defrost

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2147678A (en) * 1933-11-29 1939-02-21 Westinghouse Electric & Mfg Co Cooling apparatus
US2216589A (en) * 1937-06-28 1940-10-01 Gen Motors Corp Refrigerating apparatus
US2975611A (en) * 1959-08-31 1961-03-21 Gen Electric Control system for air conditioning units
US2992542A (en) * 1956-10-23 1961-07-18 Garrett Corp Ice formation control for air conditioning systems
US3004399A (en) * 1958-12-01 1961-10-17 Gen Controls Co Automatic defrost control for refrigerators or heat pump systems

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2147678A (en) * 1933-11-29 1939-02-21 Westinghouse Electric & Mfg Co Cooling apparatus
US2216589A (en) * 1937-06-28 1940-10-01 Gen Motors Corp Refrigerating apparatus
US2992542A (en) * 1956-10-23 1961-07-18 Garrett Corp Ice formation control for air conditioning systems
US3004399A (en) * 1958-12-01 1961-10-17 Gen Controls Co Automatic defrost control for refrigerators or heat pump systems
US2975611A (en) * 1959-08-31 1961-03-21 Gen Electric Control system for air conditioning units

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3427818A (en) * 1966-12-19 1969-02-18 Modine Mfg Co Electronic control
US3411310A (en) * 1967-03-17 1968-11-19 Ranco Inc Time delay mechanism for refrigeration system
US3831391A (en) * 1972-12-29 1974-08-27 Acf Ind Inc Apparatus for testing the operation of the defrost switch in an air conditioning unit
US3831392A (en) * 1973-05-21 1974-08-27 Heil Quaker Corp Air conditioner with air flow sensor
JPS5198858U (enrdf_load_stackoverflow) * 1975-02-07 1976-08-07
US4226091A (en) * 1978-04-26 1980-10-07 Studsvik Energiteknik Ab Heat pump containing a piston compressor and driven by a piston engine
US4347711A (en) * 1980-07-25 1982-09-07 The Garrett Corporation Heat-actuated space conditioning unit with bottoming cycle
US4831833A (en) * 1987-07-13 1989-05-23 Parker Hannifin Corporation Frost detection system for refrigeration apparatus
US5101639A (en) * 1990-05-21 1992-04-07 Honeywell Inc. Air handling system utilizing direct expansion cooling
WO2004013548A3 (en) * 2002-08-05 2004-06-03 Water Company Device and method for operating a refrigeration cycle without evaporator icing
EP1535005A4 (en) * 2002-08-05 2008-04-23 Water Company DEVICE AND METHOD FOR OPERATING A COOLING CYCLE WITHOUT INCORPORATING THE EVAPORATOR
US20060242973A1 (en) * 2003-04-04 2006-11-02 Bsh Bosch Und Siemens Hausgerate Gmbh Refrigeration device and operating method for the same
US20070006600A1 (en) * 2003-04-04 2007-01-11 Bsh Bosch Und Siemens Hausgeråte Gmbh Refrigeration device with adaptive automatic defrosting and corresponding defrosting method
WO2017105983A1 (en) * 2015-12-18 2017-06-22 Carrier Corporation Methods and systems for checking proper airflow within a container
US10663211B2 (en) 2015-12-18 2020-05-26 Carrier Corporation Methods and systems for checking proper airflow within a container

Also Published As

Publication number Publication date
ES327986A1 (es) 1967-04-01
NL6608271A (enrdf_load_stackoverflow) 1966-12-19
GB1131733A (en) 1968-10-23
DE1523663A1 (de) 1969-06-26

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